Environmental Impact Assessment for Proposed
Sethusamudram Ship Channel Project
Sponsor
Tuticorin Port Trust, Tuticorin
National Environmental Engineering Research Institute
Nehru Marg, Nagpur - 440 020
August 2004

Environmental Impact Assessment for
Proposed Sethusamudram Ship Channel Project
Sponsor
Tuticorin Port Trust, Tuticorin
Point Calemer
INDIA
BAY OF
BENGAL
Palk Strait
INDIA
PALK BAY
Tamil Nadu
Mandapam
Rameshwaram
Mandapam
Keelakkarai
LANKA
Valinokkam
Terkmukkaiyur
Vembar
Vaipar
SRI
Tuticorin
GULF OF MANNAR
National Environmental Engineering Research Institute
Nehru Marg, Nagpur - 440 020
August 2004

Contents
Item Page
No.
List of Figures vi
List of Tables xi
List of Plates xv
List of Drawings xvi
1. Introduction 1.1-1. 25
1.1 Preamble 1.1
1.2 Earlier Studies Involving Creation of Canal 1.3
1.3 Project Region 1.7
1.4 Geomorphology of Study Region 1.9
1.5 Environmental Impact Assessment (EIA) 1.14
1.5.1 Objectives of EIA Study 1.15
1.5.2 Scope of the Study 1.15
1.5.3 Plan of Work 1.16
1.5.4 Components included in the Study 1.17
1.5.4.1 Coastal Waster Environment 1.17
1.5.4.2 Marine Environment 1.17
1.5.4.3 Land Environment 1.18
1.5.4.4 Biological Environment 1.18
1.5.4.5 Socio-Economic and Health Environment 1.19
1.5.4.6 Ecological Risks 1.19
1.5.5 Environmental Management Plan 1.20
1.6 Techno-economic Viability 1.20
1.6.1 Traffic Potential 1.20
1.6.2 Alignment of Canal 1.20
1.6.3 Dredging and Disposal Areas 1.21
1.6.4 Cost Estimates and Economic Viability 1.21
1.7 Permits and Approvals 1.21
Figures 1.1-1.3 1.22-1.24
Table 2.1 1.25
2. Proposed Project and Oceanographic Environmental Setting 2.1-2. 104
2.1 Proposed Project 2.1

2.2 Oceanographic Status in Project area along Route Alignment 2.2

Item Page
No.
2.2.1 Waves 2.2
2.2.1.1 Wave Measurement 2.3
2.2.1.2 Wave Refraction 2.4
2.2.1.3 Wave Period 2.5
2.2.2 Tides and Currents 2.5
2.2.2.1 Longshore Currents 2.5
2.2.2.2 Currents Studies 2.7
2.2.3 Sediment Transport 2.12
2.2.3.1 Longshore Sediment Transport 2.13
2.2.3.2 Spit Configuration 2.22
2.2.4 Geological Strata along Navigational Channel in 2.23
Adams Bridge Area
2.2.5 Bathymetry and Shallow Seismic Survey in 2.25
Gulf of Mannar and Palk Bay Area
2.2.5.1 Bathymetry and Shallow Seismic Survey in
Area Identified for Channel in Adam's Bridge 2.26
2.2.5.2 Bathymetry Survey of Area of 4 km. X 4 km. 2.36
2.2.5.3 Bathymetry and Seismic Survey along the
Channel in Palk Bay Area 2.37
2.2.6 Selection of Route in Adam's Bridge Area 2.38
2.2.7 Navigation Route in Palk Bay and Palk Strait 2.38
2.2.8 Computation of Dredged Material 2.38
2.3 Environmental Setting in Project Area 2.39
Figures 2.1-2.51 2.44-2.98
Tables 2.1 - 2.6 2.99-2.104
3. Marine Environment 3.1-3.167
3.1 Physico-chemical Characteristics 3.1
3.2 Biological Characteristics 3.3
3.3 Biodiversity of Islands in Study Region 3.32
3.3.1 Mandapam Group 3.32
3.3.1.1 Shingle Island 3.35
3.3.1.2 Krusadai Island 3.35
3.3.1.3 Pullivasal and Poomarichan Island 3.36

3.3.1.4 Manoli and Manoliputti Islands 3.38
3.3.1.5 Musal Island 3.39
Item Page
No.
3.3.2 Marine Organisms Observed around the
Mandapam Group of Island 3.40
3.3.3 Trend of Fish Catch in Mandapam Region 3.42
3.3.4 Keezhakarai Group 3.42
3.3.4.1 Mulli Island 3.43
3.3.4.2 Valai and Talairi Islands 3.44
3.3.4.3 Appa Island 3.45
3.3.4.4 Anaipar Island 3.46
3.3.5 Marine organisms recorded around Keezhakarai
Group Islands 3.47
3.3.6 Vembar Group 3.48
3.3.6.1 Nallathanni Island 3.49
3.3.6.2 Pulivinichalli Island 3.49
3.3.6.3 Upputhanni Island 3.50
3.3.7 Marine Organisms around Vember Group of Islands 3.51
3.3.8 Tuticorin Group 3.52
3.5.8.1 Karaichalli Island 3.53
3.3.8.2 Vilanguchalli Island 3.53
3.5.8.3 Kasuwar Island 3.54
3.3.9 Marine Organisms 3.55
3.4 Palk Bay/Palk Strait 3.56
3.4.1 Marine Water Quality 3.56
3.4.2 Biological Productivity 3.56
3.4.2.1 Primary Productivity 3.57
3.4.2.2 Secondary Productivity 3.59
3.4.2.3 Tertiary Productivity 3.61
3.4.2.4 Benthos 3.61
3.4.3 Sponges and Corals 3.62
3.4.4 Fishing in Palk Bay 3.64
3.4.5 Marine Mammals 3.64
3.4.6 Distribution of Palk Bay Reef 3.65
3.4.7 Review of the Coral Reef Ecosystem of Palk Bay 3.66
3.4.8 Present Status of Palk Bay 3.69
3.4.9 Wildlife Sanctuary Adjoining Palk Strait 3.70

3.5 Gulf of Mannar 3.72
3.6 Issues Related to Coral Reefs 3.73
3.6.1 Natural Stresses to Coral Reefs 3.74
3.6.2 Impacts of Human Activity on Coral Reefs 3.75
Item Page
No.
3.6.2.1 Sedimentation 3.76
3.6.2.2 Runoff/Chemical Pollution/ Water Quality 3.77
3.6.2.3 Sewage 3.78
3.6.2.4 Temperature Stress and Bleaching 3.79
3.6.2.5 Coral diseases 3.80
3.6.2.6 Destructive fishing practices 3.80
3.7 Impacts in Palk Bay and Gulf of Mannar 3.82
3.8 Conservation 3.83
3.9 Future Direction 3.84
3.10 Strategies for Coral Reef Ecosystems in India 3.85
3.10.1 Analyzing the Short Comings in Coral Reef
Conservation in India 3.85
3.10.2 Understand the Coral Reef Problems 3.85
3.10.3 Determine the True Economic Value of Coral Reefs in India 3.85
3.10.4 Coral Reef Conservation Education 3.87
3.10.5 Focus Management of Coral Reef around the Stakeholder 3.87
3.10.6 Incorporate More Coral Reefs in Marine Protected Areas 3.87
3.10.7 Control Managing Practices 3.88
3.10.8 Promote Sustainable Uses 3.89
3.10.9 Monitor the Effectiveness of Coral Reef
Management in India 3.89
Figures 3.1-3.18 3.92-3.109
Tables 3.1-3.46 3.110-3.167
4. Land Environment 4.1 - 4.15
4.1 Objectives 4.1
4.2 Data Used 4.2
4.3 Hardware and Software Used 4.3
4.4 Selection of Study Sites 4.3
4.5 Methodology 4.4
4.6 Data Interpretation 4.6
4.7 Identification of Dumping Sites for Dredged Materials 4.8
Plates 4.1-4.4 4.10-4.13
Tables 4.1-4.2 4.14-4.15

5. Socio-economic Environment 5.1 - 5.19
5.1 Socio-economics of the Fishing Community 5.1
5.2 Sample Survey 5.3
5.3 Existing Status 5.6
Tables 5.1 - 5.3 5.13-5.19
Item Page
No.
6. Assessment of Environmental Impacts 6.1-6.77
6.1 General 6.1
6.2 Impact Networks 6.1
6.3 Impacts due to Land Based Facilities 6.2
6.4 Impacts due to Dredging 6.3
6.4.1 Dredged Material Disposal 6.7
6.4.1.1 Disposal on Land 6.7
6.4.1.2 Disposal in Sea 6.8
6.5 Impacts due to Road and Rail Traffic 6.12
6.6 Impacts on Productivity and Ecology in GOM/Palk Bay 6.12
6.7 Impacts on Hydrodynamic Conditions 6.15
6.7.1 Tidal Current Distributions – Before and After Dredging 6.16
6.7.2 The Salient Conclusions 6.18
6.7.2.1 Gulf of Mannar 6.18
6.7.2.2 Palk Bay 6.18
6.8 Socio-economic Impact 6.19
6.9 Analysis of Alternatives for Route Alignment 6.19
Figures 6.1-6.30 6.23-6.58
Tables 6.1 - 6.11 6.59-6.76
7. Environmental Management Plan 7.1-7.9
7.1 Construction Phase 7.1
7.1.1 Acquisition of Land for Onshore Facilities 7.1
7.1.2 Dredging Activity 7.1
7.2 Operational Phase 7.3
7.2.1 Route Alignment 7.3
7.2.2 Discharges from Ships 7.3
7.2.3 Maintenance Dredging 7.5

7.3 Summary of Environmental Management Plan 7.6
7.3.1 Construction Phase 7.6
7.3.2 Operational Phase 7.7
8. Bibliography 8.1-8.7
List of Figures
Figure No. Title Page
No.
1.1 Shipping Routes in East Coast of India 1.22
1.2 The Gulf of Mannar and Palk Bay/Palk Strait Area 1.23
1.3 The Study Area 1.24
2.1 Measured Significant Wave Height 2.44
2.2 Measured Maximum Wave Height 2.44
2.3 Wave Refraction Between Tuticorin and Arimunai (NE Monsoon) 2.45
2.4 Wave Refraction Between Tuticorin and Arimunai (SW Monsoon) 2.46
2.5 Wave Refraction Between Tuticorin and Arimunai (SW Monsoon) 2.47
2.6 Wave Refraction Between Arimunai and Vedaraniyam 2.48 (NE Monso
2.7 Variation of Currents Off Arimunai in SW Monsoon 2.49
2.8 Components of Currents Near Surface off Arimunai
(Stn. C1) during Southwest Monsoon 2.50
2.9 Components of Currents near Bottom Off Arimunai (Stn. C1)
during Southwest Monsoon 2.51
2.10 Variation of Currents off Uthalai (GM)in SW Monsoon 2.52
2.11 Components of Currents near Surface off Rameswaram Island
South (Stn. C2) (GM) during Southwest Monsoon 2.53
2.12 Components of Currents near Bottom off Rameswaram Island
South (Stn. C2) (GM) during Southwest Monsoon 2.54
2.13 Variation of Currents off Pamban Pass in SW Monsoon 2.55

2.14 Components of Currents near Surface off Pamban Pass
(Stn. C3) during Southwest Monsoon 2.56
2.15 Variation of Currents off Tharuvai in SW Monsoon 2.57
2.16 Components of Currents near Bottom off Tharuvai
(Stn. C4) during Southwest Monsoon 2.58
2.17 Variation of Currents off Arimunai in NE Monsoon 2.59
2.18 Components of Currents near Surface off Arimunai (Stn. C1)
during Northeast Monsoon 2.60
Figure No. Title Page
No.
2.19 Components of Currents near Bottom off Arimunai (Stn. C1)
during Northeast Monsoon 2.61
2.20 Variation of Currents Uthalai (GM) in NE Monsoon 2.62
2.21 Components of Currents near Surface off Rameswaram Island
South (Stn. C2) (GM) during Northeast Monsoon 2.63
2.22 Components of Currents near Bottom off Rameswaram Island
South (Stn. C2) (GM) during Northeast Monsoon 2.64
2.23 Variation of Currents off Pamban Pass in NE Monsoon 2.65
2.24 Components of Currents near Surface off Pamban
Pass (Stn. C3) during Northeast Monsoon 2.66
2.25 Variation of Currents off Tharuvai in NE Monsoon 2.67
2.26 Components of Currents near Surface off Tharuvai (Stn. C4)
during Northeast Monsoon 2.68
2.27 Components of Currents near Bottom off Tharuvai (Stn. C4)
during Northeast Monsoon 2.69
2.28 Variation of Currents off Arimunai in FW Period 2.70
2.29 Components of Currents near Surface off
Arippumunai (Stn. C1) during Fair Weather 2.71
2.30 Components of Currents near Bottom off
Arrippumunai (Stn. C1) during Fair Weather 2.72
2.31 Variation of Currents off Uthalai (GM) in FW Period 2.73
2.32 Components of Currents Near Surface off Rameswaram
Island South (Stn. C2) (GM) during Fair Weather 2.74

2.33 Components of Currents near Bottom off Rameswaram
Island South (Stn. C2) (GM) during Fair Weather 2.75
2.34 Variation of Currents off Pamban Pass in FW Period 2.76
2.35 Components of Currents near Surface off Pamban
Pass (Stn. C3) during Fair Weather 2.77
2.36 Monthly Sediment Transport Rate 2.78
2.37 Monthly Sediment Transport Rate 2.79
2.38 Monthly Sediment Transport Rate 2.80
2.39 Annual Net Sediment Transport Rate 2.81
Figure No. Title Page
No.
2.40 Annual Gross Sediment Transport Rate 2.82
2.41 Location of Boreholes 2.83
2.42a Grain Size Distribution at BH1 at Surface and 2.5 m 2.84
2.42b Grain Size Distribution at BH1 at 5.0 m and 7.5 m 2.85
2.42c Grain Size Distribution at BH1 at 9.0 m and 12 m 2.86
2.43a Grain Size Distribution at BH2 at Surface and 2.5 m 2.87
2.43b Grain Size Distribution at BH2 at 5 m and 6.5 m 2.88
2.43c Grain Size Distribution at BH2 at 11 m 2.89
2.44a Grain Size Distribution at BH3 at Surface and 0.7 m to 8.5 m 2.90
2.44b Grain Size Distribution at BH3 at 8.5 m to 10 m and 10.5 to 12.7 m 2.91
2.45 Bathymetry Map of Gulf of Mannar (1975) 2.92
2.46 Bathymetry map of Tuticorin Coastal Region (1999) 2.93
2.47 Location of Proposed Site 2.94
2.48 Bathymetry Study Over 100 Line km Across the 20 km x 4 km line 2.95
2.49 Area Showing Bathymetry More than 12 m and
Hard Strata in Palk Bay Area 2.96
2.50 Area Showing Bathymetry more than 10 m with
Hard Strata at about 16 m depth in Palk Bay Area 2.97
2.51 Bathymetry along the Proposed Channel 2.98

3.1 Data Locations 3.92
3.2 Variation in Salinity 3.93
3.3 Variation in Salinity and Silicate 3.94
3.4 Particle Size Distribution of Sediments (1-10 Sampling Stations) 3.95
3.5 Trophic Relations of Marine in Study Area of
Sethu Samudram Ship Canal Project 3.96
3.6 Maximum Diversity Index values of Phytoplankton in 21 Islands
of Gulf of Mannar 3.97
3.7 Maximum Diversity Index values of Zooplanktons in 21 Islands of
Gulf of Mannar 3.98

Figure No. Title Page
No.
3.8 Location of Corals in the Gulf of Mannar and the Palk Bay 3.99
3.9 Coral Reef and Seagrass Areas around the Islands of
Gulf of Mannar 3.100
3.10 Maximum Diversity Index values of Corals in 21 Islands of
Gulf of Mannar 3.101
3.11 Locations of Pearl Banks in the Gulf of Mannar 3.102
3.12 Chank Habitats in the Gulf of Mannar and the Palk Bay 3.103
3.13 Habitats of Sea Cow (Dugong-dugong) in the Gulf of Mannar
and the Palk Bay 3.104
3.14 Habitats of Sea Weed, Sea Grass and Holothuria in the
Gulf of Mannar and the Palk Bay 3.105
3.15 Maximum Diversity Index values of Seagrass in 21 Islands of
Gulf of Mannar 3.106
3.16 Maximum Diversity Index values of Mangroves in 21 Islands of
Gulf of Mannar 3.107
3.17 Locations of Mangroves in Gulf of Mannar and the Palk Bay 3.108
3.18 Maximum Diversity Index values of Corals, Mangroves and
Seagrass in 21 islands of Gulf of Mannar 3.109
6 .1 Environmental Impact Network - Construction Phase 6.23
6.2 Environmental Impact Network - Post-Construction/
Operation Phase 6.24
6.3 Study Area for Route Alignment in Adam’s Bridge Area 6.25
6.4 Borehole Data in Adam’s Bridge Area 6.26
6.5 Bathymetry Along Line 1 6.27
6.6 Bathymetry Along Line 2 6.28
6.7 Bathymetry Along Line 3 6.29
6.8 Bathymetry Along Line 4 6.30
6.9 Bathymetry Along Line 5 6.31
6.10 Quantity Dredged Material along Various Tracks in Adam’s Bridge 6.32
6.11 The Alignment of the Proposed Channel 6.33

6.12 Bathymetry along the Proposed Channel 6.34
Figure No. Title Page
No.
6.13 Cross Section of Proposed Channel 6.35
6.14 3D Plume of Disposed Silt 6.36
6.15 Near Field 6.37
6.16 Far Field 6.38
6.17 Central Line Dilution 6.39
6.18 Geographical Domain Considered for Modelling 6.40
6.19 Locations for Current Measurements 6.41
6.20 Tidal Stream Observations 6.42
6.21 Tidal Stream Observation 6.46
6.22 Tidal Observations 6.50
6.23 Proposed Ship Navigation Alignment Considered for Modelling 6.51
6.24 Calibration Tide Heights 6.52
6.25 Calibration Currents 6.53
6.26 Spatial Current Predicted by the Model - Before Dredging 6.54
6.27 Spatial Current Predicted by the Model - After Dredging 6.55
6.28 Locations of Coral Reefs in the Modelling Domain
(Adjoining Mandapam and Pambam Islands) 6.56
6.29 Locations of Coral Reefs in the Modelling Domain
(Dhanushkodi Portion of Pambam Island) 6.57
6.30 Plan Showing Various Alignments of Sethusamudram Ship Canal
Project and the Group of Islands (Marine Parks) in Gulf of Mannar 6.58

List of Tables
Table No. Title Page
No.
1.1 Texture, Mineralogy and Elemental Composition of
Sediments in Palk Strait 1.25
2.1 Monthly Variation of Breaking Wave Height (m) 2.99
2.2 Monthly Variation of Wave Period (s) 2.100
2.3 Predominant Wave Characteristics Buoy Data Off
Vembar from Wave Rider 2.101
2.4 Monthly Variation of Longshore Current (m/s) 2.102
2.5 Longshore Sediment Transport Rate 2.103
2.6 List of Islands in the Gulf of Mannar 2.104
3.1 Particulars of Sampling Locations along the
Proposed Canal Alignment 3.110
3.2 Physico-chemical Quality of Marine Water 3.111
3.3 Marine Water Quality (Inorganic, Nutrient and Heavy Metals) 3.112
3.4 Sediment Quality 3.113
3.5 Gross Primary Productivity 3.115
3.6 Number of Species Recorded in the Gulf of Mannar Marine
Biosphere Reserve during Different Periods 3.116
3.7 Status Report of Biota of Gulf of Mannar 3.117
3.8 Distribution of Phytoplankton in Gulf of Mannar
(Number of Species Recorded During October '98, August '99) 3.124
3.9 Maximum Diversity Index Values of Phytoplankton
in 21 Islands of Gulf of Mannar 3.125
3.10 Enumeration and Diversity of Phytoplankton 3.126
3.11 List of Phytoplankton Recorded 3.127
3.12 Distribution of Zooplankton in Gulf of Mannar (Number of Species
Recorded During October '98, August '99) 3.128
3.13 Shannon Weaver Diversity Indice of Zooplankton Recorded
at various Coastal Waters in India 3.129
3.14 Enumeration and Diversity of Zooplankton 3.130

3.15 List of Zoolplankton at Different Locations 3.131
Table No. Title Page
No.
3.16 Maximum diversity index values of Zooplankton in 21 island
3.17 Distribution of Benthic Organisms in Gulf of Mannar 3.133
3.18 Enumeration and Diversity of Macrobenthos 3.134
3.19 List of Macrobenthos Recorded 3.135
3.20 Density and Biomass of Meiofauna in Sediment Samples 3.138
3.21 Distribution Pattern of Corals, Live Corals (Percentage)
and Seagrases 3.139
3.22 Maximum diversity index values of Corals in 21 island
3.23 List of Fishlanding Centres within
Sethusamudram Ship Canal Zone 3.141
3.24 Shannon Weaver Diversity Index (H' value) for the Ornamental
Fishes Recorded Around each Island in the Gulf of Mannar 3.143
3.25 Commercially Important Species Contributing to Fishery in the Gulf of
3.26 Major Fishing Gears used in the Gulf of Mannar and the Palk Bay 3.145
3.27 Marine Fish landings in the Gulf of
Mannar during 1992-96 (In Tonnes) 3.146
3.28 Composition of Different Groups in Marine Fish Landings in
the Gulf of Mannar (Catch in Tonnes) 3.147
3.29 Composition of Trawl Catches in the Gulf of Mannar 3.149
3.30 Composition of the Trawl Catches at
Pamban, Rameswaram and Tuticorin 3.150
3.31 Pearl Oyster Paars in the Gulf of Mannar and the Palk Bay 3.151
3.32 Distribution of Seagrass in the Islands of Gulf of Mannar 3.152
3.33 Maximum diversity index values of Seagrass in 21 island
3.34 Maximum diversity index values of Mangroves in 21 island
3.35 Mangrove Species in Coasts of Palk Bay and Gulf of Mannar 3.155
3.36 Distribution of Mangrove Vegetation in the
Islands of Gulf of Mannar 3.156

Table No. Title Page
No.
3.37 Annual Primary Productivity (Gross) in Certain Marine
Environments as Grams Carbon per square meter Sea Surface 3.157
3.38 Coral Fauna around the Mandapam Group of Islands 3.158
3.39 Summary of Underwater Observations on Shelter and
Food of Various Coral Reef Associated Fauna in the
Mandapam Group of Islands 3.159
Marine Water Quality in Palk Bay (Latitude 9O44’)
3.40 3.160
3.41 Distribution of Zooplankton in Palk Bay near the Proposed Channel 3.161
3.42 Distribution of Decapods in Palk Bay 3.162
3.43 Distribution of Desmospongiae and Corals in Palk Bay 3.163
3.44 Distribution (kg/hr) of Various Fishery Resources along
Palk Bay SE Coast of India during 1985-90 3.165
3.45 Abundance of Demersal Finfish Resources (kg/hr) in
SE Coast of India EEZ 3.166
3.46 Perches Abundance in kg along S.E. Coast (Palk Bay) 3.167
4.1 Land use/Land cover Status in Pamban Island, Based on the
Satellite data of May, 2002 4.14
4.2 Land use/Land cover Classification System 4.15
5.1 Summary of Coastal Villages/Towns in the Study Area 5.13
5.2 Details of Coastal Towns/Villages in the Study Area (Palk Bay) 5.14
5.3 Details of Coastal Towns Villages in the Study Area 5.18
6.1 Bathymetry along Line: 1 6.59
6.2 Bathymetry along Line: 2 6.60
6.3 Bathymetry along Line: 3 6.61
6.4 Bathymetry along Line: 4 6.62
6.5 Bathymetry along Line: 5 6.63
6.6 Dredging Requirement for 10 m Depth (9.15 m draught)
and 300 m Width Channel 6.64
6.7 Dredging Requirement of 12 m Depth (10.7 m draught)
and 300 m Width Channel 6.65

6.8 The Quantity of Dredged Material for 14 m Deep 500 Wide Channel 6.66
Table No. Title Page
No.
6.9 Expected Number of Transits through Sethusamudram Channel 6.67
6.10 Inputs to Model for Dredged Material Disposal (12 m deep channel) 6.68
6.11 Maximum and Minimum Tidal Current (Speed) at Locations in
Palk Bay and Gulf of Mannar 6.69
6.12 Speed and Direction of Currents for Patch-I - Before Dredging 6.70
6.13 Speed and Direction of Currents for Patch-II - Before Dredging 6.72
6.14 Speed and Direction of Currents for Patch-III - Before Dredging 6.74
6.15 Speed and Direction of Currents for Patch-IV - Before Dredging 6.76

List of Plates
Plate No. Title Page
No.
4.1 Merged FCC (IRS 1D PAN Sharpened LISS III) depicting
Pamban Island 4.10
4.2 Merged Imagery (LISS III + PAN) depicting Western Surrounds
of Sethusamudram Ship (Navigational) Canal route in Indian Water 4.11
4.3 Land Use/Land Cover Status in Pamban Island based on IRS 1D 4.12
(LISS III + PAN), May, 2002
4.4 Merged Data (PAN + LISS III) depicting degraded land, selected
for dumping dredged material in Pamban Island 4.13

List of Drawings
Drawing No. Title
2.1 General Bathymetry in Palk Bay
2.2 Bathymetry and Shallow Seismic Survey - South of
Adam’s Bridge Line 1
2.3 Bathymetry and Shallow Seismic Survey - South of
Adam’s Bridge Line 2
2.4 Bathymetry and Shallow Seismic Survey - South of
Adam’s Bridge Line 3
2.5 Bathymetry and Shallow Seismic Survey - South of
Adam’s Bridge Line 4
2.6 Bathymetry and Shallow Seismic Survey - South of
Adam’s Bridge Line 5
2.7 Bathymetry and Shallow Seismic Survey - North of
Adam’s Bridge Line 1
2.8 Bathymetry and Shallow Seismic Survey - North of
Adam’s Bridge Line 2
2.9 Bathymetry and Shallow Seismic Survey - North of
Adam’s Bridge Line 3
2.10 Bathymetry and Shallow Seismic Survey - North of
Adam’s Bridge Line 4
2.11 Bathymetry and Shallow Seismic Survey - North of
Adam’s Bridge Line 5
2.12 Bathymetry Survey in Palk Bay along Proposed Channel Alignment

1. Introduction
1.1 Preamble
Shipping plays a vital role in the development of the Indian Economy as the
country has been gifted with a peninsular coastline of about 6,000 km, which is
studded with 12 major and over 150 intermediary and minor ports. It also has a
strategic location as one of the world's main sea routes and thus has a history of
maritime trade with countries across the globe.
It is, however, unfortunate that despite having such a coastline India does not
have, within her own territorial waters, a continuous navigable sea route around the
peninsula from the Gulf of Mannar to Palk Bay and vice-versa due to the presence of
shallow (about 3 m) sand-stone reef called 'Adam's Bridge' at Pamban near
Rameswaram between the south-eastern coast of India and Talaimann on the western
coast of Sri Lanka. Consequently, the entire coastal traffic from the east coast of the
country to the west and vice-versa has to go around Sri Lanka entailing an additional
distance of more than 254-424 nautical miles and 21-36 hours of sailing time. The
shipping routes and savings are shown in Fig. 1.1.
The Gulf of Mannar, an inlet to the Indian Ocean between south-eastern India
and western Sri Lanka, is bounded on the north-east by the island of Rameswaram,
Adam's Bridge and Mannar. The Gulf is about 130-275 km wide and 160 km in length.
The Palk Bay on the north of Gulf of Mannar is about
64-137 km wide and 137 km long and includes many islands of Sri Lanka.
Furthermore, Adam's Bridge is a chain of shoals, nearly seven in all, located between
India and Sri Lanka separating Palk Bay and Gulf of Mannar. It is about 30 km long
and the sea across this portion is shallow with a depth of about
3-3.5 m only during high tides.
Various committees that have deliberated the subject have observed that a
shorter route through the Palk Bay is an important necessity to save time and foreign
exchange spent on import of fuel for Indian ships, also the country can stand to gain
revenue in foreign currency due to toll collections from International ships.

The creation of a channel called \"Sethusamudram Ship Channel \", now under
consideration of the Ministry of Shipping, Government of India, envisages construction
of channel in stages and of varying lengths to suit different drafts ranging from 9.15 m
to 12.8 m through dredging / excavation across the Adam's Bridge. It is proposed to
study different alignments for the proposed channel in the light of representations from
the public, the fisherman, the pilgrims and above all its techno-economic viability. The
channel will originate from Tuticorin Harbour, extend north-east upto south of Pamban
island, cut through Adams Bridge and proceed parallel to medial line of fishing
between Sri Lanka and India before joining the Bay of Bengal channel. The width of
channel will vary between 200 and 500 m and will require dredging to arrive at desired
depth in the Adams Bridge and Palk Bay area. In GOM navigation depths will be used
hence no dredging is required. The area engulfing the Adam’s Bridge known as
‘Sethusamudram’ has been derived from the Kings of Jaffna who were called
'Sethukavalar,' meaning protectors of Adam's Bridge and the Southern sea that
surrounds the region. The Gulf of Mannar and Palk Bay/Palk Strait separated by
Adam's Bridge are shown in Fig. 1.2.
The proposed channel on commissioning will bring plenty of prosperity and
industrial growth in the Indian hinterland lying along the proposed ship channel and
the very presence of the short route would increase the turn-arounds of the coastal
and international vessels. There are many other benefits which are difficult to quantify
like (a) surge in the development of coastal trade,
(b) development of Industries in Ramanathapuram and Tuticorin Districts,
(c) amelioration of distress due to droughts visiting annually Ramanathapuram and
Tuticorin Districts.
• The project will further enable direct movement of Indian naval fleet between
the east and west coast of the country instead of going around Sri Lanka.
• The project opens up minor ports all along Tamil Nadu coastline upto the
major port of Tuticorin and further west upto Colachal.
The Tuticorin Port Trust, the nodal agency identified by the Ministry of
Shipping for the implementation of the proposal has retained in July 2002 the National
Environmental Engineering Research Institute (NEERI), Nagpur to conduct

Environmental Impact Assessment studies followed by the Techno-Economic Viability
for the proposed \"Sethusamudram Ship Channel Project\".
1.2 Earlier Studies Involving Creation of Canal
One of the pioneering efforts undertaken to study the construction of the
canal was the Commander Taylor's proposal of 1860. Although a series of proposals
on the subject were forwarded thereafter during the British regime in the country, due
consideration could never be given to the proposal and the Sethusamudram Ship
Canal remained a dream for the Indian maritime community.
After Independence, the Government of India continued to pursue the idea of
constructing the Sethusamudram Ship Canal and among the many committees
constituted for studying the feasibility of the project, the 'Ramaswamy Mudaliar
Committee' constituted in 1955, was the first. In addition to studying the feasibility of
the Sethusamudram Ship Canal project, the committee also studied the increase in
potentiality of the port of Tuticorin, if it were to be developed into a deep-sea port
alongwith the canal. Although Tuticorin port was in existence for a long time, it did not
have berthing facilities for ships and those had to be attended at the anchorage, which
was about 5 to 6 miles off the coast.
The committee was of the view that the two projects namely the
Sethusamudram Ship Canal and Tuticorin Harbour were closely inter-related and
should be taken up and executed as part of the same project. After evaluating the
costs and benefits, the project was found to be feasible and viable and the committee,
therefore, proposed an initial capital outlay of Rs. 998 lakhs for the integrated
Sethusamudram-cum-Tuticorin Port Scheme. Thereafter, series of studies were
undertaken for the project, and many of those recommended for increase in draught
from the original 26 ft. proposed by the Ramaswamy Mudaliar Committee. These
studies also led to revision of the Project cost, as also to the expected savings in
navigable distance resulting from the canal which ranged from 260 to 425 kilometres.
Finally, the Tuticorin Harbour project was sanctioned in 1963 and the Government of
India continued to study the various aspects of the Sethusamudram Ship Canal
Project.
Over a last century, several proposals were formulated by various
committees to create a continuous navigable route all around the peninsula within the

territorial waters of India. The latest study of the project was undertaken by the
Lakshminarayanan Committee constituted by the Ministry of Shipping and Transport
(Port wing) in 1981. The Committee, after a critical review of the earlier proposals,
some of which envisaged the canal project by cutting across the main land,
investigated another alignment known as the 'K' alignment across the Rameswaram
island near Kodandaramasamy temple, and established the technical feasibility and
economic viability of the alignment. This alignment was also in keeping with the
representations of the public, the fishermen and the pilgrims of Ramanathapuram area
who preferred the island being cut east of Rameswaram town. The Committee fixed
the alignment across the land and along the northern and southern approaches in the
sea, conducted drilling operations in sea and on land, collected tidal, current, wind and
other meteorological data, and submitted to the Government of India in 1983 a project
feasibility report with an estimated project cost of Rs. 282 crores including foreign
exchange component of Rs. 3 crores. As per economic analysis by the Committee, the
project would have generated surplus from twentieth year of its operations building up
cumulative surplus of Rs. 453 crores at the end of twenty fifth year. However, no
follow-up action on this report was initiated due to financial constraints.
In its pursuit to make the Sethusamudram Ship Canal project a reality
the Government of Tamilnadu in 1996 got, through Pallavan Transport Consultancy
Services (PTCS) Limited, the Lakshaminarayanan Committee proposal updated for its
economic viability with a view to seeking approval from Government of India for the
project. Fresh particulars of cost and traffic were collected and incorporated in the
report so as to reflect conditions as of 1996.
Apart from the construction of proposed canal, which constituted the major
component of project, creation of number of other infrastructural facilities as listed
below were envisaged :
• Construction of a \"lock\"
• Construction of rubble mound type breakwaters on either sides of the
canal
• Navigational aids
- Lighted beacons/buoys
- Racons

- Satellite based differential global system
- Improvements to Pamban light house
• Flotilla
- Harbour tugs
- Pilot, mooring, survey-cum-lighting launches
- Despatch vessels
• Shore facilities
- Two service jetties
- Slipways
- Buoy yard
- Repair workshop
• Staff and administration buildings
The canal proposed had two legs, one near the Point Calimere called
the Bay of Bengal Channel and another across the narrow Danushkody Peninsula
near Kodandaramasamy Temple. The Bay of Bengal Channel traverses the Palk Bay
wherein the sea-bed is mostly soft to hard clayey-sand in nature and not corals or
rock. The channel proposed was 19.3 km away from Point Calimere and Kanakesan
Thurai where the coast consists of only clayey-sand. The second leg of the canal 802
m long would have crossed the narrow Danushkody Peninsula through the land
portion. The entire coast of Danushkody Peninsula on the North and the South is all
sandy. In the North Approach Channel, soft sand-stone was met with below 12 m
depth and cutting this sand-stone was not necessary even in the ultimate stage of the
canal. The canal would have, however, cut the road connecting Rameswaram and
Danushkody. This road is being used by the Rameswaram fisherman to go to
Danushkody for daily fishing as there is no habitation at Danushkody. The project
envisaged a high-level or a swinging bridge at the crossing point to enable the traffic to
go through. Tracer studies conducted at two places along the 'K' alignment
established that the pattern of movement of sea-bed silt would almost be in the same
direction as that of the proposed canal, and that the chances of siltation would be very
minimal.
The cost estimates for the proposed canal project were worked out by PTCS
Ltd. based on the same quantities of dredging as in the 1983 report but with updated
rates for the year 1996. The costs of dredging for various segments of channel for

three different drafts viz. 30, 31 and 35 feet were worked out alongwith cost estimates
for other components of the project including those of navigational aids and floating
crafts. The construction period for 31 feet draft was estimated as four years with a
capital expenditure of Rs. 760 crores. The operation and maintenance cost was
estimated by PTCS Ltd. at Rs. 4.52 crores per year.
An economic appraisal of the Sethusamudram Ship Canal project, taking into
account cost estimates and cost benefits of the proposal, were made by PTCS Ltd.
Based on Net Present Value (NPV) method of appraisal, an Internal Rate of Return
(IRR) of 10 to 17% on the project investment was arrived at. Considering the then
interest rate of 9% per annum of government lending to ports on the capital employed
the project would have generated surplus from the 16 or 17th year of its operation, and
thereafter the benefits to the canal company would have been 47 crores in the first
year, and this would have increased to
100-120 crores every year.
The traffic potential through the canal at various draughts projected by both
the studies for 2000 AD were as follows :
Upto 30' draught 31~32' draught Above 32' draught
1983 Committee 2,100 2,200 2,300
1996 Report 3,791 3,875 4,211
Later a report was prepared by NEERI in 1998 comprising the examination of
environmental status of the project region based on information available on
hydrography, marine water quality and ecological resources etc. An environmental
impact study was recommended by NEERI as essential for fuller description and
appreciation of the natural processes occurring in the region to delineate the
environmental consequences including the ecological risks associated due to the ship
canal and suggest measures for minimisation and mitigation of potential adverse
impacts.
The study for initial environmental examination of proposed canal also
recommended that the canal route should pass through Adams Bridge area
circumventing the Pamban Island instead of cutting through it. A detour was
suggested from earlier alignment. Keeping in view the location biosphere reserves, it
was suggested that an environmental viable alignment of route be selected in GOM so
that proper distance from Biosphere reserves can be maintained and the available

navigational route can be selected based on both environmental and technical
viability. The EIA studies recommended in IEE report of NEERI was therefore
subjected to proper scoping so that all the environmental concerns due to this project
can be addressed and resolved through this report. The technical viability would
depend on quantity of dredging required in the vicinity of Adams Bridge area keeping
in view the draft required to operate the channel. This study report addresses
environmental, technical and commercial viability of the proposed ship canal project.
1.3 Project Region
The Palk Bay and the Gulf of Mannar together sprawling over an area of
10,500 sq.km (8O35’N to 9O25’N latitude and 78O8’E to 79O30’E longitude) in which the
ship channel is proposed to be constructed are biologically rich and rated as the highly
productive seas of the world and their biodiversity is considered globally significant. In
the Gulf of Mannar, there are 21 islands covering an area of 623 ha which have been
declared as National Marine Parks by the Tamilnadu Forest Department and the
MoEF, Government of India. The islands are distributed in 4 groups namely
Mandapam, Keezhakarai, Vembar and Tuticorin group.
The islands have luxurient growth of mangroves in their shores and swampy
regions. The coral reef of fringing and patch type are present around the 21 islands
from Rameshwaram to Tuticorin covering a distance of 140 km. However, a major part
of the reef is fringing type arising from shallow sea floor of not more than 5 m in depth.
About 3600 species of flora and fauna have been recorded in this area. Fringing type
of reef is present in Palk Bay.
The hydrography data shows that there are two circulations of water masses
in the region, the clockwise circulation of south-west monsoon and the counter
clockwise circulation of north-east monsoon. The reported current velocities in the Palk
Bay and the Gulf of Mannar are as mild as 0.2 - 0.4 m/sec except on few days during
south-west monsoon when it rises upto 0.7 m/sec. The directions of currents follow the
directions of predominant winds.
The presence of corals along the proposed ship channel alignment is
negligible however occurrence of major groups of biological resources like sea fan,
sponges, pearl oysters, chanks and holothuroids at various locations have been
reported. All the three groups of prochordata organisms, considered as the connecting

link between invertebrates and vertebrates, viz., hemichordata, cephalochordata and
urochordata have been recorded mostly around the islands of the Gulf of Mannar.
There are 87 fish landing stations between the south of Point Calimere and
Pamban in the Palk Bay, and 40 stations in the Gulf of Mannar between Pamban and
Tuticorin. Out of over 600 varieties of fishes recorded in this area, 72 are commercially
important. During 1992-2001, the fish production has increased gradually from 55,300
tonnes in 1992 to 2,05,700 tonnes in 2001. Non-conventional fishing in the region is
represented by pearl, chank, sea weeds, ornamental shells and holothurians.
Rare and endangered species of sea turtle, dolphin, sea cow and whale are
recorded in the Gulf of Mannar and the Palk Bay. The sea cow inhabitates the shallow
shore regions where grasses occur, while other endangered animals mostly prefer
deep sea.
Several species of green algae, brown algae, red algae, blue-green algae and
sea grasses are recorded in the Gulf of Mannar and the Palk Bay. A few of the islands
are reported to possess patches of mangroves predominated by Avicennia sp. and
Rhizophora sp.
Most of the habitats of the sensitive biota, viz., corals, pearl oysters, chanks,
dugong, holothuroids and marine algae are along the coast and around the islands.
Along the coast in the Gulf of Mannar and the Palk Bay there are 138 villages
and towns spread over 5 districts.
1.4 Geomorphology of Study Region
The study region stretches between Tuticorin and Dhanushkoti including its
coastal and offshore water in Gulf of Mannar and Palk Bay area between Pumban and
Point Calimere.
The coastline near Tuticorin is extensively used due to the presence of major
port. Beach is very flat and narrow between Tuticorin and Sippikulam. Offshore islands
viz; Pandyan Tivu, Van Tivu, kasuvari Tivu, Vilangu Shuli Tivu and Kariya Shuli tivu
are present within 5 km distance from the coast line along this segment and offer
protection from wave action. The backshore of this costal segment largely consists of
salt pans. The Viappar river joins Gulf of Mannar near Sippikulam. An extensive
coastal low land is seen between Sippikulam and Vembar (Loveson, 1994).

The coastal segment between Sippikulam and Naripaiyur is open without any
offshore islands or submerged coral banks and is exposed to direct action of waves
both during southwest monsoon and northeast monsoon. The coastline near
Kannirajapuram is found with large extent of beach rocks with pear luster (Loveson,
1994). Wide and flat sandy beach with numerous small dunes are seen between
Naripaiyur and Mukkaiyur .
The formation of sand island off Tuticorin indicates this region as sediment
sinks with progressive accumulation of sand. The large beach storage of sand
between Manppad and Tiruchendur, Vembar and Valinokkam and Rameswaram
Island is an indication of depositional features of littoral sediments.
Gundar river joins the sea near Mukkaiyur. The presence of offshore islands
are once again noticed from Mukkaiyur till Mandapam. There are 16 islands noticed
along this coastal segment viz., Uppu Tivu, Shalli Tivu, Nalla Tanni Tivu, Anaipar Tivu,
Palliyarmunai Tivu, Puvarasanpatti Tivu, Appa Tivu, Talairi Tivu, Valai Tivu, Muli Tivu,
Musal Tivu, Manali Tivu, Pumorichan Tivu, Kursadi Tivu, Kovi Tivu, and Shingle Tivu.
The beaches between Mukkaiyur and Valinokkam are very wide with elevated dunes.
Extensively developed beach is seen at Kilamundal. Flat rocky shorelines are noticed
near Valinokkam (Loveson, 1994). Extensive spread of rocky shore with hard sand
stone platform is seen off Valinokkam. There is a Bay formation immediately on the
northern side of Valinokkam.
No beach is present especially during high tide Kilakarai. A narrow and flat
beach is noticed near Sethukarai with the abundance of algae along the coastline.
Loveson and Rajamanickam (1987, 1989) have identified a spit growth near
Pariyapattinam. They described well-developed hooked nature spit extending
southeast and connecting the main land in southwest direction. This formation of spit
extending southeast and connecting the main land in southwest direction indicated
seaward progradation of the coast between Tuticorin and Mandapam.
Wave cut cliff is seen at places like Valinokkam, Sethukarai and Mandapam.
Very low and narrow sandy beach is noticed between Kalimangundu and Vedalai
(loveson, 1994). Sea is found to be very calm in this region. Wave cut platform is once
again noticed along the coast of Vedalai. A patch of rocks is observed along the coast
between Mandapam camp and Mandapam tip. Agrawal (1988) observed that the area

between Mandapam tip and Pamban Island is attributed to a sand spit later emerging
as a high water land. The coastline between Mukkaiyur and Mandapam is totally
protected from northeast monsoon waves. Chandrasekar et al. (1993) indicated
reversal trend in the direction of sediment transport between Mandapam and Cape
Comorin due to change in the coastal configuration, deposition as the formation of
numerous spits along this coast that too, in a region where fluvial activities are
negligible. The presence of three offshore islands viz., Pumorichan Tivu, Kursadi Tivu,
Shingle Tivu are noticed off Rameswaram Island in Gulf of Mannar. The stretch of
shoreline around Rameswaram Island exhibits distinct variation (Loveson, 1994).
The central zone of the northern part of Rameswaram is made up of
undulatory sandy bodies with a relief upto 21 m above Mean Sea Level (MSL). This
area is partially covered with huge dunes. Northern part of Rameswaram Island is
occupied by raised coral plain. Characteristically, this zone is flat with dead corals and
numerous minor circular depressions. These depressions are liable to get filled with
water during rainy season and is entirely devoid of vegetation. Huge sand dues of
medium grain and white sands are found in the central part of the island. Dune
patterns are well developed by the active Aeolian processes, resulting in the migration
of dunes with frequent changes in their shapes and patterns from time to time but
generally trends due east to west. The sand sheet covers the southwestern zone of
the island. Within this unit, on the western part, localized sand mound of about 19 m
height is noted (Loveson, 1994). The beach zones in this area are broader with wide
inter tidal zones. The tail portion of Rameswaram occupying the southeastern part of
the island has coral swampy plain, which is considered to be of recent in age. This
vast flat and low-lying plain, which is considered to be of recent in age. This vast flat
and low lying plain is essentially composed of thin sheet of silt and clay materials in
which coral fragments are impregnated. Invariably, this zone is often inundated by
seawater during high tides, monsoons and storm seasons.
At east, a long sand spit of about 20 km length is formed up to Arimunai and it
tends to grow longer and wider. The width of this sand spit which is about
2 km near Uthalai, reduced to Arimunai and it tends to grow longer and wider. The
width of this sand spit which is about 2 km near Uthalai, reduced to 1250 m at
Mukkuperiyar, 750 at Dhanushkodi and 150 m at just east of Arimunai and coverages
on tip at Arimunai. The beach berm is found to be highly elevated along the sand spit

bordering Gulf of Mannar, but very low and flat along the side bordering Palk Bay.
There is a marked depression in the sand spit level between Palk Bay and Gulf of
Mannar between Dhanushkodi and Arimunai. Due to such level difference, the water
overflows during spring tide particularly from Bay carrying the fine sediment to the
backshore regions. Most of the time, the water is stagnant and remains along the
trough of the spit. This low lying region is fully occupied by water column during the
monsoon season.
The coastal process between Arimunai (India) and Talaimannar (Sri Lanka),
i.e. along Adman’s Bridge is quite complex which predominantly control the exchange
of sediment between Gulf of Mannar and Palk Bay. Adam’s Bridge is formation of
submerged sand shoals and there are around 17 islands present with bushes and
plants. The average length of these islands vary between 0.8 km to 3 km. This is
exposed to complex current pattern with the presence of quicksand. The currents near
Adam’s Bridge and Pamban Pass are found to be more seasonal. Submerged sand
shoals are seen shifting south of Arimunai and remain quasi-steady.
The nearshore on the northern side of the Rameswaram Island is found to be
very shallow causing the northeast monsoon waves to break far offshore. The coastal
stretch between Mandapam and Ariyaman in Palk Bay shows the presence of wide
beach with elevated dunes.
Loveson et.al. (1990) classified the coastal zone of Palk Bay into 3 groups; (i)
uplands/highlands with scantly vegetation, comprised of Cuddalore sandstone
formations, (ii) along the lower elevations sedimented Cuddalore sand stones, and (iii)
coastal lands mainly of microdeltas, swamps, and beach ridges based on the
geomorphological features. A large amount of sediments from those pediments are
removed constantly by rainfall and minor rivers. Because the pediments are placed
over the substratum which is appreciably sloping towards the sea, the erosion is found
to be intensive along the coastal islands. The eroded sediments brought to the littoral
zone are dumped in Palk Bay. As Palk Bay is shallow and protected from the high
waves and currents, the materials brought by these minor rivers is deposited in the
mouth of each river/stream, leading to the formation of micro-deltas in due course,
encouraging the formation of new shorelines.

Palk Bay is very shallow and is largely occupied by sand banks and shoals
(Agrawal, 1988). Abundant growth of corals, oysters, sponges, and other sea bottom
communities flourish in the relatively calm waters of Gulf of Mannar.
Sea level variations along the Tamilnadu coast were studied by Loveson et.al., (1990)
using satellite imageries and photographs. About 300 sediment samples were
collected along the central Tamilnadu coast by Chandrasekhar and Rajaminckham
(1993) and suggested to possibility of the supply from ultrabasic, pegmatitic and
granitic source of material to the depositional basic.
River Influx and Sedimentation in Palk Bay/Palk Strait
Vaigai River basin is located between latitude 9O15’ and 10O25’N and
longitude 77O15’ to 79O covering an aerial extent of 8600 sq. km. in the Madurai and
Ramanathapuram districts of Tamil Nadu, India. The river Uaigai, originates at an
altitude of 2200 m above mean sea level in the western ghats, drains through the
plains and confluences with the Bay of Bengal near Attangarai of Ramanathapuram
district. The basin is bounded by western ghats, in the west, Palni hills in the north, a
stretch of mountain ranges comprising Varushanad and Andipatti hills in the south and
the Bay of Bengal in the east.
Vellar estuary also comes under Palk Bay (lat. 11029'N ; long. 79046'E).
Sediment in estuarine region are rich in organic carbon, phosphorus and nitrogen and
finally finds its way into Palk Bay. The nutrient rich water (due to settling of unified feed
particle) discharges periodically from the shrimp farms however did not show influence
on nutrients content of sediment in estuary.
Sea Bed Characteristics
Geomorphology of the area exhibits tidal flats, estuaries and marsh zones as
well as linear stabilized older younger sand dunes. Beach dunes run parallel to the
sea.
Geologically, thick section of Quaternary alluvium overlies the Archean
charnockite rocks and these are in turn overlain by the Holocene tidal flat deposits.
The detailed lithological observation of cores reveals that the sediments have
been depositing in phases and that there has been pulsating supply of fine sediments
onto the tidal flats and estuaries. Sediment in the cores show very heterogeneous
mixture of quartz sand, biogenic carbonate and clay. Geomorphologic observations

reveal that the coarse sand in the tidal zones reflect ample sediment supply during the
Northeast monsoons. A number of different types of topographical features are found
in the study area, such as continental shelves, deep sea basins, troughs, trenches and
continental slopes.
Sediments are moderately well stored and slightly well skewed. Kurtosis
value of 0.3 shows less sorting in grain size distribution. Clay is absent and sediments
are made of detritus. Different grain size sediment show variable levels of heavy metal
(Fe, Mn, Cr, Cu, Pb, Zn, Cd & Hg) concentration (Table 1.1).
1.5 Environmental Impact Assessment (EIA)
The pre-construction phase would involve land acquisition, resettlement
and rehabilitation of affected population as also compensation hence impacts due to
such activities are required to be assessed.
During the construction phase there will be considerable increase in rail and
road traffic to and from the island for transportation of men, material, machinery and
equipment. Also, the land access, now available to the local fisher folks, to
Dhanushkody area for traditional fishing may be hindered unless alternative
arrangements are made. The potential sites for dredging and disposal of dredged
material are to be decided as also shipping operations will have to be regulated so as
to cause minimum disturbance to the normal fishing activities.
During the operation phase of the channel, the potential sources of marine
pollution are spillage of oil and grease, marine litter, jetsam and floatsam including
plastic bags, discarded articles of human use from the sea-borne vessels hence
impacts due to such wastes are to be assessed.
The channel may facilitate the movement of fishes and other biota from the
Bay of Bengal to the Indian Ocean and vice versa. By this way, the entry of oceanic
and alien species into the Palk Bay and the Gulf of Mannar, as also the disposal of
endemic species outside the Palk Bay and the Gulf of Mannar may occur.
The project is expected to provide employment opportunities and avenues of
additional income through establishment of small ancillary industries. The project will
also trigger development of coastal trade between the ports south and north of
Rameswaram, consequently reducing the load and congestion on railways and

roadways. The project will help in saving considerable foreign exchange through
reduction in oil import bill, and generate revenue income from dues levied on ships
transiting the canal which will add to the national economy.
1.5.1 Objectives of EIA Study
The objectives of the study is to carry out assessment of environmental impacts, its
quantification and for delineating environmental management plan for Sethusamudram Ship
Channel project to enable the Ministry of Shipping to obtain environmental clearances from
concerned local, state and central Government authorities. The environmental assessments
are to be carried out in keeping with the applicable guidelines and notifications of the
regulatory agencies as also the International transboundary concerns.
The rapid environmental impact assessment study report was prepared incorporating
primary data collected for the region and also available secondary data, environmental impact
statement based on identification, prediction and evaluation of impacts, ranking of
environmentally viable alternatives and environmental management plan for the acceptable
route. The comprehensive EIA report was prepared later based on the primary data collection
for region.The area for Environmental Impact Assessment Study is shown in Fig. 1.3.
1.5.2 Scope of the Study
The scope of the comprehensive EIA study is summarised as follows :
i. Assessment of the present status of coastal water, marine, land, biological and
socio-economic components of environment including parameters of human
interest along the proposed ship canal route
ii. Identification of potential impacts on various environmental components due
to activities envisaged during pre-construction, construction and post-
construction/ operational phases of the proposal
iii. Prediction of impacts on the various environmental components using
appropriate mathematical/simulation models
iv. Preparation of environmental impact statement based on the identification,
prediction and evaluation of impacts
v. Preparation of detailed Environmental Impact Statement (EIS) duly bringing
out the likely impacts of the project, mitigation, protection and enhancement

measures including impacts due to the disposal of dredged materials,
consideration of alternatives, etc.
vi. Short-listing of viable routes for the proposed shipping canal based on
technical requirements, and delineation of acceptable canal route for shipping
based on environmental considerations
vii. Delineation of Environmental Management Plan (EMP) outlining preventive
and control strategies for minimising adverse impacts for various stages of the
proposed project including the costs and time schedules for its implementation
viii. Formulation of environmental quality monitoring programme for various
phases of the project to be pursued as per the requirements of statutory
authorities
1.5.3 Plan of Work
• Collation/ collection of primary and secondary data on benthic flora/
fauna, meiobenthos, bacrobenthos
• Collation/collection of primary and secondary data on phytoplankton,
zooplankton in water column
• Assessment of general physico-chemical quality of water
• Assessment of sediment quality and its texture
• Fishery potential of the region
• Collation of secondary data on bathymetry, sediment transport, water
current and directions, wave height, tidal variation, dispersion
coefficients and other hydrographic parameters
• Collection of information about marine parks and ecologically sensitive
species
• Qualitative and quantitative assessment of waste loads likely to accrue
from proposed activities in the hinterland all along the canal
• Assessment of change in hydrographic pattern in the region during and
after implementation of dredging activities vis-à-vis impact on coastal
ecosystems

• Assessment of impacts on food chain productivity, growth of benthos
and vegetation, phytoplankton densities predatory fish and birds in the
coastal waters
• Assessment of impacts on ecological health due to hydrodynamic and
water quality changes
1.5.4 Components included in the Study
1.5.4.1 Coastal Water Environment
• Study of coastal water environment with respect to its physico-chemical
and biological characteristics
• Assessment of mangrove forests/vegetation in the coastal and inter-
tidal zones
• Determination of primary and secondary productivity in the coastal
region
• Prediction of impacts of discharges during dredging on marine water
quality
• Evaluation of impacts due to shipping activities in keeping with the CRZ
regulations
1.5.4.2 Marine Environment
• Establishing abiotic and biotic characteristics of water and sediment
component of marine environment

• Delineation of hydrodynamic conditions (tide, current, wind and waves)
including the pattern of movement of sea-bed material in the project
region
• Assessment of impacts of dredging, transportation and disposal of
dredged materials like interference with fishing, increased turbidity and
disturbance to the flora and fauna
• Identification of likely impacts on the islands/region along the shipping
canal
• Prediction of impacts of the project on other natural marine processes
1.5.4.3 Land Environment
• Study of existing landuse pattern, vegetation and forestry along the
coastline of the region
• Assessment of impacts on landuse pattern of main land and islands
with respect to agriculture and forestry due to proposed project
1.5.4.4 Biological Environment
• Identify the sensitive receptors and ecological systems within the study
region
• Collection of information about flora and fauna and determination of
species diversity, density, abundance etc.
• Collection of available information on both terrestrial and aquatic flora
and fauna, including rare and endangered species in the study region
• Assessment of potential impacts on aquatic flora and fauna due to
effluent discharges
• Prediction of stress on biological environment in the study region
• Estimation of anticipated impacts on fisheries and other useful aquatic
flora and fauna
• Delineation of measures for abatement/reduction of biological stress
1.5.4.5 Socio-economic and Health Environment

Collection of baseline data related to socio-economic profile of the study region
with reference to :
• Human settlements, occupational pattern, employment and income in
the region
• Infrastructure resource base, viz. Medical, education, water resources,
power supply
• Economic resource base, viz. Agriculture, industries, forest, trade and
commerce
• Health status, viz. morbidity pattern with reference to prominent and
endemic diseases
• Cultural and aesthetic attributes in the study region including places of
historical/ archeological, religious, recreational importance
- Estimation of disruption in social life due to relocation of human
settlements and assessment of rehabilitation requirement
- Assessment of impacts on places of historical/ archeological importance
and aesthetic impairment
- Assessment of economic benefits to community and environment due to
the proposed activities
1.5.4.6 Ecological Risks
• Quantification of ecological risks and delineation of ecological risk
mitigation measures
• Study and survey of environmentally sensitive sites viz. spawning and
breeding grounds and coral reefs
• Analysis of information with regard to environmental impact (direct,
synergistic and cumulative) and associated nagivational and landward
activities in and around the project region
• Quantification of ecological risks with recourse to appropriate
ecosystem models
1.5.5 Environmental Management Plan

Environmental Management Plan (EMP) is to be drawn for the pre-
construction, construction and operational phases after identifying, predicting and
evaluating the impacts on each component of the environment with a view to
maximising the benefits from the proposed project. The EMP to be prepared would
mainly cover mitigation measures at dredging sites, transportation route (of dredged
spoil), and dumping site. EMP would essentially consist of details of work proposed
under mitigation measures, implementation schedule of such measures, fund and
manpower requirements.
1.6 Techno-economic Viability
1.6.1 Traffic Potential
The future traffic potential is to be studied over short, medium and long term
time horizons in terms of volumes of cargoes in tonnage like container, dry, liquid,
bulk, also number, size and category of ships and other types of vessels taking into
due consideration the future economic growth.
1.6.2 Alignment of Channel
Alignment of the channel is to identified with reference to environmental
factors, navigational aspects, morphological aspects, seabed movements/
sedimentation likely to be induced by the cross currents in the canal after its creation
and during operation.

1.6.3 Dredging and Disposal Areas
The disposal areas (within Indian territory) of the dredged materials are to be
spelt out to satisfy the statutory requirements of State/ Central Govt. Deptts./Ministry of
Environment & Forests and other concerned Archeological Deptt., Tamilnadu Pollution
Control Board, Tamilnadu Maritime Board etc. so as to ensure that the dumping of
dredged materials will not adversely affect the environment. Study the transboundary
effects such as flooding and effects of fishery potential etc. on the Sri Lankan side due
to the disposal of dredged materials. Also, the quantum of maintenance dredging per
annum, its periodicity, disposal areas etc. are to be assessed.
1.6.4 Cost Estimates and Economic Viability
This would include the project cost estimates towards preliminary surveys and site
investigations; dredging costs, transportation and dumping of dredged material at the chosen
sea/land locations. The economic analysis for a selected route will also be carried out.
1.7 Permits and Approvals
Permits and approvals from the following mentioned agencies / organisations
are envisaged :
• Tamilnadu State Pollution Control Board
• Tamilnadu State Forest & Environment Department
• Tamilnadu Maritime Board
• State Wildlife Warden
• Chief Conservator of Forests
• Ministry of Environment & Forests
• Ministry of Defence / Indian Navy
• Archeological Department
• Ministry of External Affairs
• Sri Lankan Government

Fig. 1.2 : The Gulf of Mannar and Palk Bay/Palk Strait Area

Fig. 1.3 : The Study Area

Table 1.1
Texture, Mineralogy and Elemental Composition of Sediments in Palk Strait
Statistical Parameters of Sediments (units in φ)
Area Mean Dispersion Skewness Kurtosis Median
Palk strait 2.4 0.4 -0.07 0.3 2.3
Percentage of Various Minerals in Sediments
Area Quartz Feldspar Carbonates Clays
Palk strait 64 4 32 --
Chemical Composition of Bed Sediments
Fe Mn Cu Pb Zn Cd Hg
Area Cr ppm Org carb
% ppm ppm ppm ppm ppm ppb %
Palk strait / 0.38 110 122 8 8-40 34 1-2 107 0.09
Palk Bay
Gulf of Mannar 0.35 90 BDL-10 BDL-70 10 BDL-40 BDL BDL 0.3-0.4

2. Proposed Project and
Oceanographic
Environmental Setting
2.1 Proposed Project
The project envisages a ship navigation channel across Adam’s bridge
connecting Gulf of Mannar with Palk Bay and further Palk Bay with Bay of Bengal with
dredging of navigational channel in Palk strait. The project enables the direct
movement of ship between the east & west coast of the country instead of going via
Srilanka. The route will originate from Tuticorin harbor, extend N-E up to south of
Pamban island using available navigation depths which is more than 20 m, cut through
Adam’s Bridge where a channel will be required to be dredged with depth suiting the
draft requirement and proceed parallel to medial line for fishing rights in Palk Bay
through available navigation depth, pass through a channel to be created in Palk strait
by dredging and join Bay of Bengal. The construction of ship channel will be done to
suit different drafts 9.15m, 10.7m & 12.8m by dredging & Excavation in Adam’s Bridge
area and Palk strait.
• Tentative specification of Navigational channel are :
− First phase : 9.15-m draft. 300m width
− Second phase : 10.7 m draft 300m width
− Third phase : 12.8 m draft 500 m width
• Phase wise development
− First phase : control two way traffic
− Second phase : control two way traffic
− Third phase : two way traffic
The project besides creating a channel envisages deployment of Vessel
Traffic Management System (VTMS) to be located on Rameshwaram Island and at pt.
Calimere to control navigation. Provision will be made for necessary navigational aids
which include lighted Fairway Buoys, channel marked, Buoys, Recons, flotilla etc.

NEERI has undertaken studies for assessing environmental status of the region and
have engaged services of National Ship Design Research Center (NSDRC),
Visakhapattanam for oceanographic & hydrographic surveys besides drilling
operations along proposed alignment, to collect borehole data. Services of National
Hydrographic Office (NHO) Dehradun were engaged to conduct bathymetry and
bottom profile studies in Palk Bay Strait area.
2.2 Oceanographic Status in Project area along Route
Alignment
The stability of the study area along the alignment is influenced by number of
environmental factors, primarily due to geological, biological, meteorological and
oceanographical parameters, which distinctly vary from one sector of the coast to
another. The most influencing factors in coastal waters are the tides, waves and
currents, and they interact each other to produce an energy input, which shapes and
modifies the shore. Any attempt to study these problems require a thorough
understanding of the factors and processes involved in the coastal geomorphological
system, the pattern of sediment transport in the littoral zone, the volume of exchange
of littoral drift from one region to another, the monthly and seasonal variation, and the
intermittent oceanographic factors acting on the system.
2.2.1 Waves
The winds blowing over the ocean surface has the direct effect on wave
generation as it is related to wind speed, extent of fetch and wind duration. Pilot (1953)
gives a detailed account of the southern part of the Bay of Bengal. The oceanographic
pattern along the Indian coast is mainly governed by the monsoons. The southwest
monsoon influences this pattern from June to September. The average speed of the
wind during southwest monsoon period is about 35 km per hour frequently rising up to
45-55 km per hour. The average speed of the wind during northeast monsoon
(October to January) prevails around
20 km per hour. Tropical storms known as cyclones frequently occur in the Bay of
Bengal during October to January.
In eastern coast, the wave activity is significant both during southwest and
northeast monsoons.

2.2.1.1 Wave Measurement
The observations on wave measurement show that significant wave height
varied from 0.46 to 1.12 m in March, 0.33 to 1.18 m in April, 0.46 to 1.74 m in May,
0.71 to 1.78 m in June, 0.68 to 1.6 m in July, 0.68 to 1.49 in August, 0.64 to 1.76 m in
September, 0.54 to 1.35 m in October, 0.40 to 1.13 m in November, 0.40 to 1.12 m in
December, 0.35 to 1.03 m in January and 0.35 to 1.23 m in February. Measured
significant wave height is given in Fig. 2.1
The maximum wave height varied from 0.67 to 1.78 m in March, 0.44 to 1.73
m in April, 0.66 to 2.81 m in May, 0.98 to 2.72 m in June, 0.91 to 2.45 m in July, 0.89
to 2.48 in August, 0.89 to 2.96 m in September, 0.66 to 2.94 m in October, 0.59 to
1.60m in November, 0.48 to 1.73 m in December, 0.47 to 1.68 m in January and 0.45
to 1.79 m in Febraury. Wave heights are relatively higher during southwest monsoon.
Measured maximum wave height is depicted in Fig. 2.2.
Monthly variation of breaking wave height (m) is depicted in Table. 2.1
The wave direction (with respect to north) mostly prevailed 140O to 230O in
southwest monsoon (June to September), 85O to 150O during northeast monsoon
(October to January), and 90O – 200O during fair weather period (February to May).
The wave direction is highly variable in January and May. The zero crossing wave
period predominantly varied 3-8 s in December to April, 4-10 s in May and 4-9 s during
rest of the year.
The wave heights recorded in west and east coast offshore area of India are
compared. In west coast the wave heights off Mumbai are in between 2.0-6.0 m in
southwest monsoon, 2.0-3.0 in north east monsoon, and 1.0-2.5 m in fair weather
period. Off Goa the wave heights are between 0.8-5.1 m in southwest monsoon. Off
Mangalore wave heights are around 3.2 m in southwest monsoon and 0.8 m in fair
weather period. Off Trivandrum the wave heights are 2-4.3 m in southwest monsoon
and 1-2.0 m in fair weather period. Off Cochin the wave heights are between 0.9-2.0 in
southwest monsoon. In east coast off Chennai the wave heights are 2.5 m in
southwest monsoon and 1 m in northeast monsoon. Off Visakhapatnam coast these
heights are between 0.8-3.9 m in southwest monsoon 0.6-2.9 m in northeast monsoon
and 0.5-3.8 m in fair weather period. Off Orissa the wave heights are between 1.0-2.5

m in southwest monsoon and 0.8-2.5 m in northeast monsoon, and around 1-2.2 m in
fair weather period.
The wave climate reported in the literature indicates that the wave activity in
the study region remains relatively low compared to the rest of Indian coast.
2.2.1.2 Wave Refraction
Tuticorin to Arimunai
Wave refraction during the southwest monsoon shows appreciable
divergence of wave orthogonal near Adams Bridge, Arimunai, and south of
Sippikulam. Wave activity was found to be extremely reduced between Mandapam
and north of Valinokkam due to the presence of offshore islands, which causes waves
to break offshore. Wave energy concentration was observed at Mukkuperiyar,
Valinokkam, Mukkaiyur and Vember. The region between Sippikulam and Tuticorin is
again protected from southwestern waves due to the presence of islands. The
presence of offshore islands is observed to protect the coastal stretch from Mandapam
to Valinokkam, and Veppalodai to Tuticorin from northeasterly waves. Wave refraction
between Tuticorin and Arimunai during NE Monsoon and SW Monsoon is shown in
Figs. 2.3-2.5 respectively.
Arimunai to Vedarnyam
This segment of the coastline lies in Palk Bay and waves propagating from
south (during southwest monsoon and fair weather period) do not enter in this region.
Studies are indicating that even during the northeast monsoon, waves are found not
entering the bay and get attenuated across the shoals of middle banks and south
banks between Vedaranyam (India) and Matakal (Sri Lanka). Part of wave energy with
less magnitude enters the bay through Pedro Channel and reach the coast between
Puduvalasai and Gopalpatnam. Wave refraction between Arimunai and Vedaranyam
during NE Monsoon is shown in Fig. 2.6 respectively.

2.2.1.3 Wave Period
During southwest monsoon, the wave period predominantly persisted 9 –10 s
between Vembar and Keelamunadal, and 6 – 8 s between Uthalai and Dhanushkodi.
During the northeast monsoon, it predominantly persisted 5 –10 s between Vembar
and Keelamundal, and 5 –8 s between Uthalai and Dhanushkodi east. In fair weather
period, it remained 6 –10 s along Vembar to Keelamundal, and 9 –10 s along Uthalai
to Dhanushkodi. The study shows that the waves approaching the coastline consist of
both seas and swells.
Monthly variation of wave period is depicted in Table 2.2. Predominent wave
character buoy data off Vembar from wave rider is given in Table 2.3.
2.2.2 Tides and Currents
The tides in this region are semidiurnal. The various important tide heights
with respect to chart datum near Pamban pass are as follows.
Mean Higher High Water Springs = 0.70 m
Mean High Water Neaps = 0.48 m
Mean Sea Level = 0.41 m
Mean Low Water Neaps = 0.32 m
Mean Low Water Springs = 0.06 m
It shows that the average spring tidal range is about 0.64 m and the neap tidal
range is about 0.16 m. The tidal range is relatively low compared to the northern part
of the Indian coast, which inturn would restrict the influence of tidal currents.
2.2.2.1 Longshore Currents
The longshore current speed remained weak (<0.1 m/s) throughout the year
between Keelamundal and Vedalai and along the northern coast of Rameswaram
from Arimunai to Ariyaman. Consequently, it was relatively moderate (>0.1 m/s)
throughout the year between Sippikulam and Naripaiyur and along the southern coast
of Rameswaram i.e. from Uthalai to Mukkuperiyar.
The spit between Dhanuskodi and Arimunai in Gulf of Mannar experienced
relatively stronger currents during fair weather period (March to May) and remained
weak during southwest monsoon and northeast monsoon periods (June to February).
It indicates that the stronger currents prevailing in the adjacent coasts during

southwest/northeast monsoons becoming weaker between Dhanushkodi and
Arimunai. This phenomenon of sudden weakening of littoral currents causes the littoral
drift to deposit and form series of sand shoals near Arimunai. Such prolonged
deposition of littoral drift over many years can be attributed to formation of numerous
islands and shallow shoals across the strait between Arimunai (India) and
Talaimannar (Sri Lanka) called Adam’s Bridge.
The Uthalai coast facing Gulf of Mannar experienced stronger longshore
currents (0.2 – 0.5 m/s) throughout the year, followed by a segment of the coast
between Vembar and Naripayur (0.2 – 0.4 m/s) with exposure to relatively high wave
energy environment.
The prevalence of weak longshore currents between Keelamundal and
Vedalai is causing deposition of littoral drift on either side, as evidenced by the
occurrence of many offshore islands and submerged shoals.
Although the Pamban Pass, connecting Palk Bay and Gulf of Mannar break
the continuity of longshore current between the mainland and Rameswaram Island,
the magnitude of the current on either side of Pamban Pass is found to be very weak.
This reduces the volume of littoral sediments approaching the Pamban Pass which
inturn reduces the quantity of sediment passing through Pamban Pass from Gulf of
Mannar to Palk Bay.
The longshore current direction prevailed northerly during southwest
monsoon and fair weather period, and southerly during northeast monsoon between
Sippikulam and Uthallai. The entire coast of Rameswaram facing Gulf of Mannar,
experienced the current in westerly direction throughout the year, except in June and
July. This phenomenon of northerly currents along the mainland and westerly current
along Rameswaram create a zone, wherein, most of the littoral drift will get deposited.
Only a fractional proportion is expected to move from this region by tide induced
currents towards the Adams Bridge. This would reduce the volume of littoral sediment
reaching the Adam’s Bridge and intrun. The quantity of sediment entering Palk Bay
from Gulf of Mannar. These sediments deposited at
shoals is supplied back to the littoral system for the mainland, when the longshore
currents move towards south during the ensuing northeast monsoon.

Although the longshore current was extremely weak along the sand spit
facing Palk Bay, it tends to be easterly during southwest monsoon/fair weather period
and westerly during northeast monsoon. Similarly, at Ariyaman, the longshore current
direction was southerly during southwest monsoon/fair weather period and northerly
during northeast monsoon, indicating just opposite to the phenomenon observed in
Gulf of Mannar. Such processes once again indicate the accumulation of littoral drift
on either side of Rameswaram Island during southwest monsoon and removal during
northeast monsoon, making this region as a sediment storage reservoir.
Monthly variation of longshore current (m/s) is given in Table 2.4.
2.2.2.2 Currents Studies
Continuous measurements on tidal current speed and direction were carried
out for three seasons at 4 locations viz., i) stn. C1 - off Arimunai-Adam’s Bridge, ii) stn.
C2 - off Uthalai (Gulf of Mannar), iii) stn. C3 - Pamban Pass, and iv) stn. C4 - off
Tharuvai (Palk Bay). The measured currents were resolved into parallel and
perpendicular components with respect to the coastline. The variation of current speed
and direction and the resolved components are presented in Figs. 2.7 to 2.35.
Southwest monsoon (June to September)
Near Arimunai (stn. C1) the average current speed occurred around 0.2 m/s
with the maximum and minimum speed of 0.3 m/s and 0.05 m/s respectively both at
surface and bottom (Fig. 2.7). The variation of current direction had not followed the
tidal phase. It showed consistent northwesterly flow over one tidal cycle and changed
to southeasterly flow for the subsequent tidal cycle. It indicates that current shifted its
flow direction for alternate tidal cycles rather than flood and ebb tidal phases. The
shore parallel component of currents indicates that for larger tidal range, the flow was
in westerly direction and for small range in easterly direction. The shore perpendicular
component of currents indicates that the flow consistently existed from Gulf of Mannar
into Palk Bay. The northwesterly and southeasterly currents over different tidal cycles
were found to be equally predominant.The component of currents near surface and
bottom off Ariminai during southwest monsoon is depicted in Fig. 2.8 and Fig. 2.9
respectively.
At Uthalai (stn. C2) in Gulf of Mannar, the average current prevailed around
0.1 m/s with the maximum and minimum of 0.2 m/s and 0.05 m/s respectively (Fig.

2.10). Similar to stn. C1, the bottom current was seen responding to tides flowing east
over one tidal cycle and west during the subsequent tidal cycle. The direction of flow
was predominant in southeasterly direction for larger tidal range and northwesterly
direction for small tidal range. The shore parallel component of currents indicates that
the flow shifted in southeast and northwest both at surface and bottom. The shore
perpendicular component of currents indicates that the flow shifts towards northeast
and southwest both at surface and remains consistently northeast at bottom. The
component of currents near surface and bottom off Rameswaram during southwest
monsoon is depicted in Fig. 2.11 and Fig. 2.12 respectively.
The variation of currents at surface measured near Pamban Pass (stn. C3) is
shown in Fig. 2.13. The current speed was found to be strong showing an average of
0.5 m/s, with the maximum of 1 m/s and minimum of 0.1 m/s. Current direction
remained consistently northeast flowing from Gulf of Mannar into Palk Bay. Variation
of current speed shows that the magnitude of the current speed was more during flood
and less during ebb tide indicating the influence of tides over the seasonal
unidirectional flow. The shore parallel component of currents indicates that the flow is
into Palk Bay with high speed during flood tide and low speed during ebb tide. The
shore perpendicular component of currents indicates that the flow is across the
Pamban Pass towards Rameswaram Island. The component of currents near surface
off Pamban Pass during southwest monsoon is depicted in Fig. 2.14.
At Tharuvai (stn. C4), the average current speed of 0.2 m/s with the maximum
of 0.3 m/s and minimum of 0.1 m/s were observed both at surface and bottom (Fig.
2.15). The flow was unidirectional towards southeast but the current speed varied with
tidal phase. Current speed was high during flood tide and low during ebb tide
indicating the strong influence of seasonal circulation current towards northeast during
southwest monsoon period. The shore parallel component of currents indicates that
the flow was towards southeast at surface and bottom. The shore perpendicular
component of currents indicates the flow was towards northeast both at surface and
bottom. The component of currents near bottom off Tharuvai during southwest
monsoon is depicted in Fig. 2.16.
The measurement shows that during southwest monsoon when the tidal
range is large, the opposite direction of flow prevail between Adam’s Bridge (stn. C1)
and Uthalai (stn. C2) would cause the water mass to flow from Gulf of Mannar to Palk

Bay. This flow would transport sediments into Palk Bay from Gulf of Mannar. On the
other hand, when the range is small, the divergence of flow occurring near Adams’s
Bridge (stn. C1) and Uthalai (stn. C2) would initiate a flow from Palk Bay into Gulf of
Mannar through Adam’s Bridge. Thus the sediment exchange taken place into Palk
Bay during large tidal range day would return back to Gulf of Mannar.
Northeast Monsoon (October to January)
Near Arimunai (stn. C1), current was generally weak showing an average of
0.1 m/s, with the maximum of 0.2 m/s and minimum of 0.05 m/s (Fig. 2.17). The flow
direction remained unidirectional towards west both at surface and bottom. The
current speed increased during flood tide and reduced during ebb tide. The shore
parallel component of currents indicates that the flow was consistently towards
northwest at surface and bottom. The shore perpendicular component of currents
indicates the flow prevailed northeast at surface and southwest at bottom. The
component of currents near surface and bottom off Arimunai during northeast
monsoon is depicted in Fig. 2.18 and Fig. 2.19 respectively.
The variation of currents at Uthalai (stn. C2), showed an average current
speed of 0.08 m/s, with the maximum of 0.15 m/s and a minimum of 0.04 m/s (Fig.
2.20). The bottom flow was nearly unidirectional towards southeast. The shore parallel
component of currents indicates that the flow was oscillating in southeast and
northwest at surface and remaining consistently southeast at bottom. The shore
perpendicular component of currents indicates that the flow was towards northeast
both at surface and bottom. The component of currents
near surface and bottom off Rameswaram during northeast monsoon is depicted in
Fig. 2.21 and Fig. 2.22 respectively.
The currents at Pamban Pass (stn. C3) prevailed strong with the average of 1
m/s, maximum of 1.4 m/s and minimum of 0.5 m/s (Fig. 2.23). Currents remained
consistently unidirectional around 2250. The change in tidal phase caused the variation
in current speed showing stronger currents during ebb tide and reduction in current
speed during flood tide. It indicates that the flood tide propagates from Gulf of Mannar
to Palk Bay and vice versa. The shore parallel component indicates that the flow was
consistently from Palk Bay into Gulf of Mannar during ebb tide and flood tide. The
shore perpendicular component of currents indicates the flow was across the Pamban

Pass from Rameswaram to Mandapam. The component of currents near surface off
Pamban Pass during northeast monsoon is depicted in Fig. 2.24 respectively.
The current was found to be weak off Tharuvai at Palk Bay (stn. C4) showing
the average speed of 0.1 m/s, maximum of 0.13 m/s and minimum of 0.04 m/s (Fig.
2.25). Similar to stn. C3, the current flow was unidirectional towards 250O, but the
speed was high during ebb tide and low during flood tide. The shore parallel
component of currents indicates that the flow was towards northwest both at surface
and bottom. The shore perpendicular component of currents indicates that the flow
was towards southwest both at surface and bottom. The component of currents near
surface and bottom off Tharivai during northeast monsoon is depicted in Fig. 2.26 and
Fig. 2.27 respectively.
The observation during northeast monsoon indicates that the current flow was
more influenced by seasonal flow than by tides. Stronger currents were observed
during ebb tides flowing from Palk Bay into Gulf of Mannar through Pamban Pass. The
currents were generally weak in Gulf of Mannar and Palk Bay (stns. C2 and C4).
Significant flow from Palk Bay to Gulf of Mannar was observed through Adam’s Bridge
also. Such current pattern during northeast monsoon can transport and exchange the
sediments from Palk Bay into Gulf of Mannar.
Fair weather (February to May)
The variation of currents near Arimunai (stn. C1) at surface and bottom are
shown in Fig. 2.28. The current was generally weak showing average of
0.1 m/s, with the maximum of 0.2 m/s and minimum of 0.05 m/s. The current flow was
found to be unidirectional towards northwest both at surface and bottom. The shore
parallel component of currents indicates that the flow was towards northwest both at
surface and at bottom. The shore perpendicular component of currents indicates the
flow was changed its direction in northeast and southwest both at surface and bottom.
The component of currents near surface and bottom off Arimunai during fair weather is
depicted in Fig. 2.29 and Fig. 2.30 respectively.
At Gulf of Mannar (stn. C2), the current was weak with average of 0.1 m/s,
maximum of 0.2 m/s and minimum of 0.04 m/s (Fig. 2.31). The flow remained
unidirectional consistently towards 305O, but the current speed varied randomly
between 0.04 and 0.12 m/s. The shore parallel component of currents indicates that
the flow was towards northwest both at surface and bottom. The shore perpendicular

component of currents indicates the flow changed the direction from northeast to
southwest both at surface bottom. The component of currents near surface and
bottom off Rameswaram during fair weather is depicted in Fig. 2.32 and Fig. 2.33
respectively.
The flow through the Pamban Pass (stn. C3) was quite distinct, showing the
average speed of 0.3 m/s, maximum of 0.6 m/s and minimum of 0.04 m/s. The varition
of currents off Pamban Pass at surface and bottom are shown in Fig. 2.34.Current
flow was noticed towards 45°, i.e., into Palk Bay during flood tide and towards 225°,
i.e., into Gulf of Mannar during ebb tide. The shore parallel component of currents
indicates that the flow was into Palk Bay during flood tide and into Gulf of Mannar
during ebb tide. The shore perpendicular component of currents indicates the flow was
changing its direction across the Pamban Pass between Mandapam and
Rameswaram. The component of currents near surface off Pamban Pass during
southwest monsoon is depicted in Fig. 2.35.
During fair weather period, the change in current direction was observed over
the tidal phases at Pamban Pass. The study shows that the current flows mostly
parallel to the coast. The general circulation of current in northwesterly direction
dominates the tide induced current. This would help the sediments to move by tide
induced currents from Gulf of Mannar to Palk Bay prevailing through Pamban Pass
and to some extent through Adam’s Bridge.

2.2.3 Sediment Transport
In Indian coast, various investigations pertaining to different fields of
oceanography were carried out by a number of research workers. Sediment transport
along the east coast of India was initiated by Lafond and Prasada Rao (1954) and
subsequently by many other investigators.
The formation of sand islands off Tuticorin region indicates this region acts as
a sediment sink with progressive accumulation of sand. The large beach storage of
sand between Manppad and Tiruchendur, Vembar and Valinokkam and Rameswaram
Island indicates the depositional features of littoral sediments.
The geographical formation of Tamilnadu coast plays a vital role maintaining
the stability of the Indian shoreline. It determines the extent of sources and sinks for
the littoral drift moving around the Indian peninsular tip across the east and west
coasts of India. Based on the characteristics of the sediment processes and the
various influencing parameters, the Tamilnadu coastline can be classified into 6
segments viz., i) open coast in Bay of Bengal – Pulicat to Pondicherry, ii) partly
protected coast in Bay of Bengal – Pondicherry to Vedaraniyam, iii) protected coast in
Palk Bay – Vedaraniyam to Dhanushkodi, iv) protected coast in Gulf of Mannar –
Dhanushkodi to Tuticorin, v) partly protected coast in Indian Ocean – Tuticorin to Ovari
and vi) open coast in Indian Ocean – Ovari to Thengaipattinam. The typical formation
of Tamilnadu coast comprises of long sandy beaches on the northern part. The stretch
between Pondicherry and Vedaraniyam has been experiencing a recession of
coastline since historical period. The coastlines between Vedaraniyam and
Rameswaram in Palk Bay and between Rameswaram and Tuticorin in Gulf of Mannar
are substantially protected from monsoon waves due to the proximity of Srilanka
Island. Palk Bay is very shallow and is largely occupied by sandbanks and submerged
shoals.
Rameswaram Island, the geological formation of coral atoll with huge sand
cover between India and Srilanka plays a vital role on the processes of exchange of
littoral drift between east coast and west coast. It separates the sea in the north by
Palk Bay and south by Gulf of Mannar. The wave sheltering effect due to Sri Lanka
Island, the large siltation in Palk Bay, the presence of numerous offshore islands in
Gulf of Mannar, the growing sand spit along Dhanushkodi and the shallow reef

(Adam’s Bridge) between Arimunai (India) and Thalaimannar (Sri Lanka) largely
modify the sediment movement. It is strongly evident that the coastal processes taking
place around the Rameswaram Island and the exchange of the littoral drift between
Gulf of Mannar and Palk Bay significantly determine the supply of sediments to the
rest of the east coast and in turn the stability of the region.
2.2.3.1 Longshore Sediment Transport
The longshore sediment rate varies with season for different location in the
study area. The detais of observation stations is given below and their longshore
sediment transport rate is given in Table 2.5 and shown in Fig. 2.36 to Fig. 2.40.
Sippikulam
The longshore sediment transport rate varied between 0.06-0.84 x 103
m3/month in southwest monsoon (June to September), between 0.05-2.14 x 103
m3/month in northeast monsoon (October to January) and between 0.03-0.09 x 103
m3/month in fair weather period (February to May). The annual gross transport rate
was 5.0 x 103 m3/year. The annual net transport was 1.4 x 103 m3/year towards south.
Vember
The longshore sediment transport rate varied between 0.35-3.84 x 103
m3/month in southwest monsoon (June to September), between 0.53-20.28 x 103 m3/
month in northeast monsoon (October to January) and 0.02-1.9 x 103 m3/month in fair
weather period (February to May). The annual gross transport rate was 34.0 x 103
m3/year. The annual net transport rate was 9.6 x 103 m3/year towards south.
Kannirajapuram
The longshore sediment transport rate varied between 3.7-23.94 x 103
m3/month in southwest monsoon (June to September), between 1.98-23.37 x 103
m3/month in northeast monsoon (October to January) and between 0.02-2.21 x 103
m3/month in fair weather period (February to May). The annual gross transport rate
was 97 x 103 m3/year. The annual net transport rate was 25.6 x 103 m3/year towards
north.
Naripaiyur
The longshore sediment transport rate varied between 2.3-29.29 x 103
m3/month in southwest monsoon (June to September), between 0.06-14.46 x 103
m3/month in northeast monsoon (October to January) and between 0.02-2.47 x 103

m3/month in fair weather period (February to May). The annual gross transport rate
was 66 x 103 m3/year. The annual net transport rate was 22.6 x 10 3 m3/year towards
south.
Keelamundal
The longshore sediment transport rate varied between 0.01-0.9 x 103
m3/month in southwest monsoon (June to September), between 0.55-17.46 x 103
m3/month in northeast monsoon (October to January) and between 0.14-5.73 x 103
m3/month in fair weather period (February to May). The annual gross transport rate
was 36 x 103 m3/year. The annual net transport rate was 3.1 x 103 m3/year towards
south.
Valinokkam
The longshore sediment transport rate varied between 0.01-0.06 x 103
m3/month in southwest monsoon (June to September), between 0.01-1.06 x 103
m3/month in northeast monsoon (October to January) and between 0.01-1.76 x 103
m3/month in fair weather period (February to May). The annual gross transport rate
was 3.0 x 103 m3/year. The annual net transport rate was 3.0 x 103 m3/year towards
north.
Kalimangundu
The longshore sediment transport rate varied between 0.01-0.68 x 103
m3/month in southwest monsoon (June to September), between 0.01-0.03 x 103
m3/month in northeast monsoon (October to January) and between 0.01-0.11 x 103
m3/month in fair weather period (February to May). The annual gross transport rate
was 1 x 103 m3/year. The annual net transport rate was 0.5 x 103 m3/year towards
north.
Vedalai
The longshore sediment transport rate varied between 0.02-0.88 x 103
m3/month in southwest monsoon (June to September), between 0.01 x 103 m3/month
in northeast monsoon (October to January) and between 0.01-0.05 x 103 m3/month in
fair weather period (February to May). The annual gross transport rate was 1 x 103
m3/year. The annual net transport rate was 1 x 103 m3/year towards north.
Kondugal

The longshore sediment transport rate varied between 0.88-14.96x103
m3/month in southwest monsoon (June to September), between 0.12-1.22 x 103
m3/month in northeast monsoon (October to January) and between 0.02-1.85 x 103
m3/month in fair weather period (February to May). The annual gross transport rate
was 25 x 103 m3/year. The annual net transport rate was 10.2 x 103 m3/year towards
north.
Uthalai West
The longshore sediment transport rate varied between 6.88-48.7 x 103
m3/month in southwest monsoon (June to September), between 0.25-4.61 x 103
m3/month in northeast monsoon (October to January) and between 2.28-27.0 x 103
m3/month in fair weather period (February to May). The annual gross transport rate
was 140x103 m3/year. The annual net transport rate was 72.6 x 103 m3/year towards
north.
Uthalai East
The longshore sediment transport rate varied between 9.12-44.97 x 103
m3/month in southwest monsoon (June to September), between 0.18-19.64 x 103
m3/month in northeast monsoon (October to January) and between
3 3
1.76-24.84 x 10 m /month in fair weather period (February to May). The annual gross
transport rate was 190x103 m3/year. The annual net transport rate was 48.9x103
m3/year towards north.
Mukkuperiyar West
The longshore sediment transport rate varied between 5.16-44.96x103
m3/month in southwest monsoon (June to September), between 0.26-6.02 x 103
m3/month in northeast monsoon (October to January) and between 2.64-20.83 x 103
m3/month in fair weather period (February to May). The annual gross transport rate
was 120x103 m3/year. The annual net transport rate was 5.6 x 103 m3/year towards
north.
Mukkuperiyar East
The longshore sediment transport rate varied between 1.78-28.65x103
m3/month in southwest monsoon (June to September), between 0.02-17.98 x 103
m3/month in northeast monsoon (October to January) and between 1.98-20.10 x 103

m3/month in fair weather period (February to May). The annual gross transport rate
was 110x 103 m3/year. The annual net transport rate was 79 x 10 3
m3/year towards
north.
Dhanushkodi West
The longshore sediment transport rate varied between 2.31-17.05x103
m3/month in southwest monsoon (June to September), between 0.04-5.16 x 103
m3/month in northeast monsoon (October to January) and between 1.32-28.35 x 103
m3/month in fair weather period (February to May). The annual gross transport rate
was 83 x 103 m3/year. The annual net transport rate was 22.1 x 103 m3/year towards
north.
Dhanushkodi Mid
The longshore sediment transport rate varied between 1.76-14.0 x 103
m3/month in southwest monsoon (June to September), between 0.02-0.90 x 103
m3/month in northeast monsoon (October to January) and between 8.59-29.35 x 103
m3/month in fair weather period (February to May). The annual gross transport rate
was 96.0x103 m3/year. The annual net transport rate was 32.0 x 103 m3/year towards
north.

Dhanushkodi East
The longshore sediment transport rate varied between 1.20-19.28x103
m3/month in southwest monsoon (June to September), between 0.06-13.75 x 103
m3/month in northeast monsoon (October to January) and between 2.43-31.73 x 103
m3/month in fair weather period (February to May). The annual gross transport rate
was 125x103 m3/year. The annual net transport rate was 80.0x10 3
m3/year towards
north.
Arimunai West
The longshore sediment transport rate varied between 1.05-27.77x103
m3/month in southwest monsoon (June to September), between 0.07-0.44 x 103
m3/month in northeast monsoon (October to January) and between 1.06-8.99 x 103
m3/month in fair weather period (February to May). The annual gross transport rate
was 65.0x103 m3/year. The annual net transport rate was 43.7x103 m3/year towards
north.
Arimunai East
The longshore sediment transport rate varied between 0.90-35.97x103
m3/month in southwest monsoon (June to September), between 0.01-2.18 x 103
m3/month in northeast monsoon (October to January) and between 0.53-8.99 x 103
m3/month in fair weather period (February to May). The annual gross transport rate
was 73.0x103 m3/year. The annual net transport rate was 36.4x10 3
m3/year towards
north.
Mukkuperiyar West (Palk Bay)
The longshore sediment transport rate varied between 0.02-0.12x103
m3/month in southwest monsoon (June to September), between 0.02-1.90 x 103
m3/month in northeast monsoon (October to January) and between 0.02-0.34 x 103
m3/month in fair weather period (February to May). The annual gross transport rate
was 3.0x103 m3/year. The annual net transport rate was 2.7x103 m3/year towards
north.

Uthalai West (Palk Bay)
The longshore sediment transport rate varied between 0.02-0.11x103
m3/month in southwest monsoon (June to September), between 0.02-1.70 x 103
m3/month in northeast monsoon (October to January) and between 0.02-2.65 x 103
m3/month in fair weather period (February to May). The annual gross transport rate
was 5.0 x 103 m3/year. The annual net transport rate was 4.6 x 103 m3/year towards
north.
Villuvandithirtham
The longshore sediment transport rate varied between 0.01-0.03x103
m3/month in southwest monsoon (June to September), between 0.02-1.47 x 103
m3/month in northeast monsoon (October to January) and between 0.01-0.05 x 103
m3/month in fair weather period (February to May). The annual gross transport rate
was 2.0x 103 m3/year. The annual net transport rate was 1.6x10 3
m3/year towards
north.
Light House
The longshore sediment transport rate was 0.01 x 103 m3/month in southwest
monsoon (June to September), between 0.01-0.02 x 103 m3/month in northeast
monsoon (October to January) and between 0.01-0.07 x 103 m3/month in fair weather
period (February to May). The annual gross transport rate was 1.0 x 103 m3/year. The
annual net transport rate was 0.1 X 103 m3/year towards north.
Ariyaman
The longshore sediment transport rate varied between 0.01-0.06x103
m3/month in southwest monsoon (June to September), between 0.02-5.29 x 103
m3/month in northeast monsoon (October to January) and between 0.01-0.07 x 103
m3/month in fair weather period (February to May). The annual gross transport rate
was 23.0x103 m3/year. The annual net transport rate was 23.0x10 3
m3/year towards
north.
During southwest monsoon, the longshore sediment transport was
considerable (>10 X 103 m3/month) along the spit facing Gulf of Mannar and negligible
on Palk Bay side. Very close to the tip i.e., near Arimunai, the longshore transport
direction dominated in easterly direction indicating the movement from Gulf of Mannar
to Palk Bay through Adam’s Bridge.

In northeast monsoon, the values of longshore transport rate was relatively
low along the spit facing Gulf of Mannar and negligible in Palk Bay. It is noticed that
the long shore sediment transport rate was considerable (>10 X 103 m3/month) in
January between Uthalai and Mukkuperiyar. The sediment transport direction was
consistently towards west in Gulf of Mannar and east in Palk Bay.
In fair weather period, the longshore sediment transport was low along the
spit facing Gulf of Mannar and also Palk Bay. The transport direction was observed to
be westerly near the tip facing Gulf of Mannar. It shows that in February, April and May
the sediment drifts from Palk Bay to Gulf of Mannar and the net quantity is found to be
8000m3, 6000 m3, 20000 m3 respectively. Consequently, in March, June, July, August
and September, it drifts from Gulf of Mannar towards Palk Bay and the respective
quantities are 8000 m3, 35000 m3, 10000 m3, 4000 m3 and 1000 m3 respectively.
There was no significant movement of sediment observed during October to January.
It means that during southwest monsoon, the sediments move from Gulf of Mannar to
Palk Bay and during fair weather period from Palk Bay to Gulf of Mannar. No
noticeable exchange due to wave induced longshore transport takes place in
northeast monsoon. It is noticed that over a period of one year, a net volume of 24000
m3 sediments as a wave induced longshore transport move from Gulf of Mannar to
Palk Bay around Adam’s Bridge.
The study indicates that, in general, the entire study region between Tuticorin
and Ariyaman including the Rameswaram Island experiences very low sediment
transport rate compared to the rest of Indian east coast. The east coast between
6
Chennai and Paradeep experiences a gross transport rate of more than 1x10
m3/year. On the otherhand, along the study region, it remained always less than
0.1x106 m3/year, which shows only 10 percent of the rest of the Indian east coast.
The sediment transport rate is practically negligible throughout the year,
particularly between Valinokkam and Kondugal in Gulf of Mannar, and between
Arimunai and Ariyaman in Palk Bay. The geomorphological formation of inner part of
Gulf of Mannar and the presence of many offshore islands are the main reasons for
wave attenuation and reduction in sediment transport.
The coastal segment between Tuticorin and Valinokkam experienced
relatively higher sediment transport rate during northeast monsoon, but remained calm

during the rest of the year. However, the small stretch between Vember and
Naripaiyur experienced relatively higher sediment transport rate also during southwest
monsoon. The only coastline between Uthalai and Arimunai experienced relatively
higher sediment transport rate both during southwest monsoon and fair weather
period, with relatively low sediment transport during northeast monsoon.
The direction of sediment transport during southwest monsoon remained
easterly between Tuticorin and Arimunai except near Kondugal and Dhanushkodi,
where it was in opposite direction, i.e. towards west. Due to the reversal of sediment
transport direction near Kondugal, the easterly transport gets deposited in the vicinity
of Pamban Pass, Kursadi Tivu, Kovi Tivu and Shingle Tivu. Once again the easterly
transport along Vedalai terminates near Dhanushkodi which would cause the
formation of shoals in the vicinity off Arimunai. Such formation of submerged shoals
was observed south off Arimunai during the study period. The prevalence of easterly
transport at Arimunai might cause part of the sediments deposited as shoals to
migrate towards Adam’s Bridge and enter into Palk Bay. This processes of sediment
migration were noticed close to Adam’s Bridge. Hence a small proportion of littoral drift
deposited during southwest monsoon close to Pamban Pass and Arimunai has the
tendency to enter Palk Bay.
During the northeast monsoon, the sediment transport rate was very low
moving in southerly direction between Tuticorin and Valinokkam and it was negligible
between Valinokkam and Mandapam. Between Kondugal and Arimunai, the transport
was relatively low in westerly direction. It implies that there will be a deposition of
littoral drift in the vicinity of Pamban Pass. Due to low littoral drift taking place during
northeast monsoon, the quantity of sediments entering Gulf of Mannar from Palk Bay
will be much lower than the quantity moving from Gulf of Mannar to Palk Bay during
southwest monsoon.

During fair weather monsoon, the sediment transport rate along the entire
study region except between Uthalai and Arimunai remains negligible. The sediment
transport between Uthalai and Arimunai exists relatively low in westerly direction for
which the source of sediment is expected from Palk Bay though Adam’s Bridge.
Due to low sediment transport rate prevailing in the study region, which
comprises of about 10 percent compared to the rest of Indian east coast, the volume
of sediment exchange is expected to be low. During southwest monsoon, the sizeable
portion of littoral drift from west coast passing around Kanyakumari is seen getting
deposited before reaching Tuticorin. This deposited sediment is supplied back for the
westerly transport during northeast monsoon. Such deposition is evidenced from the
occurrence of large beach deposition is evidenced from the occurrence of large beach
deposits and elevated dunes along Tiruchendur – Manapad region. Similarly, the
southerly transport along the east coast during northeast monsoon gets deposited
between Vedaranyam and Manmelkudi in Palk Bay, which is supplied back to the
littoral drift cycle during southwest monsoon.
Thus the study indicates that there is a break in the chain of littoral drift at
Tuticorin on the south and Vedaranyam is relatively low and there exits limited quantity
of exchange through Pamban Pass and Adam’s Bridge.
It signifies that the region around Adam’s Bridge forms as significant sink for
the littoral drift. The prolonged accumulation may lead to the emergence of new
islands. In case of occurrence of cyclones in Gulf of Mannar, such prolonged
deposition of sediments move north and enter in Palk Bay through Pamban Pass and
Adam’s Bridge. Once the sediments enter Palk Bay, the environment favours
immediate deposition. Hence the occurrence of cyclones in Gulf of Mannar and the
associated high northerly waves might exchange more sediments from the southern
part of Peninsular India to northern part of east coast. Similarly any cyclones moving in
Palk Bay, would generate large southerly waves and transport sizeable amount of
deposited sediments into Gulf of Mannar. In the event of absence of cyclones, the
deposition will increase causing the enlargement of sand
spit and shoaling across Adam’s Bridge, but the order of sediment exchange will be
limited.

2.2.3.2 Spit Configuration
The numerical modelling study for the region around Rameswaram indicates
that due to tidal currents, in southwest monsoon (june-september), the sediment
transport is 6000 m3 and 30000 m3 through pamban pass and Arimunai respectively
moving from Gulf of Mannar to palk Bay. The same phenomenon continued in fair
weather period (February- May) indicating 3000 m3 and 16500 m3 through pambam
Pass and Arimunai respectively moving from Gulf of Mannar to Palk Bay.
On the other hand ,during northeast monsoon( October-january), about
15000 m3 and 21000 m3 of sediments are being transported through Pamban Pass
and Arimuani respectively from Palk Bay to Gulf of Mannar. It shows that in an annual
cycle, a net exchange of 6000 m3 of sediment is found to move from Palk Bay Pass to
Gulf of mannar through Pamban Pass and 25,500 m3 of sediment moves from Gulf of
Mannar to Palk Bay through Arimunai. The modelling study indicated that the volume
of sediment exchange due to tidal current (25, 500 m3 /year) is very close to the
volume being transported through littoral drift in breaker zone (24000 m3/ year).
Pamban pas (m3) Adam’s Bridge (m3)
Season
Southwest monsoon -6000 -30000
(June to September)
Fair weather - 3000 - 16500
(February to May)
North-East monsoon 15000 21000
(October to January)
6000 m3 /year -25500 m3 /year
Net
(-) = Towards Palk Bay
(+) = Towards Gulf of Mannar
The annual gross longshore sediment transport rate along the study region
remained less than 0.1 x 106 m3 /year, which shows only 10 percent of the rest of the
Indian east coast.

In February, April and May the wave induced littoral drift is taking place from
Palk Bay to Gulf of Mannar and the net quantity is found to be 8000 m3, 6000 m3, 2000
m3, respectively. Consequently, in March, june July, August and September , it drifts
from Gulf of Mannar to Palk Bay and the quantity is 8000 m3, 35000 m3, 10000 m3,
4000 m3, and 1000 m3, respectively. There was no significant movement of sediment
between October and January. Over a period of one year, a net volume of 24000 m3, /
year sediments moves from Gulf of Mannar to Palk Bay. Adam’s Bridge forms as
noticeable sink for the littoral drift. The prolonged accumulation leads to the
emergence of new islands.
The modelling study indicates that over an annual cycle, the net volume of
sediment exchange due to tidal current is 6000 m3, form Palk Bay to Gulf of Mannar
through pamban pass and 25500 m3, from Gulf of Manar to Palk Bay through
Arimunai.
The satellite imageries show that the spit gets deflected towards palk Bay
during southwest monsoon indicating erosion on Gulf of Mannar side and deposition
on Palk Bay side. During northeast monsoon, the spit gets deposited on Gulf of
Mannar side and eroded in Palk Bay side, but the over all length increased by 150 m
towards Adam’s Bridge.
The sand spit extended 455 m in seven years indicating an average growth of
65 m in a year. the width increased 200 m at 1 km distance from the tip.
2.2.4 Geological Strata along Navigational Channel in Adams Bridge
Area
NSDRC with the help of M/s Indomer Coastal Hydraulics Pvt. Ltd, has taken
up jet probe drilling operations on the sea floor to identify the type of geological strata
along the navigational canal.
Scope
i) to carry out wash boring at 3 locations at 2m , 3m and 5m water depths along
the proposed navigational route,
ii) to carry out drilling upto 12 m penetration into the sea floor or till reaching the
hard strata whichever is minimum,
iii) to collect wash boring sediment samples, and

iv) to analyze the soil classifications of the collected sediment samples.
Methodology
Drilling jet probe was constructed on board a vessel with 5 HP pumps driven
by diesel generator. The outlet of 75-mm diameter pipe was connected to 30 m long
hose. To the other end of the hose, a drilling jet, having a tapered mechanism varying
from 75 mm to 40 mm diameter was attached. During the operation of pump at full
capacity, the jet velocity remained about 10 m/s. The jet was capable of penetrating
into sea floor up to a depth of 12 m in case of sandy bed. The jet drilling was carried
out at 3 points in each location to confirm the type of strata. During the last attempt of
jet drilling, divers collected sediment samples. These sediment samples were
analyzed for grain size distribution using sieve shaker with sieves of different mesh
sizes.
The locations of the jet probes are shown in Fig.2.41. The details of the
locations are given in the table below:
Co-ordinates
Bore Water depth Depth of drilling
hole No. (m) (m)
Latitude Longitude
09O08.364′N 79O27.675′E
BH1 1 12
09O08.811′N 79O27.868′E
BH2 2 12
09O10.109′N 79O28.008′E
BH3 5 12
BH1 : The sediments collected at different layers (S1-surface, S2-2.5m, S3-
5.0m, S4-7.5m, S5-9.0m and S6-12.0m) at BH1. The composition of sediments shows
that it consists of light brownish Grey loose medium sand from 0 to 7.5 m, medium
sand with debris shells and shellsand from 7.5 to 12 m. The grain size distributions for
sediment collected at different layers are shown in Figs. 2.42a, 2.42b and 2.42c.
BH2 : The sediments collected at different layers at (S1-surface, S2-2.5m,
S3-5.0m, S4-6.5m and S5-11.0m) BH2. The composition of sediments shows that it
consists of grayish medium sand from 0 to 5 m, silty sandy from 5 to 6.5 m and
medium sand with whitish shell sand from 6.5 to 11.0 m. The grain size distribution for
sediment collected at different layers is shown in Fig. 2.43a through 2.43c.
BH3 : The sediments collected at different layers (S1- surface, S2-0.7m to
8.5m, S3-8.5m to 10m and S4-10.5m to 12.7m) at BH3. The composition of sediments

shows that it consists of fine sand from 0 to 0.7m, silty medium sand with shell debris
from 0.7 to 8.5m, little silty coarse sand from 8.5 to 10.5 m and silty medium sand from
10.5 to 12 m. The grain size distribution for sediment collected at different layers is
shown in Figs. 2.44a through 2.44b.
2.2.5 Bathymetry and Shallow Seismic Survey In Gulf of
Mannar and Palk Bay Area
Bathymetry Mapping
Any changes in sea floor may be the result of sea-level variation or to a
change in the elevation of land surface. Changes in absolute water-surface levels are
worldwide due to the interconnectivity of the oceans and are termed eustatic changes.
Changes in the absolute level of the land are localized. They may be due to tectonic
adjustments or due to adjustments caused by their distribution of weight on the land
surface. As and when sedimentation or ice build-up occurs, such changes are known
as isostatic. A rise in the sea level or down warping of land would involve the opposite
movements of sea and land. Synonymous with positive and negative changes are the
forms of sea-level transgression and regression, although in many cases these terms
also refer to the horizontal movement of the shoreline associated with vertical changes
of sea level. Recent depth contour map of 1999 has been compared with bathymetry
map of 1975; it reflects that the seafloor level has decreased along the coastal areas
and around the islands in the study area. It may be either due to emergence of land or
lowering of sea level (due to tectonism) and sediment deposit. In very few places,
particularly at river mouths and in island areas, the sea floor level has increased,
which may be due to erosion caused by anthropogenic activities.
The average depth reduction of seafloor along the coast of the study area has
been estimated as 0.51m over a period of 24 years. The average decrease and
increase of depth around the islands in the study area have been calculated as 0.56m
and 0.38m respectively. Assuming that the rate of change of depth of sea floor is
uniform over a year, the rate of decrease of depth is estimated as 0.021m/year along
the coast and 0.023 m/year around the island, and also the rate of increase of depth
as 0.015 m/year around the island. The annual sediment deposit on Gulf of Mannar
sea floor is about 0.001m/year (Basanta Kumar Jena 1997), or 0.024m for a period of
24 years. As found from the present study, the decrease of depth for the period of 24
years (1975 to 1999) is about 0.51m. Sedimentation accounts for about 0.024m in the

total of 0.5 from clearance depth. The remaining 0.486 m reduction in depth may be
due to emerging of land or lowering of sea level (by tectonic activities). Based on the
above data, the rate of emerging of land or lowering of sea level can be estimated as
0.02m/year. Bathymetry maps of Gulf of Mannar (1975) and Bathymetry Map of
Tuticorin Coastal Region is given in Figs. 2.45-2.46 respectively. The general
bathymetry in Palk Bay area is shown in Drawing 2.1.
2.2.5.1 Bathymetry and Shallow Seismic Survey in Area Identified for
Channel in Adam’s Bridge
An area of 4 km x 20 km showing bathymetry less than 12 m was identified
for detailed bathymetry and seismic survey in Adam’s Bridge area based on admiralty
chart. This location is shown in the Fig. 2.47. Bathymetry survey was carried out in
May 2003 and February 2004 over 100 line km across the 20 km by 4 km area. (Fig.
2.48).
Out of the total survey area of 4 km x 20 km marked for bathymetry and
shallow seismic survey, micro bathymetry survey was also carried out in 4 km x 4 km
as per the requirement. Bathymetry and shallow seismic survey (five lines) in 4 x 20
km section in Adam’s Bridge Area, beyond which safe navigation route is available on
both sides of the Adam’s bridge, has been completed. The charts detailing bathymetry
and geotech profile are shown in drawings listed as Drawing 2.2 to 2.11.
The bathymetry survey of 4 km x 4 km. area also has been undertaken and
completed during the second phase of the survey work. The bathymetry is shown in
Drawing 2.12.

Site survey Line Pattern
Bathymetry and shallow seismic survey conducted in 4 kms x 20 kms area
along the proposed ship canal longitudinal lines spaced at 1 km intervals. Lines run in
000O /180O direction. Echosounder, sub bottom profiler has run on all survey lines up
to the safe navigation limit.
• The Bathymetry and shallow seismic survey of 4 km x 10 km (five
lines) on south side of Adam’s Bridge
Bathymetry
For study propose 5 imaginary lines separated by 1 km distance have been
considered to explain bathymetry pattern across Adam’s Bridge covering 20 km
length. Thus each line is 20 km long stretching north-south across the Adam’s Bridge
as shown in Fig. 2.48. Line no. one is boundary of box facing Pamban island where
line 5 is boundary towards medial line for fishing.
a) Line No. 1
The bathymetry along the line no.1 reveals that the seabed from the North
end of the survey line to the South end gradually increases with depths ranging from
0.8 m to 11.8m. The bathymetry is presented in Drawing 2.2.
b) Line No. 2
The bathymetry along the second line reveals gradual fall in the seabed with
depths varying between 1.4m at the North end and 12.7 m on the South end of the
line. The bathymetry of this route is presented in Drawing 2.3.
c) Line No.3
The bathymetry along the 3rd line reveals gradual fall in the seabed with
depths varying between 2.4m at the North end and 11.7 m on the South end of the
line. The bathymetry of this route is presented in Drawing 2.4.
d) Line No.4
The bathymetry along the line no.4 reveals gradual fall in the seabed with
depths varying between 2.9m at the North end and 11.8 m on the South end of the
line.

The bathymetry of line no.4 is presented in Drawing 2.5.
e) Line No. 5
The bathymetry of line no.5 is presented in Drawing 2.6.
The bathymetry along the line no.5 reveals gradual fall in the seabed with
depths varying between 3.8m at the North end and 7.9 m on the South end of the line.
Shallow Stratigraphy
a) Line No. 1
Information regarding shallow geological conditions is presented in Drawing
2.2.
The shallow geological successions within the window examined by the digital
data along this route can be differentiated into essentially four units.
The shallow seismic survey could not be carried out in less than 5m depth as
it was not feasible to take the survey boat in that area due to depth limitation and
presence of heavy breakers in the area. The note to that effect is shown in the
geological profile panel on the chart
Unit A is the uppermost of the sedimentary sequence and recorded all along
the surveyed corridor. The high acoustic transparency of this unit without any well-
defined internal reflectors indicates that it is comprised of soft sediments. Maximum
thickness of this unit along the proposed route is 0.5 m sub-seabed.
Underlying Unit A is Unit B. This unit is characterised by chaotic reflection
configuration. The surface and internal reflectors show medium acoustic impedance to
the seismic energy indicating more strength of material. This unit is interpreted as
comprising very high density to high density sands.Thickness of this layer varies
between 1 m to 3.5m.
Underlying Unit B is Unit C which can be identified from records with high
acoustic reflectivity from the surface. This unit is interpreted as medium to low density
sand. The thickness of this layer varies between 2m to 4m.

b) Line No. 2
Information regarding shallow geological conditions on line no.2 is presented
in Drawing 2.3. The shallow geological successions within the window examined by
the digital data along this route can be differentiated into essentially four units.
The shallow seismic survey could not be carried out in less than 5m depth as
it was not feasible to take the survey boat in that area due to depth limitation and
presence of heavy breakers in the area. The note to that effect is shown in the
geological profile panel on the chart.
Unit A is the uppermost of the sedimentary sequence and recorded all along
the survey corridor. The high acoustic transparency of this unit without any well-
defined internal reflectors indicates that it is comprised of soft sediments. Maximum
thickness of this unit along the proposed route is 0.3 m.
Underlying Unit A is Unit B. This unit is characterised by chaotic reflection
conFiguration. The surface and internal reflectors show high acoustic impedance to
the seismic energy indicating more strength of material. This unit is interpreted as
comprising completely to very high density sands. Thickness of this layer varies
between 0.5m and 1.5m.
Underlying Unit B is Unit C which can be identified from records with medium
acoustic reflectivity from the surface. This unit is interpreted as comprising completely
of very high density sands.Thickness of this unit varies from 1.0m to 2.5m.
Underlying Unit C is Unit D which can be identified from records with low
acoustic reflectivity from the surface. This unit is interpreted as comprising low density
loose sands. Thickness of this unit varies from 0.5m to 2m
c) Line No. 3
Information regarding shallow geological conditions of line no.3 is presented
in Drawing 2.4.
The shallow geological successions within the window examined by the digital
data along this route can be differentiated into essentially three units.
The shallow seismic survey could not be carried out in less than 5m depths
as it was not feasible to take the survey boat in that area due to depth limitation and

presence of heavy breakers in the area. The note to that effect is shown in the
geological profile panel on the chart.
Unit A is the uppermost of the sedimentary sequence and recorded all along
the survey corridor. The high acoustic transparency of this unit without any well-
defined internal reflectors indicates that it is comprised of soft sediments. Thickeners
of this unit along the line is 0.40 m sub seabed.
Underlying Unit A is Unit B. This unit is characterised by chaotic reflection
configuration. The Surface and internal reflectors show high acoustic impedance to the
seismic energy indicating more strength of material. This unit is interpreted as
comprising very high density sands. Thickness of this layer along the line is 0.5m to
3.5m.
Underlying Unit B is Unit C which can be identified from records with medium
to low acoustic reflectivity from the surface. This unit is interpreted as comprising
medium to low density loose sands. Thickness of this unit varies from 0.5m to 1.5m.
d) Line No. 4
Information regarding shallow geological conditions is presented in Drawing
2.5.
The shallow geological successions within the window examined by the digital
data along this route can be differentiated into essentially three units.
The shallow seismic survey could not be carried out in less than 5m depths
as it was not feasible to take the survey boat in that area due to depth limitation and
presence of heavy breakers in the area. The note to that effect is shown in the
geological profile panel on the chart.
Unit A is the uppermost of the sedimentary sequence and recorded all along
the survey corridor. The high acoustic transparency of this unit without any well-
defined internal reflectors indicates that it is comprised of soft sediments. The
maximum thickness of this unit along the line is 0.30 m.
Underlying Unit A is Unit B. This unit is characterised by chaotic reflection
conFiguration. The surface and internal reflectors show high acoustic impedance to
the seismic energy indicating more strength of material. This unit is interpreted as

comprising of high density sands. Thickness of this layer varies between 0.5 and 1.5
m.
Underlying Unit B is Unit C which can be identified from records with medium
to low acoustic reflectivity from the surface. This unit is interpreted as comprising of
medium to low density sands. The thickness of this unit along the line varies between
2.5 m to 3.5 m.
Underlying Unit C is Unit D which can be identified from records with low
acoustic reflectivity from the surface. This unit is interpreted as comprising of low
density sands. The thickness of this unit along the line varies between 2 m to 3 m.
e) Line No. 5
Information regarding shallow geological conditions is presented in Drawing
2.6.
The shallow geological successions within the window examined by the digital
data along this route can be differentiated into essentially three units.
The shallow seismic survey could not be carried out in less than 5m depth as
it was not feasible to take the survey boat in that area due to depth limitation and
presence of heavy breakers in the area. The note to that effect is shown in the
geological profile panel on the chart
Unit A is the uppermost of the sedimentary sequence and recorded all along
the survey corridor. The high acoustic transparency of this unit without any well-
defined internal reflectors indicates that it is comprised of soft sediments. Maximum
thickness of this unit along the proposed route is 0.50 m.
Underlying Unit A is Unit B. This unit is characterised by chaotic reflection
configuration. The surface and internal reflectors show high acoustic impedance to the
seismic energy indicating more strength of material. This unit is interpreted as
comprising of very high density sands. Thickness of this layer varies between 0.5 and
4.5 metres.
Underlying Unit B is Unit C, which can be identified from records with medium
to low acoustic reflectivity from the surface. This unit is interpreted as comprising of
medium density sands. The thickness of this unit along the line varies between 2m to
3m.

The Bathymetry and shallow seismic survey of 4 km x 10 km (five lines) on
north side of Adam’s bridge
a) Line No. 1
The bathymetry of the rout is presented in Drawing 2.7. The bathymetry
along the line no.1 reveals that seabed from the north end of the survey line to the
south end gradually falls with depths from 7.0 m to 1.4 m.
b) Line No. 2
The bathymetry of the route is presented in Drawing 2.8. The bathymetry
along the second line reveals gradual fall in the seabed with depths varying between
9.1 m at the North end and 2.1 m on the south end of the line.
c) Line No. 3
The bathymetry of line no. 3 is presented in Drawing 2.9. The bathymetry
along the 3rd line reveals gradual fall in the seabed with depths varying between 9.5m
at the North end and 2.5 m on the South end of the line.
d) Line No. 4
The bathymetry of line no.4 is presented in Drawing 2.10. The bathymetry
along the line no. 4 reveals gradual fall in the seabed with depths varying between
10.1 m at the North end and 2.8 m on the South end of the line.
e) Line No. 5
The bathymetry of line no. 5 is presented in Drawing 2.11. The bathymetry
along the line no. 5 reveals graduals fall in the seabed with depths varying between
10.1 m at the North end and 2.8 m on the south end of the line.
Shallow Stratigraphy
a) Line No. 1
Information regarding shallow geological conditions is presented in Drawing
2.7. The shallow geological successions within the window examined by the digital
data along this route can be differentiated into essentially four units.
Unit A is the uppermost of the sedimentary sequence and recorded all along
the surveyed corridor. The high acoustic transparency of this unit without any well-
defined internal reflectors indicates that it is comprised of soft sediments. Maximum
thickness of this unit along the proposed route is 0.5 m sub-seabed.

Underlying unit A is Unit B. This unit is characterised by chaotic reflection
configuration. The surface and internal reflectors show medium acoustic impedance to
the seismic energy indicating more strength of material. This unit is interpreted as
comprising very high density to high density sands. Thickness of this layer varies
between 1m to 4m.
Underlying unit B is Unit C which can be identified from records with high
acoustic reflectivity from the surface. This unit is interpreted as medium to low density
sand. The thickness of this layer varies between 1 m to 3 m.
Underlying unit C is D which can be identified from records with low acoustic
reflectivity from the surface. This unit is interpreted as low density loose sand. The
thickness of this layer varies between 1 m to 2m.
b) Line No. 2
Information regarding shallow geological conditions online in Drawing 2.8.
The shallow geological successions within the window examined by the digital data
along this route can be differentiated into essentially four units.
Unit A is the uppermost of the sedimentary sequence and recorded all along
the survey corridor. The high acoustic transparency of this unit without any well-
defined internal reflectors indicates that it is comprised of soft sediments. Maximum
thickness of this unit along the proposed route is 0.5 m.
Underlying Unit A is Unit B. this unit is characterised by chaotic reflection
configuration. The surface and internal reflectors show high acoustic impedance to the
seismic energy indicating more strength of material. This unit is interpreted as
comprising completely to very high density sands. Thickness of this layer varies
between 1.5 m and 3m. At places bottom of this unit is not discenrnible from records.
Underlying Unit B is Unit C which can be identified from records with medium
acoustic reflectivity from the surface. This unit is interpreted as comprising medium to
low density sands. Thickness of this unit varies from 1 m to 3 m.
Underlying Unit C is Unit D which can be identified from records with low
acoustic reflectivity from the surface. This unit is interpreted as comprising low density
loose sands. Thickness of this unit varies from 1 m to 2 m.

c) Line No.3
Information regarding shallow geological conditions of line in Drawing 2.9.
The shallow geological successions within the window examined by the digital data
along this route can be differentiated into essentially three units.
Unit A is the uppermost of the sedimentary sequence and recorded all along
the survey corridor. The high acoustic transparency of this unit without any well-
defined
internal reflectors indicates that it is comprised of soft sediments. Thickness of this unit
along the line 0.50 m sub seabed.
Underlying Unit A is Unit B. This unit is characterised by chaotic reflection
conFiguration. The surface and internal reflectors show high acoustic impedance to
the seismic energy indicating more strength of material. This unit is interpreted as
comprising very high density sands. Thickness of this layer along the line is 1 m to 3
m.
Underlying Unit B is Unit C which can be identified from records with medium
to low acoustic reflectivity from the surface. This unit is interpreted as comprising
medium to low density loose sands. Thickness of this unit varies from 3 m to 5 m.
d) Line No.4
Information regarding shallow geological conditions is presented in Drawing
2.10. The shallow geological successions within the window examined by the digital
data along this route can be differentiated into essentially three units.
Unit A is the uppermost of the sedimentary sequence and recorded all along
the survey corridor. The high acoustic transparency of this unit without any well-
defined internal reflectors indicates that it is comprised of soft sediments. The
maximum thickness of this unit along the line is 0.50m.
Underlying Unit A is Unit B. This unit is characterised by chaotic reflection
conFiguration. The surface and internal reflectors show high acoustic impedance to
the seismic energy indicating more strength of material. This unit is interpreted as
comprising of high density sands. Thickness of this layer varies between 1 and 3 m.
Underlying Unit B is Unit C which can be identified from records with medium
to low acoustic reflectivity from the surface. This unit is interpreted as comprising of

medium to low density sands. The thickness of this unit along the line varies between
1 m to 3m.
Underlying Unit C is D which can be identified from records with low acoustic
reflectivity from the surface. This unit is interpreted as comprising of low density sands.
The thickness of this along the line varies between 1m to 3m.
e) Line No. 5
Information regarding shallow geological conditions is presented in Drawing
2.11. The shallow geological successions within the window examined by the digital
data along this route can be differentiated into essentially three units.
Unit A is the uppermost of the sedimentary sequence and recorded all along
the survey corridor. The high acoustic transparency of this unit without any well-
defined internal reflectors indicates that it is comprised of soft sediments. Maximum
thickness of this unit along the proposed route is 0.50 m.
Underlying Unit A is Unit B. This unit is characterised by chaotic reflection
configuration. The surface and internal reflectors show high acoustic impedance to the
seismic energy indicating more strength of material. This unit is interpreted as
comprising of very high density sands. Thickness of this layer varies between 1 and
3.5 meters. The maximum thickness being around 1022250 northing.
Underlying Unit B is Unit C, which can be identified from records with medium
to low acoustic reflectivity from the surface. This unit is interpreted as comprising of
medium density sands. The thickness of this unit along the line varies between 2 m to
3 m.
Under lying unit C is unit D which can be identified from records with low
acoustic reflectivity form the surface. The unit is interpreted as comprising of low
density loose sand. The thickness of this unit is 1 m to 1.5 m.
The bathymetry survey of the proposed five survey lines across the Adam’s
Bridge reveals that the seabed has gradual slope from North towards south and also
East to West with depths between 11.3 m at the North East corner of the survey area
and 1.4 m at the south west corner of the survey area and 9.0m at North west corner
to 4.4m at South East corner of the survey area. The seabed is thus seen deepening
from southwest corner of the survey area to North East corner of the survey area.

Unit A is the uppermost of the sedimentary sequence and recorded all along
the surveyed corridor and comprised of soft sediments. Unit B is interpreted as
comprising completely to moderately with very high density sand to medium density
sand. Underlying Unit B is Unit C which is interpreted as low density sand. No
anomalies associated with any type of rock is evident from the records up to the
penetration of about 6 to 7m.
In view of very high density sands lying below a very thin layer of soft
sediments in the entire area of survey the penetration of the seismic system has been
restricted to that in the sand to a maximum depth of about six to seven meters,
however, no rocky strata was observed in the entire survey area up to the depth of
penetration.
2.2.5.2 Bathymetry Survey of Area of 4 km. X 4 km.
The bathymetry survey of 4km. x 4km. area at 50m interval reveals that
depths are gradually decreasing from South-West corner of the survey area to South-
East corner of the survey area with maximum depth of 6.3m around the South-West
corner to a minimum of 0.6m depth around South-East corner of the survey area in
general with considerable depth variation in between. The depth contours drawn at 1
m interval in the survey area reveal that almost all contours run in approximately in
North West-South East direction (Drawing 2.12).
A shallow patch showing strip of exposed land area runs from North West
corner of the survey area in approximately towards the South East corner of the
survey area. This stretch of the area has all along heavy breakers breaking almost all
the times from the South West as well as from the North East directions making it
extremely difficult to negotiate the area.
2.2.5.3 Bathymetry and Seismic Survey along the Channel in Palk Bay Area
Hydrographic survey along the proposed channel in Palk Bay area was
undertaken by National Hydrographic Office (NHO) during January 25-February 18,
2004. The survey was carried out 250 m on either side of the line joining points
indicated in Drawing 2.13 detailed below :
9O21′26″N 79O21′37″E
C
9O40′30″N 79O25′30″E
D

9O58′20″N 79O33′30″E
E
10O11′30″N 80O12′30″E
F
In addition NHO covered points A and B adjoining Adams Bridge Area at
9O08′43″N, 79O2539″E and 09O13′42″N and 79O28′50″E in addition to data collected
by NSDRC. The survey was undertaken using long range HF Sercel Differential
Global Positioning System, Echo Sounder Atlas Deso 20 with duel frequency
transducers of 210/33 k3H, Smart Acoustic Current meter, Geostar
SB-216 full spectrum sonar system to measure sediment thickness.
The seabed of the complete area comprise sand and mud with few broken
shells. The depth contours in the area are in agreement with those depicted on the
existing navigation Chart 358 (Drawing 2.1). The area between point C to E (refer
Drawing 2.13) has depth more than 12 m and thus no dredging will be required.
However area north of point E and south of point C will require to be dredged to 12 m
depth. Since the sea bed is mud and sand capital dredging would not be difficult
proposal. Sub bottom profiler indicates that there is some hard strata under the soft
sediment (Figs. 2.49-2.50).
The tides in this area are variable. Both semidiurnal and diurnal tides were
observed. The range of tide varied from 0.4 to 0.7 m at the spring. Current in the area
is along N-S direction and speed varied from 0.1 m/sec to 1.0 m/sec.
2.2.6 Selection of Route in Adam’s Bridge Area
The area for navigation route in Adam’s Bridge area was selected keeping in
view the proximity to international Medial line for fishing as well as national park
boundary. The purpose of selecting the stretch under study was to avoid / minimize
impacts on marine national park. The selected area is approximately 10 km away from
Arimunai tip and about 20 km away from Sringle island which is a part of national park.
The bathymetry data collected in this stretch was used to identify possible alignment of
route within the block. Zeroing down on to the option of 10.7 m draft and 300 m width
of channel availability or creation of 12 m deep channel with minimum dredging
requirement was considered as a critical parameter to arrive at alignment across the
Adam’s Bridge. From the assessed bathymetry, line 2 was considered as route for
navigation as dredging requirement will be minimum. This line is also at least 4 km

away from medial line. The details on quantity and quality of dredged spoil likely to be
generated by dredging in this route is discussed under chapter on environmental
impacts.
2.2.7 Navigation Route in Palk Bay and Palk Strait
The ships after traveling through the channel in Adam’s Bridge area will tread
through available navigation depth in Palk Bay.
It could be seen that channel further needs to be created in Palk Strait area
where the bathymetry varies from 7.0 m to 10.8 m. Based on the available chart the
exercise for computing of dredging requirement to attain 12.0 m depth has been taken
up and is explained in chapter on Environmental Impacts. The
selection of route is guided by minimum dredging requirement and distance from
medial line. The proposed channel alignment with its bathymetry is shown in
Fig. 2.51.
2.2.8 Computation of Dredged Material
Based on bathymetry data, quantity of dredged spoil with 12 m depth and 300
m with for a proposed channel is about 38x106 m3 in Adam’s Bridge Area and is about
44x106 m3 for Palk strait area. Thus total capital dredging required for
continuous navigation channel of 12 m depth will be of the order of 82 million m3. The
quality of dredged spoil in Adam’s Bridge area is mostly sand with small percentage of
silt and clay. The quality of dredged spoil in Palk strait area also comprise clay and
sand upto 12 m as per data collected by NHO Dehradun.
2.3 Environmental Setting in Project Area
The sea coast stretching along the proposed canal project region is broken by
a few minor rivers like Agniar, Ambuliar, Vellar, Koluvanaru, Pambar, Manimukta nadi,
Kottangarai aru and Vaigai draining vast areas of irrigated lands. In the Gulf of Mannar
along the coast there are 21 islands (Table 2.6) which have been declared as National
Marine Park by the Tamilnadu Forest Department and the Ministry of Environment and
Forests, Government of India.

The Palk Bay (PB) and the Gulf of Mannar (GOM) are considered biologically
rich and are rated among the highly productive seas of the world. The Gulf of Mannar
harbours one of the richest biodiversity of living resources which have evolved in the
past millennia. Primarily due to its semi enclosed nature, seclusion, shallowness, and
having more or less stable temperature regimen, presence of multiple niches,
recycling and enrichment of nutrients amply derived from land drainage by the rich
variety of coastal, sedimentary, medowan, reef and paar biota, the Gulf of Mannar has
acquired ecological uniqueness, biodiversity, pluralism alongwith endemism. It is a
natural heritage, and is often called the 'Biologist's Paradise'. Through an executive
communication from the Secretary to the Government of India, Ministry of
Environment & Forests to the Chief Secretary, Government of Tamilnadu, the Gulf of
Mannar Marine Biosphere Reserve (GOMMBRE) has been notified in 1989. There is,
however, no legislation as yet on the biosphere reserve either at the national or at the
state level.
The Gulf of Mannar is endowed with a combination of ecosystem including
mangroves, seagrass and coral reefs, supporting over 3,600 species of plants and
animals. Its biodiversity is considered globally significant. The Gulf of Mannar islands
constitute a resting place for birds migrating to and from Sri Lanka. Approximately 168
types of birds use the islands in the Gulf as a resting place while migrating or as
wintering and molting grounds. All five species of marine turtle nest in various
locations in the Gulf of Mannar. Dolphins are more common here than in any other
region in the Bay of Bengal. The endangered dugong uses many of the islands as
browsing grounds. Marine life also includes many coloured coral fishes, eels,
molluscs, and stomatopoda. Sea anemones, crabs, starfish, sea urchins and
numerous other organisms are found in the Gulf of Mannar waters.
There are no hills on any of the islands, most of which are less than three
metres above the level of the high water springs. The islands are irregular in shape,
with spits and partially enclosed bays. Sandy beaches are located on many of the
islands and along the mainland coast. Fringing and patch coral reefs are located in the
Gulf of Mannar. The eastern side of the islands has the greatest expanse of living
coral reefs, because human exploitation of the reefs is concentrated on the northern
and western sides. The vegetation on the islands is not uniformly spread and generally
consists of thorny shrubs. Mangroves are located on Shingle, Krusadai, Pullivasl,

Poomarichan, Manoli and Manoliputti islands. Tree species such as palmyra,
casuarina, coconut, and tamarind grow on Shingle, Krusadai, Hare and Nallathanni
islands. Most of the islands have been significantly deforested. Some reforestation is
also taking place.
Located within the Biosphere Reserve, Krusadai island exemplifies the
biological significance of the area. The island harbours three species of seagrasses
endemic to the Gulf of Mannar. Representatives of every animal phyla known (except
amphibians) occur on this island. The island harbours a unique, endemic organism
called \"balanoglossus\" (Ptychodera fava), a living fossil which links vertebrates and
invertebrates.
Supporting the Gulf's biodiversity are its extensive and diverse assemblage of
seagrass. Six of the world's twelve seagrass genera and eleven of the world's fifty
species, occur in the Gulf. The Gulf harbours the highest concentration of seagrass
species along India's 7,500 km of coastline. These seagrass beds are some of the
largest remaining feeding grounds for the globally endangered dugong (Dugong
dugon). The seagrass beds also provide feeding areas for all the five species of
marine turtles, the Green (Chelonia mydas), the Loggerhead (Caretta caretta). Okive
Ridleys (Lepidochelys olivacea). Hawksbill (Eretmochelys imbricate) and Leather
backs (Dermochelys coriacea). Many species of crustaceans, molluscs, gastropods
and fishes have been observed to inhabit the seagrass beds.
The Gulf's seagrass communities are valuable habitats for commercially
harvested species, particularly the green tiger prawn Penaeus semisulcatus, which is
extensively harvested for the export market. Holothurian, an endemic echinoderm
found in abundance in the Gulf of Mannar, is extensively exploited for export to Japan
and other Southeast in the Gulf of Mannar, is extensively exploited for export to Japan
and other Southeast Asian countries as a highly, priced food item for human
consumption. The economically viable species of seaweeds such as Hypnea,
Gelidiella, Gracilaria, Stoechosperum, Hydrochlathrus, Clathratus, Padina, Caulerpa
are largely distributed in the Gulf of Mannar. In addition, ornamental shells, chanks,
and pearl oysters are exploited in the Gulf. Sea fans and seaweeds are exported for
industrial and decorative purposes.

The Gulf of Mannar harbours a total of 128 species of coral belonging to 37
genera. Coral reefs serve as the spawning grounds for fisheries, seagrass beds as
nursery grounds, and mangroves and shelters form a unique component of life-
support system of coastal biodiversity that relates to global benefits and local needs.
Seventeen different mangrove species occur within the biosphere reserve area. The
coastal mangrove Pemphis acidula is endemic to the Gulf of Mannar. Coastal
mangroves are important nursery habitats and biodiversity reservoirs in coastal areas.
Both the reserve area and the adjacent coastline have been degraded to
some extent by overuse and pollution as evidenced by the declining catch/effort ratios
in the fisheries, the absence of significant numbers of herbivorous fish on coral reef
areas, low coral cover and widespread growth of green marine algae in coraline areas
and absence of large vegetation on many parts of the islands. Some areas of the
coast also show visible effects of pollution, most of it emanating from the mainland.
In Palk Bay area, there are ecologically sensitive coastal areas harboring
mangrove forests, marshlands etc. Point calimere a wild life and bird sanctuary is in
coastal areas adjoining palk strait. This sanctuary is situated at southern end of
Nagapattinam district at 100 17’ - 100 22’ N and 790 25’- 79052’ E. The sanctuary may
be divided into three divisions: the point calimere forest; the GVS which includes the
mangrove forests at Muthupet and the mangroves of TRF. It is the breeding ground or
nursery for many species of marine fishes which are vital to the fisheries of the coast.
It is a marine-coastal wetland with a wide diversity of habitats and ecological features,
including: intertidal salt marshes, forested wetlands, mangroves and brackish to saline
lagoons. The sanctuary has been designated as a Ramsar site in November 2002.
• The GVS is one of the largest waterbodies and major wintering ground
for water birds in southern India. The forests of point Calimere are also
rich in both resident and migratory species of forest birds. A total of 257
species of birds have been recorded from the Sanctuary of which 119
are waterbirds and 138 forestbirds.
• The wetland supports the vulnerable species spoonbill sandpiper
‘Eurynorhynchus pygmaeus’ and grey pelican ‘Pelecanus philippensis’
according to the IUCN Red List.

• It supports about 30,000 flamingos, 200-300 endangered grey pelican,
the endangered Asian dowitcher, the rare spoonbill sandpiper and tens
of thousands of other waterbirds. A total of 119 waterbird species have
been recorded from the area.
• The wetland is the breeding ground or nursery for many species of
marine fishes which are vital to the fisheries of the coast. GVS is the
spawning and/or nursing ground for commercially important prawns,
crabs and fishes. Eastern part of the GVS harbours 23 fish species,
mainly mullets, whereas the Mullipalam Lagoon at Muthupet has a
more direct influence of the sea and harbours more marine species of
fish, some 20 species.
Fauna
Some of the major waterbird species are the greater flamingo and the lesser
flamingo, spot- billed pelican, spoonbilled sandpiper, Asian dowitcher, whitebellied
seaeagle, brahminy kite and osprey. Landbirds include paradise flycatcher, Indian
pitta, Rosy starling, Blyth reed warbler, crested serpent eagle and brown shrike.
Fourteen species of mammals have been reported from the Sanctuary. The larger
mammals are the blackbuck, spotted deer, wild boar and jackal. The flying fox resides
in large groups on trees in the point Calimere forest and the mangrove forest at
Muthupet. The blackbuck of point Calimere represents one of the three isolated
populations of blackbuck existing in Tamil Nadu with the other populations in the
Guindy National Park and near Satyamangalam.
A sanctuary provides for local income and employment specially in areas of
salt production, forest produce, firewood and fish products. About 35,000 fishermen
and agriculturists live around the sanctuary.

3. Marine Environment
The data generated by NEERI in locations along the 60 km long alignment
and further verified at select locations in vicinity of Gulf of Mannar, Adams bridge and
Palk Bay besides secondary data from CMFRI, CECRI is used for describing the
marine environment. The locations 1 to 4 in Palk Bay and 5 to 8 in Gulf of Mannar
were selected in the vicinity of Adams bridge area which will be dredged to achieve
required draft and 9 and 10 near Tuticorin Port area (Fig. 3.1). The details of the
locations for which data on physico-chemical parameters, phytoplankton,
zooplankton and benthos was collected, are presented in Table 3.1. The depths at
these locations are in the range of 3 m to 23 m, the maximum being in the Tuticorin
port area and the minimum near the Adam's Bridge.
Apart from primary data, secondary data was collected from various
government departments like Department of Ocean Development, Central Marine
Fisheries Research Institute (CMFRI), Central Electro-chemical Research Institute
(CECRI), Forest Department, Fisheries Department, Wildlife Department, Non-
Governmental Organisation (NGO), Project Authority etc.
3.1 Physico-chemical Characteristics
Marine Water
The samples were collected 20 cm below the water level to assess physico-
chemical quality of marine water. The physico-chemical characteristics of marine
water at various locations along the route are presented in Tables 3.2 and 3.3. The
pH of sea water is alkaline and ranges between 8.0 to 8.2.
All living organisms are dependent upon oxygen in one form or another to
maintain the metabolic processes that produce energy for growth and reproduction.
Dissolved oxygen (DO) plays an important role in precipitation and dissolution of
inorganic substances in water and it is in the range from 3.2 to
5.7 mg/L.

The concentration of heavy metals viz. iron, selenium, chromium, zinc, lead,
cadmium, nickel, boron, manganese and copper in marine water samples are below
detectable limits except for iron, boron and arsenic. The concentration of boron is in
the range of 2.29 mg/L - 3.06 mg/L. High concentrations of arsenic (0.07-0.13 mg/L)
are observed at locations near Tuticorin port area that may be attributed to arsenic
used in making wood preservatives/ paints for ships.
It is well known that diatoms and other organisms deplete silicate from the
lighted zone of the sea, and that, on the death of the organisms, the silicate may
either re-enter in solution or may reach the bottom. The silicate content in the marine
water varies from 0.003 mg/L to 0.017 mg/L. No significant variation in salinity is
observed in surface and bottom samples (Fig. 3.2). An inverse relationship between
salinity and silicate is found to exist at some of the locations (Fig. 3.3). The nitrate
concentration varies from 0.78 mg/L to 1.1. mg/L.
Sediments
The data on physico-chemical parameters and metals of the sediments is
presented in Table 3.4. The sediments comprise loose black mud, fine clayey sand
with dead shells, coarse white sand with dead shells, coarse sand slightly reddish
with shell fragments and hard corralline bottom covered with coarse sand and shell
pieces. The particle sizes of sediments are depicted in
Fig. 3.4.
The organic carbon content of the sediment ranges from 0.06% to 0.09%.
The total Kjeldahl nitrogen (N), total phosphorus (P2O5) and sulphates (SO4) are in
the range of 0.02% to 0.11%, 0.02% to 0.84% and 0.06% to 0.75% respectively. Oil
and grease are present at all locations in the sediments. Concentrations of heavy
metals such as iron and arsenic are high in sediments. Cadmium and cobalt are also
detected in sediments.
Many animals that live buried in sediment are selective deposit feeders,
lifting and sucking food particles out of the mud; and others feed unselectively on
sediment deposits. These include different molluscs, sea cucumbers and many
worms. Fine muds, easily suspended by bottom currents, are generally not a
satisfactory substrate for filter feeders. Muds and clays, however, are well suited to
organisms that feed unselectively by ingesting sediments because the smaller

particles normally contain more organic matter. Such detritus supports bacteria and
meiofauna that are food for deposit feeders.
Excess organic material in the sediment may cause oxygen depletion in the
near-bottom waters that is intolerable to most benthic animals. About 3% of organic
matter in the sediment appears to be optimal for deposit-feeding bivalves. Predatory
forms, such as brittle stars, are more abundant where organic carbon content is
higher (Gross, 1982). In areas of red clay deposits, where sediment accumulation is
slow and deposits contain less than 0.25% of organic carbon, filter feeders are
conspicuous.
Published data on abiotic characteristics of sediment from the Gulf of
Mannar and the Palk Bay is very limited. The fine black mud of Palk Bay collected a
decade back from a site north of Adam's Bridge and on analysis it indicated to
contain - silica 55.0%, carbonate of lime 3.5%, phosphate of lime 2.25%, ferric oxide
4.10%, alumina 15.80%, magnesia 2.75% and organic matter and water 16.60%.
The mineral composition was of sand grains, quartz, tourmaline, felspar, zircon,
corundum, kyanite, garnet, mica (biotite), rutile, and ilmenite. At some places
patches of black grains containing magnetic iron were also observed by earlier
workers (Salvadori, 1960, 1961).
3.2 Biological Characterstics
Primary Productivity
Primary productivity in the sea is dependent on photosynthesis of green
plants, principally of the phytoplankton, with possible minor contribution from very
few species of photosynthetic bacteria. The energy necessary for the process, which
gets accumulated as chemical energy in the organic matter, is derived from sun light.
The level of primary productivity is associated with the concentration of nutrients.
The data on primary productivity in the Gulf of Mannar and the Palk Bay is presented
in Table 3.5.
The gross primary productivity values varied from 143 to 472 gC/m3/day
between the stations. The mean values of 205 and 223 mgC/m3/day for the Palk Bay
and the Gulf of Mannar respectively are comparable. Literature reveals that in the
Gulf of Mannar off Mandapam there are two peaks of production - one in April-May
and another in October. During a study period of two years, the primary productivity

was found to range from 77 mgC/m3/day in April with an average of 200 mgC/m3/day
(Prasad and Nair 1963). Thus, the mean value of primary productivity in the Gulf of
Mannar has not been altered significantly during a span of over two decades.
It is further reported that in the near shore areas where the euphotic zone
used to be about 6 m due to turbidity, the productivity was 1.2-1.5 gC/m2/day which
is equal to the annual gross productivity of about 450 gC/m2. While further inside the
sea where the euphotic zone is deeper (upto 15-40 m), the average daily productivity
used to be 3-5 gC/m2 (Nair 1970). The average primary productivity values in central
ocean basins and coastal zones of the world were estimated at 50 and 100 gC/m2/yr
respectively (Ryther 1969). Thus, the shallow regions of the Gulf of Mannar and the
Palk Bay constitute one of the most productive regions of the world. This means it is
clear that turbidity adversely affects primary productivity.
Marine Organisms
A complex food web is present in GOMMBRE due to high diversity of flora
and fauna present in the area (Fig. 3.5). The details of marine organisms recorded in
Gulf of Mannar during different periods are given in Table 3.6.
The prawns Penaeus semisulcatus feed on a variety of food items viz.,
polychaetes, crustaceans, molluscs, diatoms, foraminiferans and radiolarians
(Thomas, 1980). Four species of Foraminifera, namely Fissurina ventricosa, Nonion
grateloupi, Nonionella auricula and Bolivina variabilis were found in the stomach
contents of the prawn, Penaeus semisulcatus. (Ameer Hamsa, 1981). The two
species of Chirocentrus i.e. C. nudus and C. dorab found in the Palk Bay and Gulf of
Mannar appear to be diurnal predators preying mostly on fishes (Luther, 1985).
These are some of the examples of marine organisms present in food web in Gulf of
Mannar.
However, the biodiversity in Gulf of Mannar is now under severe threat due
to destruction of sensitive ecosystems like corals and seagrass through
indiscriminate and intensive trawling, coral mining, dynamite fishing, commercial
fishing of specific fauna such as sea fans, chanks, sea cucumber, sea horse and
endangered species like dugongs and turtles. The similar cases are of gargonids in
the Gulf of Mannar and the sacred chanks and the pearl oyster Pinctada fucata
along south-east coast, the sping lobsters Panulirus sp. and deep sea lobsters off

south-east coast (Dehadrai et al., 1994). A survey of 20 islands in Gulf of Mannar
during 1977-81 revealed the extensive destruction of fauna and flora by human
interference and require immediate action for flora and fauna (Mahadevan & Nayar,
1983). These activities have depleted the resources and reduce the biological wealth
of this region. The status of the biota of Gulf of Mannar is depicted in Table 3.7.
Phytoplankton : Phytoplankton are mostly unicellular organisms which are either
solitary or colonial. These autotrophs synthesise organic material from inorganic
substances in the presence of sunlight through the process of photosynthesis.
Consequently, the depth of light penetration decides the volume of sea water in
which photosynthesis can occur. Phytoplankton provide food to herbivores and
hence form a major link in the food chain. In turbid waters of many coastal areas, the
compensation depth is exiguous and the phytoplankton contribution to primary
productivity is minimal. Conversely, in deep clear waters, the compensation depth is
considerable and the contribution of the phytoplankton to primary productivity is
significant.
126 species of Phytoplankton were reported (Table 3.8).
Diatoms : 97 species (33 genera)
Dinoflagellates : 16 species (6 genera)
Blue-green algae : 7 species (5 genera)
Green algae : 3 species (3 genera)
Others : 3 species (3 genera)
The population density varied from 34000 to 86000 cells/liter.

Maximum Diversity Index values of phytoplankton for 19 islands are shown
in Table 3.9 and Fig. 3.6. The values ranged from 2.708 to 3.583 showing moderate
diversity of phytoplankton in study area.
The blooming of Trichodesmium a blue-green alga has been observed in
the Palk Bay and in the northern portion of the Gulf of Mannar (Tables 3.10 and
3.11). This alga on blooming forms clumpy aggregates. The maximum value for this
alga is 0.8 x 106 per m3 which indicate that the blooming occurs in the northern part
of the Palk Bay and extends to south of the region. It is of interest to note that since
plankton move alongwith water current, it indicates that depending on the prevailing
current conditions the algal cells do not drift to the inshore waters of Rameswaram.
The blooming results in low diversity values, as indicated at several locations.
However, diversity index values exceeding 2.0 are also observed at some of the
locations.
In the Palk Bay and the Gulf of Mannar the phytoplankton peaks do not
seem to follow monsoons strictly as do zooplankton. In general, in a year 2 to 3
phytoplankton peaks have been recorded in the earlier years, mostly in January
(prominent), April-May and October-November. At times during July-August too, a
minor peak had been observed (Prasad, 1954, 1956). Blooming or swarming of
unicellular biota, observed in these studies, were Trichodesmium theibauti,
T. erythraeum, Noctiluca, Ceratium, Gymodinium and rarely Gonyaulax. The studies
had further revealed considerable variation from year to year in abundance,
composition and succession in phytoplanktons.
Zooplankton : This is a very important group in the aquatic ecosystem, acting as the
primary consumer and ultimately serving as the natural food sources for many
aquatic organisms including fishes. Depending on the season, the plankton
community shows pronounced variation in its character and composition. This is
because many are planktonic throughout their life, while others are so only during
part of their life.
Approximately 360 species of zooplankton were reported (CMFRI, 1998).
The population density of zooplankton varied from 8000 to 65000 nos/cu.m and the
species belonging to the following phyla were commonly found : Protozoa,
Coelenterata, Ctenophora, Annelida, Chaetognatha, Mollusca, Echinodermata,

Arthropoda, Chordata and other minor phyla. The details of distribution of
zooplankton during Oct. 98 to Aug 99 in Gulf of Mannar is presented in Table 3.12.
Shannon Weaver Diversity Index of zooplankon in Palk Bay and Gulf of Mannar
along with other coastal waters in India is recorded in Table 3.13.
In the present survey, the diversity and various groups of organisms present
at different locations are presented in Tables 3.14 and 3.15. While copepoda form
the most prominent group, the diversity index varies between 2.67 and 4.24. The
stations which are close to the shore usually exhibit low index values. The data
indicates higher diversity among zooplankton in the offshore waters. In the Palk Bay
and the Gulf of Mannar the zooplankton have been observed to show a bimodal
cycle, with a minor peak between January and March, and a primary peak during
September - October due to the monsoon conditions (Krishna Kartha 1959).
Copepods and chaetognaths reach their maximum when the salinity was low. But
there were few copepods and lucifor when molluscan larvae and fish eggs
constituted high percentages (Marichany, Siraimeetan , 1979).
Seven deep sea decapod crustaceans belonging to sections Penaeidae (4
species), Caridae (2 species) and Astacidae (1 species) are found from the Gulf of
Mannar (Thomas, 1979).
Maximum Diversity Index values for zooplankton in 21 islands of Gulf of
Mannar are shown in Table 3.16 and Fig. 3.7. Highest diversity was observed at 11
islands and moderate diversity (beween 2 to 3) at other 8 islands.
Benthos : The organisms which inhabit the bottom of an aquatic body are called
benthos. Many of them are sessile, some creep over a burrow in mud. The quality
and quantity of animals found at the bottom are not only related to the nature of
substrate but also to the depth, and the kind and quality of the other associated
aquatic biota. Their number and distribution also depend upon physico-chemical and
biological characteristics of water. Benthic organisms of different groups have been
recorded from Gulf of Mannar. (GOI, DOD and ICMAMPD, 2001) (Table 3.17).
The sediment samples collected from different stations in the Gulf of Mannar
and the Palk Bay were passed through 500 µ mesh sieve and again through 45 µ
sieve for segregation of macrobenthos and meiobenthos respectively, as described
below.

Macrobenthos : The details of biota observed along with the sedimentary conditions
of benthos at various locations are presented in Tables 3.18 and 3.19. Some of the
locations are rich in flora and fauna. The diversity index values are observed to be
above 3. In general, contrary to the zooplankton, the near shore stations exhibited
higher diversity indices than those of offshore. Most of the offshore stations have
indices around 1.0. Altogether 78 varieties of macrobenthos from 14 groups have
been recorded. Details of the major groups of macrobenthos recorded in the study
area are presented hereunder.
Meiobenthos : Meiofauna comprises animals intermediate in size between
micro and macrofaunal organisms. In benthic environment, meiofauna consumes
unicellular organisms such as bacteria, microscopic algae and protozoa; in turn
meiofauna are consumed by macrofaunal organisms such as shrimps, gobids,
juveniles of flat fish etc. Meiofauna associates fluctuate seasonally with respect to
density, biomass and species composition in different locations of the sea. The
meiofauna in terms of number vary from 0-132 and in biomass 0-19.40 mg per 100
cm-2 of sediment (Table 3.20). The meiofauna comprises larval polychaetes,
nematodes, other worms, and shrunken bodies probably of juvenile tunicates,
actinids etc.
Corals (Coelenterate) : The animals in the Phylum Coelenterata have a
radial symmetry, and food capture by means of specialized stinging cells. Amongst
the three classes of this phylum, the class anthozoa comprises the coral and seafan
which are ecologically important in the Gulf of Mannar Marine Biosphere Reserve
(GOMMBRE).
The coral is a colony of tiny sea anemone-like polyps living together in
thousands and secreting a calcareous skeleton of calcium carbonate which they
extract from sea water. Coral reefs are diverse and a vulnerable ecosystem
characterised by a complex interdependence of plants and animals. Reefs are the
centres of high biological productivity, sites of CO2 sink and sources of huge deposits
of CaCO3. The ecological significance of coral reefs is outlined below :
Coral reef constitutes one of the most valuable natural heritages
–
of the GOMMBRE.
Healthy coral reef provides a home for a number of species
–

comprising a large number of individual colourful fishes,
invertebrates and seaweeds.
Coral reef provides an ideal feeding ground for various marine
–
animals.
They also serve as a nursery and breeding ground for many
–
invertebrates and enhance the level of fishery production.
Coral reef absorbs CO2 and converts it into CaCO3, thereby,
–
reducing the CO2 in the global environment.
They protect the sea shore from erosion.
–
The coral formations in and around Rameshwaram indicate local
emergence and are presumed to be formed around 4000 years B.C. (Rao, 1990).
Around Rameshwaram Island, northwest of Pamban, enormous coral stages were
found. They are still seen at low tide level, having a height from
1.5 to 3 m (Rajamanickam, Loveson, 1990)
On analysis of data on corals in the Gulf of Mannar and the Palk Bay,
solitary coral at each of 3 locations, 1 & 2 have been observed, locations 2 and 1
possess only 1 and 3 types of macrofauna respectively. Smaller size and poor
density of coral might be the principal factors for not attracting other flora and fauna
in these locations. In general, the presence of corals along the proposed alignment
of Sethusamudram ship canal appears to be negligible.
The reefs of Gulf of Mannar are fringing or patchy thriving in shallow waters
(0.2-5.0m) around almost all islands. Most of the framework of coral reef is made up
of dead or semi fossilised Porites spp. Literature survey indicates that about 128 (42
endemic) species of corals have been recorded (Pillai, 1986 and CMFRI, 1998) and
the coral reefs lying on the southern side of the island are more dense and exhibit
greater species diversity than the reefs on northern side. The dominant genera are
Pocillopora, Porites, Acropora, Montipora, Favia, Favites, Goniopora, Goniastrea,
Platygyra, Echinopora, Galacea, Turbinaria, Leptoria, Poavona and Pochyseris. The
details of distribution pattern of corals and live coral percentage is presented in
Table 3.21 and Figs. 3.8-3.9.

Gorgonids are observed in the Palk Bay while in the Gulf of Mannar these
are recorded only near the islands. Gorgonid community is popularly known as
“Flowers of underwater gardens”. Fourteen species of gorgonids were recorded
(Tomas and George, 1987). The dominant genera were Subergorgia, Plexauroides,
Muricella, Echinomuriceae, Echinogorgia, Thesea, Heterogorgia, Junceela and
Gorgonella.
For diversity, density and distribution of corals in the Palk Bay and the Gulf
of Mannar, the available information is debatable and needs detailed systematic
investigation. While Gopinadha Pillai (1969, 1971) listed 20 and 94 species of corals
in the Palk Bay and the Gulf of Mannar respectively, Asir Ramesh and Kannupandi
(1997) recorded 25 species of corals from a specific area like Vellaperukkumunai
reef in the Palk Bay. Santhanam and Venkataramanujam (1996) identified 18
species of stony corals only at Tuticorin (Gulf of Mannar), and Petterson Edward and
Asir Ramesh (1996) reported 32 species of corals from Pulli island alone in the Gulf
of Mannar. However, studies carried out by Zoological Survey of India (Anonymous,
1998) revealed only 21 species of corals in the Gulf of Mannar Marine Biosphere
Reserve.
Maximum Diversity Index values of corals in 21 islands of Gulf of Mannar
are shown in Table 3.22 and Fig. 3.10. The diversity is good (>2) on 9 islands while
it is very less (0.69) at Appa island and 0 at Vilanguchalli island. Other islands have
moderate diversity.
Quarrying of corals for various purposes has been in vogue in the Gulf of
Mannar and the Palk Bay for a long time. Three factories in Tirunelveli district were
using corals as a raw material for their products. Mandapam and Tuticorin were the
two important bases for the collection and stacking of the coral stones. While (Patel
and Bhaskaran, 1978), it has been stopped totally at Mandapam after establishment
of the National Marine Park Authority. However, in Tuticorin area quarrying of corals
still goes on, and the landing has been estimated at 5000 t/yr (Anonymous 1998).
The areas wherein live coral reefs are prominent are shown in Fig. 3.9. It is
believed that inspite of large scale removal of corals, still there may be areas
wherein the endemic corals are available. As per earlier records, there were 53
species of endemic stony corals inhabiting this area. The reefs of Manauli area

appear to be very important. It has been postulated by Stoddart (1973) that the
modern reef growth in the region began about 5000 years ago.
Sea fan (Coelenterata) : The Sea fan is yet another colonial form, but it branches
only in one plane and the branches may fuse with each other to form a 'fan'. White or
cream-coloured polyps may grow on a base of contrasting maroon colour, attached
to stones by a broad disc-like holdfast. The colourful sea fans have long been
objects of attraction to man.
Foraminifera : 51 species (2 endemic) of foraminiferans (CMFRI, 1998) were
reported and the dominant genera were Trochammina, Robulus, Nonion, Operculina,
Bolivina, Bulimina, Streblus, Poroeponides and Cancris.
Sponges (Porifera) : 275 species (31 endemic) of sponges were reported from Gulf
of Mannar and Palk Bay (Thomas, 1986).
Order No. of Species
Keratosida : 22
Haplosclerida : 39
Poecilosclerida : 74
Halichondrida : 31
Hadromerida : 43
Epipolasida : 17
Choristida : 30
Carnosida : 19
The dominant genera were Heteronema, Spongia, Dysidea, Haliclona,
Callyspongia, Spirastrella and Cliona.
Sponges, although at a casual glance look like plants, are animals, living
singly or in colonies. They have no fixed shape, and form flat encrustations on
stones in the region of strong waves. In the crevices, these sponges are found
associated with many animals, ranging from tiny crabs and brittle star to bivalve
molluscs. Sponges show commensalism as several crustaceans, worms, molluscs
and fishes live in the internal cavities of sponges for protection against enemies, and
also act as a shelter bed.

Regarding macrobenthos, altogether 77 sponges comprising 11 genus have
been recorded in the region. The density is higher (3333 ha-1) in Tuticorin area,
followed by 533 and 440 ha-1 in the Palk Bay and northern side of the Gulf of Mannar
respectively. The estimated sponges along the proposed alignment of
-1
Sethusamudram canal are 1050 ha . Upreti and Shanmugaraj (1997) recorded 275
species of sponges inhabiting the Palk Bay and the Gulf of Mannar area. Sponges
prefer both the island biosphere as also the open sea-ward areas, preferably upon
30 metre depth (CMFRI 1998).
Boring sponges form the major group among the marine organisms causing
considerable destruction to the reef system. The 'bores' left by the sponges weaken
the reef making it more susceptible to wear and tear caused by the waves and the
associated impact. There are altogether 20 known species of boring sponges in the
Gulf of Mannar and the Palk Bay.
Polychaeta : 75 species were recorded (CMFRI, 1998). The dominant genera were
Iphione, Harmothoes, Eurythoe, Chloeia, Eulalia, Syllis, Ceratonereis, Perinereis,
Eunice, Marphysa, Onuphis and malacoceros.
Nematoda : 9 species were recorded (Ayyakkannu, 1974). The dominant genera
were Anticoma, Halalaimus, Oncholainmus and Chromadora.
Crustacea : The crustaceans rank second in the diversity of fauna in the coaral reef
ecosystem and many of them are exploited for commercial purpose. The knowledge
about marine crustaceans in incomplete. They consist of crabs, lobster, prawns, and
shrimps.

Planktonic and Larval forms
Group Species recorded
Copedods 223
Cumacea 10
Amphipods 52
Ostracods 57
Isopoda 18
Decapod larva 8
The dominant groups were Acrtia, Acrocalanus, Centropages,
Canthocalanus, Eucalanus, Microsetella, Oithona, Lucifer and penaeid larvae.
Mollusca : The Mollusca includes a variety of most conspicuous, invertebrates such as
bivalves, gastropods and cephalopods of which the class gastropoda covers the largest
number of diversified forms. The gills of molluscs act as a filter to collect microscopic food
particles. While mussels, oysters etc. come under bivalvia, cephalopods including squids,
octopus etc. are primarily pelagic forms. The benthic molluscs have economic significance as
under.
Bivalves, cephalopods and gastropods are delicious sea food
–
items locally and in Southeast Asian countries.
Pearls of high value as gems are produced by the pearl oyster of
–
the genus Pinctada under the family Pleriidae.
The sacred chank (Xancus pyrum) are much in demand for the
–
manufacture of bangles, ornamental and decorative materials.
Oyster shell is used to produce lime for poultry and other uses.
–
Molluscs absorb CO2 and convert it into CaCO3, thus reducing the
–
level of CO2 in the global environment.
The operculum of gastropods is used for manufacturing perfumes
–
and making incense sticks.
731 species of molluscs belonging to three classes namely Bivalvia,
Gastropoda and Cephalopoda were recorded (Satyamurthi, 1952; CMFRI, 1969).

Bivalvia : Arca, Modiolus, Lithophaga, Perna, Isognomon,
–
Malleus, Pteria, Pinctada, Pinna, Cardium, Crassostrea, Meretrix,
Donax and Tellina.
Gastropods : Trochus, Turbo, Nerita, Littorina, Turritella,
–
Cerithidea, Janthina, Tibia, Strombus, Cypreaea, Bursa, Tonna,
Chicoreus, Xancus, Babylonia and Hemifusus.
Cephalopods : Sepia, Sepiella, Loligo and Octopus.
–
Information on the two important groups of molluscs, viz. pearl oyster and
chank outlined hereunder.
Pearl oysters : Pearl oysters are available in large numbers from 24 groups of 87
paars in the Gulf of Mannar. Pinctada fucata yields gem quality pearls for which the
Gulf of Mannar is famous from time immorial. The other species found are P.
chemnitzii, P. anomioides, P. atropurpura, and P. margaretifera. Of the 24 groups of
pearls, 14 occur between the shore and proposed canal in the Gulf of Mannar (Fig.
3.11). The proposed alignment of sethusamudram canal passes through the groups
I, VIII, XI, XII and XIII. Out of 14 paars in these five groups, the maximum number of
seven is in group XI which is located close to Tuticorin. However, five specimens of
P. fucata in 25 m2 area are found far away from the proposed alignment of the canal
and close to the island at the northern side of the Gulf of Mannar.
Considerable mortality of young pearl oyster, Pinctada fucata, was noticed
on the oyster beds in Gulf of Mannar due to predation by gastropods, Cymatium
cingulation and Murex virgineus (Chellam, et al., 1983).
Chanks : The sacred chank, Xancus pyrum is another resource of economic
importance in the region. The demand for chanks from the bangle industry is about
2.5 million pieces per year. The present supply, which meets only about 40% of the
demand, comes mainly from the Gulf of Mannar. On an average 9 x 105 and 49 x 103
sacred chanks are exploited per annum from the Gulf of Mannar and the Palk Bay
respectively (Devraj and Ravichandran 1988). Among the chanks, the variety acuta
(or jathy in Tamil), found in the Gulf of Mannar fetches higher prices than the rest
available elsewhere. The dominant variety present in the Palk Bay is obtusa. The
chank habitats, which are within 5-25 m (often upto 35 m) depth are shown in Fig.
3.12. Areas with high population density have also been depicted in the Figure.

Usually chanks prefer fine sandy areas with rocky beds, wherein nereids abound.
The sinistral freak is also available from this area.
Echinoderms : Echinoderms are common and conspicuous organisms of the
intertidal region. Their body structure is modified to live on different substrate such
as rocky shores, sandy beaches, muddy flats, algal beds and coral reefs. Their
concentration in the coral reefs is maximum (James, 1982). The phylum
Echinodermata comprises the classes asteroidea, ophiuroidea, echinoidea, crinoidea
and holothuroidea representing starfish, brittle star sea urchin, feather star and sea
cucumber respectively, and all occur in the Gulf of Mannar and the Palk Bay. Dried
holothurians, marketed as beche-de-mer are used as food items. These are
delicious and nutritious containing 35-52% of protein. Other classes of
echinodermata have decorative/ ornamental use.
264 species belonging to five classes namely Crinoida, Asteroidea,
Ophiuroidea Echinoidea and Hologhuroidea have been recorded (James, 1985,
CMFRI, 1998). The major genera were:
Crinoidea : Capillaster, Comatella, Comanthus, Comaster,
–
Heterometra, and Tropiometra.
Asteroidea : Astropecten, Craspidiaster, Goniodiscaster,
–
Stellaster, Culcita, Pentaseraster, Linckia, Asterina and
Echinaster.
Ophiuroidea : Ophiacits, Macrophiothrix, Ophiogymna,
–
Ophiothela and Ophiothrix.
Echinoidea : Astrophyga, Salmacis, Echinometra and
–
Echinodiscus.
Holothuroidea : Holothuria, Stichopus, Pentacta, Hemithyone
–
and Synaptula. Economically only Holothuroidea (12 species) are
exploited on a commercial scale for export.
The processed sea cucumber (beche-de-mer) is entirely exported mainly to
Singapore and Hong Kong yielding about Rs. 1 crore per annum (CMFRI, 1998 :
personal communication). Holothuria scabra is mostly (90%) exported followed by H.
spinifera, H. atra, Actinopyga echinites, A. miliaris and Bohadschia marorata. The

marketable size of H. scabra is about 40 cm in length and 500 g in weight. Tuticorin,
Kelakkarai, Periyapattinam, Vedalai, Pamban, Rameswaram, Tondi, Deviptinam and
Tiruppalaikudi are the important centres of sea cucumber. Flourishing export market
for the processed sea cucumbers has increased their exploitation. Over 90% of
beche-de-mer exported from India, is from the Palk Bay and the Gulf of Mannar of
which the contribution of the former and the latter is 60 and 30% respectively. Sea
cucumbers are mostly collected by skin divers in shallow waters from 2-10 m depth
(James 1994). Presently, operation of a modified trawl net called Chanku madi yields
good catches of sea cucumbers alongwith chanks (Xancus pyrum). The harvest
composition of this gear is Xancus pyrum (61.22%), sea cucumbers (20.4%), rays
(Amphotistus kuhlii) (16.33%) and starfish, sea shells and small fishes (2.04%).
Holothuria being detritus feeders are found among the marine macro-algae and
seaweeds. Their habitats in the Gulf of Mannar and the Palk Bay are shown in Fig.
3.13.
Prochordata : All the three groups of prochordata, viz. hemichordata,
cephalochordata and urochordata comprising 1,6 and 59 species respectively were
recorded in the Gulf of Mannar and the Palk bay. These organisms are considered
as the connecting link between invertebrates and vertebrates.
Hemichordata : The limited publications on this group has indicated the occurrence
of the only species Ptychotera fava (balanoglossus) in the Gulf of Mannar (Upreti
and Shanmugaraj, 1997). Balanoglossus in the Gulf of Mannar is in a very much
restricted area, viz. Kunthugal in the Pamban island and Kurusadai island. The
presence of the animal is discernibel by the characteristic iodoform odour present in
the mud. Balanoglossus are zoologically a very interesting group from evolutionary
point of view and their importance is enhanced by their rarity.
Cephalochordata : Another group of prochorates of significance is the
cephalochordates which measure 4-5 cm in length. Though the animals belonging to
this group are limited in number but are not as rare as the balanoglossus. In the Gulf
of Mannar and adjacent areas 6 species are reported to be available. Except
Branchiostoma pelagicum which is pelagic, as the name itself indicates, the rest are
benthic, habitating depths ranging from 5 to 25 m. The Gulf of Mannar and the
adjacent marine areas seem to be the western most geographical limit of their
distribution.

Urochordata : The Palk Bay and the Gulf of Mannar have good resources of
tunicates. These jelly-like organisms are mostly sedentary and contain variety of
bioactive compounds useful as drugs.
Fisheries
Marine capture fishery is the major economic activity of Gulf of Mannar. The
total area of Gulf of Mannar under Indian Exclusive Economic Zone is about
15000 sq. km. and commercial fishing is done in about 5500 sq. km. within 50 m
depth. Both mechanized and non-mechanized fishing units are mainly responsible
for exploitation of sea fish resources in Gulf of Mannar (Kasim and Hamsa, 1987).
Fishing in the Palk Bay and the Gulf of Mannar is multigear, multispecies
and is carried out throughout the coast of mainland and the Pamban island. Within
the study area, there are 87 fish landing centres between the south of Point Calimere
and Pamban in the Palk Bay, and 40 centres in the Gulf of Mannar from Pamban to
Tuticorin Harbour (Table 3.23).
Fishes : The Gulf of Mannar and the Palk Bay with their peculiar topography are
noted for their faunal diversity and richness. Mahadevan and Nayar (1967) made
detailed observations on the rock bottom of this area and described its faunal
diversity. Gulf of Mannar is one of the best regions in the Indian subcontinent in fish
biodiversity richness. The Shannon Weaver Diversity Index (H’ values) for the
ornamental fishes around each island in the Gulf of Mannar exceeds 2.5 in 2/3 of the
islands. The variation in its value with species richness and density is depicted in
Table 3.24. Although over 600 species of fishes, crustaceans and molluscs (out of
which no. of fish species is 441) are reported (Anonymous 1998), to support the
fishery in these regions, the commercially important species (200 species out of total
441 fish sp.) (Table 3.25) are limited in number.
The chief fisheries are the pelagic sardines, seer fish, tunas, mackerel,
sharks, caranids, barracudas, wolf herring, full and half beaks, the demersal perches
such as sweetlips, groupers, rock-cods, snappers, goat fishes, croakers, sharks,
rays, skates, coral fishes, threadfin, breams, silverbellies, the shell fishes like
chanks, squids, cuttlefish shrimps, crabs and lobsters. Most of these resources are
commercially exploited by mechanised trawlers.

There was overfishing of silverbellies in 1973-74 and 1974-75 when the
effort far exceeded the optimum level. (Venkataraman et.al., 1981). Pair trawling
carried out in Palk Bay yielded large catches of Rainbow sardines (Dussumieria) and
pomfrets (Pampus argenteus). (Pillai, Sathiadhas, 1982). Fishery of the swimming
crab Portunus pelagicus Linnaeus is done on large scale along the Palk Bay and
Gulf of Mannar. Vedalai is found to be the most productive centre for crabs (Hamsa,
KMSA, 1978).
The sunfish M. oxyuroptenus is found in the Gulf of Mannar (Devaraj,
Nammalwar and Thiagarajan, 1976). Silverbellies (Leiognathus jonesi) form an
important demersal fishery of India particularly on the coasts of southern maritime
states, the annual average catch amounting to about 3% of the total marine fish
catch in India (Annam, Raja, 1981). The marine mammals – dolphins and dugongs
form a part of fishery. The smaller cetaceans that are caught along the Indian coast
are Stenella longirostris, Delphinus delphis, Jousa chinensis and Tursiops truncates.
Annually about 25 dugongs are caught in the Gulf of Mannar and Palk Bay and
about 250 dolphins are caught along the Indian Coast (Mohan, 1987).
Shore seines, boat seines, trawl nets and hooks and lines are the principal
gear operated. The shore seines are of two types namely Kara valai and Olavalai.
The former is operated with the help of vallam fitted with out board engines and is
mainly used for capturing small pelagic fishes while the latter is operated with the
help of nonmechanised vallam craft for capturing small shrimps and small pelagic
fishes. Boat seines are operated using vallam with inboard engine. Specialised gears
are also used such as chala valai for small pelagic fishes, paru valai for perches and
tunas, thirukkai valai for rays, nandu valai for crabs and lobster etc. Traps are used
to catch reef dwellers such as groupers, snappers, lobsters,shrimps etc. Shrimp and
fish trawl nets are operated to capture a variety of demersal fishes such as
silverbellies, carangids, perches, pomfrets, ogatfishes, rays, prawns etc. Among
hooks and lines, longolines are used for hooking perches, catfish, sharks etc. and
troll lines for scombroids, fishes, sharks, carangids etc. Depending on the tide and
fishing season kalamkatti valai is operated at night on the shores of the islands for
catching shore fishes and mullets.
The commercial importance of fish is either as food for human being or as
fishery by-products like fish oil from sardines, liver oil from sharks and skates,

processed fish skin from sharks, rays and bigger groupers and fish meal from small
sized low value fish for use in cattle and poultry farms. The commercially important
species include sardines, mackerel, anchovies, seerfishes, tunas, ribbon fishes,
elashmobranchs, perches, catfishes, silver bellies, goatfish, lizard fishes, ribbon
fishes, mullets, barracudas, penaeid and non-penaeid shrimps, lobsters, crabs,
cephalopods, bivalves and gastropods.
Capture Fishes : 441 species (Dorairaj, 1997) were reported in the following orders,
namely Lamniformes, Squaliformes, Torpediniformes, Elopiformes, Anguilliformes,
Clupeiformes, Aulopiformes Gadiformes Ophidiiformes, Batracoidiformes,
Lophiiformes, Cyprinodontiformes, Atheriniformes, Bercyciformes, Pegasiformes,
Syngnathiformes, Scorpaeniformes, Perciformes and Pleuronectiformes.
Ornamental Fishes : About 100 species (Murthy, 1969) have been recorded. The
dominant genera were Chaetodon, amphiprion, Abudefduf, Holocentrum, Upeneus
Parupeneus, Pomacanthodes, Acanthurus and Lactoria.
Crafts and gears : Fishing is carried out in the Palk Bay and the Gulf of Mannar
almost through out the day. The various gears operating in the Palk Bay and the Gulf
of Mannar are listed in Table 3.26. Primarily, various types of gill nets and seine nets
are used for pelagic fishing, while trawlers are used for harvesting demersal fishes.
Thangal (stay put) fishing which lasts for 5 to 7 days is also being practised by the
fishermen of Mandapam and Pamban island. Catamarans, dug-out canoes, plank
built Tuticorin type of thony/vallam, stitched masula boats are the traditional crafts in
use. The Tuticorin type of boats are operated either undersail or with inbuilt diesel
engine or in combination. Often catamarans and canoes too are used with outboard
engines.
The changing trend in fishing gears and crafts in this region is remarkable.
In early fifties, while 55% of the catch was made by boat seines operated from
catamarans, 34% came in gill nets operated from Tuticorin type of traditional crafts.
In late fifties, nylon nets were introduced and the harvest increased by 30%. Post
1970 period marked a revolution in fishing with the introduction of mechanised
trawlers and emergence of prawn fishery and an increase of over 40% in the total
fish catch. During 1980's in Tuticorin around 20,000 tonnes of fishes were landed by
trawlers and 10,000 tonnes by traditional fishing units.

Fishing Limits : Mechanised trawl fishing is being conducted usually upto 50 m (20
fathom) depth, while during November - February the fishermen go upto 180 metres
(100 fathom) for harvesting deep sea prawns. For collection of gorgonids, trawl nets
are operated beyond 50 metres depth. Non-mechanised units usually operate within
a depth of 36 metres (20 fathom).
Fishing in Mandapam and Rameswaram : Fishing units in the Palk Bay and the
Gulf of Mannar operate from Rameswaram. During the south-west monsoon period
(June - September), as the Gulf of Mannar side gets rough, fishing is carried out
mostly in the Palk Bay. During north-east monsoon (October - February), the fishing
shifts to the Gulf of Mannar which becomes calmer than the Palk Bay. The trawl
landings are concentrated at Mandapam, Pamban and Rameswaram. The most
important catch in the Mandapam area is silver bellies (48%), rays, croakers,
clupeids, goatfishes, perches, catfishes, lizardfishes and carangids. At Rameswaram
also, silver bellies dominate (51%), followed by rays (13%), croakers (9.5%) and
penaeid shrimps (9.4%), goatfishes, carangids, catfishes, flat fishes, clupeids,
cephalopods and crabs. Mackerel and carangids dominate the catch by the
indigenous gears. Anchovies and seerfishes also support a seasonal fishery. During
the lean inshore fishing season the fishermen of this area resort to 'Thangal fishing'.
Fish Production : The marine fish landings in the Gulf of Mannar can broadly be
classified into four groups, viz. pelagic, demersal, crustaceans and molluscs. During
1992 - 1996, the production has increased gradually from 55,325 tonnes in 1992 to
1,02,897 tonnes in 1996 (Table 3.27). In general, contribution of pelagic varieties is
maximum (54%) followed by demersal (35%), crustaceans (6%) and molluscs (5%).
While the harvest in the Gulf of Mannar is 20% of the total production in
Tamilnadu, it is estimated that exploitation in this area is 800 tonnes in excess of
sustainable yield, and the production rate is 14 tonnes km-2.
The major varieties contributing to fish production in this area are sardines,
carangids, silver bellies, perches, rays, penaeid prawns and cephalopods (Table
3.28). Higher salinity conditions and the temperate range 27.8-29.4OC favor the
Sardinella fishery at Tuticorin, Gulf of Mannar (Nalluchinnappan, et. al., 1982). Water
temperature and salinity appeared to influence the distribution of major finfishes
compared to dissolved oxygen. Groups such as threadfin breams were found

preferring cooler waters of wadge Bank area, while Barracudas appear to occupy
warmer waters of Gulf of Mannar (Balachandran, Agadi, 1996). While other sardines
dominated the catch in all the years between 1992 and 1996, the subdominant
varieties were cephalopods in 1992 and silver bellief during 1993 to 1996. Sardines
and Cephalopods are usually harvested by different gears in pelagic region.
However, the demersal varieties like silver bellies, penaeid prawns, rays, thryssa,
corakers etc. are primarily exploited by trawlers (Table 3.29). The catch through
trawlers further indicates that certain varieties like silver bellies, rays, croakers,
crabs, sardines, goat fishes and catfishes prefer the northern side of the Gulf of
Mannar, that is, Pamban and Rameswaram; while thryssa, carangids, stolephorus
and seer fishes are predominantly caught in the southern side, that is, Tuticorin
(Table 3.30).
The oil sardine, Sardinella longiceps fishery in the canal zone is a new
event. Even a few years ago this variety was rarely found in this area. During 1996
its catch was 1419 tonnnes. In the area adjoining Pamban island, its eggs and larvae
have been observed, indicating that the fish stock has become localised and breeds
in this area. Another important change is the unusual increase in mackerel
Rastrelliger kanagurta harvest. In 1992 the mackeral fishery was only 213 tonnes
and in 1996 it was 3711 tonnes. Sand lobster Thenus orientalis fishery of Tuticorin is
another newly emerging minor fishery.
Penaeid and Non-Penaeid shrimps: 41 species were reported
–
and the dominant genera were Penaeus, Metapenaeus,
Parapenaeopsis and Acetes. (CMFRI, 1998).
Lobster : 7 species namely Panulirus homarus, P. ornatus,
–
P.versicolor, P. longipes P. polyphagus, Puerulus sewelli and
Thenus orientialis were recorded (George, 1973).
Crabs : 210 species were observed (CMFRI, 1969 and 1998).
–
The dominant genera were Dromia, Cryptodromia, Rania,
Dorippe, Calappa, Scylla, Portuneus, Charybdis, Thalamita,
Demania, Leptodius, Atergatis, Phymodius and Doclea.
The green tiger prawns Penaeus semisulcatus, contributes to over 50% of the
total prawns catch landed along the Palk Bay coast. Intense fishing for juvenile

prawns, which inhabit the seagrass ecosystem near the shore, is taking place all along
the coast. The results of a survey carried out on this exploitation pattern are reported.
The prawn catch, the bulk of which is composed of juvenile P. seisulcatus, is found to
vary from 2 kg to 10 kg per unit per day. The size of the exploited P. semisulcatus
ranges from 31 mm to 100 mm total length with the dominant size group at 45-70 mm.
(Rao, 1988).
At coastal villages 16 potential landing centres were identified, 12 in Gulf of
Mannar region and 4 in the Palk Bay region and there came to know that the
Chicoreus ramosus and Pleuroploca trapezium fishery is mainly associated with
lobster fishery. The export value of the meat of these 2 gastropods has attracted the
attention of the fisher folk and it has emerged as an additional source of income for
them. In addition to the fishermen involved in fishing these gastropods, there are about
60 other persons engaged in the gastropod meat trade (Spec. Pub. Phukat Mar. Biol.
Cent. 1994). The seasonal prawn fishery (mainly of Penacus indicus) of Periathalai, a
fishing village on the south-east coast of Tamilnadu, lasts for a period of three to four
months in a year. But it is found that there is a gradual decrease in the female
population of this species (Rajamani, Manickaraja, 1990)
Non-conventional fishery : The Gulf of Mannar and the Palk Bay support select non-
conventional fishery resources. A historical pearl fishery exists here and the pearl oysters are
the property of the Tamilnadu Government. The areas where pearl oysters are found from
near shore region to the canal zone are shown in Fig. 3.11 and Table 3.31. The pearl oysters
settle and grow on hard rocky substrata called 'Paars' found abundantly from Pamban in the
north to Manapad in the south over a stretch of 160 km where 83 well known 'Paars' exist.
The beautiful natural pearls produced by these oysters are of high economic importance. The
Tamilnadu Pearl and Chank Fisheries Rules, 1978 under the Indian Fisheries Act 1897,
prohibit harvesting of pearl oysters and chanks in specified areas except with a licence
granted under the rules.
The natural production a pearl oysters in the pearls banks of the Gulf of
Mannar is Characterised by very wide fluctuations. Therefore, ability of producing pearl
oyster seed through hatcheries is of great importance for the development of pearl
culture industry in India. The barnacle Balanus amphitrite variegates was the major
fouling organism and Polychaete Polydora ciliata and the sponge (Clions vastifica)

were the main boring organisms responsible for heavy loading on the pearl systems.
(Symposium on coastal aquaculture, 1983).
In the vicinity of the pearl culture farm located off Veppalodai in the Gulf of
Mannar, the salinity remains high during the period of the south-west monsoon and
low during the north-east monsoon. There was not much variation in pH values and
dissolved oxygen content. The water was studied during the most part of the year, with
higher dissolved oxygen content. (Symposium on coastal aquaculture, 1983).
The specific fishing of sea horse (Hippocampus kuda) commenced in the
year 1992. The fisher folk of both the Palk Bay and the Gulf of Mannar consider this
specific fishing as a boon. The records of Marine Products Exports Development
Authority (MPEDA) show export of sea horse to the tune of 6 tonnes in 1991-92
followed by a decline to 2 tonnes in 1992-93, thus indirectly indicating a decrease in
sea horse population (Anonymous 1998).
Other non-conventional fisheries practised are for seaweeds, ornamental
shells, gorgonids and holothurians. The export data of MPEDA on sea fans and sea
ferns clearly shows a declining trend of 25 tonnes during
1975-79, 11 tonnes during 1980-84, one ton in 1990-91 and nil in 1992-93
(Anonymous, 1993). Similarly sea cucumbers are also indiscriminately fished in the
Gulf of Mannar and the Palk Bay. According to MPEDA records the export trend of
holothurians has started showing declining trend from 40 to 38 and finally 24 tonnes
in 1990-91, 1991-92 and 1992-93 respectively. One species of Holothuria (Metriatyla
scaber) is exclusively used in Gulf of Mannar and Palk Bay for the preparation of
beche-de-mer (James, 1987). The use of metal scrapers and other implements on
the sea grass beds to drag out the sea cucumbers are powerful enough to damage
the niche (James, 1989).
Breeding ground : There is not specific locality identifiable as breeding ground for
fishes. The fishes breed throughout the Palk Bay and the Gulf of Mannar and almost
through out the year. Fish eggs have been observed in the Gulf of Mannar
throughout the year with a peak in March and minor peaks in May, September and
November. In the Palk Bay also maximum number of fish eggs were collected in
March. The eggs were identified as belonging to clupeoids, carangids, Cynoglossus
and muraenids. There exists a minor fishery for juvenile fishes in the Pamban island

and in Theedai area during January-March, in which mostly baby sardines are
caught by torch (Choondu) fishing during night hours. At Kunthukal Point (Pamban)
very good quantities of juvenil milk fish (Chanos chanos) are caught during April-
June and September for use as seed stock for fish farming in various parts of
Tamilnadu and Kerala.
Spawning takes place in areas between 20m and 60 m depth in the northern
Gulf of Mannar. The spent adults migrate to the central Gulf of Mannar coast by
November – December. Spawning takes place around the full moon period.

The fry and fingerlings of the Indian sand whiting, Sillago sihama (Forskal),
which can serve as seed, have been found to occur in the coastal waters of the Palk
Bay throughout the year with at least three months of peak abundances in January,
May and October. The overall abundance was highest during full moon period, while a
direct relationship of the abundance of the fry and fingerlings could be noticed with the
increase in temperature and dissolved oxygen content (James, 1984).
A potential ground for milkfish (Chanos chanos) seed collection has been
located at Manoli Island in the Gulf of Mannar, where eggs and fingerlings of the
species congregate in large numbers in the tidal pools under the dense shades of the
mangrove bushes in April-May (Dorairaj et al., 1984). Juveniles of Penaeus
semisulcatus are found in large concentrations in the shallow inshore sea, between
Pattannamarudar and Tuticorin along the Tinnerelly coast in Tamilnadu and they are
fished throughout the year by an indigenous gear known as ‘Ola Valai’ operated in the
waters within 2 m depth. (Manisseri, 1982).
Turtles : Marine turtles are mainly omnivorous and often consume algae. For the purpose of
respiration they periodically surface like the marine mammals. The turtles migrate to the
shore for egg laying and prefer to come to the same site where they themselves once had
hatched out. Their nesting migration is during September - January. Five species of marine
turtles were recorded in the Gulf of Mannar and little is known about their distribution under
water. There are Chelonia mydas (green turtle), Hepidochelys olivacea (olive ridley), Caretta
caretta (loggerheads turtle), Eretmochelys imbricata (Hawk bill turtle), Dermochelys
coriacea (leather bask turtle). All are endangered species as per Wildlife (Protection) Act,
1972. A soft shelled turtle P. bibroni from Palk Bay can tolerate the marine environment, as
against the belief that it is purely a freshwater form (Nair and Badrudeen, 1975). Prior to
about 40 years, turtles used to lay eggs in the sandy beaches throughout the Gulf of Mannar
coast, both in the main lands and also in the islands including Sri Lanka. However, due to
increased human activity, presently they avoid Indian mainland coast but they do continue to
visit the Sri Lankan coast and the islands. Though their number is low in the Gulf of Mannar,
all the 5 species still lay eggs in these islands. Presently, capturing turtles is prohibited.
Mammals : 11 species have been recorded (Jamer and Lal Mohan, 1987, CMFRI, 1998)
including 6 species of whales, 4 species of dolphins and 1 species of dugong. All are
endangered species (Wildlife Protection Act, 1972). The cetacea (whales and dolphins) and
sirenia (sea cow) represent the main groups of marine mammals in the Gulf of Mannar.

Marine mammals have a layer of dermal fat or blubber. This acts as a stored reserve food for
future use in case of deficiency of food. The sirenia (sea cow) graze with their well developed
lips, in consequence, their teeth are little used and are greatly reduced in size. In cetacea,
whales and dolphins are mostly carnivorous and feed on crustaceans, squids, and fishes. In
sirenia, sea cow is herbivorous and feeds mainly on sea grasses.
A total of 187 species of shore birds including wadors, terns and gulls were
recorded in the Gulf of Mannar, of which 84 were of aquatic species and the remaining
terrestrial. The uncommon waders to India such as knot Calidris canuta, eastern knot
C. tenuirostris, Numenius arquata, whimbrel N. phaeophus and bar-tailed gotuit
Limosa lapponica were recorded as regular winter visitors to this area (Balachandran,
1995).
Dolphins and Whales : The dolphins found in the Gulf of Mannar and the Palk Bay
are oceanic and roam about in the area. It is most likely that only the frail and the
infirm whales move towards this area as known from standings of whales. So far no
mass standing of whales has been observed in the canal area. A male sperm whale P.
macrocephalus Linnaeus is rarely found on the southern side of Krusadai Island (Gulf
of Mannar), (James and Soundararajan, 1979). The dolphins Stenella longirostris and
Tursiops truncatus are often caught in various nets and the ones thus caught and
injured (probably) are clandestinely butchered for food. However, capture or harming
of the sea mammals is prohibited by law.
Sea Cow : Unlike dolphins and whales, sea cow (Dugong dugon) inhabits
the Palk Bay and the Gulf of Mannar preferably within 10 m depth limit not far from
the shore (1-3 km). Usually sea cows move in groups of 5-7 among the seagrass
Cymodocea, which is their chief diet. Their habitat extends from Adiramapattinam in
the Palk Bay to Taliyari island in the Gulf of Mannar (Fig. 3.13). The dugong which
grows to over 300 kg measuring 1-1.5 m in length, is harmless and sluggish in
nature. Its gestation period lasts for 13-14 months and gives birth to a single calf at a
time. Though young male adults compete among themselves for female, once they
have paired, they remain paired for the whole life. Their attachment to the partner
and calf is such that if one of the partners or calf gets caught the rest also shall
follow; thus becoming easy victims. They have no natural enemies except the
civilised man. The exact number of sea cows living in the Gulf of Mannar & the Palk
Bay is not known. Due to uncontrolled fishing carried out till recently and also due to

reduction in their grazing area and Cymodocea, their numbers have gone down
drastically. During 1980's, about 200 sea cows were killed per year. Now they are
protected by the Wildlife (Protection) Act, and are under threatened status.
Occasionally, marine mammals and turtles have been observed to get washed
ashore, and on examination it is found that the death was often due to propeller
cutus or eating of floatsam.
Marine Macroflora : Seaweeds or marine algae are primitive plants without any
root, stem and leaves. They grow in the intertidal and subtidal areas of the sea and
flourish wherever rocky, coral or any other suitable substrates are available for their
attachment. Based on the type of pigments, external and internal structures,
seaweeds, are divided into green, brown, red and blue-green algae. Seaweeds
constitute one of the commercially important marine living and renewable resources.
They contain more than 60 trace elements, minerals, protein, iodine, bromine,
vitamin and many bioactive substances.
Four seaweeds that are commercially collected along the coast of the Gulf
of Mannar are – Gracilaria edulis, Gelidiella acerosa, Sargassum wrightii and
Turbinaria sp. and these are one of the main sources of income in the concerned
villages. In the Hindu villages these also give the women one of their few fast
income. But now there is lack of sufficient quality and quantity of these sea weeds
(Uusitalo, 1987).
The 6 genera and 9 species of seagrasses of the marine flowering plants
recorded from the Gulf of Mannar are : Halodule uninervis, Cymodocea serrulata, C.
rotundata, Syringodium isoetifolium, Enhalus acoroides, Thalassia hemprichii,
Halophila ovalis, H. ovata and H. Stipulacea (Mahalingam and Gopinath, 1987).
Sea grasses are also marine plants belonging to two monocotyledonous
families, viz. Hydrocharitaceae and potamogetonaceae. These are the only
submerged marine angiosperms to have successfully adapted and survived in the
saline environment. Of the 52 species of seagrasses available in both tropical and
temperate waters around the world, 13 species are recorded in the Gulf of Mannar
Biosphere Reserve areas. The distribution of seagrass areas around the islands of
Gulf of Mannar is shown in Fig. 3.14.

Seagrass beds are highly productive and act as breeding and nursery
ground for many epiphytic fauna and feeding ground for sea cow (Dugong dugong).
Seagrass roots bind sediments and prevent erosion. Of the 52 species of
seagrasses recorded worldwide, 12 species were recorded in Gulf of Mannar
(Ramamurthy et al, 1992). The dominant genera are Cymodocea, Thalassia,
Halophila, Halodule, Enhalus and Syringodium. The details of distribution pattern of
seagrass in the islands of Gulf of Mannar is depicted in Table 3.32.
Importance of Seaweeds and Sea Grasses
Seaweeds are the only source for the production of agar,
–
carageenan and sodium alginate. While agar is manufactured
from red algae like Gelidiella, Gelidium, and Gracilaria,
carageenan is prepared from other varieties of red algae like
Fucheums, Chondrus, Hypnea and Cigartina. The sodium alginate
is obtained from brown algae such as Sargassum, turbinaria,
Laminaria, Undaria, Macrocystis and Ascophyllus.
The brown algae Dictyota bartayresiana collected in the Gulf of
–
Mannar of the Indian Ocean yielded diterpenes consisting of one
known dolastane, five known dolabellanes and five new
compounds (Rao et al., 1994)
Seaweeds act as a breeding and nursery ground from some
–
species of fishes and invertebrates.
Brown seaweeds are used for manuring, as feeds, fodder for
–
cattle, sheep, goats and pigs, and also for extraction of potash
and iodine.
Although a few animals may feed directly on the seagrass, the
–
major food chains are based on seagrass detritus and its resident
microbes.
Seagrass is the main feed for the sea cow Dugong dugon
–
(endangered marine mammal). The organic matter in the detritus
and in decaying roots initiates sulfate reduction and maintains an
active sulfur cycle.

A total of 42 species of green algae, 31 species of brown algae,
69 species of red algae, 5 species of blue-green algae and 13 species of grasses
were recorded in the Palk Bay and the Gulf of Mannar (CSMCRI, 1978,
Parthasarthy, et al., 1991). The area covered from Athankarai to Rameswaram (45
km coastline) in the Palk Bay and from Mandapam to Welamidalam (413 km
coastline) including 21 islands of the Gulf of Mannar possess higher density of algal
distribution. Standing crop of the macroalgae from the total area of 17,125 ha (above
said area) is 22,044 tonnes (wet wt.), consisting of 1,709 tonnes of agarophyses,
10,266 tonnes of alginophyses and 10,069 tonnes of other seaweeds. The
commercially important species, viz., Gelidiella acerosa Gracillaria sp., Hypnea sp.,
Sargassum Turbinaria
sp. and sp. contribute
74, 974, 798, 9381 and 714 tonnes respectively (Kalimuthu et al. 1990).
Maximum Diversity Index Values for seagrasses in 21 islands of Gulf of
Mannar are shown in Table 3.33 and Fig. 3.15. The values ranged from 2.07 to
2.48. Thus, variation in diversity of seagrass at different islands is less.
Mangrove : Mangroves are salt tolerant forest eco-systems found in select islands
and also at certain intertidal regions. These are exposed at low tides and partially
submerged during the high tides. The plants comprise the true mangroves as well as
other flora which are associated with the mangroves to form the 'Mangrove
community'. The significance of mangroves is as follows :
Mangroves help to prevent coastal erosion and built land from the
–
sea.
Mangrove vegetations help to provide food and shelter during part
–
or all of the cycle of many marine species and act as a nursery
ground for many marine organisms.
Mangroves help to stabilize the coastal areas by reducing wind
–
damage and wave energy during storms.
Maximum Diversity Index values of mangroves in 21 islands of Gulf of
Mannar are shown in Table 3.34 and Fig. 3.16. The locations of mangroves in Gulf
of Mannar and Palk Bay are shown in Fig. 3.17. Relatively good diversity (>2) was
observed at 9 islands, no diversity at 2 islands and moderate diversity at 10 islands.

The list of mangrove species recorded in Palk Bay and Gulf of Mannar is given in
Table 3.35.
It is believed that mangroves along the main land coast and river mouths of
the canal zone have been reduced or replaced by habitation and saltpans.
Mangroves and the associated vegetations in the islands are said to be under
constant pressure. Although detailed studies have not been carried out, the islands
like Krusadai, Shingle, New Manauli and Poomarichan islands possess patches of
mangroves (Stoddart & Fosberg, 1972). The genera Avicennia and Rhizophora are
predominant in these islands. The Pamban Islands also have dense mangrove forest
cover with several species, which are degraded due to human activities like grazing
by domestic cattle & firewood exploitation by rural poor people.
The coastal mangrove has little value & occupy very narrow strip of few
meter widths along the coast or lagoon. The mangrove formation around
Rameshwaram is discontinuous & about 100 years old (Venkatesan, 1986). From
the seacoast of Rameshwaram island, Rhizophora apiculata, Ceriops tagal,
Aricennia alba, Bruguiera, Gymnorhiza are identified. Stoddart & Fosberg (1972)
have reported minor patch of mangroves near Rameshwaram. The species of
mangroves found in the estuarine coast of Palk Bay and deltaic ecosystem of Gulf of
Mannar are given in Table 3.35.
Around 9 species of mangroves (Krishnamurthy, 1987) and 7 associated
species were found in Gulf of Mannar. The dominant genera were Avicennia,
Rhizophora, Bruguiera, Lumnizera, Ceriops and Pemphis. The genera Avicennia and
Rhizophora are found to be dominant in Krusadai, Poomarichan, Pullivasal, Musal,
Anaiparand and Upputhanni islands. Manoli and Manoliputti show a high species
diversity of mangroves (Avicennia, Rhizophora, Bruguiera, Lumnitzera and Ceriops).
Pemphis acidula is found in all the islands. The details of distribution pattern of
mangrove vegetation in the islands of Gulf of Mannar is given in Table 3.36.
Out of 3140 km2 area of mangroves in India, the contribution of Tamilnadu is
only 100 km2. Major regions of mangrove formations in the state are Killai, Muthupet
and Chatrom (Puthupatinam and Talanayer 1993, Anonymous 1997). In general,
mangroves in coastal regions along the study area as also in the 21 islands in the
Gulf of Mannar are negligible in India is total.

Biodiversity : The GOMMBRE is endowed with various ecosystems, viz. coral reef,
sea grass and mangrove. In these ecosystems different flora and fauna with varying
ecological habitats are represented in great numbers. In order to indicate the rich
biodiversity, pluralism and endemism the important groups of biota and species
composition have been studied by different agencies. A review by CMFRI, Kochi on
select literature published during 1903-1986 towards flora and fauna in GOMMBRE
indicates that over 3268 varieties of organisms under different groups were present
in this area (Table 3.6). However, the booklet published by Tamilnadu Forest
Department, Ramanathapuram (Upreti and Shanmugaraj 1997) mentioned that
GOMMBRE possesse 3600 species. Further, studies carried out by Zoological
Survey of India (Anonymous 1998) concluded that presently there are 1060 species
in GOMMBRE (Table 3.6). It is of interest to note that the only species of marine
insects present in the region is Halobates herdmani which is also endemic in the Gulf
of Mannar. Wide fluctuation of diversity of biota as reported by different agencies is
attributed to following factors.
The papers reviewed by CMFRI cover the species recorded in the
–
area during long wide period of time, while the species enlisted by
ZSI is based on 5 surveys undertaken during 1993-97 in the
GOMMBRE. All the species recorded by CMFRI may not be
available in present years due to ecological changes over a
course of time.
Certain groups of species, viz. mangroves, phytoplankton,
–
chaetognatha, etc. were not included in the list prepared by
CMFRI, while the species of major groups like mangroves, sea
grass, marine algae, zooplankton, avifauna etc. were not
encountered in the list of ZSI.
While referring occurrence of 3600 species of plants and animals
–
in the GOMMBRE, the report (Anonymous 1998) from M.S.
Swaminathan Foundation documented availability of 168 types of
birds in its 21 islands. The number is more than double than that
(61) recorded by CMFRI. It may be mentioned that the number of
species varied widely during different seasons in the same year.

Literature on number of species and diversity index reveals that, in
general, the biodiversity of this region is fairly high. This is supported by
comparatively higher diversity indices of zooplankton in the Gulf of Mannar and the
Palk Bay from the records at different coastal regions of India (Table 3.13).
However, comparative account of primary productivity values at different seas (Table
3.37) support that the productivity in the Gulf of Mannar is substantially low from
those of other reef ecosystems, viz. Minicoy, Andaman, Kavaratti etc. Maximum
Diversity Index values of corals, mangroves and seagrass are shown in Fig. 3.18
which show that most of the islands have good biodiversity of these plants and
animals.
3.3 Biodiversity of Islands in Study Region
The 21 islands of Gulf of Mannar are divided into four groups namely
Mandapam, Keezhakarai, Vembar and Tuticorin due to the proximity of islands to
these locations.
3.3.1 Mandapam Group
There are seven islands present in Mandapam group covering an area 262.3
ha. It is nearest group of island to the proposed project site.
Seven islands present in this region are biologically very rich. Krusadai island
is the “Biologist’s Paradise”, as it holds maximum genetic diversity. Patch reefs are
found on the southern and northern side of the islands. Fringing reefs occur along the
southern side at a distance of about 1 to 5 km. Dugong foraging grounds are
extensive. 35 species of corals, 12 species of seagrasses and
9 species of mangroves are found in this group.
Coral reefs were surveyed during low tide times. They were observed at
different zones in exposed areas. Some of the islands were small with an area less
than 5 to 7 km2. Around Muyal theevu (Hare Island) coral reefs were noticed along the
entire southern portion as a stretch and into the sea for about 2 km. On the northeast it
extended to a distance of about 1 km in width. Manoli and Manoliputti islands have
coral reefs occupying an area of about 8 km2, in the shallow region. Pullivasal and
Shingle region could be seen clearly during low tide. Krusadai Island had coral reefs
on the eastern side, which was about 200 meters wide and ran to about 1-km length

on the southwest direction. The common coral fauna found around the Mandapam
group of island is given in Table 3.38.
Corals are mostly found upto 5m depths. More number of live coral points
exists around Manoli and Manoliputti islands. Coral reef area around the islands is
about 41 sq.km. Seagrass covers an area of about 23 sq.km around the islands.
Fringing reefs were found from 100 to 500 meters away from the shore
around the islands. They were not continuous but were broken here and there. They
occurred mostly abound all the islands. Underwater survey of coral reefs yielded
information on the various species of corals found surrounding the Mandapam group
of islands in the Gulf of Mannar and are given in Table 3.38. There was a rich variety
of coral fauna. There were more than 31 species of
7 genera of coral fauna. Of this 7 species belonging to 7 genera were hermatypic.
The most commonly occurring genera of corals were Acropora, Montipora
and Porites. Coral associated animals included a variety of fishes. Other associated
fauna included sea anemones, star fishes, sea urchins, pipe fishes, sea fans,
holothurians, shell fishes such as lobsters, gastropod molluscs, and fin fishes such as
Epinephelus (grouper), Siganus (rabbit fish), Lethrinus (pig fish), Caranx (horse
mackerel), and Serranus. Various coral associated fauna, their shelter and food items
are given in Table 3.39.
Seaweeds occur in the intertidal, shallow and deep water of the sea upto 180
m depth and also in estuaries and backwater. They grow on dead corals, rocks,
stones, pebbles and other substrate and as epiphyte on sea grasses. Several species
of green, brown and red algae with luxuriant growth are observed in this area.
Total 180 species of seaweeds are growing in Mandapam region, of which
about 40 species are economically important. These species are Enteromorpha, Ulva,
Caulerpa, Codium (Green algae), Colpomenia, Hydroclathrus, Cystoseira,
Hormophysa, Sargassum, Turbinaria (Brown algae), Asparagopsis, Gelidiella,
Gracilaria, Sarconema, Hypnea, Acanthophora and Laurencia (Red algae). The
biomass of economically important seaweed of Gulf of Mannar is estimated as 8445
tonnes (Wet weight).
The giant sea anemone, Stoichaetis giganteum (Forsk), was found to grow
both on sandy areas as well as on rocky bottom. Often many clown fishes such as,

Amphiprion spp. and damselfishes such as, Dascyllus trimaculatus (Ruppells) were
found swimming over the anemones. Sacred chanks (Xancus pyrum Linnaeus) were
found in shoreward areas, shallow waters and also at greater depths of 10 meters and
above. Other invertebrates are found Clypeaster humilis, Salmacis bicolor, and Murex
tribulus. Sea cucumber (Holothuria atra) and (Holothuria scabra) were also found.
Dense growth of Echinolampus spp., Clypeaster humilis, and some Astropecten spp.,
was also observed. Alcyonarians, Pennatulids, and filamentous green algae were also
found at deeper areas. Lobsters, sea fans, sea horses, echinoderms, ornamental
shells like cowries and tiger shells and a number of species of crabs including edible
and non-edible ones were also found.
The green turtle Chelonia mydas (Linnaeus) is found in Mandapam region.
The major food items observed in their stomachs are sea grasses and sea weed (Pillai
and Thiagarajan, 1979).
3.3.1.1 Shingle Island
Coral distribution
Fringing reefs on the eastern, northern and western sides occur at distance of
300 m from the shore. Coral reef covers an area of about 2 sq.km. Live coral coverage
is about 46%. 15 species have been recorded in the current study.
The species recorded are Acropora hyacinthus, Montipora digitata, M.
divaricata, M.foliosa, Echinopora lamellosa, favia pallida, F.valenciennesi, Favites
abdita, Goniastrea pectinata, G.retiformis, Leptastrea transversa, Platygyra lamellina,
Galaxea fascicularis, Pocillopora damicronis and Porties solida.
Seagrass distribution
Seagrass is distributed all around the island covering an area of about 0.21
sq.km. 11 species have been recorded. They are Cymodocea rotundata,
C. serrulata, Syringodium isoetifolium, Halodule uninervis, Halophila ovalis, Halophila
ovata, Thalassia hemprichii, Halophila stipulacea, Halophila decipiens, Halophila
beccarii and Halodule pinifolia.
Mangrove distribution
The swamp in the island possesses mangroves. Six species of mangroves
and 5 associated species are recorded. The recorded species are Avicennia marina,
Rhzophora mucronata, Ceripos tagal, Bruguiera cylindrica, Lumnitzers racemosa,

Pemphis acidula, Salvadora persica, Pandanus sp, Sesuvium sp, Scaevola sp and
Thespesia populnea.
3.3.1.2 Krusadai island
Krusadai Island known for its rich biodiversity is referred to as the “Paradise of
biologists”. The island is about 3.5 km from Mandapam and covers an area of about
66 ha. The southeast part of the island is sandy and the northern part muddy with
marshy vegetation.
The Krusadai group of islands, serve as windbreaks and help to prevent soil
erosion. The Krusadai island, is 125 acres rectangular and somewhat (inverted) boat-
shaped, it is separated by 250 m of sea from the nearest point of Rameshwaram
Island. For protection of Krusadai Island, the proper mangrove vegetation and its
proper management is necessary. (Lakshmanan, K.K.; Rajeswari, M.; Jayalakshmi,
R., 1984).
Coral distribution
Continuous fringing reefs on the southern side extends upto 500 m. Coral
reefs cover an area of about 1.5 sq. km. Live coral coverage is about 33%. 19 species
have been recorded in the current study.
The recorded species are Acropora humilis, A. hyacinthus, Montipora digitata,
M. divaricata, M. foliosa, M. verrilli, Echinopora lamellose, Favia pallida, F.
valenciennesi, Favites abdita, Goniastea pectinata, G. retiformis, Leptastrea
transversa, Platygyra lamellina, Galaxea fascicularis, Pocillopora domicornis,
Goniopora planulata, Porites lichen, Coscinaria monile and Psammocora contigua.
Seagrass distribution
Seagrass is distributed all around the island covering an area of about 3 sq.
km. About 12 species have been recorded and the species are Cymodocea rotundata,
C. serrulata, Syringodium isoetifolium, Halodule uninervis acidula, Halophola ovalis,
Halophila ovata, Thalassia hemprichii, Enhalus acoroides, Halophila stipulaceae, H.
decipiens, H. beccarii and Halodule pinifolla.
Mangrove vegetation
Mangroves are located in the peripheral region along the northern side of the
island. Seven species of mangroves and 6 associated species are recorded. They are

Avicennia marina, Rhizophora mucronata, Ceripos tagal, Brugiera cylindrical, Pemphis
acidula, Exoecaria aggallocha, Aegiceras corniculatum, Salvadora persica, Pandanus
sp., Sesuvium sp., Scaevola sp, Suaeda sp. and Thespesia populnea.
3.3.1.3 Pullivasal and Poomarichan Island
Pullivasal island is located about 3 km east of Mandapam. It covers an area
of about 29 ha and the maximum elevation of the island is 3 m. The island is
adjacent to Krusadai Island and accessible from Poomarichan island by crossing a
shallow stretch of water. Thickly wooded trees are found in the island.
Poomarichan Island is located about 3 km east of Mandapam and covers an
area of about 27 ha and the maximum elevation of the island is 1.5 m. The island is
‘U’ shaped and has marshy soil with good vegetative cover.
Coral Distribution
Fringing reefs occur at a distance of 400 m in the southern side and patch
reef occurs beyond the muddy area in the northern side of Pullivasal Island. Coral
patches close to the island are exposed during low tide.
Coral reefs are found in the western and eastern side of the Poomarichan
Island at a distance of 150 m from the shore. On the southern side continuous reef
exists close to the shore.
Coral reefs cover an area of about 4 sq.km. Live coral coverage is about
14% (includes area around both the islands). Sixteen species of corals are recorded
around the Pullivasal island in the current study. The recorded species are Montipora
digitata, M. foliosa, Echinopora lamellosa, Favia pallida, Goniastrea, G. retiformis,
Leptastrea transversa, Pocillopora damicornis, Porites solida, P. lichen,
Psammocora contigua, Symphyllia radians, Acropora hyacinthus, A. humilis, A.
formosa and A. abdita.
Twelve species of corals are recorded around the Poomarichan island in the
current study. The species recorded are Acropora corvmbosa,
A. plantaginea, A. valenciennesi, Montipora digitata, M. divaricata, M. divaricata,
Favia pallida, F. valenciennesi, Favites abdita, Goniastrea pectinata,
G. retiformis, Pocillopora damicornis and Porites mannarensis.
Seagrass distribution

Seagrass is distributed all around both the islands and covers an area of
about 5 sq. km. Twelve species are recorded and the dominant species are
Cymodocea rotundata, C. serrulata, Syringodium isoetifolium, Halodule uninervis,
Halophila ovalis, Halophila ovata, Thalassia hemprichii, Enhalus acoroides,
Halophila stipulaceas, Halophila decipiens, Halophila beccarii and Halodule pinifolia.
Mangrove distribution
Dense mangrove vegetation observed along the periphery region of the both
islands. Seven species of mangroves and 5-associated sp. are recorded. They are
Avicennia marina, Rhizophora mucronata, R. apiculata, Lumnitzera racemosa,
Ceriops tagal, Bruguiera cylindrica, Pemphis acidula, Salvadora percisa, Pandanus
sp, Sesuvium sp, Scaevola sp and Tespesia populnea.
3.3.1.4 Manoli and Manoliputti Islands
Manoliputti island is located at about 5 km from Mandapam and covers an
area of about 2 ha. The maximum height of the island from sea level is about 2 m.
Manoli island is located about 5 km from Mandapam and covers an area of
about 26 ha. Manoli is separated from the nearby Manoliputti island by an extensive
mudflat, which gets exposed during low tide. The islands were formed of sandy clay
and dead coral pieces. The northern and southern beach ridges were found
separated by an area of Thespesia woodlands. Pools and open mudflats were found.
The maximum elevation of the island is 2 m.
Coral distribution
Massive corals are observed along the northern portion of the island. On the
southern side fringing reefs extend far outside upto a distance of 1.25 km from the
shore. Coral reefs cover an area of about 15 sq. km. Live coral coverage is about
25% (includes area around both the islands). Thirteen species of corals are recorded
around Manoliputti island and they are Montipora digitata, M. divaricata, M.foliosa,
Echinopora lamellosa, Favia pallida, Favities abdita, Goniastrea pectinata, G.
retiformis, Platygyra lamellina, Pocillopora damicornis, Porities lichen, P. lutea and P.
solida.
Twenty five species of corals are recorded around Manoli island and they
are Acropora corymbosa, A. humilis, A. millepora, A. nobilis, A. plantaginea, A.
valenciennesi, Montipora digitata, M. divaricata, M. foliosa, M. granulosa,

M. verrilli, Echinopora lamellosa, Favia pallida, Favites abdita, Favites pentagona,
Goniastrea pectinata, G. retiformis, Leptastrea transversa, Platygyra lamellina,
Pocillopora damicornis, P. verrucosa, Goniopora planulata, Porites lichen, P. lutea
and P. solida.
Seagrass distribution
Seagras are distributed all round both the islands. Twelve species of
seagrass are recorded. Seagrass beds cover an area of about 5 sq. km. The
recorded species are Cymodocea rotundata, Cymodocea serrulata, Syringodium
isoetifolium, Halodule uninervis, Halophila ovalis, Halophila ovata, Thalassia
hemprichii, Enhalus acoroides, Halophila stipulacea, Halophila decipiens, Halophila
beccarii and Halodule pinifolia.
Mangrove distribution
In Manoliputti very thick mangrove vegetations are found along the
periphery region of the channel and around the island. Six mangroves and
6 associated sp. are recorded and they are Avicennia marina, Rhizophora
mucronata, Ceriops tagal, Bruguiera cylindrica, Excoecaria agallocha, Pemphis
acidula, Salvadora persica, Pandanus sp, Sesuvium sp, Scaevola sp, Thespesia
populnea and Salicornia sp.
In Manoli island, mangrove vegetations show dense distribution along with
high species diversity. Eight mangroves and 6 associated as recorded are
Rhizophora apiculata, Avicennia marina, Rhizophora mucronata, Ceriops tagal,
Bruguiera cylindrica, Excoecaria algallocha, Pemphis acidula, Salvadora persica,
Pandamus sp., Sesuvium sp., Scaevola sp., Thespesia populnea and Salicornia sp.
3.3.1.5 Musal Island
Musal Island is the largest among the Mandapam Group in the Gulf of
Mannar. This island is located at about 7 km from Mandapam in the southwest
direction and covers an area of about 29 ha. The total surface area is about
1.3 sq. km. The length of the island is about four kilometers with a width of 250 to
1800 m at different places. The elevation is about 3.5 to 4 m. It is a fairly large island
characterized by thick cover of vegetation consisting of Acacia trees, coconut and
palmyra plantations.

Coral Distribution
Boulder reef patches occur in the southern side of the lagoon. Fringing reef
occurs at about 1.5 km on the southern side and runs continuously eastwards. It
however becomes discontinuous towards the north. Coral reefs cover an area of
about 18 sq. km. Live coral coverage is about 52%. Twenty nine species are
recorded in the current study.
The recorded species are Acropora corymbosa, A. formosa,
A. millepora, A. nobilis, A. plantaginea, A. Ualenciennesi, Montipora digitata,
Montipora divaricata, M. foliosa, M. verrilli, Echinopora lamellosa, Favia pallida,
Favites abdita, F. Pentagona, Goniastrea pectinata, G. retiformis, Leptastrea
transversa, Platygyra lamellina, Symphyllia nobilis, Galaxea fascicularis, Pocillopora
daicornis, Goniopora nigra, G. planulata, Porites lichen, P. mannarensis, P. lutea, P.
solida and Coscinarea monile.
Seagrass distribution
Seagrass are present all around the island covering an area of about 9.5 sq.
km. Twelve species of seagrass have been recorded as Cymodocea rotundata, C.
serrulata, Syringodium isoetifolium, Halodule uninervis, Halophila ovalis, Halophila
ovata, Thalassia hemprichii, Enhalus acoroides, Halophila stipulacea, Halophila
decipiens, Halophila beccarii and Halodule pinifolia.
Mangrove Distribution
Dense mangrove vegetation with high species diversity is found to occur is
this island. Six species of mangroves and 6 associated species are recorded. The
recorded species are Avicennia marina, Rhizophora mucronata, Lumnitzers
racemosa, Ceriops tagal, Bruguiera cylindrica, Pemphis acidula, Salvadora persica,
Pandanus sp., Sesuvium sp., Scaevola sp., Salicornia brachiata and Thespesia
populnea.
3.3.2 Marine Organisms Observed around the
Mandapam Group of Island
Phytoplankton distribution
Seventy eight species of phytoplankton are recorded in Gulf of Mannar. In the
Mandapam group, 59 species of Bacillariophyceae, 9 species of Dinophyceae, 4
species of Cyanophyceae and 2 species of Chlorophyceae totalling to 74 species of

phytoplankton were recorded. Maximum number of species was recorded in
Manoliputti, Poomarichan and Musal. The phytoplankton count varied from 3 – 872
nos/ml.
Zooplankton distribution
Sixtytwo species of zooplankton are recorded in Gulf of Mannar. In the
Mandapam group alone 46 species of Crustacea, 1 species of Granuloreticulosa, 1
species of Hydrozoa, 2 species of Polychaeta, 5 species of Polyhymenophora, 3
species of Sagittoidea and 2 species of Thaliacea totalling 60 species of zooplankton
were recorded. Maximum number of species was recorded around Musal and Shingle
islands. The density of zooplankton varied from 1000-9000 nos/cu.m.
Benthos distribution
In the current study (1998-99), 198 species of benthic organisms were
recorded in Gulf of Mannar. In the Mandapam group 11 species of Protozoa,
16 species of Porifera, 37 species of Cnidaria, 17 species of Annelida, 2 species of
Platyhelminthes, 9 species of Nematoda, 1 species of Echiura, 3 species of Sipuncula,
31 species of Mollusca, 41 species of Arthropoda, and 15 species of Echinodermata, 1
species of Hemichordata, totalling184 species of benthic organisms were recorded.
Musal island exhibited maximum species diversity.
Ornamental fishes distribution
A total of 128 species of ornamental fishes are recorded in Gulf of Mannar, of
which 91 species were recorded around the Mandapam group. The dominant species
were recorded in the families of Chaetodontidae, Pomacentridae, balistidae and
Apogonidae.
Capture fisheries
A total of 130 species of fishes were recorded in Gulf of Mannar. In the
Mandapam group 9 species of Chondrichthyes (Elasmobranchs), 66 species of
Actinopterygii (Teleostei), 12 species of Crustaceans and 5 species of Cephalopods,
totalling 92 species were recorded.
3.3.3 Trend of Fish Catch in Mandapam Region
Trap fishing was carried out in and around Mandapam group of islands
normally from January to March and September to December every year. About 500

to 600 traps were operated daily in the Gulf of Mannar along the coast of Mandapam,
Vedalai, Pullivasal and Pudumadam. Altogether 23 species of fishes belonging to 15
families were found to occur in the Mandapam area. A study of the percentage
composition of the different species in the total catches from the Gulf of Mannar
revealed that Lethrinus cirereus (emperor fish) formed 57%, the next important being
Callyodon ghobbon forming 26%. The species Lutjanus Johsuii (snapper) formed 5%
and Therapon puta formed 4%. Other fishes such as Psammoperca wigiensis,
Epinephelus tauvina, (grouper fish), Teuthis marmorata, Pelates quadrilineatus,
Plectorhynchus schotat (sweet lip fish), Parapenaeus indicus (Goat fish), Upeneoides
tragula, Halichaers spp., Chiloscyllium indicum, Plotosus spp., Gerres spp., and
Acanthurus spp., (surgeon fish) formed 8%. Underwater photographs of some of these
fishes were taken.
3.3.4 Keezhakarai Group
Keezhakarai group consists of seven islands located about 8 to 10 km from
the main land. Patch and fringing reefs occur along the northwestern and southern
side of the islands. Dugong foraging grounds are extensive around Valai and Appa
islands. Thirty one species of coral, 12 species of seagrass and 6 species of
mangroves are found in the Keezhakarai group of islands.
Field survey was carried out during Jan. 2000 in all the seven islands of
Keezhakaria Group for mapping the extent of coral distribution. Information on the
distribution of corals was collected using DGPS, scuba diving and skin diving. By
underwater survey, areas of abundance of corals were identified and observation
points fixed. At each point, percentage of live corals was determined visual
confirmation of coral reef areas. Corals are mostly found upto 5 m depth. Live corals
are found beyond 0.5 m depth. More number of live coral points exist around
Poovarasanpatti and Valimunai islands. Coral reef area around the islands is about 37
sq. km.
Field survey was carried out during Jan 2000 in all seven islands for mapping
the extent of seagrass. Information on the distribution of seagrass was collected using
DGPS, scuba diving and skin diving. GIS has facilitated overlay of depth contours on
seagrass areas. Seagrass covers an area of about
43.5 sq. km around this island.

3.3.4.1 Mulli Island
Mulli Island is located at about 10 km from Keezhakarai and covers an area
about 10 ha. It is a small sandy island with a vegetative cover consisting of bushes
and shrubs. The swampy regions are surrounded by muddy terrain.
Coral distribution
Boulder reef occurs in the northern side and fringing reef on the eastern side
of the island. Coral reef covers an area of about 7 sq. km. Live coral coverage is about
25%. 18 species have been recorded in the current study. The species recorded are
Acropora corymbosa, A. millepora, A. humilis,
A. hyacinthus, Coscinarea monile, Turbinaria peltata, Porites lutea, P. solida,
Goniastrea retiformis, G. pectinata, Favites abdita, Leptoria phrygia, Montipora foliosa,
M. spumosa, M. digitata, Echinopora lamellosa, Pavona varians and Pocillopora
damicornis.
Seagrass distribution
Seagrass beds occur all around the islands covering an area of about
2 sq. km. Eleven species of seagrass have been recorded and the recorded species
are Cymodocea rotundata, C. serrulata, Syringodium isoetifolium, Halodule uninervis,
Halophila ovalis, Halophila ovata, Thalassia hemprichii, Halophila stipulacea, Halophila
decipiens, Halophila beccarii and Halodule pinifolia.
Mangrove Distribution
Dense Distribution of Pemphis and other halophytic plants occur in the island.
Five species of mangroves and 5 associated species are Avicennia marina,
Rhizophora mucronata, Ceriops tagal, Bruguiera cylindrica, Pemphis acidula,
Salvadora persica, Sesuvium sp, Thespesia populnea, Suaeda sp. and Scaevola sp.
3.3.4.2 Valai and Talairi Islands
Valai is a small linear island parallel to the mainland covering an area of
about 10 ha. Talairi is an extensive elongated island with linear axis parallel to the
shore and covering an area of about 75 ha. The broadest portion of Talairi is on the
western tip and is densely covered with trees. A channel connects the islands, which
is submerged during high tide. The islands are located at a distance of about 9 km
from Keezhakarai.
Coral distribution

Boulder and fringing reefs occur along the northwestern and southern side of
the islands. Coral reef covers an area of about 14 sq. km. and the live coral coverage
is about 16% (includes area around both the islands).
In the current study 11 species (51 species – past data) of corals are
recorded around Valai island. The recorded species are Montipora digitata, M.foliosa,
Pocillopora damicornis, Porites solida, P. lutea, Goniastrea sp. Montipora digitata, M.
foliosa, Porites lutea, P. solida, Acropora corymbosa,
A. formosa, A. humilis, Goniastrea retiformis, G. pectinata and Favites abdita
Segrass distribution
Seagrasses occur all around the islands covering an area of about
8 sq. km. Eleven species of seagrass have been recorded. The recorded species are
Cymodocea rotundata, C. serrulata, Syringodium isoetifolium, Halodule uninervis,
Halophila ovalis, Halophila ovata, Thalassia hemprichii, Halophila stipulacea, Halophila
decipiens, Halophila beccarii and Halodule pinifolia.
Mangrove Distribution
Dense distribution of Pemphis and other halophytic plants occurs in the
island. Two species of mangroves and 5 associated species are recorded. The
recorded species are Avicennia marina, Pemphis acidula, Salvadora persica,
Sesuvium sp, Scaevola sp, Salicornia sp and Thespesia populnea.
3.3.4.3 Appa Island
Appa Island is located at about 8 km from Keezhakarai and covers an area of
about 28 ha. The southern island portion is highly elevated standing on fossilised coral
stones of large dimensions. The northern portion of the island has an elevation of 6 m
from the spring tide level.
Coral distribution
Coral reefs occur all around the island except for a small patch on the eastern
side covering an area of about 5 sq.kms. Live coral coverage is about 2%. In the
current study 10 species have been recorded and they are Montipora digitata,
Montipora foliosa, Porites lichen, P. lutea, P. solida, Coscinarea monile, Acropora
hyacinthus, Goniastrea retiformis, G. pectinata and Favites abdita.
Seagrass distribution

Seagrass beds are distributed all around the island covering an area of about
8 sq.km. Nine species of seagrass have been recorded and they are Cymodocea
serrulata, Syringodium isoetifolium, Halophila ovata, Thalassia hemprichii, Halophila
stipulacea, Halophila decipiens, Halophila beccarii and Halodule pinifolia.
Mangrove vegetation
Dense distribution of Pemphis and other halophytic plants occurs in the
island. One species of mangrove Pemphis acidula and 2 associated species
Salvadora persica and Sesuvium sp are recorded.
Poovarasanpatti island is completely submerged and gets exposed
occasionally during low tide. The island occurs between Appa and Valimunai islands
and is about 8 km from Keezhakarai. Valimunai is located at about 9 km from
Keezhakarai mainland and covers an area of about 7 ha. The island is characterized
by sandy shore and thick cover of Acacia trees and tall bushes.
Coral distribution
Coral reef occurs all around the island covering an area of about
6 sq. km. Live coral coverage is about 50% (including area around both the islands). In
the current study, 11 species were recorded around Poovarasanpatti island. The
recorded species are Goniastrea retiformis, Porites lutea, Acropora hyacinthus, A.
nobilis, Montipora spumosa, M. foliosa, M. digitata, Turbinaria peltata, Favia pallida,
Platygyra lamellina and Favites abdita.
In the current study, 12 species were recorded around the Valimunai island.
The species are Goniastrea retiformis, Porties mannarensis, Portites solida, Acropora
hyacinthus, A. humilis, Montipora spumosa, Turbinaria peltata, Favia pallida, Favia
favus, Echinopora lamellosa, Platygyra lamellina and Favites abdita.
Seagrass distribution
Seagrass beds occur all around the islands covering an area of about 11.5
sq. km. Nine species of seagrass are recorded and the recorded species are
Cymodocea serrulata, Syringodium isoetifolium, Halophila ovalis, Halophila ovata,
Thalassia hemprichii, Halophila stipulacea, Halophila decipiens, Halophila beccarii and
Halodule pinifolia.
Mangrove distribution

Dense distribution of Pempbis and other halophytic plants occurs in Valimunai
Island. One species of mangrove and 4 associated species are recorded. The
recorded species are Pemphis acidula, Salvadora persica, Sesuvium sp, Scaevola
and Thespesia populnea.
3.3.4.4 Anaipar Island
Anaipar is located at about 9 km from Keezhakarai and covers an area of
about 11 ha. The maximum elevation of the island is about 3 m.
Coral distribution
Coral reef occurs all around the island covering an area of about
5 sq. km. Live coral coverage is about 37%. Twety one species of corals were
recorded in the present study (30 species – past data) and the recorded species are
Acropora corymbosa, A. formosa, A. hyacinthus, A. humilis, Montipora digitata, M.
foliosa, M. spumosa, Turbinaria peltata, T. crater, Leptoria phrygia, Goniastrea
pectinata, Goniastrea retiformis, Hydnophora exesa, Favia apllida, Porites solida, P.
mannarensis, Goniopora sp. Psammocora contigua, Merulina ampliata, Platygyra
Lamellina and Favites abdita.
Seagrass distribution
Seagrass beds occur all around the island covering an area of about
14 sq. km. Eleven species of seagrass are recorded and they are Cymodocea
rotundata, C.serrulata, Syringodium isoetifolium, Halodule uninervis, Halophila ovalis,
Halophila ovata, Thalassia hemprichii, Halophila ovata, Thalassia hemprichii,
Halophila stipulacea, Halophila decipiens, Halophila beccarii and Halodule pinifolia.
Mangrove Distribution
Dense distribution of Pemphis and other halophytic plants occurs in the
island. Two species of mangroves and 4 associated species are recorded. The
recorded species are Avicennia marina, Pemphis, Salvadora persica, Sesuvium sp,
Scaevola sp and Thespesia populnea.
3.3.5 Marine organisms recorded around
Keezhakarai Group Islands
Phytoplankton

In the Keezhakarai group, 53 species of Bacillariophyceae, 9 species of
Dinophyceae, 3 species of Cyanophyceae and 2 species of Chlorophyceae totalling
67 species of phytoplankton were recorded. Appa island exhibited maximum species
diversity. The phytoplankton count varied from 5-935 nos/ml.
Zooplankton
In the Keezhakarai group, 45 species of Crustacea, 1 species of
Granuloreticulosa, 1 species of Hydrozoa, 3 species of Polychaets, 1 species of
Polyhymenophora, 1 species of Sagittoidea and 2 species of Thaliacea totalling 54
species of zooplankton were recorded. Appa island exhibited maximum species
diversity. The density of zooplankton varied from 1000-9000 nos/cu.m.
Coral distribution
In the Keezhakarai group, 6 species of Acropora, 3 species of Montipora, 4
species of Porites, 2 species each of Favia, Goniastrea & Turnbinaria, 1 species each
of Coscinarea, Echinopora, Favites, Galaxea, Goniopora, Hydnopora, Leptoria,
Merulina, Pavono, Platygyra, Pocillopora and Psammocora totalling 31 species of
corals were recorded. Maximum number of coral species were recorded around
Anaipar and Kulli Islands.
Benthos distribution
In the Keezhakarai group 1 species of Porifera, 32 species of Cnidaria, 1
species of Annelida, 7 species of Mollusca, 12 species of Arthropoda and 3 species of
Echinodermata totalling 56 species of benthic organisms were recorded. Anaipar and
Valimunai islands exhibited maximum species diversity.
Ornamental fishes distribution
100 species of ornamental fishes were recorded around the Keezhakarai
group. The dominant species were recorded in the families of Pomancentridae,
Chaetodontidae, Lutjanidae and Holocentridae.
Capture fishes
In the Keezhakarai group 5 species of Chondrichthyes (Elasmobranch), 54
species of Actinopterygii (Teleostei), 9 species of Crustaceans and 4 species of
Cephalopodas, totalling 72 species were recorded.
3.3.6 Vembar Group

The Vembar group consists of three islands. Patch reefs are found around the
islands and fringing reefs occur along the southern side at a distance of about 500 m.
Dugong foraging grounds are extensive around Nallathanni island. Dense distribution
of mangroves occurs in Upputhani Island. 25 species of coral, 11 species of seagrass
and 3 species of mangroves are found in the Vembar group of islands.
Live corals are found beyond 0.5 m depth. Maximum number of live coral
points exists around Upputhanni islands. Coral reef area around the islands is about
12 sq. km. Seagrass covers an area of about 9 sq.km. around the islands.
3.3.6.1 Nallathanni Island
Nallathanni island is the second largest island apart from Musal island in the
Gulf of Mannar. It is located about 10 km from Vembar and covers an area of area of
about 110 ha. The island as its name suggests has potable water.
Coral distribution
Coral reef and coral boulders occur all around the island at a distance of
400-500 m on the southern side and very close to northern shore. Coral reef covers
an area of about 2 sq.km. Live coral coverage is about 38%. Twenty species have
been recorded in the current study. The recorded species are Sarcophytum sp.,
Montipora foliosa, M. spumosa, M. digitata, Turbinaria peltata, T. crater, Favia
pallida, Favia sp. Fvites abdita, Goniastrea pectinata, Goniastrea retiformis,
Hydnophora sp, Goniopora sp Porites lutea, Porites solida, Acropora formosa, A.
hyacinthus, A. corymbosa, Symphyllia radians, Leptoria phrygia, Galaxea
fascicularis and Psammocora contigua.
Seagrass distribution
Seagrass around the island covers an area of about 5 sq. km.
Eleven species of seagrass have been recorded. The recorded species are
Cymodocea rotundata, C. serrulata, Syringodium isoetifolium, Halodule uninervis,
Halophila ovalis, Halophila ovata, Thalassia hemprichii, Halophila stipulassia,
Halophila decipens, Halophila beccarii and Halodule pinifolia.
Mangrove distribution

Dense distribution of Pemphis and other halophytic plants occurs in the
island. One species of mangroves and 4 associated species are recorded. The
species are Pemphis acidula, Salvadora persica, Sesuvium sp. and Thespesia
populnea.
3.3.6.2 Pulivinichalli Island
Pulivinichalli Island is located about 8 km from Vembar and covers an area of
about 6 ha. The island is characterised by sandy beach and thick vegetation. The
eastern side of the island has sparse distribution of Thespesia.

Coral distribution
Coral reefs were found in the southern side of the island. A huge mass of
dead coral stones and boulders were found in the northwest corner of the island which
extended upto a distance of 1.5 km. Coral reefs cover an area of about 7 sq.km. Live
coral coverage is about 38%. Seventeen species have been recorded (41 species -
past data) in the current study and they are Montipora digitata, Montipora foliosa,
Montipora spumosa, Montipora turgescens, Favia pallida, Favites sp, Porites lutea,
Porites solida, Gonistrea retiformis, Leptoria phrygia, Acropora formosa, A. hyacinthus,
A. humilis, A. nobilis, A. corymbosa, Turbinaria crater and Pocillopora damicornis.
Seagrass distribution
Seagrass occurs all around the islands covering an area of about
1.5 sq. km. Eleven species of seagrasses have been recorded and the species are
Cymodocea rotundata, C. serrulata, Syringodium isoetifolium, Halodule uninervis,
Halophila ovalis, Halophila ovata, Thalassia hemprichii, Halophila stipulacea, Halophila
decipiens, Halophila beccarii and Halodule pinifolia.
Mangrove distribution
Pemphis and other halophytic plants occur in the island. One species of
mangrove and 4 associated species are recorded. The dominant species are Pemphis
acidula, Salvadora Persica, Sesuvium sp, Scaevola sp and Thespesia populnea.
3.3.6.3 Upputhanni Island
Upputhanni island is located 8 km from Vembar and covers an area of about
30 ha. The island is fairly big with plenty of coral rubble all over it. A number of trees
along with numerous bushes are present
Coral distribution
Fringing reefs occur at a distance of 150 to 300 m all around the island except
in the north. Coral reefs cover an area of about 3 sq. km. Live coral cover is about
28%. Sixteen species of corals are recorded in this study and they are Montipora
digitata, Monitipora foliosa, Montipora spumosa, Montipora turgescens, Favia pallida,
Favites sp, Porites lutea, Porites solida, Goniastrea retiformis, Hydnophora exesa,
Turbinaria peltata, T. crater, Leptoria phrygia, Acropora corymbosa, Psammocora
contigua and Symphyllia radians.
Seagrass distribution

Seagrass occur all around the islands covering an area of about
2.5 sq. km. Ten species of seagrasses have been recorded and they are Cymodocea
serrulata, Syringodium isoetifolium, Halodula uninervis, Halophila ovalis, Halophila
ovata, Thalassia hemprichii, Halophila stipulasia, Halophila decipiens, Halophila
beccarii and Halodula pinifolia.
Mangrove distribution
Dense distribution of mangroves occurs in the southeastern side of the island.
Three species of mangroves and 4 associated species are recorded and the species
are Avicennia marina, Rhizophora mucronata, Pemphis acidula, Salvadora persica,
Sesuvium sp., Scaevola sp. and Thespesia populnea.
3.3.7 Marine Organisms around Vember Group of Islands
Phytoplankton
In the vembar group, 48 species of Bacillariophyceae, 11 species of
Dinophyceae, 2 species of Cyanophyceae and 1 species of Chlorophyceae, totalling
62 species of phytoplankton were recorded. Nallathanni island exhibited maximum
species diversity. The phytoplankton count varied from 6 - 478 nos/ml.
Zooplankton
In the vembar group, 37 species of Crustacea, 1 species of Hydrozoa, 1
species of Polychaeta, 1 species of Polyhymenophora, 3 species of Saggitoidea and 1
species of Thaliacea totalling 45 species of zooplankton were recorded. Maximum
number of species was recorded around Pulivinichalli and Upputhanni islands. The
density of zooplankton varied from 1000-9000 nos/cu.m.
Coral distribution
In the Vembar group, 5 species of Acropora, 4 species of Montipora,
2 species each of Porites, Goniastrea and Turbinaria, 1 species each of Favia,
Favites, Galaxea, Hydnopora, Goniopora, Leptoria, Pocillopora, Symphyllia,
Psammocora and Sarcophytum totalling 25 species of corals were recorded.
Maximum number of coral species was recorded around Nallathanni island.
Benthos distribution
In the Vembar group, 1 species of porifera, 27 species of Cnidaria,
7 species of Mollusca, 8 species of Arthropoda and 2 species of Echinodermata

totalling 45 species of benthic organisms were recorded. Nallathanni island exhibited
maximum species diversity.
Ornamental fishes distribution
128 species of ornamental fishes were recorded in the Gulf of Mannar.
Around 104 species of ornamental fishes were recorded around the Vembar group.
The dominant species were recorded in the families of Pomacentridae,
Chaetodontidae, Labridae and Apogonidae.
Capture fisheries
In the Vembar group, 8 species of Chondrichthyes (Elasmobranchs), 69
species of Actinopterygii (Teleostei), 9 species of Crustaceans and 5 species of
Cephalopods, totalling 91 species were recorded.
3.3.8 Tuticorin Group
The Tuticorin group consists of four islands, one of, which is submerged. Reef
patches exist all around the islands. The islands have sparse vegetation. Twenty three
species of corals, 11 species of seagrass and
3 species of mangroves and asociated species are found in the Tuticorin group of
islands.
Live corals are found beyond 0.5 m depth. Maximum number of live coral
points exists around Karaichalli island. Coral reef area around the islands is about 10
sq. km. Field survey was carried out during March 2000, in all four islands for mapping
the extent of seagrass. Seagrass covers an area of about 10 sq.km.

3.3.8.1 Karaichalli Island
Karaihalli island is about 15 km from Tuticorin. It covers an area of about 16
ha and has very poor vegetative cover. Fishermen from the nearby mainland visit the
island for illegal coral mining operations.
Coral distribution
Patches of coral reef exist all around the island and cover the area of 0.31
sq.km. Live coral coverage is about 14%. Twenty five species of corals have been
recorded and the species are Acropora hyacinthus, A formosa,
A nobilis, Acropora sp., Montipora digitata, M. foliosa, M. foliosa, M. spumosa, Favites,
abdita, Favites sp., Favia pallida, F. favus, platygyra, T. crater, Goniastrea, retiformis,
G. pectinata, Galaxea fasicularis, Symphyllia radians, Leptastrea transversa, Leptoria
phrygia and Goniopora stokesi.
Seagrass distribution
Seagrass occur all around the islands covering an area of about 1 sq km.
Eleven species of seagrass have been recorded . The recorded species are
Cymodocea rotundata, C. serrulata, Sysringodium isoetifolium, Halodule univervis,
Halophila ovalis, Halophila ovata, Thalassia hemprichii, Halophila stipulacea,
Halophila decipiens, Halophila beccarii and Halodule pinifolia.
Mangrove vegetation
There is sparse distribution of Pemphis and other halophytic plants in the
island. Two species of mangroves and 4 associated species are recorded. The
dominant species are Avicennia marinam, Pemphis acidula, Salvadora persicam,
Sesuvium sp, Scaevola sp and Thespesia populnea.
3.3.8.2 Vilanguchalli island
Vilanguchalli island is completely submerged and gets exposed during low
tide. The island is located at about 15 km. from Tuticorin.
Coral distribution
Coral reef patches occur all around the submerged island. Coral reefs cover
an area of about 1 sq. km. Live coral coverage is about 8%. Eight species of corals
were recorded in the current study (21 species- past data) . The recorded species

are Acropora hyacinthus, A formosa, Montipora spumosa, Favia pallida, porties
lutea, Turbinaria crater, Goniastrea retiformis and Leptastrea sp.
Seagrass distribution
Seagrasses occur all around the island covering an area of about
1.5 sq. km. Eleven species of seagrass have been recorded and they are
Cymodocea rotundata, C. serrulata, Syringodium isoetifolium, Halophila stipulacea
and Halophila decipiens.
3.3.8.3 Kasuwar Island
Kasuwar is the largest and elongated island in the Tuticorin group and is
located at about 7 km from Tuticorin. The island is sandy and strewn with shingles and
covers an area of about 19 ha. The whole island is covered with xerophytic vegetation.
Coral distribution
Coral reef patches occur all around the island. Coral reefs cover an area of
about 6 sq. km. Live coral coverage is about 5%. Fourteen 14 species are recorded
and the species are Acropora hyacinthus, A formosa, Montipora digitata, M. foliosa,
Favites abdita, Favia favus, Platygyra lamellina, Porites mannarensis, Turbianria
Peltata, T. crater, Goniastrea retiformis, Goniastrea sp., Goniopora stokesi and
Leptoria phrygia, Digitata, M. foliosa, M. spumosa, Favites abdita, Favites sp, Favia
pallida, Platygyra lamellina, Porites lutea,
P. mannarensis, Hydnopora sp., Turbinaria peltata, T. crater and Goniastrea
retiformis.
Seagrass distribution
Seagrass occurs all around the island covering an area of about 5 sq. km.
Nine species of seagrass have been recorded and they are Cymodocea serrulata,
Syringodium isoetifolium, Halophila ovalis, Halophila ovata, Thalassia hemprichii,
Halophila stipulacea, Halophila decipiens, decipiens, Halophila beccarii and Halodule
pinifolia.
Mangrove distribution
Pemphis and other halophytic plants occur in the island. Two species of
mangroves and 4 associated species are recorded. The recorded species are

Avicennia marina, Pemphis acidula, salvadora percisa, Sesuvium sp, and Thespesia
popuinea.
3.3.9 Marine Organisms aroung Tuticorin Group of Islands
Phytoplankton
In the Tuticorin group, 4 species of Bacillariophyceae, 8 species of
Dinophyceae, 5 species of Chlorophyceae totalling 70 species of phytoplankton were
recorded. Kasuwar island exhibited maximum species diversity. The phytoplankton
count varied from 2-835 nos/ml
Zooplankton
One species of Granuloreticulosa, 1 species of Hydrozoa, 3 species of
Polycheata, 5 species of Polyhymenophora, 1 species of Sagittoidea and
2 species of Thaliacea totalling 59 species of zooplankton were recorded. Van island
exhibits maximum species diversity. The zooplankton count varied from 1000 –
10,000 nos / cu.m.
Coral
In the Tuticorin group, 3 species each of Acropora, Montipora and Porites, 2
species each of Goniastrea, Turbinaria and Favia, 1 species each of Favites,
Galaxea, Hydnopora, Goniopora, Leptoria, platygyra and Symphyllia, totalling 23
species of corals were recorded. Maximum number of coral species was recorded
around Karaichalli island.
Benthos
In the Tuticorin group, 1 species of Porifera, 24 species of Cnidaria, 4
species of Mollusca, 3 species of Arthropoda and 2 species of Echinodermata,
totalling 34 species of benthic organisms were recorded Kasuwar island exhibited
maximum species diversity.

Ornamental Fishes
In the current study (1998-99), 128 species of ornamental fishes were
recorded in the Gulf of Mannar. 101 species of ornamental fishes were recorded
around Tuticorin group. The dominant species were recorded in the families of
Pomacentridae, Cheatodontidae, Mullidae and Lutjanidae.
Capture fisheries
In the Tuticorin group, 14 species of Chondichthryes (Elasmobranchs), 96
species of Actinopterygii (Teleost), 11 species of Crustaceans and 5 species of
Cephalopods, totalling 126 species were recorded.
3.4 Palk Bay/Palk Strait
3.4.1 Marine Water Quality
Marine water quality in Palk Bay area near the proposed channel is assessed
from secondary data and is summarised in Table 3.40. It is observed that suspended
solids vary from 28-30 mg/l at the surface and is uniformly distributed up to bottom.
The could be due to shallow depths 2-12 m in Palk Bay. Salinity is observed to vary
from 30.4-32.5 parts per thousand. High dissolved oxygen (DO) levels at the surface
are indicative of healthy aquatic life and low organic pollution loads particularly away
from the coastal areas. DO was observed to decrease towards bottom and is
attributed to demand excercised by sediment. Observed levels of nitrogen and
phosphorus support biological growth. Heavy metals were in traces and levels of
polynuclear aromic hydrocarbons observed in parts per billion (ppb) levels. This could
be attributed to fishing activity in the region.
3.4.2 Biological Productivity
The Palk Bay is biologically rich and are rated among the highly productive
seas of the world. The Palk Bay is endowed with a combination of ecosystem
including mangroves, seagrass and coral reefs, supporting over 3,600 species of
plants and animals. Its biodiversity is considered globally significant. The Palk Bay
islands constitute a resting-place for birds migrating to and from Sri Lanka.
Approximately 168 types of birds use the islands in this area as a resting-place while
migrating or as wintering and molting grounds. All five species of marine turtle nest in
various locations in Palk Bay. Dolphins are more common here than in any other

region in the Bay of Bengal. The endangered dugong uses many of the islands as
browsing grounds. Marine life also includes many colored coral fishes, eels, molluscs,
and stomatopoda. Sea anemones, crabs, starfishes, sea urchins and numerous other
organisms are found in the Palk Bay.
Biological diversity of Palk Bay/Palk Strait is in influenced by point colimer
sanctuary which is bestowed with mangrove forests, mud flats, wettalnds and brackish
to saline lagoons. The sanctuary provides breeding ground for marine fishes which are
vital to the fisheries of the region. The sanctuary has been designated as Ramsar site
in November 2002 by world wildlife fund (WWF) - India.
3.4.2.1 Primary Productivity
Primary productivity in the offshore area was relatively less than in the shelf
and slope area for Palk Bay region. The productivity at surface is more than
subsurface layers. The southwest monsoon was more productive compared to
pre-monsoon season. Phytoplankton analysis showed that diatoms contributed 70%,
flagellates 23% and dinoflagellates 7%, of the biomass at the surface.
Integrated values of chlorophyll at the surface along Palk Bay is
<0.1 mg/m3 and at 0-50 m and 0-100 m depth it is 5-15 mg/m2. The gross primary
productivity values varied from 143 to 472 mgC/m3/day. The mean values are 205
mgC/m3/day for Palk Bay. It is further reported that in the near shore areas where the
euphotic zone used to be about 6 m due to turbidity, the productivity was reported to
be 1.2-1.5 gC/m2/day which is equal to the annual gross productivity of about 450
gC/m2. While further inside the sea where the euphotic zone is deeper (upto 15-40 m),
the average daily productivity used to be 3-5 gC/m2 (Nair 1970). The average primary
productivity values in central ocean basins and coastal zones of the world were
estimated at 50 and
2
100 gC/m /yr respectively (Ryther, 1969). Thus, the shallow regions of Palk Bay
constitute one of the most productive regions of the world. It is also clear from the
above that turbidity adversely affects primary productivity.
Link in the Food Chain
As already mentioned, the phytoplankton constitute the food for the smallest
of animals, viz. zooplankton which in turn form the food of the largest mammal, the
Antarctic whale (Balanoptera) which feeds on small shrimp like zooplankton known as

krill (Euphausia superba). The krill is wholly dependent on the bloom of phytoplankton
for its survival and growth. The largest of the fishes, the basking shark, is also a
planktonic feeder, mainly feeding on the copepod Calanus which in turn survives on
the phytoplankton. The fishery for oil sardine and mackerel are entirely dependent on
the bloom of phytoplankton. There are several other fishes and mammals in the sea
whose life is linked with phytoplankton, only the number of links in the food chain vary
in each instance. Each species has its own period of growth and growth intensity
depends on many external factors such as temperature, salinity, nutrients and the
physiological state of the species itself and these in turn are influenced by seasons
and climatic factors.
Productivity and Potential Yield
In Palk Strait area potential primary production during June-September,
average for surface layer 0-50 m is 10-15 mg C m-3h-1 and for December-March it is
<10 mg Cm-3h-1.
Primary productivity in SW & NE monsoon is 0.56 & 0.23 g C m-2 day-1 and 101
and 60 g C m-2 180 day-1.
Peak Periods of Production
The maximum production occurs during the south west monsoon season,
followed by one or two peaks of production of lesser magnitude during the north east
monsoon season. The peaks of production are mainly due to the multiplication of
diatoms, dinoflagellates and nannoplankters. The blue-green algae chiefly composed
of filamentous bundle like structures called Trichodesmium occur generally during the
warmer months. Investigations on the factors responsible for the production of
phytoplankton have shown that during the monsoon months, optimum condition such
as abundance of nutrients due to upwelling and river discharge fall in temperature and
salinity are common features of these waters. The nature of phytoplankton flora
changes frequently and each species appears to have its own peak periods of
occurrence and associations. The species which contribute to the bulk during periods
of maxima also vary from year to year, though a few appears to be common. A total of
56 species of phytoplankton have been observed from Palk Bay / Palk Strait.
3.4.2.2 Secondary productivity

The secondary productivity is influenced by the dominance of ostracods,
decapods, mysids and other zooplanktonic forms. The distribution of zooplanktons in
Palk Bay assessed from secondary data is shown in Table 3.41.
Ostracods
Ostracods are tiny bivalve crustaceans more during April, followed by July,
that may be attributed to high temperature, salinity and dissolved oxygen of the
bottom water, high calcium carbonate and low organic matter content of the
sediments. The most congenial substrate for better thriving of the fauna are found to
be silty - sand. About 51 ostracod species (both living and dead forms) belonging to
40 genera in 22 families were identified of which the following
8 spp are considered to be abundant viz. Actinocythereis scutigera, Bairdoppilata
atcyonicola, Callistocy flavidofusca C. intricatoides, Cytherelloidea leroyi, Keijella
reticulata, Loxoconcha gruendeli, L., mandiensis and Tanella gracilis.
Decapoda
Decapods are Prawns and Shrimps. Both the type of animals are having 10
sets of legs. They are highly sensible creatures and occur mostly beyond
50 m depth. Distribution of decapods in Palk Bay is shown in Table 3.42.
Mysids
A rich and varied mysid fauna exist in the littoral and shallow areas of the
seas around Palk Bay / Palk Strait. Reports on the abundance of mysid population
reveal a greater concentration (74%) in the nighttime collections indicating diel
migrations, characteristics of the fauna. The population density is high during the post-
monsoon (October-January) in the shelf waters and during the pre-monsoon
(February-May) in the oceanic region. The population of mysids occurred throughout
the year even in the deeper layers beyond 200m. The predominance is prominent
(63%) during the pre-monsoon and to lesser extent (23%) in the northeast monsoon
seasons in the neritic area.
Other zooplanktonic forms
Meroplanktonic stages of Anthozoan larvae is 4-6 nos of individual under 1
m2 area. Chaetognaths types are Pterosagitta draco, Sagitta bedoti, Sagitta enflata,
Sagitta pacifica and S. reularis commonly present during
SW & NE monsoon; Sagitta bipunctata are only observed during NE monsoon , while,

Sagitta neglecta only during SW monsoon. Distribution of copepoda is 9000-26999
nos/haul. Epiplanktonic calanoid observed are Clausocalanus minor, C. farrani,
Pontellina plumata and Eucalanus elongates. Other species in vicinity are
Centrophagus furcatus and Temora discaudata. Day and night collection of pelagic
amphipods during April-October has density of 26-50 and 51-100 nos/ m2, while, for
October-April, it is 100-250 nos under 1 m2 net area scanned upto 200 m depth. The
distribution of euphausiids : Pseudoeuphausia latifrons and Nyctiphanes capensis
during May-September and November-March is 1-249 nos/1000 m3 of water; for E.
distinguenda and E. diomediae it is 1-499 nos/1000 m3 from November to March. The
larvae, juveniles and adults of ‘Nematoscelis gracilis’ were observed only during
November-March. The Gastropoda ‘Limacina inflata’ were observed only during night-
time from April to October & vice-versa, the catch being 11-100 per haul.
Zooplankton biomass during March-April is 40-80 ml m-2 / haul at 200 m
column, whereas, for May-June it is 10-20 ml m-2/haul; for July-September it is 0.1-
10.0 ml m-2/haul and for December-February it is 10-20 ml m-2/haul.
Secondary stock and secondary production in SW & NE monsoon is
101 & 60 g C m-2 180 day-1.
Bottom Water Characteristics
The temperature range of 22.3 to 28.6OC seems favourably for all living population
of zooplankton fauna, throughout the year. Salinity range from 32.93 to 35.81‰ favourable
for the standing crop. Dissolved oxygen content is one of the important factors governing
distribution and abundance of standing crop.
Sediment Characteristics
Distribution of zooplanktons in relation to the sediment composition reveals
that silty - sand followed by sandy - silt and sand are the most favourable substrates
for the population abundance.
Temporally, higher values of temperature, salinity, dissolved oxygen and
calcium carbonate are recorded in April whereas organic matter content is maximum
during January. Spatially, however, the values of all these environmental parameters
show steady increase except temperature. The organic matter content in the
sediments is 0.36 to 3.51 % by weight.

CaCO3 percentage in the sediment varies from 2.5 to 7.2 %, CaCO3 does
not show much variation. In general, CaCO3 content of the sediment is found to be
directly proportional to the population size and it is inferred that it is one of the
important parameters that governs the population size, especially its spatial
distribution.
3.4.2.3 Tertiary productivity
The tertiary production in SW & NE monsoon is 20-40 & 10-20x105 tons wet
weight.
3.4.2.4 Benthos
Sediments led to the recognition of 108 benthic species consisting of both
living and dead fauna. They belong to 50 genera, 27 families and 10 superfamilies.
Among the 108 species, 12 species (viz. Rhabdommina scabra, Ammonbaculites
exiguus, Textularia agglutinans, T. aura, T. candeiana, T. conica, T. foliacea, T.
foliacea var occidentalis, T. palustris. Bigenerina irregularis, Trochammina inflata
and Eggerella advena) are arenaceous agglutinated (suborder Textulariina); 43
species are calcareous porcelaneous (viz. Edentostomina cultrata, Spiroloculina
angulata, S. communis, S. corrugata, S. costifera, Spiroloculina sp., Vertibralina
striata, Quinqueloculina agglutinana, Q. bicostata, Q. bidenta Q. compressa, Q.
lamarckiana, Q. parkeri, Q. polygona,
Q. pseudoreticulata, Q. rameswarensis, Q. seminulam, Q. sulcata, Q. tenagos, Q.
undulose costata, Pseudomassilina australis, P. australis, P. reticulata, P. macilenta,
Pyrgo elongata, P. subspherica, Triloculina carinata, T. striata, T. insignis, T.
schreiberiana, T. terquemiana, Milolinella circularis, M. labiosa, Hauerina bradyi, H.
fragilissima, Articulina mayori, Parrina bradyi, Peneroplis plantus, Monalysidium
politum, Spirolina acicularis S. arietinus, Sorities marginalis and S. orbiculus
(Suborder Miliolina) and the rest 53 are calcareous perforate forms (viz. Lagena
costata amphora, L. gracillima, L. laevis, L. setigara, L. striata, Guttulina sp.
Fissurina marginata, Bolivina doniezi, B. lanceolata Brizalina lowmani, B. striantula,
Rectobolivina glabro, R. raphanus, Chrysolidinella dimorpha, Reusella atlantica,
Rosalina globularis, R. valvulata granulosa, Cancris oblonga, Spirillina vivipara,
Ammonia beccarii, A. dentata, A. tepida, Asterorotalin inflate, A. trispinose,
Pararotalia nipponica, P. azawai, Pseudorotalia sehroeteriana, Calcarina umblicats,

Elphidium advenam, E. crispum, E. discoidale, E. excavatum, E. hispidium, E.
incertum, E. limbatum, E. poeyanum, E. verriculatum, Poroeponoides laterolis,
Cibicides lobatulus, C. refulgens, Planorbulina mediterranensis, Planorbulinella
larvata, Acervadina inhaerens, Cymbaloporetta bradyi, C. squammosa, Fursenkoina
compressa, F. punctata, Sigmavirgulina tartuosa, L. limbatum costudata, Florilus
boucamum, F. grateloupi, F. labradoricum and O. venusta (sub order Rotaliina).
Among living forms, only the eight taxa (viz. Spiroloculina insignis, T.
trigonula, Ammonia beccarii, A. tepida, Pararotalia nipponica and Osangularia
venusta) are considered to be widespread and abundant in the Palk Bay area.
3.4.3 Sponges and corals
Sea - Cucumbers
Sea cucumbers are a group of economically important echinoderms with a
wide range of distribution in coral to mangrove habitats.
Although nearly 200 species of sea cucumbers are distributed in the seas
around India, only about a dozen species are of commercial importance. Only
species belonging to the families Holothuridae and Stichopodidae are of commercial
importance since they are large in size and the body wall is also thick. These are
distributed in good numbers in the Palk Bay. Nearly 30 corals are recorded from
Palk Bay (Table 3.43).
Species observed are, Family, Holothuriadae, sp., Actinopyga miliaris,
A.mauritiana, A echinites, Bohadschiaargus, B. marmorata, Holothuria nobilis, H.
atra, H. scabra, H. spinifera, Family-Stichopodidae, sp., S. chloronotus, S.
variegatus.
Flourishing export market for the processed sea cucumbers has increased
their exploitation. Over 60% of beche- de-mer exported from India, is from the Palk
Bay. Sea cucumbers are mostly collected by skin divers in shallow waters from 2-10
m depth. Presently, operation of a modified trawl net called Chanku madi yields good
catches of sea cucumbers alongwith chanks (Xancus pyrum). The harvest
composition of this gear is Xancus pyrum (61.22%), sea cucumbers (20.4%), rays
(Amphotistus kuhlii) (16.33%) and starfish, sea shells and small fishes (2.04%).
Holothuria being detritus feeders are found among the marine macro-algae and
seaweeds.

Sea fan
The Sea fan is yet another colonial form, but it branches only in one plane
and the branches may fuse with each other to form a 'fan'. White or cream-colored
polyps may grow on a base of contrasting maroon colour, attached to stones by a
broad disc-like holdfast. Gorgonides are reported in Palk Bay in deeper waters,
beyond 50 m (CMFRI 1998). The colorful sea fans have long been objects of attraction
to man. Gorgonid community is popularly known as \"flowers of under water gardens\".
Sponges
Sponges, although at a casual glance look like plants, are animals, living
singly or in colonies. They have no fixed shape, and form flat encrustations on stones
in the region of strong waves. In the crevices, these sponges are found associated
with many animals, ranging from tiny crabs and brittle star to bivalve molluscs.
Sponges show commensalisms as several crustaceans, worms, molluscs and fishes
live in the internal cavities of sponges for protection against enemies, and also act as a
shelter bed. About, 60 desmosponges are recorded from Palk Bay (Table 3.43).
3.4.4 Fishing in Palk Bay
The distribution and abundance of different groups of fish in the areas are
shown in the Table 3.44. It is evident that highest catch was recorded for
Pomadasys, Leiognathus and Lethrinus sp. Along Palk Bay region, very high values
of organic production to the tune of 435 mgC/m/day to 2340 mgC/m/day were
reported from June to July. The threadfin breams along SE coast of Palk Bay
(10O/18O) has no catch at all upto depths from 40-100 m. The depth range of 60-90
m along 10ON Lat. of SE coast (Palk Bay) has only one form of threadfin breams as
Nemipterus japonicus (100%). Off the south east coast the fishing area at 10O/80O
has recorded the highest catch of 1,033 kg/hr with major perches (Pristipomoides
typus, Epinephelus and Lutjanus) forming the bulk. The abundance of demersal fin
fish kg/hr along Palk Bay (10O/80O) in Table 3.45 shows the dominance of fish in the
order Carangids>Perches> Rastrelliger> miscellaneous fish between 51-100 m
depth, whereas there is no catch below
50 m depth. Other types of fishes (13 types) are not found in this area. The perches
in SE coast at 10ON below 50 m show presence of serranids, whereas at depth 51-

100 m Lutjanus, Lethrinus, Plectorhynchus and other perches are uniformly caught
(Table 3.46).
3.4.5 Marine Mammals
The cetacea (whales and dolphins) and sirenia (sea cow) represent the
main groups of marine mammals in the Palk Bay. Marine mammals have a layer of
dermal fat or blubber. This acts as a stored reserve food for future use in case of
deficiency of food. The sirenia (sea cow) graze with their well developed lips, in
consequence, their teeth are little used and are greatly reduced in size. In cetacea,
whales and dolphins are mostly carnivorous and feed on crustaceans, squids, and
fishes. In sirenia, sea cow is herbivorous and feeds mainly on sea grasses.

Dolphins and Whales
The dolphis found in the Palk Bay are oceanic and roam about in the area. It
is most likely that only the frail and the infirm whales move towards this area as
known from strandings of whales. So far no mass stranding of whales has been
observed in the canal area. The dolphins Stenella longirostris and Tursiops truncatus
are often caught in various nets and the ones thus caught and injured (probably) are
clandestinely butchered for food. However, capture or harming of the sea mammals
is prohibited by law.
Sea Cow
Unlike dolphin and whales, sea cow (Dugong dugon) inhabits the Palk Bay
preferably within 10 m depth limit not far from the shore (1-3 km). Usually sea cows
move in groups of 5-7 among the seagrass Cymodocea, which is its chief diet. The
dugong which grows to over 300 kg measuring 1-1.5 m in length, is harmless and
sluggish in nature. Its gestation period lasts 13-14 months and gives birth to a single
calf at a time. Though young male adults compete among themselves for female,
once they have paired, they remain paired for the whole life. Their attachment to the
partner and calf is such that if one of the partners or calf gets caught the rest also
shall follow; thus becoming easy victims. They have no natural enemies except the
civilised man. The exact number of sea cows living in the Palk Bay is not known.
Due to uncontrolled fishing carried out till recently and also due to reduction in their
grazing area and Cymodocea, their numbers have gone down drastically. During
1980's, about 200 numbers used to be killed per year. Now they are protected by the
Wildlife (Protection) Act, and are under threatened status. Occasionally, marine
mammals and turtles have been observed to get washed ashore, and on
examination it is found that the death is often due to propeller cuts or eating of
floatsam.
3.4.6 Distribution Of Palk Bay Reef
The reef in Palk Bay runs parallel to land (east to west direction) from
Pamban Channel at the Pamban end of the bridge to Rameswaram island between
longitudes 79° 17' E and 79° 8'E at the latitude 9° 17'N. The Bay is a very shallow flat
basin and the depth never exceeds 15 metres. The average depth is 9 meters. The
coral reef in Palk Bay starts from Munakad as a wall-like formation 1-2 m broad and

runs east upto Tonithurai a distance of nearly 5.5 km. Here the reef width is more than
300 metres. East of Pamban pass, the reef again starts near Thangachimadam and
ends near Agnitheertham (Rameswaram) (Mahadevan and Nair, 1969). This reef is
25-30 km long and generally less than 200 m wide. Visibility is poor due to siltation.
The Palk strait between India and Ceylon is about 75 km wide, with a water depth of 9-
13 m, except where local coral reef rises above sea level.
Coral reefs on the Tamil Nadu coast (south east coast) are located in Palk
Bay near Rameswaram and in the Gulf of Mannar. Mandapam peninsula and
Rameswaram Islands separate Palk Bay from the Gulf of Mannar. The reef is
centered at 9O17’ N and 79O15’ E. There is only one fringing reef in the Palk Bay,
which lies along the mainland from the Pamban channel at the Pamban end of the
bridge to Rameswaram Island. This reef is 25-30 km long, and generally less than
200 m wide; maximum depth is around 6 m. Visibility is poor due to siltation and it is
influenced by the north east monsoon. The reef flat is relatively broad from Pamban
channel to the southern end near Ramnad and narrow from Pamban to south of
Rameswaram.
3.4.7 Review of the Coral Reef Ecosystem of Palk Bay
Gopinadha Pillai (1969) classified the reefs of Palk Bay into five zones -
shore, lagoon, shoreward slope, reef crest and seaward slope. The shore of the reef
is mostly sandy with dead pieces of corals, except at the extreme eastern and near
the Pamban bridge where one can see traces of sandstone. The vegetation on the
shore comprises Cocos nucifera, Borassus flabellifera, Casurina equisetifolia,
Azadirdicata indica and few other thorny shrubs.
The width of the lagoon varies from 200 to 600 meters at different places
with a depth of 1 to 2 metres. The bottom is sandy with molluscan shells and pieces
of disintegrating corals. Living corals are practically absent in the lagoon, probably
due to the absence of any hard substratum on which coral planulae can settle.
Sponges such as Hercina fusca, Dysidea fragilis,
Spirastrella inconstans and Calispongia diffusa are fairly common at the bottom. The
vegetation is composed commonly occurring of Cymodocea sp., Ulva reticulata,
Turbinaria sp., Padina sp., Halimeda sp. and Amphiora sp. Holothuria scabra,

Holothuria arta and Pentaceraster australis are common inhabitants of the sandy
lagoon floor (Pillai, 1969).
Corals distributed along the shoreward slope are encrusting and of massive
types with comparatively large polyps, such as Favia pallida, Favus, Favites virens,
Goniastrea pectinata, G. retiformis, Platygyna lamellina, Hydrophora sp., Cyphastrea
sp., Leptastrea sp., symphillia sp. and Goniopora sp. Living colonies of Ponies sp
are rare or small in size. Galaxea fascicularis and Turbinaria peltala, Pavona varians
are the rarest species. This zone of the reef supports a good many reef dwellers like
encrusting sponges, bryozoans and calcareous algae. Among the fleshy corals
Lobophylum sp and Sarcophylum sp are represented.
The reef crest is often completely exposed at low tides. Corals are very rare
at the reef crest, probably because of the influence of exposure to sun light. However
Heptastrea transversa and Goniopora duofaciata are occasionally seen under the
rocks.
The coral growth of the reef along the seaward side slope is comparatively
richer than on the shoreward side. Majority of corals are ramose genera viz.,
Pocillopora sp, Acropora sp and Montipora sp. The vegetation comprises of
Turbinaria sp, Sargassum sp, Padina sp, Caulerpa sp and rarely Cymodocea sp.
Halimeda sp and a few other encrusting calcareous algae are commonly seen.
A total of 61 species of algae has been collected. They are distributed
among the three major groups - green algae (14 genera and 28 species), brown
algae (8 genera and 13 species) and red algae (17 genera and 20 species). The
frequency occurrence of different species in the quadrate samples show that
Halimeda opuntia is the dominant algal member of the reef. Species of Caulerpa and
Sargassum are the other most common plants found in the reef. The physical
conditions such as the nature of the substratum and water level above the
substratum influence the distribution of flora in the coral reef area (Umamaheswara
Rao, 1989). Boring sponges is the major group among the marine organisms
causing considerable destruction to the reef system. The bores made by the
sponges weaken the entire reef, making it more susceptible to the wear and tear
caused by the waves. There are altogether 20 known species of boring sponges
from the Gulf of Mannar and Palk Bay, falling into nine genera. The most

conspicuous genus is Cliona, both in number of species and in distribution (Thomas,
1969). Among the coral boring organisms, bivalve molluscs cause considerable
destruction to coral reefs. They act as biological agents in the erosion of hard coral
stones. In Palk bay and Gulf of Mannar, only 17 boring bivalve species have been
recorded from this area (under 10 genera of six families) (Appukuttan, 1969). Asir
Ramesh (1996) recorded a total of 73 species of molluscs associated with corals in
Palk Bay viz., 46 species of gastropods belonging to 17 families, and 27 species of
bivalves belonging to 13 families.
The dried sea horse (Hippocampus kunda) is in great demand in south-east
Asian countries, especially in Singapore and China - not only for extraction of soup
which is a delicacy but also for its medicinal values. Along the Ramnad coast, the
dried sea horse is used as a medicine to arrest whooping cough in children. The
dried sea horse is finely powdered and then roasted. This powder is mixed with
honey and administered as a engulfing medicine. In some places the powder is
mixed with coconut oil and pasted on the cut wounds. It is also used for curing
asthma (Marichamy et al., 1993).
Dugongs are long living animals with a low reproductive rate. They have a
long gestation period and a large gap between each off spring. Around 25 dugongs
were caught accidentally in this region during 1960. In Palk Bay Karangadu,
Nambuthaalai, Morepanai and Mullimunai are minor fishing villages. Valivalai (drift
net) shore seins and Thirukkaivalai are used to capture dugong in the shallow
regions. Explosives (Country bombs and dynamites) are used for capturing the
dugong in Thiruppalaikudi and Devipatnam (Ramnad District). During the 1960's the
fisherman of Palk Bay region bitterly complained about the disappearance of large
beds of algae owing to the cyclone in 1964, and turtles and dugongs almost
disappeared in this area. Fishermen, now report that the algal beds have sprung up
once again (Silas and Fernando, 1985).

3.4.8 Present Status of Palk Bay
Nearshore areas of Palk bay are polluted because of increased coastal
urban development. Sewage outlets are increasing the suspended load, turbidity,
nutrient etc. The coral reefs are under stress wherever processing industries let out
their sewage. The indiscriminate cutting of near shore forest, leads to coastal soil
erosion with huge quantities of nutrients that aggravate the physical stress on the
coral reef.
The Palk Bay lagoon has a width of around 230 m. from the shore. The
lagoon contains a large number of boulders, occupied by various species of
scleractinian corals. Table reef are also found in the lagoons. These newly found
boulders and table reef are formed by a process of wind drift. The green algae
population is greater in areas close to the sewage outlets of processing industries
than in healthy reef systems. Perna virdis, a rare component of the coral reef
ecosystem, is densely distributed in Palk Bay. Six scleractinian coral species are
recorded from the lagoon of Vellaperukkumanthai reef whereas Gopinadha Pillai has
identified two species (Porities somaliensis and Favia pallida) from the lagoon.
Fishermen suggest that the sponge population and soft coral population have
decreased over the past two decades. Our investigations also confirm an increase in
the boring sponge species and a decrease in the macrosponge species.
The shoreward slope of the reef has a width of 70 m in the area between
230 m and 300 m from the shore. The coral population has been increasing
remarkably in distribution and diversity along the shoreward slope. The 1969 record
of Gopinadha Pillai shows 11 species in this area, however, present investigation
shows 20 coral species with a density of 50 colonies/10m2. Padina sp and Halimeda
sp are most common algae present in this zone. The sponge population is
comparatively higher than in the lagoon. The coral species Platygyra lamellina,
Hydnophora sp, Galaxea fascicularis and Turbinaria pelata recorded by Pillai (1969)
are no longer present in Palk Bay.
Gopinadha Pillai recorded all the ramose corals in the seaward slope of the
reef. However, our present investigation shows that ramose corals are also
distributed along the shoreward slope and lagoon. The present study indicates that

10 scleractinian species are present in the seaward slope, whereas the previous
record (Gopinadha Pillai, 1969) shows only 6 species.
3.4.9 Wildlife Sanctuary Adjoining Palk Strait
Situated at the southern end of Nagappattnam district, Tamil Nadu the Point
Calimere region was first identified as an area of high conservation significance,
birds by the late Dr.Salim Ali in 1962. The sanctuary may be divided into three
divisions: the Point Calimere Forest; the GVS, which includes the mangrove forests
at Muthupet and the mangroves of TRF. It is the breeding ground or nursery for
many species of marine fishes, which are vital to the fisheries of the coast.
It is a marine - coastal wetland with a wide diversity of habitats and
ecological features, including: intertidal salt marshes, forested wetlands, mangroves
and brackish to saline lagoons. The sanctuary has been designated as a Ramsar
Site in November 2002.
The GVS is one of the largest waterbodies and major wintering
–
ground for waterbirds in southern India. The forests of Point
Calimere are also rich in both resident and migratory species of
forest birds. A total of 257 species of birds have been recorded
from the Sanctuary of which 119 are waterbirds and 138
forestbirds.
The wetland supports the vulnerable species spoonbill sandpiper
–
Eurynorhynchus pygmaeus and grey pelican Pelecanus
philippensis according to the IUCN Red List.
It supports about 30,000 flamingos, 200-300 endangered grey
–
pelican the endangered Asian dowitcher the rare spoonbill
sandpiper and tens of thousands of other waterbirds. A total of
119 waterbird species have been recorded from the area.
The wetland is the breeding ground or nursery for many species
–
of marine fishes which are vital to the fisheries of the coast. GVS
is the spawning and/or nursing ground for commercially important
prawns, crabs and fishes. Eastern part of the GVS harbours 23
fish species, mainly mullets, whereas the Mullipalam Lagoon at
Muthupet has a more direct influence of the sea and harbours

more marine species of fish, some 20 species.
Biodiversity Values
Flora
Due to the diversity of habitats, the vegetation of the Point Calimere Wildlife
Sanctuary is equally diverse, ranging from dry evergreen forests, mangrove
vegetation, salt marsh to grasslands.
The dominant trees of the forest are Manilkara hexandra and Salvadora
persica in the open areas. Insectivorous plants such as Drosera burmanii and
D.indica are also present in the grassland habitat. Dominated by Halophytes such as
Arthrocnemum indicum, Salicornia brachiata and Sessuvium portulacastrum are
common along the marshy areas of the shore. Patches of Prosopis chilensis,
Calotropis gigantea, Clerodendrum inerme and Pandanus tectorius occur in elevated
areas. Ipomoea pes- capre, Spinifex littoreus and Zoysia matrella are common on
the sand dunes. Avicennia marina is the dominant mangrove species in the area. At
Talaignayar, the vegetation is charateristic salt - marsh vegetation. During the
monsoon, aquatics such as Aponogeton natans, Bergia capensis, Najas graminea
and Sphenoclea zeylanica occur. Pentatropis microphylla is a common twiner on
many plants.
Fauna
Some of the major waterbird species are the greater flamingo and the lesser
flamingo, spot - billed pelican, spoonbilled sandpiper, Asian dowitcher, whitebellied
seaeagle, brahminy kite and osprey. Landbirds include paradise flycatcher, Indian
pitta, Rosy starling, Blyth reed warbler, crested serpent eagle and brown shrike.
Fourteen species of mammals have been reported from the Sanctuary. The larger
mammals are the blackbuck, spotted deer, wild boar and jackal. The flying fox
resides in large groups on trees in the Point Calimere forest and the mangrove forest
at Muthupet. The blackbuck of Point Calimere represents one of the three isolated
populations of blackbuck existing in Tamil Nadu with the other populations in the
Guindy National Park and near Satyamangalam.
Social & Cultral Values

It provides for local income and employment specially in areas of salt
production, forest produce, firewood and fish products. About 35,000 fishermen and
agriculturists live around the sanctuary.
Threats
Threats to the sanctuary mainly comes from illegal extraction of
–
timber and non timber produce.
There is danger from industrial pollution and poaching.
–
Domestic and industrial saltworks operating in GVS also pose a
–
serious problem.
Conservation Measures
To conserve the blackbuck and other wild animals, an innovative freshwater
source has been created. In the watchtowers, overhead tanks have been
constructed, to supply water during the drought period and underground pipeline is
laid up to 3 kms. to connect the overhead tank for the supply of water. The water
source is from the bore - well equipped with motor. In 1988 a proposal was sent to
the Tamil Nadu Government to extend the area of the Sanctuary to include the Great
Vedaranyam Swamp and the Talaignayar Reserve Forest and rename the sanctuary
as the Point Calimere Wildlife and Bird Sanctuary. The promulgation of this new
sanctuary is still in process.
3.5 Gulf of Mannar
The Gulf of Mannar reefs on the other hand are developed around a chain
of 21 islands that lie along the 140 km stretch between Tuticorin and Rameswaram.
These islands are located between latitude 8O47’ N and 9O15’N and longitude
78O12’E 79O14’
and E. The islands lie at an average of about
8 km from the main land. They are a part of the Mannar Barrier reef, which is about
140 km long and 25 km wide between Pamban and Tuticorin. Different types of reef
forms such as shore, platform, patch and fringing type are also observed in the Gulf
of Mannar. The islands have fringing coral reefs and patch reefs around them.
Narrow fringing reefs are located mostly at a distance of
50 to 100 m from the islands. On the other hand, patch reefs rise from depths of
2 to 9 m and extend to 1 to 2 km in length with width as much as 50 meters. Reef flat

is extensive in almost all the reefs in the Gulf of Mannar. Reef vegetation is richly
distributed on these reefs. The total area occupied by reef and its associated
features is 94.3 sq. km. Reef flat and reef vegetation including algae occupies 64.9
and 13.7 sq. km, respectively. (DOD & SAC, 1997). Visibility is affected by
monsoons, coral mining and high sedimentation load. These reefs are more luxuriant
and richer than the reefs of Palk Bay.
Pillai (1986) provides a comprehensive account of the coral fauna of this
region. There are about 96 species of corals belonging to 36 genera in the Gulf of
Mannar. The most commonly occurring genera of corals are Acropora, Montipora
and Porites. Coral associates such as ornamental fishes belonging to the family
Chaetodontidae, (butterfly fish); Amphiprion sp. (clown fish), Holocentrus sp.
(squirrelfish), Scarus sp. (parrotfish), Lutjanus sp. (snapper fish) and Abudefdul
saxatilis (sergeant Major) are found. Extensive sea grass beds are present; green
turtles, olive ridley turtles and dugongs are dependent on the sea grasses.
The mainland coast of India has the Gulf of Kutch in the Northwest (Gujarat
State) and Palk Bay and the Gulf of Mannar in the southeast (Tamil Nadu State).
Other than these important off shore island groups of India, the Andaman and
Nicobar in the Bay of Bengal and Lakshadweep in the Arabian Sea also have
extensive reef growth. The total area of coral reefs in India is estimated to be 2,374.9
sq. km.
3.6 Issues Related to Coral Reefs
Reef’s resources have traditionally been a major source of food for local
inhabitants and of major economic value in terms of commercial exploitation. Reefs
in India provide economic security to the communities that live alongside them.
There are millions of poor fishers in India whose livelihood depends on coral reefs.
Coral reefs provide up to 25 percent of all the fisheries harvested and 75 percent of
animal protein consumed. Thus, the aspect of coral reefs is significant to the
livelihood and social welfare of communities.
The terms “stress” and “disturbance” have been applied to coral reefs and
many other biological communities, with a variety of interpretations. Stress is a
physiological condition which results from adverse or excessive environmental
factors and in corals this can be measured by decreased growth rates, metabolic

differences and biochemical changes. Disturbance is an ecological phenomenon,
which includes departure from a routine set of conditions.
There are varying levels of degradation which can be observed on coral
reefs, from the extreme and obvious (mortality) to more sublime changes in
characteristics including competitive dominance among organisms, decreased
growth rates, breakdown of organisms association, reduced fecundity, reproductive
failure and declining recruitment of larvae. Essentially, whether a coral reef is killed
in a week, due to sediment burial, or over a ten-year period, due to attrition and lack
of recruitment, the result is the same. The loss of the coral reef community results in
the loss of all the benefits that it offers.
Recent reports indicate that coral reefs are under considerable stress and
are experiencing considerable damage. Coral reefs have been resilient ecosystems
since the Mesozoic (about 200 million years ago), surviving major environmental
events such as ice ages, meteor strikes and large changes in solar activity. Not
withstanding these events, coral reefs have recovered to form the extensive reefs we
see today, although recovery may have taken thousands to hundreds – of thousands
of years. Coral reefs also have the capacity to regenerate rapidly after catastrophic
tropical storms, plagues of the coral-eating Crown-of-thorn starfish, and severe
bleaching. Recovery often takes 15 to 20 years. However, over the past 50 years,
there has been major increase in stresses on coral reefs from direct and indirect
human activities. These stresses are threatening the existence of reefs in some
areas, and will diminish the extent of reefs in other areas.
3.6.1 Natural Stresses to Coral Reefs
The major stresses on reefs are storms and waves, particularly tropical
storms and cyclones. These cause major intermittent damage to reefs, particularly to
those reefs that rarely experience these storms. Cyclone disturbances develop during
certain months (October-November) along the Indian Seacoast and elsewhere in the
tropical region.
These cyclones have sustained winds with speed ranging from 65 to 120 km
per hour. High-speed winds cause extreme wave action that break coral into rubbles
and sometimes large amounts of sand and other materials may be dumped onto the
coral reef. Due to 1969 cyclone a large area of coral was buried under the sand in

Rameswaram area of Gulf of Mannar. Likewise the cyclone of December 1987 in Bay
of Bengal devastated the coral reefs of the Mahatma Gandhi Marine National Park of
Port Blair, Andaman, that resulted in large quantities of broken coral colonies getting
heaped and scattered near the shore.
Freshwater runoff damages reefs in semi-enclosed bays and lagoons (a
channel near the Mahatma Gandhi Marine National Park entrance) by lowering salinity
and depositing large amounts of sediments and nutrients. Reefs are also damaged by
volcanic activity (earthquakes, volcanic lava flows, severe uplifting) in the Andaman
Islands, for example in Barren Island. The major biological stress on reefs is predation
by Crown-of-Thorns starfish and coral diseases have been particularly devastating in
Andaman & Nicobar reefs (Mahatma Gandhi Marine National Park, 1989) and
Lakshadweep respectively. There is now considerable speculation that the incidence
of both these stresses has been exacerbated by human activities.
3.6.2 Impacts of Human Activity on Coral Reefs
Varied man’s activities which are, a cause for concern includes runoff and
sedimentation from development activities (projects), eutrophication from sewage and
agriculture, physical impact from maritime activities, dredging, collecting and
destructive fishing practices, pollution from industrial sources, golf courses and oil
refineries and the synergistic impacts of anthropogenic disturbance on top of natural
disturbance.

3.6.2.1 Sedimentation
Sedimentation, which is the most well studied impact, may affect corals
three different ways: photosynthetically, physically and chemically. As most reef-
building corals obtain the majority of their nutritional requirements through
translocation of metabolites from their photosynthetic partners (Zooxanthellae), any
reduction in the availability of light will affect coral nutrition, growth, reproduction and
depth distribution.
Physically, sediments also interfere with coral nutrition by coating the
feeding surfaces responsible for catching prey items needed to supplement the
energy provided by zooxanthellae. While corals do have the ability to cleanse
themselves using a combination of mucus secretion and ciliary action, chronic
sedimentation may end up in a high energetic cost, adding to the overall impact on
the colony. Sedimentation can alter species composition of reefs through
photosynthetic and physical effects. Change in relative abundance of morphological
types as well as individual species are an important reflection of how sedimentation
as a disturbance affects community structure. The standing examples are the coral
reefs of Gulf of Mannar islands and the reefs of Little Andaman. So far, the presence
of sediment load in the coral reef areas has been confirmed in Gulf of Mannar and
Andaman & Nicobar islands, however, quantitatively they are not reported.
Venkataraman and Rajan (1994) reported the amount of silt carried by the rainwater
from Port Blair City into the sea. Only few studies have been focussed on the effect
of sedimentation and siltation on the damages the reef quantitatively.
Sedimentation can also physically interfere with recruitment of coral larvae,
which require a solid substratum upon which to settle and metamorphose. Dredging
projects have been particularly damaging to reefs, (Sethu Samudram project, Gulf of
Mannar region) primarily through the initial physical disturbance, habitat alteration
and the subsequent problems associated with sedimentation. Sand mining in
Andaman Islands and coral quarrying in Gulf of Mannar (Tuticorin group of Islands)
cause a lot of sedimentation and siltation on coral reefs.
Very few studies have focussed on the chemical effects of sediment on
corals that can be important. Dumping of fly ash near Pandian island at Tuticorin
may contain a variety of heavy metals particularly detrimental to coral reefs.

3.6.2.2 Runoff/Chemical Pollution/ Water Quality
A general rule for coastal zone: whatever is used on land today ends up in
the aquifer or coastal zone tomorrow. Salinity changes alone have proven to affect
corals, especially on shallow water reef flats which are most likely to be affected by
freshwater runoff. The amount of sediments and chemicals the runoff water carries
to the sea has profound effects on fertilization of eggs of coral species. Likewise, the
quality of runoff water can affect the metamorphosis of the larvae of corals. Many
experiments have demonstrated that the actual coastal surface water quality above
reefs during coral spawning events has sufficiently reduced reproductive failure.
Many areas in Andaman & Nicobar islands and Gulf of Mannar area have large
quantities of sediment laden freshwater runoff impinged on coastal reefs, causing
high levels of coral mortality, rapid growth of fleshy algae species, and large areas of
reduced salinity/quality seawater. Local fishermen of Gulf of Mannar have
complained of decreased fisheries and reef vitality not only on these coastal reefs,
but also on off shore islands and reefs not directly affected by contact with the
sediment. Inspection of these reefs revealed (Zoological Survey of India, Chennai)
live adult coral colonies, but no signs of larval recruits with increased levels of
sedimentation.
Oil pollution is an extreme example of how chemicals, in this case
hydrocarbons, can affect reefs. Research performed in many areas have
documented coral mortality, decreased fecundity and recruitment failure in response
to chronic oil pollution.
Industrial waste discharged in to the sea near Tuticorin islands, Chattam
Sawmill wastes in Port Blair are the standing examples of how pollution deteriorates
the reef ecosystem. All the near shore reefs and island reefs of Tuticorin, Gulf of
Mannar and Port Blair area, Andaman & Nicobar area have become barren rocks.

3.6.2.3 Sewage
The overall impact of sewage on a coral reef community depends on
sewage, level of treatment, presence of toxic materials and receiving water
characteristics. The effects of sewage-related nutrient enrichment on coral reef
communities have been documented and include alteration of competitive
interactions, reduction of coral calcification rates from decreased light levels and
increased phosphate concentrations and increased mortality from bacterial infection.
Corals are adapted to live in nutrient poor environments and are relatively slow
growing compared to algae, sponges, tunicates and other groups of sessile benthic
organisms. Nutrients not only increase the bio-mass of phytoplankton, affecting light
transmission and increasing the biological oxygen demand (B.O.D.) which may have
some impact on the corals but also give a competitive advantage to faster growing
benthic species. The green algae has formed large mats, covering and killing corals
in Keelakarai coast coral reefs in Gulf of Mannar due to sewage pollution from the
town. The nutrient enrichment via sewage reduces the photosynthetic efficiency of
corals, as alga cells increase in density to the point of becoming self-shading. Since
the coral zooxanthellae symbiosis evolved under nutrient limited conditions, it is
reasonable to assume that the relationship will become altered in response to
changes in the level of nutrients available. Further studies of the physiological effects
of such changes are needed to determine the sub lethal or long-term effects of
sewage and nutrient enrichment on coral reefs of Gulf of Mannar Islands and
Andaman & Nicobar.
While the effects of suspended solids from sewer out falls have been
compared to those from terrigenous runoff and sedimentation, the two types of
sediment differ in physical, chemical and toxicological characteristics, which must be
considered when assessing impacts. Sewage suspended solids primarily organic,
can contain absorbed toxins, and increase B.O.D more than inorganic sediment
associated with runoff. The toxic component of sewage depends on the sources of
input and is primarily a concern in industrial or agricultural areas where industrial
wastes and pesticides are included in the effluent.

3.6.2.4 Temperature Stress and Bleaching
The negative impacts of increased temperature on corals have been
documented from both anthropogenic and natural sources. There are many
documented evidences for coral mortality associated with the hot water discharge
from a cooling system for a power plant and wide spread mortality with increased
temperatures accompanying the El Nino event. In both cases, the cause of mortality
appeared to be the breakdown of the symbiotic association between the
zooxanthellae and the coral host (bleaching).
There has been unprecedented bleaching of hard and soft corals throughout
the coral reefs of the world from mid-1997 to late-1998. Much of the bleaching
coincided with a large El Nino event followed by a strong La Nina but bleaching in all
the coral reefs is uncorrelated. During this event bleaching and mortality were most
pronounced in shallow water (less than 15 m) and particularly affected staghorn and
plate Acropora and other fast growing corals. Many of the massive, slow-growing
species bleached, but many recovered within one or two months. This bleaching
event has resulted in poor coral cover (recent study by Zoological Survey of India,
Chennai) and possibly fewer new coral recruits on many reefs in India for the next 10
years until recovery gains speed. In the short term, this will affect adversely the
economics of India, particularly fisheries. There will be a shift in the composition of
coral communities; some will have greater dominance of slow growing massive
corals, whereas other reefs will lose century-old colonies. Nevertheless, such shifts
have occurred in the past and are part of the normal variability of many coral reefs. If
however, the recent bleaching event is linked to global climate change, and will be
repeated regularly in the immediate future, the consequences would be serious for
many coral reefs if sea temperatures show a continuing upward trend.
The relationship between bleaching events and ozone depletion/global
warming is presently being studied by several groups of researchers. If the
connection can be proven, it will be an example of global rather than local
anthropogenic impacts on coral reefs.

3.6.2.5 Coral diseases
Four types of coral diseases have been identified : white band disease, black
band disease, bacterial infection, and shutdown reaction. While there is a degree of
uncertainty over the causes responsible for each disease, they all appear to be stress-
related. Synergism is believed to play an important role, as stressed coral seems to be
the most susceptible for the above diseases. Sediment, sewage, pesticides, heavy
metals, bleaching and other human impacts have stressed tumors, bacterial attack
and parasitic worms. White Band disease has been reported from Andaman and
Nicobar and Lakshadweep islands. In addition, a new disease called Pink Line
disease is also reported from Lakshadweep.
3.6.2.6 Destructive fishing practices
The use of destructive fishing practices has been responsible for the
destruction of coral reefs throughout the world. Destructive fishing practices have
seriously damaged many of the Gulf of Mannar’s richest and most diverse coral reefs,
necessitating an urgent warning that immediate and far-reaching action is needed.
The Gulf of Mannar stands out as one of the hardest hit areas, with 60% of its reef in
varying stages of deterioration. Because of the large size of the areas concerned (Gulf
of Mannar and Andaman & Nicobar Islands or other areas in India), and the lack of
general resources for enforcement, education appear to be more successful than
legislation in controlling these practices. Poverty reduces the alternatives for fishermen
who must feed their families and rely on fishing as a source of protein and income.
This same problem has lead to another anthropogenic disturbance on reefs : over
fishing. The use of fish traps made of long-lasting materials with small mesh sizes
results in the capture of pre-reproductive juveniles, affecting future populations and the
death of fish when traps become dislodged during storms, yet continue to capture fish
which eventually starve. Several types of net fishing have also been responsible for
over-exploitation of reef. As with all biological communities in a coral reef, each
species plays an important role in the dynamics of balance. The depletion of grazers,
for example, may eventually lead to an overgrowth of alga as in the case Gulf of
Mannar reefs.
Blast Fishing

Although it is now illegal, blast fishing has been a widespread and accepted
fishing technique in some of the developing countries. Schooling reef fishes are
located visually, after which the capture boat moves within close range and a lighted
bomb is thrown into the middle of the school. After the bomb is exploded, fishermen
enter the water to collect the fish that have been killed or stunned by the resulting
shock wave. Due to blasting, branching, tabulate and foliose hard corals are shattered
while massive and columnar corals are often fractured. Although this effect of blasting
is quite localized, reefs subject to repeated blasting are often to little more than shifting
rubble fields, punctured by the occasional massive coral head. In addition to damaging
the reef framework, blast fishing results in side-kills of non-target and juvenile fishes
and invertebrates.
Trap Fishing- (Koodu)
The use of bamboo mesh traps, locally known as koodu, is wide spread
throughout Gulf of Mannar islands reef fisheries. In Ramanathapuram alone 3312
(37% of the total trap in the Tamil Nadu State) traps are found. Although this gear is
not intrinsically destructive, the process of setting and retrieving the trap is largely
responsible for the destruction wrought on the reef. These traps set by simply lowering
the trap from boat-side via a buoyed rope are responsible for the most reef damage.
The traps are often heavily weighted with wooden runners or stones and can destroy
entire stands of branching and foliose corals on the reef during their installation and
especially removal (by pulling on the rope). If the current trend continues, Koodu trap
activities will become an increasingly important cause of reef damage in Gulf of
Mannar.
Ola valai and Shore Seine
Ola valai is a type of drive-in net fishing technique where by a line of
fishermen in the water use scare-lines, lines with palm leaves tied off at regular
intervals to drive fish down a bag net. The scare lines are rhythmically lifted and
dropped into the shore areas, often breaking live corals while the fish are driven
ahead. Next to this the shore seines form the major gear of Gulf of Mannar. There are
about 1523 numbers of shore seines found in Ramanathapuram district alone, forming
about 33% of the total shore seines in the state. Although this gear is not intrinsically
destructive, the process of shore seines is largely responsible for the destruction of
new colonies emerging near lagoon.

While it is simple to prove how damaging destructive fishing practices are to
the productivity of fisheries, the economic realities of day-to-day life on Gulf of
Mannar and Andaman & Nicobar islands makes the solution difficult to obtain.
3.7 Impacts in Palk Bay and Gulf of Mannar
There are about 47 fishing villages along the coast of which 38 are in the
Ramanathapuram district and nine in V.O. Chidambaranar district bordering the Gulf
of Mannar Park area. Exploitation of fishery resources in the inshore waters has been
the sole occupation of hundreds of fishing families along the coast for centuries. The
reefs are used to carry out reef fishery, chanks and pearl fishery, ornamental shell
trade and illegal mining of corals. The villagers around Palk Bay harvest holothurians,
seahorse and pipe fishes. Other harvesting activities include chanks and milk fish fry.
Turtles are being harvested up to 1000 annually; dugongs are also poached.
The destruction of reefs and reef associated organisms in the Gulf of Mannar
and Palk Bay is perhaps unparalleled in the history of environmental damage to nature
and natural resources in the recent past (Pillai, 1996). The coral reefs on Palk Bay and
Gulf of Mannar were quarried for industrial purposes from early sixties from
Mandapam to Tuticorin. The estimate of coral quarried varies. At Tuticorin the
estimate was 80,000 t per year. Pillai (1973) estimated the exploitation of corals from
Mandapam area during sixties and early seventies to the tune of 250 m3 per day. It is
found that some of the islands (Vilanguchalli in Tuticorin group and Poovarasanpatti
Island in Keelakari group) are totally submerged and vanished because of quarrying. A
recent survey in Palk Bay and Gulf of Mannar has revealed that damage to reef due to
human interference is still rampant. The huge colonies of corals that occupied large
areas in the lagoons of many islands are no more there due to over exploitation of
algae and shells by fishermen in an extensive scale. Fishermen during collection of
algae to negotiate their boats brake most of the corals. The live export of crabs and
lobsters from this area in the recent years is also causing damage to live corals. Fish
traps (Koodu) to collect live crabs are causing a lot of destruction to coral reefs in
these areas. Other than these disturbances, siltation, agricultural run off, sewage
discharge as well as the fecal pollution are the major problems in these areas.
3.8 Conservation

The Federal Government Coastal Regulation Zone Notification 1991
regulates onshore development activities, which affect coastal environments, and
strictly prohibits the collection and trade of corals. Wildlife Protection Act, 1972
provides protection for protected areas and certain marine species. Efforts continue
to bring corals under this act and to encourage enforcement that is more stringent.
Coral reef conservation is also included in the Environmental Protection Act (1986),
the National Conservation Strategy and Policy Statement on Environmental
Development (1992) and the Action Plan of the Ministry of Environment and Forests.
The conservation and management of coral reef resources is within the mandate of
the Ministry of Environment and Forests, the focal point for the Indian Coral Reef
Monitoring Network and the National focal point of ICRI.
India has 6 marine protected areas; the largest is the Gulf of Mannar
Biosphere Reserve (GOMMBRE), which encompasses 10,500 sq km. Coral Reef
Monitoring Action Plans (CRMAPs), prepared under the first phase of the GCRMN,
have been launched within the framework of the ICRMN for all reef areas except the
Gulf of Kutch. Government support has been extended for the implementation of the
CRMAPs and to build capacity to monitor reefs through training. However, activities
are still at a beginning and overall the capacity for monitoring and management is
lacking. Other significant international initiatives on the Indian coral reefs underway
and under development include. UNDP/GEF DPFB projects on the Gulf of Mannar
and Andaman and Nicobar Islands.

3.9 Future Direction
Coral reefs in India are under increasing pressure. In many cases, the
sources of stress due to human pressure are known. However, the etiology of a
growing number of diseases and pathologies now being reported in corals is not
widely understood, highlighting the need for more search to unravel the complex
interactive effects between natural and anthropogenic forms of stress and their effects
on coral reefs. The inability of scientists to predict with any certainty where the critical
thresholds of resilience to stress lie along the continuum of human-induced and
natural disturbances, make it inherently difficult to manage reefs sustainably. Solutions
to these conservation and management problems will need to incorporate effective
science, robust economic analysis and sound policies and laws. Participatory actions
grounded in the cultural and social reality of local people who depend on and benefit
directly from coral reefs must be part of the solution. Creating political will, through
communication and environmental education, will be essential in mobilising and
sustaining conservation efforts.
Studies such as qualitative and quantitative estimation of biodiversity,
percentage cover of live and dead coral estimation by standard methods, estimation of
standing crops of reef resources, their recruitment, growth, mortality, standing stock,
and level of exploitation are necessary to suggest norms for judicious exploitation.
These aspects need intense and long-term study in India. In general, the percentage
cover of live coral estimation is not the only criteria for the health of reefs but also the
ratio of dead and live coverage.
Presence or absence of indicator species may be an index of environmental
stress or pressure on reefs. The taxonomically extended surveys of sessile
organisms such as sponges, alcyonarians and polychaetes can give clue to the state
of art environmental conditions. Assessment of heterotrophic macroinvertebrates
such as sponges, barnacles, hydroides, tunicates, echinoderms etc. may yield clue
to stress conditions due to pollution. Such studies are very important for
management of coral reefs.

3.10 Strategies for Coral Reef Ecosystems in India
3.10.1 Analyzing the Short Comings in Coral Reef
Conservation in India
Recommendations
• Understand the problems facing coral reefs by assembling information from
within India and nearby countries.
• Determine the true economic value of reefs so that rational decisions can be
made on the cost of management.
• Transfer that understanding via education to the principal users, the public
and decision makers.
• Focus management around the user to ensure compliance with and
assistance in resource management.
• Incorporate reefs into marine protected areas to buffer the reefs against
outside damaging influences.
• Control damaging practices and monitor the effectiveness of control.
• Promote sustainable uses to realise the full economic potential of healthy
reefs.
• Monitor the effectiveness of management so that procedures can be
adjusted to ensure long-term sustainability.
3.10.2 Understand The Coral Reef Problems
Recommendations
The coral reef areas in India should be determined using satellite and aerial
images with ground truthing. Assistance may be needed from large agencies such as
the National Aeronautics and Space Application Centre.
• These data should be used to find out the status of the coral reefs and how
they are changing.
• National programmes to monitor the status of coral reefs should be
implemented.

• The knowledge base of scientists, tourists operators, SCUBA divers and
local users should be combined to determine the status of reefs and how
they have changed during living memory.
• Central and State Government may convene national and local committees
including user groups, local government authorities, tourism developers,
scientists and Non governmental organizations (NGOs) to advise on
sustainable management of coral reefs.
3.10.3 Determine the True Economic Value of
Coral Reefs in India
Recommendations
• Direct ‘extractive’ values like fisheries, aquarium fish and other animals,
ornamental products and sand production.
• Potential ‘extractive’ values like pharmaceutical drugs and species
developed for future Mariculture activities.
• Direct ‘non-extractive’ uses such as tourism and educational and research
values.
• ‘Indirect use ‘ values such as the commercial species that migrate to other
areas the physical barrier, role in protecting the shoreline, the value in
extending exclusive economic zone.
• As well as the less tangible ‘non use and aesthetic ‘ values of high
biodiversity habitats for endangered species and roles as part of the global
environment.
• Determination of coral reef fisheries, how these are being exploited (catch
per unit effort) and the dependence by local fishermen on reef fisheries.
• Determination of other values of coral reefs and potential economic losses if
these values are foregone through reef degradation.
• Assessment of the current and potential future income from coral reef
tourism and the contribution of health of reefs towards attracting tourists to
India.
3.10.4 Coral Reef Conservation Education

Recommendations
• Information on the nature and value of coral reefs should be provided to all
users, students and public using appropriate methods. e.g. many fishermen
will not read written material whereas videos and talking are effective.
• Summaries of the status of coral reef resources and sustainable
management methods should be prepared for decision makers and
development agencies, donors and banks.
3.10.5 Focus Management of Coral Reef around the Stakeholder
Recommendations
• National and state governments of India should devolve sufficient
responsibility for the management of coastal resources to local authorities at
the village level.
• Legislation for coastal reef resource management should include the
involvement of the users especially fishermen.
• Developers especially those involved in tourism should consult directly with
local users on resource management and then employ local people to
compensate for restrictions on resource use.
3.10.6 Incorporate More Coral Reefs in Marine Protected Areas
Recommendations
• Large areas of relatively undamaged marine habitat including good coral
reefs should be designated as marine protected areas and management
plans developed to involve all users.
• Assistance for training, planning and management of MPAs should be
requested from international donors, particularly to staff, local authorities
with education officer and MPA Range officers.
• Tourism operators should be involved in the management of MPA and be
prepared to fund some of the management.
3.10.7 Control Managing Practices
Recommendations
Pollution

• Emphasize the treatment of sewage at the source or divert them away from
coral reef onto the land or as deep ocean outfalls.
• New domestic and industrial development should be ‘encouraged’ to treat
sewage as it is cheaper to install sewerage lines and systems during
construction.
• Tourism developments near coral reefs should have full secondary or
tertiary treatment and adequate methods for removing garbage.
• Guidelines should be provided to governments, villagers and developers on
the range of appropriate methods for treating sewage at all scales.
Sedimentation
• Government should request developers and farmers to minimize the amount
of sediment that is lost into rivers and the ocean.
Overfishing
• Fishermen should be discouraged from using destructive methods
(dynamite, cyanide, bleach, poisons) through education, local cooperative
discussion and where possible be provided with other employment.
• Anchor damage should be minimized either by encouraging anchoring on
sandy areas, or with better designed anchors, or through the installation of
permanent mooring buoys for tourist operators in Lakshadweep and
Andaman and Nicobar Islands.
• Remote reefs require special protection through international treaties to
control damaging practices that destroy parent fish stocks and poaching.

3.10.8 Promote Sustainable Uses
Recommendations
• Selective sustainable fishing and harvesting in all the coral reef areas in
India.
• Controlled harvesting or aquarium fish in all the coral reef areas of India.
• Mariculture of reef species for stock enhancement.
• Limited fish cage culture and rack culture of pearl shell edible oyster and
algae.
• Removal of the excess production of sand in coral reef areas especially
Andaman and Nicobar Islands.
• Snorkeling and scuba diving and other tourism activities.
• Advice on sustainable methods of establishing tourism ventures should be
given to developers, which may require government interventions to ensure
that environment departments and universities are involved.
• Reef users require information on sustainable harvesting practices and
assistance to develop markets for those products.
3.10.9 Monitor the Effectiveness of Coral Reef
Management in India
Recommendations
• A committee of experts by the National Coral Reef Committee should
monitor all MPAs and other managed areas in India for the effectiveness of
management particularly to assess whether the health of reefs is stable.
• Inventories of all the coral fauna present in the region and the status of the
coral reefs and the associated fauna are to be monitored on a long-term
basis.
− Increase the capacity of scientists to undertake studies on corals such
as coral taxonomy, biophysical monitoring and database.
− Reduce the risk for coral reef such as destructive fishing practices,
siltation, industrial and domestic sewage and over fishing.

− Developmental projects detrimental to coral reef should be implemented
with caution.
− Alternative employment to coastal fishermen should be provided to
reduce the pressure on the coral reef where the coastal population is
depending on the coral reef.
− Increase the awareness among the local public and made as curriculum
in the schools about the importance of coral reefs.
− Protected areas should be managed properly with modern technology
with the lessons learnt elsewhere.
− Need for central policy decisions to recognise the essential uniqueness
of each of the coral reef areas when creating policy.
− Strengthen the network of coral reef information providers within India
and develop the role of the ICRMN to act as the body to provide
coordination and coherence for policy and programmes relating to coral
reef resources, to provide better integration between government
departments, institutions and local groups and to support the
implementation of Management Action Plans;
− Provide training and awareness raising at all levels to better appreciate
the concepts of conservation and sustainable use of coral reef
resources.
− Artificial reefs should be allowed with more caution and only with EIA
studies.
− More funds to be provided for intensive coral reef research in India
− Collaboration with International agencies on coral reefs should be
encouraged for coral reef conservation.
− NGO’s to be encouraged to educate the coastal population about the
importance of coral reefs in India and their uses.

− Networking of all the stakeholders of coral reef should be made.
− Tourism in coral reef area should not be detrimental to the coral reef
ecosystem and Eco-tourism should be encouraged.
− Establish a separate coral reef research institute in India exclusively for
coral reef studies.

Fig. 3.2 : Variation in Salinity

% %

Fig. 3.4 : Particle Size Distribution of Sediments (1-10 Sampling Stations)

Maximum Diversity Index
0
0.5
1
1.5
2
2.5
3
3.5
4
Sh
in
gl
e
Kr
us
ad
Pu ai
Po lliva
om sa
l
ar
i
M cha
n
an
ol
ip
ut
t
Mi
an
ol
i
M
us
al
M
ul
li
Va
la
i
Ap
Va pa
lim
un
An ai
N aip
al ur
Name of island
la
Pu tha
liv nni
in
i
U cha
l
pp
u t li
h
Fig. 3.6 : Maximum Diversity Index values of
Ka ann
i
ra
ic
Vi ha
la
lli
ng
uc
ha
Ka lli
Phytoplankton in 21 Island of Gulf of Mannar
su
w
ar
Va
n

Maximum Diversity Index
0
0.5
1
1.5
2
2.5
3
3.5
4
Sh
in
gl
e
Kr
us
ad
ai
Pu
Po lliva
om sa
l
ar
ic
M ha
n
an
ol
ip
ut
t
Mi
an
ol
i
M
us
al
M
ul
li
Va
la
i
Ap
Va pa
lim
un
a
An i
N aip
Name of island
al ur
la
Pu tha
liv nni
in
i
U cha
l
pp
ut li
ha
Fig. 3.7 : Maximum Diversity Index values of
Ka nn
i
ra
ic
Vi ha
la lli
ng
uc
ha
Ka lli
Zooplanktons in 21 Island of Gulf of Mannar su
w
ar
Va
n

Fig. 3.8 : Location of Corals in the Gulf of Mannar and the Palk Bay

Maximum diversity Index
Sh
0
0.5
1
1.5
2
2.5
3
in
g
K
ru le
sa
P d
Po ulli ai
om vas
ar a l
M ich
an an
ol
ip
ut
Fig. 3.10 :
M ti
an
o
M li
us
al
M
ul
li
Va
la
Ta i
la
Po iri
ov
A
ar pp
as
an a
Name of island
Va pat
lim ti
un
a
A
na i
N ip
al
l ur
P u a th
liv an
in ni
U ic h
a
pp
ut lli
Maximum Diversity Index values of K han
Corals in 21 Island of Gulf of Mannar
n
ar
Vi aic i
la ha
l
ng
uc li
ha
K
a s lli
uw
ar
Va
n

Maximum Diversity Index
Sh
1.8
1.9
2
2.1
2.2
2.3
2.4
2.5
2.6
in
Kr gle
us
Pu ada
P o lliv i
om as
ar al
M icha
an
ol n
ip
ut
M ti
an
ol
Mi
us
al
M
ul
li
Va
la
Ta i
la
Po iri
ov
ar Ap
as pa
an
Va pat
lim ti
un
An ai
Name of island
N aip
al
la ur
Pu tha
liv nn
i
in
U ich
Fig. 3.15 : Maximum Diversity Index values of
pp al
u t li
h
Ka an
Seagrass in 21 Island of Gulf of Mannar
ra ni
i
Vi
la cha
l
ng
u c li
ha
Ka lli
su
w
ar
Va
n

Maximum Diversity Index
Sh
0
0.5
1
1.5
2
2.5
3
i ng
l
Kr
us e
Pu ada
Po lliv i
om as
ar al
M icha
an
ol n
ip
ut
M ti
an
ol
Mi
us
al
M
ul
li
Va
la
Ta i
la
Po iri
ov Ap
ar
as pa
an
Va pat
lim t i
un
An ai
Name of island
N aip
al
la ur
Pu tha
liv n n
i
in
U ich
pp al
u t li
h
Fig. 3.16 : Maximum Diversity Index values of
K a an
ra n i
i
Vi
la cha
l
ng
uc li
Mangroves in 21 Island of Gulf of Mannar ha
Ka lli
su
w
ar
Va
n

3.92
Maximum Diversity Index
0
0.5
1
1.5
2
2.5
3
Sh
in
gl
e
Kr
us
ad
ai
Pu
lliv
as
Po
al
om
ar
ic
ha
M n
an
ol
ip
ut
ti
M
an
ol
i
M
us
al
M
ul
li
Va
la
i
Ta
la
ir i
Po
Ap
ov
pa
ar
as
an
pa
tti
Va
lim
un
Name of island
ai
An
ai
pu
N r
al
la
th
an
Pu ni
liv
in
ic
ha
U lli
pp
ut
ha
nn
i
Ka
ra
ic
ha
Vi
la lli
ng
uc
ha
and Seagrass in 21 island of Gulf of Mannar
lli
Ka
su
w
ar
Va
n
Fig. 3.18 : Maximum Diversity Index values of Corals, Mangroves
Coral
Seagrass
Mangrove

Fig. 3.1 : Data Locations

3.94
Fig. 3.3 : Variation in Salinity and Silicate
Man
Arthropods
Avifauna Fish Echin
- Crutacea
- Aquatic 441 Species 264 S
368 Species
Bacteria and
Mammals Annellids
Avifau Arthropods Mollusca Coelenterat
Funji
11 Species - Polychata
721 Species Coral –128
75 Species
Gorgonids -
3.96

Fig. 3.5 : Trophic Relations of Marine Ecosystem in study area of Sethu
Samudram Ship Canal Project

3.100
Fig. 3.9 : Coral Reef and Seagrass Areas around the Islands of Gulf of Mannar

3.102
Fig. 3.11 : Locations of Pearl Banks in the Gulf of Mannar
3.103

Fig. 3.12 : Chank Habitats in the Gulf of Mannar and the Palk Bay

3.104
Dugong dugong Ha
GULF OF MANNAR
Fig. 3.13 : Habitats of Sea Cow (Dugong-dugong) in the Gulf of Mannar and the Palk
Bay

3.105
Fig. 3.14 : Habitats of Sea Weed, Sea Grass and Holothuria in the Gulf of Mannar and
the Palk Bay
3.108

Mangroves
Fig. 3.17 : Locations of Mangroves in Gulf of Mannar and the Palk Bay
Table 3.2
Physico-Chemical Quality of Marine Water
Location
Sr. Palk Bay Gulf of Mannar
Parameter Sample
No.
1 2 3 4 5 6 7
32.8 32.4 32.0 32.6 32.4 32.3 32.1
Surface
Temperature (oC)
1.
Bottom 32.2 31.9 32.0 32.3 32.5 32.4 31.8
2. 2.8 4.0 4.9 3.4 3.4 2.8 3.2
Surface
Turbidity (NTU)
3.111
Bottom 3.2 4.3 4.3 3.5 3.6 2.5 6.0
8.0 8.1 8.0 8.0 8.2 8.2 8.2
Surface
3. pH
Bottom 8.0 8.0 8.0 8.0 8.2 8.2 8.2
51.4 52.1 59.3 50.0 59.3 59.7 60.2
Surface
Conductivity
4.
(mS/cm) Bottom 52.2 49.9 59.5 52.3 59.4 59.8 60.0
33.4 34.4 39.7 32.8 39.7 40.0 40.4
Surface
Salinity (o/oo)
5.
Bottom 34.7 32.2 39.9 34.5 39.9 40.1 40.3
33.2 33.4 37.9 32.0 37.9 38.2 38.5
6. TDS (gm/L) Surface

Bottom 33.7 31.4 38.1 33.4 38.1 38.3 38.4
5.4 5.6 4.5 4.8 4.1 3.6 4.2
Surface
7. DO (mg/L)
Bottom 5.1 4.6 4.4 4.9 4.2 4.1 4.2

Table 3.4
Sediment Quality
Location
Sr.
Parameter Palk Bay Gulf of Mannar
No.
1 2 3 4 5 6 7
1. pH 7.6 7.4 8.2 8.0 7.9 7.8 8.2
2. Moisture 71.46 72.63 74.51 72.05 71.72 72.02 76.62
3. Ash 27.72 26.50 25.07 27.59 27.62 27.41 21.91
4. Volatile Solids 0.82 0.87 0.42 0.36 0.66 0.57 1.47
3.113
5. Total Organic Carbon (C) 0.4 0.4 0.2 0.2 0.2 0.1 0.13
6. Total Phosphorus (P2O5) BDL BDL 0.02 0.84 0.015 0.02 BDL
7. Total Kjeldhal Nitrogen (N) 0.14 0.13 0.08 0.05 0.06 0.05 0.09
8. Chloride (C) 1.25 1.63 2.05 3.15 3.1 4.9 4.25
9. Sulfate (SO4) 0.68 0.65 0.06 0.2 0.08 0.4 0.18
10. Sodium (Na) 2.88 3.8 0.4 0.7 1.6 0.9 1.44
11. Potassium (K) 0.66 0.72 0.04 0.07 0.06 0.07 0.08
12. Iron (Fe) 3.04 3.5 0.40 0.36 0.356 0.254 0.528
13. Manganese (Mn) 0.27 0.32 0.005 0.012 0.003 0.013 0.012
14. Copper (Cu) 0.002 0.004 0.001 0.003 0.007 BDL 0.002 0
15. Zinc (Zn) 0.009 0.01 BDL 0.002 0.01 BDL 0.004

Table 3.4 (Contd…)
Location
Sr.
Parameter Palk Bay Gulf of Mannar
No.
1 2 3 4 5 6 7
16. Arsenic (As) 0.033 0.041 0.006 0.006 0.005 0.004 0.007
17. Chromium (Cr) 0.007 0.008 0.001 0.001 BDL BDL 0.001
18. Lead (Pb) 0.004 0.005 0.001 0.001 0.001 0.001 0.001
19. Nickel (Ni) 0.004 0.005 0.001 BDL BDL BDL 0.001
20. Selenium (Se) 0.005 0.006 0.001 0.001 0.001 0.001 0.002
3.114
21. Cadmium (Cd) 0.001 0.001 BDL BDL BDL BDL BDL
22. Boron (B) 0.023 0.028 0.002 0.002 0.002 0.001 0.003
23. Cobalt (Co) 0.001 0.002 BDL BDL BDL BDL BDL
24. Calcium (Ca) 5.675 5.662 6.500 6.5 7.3 8.24 7.50
25. Magnesium (Mg) 1.86 3.30 2.04 3.16 3.832 3.12 4.24
26. Oil and Grease 0.07 0.11 0.24 0.15 0.12 0.09 0.08
BDL : Below Detectable Limit
All values are expressed in g/100 g dry wt. Except pH

Table 3.14
Enumeration and Diversity of Zooplankton
Sampling Percent Organisms in Group
Total Zoo-
Station
plankton
Cteno- Cnid- Poly- Clado- Cope- Deca- Ptero- Moll- Chaeto- Appen
(no. m-3)
phora aria chaeta cera poda poda poda usca gnatha icular
1 1649 - 0.73 0.61 0.18 63.67 15.77 0.73 0.91 1.82 0.12
2 1531 0.13 1.31 0.98 0.33 65.38 17.64 0.65 0.52 2.61 -
3 1459 0.55 1.23 1.37 0.21 69.77 8.50 0.55 0.69 1.37 -
3.130
4 1177 0.51 0.85 1.70 - 66.86 10.21 0.85 0.51 1.27 0.25
5 972 0.51 2.06 3.09 - 71.92 8.23 1.03 0.82 1.03 0.51
6 1233 0.24 1.22 1.62 - 73.56 12.17 0.65 0.81 2.03 0.41
7 1370 1.31 0.58 1.46 0.15 66.72 18.25 0.73 0.22 2.19 0.36
8 787 1.90 1.27 3.18 - 5.57 16.52 2.54 0.64 2.54 0.51
9 1116 1.79 1.34 4.03 0.18 62.19 17.03 0.45 1.34 0.72 0.18
10 1273 1.18 1.18 3.39 0.31 64.40 18.07 0.24 1.96 0.79 0.08

Table 3.18
Enumeration and Diversity of Macrobenthos
Sampling Total Percent Organisms in Group
Station Macro-
benthos Chloro- Phaeo- Sperm- Pori- Alcyo- Sclera- Poly- Brach- Gastro- Biv
phyceae phyceae tophyta fera nacea naeta chaeta yara poda vi
1 8 - - - 37.50 50.00 12.50 - - - -
2 2 - - - - - 50.00 - - - 50.0
3 44 25.00 4.55 20.45 - - - - - 22.73 11.3
3.134
4 18 - - - - - - - - - 55.
5 23 - - - - - - - 13.04 - 86.9
6 5 - - - - - - 80.00 - - 20.0
9 67 7.46 - - 31.34 - - - - 5.97 25.3
10 8 - - - 37.50 - - - - - 12.
Note : Data is not available for 7 & 8 locations due to poor visibility
Table 3.1
Particulars of Sampling Locations along the
Proposed Canal Alignment
Depth
Station Latitude Longitude
(m)
Palk Bay
9o 27’ 14 ”N 79o 27’ 00” E
1 16
9o 21’ 26 ”N 79o 27’ 37” E
2 16
9o 13’ 42 ”N 79o 28’ 57” E
3 10
9o 10’ 58 ”N 79o 27’ 17” E
4 7
Gulf of Mannar
9o 09’ 04 ”N 79O 26’ 16” E
5 3
9o 08’ 43 ”N 79O 25’ 35” E
6 7
9o 07’ 08”N 79O 19’ 07” E
7 14

9o 03’ 38 ”N 79O 11’ 30” E
8 23
Tuticorin Port Area
8o 45’ 44” N 78O 17’ 52” E
9 23
8o 47’ 09” N 78O 20’ 01” E
10 21

Table 3.3
Marine Water Quality
(Inorganic, Nutrient and Heavy Metals)
Location
Sr.
Parameter
No. 2 4 6 8 10
1. Total Alkalinity (as CaCO3) 104 104 104 106 106
2. Nitrate Nitrogen (as N) 0.87 0.83 0.83 0.93 0.78
3. Chloride (as Cl) 20080 19580 19580 20580 20080
4. Total Phosphate (as P) 0.02 0.01 0.03 0.02 0.03
5. Silicate (as SiO2) 0.013 0.008 0.005 0.004 0.003
Heavy Metals
6. Arsenic (as As) ND ND ND 0.02 0.13
7. Selenium (as Se) ND ND ND ND ND
8. Chromium (as Cr) ND ND ND ND ND
9. Zinc (mg/L, Zn) ND ND ND ND ND
10. Lead (as Pb) ND ND ND ND ND
11. Cadmium (as Cd) ND ND ND ND ND
12. Nickel (as Ni) ND ND ND ND ND
13. Boron (as B) 2.96 2.91 2.74 2.70 2.38
14. Manganese (as Mn) ND ND ND ND ND
15. Iron (as Fe) ND ND 0.03 0.08 ND
16. Copper (as Cu) ND ND ND ND ND
ND : Not Detectable
All values are expressed as mg/L

Table 3.5
Gross Primary Productivity
Position Productivity
Location
mgC/m3/day
Latitude Longitude
Palk Bay
9O 27’ 14” N 79o 27’ 00” E
1 269
9O 21’ 26” N 79o 27’ 37” E
2 240
9O 13’ 42” N 79o 28’ 57” E
3 154
9O 10’ 58” N 79o 27’ 17” E
4 148
Gulf of Mannar
9o 09’ 04” N 79o 26’ 16” E
5 210
9o 08’ 43” N 79o 25’ 35” E
6 210
9o 07’ 08” N 79o 19’ 07” E
7 180
9o 03’ 38” N 79o 11’ 30” E
8 257
9o 14’ 04” N 79o 14’ 19” E
11* 128
9o 11’ 18” N 79o 12’ 36” E
12* 472
9o 11’ 03” N 79o 08’ 47” E
13* 194
Tuticorin Port Area
9o 45’ 44” N 79o 17’ 52” E
9 267
9o 47’ 09” N 79o 20’ 01” E
10 126
* Locations near Marine National Park

Table 3.6
Number of Species Recorded in the Gulf of
Mannar Marine Biosphere Reserve during Different Periods
No. of Species recorded during
Groups
1903-1986* 1993-1997*
Chlorophyceae 32
Pheaphyceae 35
Rodophyceae 59
Cyanophyceae 3
Sea grass 13
Foraminifera 51(2)
Tintinida 12
Sponges 275(31)
Coelenterata (non-coral) 123 (48) 27
Corals 128 (42) 21
Polyzoa 100(15)
Polychaeta 75(22) 6
Copepoda 223(63)
Cumacea 10(9)
Amphipoda 52 (28)
Ostracoda 57(23)
Isopoda 18(9)
Lobster 5 3
Prawns 41(4) 24
Leptostraca 1
Schizopoda 1
Mysidae 1
Squillidae 25(2)
Anomura 38(1)
Brachyura 172 (13) 95
Mollusca 731 (23) 75
Chaetognatha - 17
Echiompdemata 264 (2) 116
Hemichordata 1 (1) 2
cephalochordata 6 (1) 2
Urochordata 59 (38) 79
Fishes 580 581
Turtles 5 6
Birds 61
Mammals 11 6
Totals Species 3268 1050
Figures in parenthesis indicate number of endemic species
* Complied by CMFRI, Kochi from studies carried out by different authors (refer
list of references)
# Based on survey undertaken by ZSI (Anonymous 1998)

Table 3.7
Status Report of Biota of Gulf of Mannar
Sr. Species Common Rare Endangered Endemic Commercially Scientific
No. Threatened Collections
(C) (R) (End) (En) (CT) (SC)
Phylum : Protozoa
Class : Forminifera
Trochammina
1. X
inflata
Robulus limbosus
2. X
Nonionia scapha
3. X
Operculina
4. X
gaimairdi
Bulimina elegans
5. X
Bolivinia
6. X
rhomboidalis
Bolivinia robusta
7. X
Bolivinia
8. X
subrenlusts
Streblus
9. X
catesbyarus
Poroeponides
10. X
lateralis
Cancris auriculus
11. X
Phylum : Porifera
Class : Desmosponglae
12. Heteronema oracta X
Spongta officinatis
13. X
Dysidea fragilis
14. X

Sr. Species Common Rare Endangered Endemic Commercially Scientific
No. Threatened Collections
(C) (R) (End) (En) (CT) (SC)
Haliclona exigua
15. X
Callyspongia
16. X
fibrosa
Callyspongia difusa
17. X
Spirastrella
18. X
coccinea
Spirastrella
19. X
cuspidifera
Cliona carpenteri
20. X
Cliona orientalis
21. X
Cliona vastifica
22. X
Ecionemia acervus
23. X
Myriastra purpurea
24. X
Paratettlla baca
25. X
Dercitopsis
26. X
ceylonica
Dercitopsis minor
27. X
Pellona ditchela
28. X
Phylum : Coelenterata
Class : Anthozoa
Order : Scleractinla
29. Psammacora X
contigua
Pocillopora
30. X
damicomis

Sr. Species Common Rare Endangered Endemic Commercially Scientific
No. Threatened Collections
(C) (R) (End) (En) (CT) (SC)
Pocillopora danae
31. X
Acropora
32. X X
corymbosa
Acropora Formosa
33. X
Acropora nobills
34. X
Acropora
35. X
multicaulis
Acropora surculosa
36. X
Acropora lnimilis
37. X
Acropora crythraea
38. X
Montipora
39. X
granulose
Montipora digitata
40. X
Montipora
41. X
divaricata
Montipora
42. X
turgescens
Montipora verrtilli
43. X
Montipora foliosa
44. X
Pavona decussata
45. X
Coscinaraea monile
46. X
Goniopora
47. X
duofaciata
Goniopora nigra
48. X

Sr. Species Common Rare Endangered Endemic Commercially Scientific
No. Threatened Collections
(C) (R) (End) (En) (CT) (SC)
Porites
49. X
mannarensis
Porites solida
50. X
Porites lutea
51. X X
Porites somaliensis
52. X
Porites lichen
53. X
Favia favus
54. X X
Favia
55. X
valenctennesii
Favia pallida
56. X
Favites abdiata
57. X
Favites pentagona
58. X
Goniastrea
59. X
retiformis
Goniastrea
60. X
pactinata
Platygyra lamellina
61. X
Leptastrea
62. X
transvera
Echinopora
63. X
lamellose
Galaxea fascicularis
64. X
Symphyllia recta
65. X
Turbinaria peltata
66. X X

Sr. Species Common Rare Endangered Endemic Commercially Scientific
No. Threatened Collections
(C) (R) (End) (En) (CT) (SC)
Class : Hydrozoa
Halammohydra
67. X
octopodides
Phylum : Annelida
Class : Polychaeta
68. Aphrogenia alba X
Photogenia indica
69.
Harmothoe minuta
70. X
Iphione muricata
71. X
Chloeia rosea
72. X
Eurythoe
73. X
complanata
Syllis (Syllis) gracilis
74. X
Ceratonereis
75. X
mirabilis
Perinereis cultrifera
76. X
Perinereis nuntia
77. X
Eunice antennata
78. X
Eunice (Palolo)
79. X
siciliensis
Marphysa corallina
80.
Onuphis (Nothria)
81. X
conchylega
Malacoceros
82. X
indicus

Sr. Species Common Rare Endangered Endemic Commercially Scientific
No. Threatened Collections
(C) (R) (End) (En) (CT) (SC)
Armandial
83. X
lanceolata
Axiothella
84. X
obockensis
Nicolea
85. X
gracilibranchis
Hypsicomus
86. X
phaeotaenia
Class : Sipunculida
Phascolosoma
87. X
nigrescens
Phascolosoma
88. X
scolops
Phascolosoma
89. X
stephensoni
Class : Echiura
Thalassema
90. X
diaphanes
Phylum : Platyhelminthes
Class : Turbellaria
91. Acanthomacrostom X
um gerlachi
Octoplana
92. X
subterranean
Phylum : Nematoda
Class : Aphasmidea
93. Anticoma X

Sr. Species Common Rare Endangered Endemic Commercially Scientific
No. Threatened Collections
(C) (R) (End) (En) (CT) (SC)
acuminata
Halalaimus
94. X
supercirrhatus
Oncholaimus
95. X
brachycerus
Chromadora
96. X
vulgaris
Halichoanolaimus
97. X
robustus
Latronema orcimum
98. X
Metachromadora
99. X
clavata
Desmodora
100. X
brevicclis
Camacolaimus
101. X
prytherchi
Phylum : Arthropoda
Class : Crustacea
102. Penaetus X
semisulcatus
Penaeus indicus
103. X
Alpheus frontalis
104. X
Alpheus
105. X
macrocelas
Pontophilus
106. X
candidus

Sr. Species Common Rare Endangered Endemic Commercially Scientific
No. Threatened Collections
(C) (R) (End) (En) (CT) (SC)
Pontophilus incisus
107. X
Corallicaris
108. X
gramines
Leptocarpus
109. X
potamuscus
Perclimenes
110. X
(Harpilius) agag
Perclimenes
111. X
(Perclimenes)
digitalis
Perclimenes
112. X
(Perclimenes) impar
Anomura
Clibanarius
113. X
longitarus
Clibanarius
114. X
merguiensis
Diogenes
115. X
investigators
Pagurus megistos
116. X
Brachyuran Crabs
117. Dromia dehaani X
Portunus (Portunus)
118. X
pelagicus
Portunus (Portunus)
119. X

Sr. Species Common Rare Endangered Endemic Commercially Scientific
No. Threatened Collections
(C) (R) (End) (En) (CT) (SC)
sanguinolentus
Scylla serrata
120. X
Thalamita crenata
121. X
Thalamita prymna
122. X
Charybdis
123. X
(Charybdis)
anmulata
Charybdis
124. X
(Charybdis)
anisodon
Trapezia areolata
125. X
Trapezia cymodoce
126. X
Trapezia ferruginea
127. X
Halimede ochtodes
128. X
Atergatis floridus
129. X
Etisus laevimarus
130. X
Chlorodiella nigra
131. X
Cymo andreossyi
132. X
Pseudoliomera
133. X
speciosa
Composcia retusa
134. X
Phalangipus hystrix
135. X
Schizophrys aspera
136. X
Doclea canalifera
137. X

Sr. Species Common Rare Endangered Endemic Commercially Scientific
No. Threatened Collections
(C) (R) (End) (En) (CT) (SC)
Myra fugax
138. X
Philyra syndactyla
139. X
Leucosia anatum
140. X
Matuta lunaris
141. X
Matuta miersi
142. X
Grapsus
143. X
albolineatus
Percnon
144. X
planissimum
Phylum : Mollusca
Class : Crustacea
Order : Stomatopoda
145. Gonadactylus X
chiragra
Gonadactylus
146. X
falcatus
Heterosquilla jonest
147. X
Brachyuran Crabs
148. Cellana radiata X
Trochus radiatus
149. X
Angaria plicata
150. X
Turbo intercostalis
151. X
Lambis lambis
152. X
Cypraea moneta
153. X
Cypraea tigiris
154. X
Fucus ficus
155. X

Sr. Species Common Rare Endangered Endemic Commercially Scientific
No. Threatened Collections
(C) (R) (End) (En) (CT) (SC)
Chicoreus
156. X
virgeneus
Chicoreus ramosus
157. X
Babylonia spirata
158. X
Hemifusus
159. X
pugilimus
Xancus pyrum
160. X
Conus araneosus
161. X
Conus fugilimus
162. X
Class : Bivalvia
Arca inaequivalis
163. X
Arca fusa
164. X
Modiolus sp.
165.
Lithophaga nigra
166. X
Lithophaga gracilis
167. X
Pernna viridis
168. X
Pinna vexillum
169. X
Pinna bicolor
170. X
Placenta placenta
171. X
Ostrea forskalii
172. X
Cardium assimile
173. X
Class : Cephalopoda
Sepia aculeate
174. X
Sepia pharaonis
175. X

Sr. Species Common Rare Endangered Endemic Commercially Scientific
No. Threatened Collections
(C) (R) (End) (En) (CT) (SC)
Sepia kobiensis
176. X
Sepia brevimana
177. X
Logigo duvauceli
178. X
Octopus rugosus
179. X
Octopus macropus
180. X
Phylum : Echinodermata
Class : Asteroidea
181. Culcita X
novaeguineae
Pentaceraster
182. X X
regubus
Dactylosaster
183. X
cylindericus
Disasterinaleptalac
184. X
antha
Class : Ophiuroidea
Ophiomyza
185. X
australis
Ophiactis savgnyi
186. X
Ophiothrix
187. X
(Keystonea)
nereidina
Ophiocoma
188. X
erinaceus
Class : Echinoidea
Diadema savignyi
189. X

Sr. Species Common Rare Endangered Endemic Commercially Scientific
No. Threatened Collections
(C) (R) (End) (En) (CT) (SC)
Echinothrix
190. X
diadema
Echinometra
191. X
mathaei
Class : Holothuroidea
Holothuria
192. X
(Halodeima) atra
Holothuria
193. X
(Haloteima) edulis
H. (Lessonothuria)
194. X
pardalis
Holothuria
195. X X
(Metriatyla) scabra
Holothuria
196. X
(Thymiosycia) hilla
Phylum : Hemichordara
Class : Enteropneusta
197. Ptychodera flauva X

Table 3.8
Distribution of Phytoplankton in Gulf of Mannar
(Number of Species Recorded During October ’98, August ’99)
Sr. Island Bacillario Dino Cyano Chloro Total
No. Phyceae Phyceae Phyceae Phyceae
1 Shingle 16 3 0 1 20
2 Krusadai 19 3 1 1 24
3 Pullivasal 21 2 1 0 24
4 Poomarichan 22 2 2 0 26
5 Manoliputti 22 4 0 0 26
6 Manoli 13 1 0 1 15
7 Musal 22 2 2 0 26
8 Mulli 21 3 0 0 24
9 Valai 11 3 1 0 15
10 Appa 26 2 1 2 31
11 Valimunai 21 1 1 0 23
12 Anaipur 17 1 0 0 18
13 Nallathanni 28 4 2 1 35
14 Pulivinichalli 21 4 0 0 25
15 Upputhanni 19 5 0 0 24
16 Karaichalli 18 3 2 0 23
17 Vilanguchalli 18 2 0 0 20
18 Kasuwar 30 4 2 0 36
19 Van 27 3 1 1 32
Source : Resources information system for Gulf of Mannar (India), GOI, DOD,
Integrated Coastal and Marine Area Management Project Directorate,
Chennai, April 2001

Table 3.9
Maximum Diversity Index Values of Phytoplankton
in 21 Islands of Gulf of Mannar
Sr. No. Name of island Maximum diversity index
1 Shingle 2.996
2 Krusadai 3.178
3 Pullivasal 3.178
4 Poomarichan 3.258
5 Manoliputti 3.258
6 Manoli 2.708
7 Musal 3.258
8 Mulli 3.178
9 Valai 2.708
10 Appa 3.434
11 Valimunai 3.135
12 Anaipur 2.89
13 Nallathanni 3.555
14 Pulivinichalli 3.218
15 Upputhanni 3.178
16 Karaichalli 3.135
17 Vilanguchalli 2.996
18 Kasuwar 3.583
19 Van 3.465
Formula : Maximum Diversity Index (MD) = log2 (TT)
Where TT is total taxa
Source: Evaluation of Fourteen Trophic State Indices for Phytoplankton of
Indian Lakes and Reservoirs
Environmental Pollution (Series A) 27 : 143-153
Editor : Sullivan P.I and Carpenter S.R (1982)
The data of Poovaransapatti and Talairi island is not available

Table 3.10
Enumeration and Diversity of Phytoplankton
Shannon
Percent organisms in group
Total
Wiener
Location Phytoplankton
Diversity
Cyano- Bacillario- Dino-
(No.m3)
Index
phyceae phyceae phyceae
1 801300 99.84 0.07 0.09 0.03
2 121100 99.09 0.50 0.41 0.14
3 35400 98.87 0.85 0.28 0.12
4 120200 99.83 0.14 0.03 0.03
5 144300 99.79 0.21 - 0.02
6 130670 99.87 0.10 0.03 0.02
7 90320 99.64 0.18 0.18 0.40
8 220 - 59.10 40.90 2.59
9 250 - 40.00 60.00 2.28
10 400 - 37.50 62.50 2.13

Table 3.11
List of Phytoplankton Recorded
Sr. Station
1 2 3 4 5 6 7 8 9 10
No. Name of Alga
Cyanophyceae
1. Trichodesmium + + + + + + + - - -
Theibautii
Bacillariophyceae
2. Rhizosolenia sp. + + - + + + + + + +
3. Coscinodiscus sp. - + + + - + - + + +
4. Biddulphia sp. - - - - - + + + - -
5. Pleurosigma sp. + - - - - - - - - -
6. Bacteriastrum - - - - - - + + + -
hyalinum
7. Gunieardia sp. + - - - - - - - - -
8. Thallasiothrix sp. - + + + - - + + + +
9. Chaetoceros sp. - - + + - + - - - -
Dianophyceae
10. Peridinium sp. + + - - - + + + + -
Ceratium sp.
11. + + + + - + + + + +
12. Dianophysis caudata + + - - - - + + + +
13. Diplosalis lenticulata + + + - - - - - - -
14. Triceracium sp. - - - - - - + + - +

Table 3.12
Distribution of Zooplankton in Gulf of Mannar
(Number of Species Recorded During October ’98, August ’99)
Island Hydrozoa Total
Sr. Granuloret Polyhymeno Poly- Crus- Sagi- Thali-
No. Iculosa phora chaeta tacea ttoidea acea
1 Shingle 1 - 2 1 17 2 1 24
2 Krusadai - 1 1 - 18 - 1 21
3 Pullivasal - 1 - - 17 1 - 19
4 Poomarichan 1 - 1 1 24 - 1 28
5 Manoliputti 1 - 2 - 12 1 1 17
6 Manoli 1 - 1 - 19 1 - 22
7 Musal - 1 1 1 19 - 1 23
8 Mulli - 1 - 1 14 - - 16
9 Valai 1 - - 2 15 - 1 19
10 Appa 1 - 1 1 21 1 - 25
11 Valimunai - - - - 18 - 1 19
12 Anaipur - - - 1 18 - - 19
13 Nallathanni 1 - - - 17 2 - 20
14 Pulivinichalli 1 1 - 1 19 - - 22
15 Upputhanni - 1 1 - 18 1 1 22
16 Karaichalli - - 1 1 20 - - 22
17 Vilanguchalli - - 2 - 18 1 1 22
18 Kasuwar - - 1 1 24 - - 26
19 Van 1 1 1 1 31 - 1 36
Source : Resources information system for Gulf of Mannar (India), GOI, DOD,
Integrated Coastal and Marine Area Management Project Directorate,
Chennai, April 2001

Table 3.13
Shannon Weaver Diversity Indice of Zooplankton Recorded
at various Coastal Waters in India
Area Year Diversity indices
Bombay High 1989 0.5-4.04
Bombay Bassein 1989 1.21-3.93
Heera ratna 1989 0.72-3.89
Tapti 1989 2.23-3.47
Surat 1997 1.00-2.55
Jamnagar 1992 0.48-2.80
Sursanyam 1989 1.50-2.04
Kaveri basin 1989 1.00-3.72
Godavari basin 1989 1.69-3.42
Manglore 1988 1.07-1.45
Gandhar 1991 0.70-2.16
Gopalpur 1996 1.8-3.4
kavaratti 1997 0.97-3.26
Agatti 1997 1.38-3.74
Kolaba 1991 1.00-3.09
Worli 1991 0.92-3.25
Kashid Bay 1991 0.95-2.76
Muttukadu (near Chennai) 1995 1.80-3.08
Palk Bay (present study) 1998 2.94-4.24
Gulf of Mannar (present study) 1998 2.36-3.68
Source : NEERI, Nagpur and CMFRI, Kochi

Table 3.15
List of Zoolplankton at Different Locations
Sr.
Name 1 2 3 4 5 6 7 8 9 10
No.
Cnidaria
+ + + + +
1. Medusae + + + + +
Ctenophora
+ + + + +
2. Beroe sp. - + + + +
Chaetognatha
+ + + + +
3. + + + + +
Unidentified
Polychaeta
+ + + + +
4. Polychaete larvae + + + + +
Pteropoda
+ + + + +
5. Unitentified + + + + +
Mollusca
+ + + + +
6. Molluscan larvae + + + + +
Cladocera
- + - + +
7. Evadne sp. + + + - -
- + - + +
8. Penilia sp. + - - - -
Copepoda
+ + + + +
9. Acartia sp. + + + + +
+ + + + +
10. Tortanus sp. + + + + +
+ + + + +
11. Calanopia sp. + + + + +
+ + + + +
12. Centropages sp. + + + + +
- + + + +
Pontella sp.
13. + + + + +
+ + + + +
14. Paracalanus sp. + + + + +
+ + + + +
15. Canthocalanus sp. + + + + +
+ + + + +
16. Eucalanus sp. + + + + +
+ + + + -
17. Metis sp. + + - + +
+ + + - +
18. Oithona sp. - + + - +
Decapoda
+ + + + +
19. Lucifer sp. + + + + +
+ + + + +
20. Decapod larvae + + + + +
Appendicularia
+ + + + +
21. Oikopleura sp. + - - + +
Pisces
+ + + + +
22. Fish eggs and larvae + + + + +
+ + + + +
23. Others + + + + +

Table 3.16
Maximum diversity index values of Zooplankton
in 21 islands of Gulf of Mannar
Sr. No. Name of island Maximum diversity index
1 Shingle 3.178
2 Krusadai 3.044
3 Pullivasal 2.944
4 Poomarichan 3.332
5 Manoliputti 2.833
6 Manoli 3.09
7 Musal 3.135
8 Mulli 2.772
9 Valai 2.944
10 Appa 3.218
11 Valimunai 2.944
12 Anaipur 2.944
13 Nallathanni 2.995
14 Pulivinichalli 3.091
15 Upputhanni 3.091
16 Karaichalli 2.3026
17 Vilanguchalli 3.091
18 Kasuwar 3.258
19 Van 3.583
Formula : Maximum Diversity Index (MD) = log2 (TT)
Where TT is total taxa
Source : Evaluation of Fourteen Trophic State Indices for
Phytoplankton of Indian
Lakes and Reservoirs
Environmental Pollution (Series A) 27 : 143-153
: Sullivan P.I and Carpenter S.R (1982)
Editor
The data of Poovaransapatti and Talairi island is not
available

Table 3.17
Distribution of Benthic Organisms in Gulf of Mannar
Sr. Island
No.
Platyhelminthes
Echinodermata
Hemichordata
Arthropoda
Nemotoda
Sipuncula
Conidaria
Protozoa
Mollusca
Annelida
Porifera
Echiura
Total
1 Shingle 7 5 14 13 - 2 2 8 25 16 4 - 96
2 Krusadai 10 6 19 12 - 3 1 7 26 18 8 1 111
3 Pullivasal 5 3 16 8 - 1 1 4 14 6 5 0 63
4 Poomarichan 4 5 13 15 - 3 1 8 21 11 1 - 81
5 Manoliputti 7 8 13 12 - 2 1 9 28 19 7 - 106
6 Manoli 7 11 26 16 1 3 2 8 31 21 13 - 139
7 Musal 10 7 30 18 1 3 2 8 37 26 11 - 153
8 Mulli - - 18 - - - - - 7 4 - - 29
9 Valai - - 11 - - - - - 6 3 1 - 21
10 Talairi - 1 15 - - - - - 8 3 3 - 30
11 Appa - - 11 - - - - - 10 4 1 - 26
12 Poovarasanpatti - - 11 - - - - - 2 - 1 - 14
13 Valimunai - 1 12 1 - - - - 7 5 1 - 27
14 Anaipur - 1 22 1 - - - - 9 4 2 - 39
15 Nallathanni - - 23 - - - - - 8 6 2 - 39
16 Pulivinichalli - 1 7 - - - - - 1 - 1 - 10
17 Upputhanni - - 17 - - - - - 2 3 2 - 24
18 Karaichalli - - 26 - - - - - - 3 1 - 30
19 Vilanguchalli - - 9 - - - - - 2 1 1 - 13
20 Kasuwar - 1 15 - - - - - 2 2 2 - 22
21 Van - - 15 - - - - - 1 1 1 - 18
Source : Resources Information System for Gulf of Mannar (India), GOI, DOD and Integrated
Coastal and Marine Area Management Project Directorate, Chennai, April 2001

Table 3.19
List of Macrobenthos Recorded
Sr.
Name 1 2 3 4 5 6 7 9 10
No.
Chlorophyceae
1. Halimeda sp. - - + - - - + - -
2. Caulerpa sp. - - + - - - - + -
3. Ulva sp. - - - - - - - - -
4. Enteromorpha sp. - - - - - - - - -
5. Codium sp. - - + - - - - - -
Phaeophyceae
6. Padina sp. - - - - - - - - -
7. Hydroclathus sp. - - - - - - - - -
8. Sargassum sp. - - - - - - - - -
9. Turbinaria sp. - - + - - - - - -
Rhodophyceae
10. Galidiella sp. - - - - - - - - -
11. Gracillaria sp. - - - - - - - - -
12. Porolithon sp. - - - - - - - - -
13. Lithothamnion sp. - - - - - - - - -
Spermatophyta
14. Phakellia sp. - - + - - - - - -
15. Euspongia sp. - - + - - - - - -
Porifera
16. Phakellia sp. - - - - - - - - -
17. Euspongia sp. - - - - - - + - -
18. Phyllospongia sp. + - - - - - - + -
19. Acarnus sp. - - - - - - - - -
20. Acathella sp. - - - - - - - - -
21. Clathria sp. - - - - - - - - -
22. Hiricinia sp. - - - - - - - + -
23. Spongilla sp. - - - - - - - - +
24. Raspailia sp. - - - - - - - - -
25. Petrosia sp. - - - - - - - - -

Table 3.19 (Contd…)
Sr.
Name 1 2 3 4 5 6 7 9 10
No.
Alcyonaria
26. Juncella sp. + - - - - - - - -
27. Alcyonium sp. - - - - - - - - -
28. Alcyonid sp. - - - - - - - - -
29. Antipathes sp. - - - - - - - - -
30. Sclcrophytum sp. - - - - - - - - -
31. Sarcophytum sp. - - - - - - - - -
32. Scirpearia sp. - - - - - - - - -
33. Verucella sp. + - - - - - - - -
34. Virgularia sp. - - - - - - - - -
35. Acanthogorgia sp. - - - - - - - - -
Scleractinia
36. Solitary coral + - - - - - - - -
37. Fungia sp. - + - - - - - - -
Hydroida
38. Halicornaria insignis - - - - - - - - -
Polychaeta
39. Eunice sp. - - - - - - - - -
40. Nereid - - - - - + - - -
Brachyura
41. Uca sp. - - - - + - - - -
Anomura
42. Hermitcrab - - - - - - - - -
Gastropoda
43. Xancus sp. - - + - - - - + -
44. Lambis lambis - - - - - - - + -
45. Oliva sp. - - + - - - - - -
46. Conus sp. - - + - - - - - -
Murex sp.
47. - - + - + - - - -
48. Terebra sp. - - - - - - - - -
49. Thais sp. - - + - - - - - -
50. Umbonium sp. - - + - - - - - -
51. Siliqua radiata - - - - - - - - -

Table 3.19 (Contd…)
Sr.
Name 1 2 3 4 5 6 7 9 10
No.
Bivalvia
52. Pecten sp. - - - - - - - - -
53. Pinna sp. - + - - - + - - -
54. Pteria sp. - - - - - - - - -
55. Arca sp. - - - - - - - - -
56. Cardium sp. - - + - + - - - -
57. Donax sp. - - - + + - - - -
58. Solen sp. - - + - - - - + -
59. Tellina sp. - - - - + - - + -
60. Pinctada sp. - - - - - - - - -
61. Sunnetta sp. - - - - - - - + -
Scaphopoda
62. Dentalium sp. - - - - - - - - -
Echinodermata
63. Clypeaster sp. - - - - - - - - -
64. Astropecten sp. - - - - - - - + -
65. Salmacis sp. - - - + - - - - -
66. Sticopus sp. - - + - - - - + -
67. Ophiuroid - - + - - - - - -
68. Hologhuria atra - - + - - - - - -
69. H. Scabra - - + + - - - + -
70. Protoreaster lincki - - - - - - - - -
71. Pentaceros lincki - - - - - - - - -
72. Luidia maculata - - - - - - - + -
73. Pentacta fucata - - - - - - - - +
Urochardata
74. Rhodocynthia sp. - - - - - - - - -
75. Solitary ascidian - - - - - - - - -
76. Colonial ascidian - - - - - - - - -
77. Polycarpa sp. - - - - - - - - -
Pisces
78. Remora sp. - - - - - - - + -

Table 3.20
Density and Biomass of Meiofauna in Sediment Samples
Station Number mg (wet weight)
1 32 4.70
2 44 6.47
3 111 16.32
4 110 16.17
5 98 14.40
6 120 17.64
7 93 13.66
8 28 4.12
9 118 17.34
10 115 16.90
Values are expressed per 100 cm2 area

Table 3.21
Distribution Pattern of Corals, Live Corals (Percentage) and Seagrases
Sr. Name of Island Area Corals Live Sea grass
No. (ha) distribution Corals distribution
(sq.km.) (%) (sq.km.)
Mandapam Group
1. Shingle 12.69 2.0 46 0.21
2. Krusadai 65.80 1.5 33 3.0
3. Pullivasal & 9.95 & 16.58 4.0 14 5.0
Poomarichan
4. Manoli & Manoliputti 25.90 & 2.34 15.0 35 5.0
5. Musal 129.04 18.0 522 9.5
Keezhakarai Group
6. Mulli 10.20 7.0 25 2.0
7. Valai & Talairi 10.15 & 75.15 14.0 16 8.0
8. Appa 28.63 5.0 2 8.0
9. Poovarasanpatti & 0.25 & 6.75 6.0 50 11.5
Valimunai
10. Anaipur 11.00 5.0 37 14.0
Vember Group
11. Nallathanni 110.00 2.0 38 5.0
12. Pulivinichalli 6.12 7.0 38 1.5
13. Upputhanni 29.94 3.0 26 2.5
Tuticorin Group
14. Kasuwar 19.50 6.0 5 3.0
15. Karaichalli 16.46 0.3 4 1.0
16. Vilanguchalli 0.95 1.0 8 1.5
17. Van 16.00 2.5 7 5.0
Source : Resources Information System for Gulf of Mannar (India), GOI, DOD and Integrated
Coastal and Marine Area Management Project Directorate, Chennai, April 2001

Table 3.22
Maximum diversity index values of Corals
in 21 islands of Gulf of Mannar
Sr. No Name of islands Maximum diversity index
1 Shingle 2.48
2 Krusadai 2.56
3 Pullivasal 2.39
4 Poomarichan 2.48
5 Manoliputti 2.48
6 Manoli 2.56
7 Musal 2.48
8 Mulli 2.3
9 Valai 1.79
10 Talairi 2.07
11 Appa 0.69
12 Valimunai 1.61
13 Anaipur 1.79
14 Nallathanni 1.79
15 Pulivinichalli 1.61
16 Upputhanni 1.94
17 Karaichalli 1.38
18 Vilanguchalli 0
19 Kasuwar 1.79
20 Van 1.79
Formula : Maximum Diversity Index (MD) = log2 (TT)
Where TT is total taxa
Source : Evaluation of Fourteen Trophic State Indices for Phytoplankton of Indian Lakes
and Reservoirs
Environmental Pollution (Series A) 27 : 143-153
Editor : Sullivan P.I and Carpenter S.R (1982)

Table 3.23
List of Fishlanding Centres within Sethusamudram Ship Canal Zone
Palk Bay 44. Pasipattinam
1. Point Calimere 45. Damodarapattinam
2. Muthupet 46. Naraneiyandal
3. Adiramapattinam 47. Valasapattinam
4. Karayur Street 48. Purakkudi
5. Sunnambukkarar Street 49. Purakkudi
6. Eripurakarai 50. Nambuthalai
7. Kollakadu 51. Soliyakudi
8. Pudupattinam 52. Pudupattinam
9. Mallipallinam 53. Mullimunai
10. Chinnamanai 54. Karankadu
11. Manova Colony 55. Morepannal
12. Pillaiyar Thidd 56. Thiruppalaikudi
13. Sethubavachatram 57. Devipattinam
14. Kalumankuda 58. Mudiveerampattinam
15. Othaiveedu 59. Pazhaneelavalasai
16. Karankuda 60. Puduvalasai
17. Sambaipattinam 61. Pannaikulam
18. Adamcathevan 62. Alagankulam
19. Senthalaipattinam 63. Athankarai
20. Mantadipattinam 64. Thoppuvalasai
21. Puthur 65. Dhangavalasai
22. Somanathanpattinam 66. Alagathanvalasai
23. Vallabanpattinam 67. Eiyerumeeli
24. Vadakur 68. Pirrappanvalasai
25. Kattumavadi 69. Pillaimadam
26. Pradabiramanpattinam 70. Munaikkadu
27. Krishnajiramanpattinam 71. Mandapam – Palk Bay
28. Thulasipattinam 72. Pamban light house
29. Thulasipattinam – South 73. Akkalmadam
30. Ammapattinam 74. Nallupanai
31. Pudukudi – North 75. Thangachimadam
32. Pudukudi – South 76. Villundy
33. Kottaipattinam 77. Pillaikulam
34. Jegathipattinam 78. Vadakadu
35. Embavayal 79. Narikkzhli
36. Palakudi 80. Oolaiyadipallam
37. Kumarappan Vayal 81. Oolaikuda
38. Gopalpattinam 82. Changumaal
39. Pudur 83. Kariyur
40. Arsantarai 84. Cherankottai
41. Pudukuda 85. Kothandaramarkovil
42. Sundarapandiyanpattinam 86. Moontayiruppuchatram
43. Theerthanthanam 87. Dhanushkodi

Table 3.23 (Contd…)
Gulf of Mannar
1. Oothaiputti 21. Keelakkarai
2. Paradi 22. Sennaevadi
3. Thavukadu 23. Vallinokkam
4. Otthathalai 24. Mundal
5. Rameswarampudu Road 25. Mariyur
6. Naduthurai 26. Oppillan
7. Kadarpachapadu 27. Mukaiyur
8. Punkammapadu 28. Narippaiyur
9. Kundukaal point 29. Rochemaanagar
10. Chinnappaliam 30. Vembar
11. Therkuvadi 31. Keelavaipar
12. Thonithurai 32. Sippikulam
13. Vedalai 33. Pattinamarudur
14. Seeniyappadharga 34. Taruvaikulam
15. Pudumadam 35. Vellapatti
16. Thalaithoppu 36. Alangarathattu
17. Muthupettai 37. Tuticorin-North
18. Periyapattinam 38. Tuticorin-Fishing Harbour
19. Kalimankundu 39. Titocorin- South
20. Sethukkarai 40. Tuticorin Harbour Point
Source : CMFRI, Kochi (1998)

Table 3.24
Shannon Weaver Diversity Index (H’ value) for the Ornamental Fishes
Recorded Around each Island in the Gulf of Mannar
Sr. Island Species H’ Families Species
No. Richness/ value Observed Observed
Density
1 Van 1.96/10 sq.m. 2.46 21 49
2 Kasuwar 1.76/10 sq.m 2.47 22 44
3 Vilanguchalli 0.92/10 sq.m 1.35 23 11
4 Karaichalli 2.80/10 sq.m 2.34 21 70
5 Upputhanni 2.00/10 sq.m 2.47 22 50
6 Pulivinichalli 2.52/10 sq.m. 2.78 22 63
7 Nallathanni 3.24/10 sq.m. 2.54 22 81
8 Anaipur 2.52/10 sq.m. 2.92 21 63
9 Valimunai 2.40/10 sq.m. 3.40 20 60
10 Poovarasanpatti 0.88/10 sq.m. 1.09 12 22
11 Appa 2.68/10 sq.m. 2.72 23 67
12 Talairi 2.36/10 sq.m. 2.27 20 5
13 Valai 2.36/10 sq.m. 2.39 18 5
14 Mulli 2.36/10 sq.m. 2.29 19 59
15 Musal 2.64/10 sq.m. 2.78 23 66
16 Manoli 2.64/10 sq.m. 2.56 23 66
17 Manoliputti 2.16/10 sq.m. 2.60 22 54
18 Poomarichan 1.52/10 sq.m. 1.46 19 38
19 Pullivasal 0.60/10 sq.m. 0.76 10 15
20 Krusadai 1.24/10 sq.m. 1.24 17 31
21 Shingle 2.00/10 sq.m. 2.81 20 50
Source : Resources Information System for Gulf of Mannar (India), GOI, DOD,
Integrated
Coastal and Marine Area Management Project Directorate, Chennai, April 2001

Table 3.25
Commercially Important Species Contributing to Fishery in
the Gulf of Mannar and the Palk Bay
Silver belles : Rays :
Leioganthus bindus Dasyatis bleekeri
Leioganthus dussumeiri Dasyatis uamak
Leioganthus jonesi Dasyatis sephen
Leioganthus brevirostris Rhinotera javanica
Leioganthus berbis Amphiotistius imbricatus
Leioganthus equulus Amphiotistius kuhni
Gazza minuta Aetobatus narinari
Gazza achlamya Aetobatus flagellum
Secutor insidiator Gymura poecilura
Secutor ruconius 7 Carangids :
Seleroides leptolepis
Sardines :
Sardinells fimbriata Caranx ignobilis
Sardinells gibbosa Atule mate
Sardinells albella Carangoides malabaricus
Sardinells sirm Carangoides sexfasciatus
Mackerel : Prawns :
Rastrelliger kanagurta Penulirus ornatus
Tunas : Lobsters :
Auxis thazard Panulirus ornatus
Euthynnus affinis Panulirus homarus
Sarda orientalis Panulirus versioclor
Thunnus tonggol Thenus orientalis
Seerfishes : Sharks
Scomberomorus commerson Carcharhinus sorrah
Scomberomorus guttatus Rhizoprionodon actus
Perches : Scoliodon laticaudus
Lenthrinus nebulosus Loxodon macrorhinus
Siganus canaliculatus Sclaenids :
Lutjanus spp. Otolithes rubber
Epinephelus spp. Johnius maculates
Plectorhynchus spp. Johnius dussumieri
Diagramma spp. Johnieops aneus
Upeneus spp. Protonibea diacanthus
Plotosus spp. Threadfin Breams :
Psammoperca waigiensis Nemipterus delagoae
Theropon spp. Nemipterus japonicus
Serraus spp. Goatfishes :
Chaetodon spp. Parupeneus indicus
Acanthurus spp. Parupeneus cinnabarius
Whitebaits : Upeneus sulphures
Stolephorus indicus Upeneus vittatus
Stolephorus batabiensis Upeneus sundaicus
Stolephorus devisi
Source : CMFRI, Kochi (1998)

Table 3.26
Major Fishing Gears used in the Gulf of Mannar and the Palk Bay
Types of Fishes
Gear
Shoreseines (Kara valai type) - Operated with the help of thony (palnkbuilt
Tuticorin type) fitted with outboard engine,
targeting the small pelagics
Shoreseines (Ola valai0 - Operated with the help of vaththai )plankbuilt
Tuticorin type) non-motorized boat, targeting
mainly the shrimps anf the pelagics
Boatseine - Operated with vallom (plank-built Tuticorin type
boat with inboard engine) and fiberglass boat
with outboard engine
Gillnets
Chalavalai or koolabalai - Mainly small pelagics
Vala valai or podivalai - Mainly small pelagics
Paravalai -
Thirukkaivalai - Raya
Namduvalai - Crabs, lobsters, Drepane spp. etc.
Chanku madi -
Paruvalai - Perches, oceanic tuna
Hooks & lines
Longlines - Perches, catfishes, sharks etc.
Trawl lines - Seerfishes, tunas, sharks, carangids etc.
Trawlers - Demersals
Kalamkatti valai - Operated utilizing the tides, smaller inshore
fishes prevented escaping with recording tide
Traps - Reef fishes, lobsters
Handpicking - Macro algae, holothurians
Source : CMFRI, Kochi (1998)

Table 3.27
Marine Fish landings in the Gulf of Mannar during 1992-96 (In Tonnes)
Year Average 5 of Total
Name of Group
(1992-96) (Average)
1992 1993 1994 1995 1996
PELAGIC 30826 30770 35872 57226 58759 42691 54.38
DEMERAL 17256 25756 30760 29107 33844 27364 34.85
CRUSTACEANS 2546 2887 7878 4777 4265 4471 5069
MOLLUSCS 4697 1627 3699 3871 6028 3985 5.08
TOTAL 55325 61141 78210 94981 102897 78511 100
Max. sustainable yield for Pelagic (A) - 44600 tonnes
Current production - 42700 tonnes
Max. sustainable yield for Demersal (B-D) - 35200 tonnes
Current production - 37900 tonnes
Exploitation in excess of sustainable yield - 800 tonnes
GOM production in Tamil Nadu - 20%
Production rate - per sq. km - 14 tonnes
Production rate - per fishermen/yr - 0.683 tonnes
Production rate - per sq. km - 14 tonnes
Production rate - per active fishermen/yr - 2.24 tonnes
Source : CMFRI, Kochi (1998)

Table 3.28
Composition of Different Groups in Marine Fish Landings in
the Gulf of Mannar (Catch in Tonnes)
Name of Fish 1992 1993 1994 1995 1996
ELASMOBRANCHS
Sharks 1855 1401 992 929 600
Skates 194 61 10 62 191
Rays 1960 3200 2399 2989 2509
EELS 0 1 1 5 43
CATFISHES 411 575 180 313 553
CLUPEIDS
Wolf herring 810 1245 771 590 1014
Oil Sardine 7 26 0 1288 1419
Other Saridnes 11680 14383 15124 29052 31059
Other Shads 109 97 383 641 487
Stolephorus 2464 1042 1699 1601 2225
Thryssa 1180 1495 2473 2337 1812
Other Clupeids 1724 1297 3615 2209 2941
BOMBAY DUCK 0 17 0 7 0
LIZARD FISHES 704 1461 1288 2100 1527
HALF BEAKS] & 366 342 343 452 824
FULL BEAKS]
FLYING FISHES 8 2 1 2 7
PERCHES
Rock code 656 1264 1108 779 659
Shappers 467 649 677 636 491
Pig-face breams 2291 4393 5184 4432 6266
Threadfin breams 1443 1540 1955 2571 2165
Other Perches 984 1641 1439 3204 2707
GOATFISHERS 1238 1085 1103 1097 732
THREADFINS 101 44 286 152 42
CROAKERS 1225 949 1736 1951 2133
RIBBON FISHES 1383 561 91 26 312
CARANGIDS
Horse Mackerel 0 0 25 16 91
Scads 2 4 1 39 74
Leather-jackets 115 61 141 443 552
Other Carangids 3178 2827 4098 4556 4131
SILVERVELLIES 3776 7228 11024 6548 42354
BIG-JAWED JUMPER 140 81 44 325 64

Table 3.28 (Contd…)
Name of Fish 1992 1993 1994 1995 1996
POMFRETS
Black pomfret 15 2 54 3 21
Silver pomfret 43 27 85 134 73
MACKERELS 0 3 0 0 0
India makerel 213 1145 556 4620 3711
Other mackerel 0 0 0 3 0
SEER FISHES
S. commersoni 774 1052 1209 2174 1797
S. guttatus 33 16 75 157 3
S. lineolatus 13 11 19 18 13
Acanthocybium spp. 2 0 0 0 0
TUNNIES
E. affinis 1376 482 511 285 582
Auxis spp. 279 11 62 52 27
K. pelamis 3 4 7 1 0
Other tunnies 16 6 15 20 19
BILL FSIHES 137 148 78 34 135
BARRACUDAS 1142 1666 1487 2467 2763
MULLETS 11 14 105 40 335
FLAT FISHES
Halibut 40 259 130 95 5
Flounders 0 0 17 0 0
Soles 49 23 27 46 112
CRUSTACEANS
Penaeid prawns 1562 1558 4278 3034 2529
Non-penaeid prawns 6 157 2347 643 108
Lobsters 252 257 309 191 132
Crabs 726 914 944 891 1017
Stomatopods 0 0 0 18 479
MOLLUSCS
Bivalves 10 1 2 28 0
Gastopods 13 18 137 109 261
Cephalopods 4674 1606 3560 3734 5766
MISCELLANEOUS 3151 2838 3959 4417 2812
TOTAL 55325 61141 78210 94981 102897
Source : CMFRI, Kochi (1998)

Table 3.29
Composition of Trawl Catches in the Gulf of Mannar
Percent
Types of Fishes
Elasmobranches
a. Sharks 0.002
b. Rays 7.717
Catfishes 0.959
Clupeids
a. Wolf herring 0.021
b. Oil sardine 0.059
c. Other sardines 1.321
d. Hilsa shad 0.375
e. Other shads 0.375
f. Anchovies
Colilia 0.004
Stolephorus 0.578
Thryssa 7.594
Other clupeids 0.463
Rock cods 0.031
Pig-face breams 0.036
Threadfin breams 0.033
Other perches 2.035
Snappers 0.002
Goatfishes 1.097
Threadfins 0.159
Croakers 5.630
Ribbon fishes 0.008
Caraginds 3.371
a. Leather jackets 0.004
b. Other carangids 0.496
Silver bellies 38.331
Big jawed jumper 0.010
Pomfrets
a. Black pomfret 0.010
b. Silver pomfret 0.073
c. Chinese pomfret 0.002
Indian mackerel 0.025
Seerfishes 0.396
Barracuda 0.241
Mullets 0.017
Flatfishes
a. Soles 0.438
Crustaceans
a. Penaeid prawns 11.913
b. Non-penaeid prawns 0.004
c. Crabs 3.373
d. Stomatopods 0.433
Cephalopoda 0.611
Miscellaneous 12.115
Total 100.00
Source : CMFRI, Kochi (1998)

Table 3.30
Composition of the Trawl Catches at
Pamban, Rameswaram and Tuticorin
Pamban and Rameswaram
Component Tuticorin
(%)
Silver bellies 44.0 28.0
Penaeid prawns 12.0 12.0
Thryssa 0.1 21.0
Rays 12.0 0.1
Carangids 1.0 10.0
Croaders 7.0 3.0
Crabs 5.0 0.01
Perches 2.0 2.0
Sardines 2.0 0.3
Goatfishes 2.0 0.0
Stolephorus 0.02 2.0
Catfishes 1.5 0.02
Seerfishes 0.0 1.0
Others 11.38 20.57
Source : CMFRI, Kochi (1998)

Table 3.31
Pearl Oyster Paars in the Gulf of Mannar and the Palk Bay
Group Paars
I Inner Pamban group 1. Pamban karai
2. Pamban velangu
II Pamban Periya paar group 3. Pamban periya paar
III Musal Tivu group 4. Musal tivu paar
5. Cholava karai paar
IV Keelakkarai group 6. Vallai malai karai paar
7. Vallai malai velagu paar
8. Anna paar
V Valinokkam group 9. Valinukam paar
10. Valinukam thundu paar
11. Nalla tanni tivu paar
VI Inner Vemba group 12. Uppu tanni tivu paar
13. Vemabar karai paar
14. Kumulam paar
VII Outer Vembar group 15. Vembar periya paar
VIII Outer Vaipar group 16. Vaipar periyar paar
IX Inner Vaipar group 17. Devi paar
18. Parnanthu paar
19. Paduthamarikan paar
20. Paduthanmarikan paar
X Cruxian group 21. Cruxian paar
22. Tuticorin kuda paar
23. Cruxian thundu paar
24. Vantivu arupagam paar
XI Utti paar group 25. Nagarai paar
26. Uttipaar
27. Petha paar
28. Uduruvi paar
29. Kilathi paar
30. Athuvai aurpagam paar
31. Patharai paar
XII Pasi paar group 32. Attonbotu paar
33. Pasi paar
XIII Tholayiram paar group 34. Tholayiram paar
35. Koothadiyar paar
XIV Kanna tivu group 36. Thundu paar
37. Kanna tivu arupagam paar
Source : CMFRI, Kochi (1998)

Table 3.32
Distribution of Seagrass in the Islands of Gulf of Mannar
Sr.
Poovarasanpatti
No.
Poomarichan
Vilanguchalli
Species
Pulivinichalli
Upputhanni
Nallathanni
Manoliputti
Karaichalli
Valimunai
Pullivasal
Krusadai
Kasuwar
Anaipar
Shingle
Manoli
Talairi
Musal
Appa
Valai
Mulli
Van
1 Cymodocea + + + + + + + + + + + + + + + + + + + +
serrulata
2 Cymodocea + + + + + + + + + + + + + + + +
rotundata
3 Syringodium ++ + + + + + + + + + + + + + + + + + + +
isoetifolium
4 Halodule + + + + + + + + + + + + + + + +
uninervis
5 Halodule ovalis + + + + + + + + + + + + + + + + + + + +
6 Halophila ++ + + + + + + + + + + + + + + + + + + +
ovata
7 Thalassia ++ + + + + + + + + + + + + + + + + + + +
hemprichii
8 Enhalus + + + + + +
acoroides
9 Halophila ++ + + + + + + + + + + + + + + + + + + +
stipulacea
10 Halophila ++ + + + + + + + + + + + + + + + + + + +
decipiens
11 Halophila ++ + + + + + + + + + + + + + + + + + + +
beccarii
12 Halodule ++ + + + + + + + + + + + + + + + + + + +
pinifolia
Source : Resources Information System for Gulf of Mannar (India), GOI,
DOD, Integrated
Coastal and Marine Area Management Project Directorate, Chennai, April 2001

Table 3.33
Maximum diversity index values of Seagrass
in 21 islands of Gulf of Mannar
Sr. No Name of island Maximum diversity index
1 Shingle 2.39
2 Krusadai 2.48
3 Pullivasal 2.48
4 Poomarichan 2.48
5 Manoliputti 2.48
6 Manoli 2.48
7 Musal 2.48
8 Mulli 2.39
9 Valai 2.39
10 Talairi 2.39
11 Appa 2.19
12 Poovarasanpatti 2.19
13 Valimunai 2.19
14 Anaipur 2.39
15 Nallathanni 2.39
16 Pulivinichalli 2.39
17 Upputhanni 2.3
18 Karaichalli 2.39
19 Vilanguchalli 2.39
20 Kasuwar 2.07
21 Van 2.19
Maximum Diversity Index (MD) = log2 (TT)
Formula :
Where TT is total taxa
Source: Evaluation of Fourteen Trophic State Indices for Phytoplankton
of Indian Lakes and Reservoirs
Environmental Pollution (Series A) 27 : 143-153
Editor : Sullivan P.I and Carpenter S.R (1982)

Table 3.34
Maximum diversity index values of Mangroves
in 21 islands of Gulf of Mannar
Sr. No Name of island Maximum diversity index
1 Shingle 2.48
2 Krusadai 2.56
3 Pullivasal 2.39
4 Poomarichan 2.48
5 Manoliputti 2.48
6 Manoli 2.56
7 Musal 2.48
8 Mulli 2.3
9 Valai 1.79
10 Talairi 2.07
11 Appa 0.69
12 Poovarasanpatti 0
13 Valimunai 1.61
14 Anaipur 1.79
15 Nallathanni 1.79
16 Pulivinichalli 1.69
17 Upputhanni 1.94
18 Karaichalli 1.38
19 Vilanguchalli 0
20 Kasuwar 1.79
21 Van 1.79
Maximum Diversity Index (MD) = log2 (TT)
Formula :
Where TT is total taxa
Source: Evaluation of Fourteen Trophic State Indices for Phytoplankton
of Indian Lakes and Reservoirs
Environmental Pollution (Series A) 27 : 143-153
Editor : Sullivan P.I and Carpenter S.R (1982)

Table 3.35
Mangrove Species in Coasts of Palk Bay and Gulf of Mannar
Type
Name
Rhizophora apiculata
True mangrove (Tree)
Ceriops tagal True mangrove (Shrub)
Avicennia marina True mangrove (Tree)
Derris trifoliate Mangrove associate (Tree)
Cyanometra ramiflora Mangrove associate (Shrub)
Acanthus iliciformis Mangrove associate (Shrub)
Myriostachya wightiana Mangrove associate (Grass)
Phoenix paludosa Minor Mangrove (Plam)

Table 3.36
Distribution of Mangrove Vegetation in the Islands of Gulf of Mannar
Sr.
No.
Poovarasanpatti
Poomarichan
Vilanguchalli
Pulivinichalli
Species
Upputhanni
Nallathanni
Manoliputti
Karaichalli
Valimunai
Pullivasal
Krusadai
Kasuwar
Anaipar
Shingle
Manoli
Talairi
Musal
Appa
Valai
Mulli
Van
1 + + + + + + + + + + ++ + + +
Avicennia
marina
2 + + + + ++ + + +
Rhizophora
mucronata
3 + + + ++ + + +
Ceriops tagal
4 + + + ++ + + +
Bruguiera
cylindrica
5 + + + +
Lunmitzera
racemosa
6 + + + + + + + + ++ + + + + ++ + + +
Pemphis
acidula
7 ++ +
Excoecaria
agaloocha
8 +
Aegiceras
corniculatum
9 + + +
Rhizophora
apiculata
ASSOCIATED SPECIES
10 + + + + + + + + ++ + + + + ++ + + +
Salvadora
persiea
11 + + + + +
Pandanus sp.
12 + + + + + + + + + + + + ++ + + +
Sesuvitun sp
13 + + + + + + + + + + + + ++ + + +
Scaevola
plumieri
14 + + + +
Suaeda sp.
15 + + + +
Salicornia
brachiata
16 + + + + + + + + + + + + + ++ + + +
Thespesia
populnea

Table 3.37
Annual Primary Productivity (Gross) in Certain Marine Environments
as Grams Carbon per square meter Sea Surface
Production gC/m2/year
Locality
Barents Sea 170-330
English Channel 60-98
Georges Bank 309
North Sea 57-82
Long Island Sound 470
Off Hawaii (open ocean) 21
Off Hawaii (inshore) 123
Turtle grass bed (Florida) 4650
Hawaiian coral reef 2900
Shelf waters off New York (shallow coastal region) 160
(Continental slope) 100
North Central Sargasso Sea 78
Temperature oceans 100-150
Equator 110-146
Barren tropical oceans 50
Cochin back water 281
West coast of India (within 50 m depth) 434
East coast (continental shelf) 230
Kavaratti lagoon (Laccadives) 2250
Minicoy reef 3000
Mandapam reef 2500
Andaman reef (Port Blair) 1200
Gulf of Mannar (inshore within 10 m depth) 745
Source : Bull. CMFRI, No. 22 (1970)

Table 3.38
Coral fauna around the Mandapam Group of Islands
Species of Coral Fauna Observed around Mandapam Group of Islands
Genus : Pocillopora :
P. damicornis p. danae
Genus : I. Acropora
A. formosa A. nobilis
A. corymbosa (Lamarck)
A. erythraea
. surculosa (Dana) A. hyacinthus (Dana)
Genus : III. Montipora
M. divaricata (Briiggemann)
M. foliosa
M. digitata (Dana)
Genus : IV. Porites :
P. fragosa (Dana)
P. solida (Forskal)
p. alveolata (Milne Edwards and Haime)
P. thurstoni (Pillai)
P. compressa (Dana)
P. exserta (Pillai)
P. nodifera (Klunzinger)
P. (svnaraea) convexa
P. lutea P. mannarensis
Genus : V Favia
F. pallida
Genus : VI Favites
F. abdita (Ellis and Sollander)
Genus : VII Goniostrea. Spp.
Other coral species observed :
Platygyra lamellina (Ehrenberg) Leptoria phrygia (Ellis and Sollander)
Hydrophora spp. Leptastrea transversa (Klunzinger)
Leptastrea purpurea (Dana) Cyphastrea spp.
Symphyllia spp. Echinopora lamellosa
Source : Resources Information System for Gulf of Mannar
(India), GOI, DOD,

Integrated Coastal and Marine Area Management Project Directorate,
Chennai, April 2001

Table 3.39
Summary of Underwater Observations on Shelter and Food of Various Coral
Reef Associated Fauna in the Mandapam Group of Islands
Family Name Species Shelter Food items
Holocentridae Sargocentron spp. (silver RE & RF Benthic
spot squirrel fish) crustanceans
Myripristis spp. URS Plankton
Violet soldier fish
Pomacanthidae Pomacanthus RE & URS Sponges and
imperator encrusting
Abudefduf URS Organisms
saxatilis Zooplankton
(Sergeant major)
Pomacentridae Amphiprion clarkii RE & Omnivorous
associated with sea
anemone
Chaetodontidae Chaetodon collaris RE & URS Coral polyp
C. melanotus RE & URS soft corals
C. meyeri E & URS coral polyp
C. auriga RF & URS small Invertebrates
Serranidae RE & URS
Anyperodon Fish and
leucogrammicus crustacean
Scaridae Scarus sordidus RF & RE Algae
S. gibbus RE Algae
scarus ghbus RE Algae
Lutjanidae Lutjanus bohar URS Fish and
L.Monostigma URS crustacean
Fish and
crustacean
Lethrinidae Lethrinus spp. RF & URS Benthic
Invertebrates
Note: RF-Reef flat, RE-Reef edge, URS-Upper reef slope
Source : Resources Information System for Gulf of Mannar
(India), GOI, DOD,
Integrated Coastal and Marine Area Management Project Directorate,
Chennai, April 2001

Table 3.40
Marine Water Quality in Palk Bay (Latitude 9O44′)
Parameters Sample Location & Distance from shore
1 2 3 4
0.5 km 5.0 km 10.0 km 15 km
(depth 2 m) (depth 4 m) (depth 6 m) (depth 7 m)
Temperature, OC Surface 29.00 29.00 29.00 29.50
Bottom 28.50 28.00 28.00 28.80
Suspended Solids, Surface 28.50 30.00 28.00 30.40
mg/l Bottom 34.00 26.00 34.00 23.00
pH Surface 8.20 8.20 8.10 8.20
Bottom 8.20 8.20 8.10 8.10
Salinity, ‰ Surface 30.68 31.15 31.60 31.50
Bottom 32.10 30.60 32.50 30.50
Dissolved oxygen, Surface 4.60 4.27 4.48 50.00
ml/l Bottom 4.10 4.18 4.08 4.18
Total phosphorus, Surface 2.20 1.10 1.60 0.80
µmol/l Bottom 1.19 1.00 2.40 -
Total nitrogen, Surface 28.80 30.30 32.10 30.8
µmol/l Bottom 23.10 35.30 34.00 29.70
BOD, mg/l Surface 2.88 3.10 2.43 1.37
Bottom 2.55 1.35 0.08 0.31
PHC, µg/l Surface 9.10 9.80 13.30 8.20
Bottom - 1.50 - -
Cadmium, µg/l Surface 0.70 0.10 0.68 0.22
Bottom 0.14 0.24 0.68 0.62
Lead, µg/l Surface 1.28 ND 2.64 2.02
Bottom 3.00 2.40 3.94 2.18
Mercury, µg/l Surface 0.48 0.10 0.21 0.46
Bottom 0.70 0.27 0.19 0.63
Source : COMPAS report prepared by CECRI

Table 3.41
Distribution of Zooplankton in Palk Bay near the Proposed Channel
Parameters Levels Observed
Biomass, ml/100m3 0.48-1.92
Population no/100m3 6065-36837
Total groups no. 8-12
Major groups, %
Copepoda 47-70
Foraminifera 5.66-17.79
Ostracoda 1.4-3.8
Polychaeta 1.6-1.89
Cumacea 0.6-1.89
Amphipoda 1.09-3.77
Mysids 1.14-1.89
Decapod larvae 2.27-5.43
Stomatopod Larvae 0.61-5.43
Fish Eggs 3.68-7.95
Fish Larvae 0.61-2.27
Euphasids 1.14-1.60
Source : COMPAS report prepared by CECRI

Table 2.42
Distribution of Decapods in Palk Bay
+++
Penaeus indicus
+
P. latiulcatus
++
Metapenaeus affinis
+
Parapenaeopsis maxillipedo
++
P. cornuta
+
P. tenella
++
Macrobrachium rosenbergii
++
M. aemulium
+
Hippolyty ventricosa

Table 2.43
Distribution of Desmospongiae and Corals in Palk Bay
Distribution
Species
Demospongiae
++
Spongia officinalis
+
Heteronema erecta
+
Hyattella cribriformis
+
Ircinia fusca
++
Fasciospongia cavemosa
+
Dysidea herbacea
++
Dendrilla nigra
+
Psammaplysilla purpurea
+
Haliclonia exigua
++
Iotrochota baculifera
+
Sigmadocia fibulata
+
Taxadocia fibulata
+
Orina sagittaria
+
Damiria simplex
Callyspongia diffusa ++
++
Echinodictyum gorgonoides
++
Damiriana schmidti
+
Rhabderemia indica
+
Endectyon thurstoni
+
Tedania anhelans
+
Acarnus thielei
++
Aulospongus tubulatus
++
Clathria, frondifera
+
C. indica
++
Mycale grandis
+
Mycalecarmia monanchorata
+
Zygomycale parishii
+
Toxemna tubulata
+
Biemna fortiis
+
Axinella tenuidigitata
+
Higginsia mixta
++
Myrmekioderma granulata
++
Trachyopsis halichondroides

Table 2.43 Contd…
Distribution
Species
+
Spirastrella coccinea
++
Timea stellata
T. stelligera +

+
Suberites carnosus
++
Laxosuberites cruciatus
++
Aaptos aaptos
++
Placospongia carinata
++
Cliona celata
+
C. vastifica
+
Prostylyssa foetida
+
Stellettinopsis simplex
+
Epipolasis topsenti
+
Tethya robusta
+
T. diploderma
+
Echionemia acervus
+
Myriastra purpurea
+
Aurora globostellate
++
Geodia perarmata
+
Geodia lindgreni
+
Cinachyra cavemosa
+
Paratetilla bacca
+
Lophacanthus rhabdophorus
+
Dercitopsis minor
+
Pachamphilla dendyi
+
Corticium candelabrum
+
Corticium acanthastrum

+
Plakina monolopha
+
Plakina acantholopha
+
Chondrilla sacciformis

Table 3.44
Distribution (kg/hr) of Various Fishery Resources along
Palk Bay SE Coast of India during 1985-90
10O/80O
Groups
Elasmobranchs 0
Carrangids 6.62
Nemipterids 0
Epinephelus sp. 7.43
Lethrinus sp. 10.05
Lutjanus sp. 5.48
Lutianus sp. 0
Pomadasys sp. 17.14
Diagramma sp. 2.74
Pentaprion sp. 1.37
Other perches 2.05
Cat fishes 0
Sciaenids 0
Lizard fishes 0
Goat fishes 2.45
Leiognathus sp. 11.22
Sphryaena sp. 0
Seer Fish 0
Mackeral 0
Dussumieria sp. 0
Psenes indicus 0
Psenopsis cyaena 0
Priacanthus sp. 0
Balistids 0.59
Miscell. Fish 15.7
Jelly fish 0
Crustaceans and Cephalopods 6.97
Total catch 89.71

Table 3.45
Abundance of Demersal Finfish Resources (kg/hr) in
SE Coast of India EEZ
Area 10O/80O
Major groups/Species
51-100 m depth
Sharks -
Skates -
Rays -
Carangids 451
Rastrelliger Kanagurta 227
Silver bellies -
Threadfin breams 1
Lizard fish 1
Upeneus sp. -
Sphyraena sp. -
Priacanthus sp. -
Perches 303
Platycephalus sp. -
Flat fish -
Trichiurus sp. -
Cat fish -
Other finfish 5
Miscell. Fish 41
Total 1035

Table 3.46
Perches Abundance in kg along S.E. Coast (Palk Bay)
Depth Latitude Lutjanus Lethrinus Serranids Plectorhynchus Other Total
(m) Perches
10O
0-50 3 - 29 - 18 50
10O
51-100 93 193 17 264 270 837
10O
101-150 14 - - - - 14
4. Land Environment
The objective of the present study is to evaluate the environmental impacts
on various land and ocean features in the project area as a result of dredging
operations to be carried out in Adam Bridge area, parts of Gulf of Mannar and Palk
Bay to create the navigational channel. The dredged material is required to be
assessed both qualitatively and quantitatively to arrive at option for its disposal either
on land or in sea. It is therefore imperative to accurately define the baseline status of
various environmental parameters pertaining to both land and the sea and to carefully
examine the environmental impacts on them. The option of disposal of dredged

material has to be selected in such a manner so that impacts on Biosphere Reserves
can be prevented/minimized.
Satellite remote sensing data has proved to be highly reliable in delineating
the landuse and land cover of any region in a very limited time and in a cost-effective
manner due to its capability of providing very high spectral and radiometric integrity
and consistency. Satellite remote sensing data also facilitates accurate detection of
any change in the landuse pattern. The delineation of correct landuse pattern forms an
integral component of environmental impact assessment.
4.1 Objectives
The objectives of the present study are as follows :
• Delineation of various landuse and land cover classes in the study region
and estimation of their areal coverage through the analysis and digital
classification of satellite data
• Identification of potential dumping sites for dredged materials disposal
4.2 Data Used
Satellite data obtained in 1998 and 2002 has been used for delineation of
landuse pattern and identification of dumping sites. The data obtained in 2002 was
mostly used to study change in landuse pattern and to select suitable dumping site
close to Adams Bridge provided the quality of dredged materials is suitable for
nourishment of soil.
1. Remote Sensing Data : In keeping with the climate of the area the following
cloud free satellite data were chosen and the quality was checked for cloud
and haze cover, striping, line drop out etc. The following data at the latitude
(09°05’00\"-09°25'00\") N longitude (79005'00\"-79035'00\") E were used:
A. Satellite data
Merged data PAN sharpened LISS III
IRS 1D LISS III scene
Path: 102 Row: 67 dated 02 Jun 2002
IRS 1D PAN
Path: 102 Row: 67 dated 08 May 2002

B. Collateral Data
Detailed location map
IRS 1D LISS-III multispectral data and PAN offer very high spatial resolution
of 23.5 m x 23.5 m and 5.8 m x 5.8 m with a swath width of 127 x 141 kms
and orbital cycle period of 24 days. The data is sensed in four spectral bands
viz., band 2 (0.52-0.59 µ), band 3 (0.62-0.69 µ), band 4 (0.77-0.86 µ) and
band 5 (1.55-1.76 µ) with 8-bit radiometric resolution providing a dynamic
display range of 0 to 255 which facilitates distinct representation of the
various classes and also enables subtle tonal and textural discrimination
among them. The spatial, spectral and radiometric resolutions of the remotely
sensed data are the three primary governing factors in the correct estimation of
various landuse and land cover classes through digital analysis and
classification of the data. The discriminability among the various classes can
be further increased using the different image interpretation keys of the
existing geomorphic and cultural features in the scene such as size, shape,
tone, colour, texure, pattern, association etc.
2. Toposheets and Thematic Maps : Relevant toposheets in 1:50,000 scale of
the Survey of India and landuse map in 1:1,000,000 scale published by the
National Atlas and Thematic Mapping Organization (NATMO) were used for
registration of the satellite data. These were also used as collateral data in the
digital analysis and classification of the satellite data.
3. Field Visit : In order to strengthen the classification scheme, field information
plays major role in clarification of IRS LISS III imagery. This filed visit
mainly includes collection of ground truth sample to establish ground control
points which are required to reference the satellite imageries to a known map
projection.
4.3 Hardware and Software Used
1. A highly configured computer was used for the digital image processing. The
system offers an integrated platform to carry out complex tasks necessary for
digital image processing.
2. Remote Sensing data was analyzed using EASI/PACE V 7.0 and Geomatica V
8.2 software loaded in a highly configured computer. The software package is

a collection of image processing functions necessary for pre-processing,
rectification, band combination, filtering, statistics, classification etc. Apart
from contrast stretching, there are large number of image processing
functions, that can be performed on this station. Further analysis was
performed in GIS (MAP INFO Professional 6.2 and ARC/INFO software)
environs.
4.4 Selection of Study Sites
Keeping in view the objectives of the study pertaining to land environment,
three different subscenes were extracted from the satellite data in order to map the
various landuse and land cover classes with finer detail. The study sites are as
follows:
1. Pamban island alone
2. Pamban island and the coastal wedge of Mandapam
3. Pamban island and an approximately 25 km. coastal buffer land stretching
along the Palk Bay and the Gulf of Mannar (1998 imagery)
4.5 Methodology
Landuse refers to man’s activities on land, which are utilitarian in nature,
whereas land cover represents the vegetation and other natural features such as
barren land, stony land, water bodies, marshy areas etc. The remote sensing data
records information essentially on land cover from which information on landuse has to
be inferred. The landuse/land cover classification system standardised for mapping
different agro-climatic zones by the Department of Space has been adopted. The
classification system has six major landuse classes at level I and 28 at level II (Table
4.1). These are listed below:
1. Urban or built-up land : This comprises mostly cultural
features including commercial and industrial areas
2. Agricultural land : This includes cropped areas, fallow lands
and plantation

3. Forest: This includes all lands administered as forests such as
dense, sparse, and degraded forests, mixed forest, scrub, forest
plantations, agriculture in forests etc.
4. Wastelands: Lands which have potential for the development
of vegetative cover but not being used due to different constraints are
classified under this category. This includes salt affected land,
gullied/eroded land, waterlogged area, marshy and swampy area, sandy
area and rocky outcrops etc.
5. Water bodies : Areas persistently covered by water such as
rivers/ streams, reservoirs/ tans, lakes/ponds, canals etc. are included
under this category
6. Others: Shifting cultivation, grassland, snow cover etc. are
included in this class.
The task of delineation of various landuse and land cover classes and site
selection for dumping of dredged materials was accomplished with recourse to the
step-wise methodology described as under.
Landuse and Land Cover Mapping
i. Preliminary analysis and reconnaissance study of the raw band data and false colour
composites (FCCs) generated in different band combinations with a view to
understanding the spectral signatures of the various spectral classes occurring on the
scene. This task was also supplemented through use of available toposheets and
other thematic maps such as landuse map published by NATMO. The FCCs were
stretched between 0 to 255 to utilise the full dynamic range of the display unit in
order to use the complete gray level range and optimise the contrast between various
features. It was felt that interpretation up to level II of the Department of Space is
not possible with consistent accuracy using FCC alone.
ii. Acquisition of representative ground truth samples from the field by means of a
Global Positioning System (GPS), providing a geometric accuracy which is
sufficient for accomplishing the task of digital image analysis successfully. The
ground truths were used for selecting the training pixels of different classes on the
FCCs with high geometric accuracy.

iii. Selection of representative training signatures for various landuse/land cover classes
on the basis of their spectral discriminability and ground truths.
iv. Digital classification of the multispectral satellite data using maximum likelihood
classifier using the training signatures extracted for the respective classes. All the
four spectral band data have been used in the classification. Reject classes, and
underrepresented and overrepresented classes have been minimised by interactive
iteration through careful selection of the training area based on the a-priori
probabilities of different classes.
Identification of Dumping Sites for Dredged Materials
Subsequent to the generation of classified images of the study sites, dumping
sites for the dredged materials were identified on the images by resorting to various
criteria discussed in detail later.
4.6 Data Interpretation
Analysis of False Colour Composites (Merged FCCs)
Using the imagery analysis program, merged false colour composites were
generated using IRS 1D LISS III and PAN, for the different study regions viz., Pamban
island and the coastal wedge of Mandapam, Pamban island alone in Red (band 3),
Green (band 2) and Blue (band 1) combination as shown in Plate I and Plate II
respectively. The interpretation of the FCCs was carried out using various image
interpretation keys such as tone, colour, size, shape, texture, pattern, and association
of the various landuse and land cover classes present in the study regions. In each
composite, the dark red colour represents dense vegetation, moderately red colour
represents moderately dense vegetation, and light reddish white colour represents
sparse vegetation. The plantations mainly comprise coconut and palm, which are
identified on the basis of both their reddish signature and characteristics pattern, and
the sparse plantations are displayed in reddish yellow colour. The dense scrub mostly
comprising Prosopis juliflora, a very common vegetation species occupying vast
stretches of land in the study areas in dark blue colour. Marshy land, backwater and
waterlogged areas appear in different shades of black. Water bodies appear in cyan
wherever they contain water, otherwise they are whitish in appearance. The barren
sandy areas are distinct by their characteristic white colour throughout the FCCs. The

interpretation of the FCCs was made easier using the ground truths and also, the
collateral data such as toposheets and landuse maps.
Morphologically the area is a coastal plain. The area is characterized by the
formation of coastal alluvium, sand and clay. There are patches of shrub forest in the
close vicinity of the project site and mostly towards the southern part of the Pamban
Island, seen brownish red in the FCC. Also, general vegetation area mainly includes
cropland or shrub forest. The shrubs are random and appears in different shades of
brown tone. Fringe vegetation and sand bar is prominently seen along the coastline in
the island. The central portion of the imagery is indicating the presence of barren
sandy area as interpreted from characteristic whitish tone of the sand. The imagery
also indicates the presence of turbid water towards northern part of the island and
appears in cyan or dull green colour. The degraded barren land is also present
towards the south-eastern part of the island as prominently seen in the FCC. Road
network was visible in the monitor while performing image-processing though not
visible in the FCC paper print, however the road network is colour coded in the
classified image (Plate III).
Analysis of Classified Images
The colour coded output of supervised classification and maximum likelihood
algorithm for Pamban Island and its surroundings is depicted in Plate III. In this
image, different colours are assigned to various classes as given in the legend. The
fringe areas of the inland shallow and deep sandy areas i.e. areas located close to the
sea are prone to flooding due to backwater intrusion in most part of the year.
The area statistics of the different feature classes present on the classified
image is given in Table 4.2 for the study region. The landuse/ landcover classification
indicates 4.772 % area covered by turbid water, 53.328 % vegetation cover (crop land,
shrubs, forests), 8.084 % fallow land etc.
Different classes are identified, alongwith the corresponding area. Most of the
water bodies are shallow containing turbid water. Few agricultural activities occur in
the area. The yellow colour in the landuse map indicates the cropland. The fallow is
found to be associated with agricultural lands. The shrub land is found to be present
inside the forest as well as outside and is reported an area of 8.331 %. and is
assigned by reddish colour. Small patches of water bodies are mainly concentrated

towards north-eastern part of the area and are assigned by the cyan colour in the land
use map. The degraded land is present towards the south-eastern part of the Island
and is assigned as deep brown colour. Road network as visible in full resolution is
represented as red lines in the colour coded output.
4.7 Identification of Dumping Sites for
Dredged Materials
The following criteria were used to identify potential sites for dumping of the
dredged materials:
i. Areas which are close to the proposed ship navigational route
ii. Areas which presently are not in use for any significant activity (commercial
or other)
iii. Shallow and deep areas which otherwise can be reclaimed for productive
utility
iv. Barren sandy areas which do not contain any vegetation cover and are also
classified as unproductive
v. Areas which are devoid of vegetation and areas which are not in close
proximity to the dense vegetation
vi. Areas which are not in proximity to the water bodies such as river, pond, back
water etc. to ensure prevention of erosion and siltation of dumped materials
into them so that their natural pristine status is conserved
vii. Areas which are easily accessible and trafficable
A detailed and thorough examination of the classified images of the satellite
data was carried out using the above mentioned criteria and the following sites were
proposed for dumping of dredged materials based on 1998 imageries.
i. The shallow and deep sandy areas lying in the Pamban island since most of these
areas are located in the narrow strip of the island through which the navigational
channel is proposed to be constructed. Likewise, the barren sandy areas occurring
in the island can also be used as dumping sites. The shallow and deep areas cover
20.32 sq.km. i.e. 2032 hectares which comprises 20.67% of the island whereas the
barren sandy areas alone stretch over 21.76 sq.km. i.e. 21.76 hectares which covers

22.13% of the island. In other words, nearly 42.8% of the island alone which covers
an area of 42.08 sq.km. i.e 4208 hectares can be selected for dumping sites. Even
effective utilization of 50% of the available area would serve as major dumping
sites within the island alone (i.e. nearly 20 sq.km. or 2000 hectares).
ii. Barren sandy areas occurr in the Pamban island and in the coastal wedge of
Mandapam area. The shallow and deep areas in this region are nearly same as that
of the Pamban island alone because these areas are dominantly confined to the
island only. However, an extensive barren sandy area is available in the coastal
wedge of the Mandapam region (over 140 sq.km. or 14000 hectares). Effective
utilization of a nominal 25% of the available area means that 35 sq.km. area is
available for dumping of the dredged materials.
Keeping in view the reduction in quantity of dredged material due to
realignment of route using navigational depths available in Gulf of Mannar, the
dredging activity will be restricted to an area in the vicinity of Adams Bridge over a
length of about 5 km and a width of about 500m. The quantity could depend on
bathymetry charts and the depth of dredging. It is proposed to dispose sand portion
into sea at a suitably identified location and the silt and clay can be disposed on
degraded land in Pamban island. The Plate IV shows proposed location for disposal of
dredged material as indicated in the marked area spreading over 753 hectares. The
area is degraded land and can be converted into cultivable land through nourishment
by dumping silt and clay with some portion of sand from dredged material.

Table 4.1
Land use/ land Cover Status in Pamban Island,
Based on the Satellite data of May, 2002
Category Inventory by IRS 1D LISS III + PAN May, 2002
Area, (ha) % to Total
Vegetation Cover 1 717.835 7.438
Vegetation Cover 2 2758.664 28.585
Fringe Vegetation 866.136 8.974
Turbid Water 460.603 4.772
Mud Flats 97.185 1.012
Sand bar 1261.951 13.076
Fallow land 776.699 8.048
Shrub 804.056 8.331
Barren sandy 427.754 4.432
Degraded land 1479.719 15.332
Total 9650.602 100

Table 4.2
Landuse/Land Cover Classification System
Level - I
Sr. No. Level - II
1. Built-up Land 1.1 Built-up land
1.2 Road
1.3 Railway
2. Agricultural Land 2.1 Crop land
2.2 Fallow (Residual)
3. Forest 3.1 Evergreen/Semi-evergreen forest
3.2 Deciduous forest
3.3 Degraded/Scrub land
3.4 Forest blank
3.5 Forest plantation
3.6 Mangrove
3.7 Cropland in forest
4. Wasteland 4.1 Salt affected land
4.2 Waterlogged land
Marshy/Swampy land
4.3
4.4 Gullied/Ravinous land
4.5 Land with or without scrub
4.6 Sandy area (coastal and dessertic)
4.6 Barren rocky/Stonywaste/sheetrock area
5. Water bodies 5.1 River/Stream
5.2 Lake/Reservoir
Tank/Canal
5.3
Grassland/Grazing land
6. Others 6.1
6.2 Shifting cultivation
6.3 Snow cover/Glacial area

5. Socio-economic
Environment
Along the coast in the Gulf of Mannar and the Palk Bay, there are 127 villages
and towns spread over 5 districts. Summary data on population area number of households
etc. is presented in Table 5.1. Detailed information for each one of these villages/ towns is
presented in Table 5.2 and 5.3.
5.1 Socio-economics of the Fishing Community
The project area contains a rich mix of people of different religions and castes.
There are 23,000 fisher-folk households with a population of 115,000 in about 70 fishing
villages/ hamlets. There are about 35,000 active fisher-folk and about 70% of them are
involved in direct fishing, 21% in fishing related activities and 9% in other activities.
The literacy rate among the communities living along the coast of Gulf of Mannar is
only 31%, far less than the state average (64%). While most of them (54%) do not have a
dwelling of their own and live in huts along the sandy beaches, 25% have semi permanent
and only 21% have concrete or tiled roof houses. Though majority (56%) of the fishermen
still depend on traditional catamaran for their fishing activities, 95% of them could not
operate continuously due to non-availability of net and other equipment. Only 10 percent of
the fisherfolk have ownership of means of production above Rs. 1,00,000 indicating the most
of the commercial trawlers are from outside the area. Hardly, 37% of the fisherfolk
households in the region have ownership on some sort of means of production. Per capita
income of a fishermen is just Rs. 3,943/- (1990-91), far less than the state average.
During this study a review of fishing activities in Ramnathpuram Dist. was taken up
based on 2000 census data. The number of male population involved in fishing is 29570

whereas who are involved in trade, marketing, net making and other allied activities those
are around 2200. The population of fisherwomen involved in fishing is about 1657 and
women involved in allied activities including trade are about 5500. Income status of
fisherfolk in 2000 census has shown a positive trend as compared to 1991 census where per
capita income was Rs. 3943/-. The per capita income according to 2000 census varies from
Rs. 3000 to Rs. 15000/- as per 2000 census data. Income status of fisherfolk in Dist.
Ramnathpuram shows 7849 people in less than Rs. 3000/- range, 13083 people in Rs. 3001-
6000 range, 19425 people in Rs. 6001-12000 category and about 2000 people in Rs. 12001-
15000 range. As per 2000 census data the fishing crafts comprise mechanised boats (1804
no.) and non-mechanised boats (5078 no.).
Currently the Gulf’s fishery is truly an open access resource. No property regime is
in place to manage or control access to this resource and as a result it is under heavy,
unsustainable pressure. Approximately 45,000 fisherfolk are currently fishing along the
Gulf’s waters. Ninety percent of them are artisanal fisherfolk (using small wind or small
engine powered craft) and 10% of them are mechanised trawler fishermen. Any person who
desires to take-up commercial fishing need only register with the Fisheries Department.
There is no limit on the number of fishing society in their local village or town. These
societies serve primarily as a savings-type of institution, and do not provide the fisherfolk
with the benefits of cooperative marketing, processing and management of the local fishing
areas for the common good.
The introduction of mechanised fishing to the region in the last 40 years has
gradually led to the breakdown of the specialised artisanal fishing community (some fishing
exclusively for prawn, others for sea cucumber, etc.) and has resulted in most fisherfolk
fishing for whatever they can find.
One of the serious problems in the area is the increasing human population at rates
considerably faster than that occurring in metropolitan areas of India. The rate of increase in
some villages could exceed 4% per annum, which is equivalent to a doubling of the
population within about 30 years. Unless the population is stabilized it is unlikely that the
ecosystems in the proposed reserve and surrounding areas will be sustainable. This problem
will be aggravated by the inevitably greater demands on resources from individuals as
economic development proceeds.

Currently there are very few, if any, income generating options for local fisherfolk.
There are no organised programs to provide local fisherfolk with technical and business
expertise in order to develop alternative livelihoods and income generating activities.
Existing research programs in the area are developing appropriate technologies for seaweed
farming, and pearl oyster farming, but they lack the mandate and expertise to transfer this
technology to local people.
5.2 Sample Survey
As part of the present study, a rapid survey was conducted on the socio-economic
aspects of the population in the project area, and to assess the public opinion on the proposed
canal project. The details of this survey alongwith the views expressed by the fishermen, the
officials of the Fisheries Department, Rameswaram, Naval Staff of Coast Guard Station,
Mandapam, and officials engaged in R&D work in the Gulf of Mannar and the Palk Bay on
the project are presented hereunder.
The Assistant Director of Fisheries, Govt. of Tamilnadu at Rameswaram was
contacted for information on fishermen settlements in the project area that might be affected
by the Sethusamudram Ship Canal Project. Based on the information obtained, the following
areas were visited for personal/group interviews on the ‘Socio-economic Component’ of the
project. This survey represents a sample of 8000 to 10,000 fishermen from Pamban,
Natarajapuram, Ramakrishnapura, Kothandaramar Koil Nagar (near the temple) and Moonru
Eruppu Chathram in the study area.
Natarajapuram, a village on the way to Kothandaramar Temple, is situated at a
distance of about 6 km from Rameswaram. The population of the village is about 4000, and
fishing is the only occupation of the villagers. There is a Registered Fishermen Co-operative
Society with Shri Chelladurai as the President of the Society. About 100 numbers of Vallam
(non mechanized boat with outboard motors of less than 14 H.P.) are used for fishing per day.
Each Vallam is manned by 5 people and so about 500 people are engaged in fishing per day.
Since these villagers are dependent upon non-mechanized boats (Vallam) they can go for
fishing only upto 3 km from the shore. The fish landing area of these people comprises the
shallow waters in the vicinity of the shore. Eral, nethil varieties are more only in the
Northern side and especially during June, July and August.

Nearly 25 people belonging to the fishing group were interviewed for their views
about the Sethusamudram Ship Canal Project, popularly known among the local people as
“Sethu Calvai Thittam”. For the past 100 years the Government of India/ Tamil Naud have
been talking about the project, and therefore, the people in this area are well aware of the
project. The residents of Natarajapuram village were originally living in Dhanushkody
island. When Dhanushkody was engulfed by the severe cyclone of 1964, these people shifted
their residence to Natarajapuram. A large number of them are occupying Government land,
and have not been issued ‘pattas’ because of the proposed ‘Sethu Calvai Thittam’. Even
though the Government has the intention to issue pattas to these people, it is not able to do so
as the area required for the Sethu Calvai has not yet been identified and earmarked. Under
these circumstances, the people of Natarajapuram village anxiously look forward to the
fruition of the project at an early date, so that they will get the pattas for their lands. The
people are in one voice in favour of the Sethu Calvai Thittam.
Ramakrishnapuram village is in the vicinity of the proposed alignment of the
Sethusamudram Ship Canal. There is a Fishermen Co-operative Society in this village. As
per Shri Kumaresan, the President of the Society, there are 1432 registered mechanized
boats on both the islands. Out of these on an average 750 boats are used in a day for fishing
operations in the islands. Since these people use mechanized boats (upto a H.P. of 114) they
go for deep sea fishing thrice a week. The peak season lasts 5 months in a year. Here also
the people are well aware of the project because of the century old propaganda by the elected
representatives about implementing the project. While the people welcome the project, they
have an apprehension that deepening the canal might result in a reduction in the fishery
potential leading to a direct impact on the fishermen’s economic development. They also
expressed concern that their fishing nets could be damaged during ship navigation when the
canal comes into being. The fishermen suggested that, if the project comes into operation,
they need a separate boat jetty in a convenient place to anchor their boats. Not withstanding
the above, they all are in favour of the project.
The settlement called ‘Kothandaramar Koil Nagar’ near the Kothandaramar temple
has about 200 huts with a population of nearly 800. This village is very near the proposed
alignment and the local fisher folk have no ‘Vallarns’ or ‘Thonis’ for fishing. They go for
fishing to the Dhanushkody island by bus/walk. According to them fish is available in the
shallow (2 to 3 feet) waters in the Dhanushkody island. The fish catch is transported to the

market by bus or as head loads. When interviewed, the people were of the opinion that the
Sethu Canal project would severely affect their economic development. The proposed land
cutting for the navigation channel between Kothandaramar Koi and Dhanushkody island,
near ‘Moonru Eruppu Chathram’, will cut off the road transport facility between their
dwelling places and Dhanushkody island, their only place of fishing. None the less, they are
in favour of the project in the overall national interest and with the hope that they will get
their ‘pattas’ from the Government once the project comes into operation.
The Government of Tamilnadu permits fishing by licensed fishermen in the islands
throughout the year. There seems to be competition between the fishermen having
mechanized boats on one hand and non-mechanized boats on the other resulting in over
exploitation of fishing in both the islands. Since the Sri Lankan Government has banned the
fishing operation for three months in a year, a sustainable fish potential is maintained near
‘Kachcha Thivu’ just two kms beyond the International Border Line (IBL) between India and
Sri Lanka. The over exploitation of fishing in the Indian islands tempts the Indian fishermen
to cross the IBL and get involved in fatal accidents by Sri Lankan Naval Staff. Under these
circumstances, the Sethu Samudram Ship Canal Project may not have any direct adverse
impact on fishing potential in both the islands.
The Naval Staff of the Coast Guard Station at Mandapam are of the view that the
implementation of the project will increase the potential for oil spill in the navigation canal.
They also suggested that the above problem could be overcome by enanting a low by which
any ship navigating through the canal and causing oil spill would not be allowed to use the
canal in future. Otherwise, they are much in favour of the project as it would provide free
protected access to fisherman between the Gulf of Mannar and the Palk Bay, illegal and
clandestine activities in the project area and also improve the socio-economic status of the
people living in Ramanathapuram, Rameswaram, Mandapam and Tuticorin.
Some of the Government staff directly involved in R&D in the Gulf of
Mannar and the Palk Bay were of the opinion that currently the increased activities in
both the Gulf of Mannar and Palk Bay have been depleting the reserves of the 'Bio-
Paradise of the Gulf of Mannar'. They further observed that there were more of dead
coral reefs than live ones. Under these circumstances, the proposed project with the
canal alignment far away from the marine parks (islands) would not have any

significant adverse impact on the bio-sphere reserves of the Gulf of Mannar. They
also are in favour of the project.
5.3 Existing Status
The entire GOMBR area comprises of 99 panchayats spread over
approximately 1600 sq. km area. The area has around 466 villages, varying in size
and population. A population of around 2.79 lakhs live in the area depending on the
sea, agricultural and allied livelihoods.

The Sub-programme Area and the Households:
Name of the Block No. of No. of Total Total
Panchayats Villages households Population
Ramnathpuram
District
Mandapam 22 146 15,930 74648
Thirupulani 22 130 11,038 53554
Kadaladi 25 100 20,385 80855
Ramnad 3 22 3,241 14707
Tuticorin District
Vilathikulam 20 50 7,843 35193
Ottapidaram 7 18 4,450 20274
Total 99 466 62,887 279231
(Source : Compilation from Census 1991)
The socio-economic development of the region is poor and requires intensive
efforts for developing it. The reserve area as demarcated is predominantly dependent
upon sea based activities which includes fishing and salt making. There however,
exist opportunities for palm-based occupations and other incidental activities related to
fishing. Agriculturally the area is characterized by severe drought with agriculture
dependant on the monsoons. The yields of crops are generally low and risk-prone due
to complete absence of irrigation facilities. The major source of irrigation is through the
village tanks, which are solely dependent upon the rainfall. The existing sea based
resources have become constrained and prone to conflicts and forcing the people in
the reserve area into despair.
Conflicts between intensive and artisanal fishers regarding equitable
access to marine resources: The mode of fishing in the reserve area is through
traditional fishing through catamarans and mechanised trawlers. There are many
instances of conflicts between these two sectors, namely the traditional and
mechanised sectors on the one hand, and also within the sectors, on the other,
because of unequal opportunities. These lead to violent clashes in the open sea,
cutting of nets setting boats on fire. The mechanised boats, which allegedly cross the
international boundary line are often exposed to gunfire from the other side leading to
loss of life and seizure of boats.
The conflicts that arise in the fisheries sector are essentially due to the
economic disparity that has developed between the fishermen who continue to use the
age-old traditional crafts and gear to catch fish and the mechanised boat owners who

have been able to adopt and invest in modern technologies such as trawling. Artisinal
fishers have a narrow range of operations closer to the coastline with propulsion
depending on human muscle power and wind energy and passive gears where the
fish should reach the gear for capture. The mechanised boat owners have a longer
range for capture and operations away from the coastline and operate active fishing
gear which goes after the fish for capture.
This latter group goes for high value shrimps and fish and, because of their
efficiency cause problems for conservation of the target resources. Due to shrinking
economic returns, the former (artisanal fishermen), unable to meet their daily livelihood
needs, resort to unsustainable activities such as coral mining, dynamite fishing,
juvenile fishing, sea cucumber collection, intensive seaweed harvesting, and even
attack protected and endangered species. They thus come into conflict with the law
enforcement machinery.
Almost every fishing village has a Fishermen Co-operative Society; some
have more than one. There are also Fisher Women Co-operative Societies in most of
the villages. Every fisherman is a member of a society. The main function of these
societies seems to be implementation of government welfare and subsidy schemes for
the fishing community. Marketing is left entirely to the merchants/ middlemen/ agents
and auctioneers. In some cases fisherwomen undertake retail marketing.
The Department of Fisheries plays an important role in dealing with issues
related to fishing, regulations, conflict resolutions and welfare schemes. However, the
content and character of marine fisheries have changed a great deal since the advent
of mechanisation as also the opening up of export market for several of the marine
products. On the one hand, the present marine resource use is becoming more and
more unsustainable and, on the other, the livelihood security of traditional fishermen is
getting eroded due to diminishing income. In such a trend, conflicts are bound to
increase and become widespread.
Marine-based livelihoods: The livelihoods of people in the coastal buffer
zone partly depend on coastal and marine resources. However, agriculture and allied
activities still play a major role in providing livelihoods for the poor. The activities of
coastal-based people include fishing, salt making, seaweed collection or other marine-
based activities are gaining importance. Ninety percent of these fisherfolk are artisanal

(using wind or small engine powered craft) and 10% are mechanized trawler
fishermen. (Source: Paragraph 8 of GEF project brief)
The mechanisation of fishery has displaced women from their traditional roles
in processing, marketing and making of nets; forcing them to take up alternative
livelihoods. As women play a major role in supporting the sector, they would be the
primary beneficiaries. Existing livelihoods related programmes in the buffer zone area
do not provide adequate economic alternatives and in particular do adequately
address the needs of women fisher-folk. As a result, people’s only alternative
livelihood option has been harvesting of wild seaweed or coral, which they have been
over harvesting. (Source: Paragraph 9 of GEF project brief)
As a result of the complexity of the types and efficiency of fishing craft and
gear and the fluctuations in the available fishery resources, there are wide variations in
the catch and income to the fishermen. More than 70% of the active fishermen work as
labourers in the boats owned by others on share-basis or for wages. The fishermen
working in the country crafts such as catamarans, vathai, thoni and vallam (not
motorized) earn a daily income in the range of Rs.20-30, except on a few days during
the peak fishing season.
The fisherwomen are more burdened and try to supplement the family income
through fishery related trades such as dry fish preparation and marketing, seaweed
collection and net-making and mending, and non-fishery activities such as working as
labour in salt pans, and beedi making. These activities are seasonal and possible only
in certain areas and do not add much to the family income.
The GOMBR coastal belt has a very large proportion of country crafts, about
87%, against the mechanised boats, about 13%, in the total crafts of about 1573. Thus
a very large segment of traditional fishermen population has to work closer to the
shoreline in shallow waters where the resources are poor and thereby their income also
is poor. There are increasing number of instances where, due to poor catches and
diminishing economic returns, the owners are selling the mechanized boats.
The fishermen and fisherwomen, during discussion, expressed the desire for
guiding them and training them in income generating vocations that will improve their
socio-economic conditions. In respect of fishery technological options, Fish

Aggregating Devices (FAD's) for men and net making/ mending and fish by-products
for women stand out significantly.
In addition to fishing many are involved in various supplementary activities for
their livelihoods viz., charcoal making, salt making, mat weaving, coir making and
agriculture and allied activities. Availability of timely and adequate credit from the
formal system and lack of support systems for marketing are the two main problems
faced by the people. The detailed discussions on the calculations are given in the
annexures.
Agriculture-based livelihoods: In the buffer zone area, agriculture also
plays an important role in the life of the people. The major part of agriculture thrives
based on the irrigation available through the village tanks. These tanks are traditional
water harvesting structures and provide ample scope for enhancing their existing
livelihoods if rehabilitated and maintained properly. As per the recent statistics (1994)
in the Ramnad region near the Reserve there exist around 71 tanks irrigating 3,750
ha. This constitutes around 21 % of the tankfed area near the Reserve. As the region
is devoid of any other form of agriculture, tanks irrigate around 80 % of the lands under
cultivation. Almost all the tanks in the reserve area are in need of rehabilitation.
On the other hand, it is also reported that farm workers from hinterlands
mainly tankfed agriculture farmers are leaving and joining as trawler workers. Though
this is a seasonal activity the trend seems to be on the increase. The major reason
attributed is due to lack of proper irrigation facilities like tanks, which are mostly under
disrepair in the region. Any meaningful development of the Reserve should also
include the development of tank irrigation and dependent agriculture.
Financial services for poor: Existing livelihood related programmes in the
buffer zone continue to ignore the development of sustainable alternatives. In a
majority of the cases, people would continue to be forced to seek credit from the
moneylenders at prohibitively high rates of interest, resulting in more pressure on the
resource to repay the interest.
Majority of the poor in this area depend on the indigenous systems and have
least access to formal institutions providing these services. Predominant among
savings systems include local chits, friends and relatives. People are involved in a
local practice called ‘Seimora’ (offering of money to relatives on a social function)

which involves outflow of funds. Though this practice is a socially accepted mutual
support system, people find it difficult to meet these commitments and depend on
money lenders.
A variety of local lending practices are in use and the interest rates range
from 5-10% per month. In case of small consumption and emergency loans, the rates
are as high as 10-20%. The formal financial institutions primarily rely on collateral and
the procedures are lengthy resulting in undue delay in sanctioning of loans. Even if
formal credit is available, banks provide credit only for selected economic activities,
while the poor need credit for both income generation and social security. In order to
sustain the economic activity and to insulate the liquidation of assets in times of
emergency, the poor require continuous line of credit support for small consumption
and emergency needs.
As the livelihood of the poor in this area depends on the sea, there is a high
risk of accidents and often leading to death of family members. This causes great set
back to the whole family and affects their livelihoods. Though government sponsored
social security schemes are in existence, this does not cover and reach all the needy
in time. Incomes earned are high in cases of the marine or coastal-based activities but
due to the problem of alcoholism, the income does not reach the family and is drained
out of the system, keeping the families in perpetual debt leading to poverty. The
programme related to building up financial services should also include insurance
against the risks due to death, sickness and other calamities.
Existing status of Fishing Activities in Rameshwaram
The survey team had held discussion with general secretary of fishermen
association at Rameshwaram. It is revealed that about 50000 fishermen are involved
in fishing operation at Rameshwaram including all the villages in Pamban Island.
Fishing is done in both Palk Bay and Gulf of Mannar. Some times fishermen go upto
Lankan waters as prawn fishing in Palk Bay is not conducive due to rocky base. It
was informed that fish catch in Palk Bay has decreased over last 10 years.
Approximately 900 boats operate from Rameshwaram on alternate days. The fishing
is done both by mechanised and non-mechanised boats. Prawn catch is 20-25
kg/boat whereas fish catch is 600 kg per boat.

Table 5.1
Summary of Coastal Villages/Towns in the Study Area
Sr. No. of Population Area (Ha) Number of Population
District/Taluka
No. Villages/ (1991 Density
Houses House-
Towns Census) (Range)
holds
District : Nagapattinam
1. Sirkali 8 48170 7874.46 10601 10776 2.97-17.26
2. Tharagamabadi 5 31324 3759.03 2811 2829 3.09-19.22
3. Nagapattinam 8 119442 11520.91 24105 24818 3.72-58.44
4. Vedaranyam 7 52523 6021.45 5442 5448 2.54-33.99
5. Thiruthuraipoondi 3 21997 2090.01 776 797 5.76-11.27
6. Nannilam 1 1225 311.48 265 266 3.93
Total population in Dist. (in 2000) (1487055)
District : Thanjavur
7. Pattukottai 14 36030 11386.44 7946 8034 0.56-22.01
8. Peravoorani 10 11349 3633.16 2202 2255 -
Total population in Dist. (in 2000) (2205375)
District : Pudukottai
9. Avudaiyar Kovil 17 49854 8664.38 9823 10003 0.05-21.54
Total Population in Dist. (in 2000) (1452269)
District : Ramanathapuram
10. Thiruvadanai 13 55626 7389.99 5567 5602 0.27-24.69
11. Mudukulathur 8 33379 13201.95 6549 6685 0.13-4.13
12. Ramanathapuram 22 137812 30651.39 22016 22073 0.5-29.84
13. Rameswaram 2 56522 624.92 4656 4688 52.36
Total Population in Dist. (in 2000) (1183321)
District : Tuticorin
14. Vilathikulam 2 9548 5024.3 1818 1854 0.51-1.07
15. Ottapidaram 2 6793 4118.61 1344 1358 0.78-2.65
16. Tuticorin 5 237419 20841.77 1157 1180 4.08-35.73
Table 5.2

Details of Coastal Towns/Villages in the Study Area
(Palk Bay)
Sl. Name of No. of House-
Taluk Population Area (Ha) Density
No. Viallage/Town Houses holds
District : Nagapattinam
1. Perunthottam Sirkali 4270 607.57 984 989 7.03
Pandaravadai
2. Pudupattinam Sirkali 7444 1530.28 1722 1756 4.04
3. Thandavakulam Sirkali 4130 1022.20 1059 1059 4.04
4. Vedankudi Sirkali 4646 1563.00 1022 1022 2.97
5. Thirumullaivasal Sirkali 11551 669.24 2299 2395 17.26
(Urban Panchayat)
6. Thennampattinam Sirkali 4138 784.33 898 914 5.28
7. Kilaiyur Sirkali 6643 896.76 1453 1477 7.41
8. Vanagiri Sirkali 5348 801.08 1164 1164 6.68
9. Kalamanathur Tharagambadi 2805 811.26 658 658 3.46
10 Marudampallam Tharagambadi 2802 502.16 617 617 5.58
11. Pillaiperumal Nallur Tharagambadi 2593 839.25 626 626 3.09
12. Manikkapangu Tharagambadi 4243 624.00 910 928 6.80
13. Taragambadi (Urban) Tharagambadi 18881 982.36 N.A. N.A. 19.22
14. Nagore Nagapattinam 970 - 211 211
15. Prathiba Ramapuram Nagapattinam 5779 1553.96 1315 1315 3.72
16. Thiruppundi Kilobotti Nagapattinam 4490 936.05 1136 1136 4.80
17. Therkupovur Nagapattinam 3600 660.94 864 864 5.85
18. Vilandawadevi Nagapattinam 5071 929.05 1164 1165 5.46
19. Vellankanni Nagapattinam 6155 428.24 1301 1301 14.37
20. Vettaikaran Iruppu Nagapattinam 6888 1168.82 1794 1795 7.96
21. Nagapattinam Nagapattinam 86489 5843.85 16320 17029 58.44
22. Kodiyakadu Vedaranyam 1762 694.71 384 384 2.54
(Kodikarai)
23. Kovilpattu Vedaranyam 2747 567.00 682 682 4.84
24. Vellapallam Vedaranyam 5311 937.17 1241 1243 5.67
25. Naluvedampatti Vedaranyam 4938 959.69 1217 1219 5.15
26. Pushpavanam Vedaranyam 5700 1370.31 1405 1407 4.16
(Contd…)

Table 5.2 (Contd…)
Taluk
Sl. Name of No. of House-
Population Area (Ha) Density
No. Viallage/Town Houses holds
27. Periyaguttagai Vedaranyam 2233 614.90 513 513 3.63
28. Vedaranyam Vedaranyam 29832 877.67 - - 33.99
29. Muthupet (Rural) Thiruthuraipoondi 18826 1670.45 11.27
30. Muthupet (Urban) Thiruthuraipoondi 421 73.12 111 111 5.76
31. Thuraikkadu Thiruthuraipoondi 2750 346.44 665 686 7.96
32. Panagudi Nannilam 1225 311.48 265 266 3.93
District : Thanjavur
33. Thambikku Pattukottai 2575 2531.2 623 623 0.68
Nallavankottai
Maravadakku
34. Thambikku Pattukottai 3522 1293.02 896 896 2.72
Nallavankottai
Vadakku
35. Thamarankottai Pattukottai 10277 2309.60 2433 2442 2.27
36. Palanjur Pattukottai 2092 1476.20 494 494 1.42
.37. Adirampattinam Pattukottai 1591 987.40 241 241 1.51
38. Briparakkarai Pattukottai 2504 329.40 530 530 3.02
39. Vaullivayal Pattukottai 579 175.60 126 126 3.30
40. Sarabendiraravanp Pattukottai 4563 207.34 780 850 22.01
attinam
41. Rajamadam Pattukottai 2094 625.20 513 513 3.35
42. Kollukkadu Pattukottai 1795 505.00 368 368 3.48
43. Pudupattinam Pattukottai 1300 242.20 251 251 5.37
44. Andikkadu Pattukottai 1409 366.80 324 324 3.84
45. Kollivoyal Pattukottai 65 115.60 15 15 0.56
46. Karisavayal Pattukottai 1664 221.88 354 354 5.02
47. Rowthanvayal Peravoorani 793 129.48 128 128 -
48. Villunniyoyal Peravoorani 96 391.21 27 27 -
49. Adikadevan Peravoorani 611 335.221 27 27 -
50. Sendalaivayal Peravoorani 1167 186.14 212 212 -
51. Nadiyam Peravoorani 2093 707.82 454 454 -
52. Sedubavachattram Peravoorani 1225 94.10 237 237 -
53. Marakkavalasai Peravoorani 1443 404.31 286 286 -
(Contd...)

Table 5.2 (Contd...)
Taluk No. of House-
Sl. No. Name of Viallage/Town Population Area (Ha) Density
Houses holds
54. Ariyakuttithevan Peravoorani 24 115.09 5 5 -
55. Thiruvathevan Peravoorani 1922 725.16 410 417 -
56. Kuppathevan Peravoorani 1975 544.63 416 431 -
District : Pudukottai
57. Melastanam (3 part) Avudaiyar Kovil 246 386.96 56 56 0.64
58. Manamelkudi Avudaiyar Kovil 13627 1135.24 2705 2710 7.63
59. Kodikulam Avudaiyar Kovil 10737 1028.64 2178 2304 10.44
60. Kizhamanjakkudi Avudaiyar Kovil 2081 594.50 413 413 3.50
61. Nattanipurasakudi Avudaiyar Kovil 7719 916.21 1418 1436 8.42
62. Alaganvayal Avudaiyar Kovil 2627 238.45 498 498 11.02
63. Enadi Avudaiyar Kovil 298 331.53 63 63 0.90
64. Subrahmanyapuram Avudaiyar Kovil 3092 239.96 504 528 12.89
65. Revuthanvayal Avudaiyar Kovil 169 36.87 40 40 4.58
66. Pillaiyartidal Avudaiyar Kovil 295 168.37 69 69 1.75
67. Munpalai Avudaiyar Kovil 1616 873.69 312 312 1.85
68. Avadaiyarpattinam Avudaiyar Kovil 390 18.11 65 65 21.54
69. Thandalai Avudaiyar Kovil 1494 598.54 324 324 1.58
70. Periamadaipayachal Avudaiyar Kovil 2995 778.30 652 652 2.66
71. Seyyanam Avudaiyar Kovil 1203 761.35 239 239 1.58
72. Mimisal Avudaiyar Kovil 1244 124.74 282 289 9.97
73. Palangulam Avudaiyar Kovil 21 432.92 5 5 0.05
District : Ramanathapuram
74. Marungur Thiruvadanai 5221 564.78 924 924 -
75. Uppur Thiruvadanai 3574 670.85 713 713 4.46
76. Tiruppalaikudi Thiruvadanai 7078 286.63 1273 1273 24.69
77. Vattanam Thiruvadanai 1780 464.37 380 380 0.33
78. Muthuramalingapattinam Thiruvadanai 254 144.46 49 49 1.63
79. Valangudi Thiruvadanai 218 81.78 41 41 2.67
80. Pudupattinam Thiruvadanai 3641 115.38 674 705 11.08
81. Chitturuvadi Thiruvadanai 2145 589.88 472 472 3.64
82. Valamavur Thiruvadanai 384 273.66 79 79 0.27
83. Thondi Thiruvadanai 19240 1554.12 N.A. N.A. 12.38
(Contd...)

Table 5.2 (Contd…)
Taluk Population No. of House-
Sl No. Name of Village/Town Area (Ha) Density
Houses holds
84. Nambuthalai Thiruvadanai 6908 816.55 N.A. N.A. 8.46
85. Kaliyanaguri Thiruvadanai 1978 326.27 427 431 6.06
86. Kanathankundu Thiruvadanai 3205 1501.26 535 535 2.13
87. Mandapam Ramanathapuram 5709 2263.92 1145 1145 0.50
88. Devipattinam Ramanathapuram 8350 1520.79 1634 1658 5.02
89. Chittrakkottai Ramanathapuram 6667 2106.82 1331 1337 3.16
90. Theruvadi Ramanathapuram 5162 1054.97 899 899 2.82
91. Alagankukam Ramanathapuram 13364 2294.47 2636 2637 2.78
92. Attangarai Ramanathapuram 2854 814.76 601 616 3.50
93. Enmahamkundan Ramanathapuram 5159 481.17 1141 1151 10.72
94. Pirappanvalasai Ramanathapuram 3991 1070.61 918 918 2.40
95. Sattakkonvalasai Ramanathapuram 2108 1332.92 405 406 1.58
96. Nochivurani Ramanathapuram 2331 1305.20 550 550 0.57
97. Kalimankundu Ramanathapuram 5476 1190.04 1254 1254 2.09
98. Tiruppullani Ramanathapuram 6599 2929.02 1255 1255 0.63
99. Kanjirahgudi Ramanathapuram 5431 1586.48 1049 1049 3.42
100. Rameswaram rameswaram 32721 624.92 - - 52.36
Note : N.A. – Not Available

Table 5.3
Details of Coastal Towns Villages in the Study Area
Taluk
SI Name of No. of House-
Population Area (Ha) Density
No. Village/Town Houses holds
District : Ramanathapuram
1. Pudumadam Ramanathapuram 6940 783.19 1461 1461 8.86
2. Attiyuthu Ramanathapuram 2407 1162.58 445 445 2.07
3. Kilnagachchi Ramanathapuram 2328 954.12 502 502 2.44
4. Karan Ramanathapuram 3164 1231.40 693 693 1.73
5. Rettaiyurani Ramanathapuram 5446 1382.33 1300 1300 0.65
6. Periyapattinam Ramanathapuram 7762 931.75 1459 1459 6.63
7. Keelakarai Ramanathapuram 32834 2199.13 598 598 29.84
8. Mayakulam Ramanathapuram 3107 1374.12 601 601 2.26
9. Pattennedal Ramanathapuram 623 681.60 139 139 0.91
10. Pamban Ramanathapuram 23801 N.A. 4656 4688 N.A.
11. Kannirajapuram Mudukulathur 4139 1002.06 779 783 4.13
12. Narippaiyur Mudukulathur 6214 1798.07 1157 1178 3.46
13. Kudiraimoli Mudukulathur 637 262.84 136 136 2.42
14. Periyakulan Mudukulathur 5470 2898.76 1101 1122 0.13
15. Vallindokkam Mudukulathur 3482 1133.98 544 568 3.07
16. Ervadi Mudukulathur 7334 2300.95 1590 1644 3.19
17. Mukkaiyur Mudukulathur 1820 1766.33 333 336 0.66
18. Mariyur Mudukulathur 4283 2038.96 909 918 1.87
District : Tuticorin
19. Vembar Mudukulathur 5122 1323.35 918 940 1.07
20. Vaippar Mudukulathur 4426 3700.95 900 914 0.51
21. Kila Arasaid Ottapidaram 1368 1315.43 303 306 1.04
(Contd…)

Table 5.3 (Contd...)
Name of Village/Town Taluk
SI Population Area (Ha) No. of House- Density
No. Houses holds
22. Pattanamarudur Ottapidaram 838 1071.88 165 165 0.78
23. Taruvaikkulam Ottapidaram 4587 1728.30 876 887 2.65
24. Sankarapperi Tuticorin 5376 1317.94 1157 1180 4.08
25. Mullakkadu Tuticorin 2271 120.86 N.A. N.A. 18.79
26. Tuticorin (Rural + Town) Tuticorin 205766 17574.01 N.A. N.A. 15.63
27. Milavittan Tuticorin 10679 298.88 N.A. N.A. 35.73
28. Mappilaiurani Tuticorin 13327 1530.08 N.A. N.A. 8.71
Note : N.A. – Not Available
Source : Coastal Zone Management Plan for Tamil Nadu, Environmental &
Forest Department, June 1996
6. Assessment of
Environmental Impacts
6.1 General
The major step involved in the process of environmental impact assessment
is the identification of impacts as it leads to other steps such as quantification and
evaluation of impacts. In order to identify and evaluate the impacts associated with the
project, it is necessary to establish a general checklist and describe the existing
environmental quality in the area under development, and the activities of the
proposed project which may cause environmental impacts.
While a number of techniques are available for identification of impacts, in the
present case, the “Network Method” which involves understanding of the cause-

condition-effect relationship between an activity and environmental parameters has
been adopted. This method has been basically advantageous in recognizing the
impacts that would be triggered by the proposed activities and provides a “road map”
type of approach for the identification of second and third order effects. The purpose is
to account for the project activities and identify the type of impacts which would initially
occur. The next step is to select each impact and identify the secondary and tertiary
impacts which will be induced as a result. This process is repeated until all possible
impacts are identified. The major advantage of this approach is that it allows
identification of the impacts by selecting and tracing out the events as they are
expected to occur.
6.2 Impact Networks
In the backdrop of data collected during the site visits, information provided by
the concerned authorities and the list of project activities described earlier in the
report, the ‘cause-condition-effect’ networks for various components and activities of
the project have been delineated as depicted in Fig. 6.1 through 6.2. In these
illustrations, the lines are to be read as “has an effect on”.
Pre-construction activities are those taken up prior to start up of the actual
construction of the project and may include resettlement and rehabilitation. They may
not have any direct impact on environment as such but may lead to socio-economic
impacts on the local inhabitants who are likely to be displaced and relocated.
Construction activities would cause land alternations in accordance with the
project design and a variety of physical, chemical, ecological, aesthetic and socio-
economic impacts of varying duration and magnitude. Physico-chemical changes
occur mainly due to dredging, and clearing of vegetation cover at the site and
earthwork excavation thereby causing soil erosion resulting in turbidity in surface
runoff. Ecological impacts occur due to loss of marine resources, removal of trees and
shrubs and field habitats which result in destruction of terrestrial organisms. Socio-
economic impacts that occur during construction relate to generation of employment,
displacement of families, removal of natural resources of the site etc.
Operation phase involves various maritime and shipping activities all of which
can cause impacts (positive or negative) on marine water quality, ecology, aesthetics
and socio-economics of the project affected population.

6.3 Impacts due to Land Based Facilities
The project envisages construction of shore facilities to cater to needs of
canal in Adam’s Bridge area, viz. service jetties, slipways, buoy yard, repair workshop
as also staff and administration buildings for facilitating regulated traffic in the vicinity
of Adam’s bridge area. The locations of land-based structures, and the extent of area
required for their construction is required to be identified on Pamban island in
consultation with local authorities. Most of the land east of Rameshwaram is barren
and covered by sand and scant vegetation. There are few hamlets at Arimunai and
Dhanushkodi who are engaged in fishing. These fisherman will be displaced in the
event the land based facilities are planned in this area. Temporary displacement of
these fisherman is envisaged. A BSF check post will also be temporarily affected.
Land on Pamban island has also been identified for disposal of dredged material (silt /
clay / sand). The land cover, landuse as also the ownership of sites required for these
project related activities will be firmed up once the modus-operendi of traffic regulation
in canal portion is finalized. Hence, the extent of land acquisition, the need for
resettlement and rehabilitation of affected population, if any, could not be assessed at
this juncture. However, given that the canal will pass through Adam’s Bridge area, the
pressure on land based facilities would be negligible in comparison to that envisaged
in earlier studies where land locked canal cutting through Pumban Island was
proposed.
During the construction of the ship canal, it is anticipated that considerable
sea-borne activity in the form of logistic and support services would take place. This,
coupled with the dredging activity, would have significant adverse impact on the
traditional fishing activities by the licensed fisher folk and consequently on their income
levels.
6.4 Impacts due to Dredging
The major activity during construction phase of project comprises capital
dredging along the proposed alignment of the ship channel in Adam’s Bridge and Palk
strait area. The area which require intensive dredging to achieve depth of 12 m across
the Adam’s Bridge area is over a length of 20 km and in Palk Bay Strait area is about
54 km. The areas have been studied for its actual bathymetry, seabed characteristics
and hydrography.

The study area near the Adam’s Bridge is depicted in Fig. 6.3 and the
borehole data for this region has been collected in March 2004 and is show in
Fig. 6.4. Sediments of different grain sizes mainly consists of sand silt and clay. The
data is presented in Chapter 2 under geological strata. Bathymetry data computed for
5 different alignments in Adam’s Bridge area is shown in
Tables 6.1 to 6.5 and Figs. 6.5 to 6.9. Regressional coefficient for each graph was
computed to arrive at actual quantity of dredged material generation for 12.0 m depth
profile. The quantities of dredged material along each line are shown in Fig. 6.10.
Total area under dredging in Adam’s Bridge section for 12 m deep,
300 m wide channel will be about 600 ha. The quantity of capital dredge material
including slope and tolerance is approximately 38 x 106 m3 for 12 m deep channel.
Requirement of capital dredging in Palk Bay/Palk Strait area have been
computed. The proposed alignment in Palk Bay/Palk Strait is shown in Fig. 6.11. The
Bathymetry along the alignment is presented in Fig. 6.12. The quantity of dredged
material will be about 44 million m3 for 12 m deep 300 m wide channel as per
bathymetry data collected by National Hydrography office, Dehradun
(Fig. 6.12).
The proposal envisaged by Ministry of Shipping was for creation of navigation
channel to suit different draught requirement viz. 9.15, 10.7 and 12.8 m requiring
dredging depths of 10 m, 12 m and 14 m respectively. For 12.8 m draught channel
width will be 500 m whereas for 9.15 and 10.7 m draughts, channel width will be 300
m. Based on hydrography data collected by NHO
(Fig. 6.12) it is observed that navigation depths in Palk Bay are restricted to about 12
m only. The total length from Adam’s Bridge to Palk Strait is about 145 km. Based on
the bathymetry data, requirements of dredging and quantity of dredge spoil likely to be
generated have been computed for various options viz. 9.15 m draught (10 m deep),
10.7 m draught (12 m deep) and 12.8 m draught (14 m deep) channel with respective
widths. The data is provided in Tables 6.6-6.8. It could be observed that quantity of
dredged/spoil will reduce with the depths to about 39, 82 and 313 million m3
respectively besides reduction in length of channel to be dredged. In the event of
proposal for 12.8 m draught requiring 14 m depth, dredging will require to be carried
out in entire Palk Bay area to create a channel of 500 m width generating 313 million

m3 of dredge spoil. Dredging all along the length of the channel in Palk Bay will be
detrimental to ecologically sensitive area of this region. It would also involve heavy
additional expenditure on dredging and disposal of dredge spoil. Thus keeping in view
environmental sensitivity and economic viability the proposal for 14 m depth (12.8 m
draught) is not considered. Thus channel depth of only 10 m and 12 m are considered
for studying environmental and economic impacts. The channel will be dredged with a
bottom width of 300m to a depth of -10mCD or -12mCD in Palk Strait and adjoining
parts of Palk Bay to achieve the required depth over a stretch of 36 and 18km
respectively. In the Gulf of Mannar, navigational depths (more than 12 m) will be used
from Tuticorin Port to Adam’s Bridge Area. A 20 km long channel with a bed width of
300 m. will be dredged to a depth of -10mCD or -12 mCD catering to vessels drawing
a draught of 9.15 or 10.7m respectively.
Though option for both 9.15 m and 10.7 m draught were evaluated, study
carried out by shipping corporation of India for estimating traffic potential at 7, 9 and 11
draught recommended that a minimum draught of 10.7 m be kept to make channel
viable. The savings based on expected number of transits through proposed channel
for various considered draught is given in Table 6.9.
The proposed channel will have a bed width of 300m which will provide a safe
width for navigation of two way channel. The channel will have side slopes of 1:3. A
cross section of channel is shown in Fig. 6.13.
Besides capital dredging, annual maintenance dredging of about 0.1 million
3
m is envisaged in Adam’s Bridge area based on data available for sediment transport
across Palk Bay and Gulf of Mannar. The studies carried out by NSDRC signifies that
the region around Adam’s Bridge forms an significant sink for littoral drift. The
prolonged accumulation in this area may lead to emergence of new Island. In case of
occurrence of cyclone in Gulf of Mannar, such prolonged deposition of sediments
move north and enter Palk Bay through Pamban Pass and Adam’s Bridge. Once the
sediment enter Palk Bay, the environmental condition favours immediate deposition.
Hence the occurrence of cyclone in Gulf of Mannar and the associated northerly
waves might, exchange more sediment from southern part of Peninsular India to
Northern part of east coast. Thus the quantity of maintenance dredged spoil will
increase in the channel across Adam’s Bridge in the event of cyclone.

The dredging of sea bed would result in increase of turbidity due to silt & clay
both during dredging and disposal. Higher silt load in seawater prevents penetration of
sunlight in water body and ultimately affect primary productivity.

Primary productivity, the only means of synthesis of organic matter is the
basis to trophic web. Any damage to the lower trophic level would reflect into higher
trophic including fish. If sunlight does not penetrate into the sea for days together,
darkness would prevail on the bottom, which adversely affect the photosynthetic
activity of the symbiotic algae in the molluscs and corals. Further when silt gets
deposited on all living organism especially on sedentary biota - viz. pearl oysters,
corals, algae, gorgonids, other molluscs, annelids, prochordates, echinoderms, the
egg mass of many free swimming animals, etc, they get destroyed since these
organisms have no / little locomotive power to move away from the dredging zone.
Deposition of silt bury many small living organisms. Silt enters into the gills of the
animals and impairs respiration. Silt also affects the planktonic life. siltation affects the
solubility of oxygen and gas exchange due to mineralisation and pH changes and,
thus, the amount of dissolved oxygen in the water is reduced. Owing to the destruction
of seagrass and seaweed beds, larger animals such as dugongs, turtules and
herbivorous fishes are also affected. It is true that the dissolved components of the silt
would enrich the algal growth and trigger the planktonic bloom. But this blooming may
not be of much use since the benthic and other fauna, which mainly feed on them, are
either not available or destroyed owing to silt deposition.
It is known that seabed strata is only sand hard pane and blasting which
could adversely affect flora and fauna due to shock waves emanating from the blast is
not required for excavation/dredging.
Whatever may be the method of dredging that is employed, a part of
sediments removed from the sea bottom would get spread to adjacent dredging area.
This would form as a mat and bury the entire fauna and flora into it. Adverse effects
are also to be expected from pollution owing to the use of machinery for construction
and operating units. Spillage of oil and grease, rust and metallic wastes due to wear
and tear, marine litter, float, including plastic bags, discarded articles would be the
major pollutants.
To minimize impacts due to dredging and disposal of dredged material,
options for both land and sea disposal are considered. Suitable location on land as
well as in sea are to be selected based on environmental viability. Likely impacts due
to both the options are discussed in following section :

6.4.1 Dredged Material Disposal
6.4.1.1 Disposal on Land
Based on recent remote sensing imageries for landuse and landcover,
degraded areas in Pumban island have been identified (Plate IV referred in Chapter
4) for disposal of part quantities of dredged material. Visual inspection of the project
site has revealed that a long stretch in Pumbam island between Kodandaramasamy
temple and Dhanushkody could be one of the potential sites for dredged material
disposal. Based on the analysis and interpretation of satellite data under the present
study, a few sites including the above have been identified for land disposal of the
dredged material. The suitability of these sites has been confirmed after detailed
groundtruth verification of the sites. Composition of dredged material plays vital role in
deciding its suitability for disposal on land. The degraded areas identified in Pumban
island near Dhanushkody are sandy in nature. The dredged material has content of 5-
8% clay and silt hence the spoil can be used for nourishment of degraded land for
reclaiming it and promoting life and vegetative growth. However the site will require
proper embanking/protection to prevent erosion due to wave action during cyclonic
conditions.
Keeping in view the reduction in quantity of dredged material due to
realignment of route using navigational depths available in Gulf of Mannar, the
dredging activity will be restricted to an area in the vicinity of Adams Bridge over a
length of about 20 km and width of 300 m. The quantity of dredged spoil generated
upto a depth of 12 m is 38 million m3 in this area. It is proposed that the top protion of
the sea bed containing silt and clay (Approx. 7-8 million m3) be disposed on degraded
areas of Pamban Island subject to approval under CRZ. The rest of the dredged
material containing mainly sand with particle size varying from 125 µm to 600 µm is
proposed to be disposed into sea (Gulf of Mannar) at a location varying from 30-40 m
depth. The Plate IV referred in Chapter 4 shows proposed location for disposal of
dredged material as indicated in the marked area spreading over 753 hectares. The
area is degraded land and can be converted into cultivable land through nourishment
by dumping silt and clay with some portion of sand from dredged material.
The maintenance dredge spoil will mainly comprise silt / clay and will be used
for reclaiming degraded areas in the vicinity of Pamban island / Mandapam.

6.4.1.2 Disposal in Sea
Disposal of dredged spoil generated during capital dredging containing sand
is proposed to be disposed in sea in the proximity of dredging activity where potential
adequate dilution and dispersion is available. It is observed from the bathymetry data
that a depth of 30-40 m is available about 25-30 km away from Adam’s Bridge in GOM
area. An exercise using dispersion modelling was carried out to study impact of
dredged spoil on turbidity of sea water.
The Cornell Mixing Zone Expert System (CORMIX), evaluation version
represents a robust and versatile computerized methodology for predicting both the
qualitative features (e.g. flow classification) and the quantitative aspects (e.g. dilution
ratio, plume trajectory) of the hydrodynamic mixing processes resulting from different
discharge configurations and in all types of ambient water bodies, including small
streams, large rivers, lakes, reservoirs, estuaries, and coastal waters.
The methodology provides answers to questions that typically arise during the
application of mixing zone regulations for both conventional and toxic discharge. More
importantly, this is accomplished by utilizing the customary approaches often used in
evaluating and implementing mixing zones, thereby providing a common framework
for both applicants and regulatory personnel to arrive at a consensus view of the
available dilution and plume trajectory for the site and effluent discharge
characteristics.
Three different subsystems for discharge conditions are available in CORMIX.
The model predicts the geometry and dilution characteristics of the effluent flow
resulting from a submerged single port diffuser discharge, of arbitrary density
(positively, neutrally, or negatively buoyant) and arbitrary location and geometry, into
an ambient receiving water body that may be stagnant or flowing and have ambient
density stratification of different types.
To predict dilution and plume trajectory of discharged effluent, CORMIX
typically combines the solutions of several simple flow patterns to provide a complete
analysis from the efflux location all the way into the far field.
The logic processing elements of CORMIX identify which solutions should be
combined to provide the complete analysis. This process, called flow classification,

develops a generic qualitative description of the discharge flow and is based on known
relationships between flow patterns and certain calculated physical parameters.
PARAM is the program element that computes relevant physical parameters
including the various length scales, fluxes, and other values needed for the execution
of other program elements. Length scales are calculated measures of the length of
dynamic influence of various physical processes.
At the heart of CORMIX is a flow classification system contained in the
program element CLASS. It provides a rigorous and robust expert knowledge base
that carefully distinguishes among the many hydrodynamic flow patterns that a
discharge may exhibit. These possibilities include discharge plumes attaching to the
bottom, plumes vertically mixing due to instabilities in shallow water, plumes becoming
trapped internally due to density stratification, and plumes intruding upstream against
the ambient current due to buoyancy and many others. Theoretically based
hydrodynamic criteria using length scale analysis and empirical knowledge from
laboratory and field experimentation are applied in a systematic fashion to identify the
most appropriate flow classification for a particular analysis situation. For all three
subsystems, a total of about 80 generic flow configurations or classes can be
distinguished.
Once a flow has been classified, CORMIX assembles and executes a
sequence of appropriate hydrodynamic simulation modules in the program element
HYDRO1, 2 or 3. HYDRO consists of : (a) control programs or \"protocols\" for each
hydrodynamic flow classification and (b) a large number of subroutines or \"simulation
modules\" corresponding to the particular flow processes, and their associated spatial
regions, that occur within a given flow classification. The simulation modules are
based on buoyant jet similarity theory, buoyant jet integral models, ambient diffusion
theory and stratified flow theory, and on simple dimensional analysis. The basic tenet
of the simulation methodology is to arrange a sequence of relatively simple simulation
modules which, when executed together, predict the trajectory and dilution
characteristics of a complex flow. Each of the simulation models uses the final values
of the previous module as initial conditions.
For simulating discharge of dredge material in sea (tentative location shown
in Fig. 6.14a), single submerged port discharge is used for predicting the movement of

suspended solids (Silt) in the ocean. Table 6.10 shows the calculation of silt produced
during dredging operation and its concentration in the discharged water. The scenario
is generated for steady state discharge of silty water having a concentration of
1,20,000 mg/l. The flow rate is taken to be 1.099 m3/s. The density of the discharged
water is taken to be 1047 kg/m3 and the effluent is discharged having discharge depth
of 25 m. The ambient water body is sea in which the effluent is discharged and is
taken to be unbounded. The wave currents or velocity are taken to be 0.3 m/s and
surface wind velocity have been taken as 5 m/s. Fig. 6.14 shows the three-
dimensional plume showing the movement of suspended solids (Silt). Fig. 6.15 shows
the variation of the Centerline Concentration along the direction of ambient current
velocity for Near Field and Fig. 6.16 shows for Far Field. Fig. 6.17 shows the dilution
vs. centerline distance. It can be inferred from these graphs that the effect of the silty
water when discharged will be localized and restricted to about 1500 meter from the
discharge point. However the plume will not surface immediately and the
concentration of suspended solids in sea water will return to normal after 1500 m in
the line of advection.
The capital dredging envisaged in Palk Strait area is 44 million m3 over a
stretch of about 54 km including some portion in Palk Bay in proximity to shallow areas
in Palk Strait. The quality of dredge spoil has been studied by NHO Dehradun.
Depending on the quality, disposal options can be decided. In the event of higher silt
content land disposal in proximity to dredging area avoiding sensitive locations viz.
Point Calimer sanctuary will be thought off. As this area is close to Bay of Bengal
where depth more than 25 m is available, disposal in sea would be a preferred option.
However concerns of transboundary migration of sand and pollutant will govern the
selection of site. The tracer studies have been initiated for further studies to select
suitable location. In no case dredged spoil will be allowed to be dispersed in Palk Bay.
Thus impact due to dredge disposal could be minimized by selecting option of
land disposal for dredged spoil containing higher percentage of clay and silt. Balance
dredged spoil containing sand could be disposed in sea. As sand particles have
discrete setting, rise in turbidity of sea water at disposal location is not envisaged
thereby minimizing impact on primary production. In the event of disposal of silt
containing dredged spoil the turbidity zone will develop at the disposal location,
however submerged disposal will not allow suspended solids plume to rise to surface

immediately thereby providing adequate dilution before the plume surfaces in the
direction of current. However by the time the plume surfaces at about 1500 m,
concentration of suspended solids would return to background level.
The existing level of primary productivity in the project area will remain
practically unaltered during the construction and operation phases of the ship channel
as proposal for disposal of silt / clay on land should be the most preferred option. Even
during sea disposal care would be taken to dispose material well below the sea
surface so that plume of suspended solids will remain submerged and will not cause
alteration in surface turbidity and primary productivity. There would not be any
significant change in water quality including turbidity due to the proposed deployment
of trailor suction hopper dredgers for capital and maintenance dredging. Moreover, the
envisaged dredging activities in the area are likely to cause much less turbidity than
the international threshold, and thus the likely risk to marine biota is going to be
minimal.
Disposal of sand (~30 million m3) in the form of dredge spoil will temporarily
after the structure of benthic community. However the benthos will restructure and
recover to original status after the capital dredging activity is completed.
Due to dredging, the bottom flora and fauna on an area approximately
600 ha along the channel alignment in Adam’s Bridge will be lost permanently. This
loss, however, will be very insignificant compared to the total area of 10,500 sq.km of
the Gulf of Mannar Marine Biosphere Reserves.
6.5 Impacts due to Road and Rail Traffic
During the construction activity viz. creating infrastructure base on Pamban
island to support dredging activity, the shore-based structures, there will be
considerable increase in rail and road traffic to and from the island for transportation of
men, material, machinery and equipment. These would inevitably lead to congestion in
traffic and increased levels of air and noise pollution with their associated impact on
normal public life. This scenario may continue during the operation phase of the canal
due to increased trade and commerce.
6.6 Impacts on Productivity and Ecology in
GOM/Palk Bay

As the proposed alignment in Gulf of Mannar is more than 20 km away from
the existing 21 islands in National Marine Parks in the Gulf of Mannar, the marine
biological resources around these islands will not be affected to any significant level.
The existing level of primary productivity in the project area will remain
practically unaltered during the construction and operation phases of the channel.
There would not be any significant change in water quality including turbidity due to
the proposed deployment of cutter suction/trailor suction hopper dredgers for capital
and maintenance dredging.
Due to dredging the bottom flora and fauna on an area about 6 sq. km along
the channel alignment in Adams Bridge and about 16-17 sq.km in Palk Bay/Palk Strait
area will be lost permanently. This loss, however, will be very insignificant compared to
the total area of 10,500 sq. km of the Gulf of Mannar Marine Biosphere Reserve.
In Adam’s Bridge area about 38 million m3 of dredge spoil comprising about
7-8 million m3 clay silt will be generated for achieving 12 m depth for 300 m wide
channel including allowances for slope and tolerance. It is proposed that spoil
containing a mixture of clay and sand will be disposed on degraded areas of Pamban
island for reclaiming the land subject to approval of Forest and Environment
Department (TN) for use of area falling under CRZ as dumping of wastes in CRZ area
is not permissible activity. Balance 30 million m3 spoil containing mainly sand (particle
size 125 µm to 600 µm) will be discharged in sea 25 km away from the dredging area
keeping safe distance from medial line at depths varying from 30-40 m to minimise the
impact. In the event of restricting the channel to 10 m depth to suit vessels with 9.15 m
draught, the quantity of dredged spoil will reduce by 13.5 million m3 and material
required to be disposed in sea will be 16-17 million m3 instead of 30 million m3 as
envisaged for 12 m depth. This would further minimize impacts on sea bed due to
disposal of dredged spoil.
In Palk Bay area, about 44 million m3 of dredged spoil will be generated due
to excavation activity in Palk strait and Palk Bay to achieve 12 m depth for 300 m
channel including allowances for slope and tolerance. The NHO data indicate hard
strata beneth soft sand hence spoil may contain silt, sand and hard material. The
dredging may also require blasting if hard strata is encountered. In the event of
blasting, adverse impact on sea bottom fauna is envisaged. The spoil is proposed to

be discharged in Bay of Bengal at suitable depth (25-40 m) to minimize impacts on
coastal areas of Palk Bay. An option of using silt/clay for beach nourishment is also
recommended. In the event of restricting the channel depth to 10 m the requirement of
dredging in Palk Bay/Palk strait will drastically reduce to about 14.8 million m3 as
against 44 million m3 envisaged for 12 m depth. This would minimize environmental
impacts as well cost of dredging and disposal.
It would be ideal to explore the possibility of dredging the channel to 10 m
depth in first phase to cater to vessels of 9.15 m draught and monitor environmental
status during construction and operation phases. The proposal of 12.0 m depth can
subsequently be taken up in second phase provided adverse impacts on environment
are not observed.
During the construction and operation phases of the channel, the potential
sources of marine pollution are spillage of oil and grease, marine litter, jetsam and
floatsam including plastic bags, discarded articles of human use from the sea-borne
vessels which will have to be controlled.
The channel will facilitate the movement of fishes and other biota from the
Bay of Bengal to the Indian Ocean and vice versa. By this way, the entry of oceanic
and alien species into the Palk Bay and the Gulf of Mannar, as also the dispersal of
endemic species outside the Palk Bay and the Gulf of Mannar could occur.
A potential source of pollution of the marine environment during the operation
phase of the project relates to ship discharges – oily ballast, bilge water and sewage,
and accidental spills. Likewise, the effects of anti-fouling paints on bottom dwelling
marine organisms, particularly clams and oysters, when the depth is relatively shallow
and there are a number of crafts moored in the location, can be significant.
Presently, stray turtles and marine mammals suffer from propeller cuts, ghost
fishing, and death due to ingestion of jetsam and floatsam. Such instances may
increase unless strict control is enforced in maintaining the canal litter-free, and
shipping speed is under regulatory control.
Despite significant shipping activities, it has been reported that Olive Ridley
turtles from the deep seas migrate to Gahirmatha beach in northern Orissa via
northern Sri Lanka and Paradeep Port for mass nesting during November-February
each year. Reported mass killing of turtles in this region is primarily due to their getting

entangled in gill netters and also due to poaching by local people for turtle flesh. This
observation indicates that the proposed canal project may not have any significant
adverse impact on the migration and mass nesting of turtles.
During the operational phase, the frequent ship movements in the channel,
maintenance dredging of the canal which could increase turbidity, oil spill, bilge water,
marine litter etc. may have negative impacts if they are allowed to travel to the Gulf of
Mannar Biosphere Reserve which supports a very fragile ecosystem.
Excavation of the channel in the Adams Bridge sector would provide a deeper
passage in the sector, which is shallow at present, and serve only as a barrier.
Underwater currents play a significant role, not only in the transportation of large
marine organisms, plankton biota, fish eggs and larvae but also on shore dynamics,
especially of the islands, reef and paars. Strong current would erode the banks of the
canal and carry the sediments from one sector to another, which ultimately results in
accretion of sand in one sector and erosion in another sector. Once the canal is
deepened, the passage would greatly increase the movement of fishes and other large
animals from Bay of Bengal to Indian Ocean and vice-versa. Hence, the entry of
oceanic and alien species into Palk Bay and Gulf of Mannar and also dispersal of
endemic species outside Palk Bay and Gulf of Mannar would be facilitated.
6.7 Impacts on Hydrodynamic Conditions
Because of the deepening of the channel, the course of water currents and
their speed as related to the prevalent biomonsoonal conditions may be altered.
Currents play a vital role not only in the movement of large marine organisms,
planktonic biota, the juvenile, larvae and eggs, but also on shore dynamics especially
of islands, reefs and paars. Current related sediment transport might level up, bury or
elevate certain locations, and yet other benthic sites may be eroded and deepended.
This would play havoc on the benthic animals including pearl oysters.
Hydrodynamic modelling was carried out to study the baseline spatial tidal
current distributions in the Gulf of Mannar and the Palk Bay, and to estimate the
changes that could be brought about due to the proposed ship navigation canal. The
focus has been to predict the change in direction and magnitude of the vector currents
due to the change (increase) in bathymetry resulting from dredging. The geographical

domain considered for modelling is shown in
Fig. 6.18.
A two dimensional (Ocean) Model, DIVAST (Depth Integrated Velocity and
Solute Transport) has been used for the hydrodynamic modelling. The model
simulates two dimensional distributions of currents, water surface elevations and
various water quality parameters within the modelling domain as function of time
taking into account the hydraulic characteristics governed by the bed topography,
surface wind effects and boundary conditions. It is assumed that the flow (in the study
region) is predominantly horizontal and nonstratified, and hence the two dimensional
depth integrated representation of the system is adequate. The solute transport
processes viz. advection, diffusion and dispersion are included. The temperature
distribution is taken to be governed by air-water heat exchange.
The finite different scheme used in DIVAST is based on the Alternating
Direction Implicit Technique which involves the sub-division of each time step into two,
for obtaining solutions in X and Y directions separately, using Gauss elimination and
back substitution methods.
The boundaries due to coastline or adjacent to structures are treated through
closed boundaries conditions and water surface elevations are treated through open
boundary conditions. The numerical treatment of flooding and drying in the tidal base
is incorporated through iterative checks on the wet and dry cells. The numerical model
allows for variable grid sizes in different zones allowing for better representation of
discontinuities in the neighbourhood of locations of interest.
6.7.1 Tidal Current Distributions - Before and After Dredging
The modelling exercise has been carried out on a HP Workstation under HP-
UNIX 10.1 Operating System. The source code of the model has been suitably
compiled, and configured for modelling, after incorporating boundary conditions. The
simulations have been carried out for 42 hours, for each case of ‘before dredging’ and
‘after dredging’ conditions.
The present bathymetry is assumed to be not significantly different from the
bathymetry data depicted in Naval Chart 317. For the purpose of model mapping, the
bathymetry data was interpolated for the entire modelling domain in grid sizes of 358
m x 358 m.

Current (tidal stream) measurements, with the assistance of the staff of Chief
Hydrographic Surveyor of India, were carried out at 10 locations in the study domain
for spring tide conditions. The locations, and their latitudes and longitudes are shown
in Fig. 6.19. The current measurements at a few representative locations in the Palk
Bay and the Gulf of Mannar are depicted graphically in Figs. 6.20 - 6.21. The graphs
depict the relative intensities of currents and directions and their variations over the
tidal curve. The values of maximum speed at a few locations in the Palk Bay and the
Gulf of Mannar are given in Table 6.11. The tidal variations with respect to time
measured at a location close to Rameswaram Jetty are shown in Fig. 6.22. The
proposed ship navigation alignment considered for modelling is shown in Fig. 6.23.
The depth, width and draft along the proposed alignment for modelling the
hydrodynamic conditions is taken as 12 m, 300 m and 10.7 m respectively.
The model has been calibrated and the calibration curves for tide and
currents are shown in Figs. 6.24-6.25. The curves show good match between the
measured and the model predicted values. The spatial distributions of tidal currents
have been modelled for two conditions :
i) with the present bathymetry
ii) with the increased depths along the proposed alignment
The currents predicted by the model for a new patches (sub areas) within the
study domain are shown in Figs. 6.26-6.27. The sub areas are chosen for being
geographically close to the coral reefs and the proposed alignment. The sub areas are
referred as Patch I, Patch II, Patch III and Patch IV in the Figs. 6.24-6.25. The
magnitudes and angles of the current vectors for each sub area are given in Table
6.12 through 6.15. The directions are with respect to the model axis. The model axis is
assumed to be North-South direction and the angles (in degrees) are measured in
clock wise direction from the model axis starting from North.
The arrows on the tidal curves in Figs. 6.24-6.25 indicate the time point on
the tidal curve for which the current vectors are shown.
Patch I is spatially located close to the coral reefs which are shown in Figs.
6.28-6.29 (Source of Data-Digitized from SAC Maps). It is seen that there is no
significant change in the magnitude and direction of current velocities.

Patch II and Patch III are close to the alignment in the South Approach
Channel in the Gulf of Mannar. As in the case of Patch I, it is seen that there is no
significant change in the magnitude and directions of current velocities.
Patch IV is in the Palk Bay close to the approach channel. There is a
significant change in magnitude and direction of current velocities near the proposed
alignment. However, west of the proposed alignment the directions remain the same.
6.7.2 The Salient Conclusions
Current vectors predicted by the model at the sensitive sub areas for highest
spring water height point out the following :
6.7.2.1 Gulf of Mannar
• There is no significant change in the current vectors due to dredging
• The current directions remain nearly the same after dredging
The average current direction is between 270O–350O, with respect to
-
model axis, and geographically this represents approximately North-
West direction (Model axis is South-North Direction, same as
geographical South-North)
• The maximum current speed is 0.7 m/sec
• Speed and directions do not vary significantly with geographical locations
close to the proposed alignment
6.7.2.2 Palk Bay (Near Adams Bridge)
For the sub region close to approach to the Channel from Palk Bay :
• There is a significant change in magnitude and directions for major portions
near the proposed alignment
Average direction before dredging is between 270o to 340o, towards
-
North-West
- The current directions in the channel alignment change due to dredging.
Average direction after dredging is 90O to 180O towards South-East
• However, to the west of proposed alignment there is no significant change in
current directions

• The maximum current observed is 0.31 m/sec

6.8 Socio-economic Impact
The channel will establish a continuous navigable sea route around
peninsular coast within the Indian territorial waters, reduce shipping distance by about
400 nautical miles and voyage time of about 36 hrs as also the attendant operating
costs. The channel will become a valuable asset from national defence and security
point of view enabling easier and quicker access between the coasts.
During the construction of the channel, the land access now available to the
local fisher folk to Dhanushkody area for traditional fishing will be hindered unless
alternative arrangements are made. The dredging and shipping operations will have to
be so regulated as to cause minimum disturbance to the normal fishing activities.
The project will provide employment opportunities and avenues of additional
income through establishment of small ancillary industries. The project will also trigger
development of coastal trade between the ports south and north of Rameshwaram
consequently reducing the load and congestion on railways and roadways.
Once the channel is in place the clandestine and illegal activities presently in
vogue in the Palk Bay and the Gulf of Mannar will be minimised due to constant
vigilance and regulation of movement of ships and vessels.
6.9 Analysis of Alternatives for Route Alignment
The various proposals considered for the alignment of the Sethusamudram
Ship Canal including the one recommended as a channel in current study are depicted
in Fig. 6.30. Between 1860 and 1922, as many as 9 proposals were formulated to
connect the Gulf of Mannar with the Palk Bay in order to shorten the sea route
between the west and east coasts of India. Most of these proposals envisaged cutting
through Pamban Channel. But none of these materalised for want of financial
resources.
After independence, the Government of India in 1955 constituted the
Sethusamudram Project Committee under the Chairmanship of Sir A. Ramaswamy
Mudalidar. The Committee made detailed investigations and recommended a crossing
through the mainland in keeping with the following : i) the site is directly in line
between Tuticorin and Palk straight, ii) the sea rout will be entirely west of medial line,
iii) this will obviate the use of vulnerable railway bridge at Pamban, iv) this alignment is

set to have little sign of hard material and v) scope for development due to its location
in main land is more. The Committee further recommended the implementation of both
the Tuticorin Port and Sethusamudram Canal as an integrated project. However, the
Government sanctioned only the Tuticorin project.
A high level Committee under the chairmanship of (late) Venkateswaram
appointed by the Government of India conducted further investigations and submitted
its report in 1968 recommending an alignment across the Rameswaram island in
keeping with the following advantages : i) short crossings requiring less length of
pilotage, and so less cost of pilotage, ii) quick transit of ships due to shorter length of
channels, iii) greater number of ships can be handled, iv) less maintenance dredging
of channels as the length of three channels is only 8 miles for this crossing as against
28 miles for the mainland crossing and v) no reef in this alignment of south approach
channel while the south approach channel of Mandapam alignment has reef which is
very difficult to dredge. The technical Committee, based primarily on cost and
economic considerations, recommended the Rameswaram alignment (DE alignment)
with an estimated cost of Rs. 37.46 crores for detailed investigation to cover all
seasons w.r.t. tide littoral drift etc. The proposal was reviewed from time to time and
the cost was updated in 1980 to Rs. 110 crores.
The Laxminarayanan Committee, constituted in 1981 by the GoI, reviewed
the above proposal and, on detailed inspection, noted that there was heavily built up
residential area in the Rameswaram alignment. It examined an alternative alignment
across Dhanushkody east of Rameswaram temple. After a study of the coastal
morphology in relation to the latest hydrographic chart, the Committee recommended
the K-alignment across Dhanushkody west of Kodandaramaswamy Koil with an
estimated project cost of Rs. 282 crores (1983 prices). For the same alignment and
associated quantities of work, the proposal has been updated for its economic viability
by PTCS Ltd. in March 1996.
In all the proposals listed as above, the only major criterion influencing the
final recommendation has been the economic viability of the proposal with very little
consideration to the environmental/economical aspects of the project. This can be
attributed to the fact that at that time even at the national level environmental concerns
of developmental projects were rarely addressed.

While detailed information for the above enumerated alternatives are not
available, it would be apparent that any alignment of the proposed canal across the
main land would have not only proved expensive due to the longer lengths of dredging
and the associated socio-economic impacts particularly with respect to land
acquisition, resettlement and rehabilitation. These alignments would have also been
nearer to the 21 islands in the Gulf of Mannar (which have subsequently been
declared as national Marine Parks) with their associated ecological impacts.
The alignment proposed by the Venkateswaran Committee also suffers from
similar problems as above, though relatively less in magnitude. The K alignment
crossing the Rameswaram island cutting a land portion of only 800 m involves
minimum of social disruptions. Shifting the canal towards Dhanushkody by another 3-4
km as recommended by the Steering Committee constituted by Ministry of Surface
Transport, Govt. of India for the present study would further minimise the impact due
to the land canal portion, and also be farther away from the National Marine Parks with
the advantage of reduced cost of dredging without significantly increasing the total
length of the canal. The alignment across the Dhanushkody island would not only
require cutting across the coral reefs but perhaps also blasting during construction.
From navigational considerations, this alignment with sharp turns is not considered
desirable. Thus, from all considerations including environmental and ecological, the
alignment recommended by the Steering Committee farther away from the
Kodandaramasamy temple towards Dhanushkody and with the crossing of the land
portion more or less at Moonru Iruppu Chatram appeared to be a better choice.
The present study recommended the use of navigational depth in Gulf of
Mannar by the ships to approach Adam’s Bridge from Tuticorin port. It could be
observed that ships can reach Adam’s Bridge area, enter the channel in South-North
direction parallel to medial line between Sri Lanka and India. The route thus would be
around 20-25 km away from the GOM biosphere reserves. As most stringent
regulatory practice for discharge of wastes from ship are recommended, the impacts
due to operation of this route an GOM biosphere reserves will be insignificant. The
dredged material will also be disposed 20-25 km away from GOM biosphere, the
movement of silt toward the biosphere is not envisaged. Thus the route would become
environmentally viable only if the management plans and recommended measures are
strictly followed.

Fig. 6.3 : Study Area for Route Alignment in Adam’s Bridge Area

\\\\
Fig. 6.4 : Borehole Data in Adam’s Bridge Area

12
10
y = 1E-07x2 - 0.0019x + 12.544
R2 = 0.6954
8
Depth (m)
6
4
2
0
0 5000 10000 15000 20000
Distance (m)
Fig. 6.5 : Bathymetry Along Line 1
y = material to be dredge
x = length
R2 = regretion wett

14
12
y = 9E-08x2 - 0.0018x + 12.842
R2 = 0.7058
10
Depth (m)
8
6
4
2
0
0 5000 10000 15000 20000
Distance (m)
Fig. 6.6 : Bathymetry Along Line 2

14
12
y = 1E-07x2 - 0.0021x + 14.129
R2 = 0.7281
10
Depth (m)
8
6
4
2
0
0 5000 10000 15000 20000
Distance (m)
Fig. 6.7 : Bathymetry Along Line 3

14
12
y = 7E-08x2 - 0.0017x + 13.886
R2 = 0.6426
10
Depth (m)
8
6
4
2
0
0 5000 10000 15000 20000
Distance (m)
Fig. 6.8 : Bathymetry Along Line 4

14
12
y = 6E-08x2 - 0.0017x + 14.224
R2 = 0.6709
10
Depth(meter)
8
6
4
2
0
0 5000 10000 15000 20000 25000
Distance(meter)
Fig. 6.9 : Bathymetry Along Line 5

q
38.33
39
37.56
Material to be dredged x 10 -6 m3
38
37
36.05 35.88
36
35
34
32.58
33
32
31
30
29
Line 1 Line 2 Line 3 Line 4 Line 5
Different Channels
Fig. 6.10 : Quantity Dredged Material along Various Tracks in
Adam’s Bridge

Fig. 6.13 : Cross Section of Proposed Channel

Fig. 6.14 : 3D Plume of Disposed Silt

Fig. 6.15 : Near Field

Fig. 6.16 : Far Field

Fig. 6.17 : Central Line Dilution

False Colour Composite
Fig. 6.18 : Geographical Domain Considered for Modelling

Longitude Latitude
Location
(Point)
79O21’03” 09O22’21”
1.
79O25’00” 09O16’15”
2.
79O00’00” 09O13’29”
3.
79O11’02” 09O15’38”
4.
79O13’10” 09O12’15”
5.
79O20’59” 09O11’50”
6.
79O13’10” 09O07’49”
7. 1
79O20’59” 09O08’25”
8.
79O13’10” 09O00’00”
9.
79O20’59” 09O00’00”
10.
2
Fig. 6.19 : Locations for Current Measurements

PAMBA Pt. 2
OCEAN SITE DATA COLLECTION DATE : 10/07/98
SACM No. : 014856 RDU NO : 017182 Speed (Knots) POSITION : LAT 09O22’21.46N LONG 79.O21’03.76”E
Speed (Knots)
Time (hrs.)
Fig. 6.20 : Tidal Stream Observations

PAMBA Pt. 2
OCEAN SITE DATA COLLECTION TIDAL STREAM OBSERVATIONS DATE : 11/07/98
SACM No. : 014856 RDU NO : 017182 Speed (Knots) POSITION : LAT 09O22’21.46N LONG 79.O21’03.76”E
Speed (Knots)
Time (hrs.)
Fig. 6.20 (Contd….)

Fig. 6.20 (Contd….)

Fig. 6.20 (Contd….)

Fig. 6.21 : Tidal Stream Observation

PAMBA Pt. 8
OCEAN SITE DATA COLLECTION TIDAL STREAM OBSERVATIONS DATE : 10/07/98
SACM No. : 016926 RDU NO : 016552 Direction (Degrees) POSITION : LAT 09O08’25N LONG 79.O20’59”E
Fig. 6.21 (Contd….)

PAMBA Pt. 8
OCEAN SITE DATA COLLECTION TIDAL STREAM OBSERVATIONS DATE : 11/07/98
SACM No. : 016926 RDU NO : 016552 Direction (Degrees) POSITION : LAT 09O08’25N LONG 79.O20’59”E
Fig. 6.21 (Contd….)

PAMBA Pt. 8
OCEAN SITE DATA COLLECTION TIDAL STREAM OBSERVATIONS DATE : 11/07/98
SACM No. : 016926 RDU NO : 016552 Direction (Degrees) POSITION : LAT 09O08’25N LONG 79.O20’59”E
Fig. 6.21 (Contd….)

Location : RAMESHWARAM (ND) R-J
Date : 10/07/98
Fig. 6.22 : Tidal Observations

Hydro-dynamic Modelling
Fig. 6.23 : Proposed Ship Navigation Alignment Considered for Modelling

Location : 20, 20
Water Heights (above Datum) in Mtrs.
Time (hrs)
Fig. 6.24 : Calibration Tide Heights

Location : 8
Fig. 6.25 : Calibration Currents

Fig. 6.26 : Spatial Current Predicted by the Model – Before Dredging

Fig. 6.27 : Spatial Current Predicted by the Model – After Dredging

Fig. 6.28 : Locations of Coral Reefs in the Modelling Domain (Adjoining Mandapam and Pambam Islands)

Fig. 6.29 : Locations of Coral Reefs in the Modelling Domain (Dhanushkodi Portion of Pambam Island)

Table 6.1
Bathymetry along Line: 1
S. No. Distance (km) Depth (m)
1 1 8.7
2 2 8.0
3 3 7.7
4 4 7.4
5 5 6.9
6 6 6.8
7 7 5.8
8 8 4.6
9 9 2.7
10 10 1.4
11 11 0.9
12 12 1.3
13 13 3.7
14 14 4.5
15 15 5.9
16 16 7.2
17 17 10.4
18 18 12.3

Table 6.2
Bathymetry along Line: 2
S. No. Distance (km) Depth (m)
1 1 9
2 2 8.6
3 3 8.3
4 4 8
5 5 7.5
6 6 6.9
7 7 6.1
8 8 4.8
9 9 3
10 10 2.2
11 11 4.1
12 12 1.5
13 13 3.3
14 14 3.6
15 15 5.2
16 16 7
17 17 6.3
18 18 12.2

Table 6.3
Bathymetry along Line: 3
S. No. Distance (km) Depth (m)
1 1 9.2
2 2 9.3
3 3 8.9
4 4 8.4
5 5 7.9
6 6 7.6
7 7 6.7
8 8 5.1
9 9 2.9
10 10 2.5
11 11 1.6
12 12 1.1
13 13 0.5
14 14 2.5
15 15 3.3
16 16 5.7
17 17 7.7
18 18 7.2
19 19 11.7
20 20 11.7

Table 6.4
Bathymetry along Line : 4
S. No. Distance (km) Depth (m)
1 1 9.5
2 2 9.3
3 3 9.5
4 4 9.1
5 5 7.59.1
6 6 9
7 7 8.3
8 8 7.3
9 9 5.6
10 10 2.8
11 11 2.4
12 12 1.1
13 13 0.8
14 14 1.1
15 15 2.7
16 16 3.4
17 17 6.1
18 18 6.7
19 19 8.3
20 20 8.3

Table 6.5
Bathymetry along Line : 5
S. No. Distance (km) Depth (m)
1 1 10.2
2 2 9.6
3 3 9.1
4 4 9.2
5 5 8.8
6 6 8.7
7 7 8.5
8 8 7.6
9 9 6
10 10 4.4
11 11 2.1
12 12 0.7
13 13 0.9
14 14 0.2
15 15 1.7
16 16 2.2
17 17 3.7
18 18 6.6
19 19 7.6
20 20 7

Table 6.6
Dredging Requirement for 10 m Depth (9.15 m draught)
and 300 m Width Channel
Quantity : million cu.m.
Section Bed Width Slope Tolerance Total Quantity
(See Fig. 6.12) Quantity Quantity Quantity
Adam’s Bridge
A-B 7.0 0.70 - 7.70
(CSD)
A-B 3.9 0.39 0.60 4.89 say 4.9
(TSHD)
B-C (TSHD) 9.6 0.96 1.3 11.86 say 11.9
Total 24.45 say 24.5
Palk Strait
E1-E2 2.4 0.24 1.79 4.43 say 4.45
E2-E3 8.2 0.82 1.29 10.31 say 10.35
Total 14.74 say 14.80

Table 6.7
Dredging Requirement for 12 m Depth (10.7 m draught)
and 300 m Width Channel
Quantity : million cu.m.
Section Bed Width Slope Tolerance Total Quantity
(See Fig. 6.12) Quantity Quantity Quantity
Adam’s Bridge
A-B 7.0 0.70 - 7.70
(CSD)
A-B 7.5 0.75 0.60 8.85 or say 8.9
(TSHD)
B-C 18 1.80 1.3 21.1
Total 37.7 or say 38
Palk Strait
E-E1 1.72 0.17 1.29 3.18 or say 3.2
E1-E2 14.25 1.43 1.79 17.47 or say 17.5
E2-E3 16.84 1.68 1.29 19.81 or say 19.8
E3-E4 2.43 0.24 0.49 3.16 or say 3.2
Total 43.7 or say 44
CSD : Cutter Suction Dredger
TSHD : Trailor Suction Hopper Dredger

Table 6.8
The Quantity of Dredged Material for 14 m Deep 500 Wide Channel
3
Quantity : million m
Section Bed Width Slope Tolerance Total Quantity
(See Fig. 6.12) Quantity Quantity Quantity
Adam’s Bridge
A-B 11.66 1.16 - 12.82
(CSD)
A-B 18.48 1.85 1.0 21.33
(TSHD)
B-C (TSHD) 44.00 4.40 2.17 50.57
Total 84.72 say 84.7
Palk Strait
C-D 33.25 3.32 5.70 42.27
D-E 39.00 3.90 6.00 48.90
E-E1 17.52 1.75 2.19 21.46
E1-E2 43.56 4.36 2.97 50.89
E2-E3 42.48 4.25 2.16 48.89
E3-E4 13.06 1.31 1.62 15.99
Total 228.4
Grand Total 313.1

Table 6.9
Expected Number of Transits through Sethusamudram Channel
Rs. in Crores
7m Draught 9m Draught 11 m Draught
Cargo
Transits Savings Transits Savings Transits (Per Savings
(Per year) (Rs.) (Per year) (Rs.) year) (Rs.)
POL & Specialized Cargo 282 39.39 366 51.97 522 75.75
Dry Bulk Cargo 120 11.92 120 11.92 120 11.92
General Cargo 1,306 16.82 1,306 16.82 1,362 19.81
Total 1,708 68.13 1,792 80.71 2,004 107.48

Table 6.10
Inputs to Model for Dredged Material Disposal
(12 m deep Channel)
Dredge Material Disposal in Gulf of Mannar Water
38x106m3
Volume of dredged material =
Composition of dredge = 95% sand and 5% silt
19,00,000 m3
Volume of Silt =
Total nos of day = 200 day
19,00,000/200 = 9500 m3/d
Per day silt disposal =
Silt disposed per sec = 9500 /(24*60*60) = 0.1099 m3/s
Assumed solution of silt = 10%
Volume of silt solution = 0.1099/0.1 = 1.099 m3/s
Density of solution = 0.1*1.2 +0.9*1.03 = 1.047 g/cc
Concentration of silt = 0.1*1200 = 120kg/m3
= 1,20,000 mg/l

Table 6.11
Maximum and Minimum Tidal Current (Speed) at Locations in
Palk Bay and Gulf of Mannar
Location Latitude Longitude Maximum Minimum
speed in knots speed in knots
Palk Bay
09o 22’ 21”.46 N 79o 21’ 03”.76 E
1 0.42 0.04
o o
2 09 16’ 15”.1 N 79 25’ 40”.0 E 0.62 0.03
Gulf of Mannar
09o 13’ 29”.0 N 79o 00’ 00”.0 E
3 0.31 0.02
o o
4 09 15’ 38”.0 N 79 11’ 02”.0 E 0.36 0.02
o o
8 09 08’ 25”.0 N 79 20’ 59”.1 E 0.29 0.06

Table 6.12
Speed and Direction of Currents for Patch-I
Before Dredging
Currents Patch-I
Speed in cms/sec
5 6 7 8 9 10 11 12 13 14 15
55 31.26 17.03 13.42 25.63 23.41 22.56 22.02 24.19 17.89 15.81 15.30
56 27.29 24.02 19.03 22.00 24.08 22.36 22.02 22.09 18.44 17.46 16.12
57 26.48 24.19 20.02 21.00 25.00 17.12 19.03 19.10 18.25 17.12 17.03
58 24.02 23.19 22.09 23.00 24.08 18.49 17.12 16.00 19.03 17.03 18.00
59 30.15 19.24 22.02 22.00 21.00 18.03 17.03 17.00 17.00 16.00 16.00
60 26.08 23.02 22.00 21.00 20.00 19.00 18.00 17.00 17.00 16.00 15.00
61 25.18 24.08 22.02 21.02 21.02 20.02 18.03 17.03 17.03 16.03 16.03
62 24.33 24.19 22.20 21.10 21.10 20.02 18.03 17.03 17.03 16.12 16.12
63 23.35 23.35 22.36 21.21 21.21 20.10 18.11 17.12 18.25 17.26 15.13
64 23.54 22.56 21.38 21.38 20.40 20.22 19.24 18.44 18.25 17.26 16.28
65 22.80 21.59 21.59 20.62 19.42 20.40 19.42 19.42 18.44 17.46 16.49
66 22.14 21.84 20.88 20.62 19.65 20.88 19.65 19.65 18.68 17.72 16.49
67 22.14 21.19 20.88 20.62 19.65 19.92 20.25 19.92 18.68 17.72 17.72
68 21.19 20.62 18.97 22.85 21.02 21.19 18.97 18.97 18.97 18.97 18.03
69 21.93 18.36 23.77 22.47 19.31 18.97 18.97 18.97 18.97 18.03 18.03
70 21.47 17.89 22.85 21.93 18.38 18.97 18.03 18.03 17.72 18.03 17.72
Direction in Degrees
5 6 7 8 9 10 11 12 13 14 15
55 277 183 297 291 290 283 273 187 207 198 191
56 278 272 183 270 275 280 273 185 193 193 187
57 281 277 273 270 270 187 183 186 189 187 183
58 182 277 275 270 185 194 187 270 273 273 270
59 276 189 183 270 270 183 183 270 270 270 270
60 274 272 270 270 270 270 270 270 270 270 270
61 277 275 273 273 273 273 273 273 273 274 274
62 279 277 278 275 275 273 273 273 273 277 277
63 280 280 280 278 278 276 276 277 279 280 278
64 282 283 281 281 281 279 279 283 279 280 281
65 285 283 283 284 282 281 282 282 283 283 284
66 288 286 287 284 285 287 285 285 286 286 284
67 288 289 287 284 285 288 290 288 286 286 286
68 289 293 288 293 295 289 288 288 288 288 289
69 294 299 292 291 288 288 288 288 288 289 289
70 298 297 293 294 292 288 289 289 286 289 286
Table 6.12 (Contd…)

After Dredging
Currents Patch-I
Speed in cms/sec
5 6 7 8 9 10 11 12 13 14 15
55 28.28 15 12.53 24.17 21.54 20.62 20.1 22.09 16.55 14.87 14.14
56 25.32 22.09 18.03 20.02 22.09 20.4 20.02 20.02 16.28 15.3 15.13
57 24.74 22.36 19.1 19.03 23.02 16.03 17.03 17.03 16.12 15.03 15
58 22 21.38 20.1 20.02 22.02 14.32 15.03 14 17.12 14.04 16
59 27.17 17.12 19.03 19 19 16 15 15.03 15.03 14 14
60 23.09 21.02 19.03 19.03 18.03 17.03 15.03 15.03 14.04 14.04 13.04
61 22.2 21.1 20.1 19.1 18.11 17.12 16.03 15.03 14.04 14.04 13.04
62 21.38 21.38 20.22 19.24 18.11 18.11 15.13 15.13 14.14 14.14 13.34
63 21.59 20.4 19.42 18.44 18.44 18.25 16.12 15.3 16.49 15.3 13.34
64 20.88 19.65 19.65 18.44 17.46 17.46 17.46 16.49 15.52 15.52 14.32
65 20.25 19.92 18.97 17.72 18.68 17.72 16.76 16.76 17.76 15.81 14.87
66 20.25 19.31 18.03 18.03 17.09 18.03 18.03 16.76 16.76 15.81 14.87
67 19.7 18.38 18.38 17.72 18.03 17.09 18.38 17.09 17.09 16.16 15.23
68 18.79 17.89 17.46 20.12 17.89 17.46 16.16 16.16 16.16 16.16 16.16
69 19.72 16.64 21.47 20.12 17.89 17.46 16.16 16.16 16.16 16.16 16.16
70 18.87 16.64 20.12 19.72 17 16.55 16.55 16.16 15.23 15.23 15.23
Direction in Degrees
5 6 7 8 9 10 11 12 13 14 15
55 278 270 299 294 292 284 276 185 205 200 188
56 279 275 183 273 275 281 273 183 191 191 188
57 284 280 276 273 272 184 183 183 187 184 270
58 270 281 276 273 183 192 184 270 277 274 270
59 276 187 183 270 270 270 270 274 274 270 270
60 275 273 273 273 273 273 274 274 274 274 274
61 278 275 276 276 276 277 274 274 274 274 279
62 281 281 279 279 276 276 278 278 278 278 283
63 283 281 282 283 283 279 277 281 284 281 283
64 287 285 285 283 283 283 283 284 285 285 282
65 290 288 288 286 286 286 286 287 287 285 286
66 290 291 289 289 291 289 289 287 287 288 290
67 294 292 292 286 289 291 292 291 291 292 293
68 295 297 294 297 298 295 291 291 291 292 293
69 300 303 298 297 297 294 292 292 292 292 292
70 302 303 297 300 298 295 295 292 293 293 293
Table 6.13

Speed and Direction of Currents for Patch-II
Before Dredging
Currents Patch-II
Speed in cms/sec
30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45
70 11 11 11 11 11 9.8 9.5 9.5 9.5 9.5 8.5 8.5 8.5 10 9.8 10
71 11 11 11 11 9.8 9.5 9.5 9.5 8.5 8.5 8.5 8.5 8.5 8.9 10 10
72 11 11 9.8 9.8 9.5 9.5 9.5 8.5 8.5 8.5 8.5 8.5 8.5 8.5 8.1 10
73 10 9.5 9.5 9.5 9.5 9.5 8.5 8.5 8.5 8.5 8.5 8.5 7.6 7.6 8.5 8.5
74 10 10 9.5 9.5 9.5 8.5 8.5 8.5 8.5 8.5 8.5 7.6 7.6 7.6 8.5 7.6
75 10 11 9.8 9.8 9.5 8.5 8.5 8.5 8.5 7.6 7.6 7.6 7.6 7.6 7.6 7.6
76 12 11 9.8 9.8 8.5 8.5 8.5 8.5 8.5 8.5 7.6 7.3 7.6 7.6 7.6 7.6
77 16 9.4 9.8 9.8 8.9 8.5 8.5 8.5 8.5 7.6 7.3 7.3 7.6 7.6 7.6 7.6
78 15 8.9 9.8 9.8 8.5 8.5 8.5 8.5 7.6 7.3 7.3 7.3 7.3 7.6 7.6 7.6
79 14 8.9 8.9 8.9 8.5 8.9 8.5 8.5 7.3 7.3 7.3 7.3 7.3 7.6 7.6 7.6
80 13 8.5 8.5 8.9 9.8 8.5 8.5 7.6 7.6 7.3 7.3 7.3 7.3 7.3 7.3 7.6
Direction in Degrees
30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45
70 292 292 292 292 292 294 288 288 288 288 291 291 291 299 294 299
71 292 292 292 292 294 288 288 288 288 291 291 291 291 297 299 299
72 292 292 294 294 288 288 288 291 291 291 291 291 291 291 300 299
73 287 288 288 288 288 288 291 291 291 291 291 291 293 293 291 291
74 287 287 288 288 288 291 291 291 291 291 291 293 293 293 291 293
75 287 292 294 294 288 291 291 291 291 291 293 293 293 293 293 293
76 290 297 294 294 291 291 291 291 291 291 293 286 293 293 293 293
77 297 302 294 294 297 291 291 291 291 293 286 286 293 293 293 293
78 293 297 294 294 291 291 291 291 293 286 286 286 286 293 283 293
79 295 297 297 297 291 297 291 291 286 286 286 286 286 293 293 293
80 297 291 291 297 294 291 291 293 293 286 286 286 286 286 286 293

Table 6.13(Contd…)
After Dredging
Currents Patch-II
Speed in cms/sec
30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45
70 8.94 8.06 8.06 8.06 8.06 7.21 7.21 7.21 7.21 7.21 6.40 6.40 6.40 7.81 5.66 5.83
71 8.06 8.06 8.06 8.06 8.06 7.21 7.21 7.21 7.21 6.40 6.40 6.40 6.40 5.66 6.40 8.60
72 8.06 8.06 8.06 8.06 7.21 7.21 7.21 7.21 7.21 6.40 6.40 6.40 6.40 5.66 6.40 7.81
73 8.06 8.06 8.06 7.21 7.21 7.21 7.21 7.21 7.21 5.83 5.83 6.40 6.40 5.66 7.07 7.07
74 8.06 8.06 8.06 7.21 7.21 7.21 7.21 7.21 5.83 5.83 6.40 6.40 6.40 6.40 6.40 7.07
75 8.94 8.06 8.06 7.21 7.21 7.21 7.21 5.83 5.83 6.40 6.40 6.40 6.40 6.40 6.40 6.40
76 9.85 8.60 8.60 7.21 7.21 7.21 7.21 6.40 6.40 5.83 5.83 5.83 5.83 6.40 6.40 6.40
77 13.04 7.81 7.21 7.21 7.21 7.21 7.21 6.40 5.83 5.83 5.83 5.83 5.83 6.40 6.40 6.40
78 12.21 7.81 7.21 7.21 7.21 7.21 7.21 6.40 6.40 5.83 5.83 5.83 5.83 6.40 6.40 6.40
79 11.40 7.21 7.21 7.81 7.21 7.21 7.21 6.40 5.83 5.83 5.83 5.83 5.83 6.40 6.40 6.40
80 7.21 7.21 7.81 7.81 7.81 7.21 7.21 6.40 6.40 5.83 5.83 5.83 5.83 5.83 6.40 6.40
Direction in Degrees
30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45
70 297 300 300 300 300 304 304 304 304 304 309 309 310 315 315 329
71 300 300 300 300 300 304 304 304 304 309 309 309 315 321 321 324
72 300 300 300 300 304 304 304 304 304 309 309 309 315 321 321 320
73 300 300 300 304 304 304 304 304 304 301 301 309 315 315 315 315
74 300 300 300 304 304 304 304 304 301 301 309 309 309 309 309 315
75 297 300 300 304 304 304 304 301 301 309 309 309 309 309 309 309
76 294 306 306 304 304 304 304 309 309 301 301 309 309 309 309 309
77 302 310 304 304 304 304 304 309 301 301 301 309 309 309 309 309
78 305 310 304 304 304 304 304 309 309 301 301 301 309 309 309 309
79 308 304 304 310 304 304 304 309 301 301 301 301 309 309 309 309
80 304 304 310 310 310 304 304 309 309 301 301 301 301 309 309 309

Table 6.14
Speed and Direction of Currents for Patch-III
Before Dredging
Currents Patch-III
Speed in cms/sec
51 52 53 54 55 56 57 58 59 60 61 62 63 64 65
70 13.42 11.66 12.53 13.42 11.66 9.22 10.82 8.00 0.00 0.00 0.00 0.00 0.00 0.00 3.00
71 12.53 11.18 11.18 11.18 11.18 12.53 12.08 10.00 10.82 7.00 0.00 0.00 0.00 0.00 0.00
72 9.85 9.85 9.85 9.85 9.85 10.77 11.18 11.66 9.22 8.54 7.00 0.00 0.00 0.00 0.00
73 9.85 8.54 8.54 8.54 8.94 10.30 11.18 12.53 13.42 14.32 13.00 8.49 10.63 7.00 0.00
74 8.94 8.54 7.62 7.62 8.06 8.94 10.30 11.18 11.18 11.18 10.30 10.82 8.49 77.31 10.00
75 8.06 7.62 6.71 6.71 6.71 7.21 8.06 9.43 9.43 9.43 10.00 10.00 9.90 15.81 15.00
76 8.06 8.06 7.21 6.71 6.71 7.21 7.21 7.21 7.81 9.22 9.22 9.22 10.82 10.00 10.00
77 8.06 7.21 7.21 7.21 6.40 6.40 6.40 6.40 7.07 7.81 7.81 9.22 9.90 8.49 8.49
78 8.06 7.21 7.21 7.21 6.40 6.40 5.66 5.66 5.66 5.66 5.66 8.49 8.60 7.81 7.81
79 8.06 7.21 7.21 7.21 6.40 6.40 5.66 5.66 5.66 5.66 5.66 6.40 7.21 8.06 8.06
80 6.71 8.06 7.21 7.81 7.07 7.07 6.40 6.40 6.40 5.66 5.83 5.83 7.21 8.06 8.06
81 8.06 8.06 7.21 7.81 7.81 7.07 7.07 6.40 6.40 6.40 5.83 5.83 6.71 7.62 7.62
82 8.06 8.06 8.60 7.81 7.81 7.81 7.07 7.07 6.40 6.40 6.71 6.71 6.71 7.62 7.62
Direction in Degrees
51 52 53 54 55 56 57 58 59 60 61 62 63 64 65
70 297 301 299 297 301 311 326 0 0 0 0 0 0 0 270
71 299 297 297 297 297 299 294 307 326 0 0 0 0 0 0
72 294 294 294 294 294 292 297 301 311 339 0 0 0 0 0
73 294 291 291 291 297 299 297 299 297 295 293 315 319 0 0
74 297 291 293 293 300 297 299 297 297 297 299 304 315 315 0
75 300 293 297 297 297 304 300 302 302 302 307 307 315 305 307
76 300 300 304 297 297 304 304 304 310 311 311 311 304 307 307
77 300 304 304 304 309 309 309 309 315 310 310 311 315 315 315
78 300 304 304 304 309 309 315 315 315 315 315 315 324 320 320
79 300 304 304 304 309 309 315 315 315 315 315 321 326 330 330
80 297 300 304 310 315 315 321 321 321 315 329 329 326 330 330
81 300 300 310 310 310 315 315 321 321 321 329 329 333 337 337
82 300 300 306 310 310 310 315 315 321 321 333 333 333 337 337

Table 6.14 (Contd…)
After Dredging
Currents Patch-III
Speed in cms/sec
51 52 53 54 55 56 57 58 59 60 61 62 63 64 65
14.14 13.45 14.21 15.81 12.21 9.90 10.82 9.00 0.00 0.00 0.00 0.00 0.00 0.00 5.00
70
12.73 12.04 12.21 12.21 12.21 13.04 12.53 10.00 10.30 7.00 0.00 0.00 0.00 0.00 0.00
71
10.00 10.00 10.82 10.30 10.30 10.30 10.82 1.82 9.90 7.28 6.00 0.00 0.00 0.00 0.00
72
10.00 8.60 8.60 9.43 9.43 10.30 11.66 11.66 12.53 14.32 12.08 8.49 10.00 7.00 0.00
73
8.60 7.81 7.81 7.21 8.60 8.60 10.00 10.82 10.82 10.82 10.00 10.82 8.49 11.31 9.00
74
7.81 7.81 7.81 7.07 7.81 7.81 8.60 9.22 10.00 10.00 10.00 10.63 9.90 15.00 14.21
75
7.81 7.81 7.07 7.07 7.07 7.07 7.07 7.81 7.07 9.22 9.90 9.90 10.63 10.00 10.00
76
7.81 7.07 7.07 7.07 7.07 6.40 6.40 6.40 7.07 7.07 7.81 9.22 9.90 8.49 8.49
77
7.07 7.07 7.07 7.07 6.40 6.40 6.40 6.40 6.40 5.66 6.40 8.60 8.60 8.60 7.21
78
7.07 7.07 7.07 7.07 6.40 6.40 6.40 6.40 5.83 5.83 5.83 5.83 7.21 8.06 7.62
79
6.40 7.07 7.07 7.81 7.21 6.40 6.40 5.83 5.83 5.83 5.83 5.39 7.62 8.06 8.54
80
7.07 7.07 7.81 7.81 7.81 7.21 7.21 7.21 6.71 5.83 6.71 6.32 7.62 7.62 8.54
81
7.07 7.07 7.07 7.81 7.81 7.81 7.21 7.21 7.21 6.71 6.71 7.62 7.62 7.62 8.25
82
Direction in Degrees
51 52 53 54 55 56 57 58 59 60 61 62 63 64 65
315 312 309 305 305 315 326 0 0 0 0 0 0 0 270
70
315 312 305 305 305 302 299 307 331 0 0 0 0 0 0
71
307 307 304 299 299 299 304 304 315 344 0 0 0 0 0
72
307 306 306 302 302 299 301 301 299 295 294 315 323 0 0
73
306 310 310 304 306 306 307 304 304 304 307 304 315 315 0
74
310 310 310 315 310 310 306 311 307 307 307 311 315 307 309
75
310 310 315 315 315 315 315 310 315 311 315 315 311 307 307
76
310 315 315 315 315 321 321 321 315 315 320 319 315 315 315
77
315 315 315 315 321 321 321 321 321 315 321 324 324 324 326
78
315 315 315 315 321 321 321 321 329 329 329 329 326 330 337
79
309 315 315 320 326 321 321 329 329 329 329 338 337 330 339
80
315 315 320 320 320 326 326 326 333 329 333 342 337 337 339
81
315 315 315 320 320 320 326 326 326 333 333 337 337 337 346
82

Table 6.15
Speed and Direction of Currents for Patch-IV
Before Dredging
Currents Patch-IV
Speed in cms/sec
51 52 53 54 55 56 57 58 59 60 61 62 63 64 65
45 23.35 13.60 6.08 0.00 0.00 0.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00
46 13.34 13.00 8.06 7.07 3.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00
47 13.00 9.85 5.39 1.41 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00
48 13.93 9.49 4.12 1.41 2.00 1.00 2.00 2.00 2.00 2.00 2.00 2.00 1.00 1.00 1.00
49 13.00 10.20 7.07 3.00 9.06 2.00 2.00 3.00 11.40 19.24 18.25 19.24 16.12 16.12 12.17
50 13.93 13.34 13.04 11.00 25.02 28.07 27.17 15.30 10.44 19.24 19.24 22.20 11.40 12.17 12.17
51 15.23 18.11 23.00 32.02 30.07 29.15 28.16 18.25 14.32 18.25 19.10 24.08 11.40 12.37 12.17
52 18.03 21.10 24.08 27.17 27.17 26.17 24.19 21.10 19.24 20.22 21.10 24.08 13.15 12.37 12.17
53 21.19 22.80 24.33 25.71 26.31 25.32 21.21 20.22 21.10 22.09 22.09 23.09 16.12 11.18 13.15
54 23.41 24.35 24.19 25.71 26.48 26.31 12.65 13.60 28.28 22.09 22.09 21.10 19.10 12.17 14.14
55 25.63 25.30 25.08 27.46 31.26 17.46 13.00 24.52 22.56 22.36 22.20 24.08 16.12 15.13 15.13
Direction in Degrees
51 52 53 54 55 56 57 58 59 60 61 62 63 64 65
45 350 343 351 0 0 0 90 90 90 90 90 90 90 90 90
46 347 337 353 352 0 90 90 90 90 90 90 90 90 90 90
47 337 336 338 315 0 90 90 90 90 90 90 90 90 90 90
48 339 342 346 225 180 90 90 90 90 90 90 90 90 90 90
49 337 349 352 0 84 90 90 90 90 90 90 90 90 90 90
50 339 347 356 0 88 86 84 79 73 81 81 82 75 81 81
51 337 354 0 88 86 84 84 81 78 81 84 83 75 76 81
52 341 355 85 84 84 83 83 85 81 82 85 85 81 76 81
53 341 345 81 77 81 81 82 82 85 85 85 85 83 80 81
54 340 341 83 77 79 81 72 73 82 85 85 85 84 81 82
55 339 342 85 80 83 77 67 78 77 80 82 85 83 82 82

Table 6.15 (Contd…)
After Dredging
Currents Patch-IV
Speed in cms/sec
51 52 53 54 55 56 57 58 59 60 61 62 63 64 65
45 4.47 4.00 3.16 0.00 1.00 1.00 1.41 1.41 2.24 2.24 2.24 3.16 4.12 4.12 5.10
46 3.16 5.10 2.24 1.41 0.00 1.00 1.41 1.41 2.24 2.24 3.16 3.16 4.12 4.12 5.10
47 5.39 4.12 2.83 2.24 1.00 1.41 1.00 1.41 2.24 2.24 3.16 3.16 3.16 5.10 5.10
48 5.39 3.16 1.41 3.16 3.00 2.24 2.00 2.24 2.83 2.83 3.61 3.16 4.12 5.10 5.10
49 5.39 2.00 1.41 5.00 4.12 3.61 2.24 3.16 3.61 3.61 4.24 4.47 4.47 5.39 6.32
50 6.40 3.61 1.00 6.00 5.10 4.47 3.61 3.00 3.16 3.16 4.24 5.00 5.83 6.32 7.28
51 7.81 3.61 1.00 8.06 6.32 5.00 3.61 3.00 3.61 3.61 3.61 5.00 5.83 6.71 7.28
52 8.49 5.39 4.47 9.49 7.62 5.00 3.61 2.00 4.24 4.24 4.47 5.39 6.32 7.62 8.25
53 8.60 10.00 10.77 10.82 8.06 6.40 4.24 3.00 3.61 3.61 4.47 5.39 5.39 6.32 8.25
54 12.04 16.12 15.30 10.82 7.81 5.66 5.00 4.00 4.47 4.47 5.39 5.39 5.39 6.32 8.25
55 13.45 17.00 20.10 10.30 7.21 5.66 5.83 5.00 5.66 5.66 5.83 5.39 5.39 5.39 8.25
Direction in Degrees
51 52 53 54 55 56 57 58 59 60 61 62 63 64 65
45 297 270 252 0 180 180 135 135 153 153 153 162 166 166 169
46 288 191 243 315 0 90 135 135 153 153 162 162 166 166 169
47 292 194 225 333 0 45 90 135 153 153 162 162 162 169 169
48 292 198 225 342 0 63 90 117 117 135 146 162 166 169 169
49 292 270 225 0 76 56 27 108 108 124 135 153 153 158 162
50 309 304 270 0 79 63 34 90 108 108 135 143 149 162 164
51 310 326 0 83 72 53 34 90 124 124 146 143 149 153 164
52 315 338 63 72 67 53 34 90 124 135 153 158 162 157 166
53 306 323 68 56 60 51 45 90 135 146 153 158 158 162 166
54 318 330 79 56 50 45 37 90 117 153 158 158 158 162 166
339 318 332 84 61 56 45 31 90 112 135 149 158 158 158 166

7. Environmental Management Plan
7.1 Construction Phase
7.1.1 Acquisition of Land for Onshore Facilities
Requirement of land in coastal areas of Ramnathpuram and Rameshwaram
towns has been envisaged by Tuticorin Port Trust for construction of administrative
buildings, residential quarters, facilities for mobilizing and monitoring of construction
activities in Adams Bridge area. The majority of land in Pamban island belongs to
Govt.; however the fishermen inhabit the coasts in Dhanushkody and Arimunai area.
Though land requirement has been minimized due to shifting of canal alignment,
displacement of fisherman in Dhanushkody and Arimunai is envisaged during
construction phase. A proper rehabilitation plan will be drawn for fishermen during
construction phase and maximum land will be returned to users after the construction
activities are completed.
7.1.2 Dredging Activity
Major phase of construction will involve dredging in Adam’s Bridge area
resulting into generation of 38 million cu. m. of dredged spoil. From the shallow
seismic data, it is observed that 0.5 to 1 m sea bottom comprise clay and silt followed
by hard and soft sand upto a depth of 12.0 m below CD. It is proposed to use 7 to 8
million m3 of dredged spoil for nourishment of coastal area for its consolidation using
clay, silt and sand present in excavated material. The degraded areas of Pamban
island are proposed to be reclaimed using a portion of dredged spoil. The land thus
reclaimed will be developed for vegetation and partially for habitation. Tuticorin Port
Trust (TPT) in consultation with state authorities will identify area which can be
acquired for development. These areas after development will be used for habitation
and greenbelt plantation. A provision for budget to resettle the fishermen as well
vegetation will be made by TPT.
Balance dredged spoil, about 30 million cu.m. will be transported for disposal
to sea at a location having depths ranging from 30 to 40 m and atleast 20 km away
from Gulf of Mannar marine national park. Adequate distance from international medial

line will also be maintained. This is to prevent impacts on ecologically sensitive coastal
areas in GOM and to minimize transboundary effects. About 44 million m3 of dredged
material generation is envisaged during dredging in Palk Bay and Palk Strait area
Dredge material will not be disposed in Palk Bay. It is proposed to dispose this
material in Bay of Bengal at suitable depth (more than 25 m bathymetry) in open sea
so as to avoid any impacts on coastal areas particularly in the vicinity of Point
Calimere. This would involve high lead distances (between 30 & 60 km) for disposal
vessel requiring higher investments on costs. During excavation and transportation of
dredged spoil, fishing communities will be informed about the schedule so as to
minimize impacts on fishing activities. During transportation of dredged spoil,
precautionary measures will be taken to avert collision of ships with fishing boats,
damage to fishing nets and also to marine animals crossing the path of the
vessel/barges.
During dredging activities, the equipments, vessels, barges required for
dredging and transportation of dredged spoil will be maintained in secured area and
spillage of oil or any toxic material including paints, anticorrosive agents etc. will not be
allowed to spill in sea/coastal waters. Movement of barges for transporting dredged
spoil to land area will not interfere with movement of fishing boats in both Gulf of
Mannar and Palk Bay region adjoining the Adam’s Bridge.
During dredging and disposal activities monitoring of marine environmental
quality be periodically done to assess the impact of dredging and disposal on water
quality with respect to suspended solids load.
It is also recommended that existing jetties at Rameshwaram which only cater
to fishing activities presently should be augmented to cater to the requirement of
handling dredging activities in Adam Bridge and Palk Bay area. This would provide
fisherman with better facilities to operate during adverse tidal conditions.
Transportation of construction material in the vicinity of Adam’s Bridge will be by sea
route using the available navigational depths of heavy machinery.
Transportation
During transportation of heavy equipments and machinery by road, care will
be taken to avoid traffic hazard, traffic congestion and if required roads will be
augmented to meet the conditions of hazard free transportation.

7.2 Operational Phase
7.2.1 Route Alignment
The proposed navigation route in Gulf of Mannar will be about 20 km from all
the 21 islands except Van Tiu which is about 9 km from Tuticorin Harbour. These
islands falling in marine national park are ecologically sensitive due to presence of
diverse flora and fauna. With a view to minimize impacts of developmental activity on
this marine national park, the canal alignment in Gulf of Mannar is suggested in such a
way that only navigational depths will be used hence no dredging activity will be
required. The alignment in this region will be at depths greater than 20 m and would
keep a distance of about 20 km from marine national park. The ships originating from
TPT will however be about 9 km away from Van Tiu and later take a designated
navigation route once out of Tuticorin harbour area. Ship traffic bypassing Tuticorin
Port will maintain a distance of more than 20 km from biosphere reserves throughout
the transit in Gulf of Mannar and Adam’s Bridge. In Adam’s Bridge area the 300 m
wide channel will be along line no. 2 for which bathymetry was studied (pl. refer Fig.
2.48)
7.2.2 Discharges from Ships
All the ships originating from Tuticorin Port will comply to Marpol Conventional
1973/78 and CPCB regulations for discharge of bilge, ballast, effluents etc. into sea.
However keeping in view the sensitivity of the region, ships will not be allowed to
discharge any effluents viz. bilge, ballast, treated sewage, deck washings, oily wastes,
spillages etc. into sea so that water quality and living organisms are not affected. The
traffic of ships carrying crude oil will be handled with strict vigilance so as to avoid
possibility of spillage. Tuticorin port has been handling oil ships for last 25 years and
not a single incidence of oil spill has been reported. The oil spill contingency plan in
operation at TPT will be extended to navigation in new channel. It is suggested that a
pilot should board the vessel from Tuticorin to navigate ship through GOM area up to
Bengal Channel in Palk Bay. This will help in keeping vigil on discharges from ship as
well as ship movement so that it would not drift towards marine park area.
Traditional fishing using mechanised and non mechanised boats will not get
affected as width of canal will be 300 m and rest of the sea is available for fishing. The
channel will be properly marked by navigational light buoys. Accidents by collision of

ships with fishing boats will be totally prevented by slowing down the cruise speed
and also alerting the fisherman by cautionary measures. During implementation and
operational phases of the project, TPT will take action to avoid the collisions of ships
with fishing boats or damage to fishing nets with cooperation from fishing
communities, Navy, Coast Guards and other Govt. authorities. Suitable timings apart
from ship transit will be given for fishermen to continue with their fishing activities. With
the deepening of channel in Adam’s Bridge area it would be possible for fishermen to
access fishing area in Gulf of Mannar from Palk Bay and Vice-Versa. No special
permission would be required by fishermen to use the transit. It is recommended that
TPT will provide a corridor both in terms of space and time to fishermen living in
coastal areas of Rameshwaram, Mandapam and Ramnathpuram to access the canal
for moving across the ridge from Palk bay to Gulf of Mannar and Vice-versa.
Tuticorin Port Trust, keeping in view the sensitive coastal ecology, would
ensure that there will not be any open sea accidents and ships will follow a defined
sea waterway and the national and international regulations on safe navigation to
avoid any oil spill. The defaulters will be punished with fines and imprisonment. An
environmental watcher will board every ship that will transit the canal along with the
pilot at Tuticorin to caution the ships about movement of fishes and marine animals,
particularly movement of mammals, dolphins, sea cow, turtles etc. to prevent any
damage to this biological wealth of Gulf of Mannar. Movement of fishing boats,
placement of fishing nets will be watched by both pilot who also will be responsible on
behalf of TPT to prevent any discharges from ships. The traffic management along the
canal will be controlled by TPT. The port currently handles 1600 ships per annum at
TPT. The traffic projected with 9.15 m draft will be 1792 whereas for 10.7 m draft it will
be slightly more. Hence there will be marginal increase in traffic. Management facilities
at TPT will be augmented to handle the increased traffic.
TPT will ensure following from the ships transiting the canal :
• Ships should not use paints, anti corrosive agents of toxic nature on ship
bottoms
• All the ships berthing at TPT will have sewage treatment facilities however no
ship will be allowed to discharge treated sewage in Gulf of Mannar area

• Ships bypassing TPT and transiting the canal will also be inspected for its
navigational safety measures before it is allowed to enter the canal
alignment.
7.2.3 Maintenance Dredging
Maintenance dredging of about 0.1 million m3 per year is envisaged in the
Adam’s Bridge area and about 0.45 million m3 in Palk Bay area totalling to 0.55 million
m3 for centre channel based on data available for sediment transport across Palk Bay
and Gulf of Mannar. The dredged material will be mostly silt and clay and will not be
disposed in sea. Instead it will be used to reclaim degraded areas on Pamban island,
Ramnad and Mandapam coastal stretches. The studies carried out by NSDRC
signifies that the region around Adam’s Bridge forms an significant sink for the littoral
drift. The prolonged accumulation in the area may lead to the emergence of new
islands. In case of occurrence of cyclones in Gulf of Mannar, such prolonged
deposition of sediments move north and enter Palk Bay through Pamban Pass and
Adam’s Bridge. Once the sediment enter the Palk Bay, the environmental conditions
favours immediate deposition. Hence the occurrence of cyclones in Gulf of Mannar
and the associated northerly waves might exchange more sediment from the southern
part of Peninsular India to Northern parts of east coast. Thus the quantity of
maintenance dredged spoil will increase in the channel across Adam’s Bridge in the
event of cyclones.
To cater to increase in trade envisaged due to this project and to transfer
benefit to local fisherman, a minor port facility can be created at Rameshwaram in
consultation with state authorities.
An oil spill contingency plan will be drawn by Tuticorin Port Trust with
preparedness to prevent spread of oil or any cargo spillage in Gulf of Mannar and Palk
Bay and its immediate recovery by deploying equipments and ships.
7.3 Summary of Environmental Management Plan
7.3.1 Construction Phase
• No dredging will be done in Gulf of Mannar except in Adam’s Bridge
area

• Alignment of navigation route in Gulf of Mannar will be minimum 20
km away from marine national park
• Land acquired for mobilization and monitoring of activity will be
returned to users after completion of dredging activity
• A proper rehabilitation plan for the fisherman at Dhanushkody will be
drawn during construction phase
• Dredged spoil comprising clay and sand upto 2 m of dredging depth
will be used for reclaiming degraded land in Pamban island, subject to
approval to under CRZ regulation. Balance dredged spoil will be
disposed in sea at a depth 30-40 m, 20-25 km away from Gulf of
Mannar islands. Dredged spoil generated in Palk Strait / Palk Bay area
will be disposed in open sea in Bay of Bengal at depth more than 25-40
m, 30-60 km away from dredging area
• Safe distance from international medial line will be maintained
• During dredging activities, the equipments, vessels, barges required for
dredging and transportation of dredged spoil will be maintained in
secured area and spillage of oil or any toxic material including paints,
anticorrosive agents etc. will not be allowed to spill in sea/coastal
waters
Movement of barges for transporting dredged spoil to land area will not interfere
with movement of fishing boats in both Gulf of Mannar and Palk Bay region
adjoining the Adam’s Bridge
• It is also recommended that existing jetties at Rameshwaram which
only cater to fishing activities presently should be augmented to cater
to the requirement of handling dredging activities in Adam Bridge and
Palk Bay area
• Transportation of heavy machinery and construction material in the
vicinity of Adam's Bridge will be by sea route using the available
navigational depths

• During transportation of heavy equipments and machinery by road,
care will be taken to avoid traffic hazard, traffic congestion and if
required roads will be augmented to meet the conditions of hazard free
transportation.
7.3.2 Operational Phase
• All the ships originating from Tutitcorin Port will comply to International
Maritime Standards and follow MARPOL convention (MARPOL 73/78)
• Discharge of bilge, ballast, treated sewage, solid wastes, oily wastes
and spillage of cargo will not be allowed in the Gulf of Mannar area
• The traffic of crude oil tankers will be allowed in this route with strict
vigilance so as to avoid any possibilities of spillage in this region
• It will be ensured that ships navigating in this region should not use
such paints and anticorrosive agents on ship bottom which can cause
damage to marine organisms
• A pilot should be trained or environmental watcher will board the ship
to watch marine animals viz. turtle, dolphins, sea cow etc. in the region
and navigate the ship safely avoiding any damage to this fauna.
• It will be ensured that all the ships berthing at TPT as well as all those
using the route without touching TPT will have proper treatment
facilities for sewage however discharge of treated sewage will not be
permitted in GOM area
• Ships bypassing TPT and transiting the channel will be inspected for its
navigational safety measures before it is allowed to enter proposed
navigation route
• An oil spill contingency plan will be drawn by Tuticorin Port Trust with
preparedness to prevent spread of spillage in Gulf of Mannar and Palk
Bay area and its immediate recovery by deploying equipments and
ships
• To benefit large fishing communities in the coastal area of
Ramnathpuram and Rameshwaram, a corridor both in terms of space

and time be provided to fisherman to use the channel in Adam’s Bridge
area for moving across Palk Bay to GOM and vice versa for fishing
activity
• The jetties at Rameshwaram are in dilapidated conditions. A
programme to construct a few Jetties at Pamban island to augment
fishing activity in the region be supported by TPT
• The traffic of ships carrying crude oil will be handled with strict vigilance
so as to avoid possibility of spillage
• The oil spill contingency plan in operation at TPT will be extended to
navigation activities in new channel
• A pilot will board the vessel from either from Rameshwaram or
appropriate place to navigate ship through GOM area up to Bengal
Channel in Palk Bay
• The channel will be properly marked by navigational light buoys
• Accidents by collision of ships with fishing boats will be totally
prevented by slowing down the cruise speed and also alerting the
fisherman by cautionary measures. During implementation and
operational phases of the project, TPT will take action to avoid the
collisions of ships with fishing boats or damage to fishing nets with
cooperation from fishing communities, Navy, Coast Guards and other
Govt. authorities
• Suitable timings apart from ship transit will be given for fishermen to
continue with their fishing activities
• A corridor both in terms of space and time will be provided to fishermen
living in coastal areas of Rameshwaram, Mandapam and
Ramnathpuram to access the channel for moving across the ridge from
Palk bay to Gulf of Mannar and Vice-versa
• Maintenance dredging of about 0.55 million m3 per year is envisaged in
the channel based on data available for sediment transport across Palk
Bay and Gulf of Mannar

• To cater to increase in trade envisaged due to this project and to
transfer benefit to local fisherman, a minor port facility can be created
at Rameshwaram in consultation with state authorities.
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Environmental Impact Assessment for Proposed
Sethusamudram Ship Channel Project
Executive Summary
1.0 Introduction
India does not have, within her own territorial waters, a continuous navigable
route around the peninsula due to the presence of a shallow (1.5 to 3.5 m depth) ridge
called ‘Adam’s Bridge’ between Pamban island on south-eastern coast of India and
Talaimannar of Sri Lanka. While Rameshwaram is a major pilgrim centre on Pamban
island, the tip of the island is marked by Arimunai. Consequently, the ships calling at
ports on the east coast of India have to go around Sri Lanka entailing an additional
distance of about 254-424 nautical miles and about 21-36 hours of ship time.
The Sethusamudram Ship Channel Project under the consideration of the
Ministry of Shipping, Government of India, envisages creation of a ship navigation
channel to suit different draughts (9.15 m, 10.7 m and 12.8m) through
dredging/excavation in Adam’s Bridge, parts of Palk Bay and Palk Strait. The
navigation route will originate from the Tuticorin new harbour in the Gulf of Mannar
(GOM) using available navigation depths (> 20 m) up to south east of Pamban Island,
pass through a channel created in Adams Bridge within the International boundary and
proceed parallel to the International Medial Line for fishing rights as the Bengal
Channel. In Palk Bay area availability of depths in middle channel, capital dredging
across Adams Bridge and in Palk Strait and continuous maintenance dredging along
the proposed transit are the critical project related issues.
The routes selected through earlier studies particularly in Gulf of Mannar area
have been rejected, keeping in view sensitivity along the coastal stretch of GOM
harbouring marine national park. Instead a navigation route keeping a minimum 6-8
km distance from Van Tiu near Tuticorin and more than 20 km from Shingle in Adams
Bridge approach area has been suggested.

Tuticorin Port Trust (TPT), the nodal agency identified by Ministry of Shipping,
Govt. of India for the implementation of the project in pursuance of its decision to
incorporate environmental considerations in the design phase of the project, retained,
in March 2002, National Environmental Engineering Research Institute (NEERI) to
conduct the Environmental Impact Assessment (EIA) study for the project.
This report presents briefly the project setting, describes the baseline
environmental status of the project area, identifies environmental issues, predicts and
evaluates impacts due to the proposed project and delineates environmental
management plan to mitigate potential adverse impacts.
The EIA study has primarily drawn upon the available information on the
proposed project, the hydrography, marine water quality and ecological resources in
the project area, and the primary data generated during the course of study. This
environmental impact assessment study with intensive data collection has resulted
into fuller description and appreciation of the natural processes occurring in the study
area, and delineates the environmental consequences including the ecological risk
associated with the proposed project with or without proper environmental
management plan.
2.0 Project
The proposed Sethusamudram ship channel will have two legs, one near the
Point Calimere called the Bay of Bengal Channel and the other across the Adams
Bridge. The Bay of Bengal Channel traverses the Palk Bay wherein the sea-bed is
mostly soft to hard clayey-sand in nature. Some hard strata has been reported beneth
the soft sand during recent survey by the National Hydrographic Office, Dehradun.
The area adjoining Adma’s Bridge, Dhanushkody Peninsula on the North and the
South is reported to be sandy by National Ship Design Research Centre (NSDRC),
Visakhapatnam during their survey in connection with this project.
While navigational depths will be used in Gulf of Mannar from Tuticorin Port to
Adam’s Bridge area, a 20 km long, 300 m wide channel with 10.7 m draught with two
way controlled traffic is proposed to be created as ultimate phase by dredging shallow
area of Adam’s Bridge upto 12 m depth. Similar excavation will be done in Palk Strait
and adjoining parts of Palk Bay to achieve the required depth over a stretch of around
36 km and 18 km respectively. A control station, administrative building and Vessel

Traffic Management System (VTMS) is proposed to be located at Rameshwaram
island between Dhanushkodi and Koil Nagar village to control navigation, besides
other infrastructure including administrative requirements.
3.0 Environmental Regulations
At the National level, the environmental clearance to the project is subject to
compliance with the stipulated safeguards under the provisions of Environment
(Protection) Act, 1986; Forest (Conservation) Act, 1980; The Water (Prevention and
Control of Pollution) Act, 1974; The Water (Prevention and Control of Pollution) Rules,
1975; The Water (Prevention and Control Pollution) Cess Act, 1977. The Water
(Prevention and Control of Pollution) Act, 1981; and other rules and regulations in
force. Land use on the coastline will be subject to regulation as per the Coastal
Regulation Zone (CRZ) Notification issued by the Ministry of Environment and Forests
(MoEF), Government of India in 1991 and subsequent amendments under the
Environmental Protection Act. This notification is administered by the State
Department of Environment and Forests.
The Wildlife (Protection) Act of India (1972) provides legal protection to many
marine animals including reef associated organisms. Chapter IV of this Act dealing
with Sanctuaries, National Parks etc. is equally applicable to marine reserves, marine
national parks and biosphere reserves.
The Gulf of Mannar Marine Biosphere Reserve (GOMMBR) has been notified
in 1989 through an executive communication from the Secretary to the Government of
India, Ministry of Environment and Forests to the Chief Secretary, Government of
Tamil Nadu.
During the operational phase of the project, the most important instrument to
be complied relates to the International Convention for the Prevention of Pollution from
Ships 1973 as modified by the Protocol of 1978 (MARPOL 73/78) for which India is a
signatory.
4.0 Key Findings
4.1 Environmental Status
4.1.1 Marine Environment

The Palk Bay and the Gulf of Mannar covering an area of 10,500 sq. km in
which the proposed ship channel is to be created are biologically rich and rated among
the highly productive seas of the world. Its diversity is considered globally significant.
In the Gulf of Mannar, between the coast line and the proposed alignment, there are
21 islands which have been declared as National Marine Parks by the Tamil Nadu
Forest Department and the MoEF, Government of India. While the proposed channel
alignment in the Tuticorin Port area shall be about
6 km from Van Tiu the nearest island, in Adam’s Bridge area it will be about 20 km
from Shingle Island which is a part of National Marine Park.
The data on physico-chemical characteristics and marine biological resources
was collected from various sampling stations in Gulf of Mannar and Palk Bay. Primary
data on physico-chemical characteristics of marine water shows no significant
variation in alkalinity (102-106 mg/l) and pH (8.0-8.2) along the proposed channel
alignment. The DO values varied from 3.2 to 5.7 mg/l and the silicates from 0.003 mg/l
to 0.017 mg/l. No significant variation in salinity is observed between surface and
bottom samples. An inverse relationship between salinity and silicates has been
observed. The nitrate concentrations vary from 0.78 mg/l to 1.1 mg/l. Data from
secondary sources in coastal areas of Palk Bay near Palk strait shows pH ~ 8.2, D.O.
5.8-6.5 mg/l and Total nitrogen content of 0.4 mg/l.
Sediment samples collected along the proposed channel alignment show the
presence of organic carbon, total nitrogen, total phosphorous and sulphates in
concentrations adequate for biological growth. Almost all the sediment samples show
presence of oil & grease. The concentrations of heavy metals are high in some of the
sediments in the Palk Bay as compared to other locations.
Biological Resources
The gross primary productivity along the proposed channel alignment vary
from 142 to 472 mgC/m3/day indicating that the Gulf of Mannar and the Palk Bay are
biologically productive regions. The zooplankton are dominated by copepod.
Macrobenthos represented by 78 varieties exhibit fairly good diversity. The meiofauna
comprised larval polychaetes, nematodes and worms.
The corals along the proposed channel alignment in Adam’s Bridge do not
exist though major groups of biological resources like sea fan, sponges, pearl oysters,

chanks and holothuroids at various sampling points have been recorded. In general,
the density of economically/ecologically important species along the proposed
alignment is not significant.
All the three groups of prochordata organisms, considered as the connecting
link between invertebrates and vertebrates, viz., hemichordata, cephalochordata and
urochordata comprising 1, 6 and 59 species respectively have been recorded around
the islands of the Gulf of Mannar.
There are 87 fish landing stations between the south of Point Calimere and
Pumban in the Palk Bay, and 40 stations in the Gulf of Mannar between Pamban and
Tuticorin. Out of over 600 varieties of fishes recorded in this area, 200 are
commercially important. During 1992-1996, the fish production has increased
gradually from 55,325 tonnes in 1992 to 2,05,700 tonnes in 2001.
Biodiversity
Non-conventional fishing in the region is represented by pearl, chank, sea
weeds, ornamental shells and holothurians. There has been a declining trend in the
production of these organisms as evidenced by the revenue received by MPEDA.
Rare and endangered species of sea turtle, dolphin, sea cow and whale are
recorded in the Gulf of Mannar and the Palk Bay. The sea cow inhabitates the shallow
shore regions where grasses occur, while other endangered animals mostly prefer
deep sea.
Several species of green algae (32), brown algae (35), red algae (59), blue
green algae (3) and sea grasses are recorded in the Gulf of Mannar and the Palk Bay.
A few of the 21 islands are reported to possess patches of mangroves predominated
by Avicennia sp. And Rhizophora sp.
Most of the habitats of the sensitive biota, viz., corals, pearl oysters, chanks,
sea cow, holothuroids and marine algae are along the coast and around the 21
islands, and mostly away from the proposed canal alignment.
Point calimore wild life sanctuary sprawling over 17.26 sq. km. Area
comprising tidal swamp, dry evergreen forests and mangroves is located in coastal
areas of Palk strait in Nagapattinam District. The sanctuary is bestowed with
population of varied wildlife such as Chital, Wild Bear, Bannet, Macaque, Black Buck,

Flamingoes, Teals, Gulls Tems, Plovers and Stilts, Dolphins and Turtles are seen
close to shore area.
4.1.2 Land Environment
Based on an analysis and interpretation of IRS IC LISS-III satellite data,
merged with PAN data, degraded area in Pamban island has been delineated for
anticipated disposal of dredged material to the extent possible with prior approval
under CRZ regulations. A large stretch about 753 hectare, of such land between
Rameshwaram and Dhanushkody is available.
There are no archaeologically significant structures along the proposed
channel alignment. However, there are apprehensions of encountering cultural/
archaeological artifacts during the excavation of the channel though borehole data
generated by the National Ship Design Research Centre (NSDRC) does not support
such a situation.
4.1.3 Socio-economic Environment
Along the coast in the Gulf of Mannar and the Palk Bay there are 138 villages
and towns belonging to 5 districts. The socio-economic profile of the
fishermen in the villages of Gulf of Mannar coast is low, and more than 40% of families
are in debt. The local people are of concern that the creation of channel would result in
the reduction of their income due to fishery.
4.2 Oceanographic Status
The hydrodynamic studies of the seabed in Adam’s Bridge and its adjoining
area have been carried out in May 2003 and February 2004 by retaining the services
of National Ship Design Research Centre (NSRDC), Vishakhapatnam. The
hydrographic charts bearing nos. 1584, 1586, 1587, 2069, 2197 and 96 have been
referred while conducting the surveys.
There are two circulations of water masses observed in the Bay of Bengal,
the clockwise circulation in south-west monsoon and the counter clockwise circulation
in the north-east monsoon. The tidal variations are between 0.05 to 0.7 m. The current
velocities in the Palk Bay and the Gulf of Mannar are as mild as 0.2 - 0.4 m/s except

on few days during south-west monsoon when it rises upto 0.7 m/s. Water currents
follow the directions of predominant winds. The analysis of current data shows no
potential threats to siltation of channel. It is observed that during southwest monsoon
the sediments move from Gulf of Mannar to Palk Bay and during fair weather the
direction reverses. In annual cycle, a net exchange of 6000 m3 of sediment is found to
move from Palk Bay to Gulf of Mannar through Pamban pass and 25000 m3 of
sediment moves from Gulf of Mannar to Palk Bay through Arimunai.
Geological strata in Adam’s Bridge area shows soft and hard sand upto 12 m
with particle size varying from 65 to 600 µm. The bathymetry varies from 0.6 to 6.3 m.
Depth in Palk strait averages to about 8 m.
The hydrographic survey of Palk Bay and Palk strait area has been carried
out during Jan. 25 - Feb. 18, 2004 by the Naval Hydrographic
Department of National Hydrographic Office (NHO). According to the findings of NHO,
the seabed in this region comprises of sand and mud with few broken shells. The
depth contours in the sea are in agreement with those depicted on the existing
navigational chart no. 358. While navigable depth (more than 12 m) will be used in
about 78 km stretch in Palk Bay, a sizable stretch (about 54 km) will require to be
dredged in Palk Strait and adjoining area. Subbottom profile studies indicate that
though the upper layer of sediment is made up of mud and sand, there is some hard
strata under the soft sediment. This hard strata if discovered to be rock, if would
require blasting at the time of dredging to achieve the desired draught.
The tides in the area are not similar. Both semi-diurnal and diurnal tides are
observed at the tidal station set up. The range of spring tides vary between 0.4 to 0.7
m. The current in the area is N-S direction with speeds varying from 0.08 to 0.8 m/s
and may reach 1.8 m/s (4 kt) in spring. No wrecks and obstruction have been
observed during the survey.
5.0 Impacts due to the Project
5.1 Impacts on Landbased Facilities
The project envisages construction of shore facilities to cater the needs of
channel in Adam’s Bridge area, viz. service jetties, slipways, buoy yard, repair
workshop as also staff and administration buildings for facilitating regulated traffic in
the vicinity of Adam’s bridge area. The locations of land-based structures, and the

extent of area required for their construction is required to be identified on Pamban
island in consultation with local authorities. Most of the land east of Rameshwaram is
barren and covered by sand and scant vegetation. There are few hamlets at Arimunai
and Dhanushkodi who are engaged in fishing. These fisherman will be displaced in the
event the land based facilities are planned in this area. Temporary displacement of
these fisherman is envisaged. A BSF check post will also be temporarily affected.
Land on Pamban island has also been identified for disposal of dredged material (silt /
clay / sand). The land cover, landuse as also the ownership of sites required for the
project related activities will be firmed up once the modus-operendi of traffic regulation
in channel is finalized. Hence, the extent of land acquisition, the need for resettlement
and rehabilitation of affected population, if any, can not be assessed at this juncture.
However, given the fact that channel will cut across the Adam’s Bridge area, the
impacts on land based facilities would be negligible in comparison to that envisaged in
earlier studies where land locked canal cutting through Pumban Island was proposed.
During the construction of the ship channel, it is anticipated that considerable
sea-borne activity in the form of logistic and support services would take place. This
would have significant adverse impact on the traditional fishing activities by the
licensed fisher folk and consequently on their income levels.
5.2 Impacts on Productivity and Ecology in GOM/Palk Bay
As the proposed alignment in Gulf of Mannar is more than 20 km away from
the existing 21 islands in National Marine Parks in the Gulf of Mannar, the marine
biological resources around these islands will not be affected to any significant level.
The existing level of primary productivity in the project area will remain
practically unaltered during the construction and operation phases of the channel.
There would not be any significant change in water quality including turbidity due to
the proposed deployment of cutter suction/trailor suction hopper dredgers for capital
and maintenance dredging.
Due to dredging the bottom flora and fauna on an area about 6 sq. km along
the channel alignment in Adams Bridge and about 16-17 sq.km in Palk Bay/Palk Strait
area will be lost permanently. This loss, however, will be very insignificant compared to
the total area of 10,500 sq. km of the Gulf of Mannar Marine Biosphere Reserve.

In Adam’s Bridge area about 38 million m3 of dredge spoil comprising about
7-8 million m3 clay silt will be generated for achieving 12 m depth for 300 m wide
channel including allowances for slope and tolerance. It is proposed that spoil
containing a mixture of clay and sand will be disposed on degraded areas of Pamban
island for reclaiming the land subject to approval of Forest and Environment
Department (TN) for use of area falling under CRZ as dumping of wastes in CRZ area
is not permissible activity. Balance 30 million m3 spoil containing mainly sand (particle
size 125 µm to 600 µm) will be discharged in sea 25 km away from the dredging area
keeping safe distance from medial line at depths varying from 30-40 m to minimise the
impact. In the event of restricting the channel to 10 m depth to suit vessels with 9.15 m
draught, the quantity of dredged spoil will reduce by 13.5 million m3 and material
required to be disposed in sea will be 16-17 million m3 instead of 30 million m3 as
envisaged for 12 m depth. This would further minimize impacts on sea bed due to
disposal of dredged spoil.
In Palk Bay area, about 44 million m3 of dredged spoil will be generated due
to excavation activity in Palk strait and Palk Bay to achieve 12 m depth for 300 m
channel including allowances for slope and tolerance. The NHO data indicate hard
strata beneth soft sand hence spoil may contain silt, sand and hard material. The
dredging may also require blasting if hard strata is encountered. In the event of
blasting, adverse impact on sea bottom fauna is envisaged. The spoil is proposed to
be discharged in Bay of Bengal at suitable depth (25-40 m) to minimize impacts on
coastal areas of Palk Bay. An option of using silt/clay for beach nourishment is also
recommended. In the event of restricting the channel depth to 10 m the requirement of
dredging in Palk Bay/Palk strait will drastically reduce to about 14.8 million m3 as
against 44 million m3 envisaged for 12 m depth. This would minimize environmental
impacts as well cost of dredging and disposal.
It would be ideal to explore the possibility of dredging the channel to 10 m
depth in first phase to cater to vessels of 9.15 m draught and monitor environmental
status during construction and operation phases. The proposal of 12.0 m depth can
subsequently be taken up in second phase provided adverse impacts on environment
are not observed.
Hydrodynamic modelling studies using Depth Integrated Velocity and Solute
Transport (DIVAST) model have shown that, even for the highest spring tidal water

conditions, there will be no significant change in the magnitude and direction of current
velocities along the proposed alignment due to the construction of the channel in
Adam’s bridge area.
During the construction and operation phases of the channel, the potential
sources of marine pollution are spillage of oil and grease, marine litter, jetsam and
floatsam including plastic bags, discarded articles of human use from the sea-borne
vessels which will have to be controlled.
The channel may facilitate the movement of fishes and other biota from the
Bay of Bengal to the Indian Ocean and vice versa. By this way, the entry of
oceanic and alien species into the Palk Bay and the Gulf of Mannar, as also the
dispersal of endemic species outside the Palk Bay and the Gulf of Mannar could
occur.
5.3 Socio-economic Impact
The channel will establish a continuous navigable sea route around
peninsular coast within the Indian territorial waters, reduce shipping distance by about
254-424 nautical miles and voyage time of about 21-36 hrs as also the attendant
operating costs. The channel will become a valuable asset from national defence and
security point of view enabling easier and quicker access between the coasts.
Due to the construction of infrastructure in the island, the land access, now
available to the local fisher folk to Dhanushkody area for traditional fishing will be
hindered unless alternative arrangements are made. The dredging and shipping
operations will have to be so regulated as to cause minimum disturbance to the
normal fishing activities.
The project will provide employment opportunities and avenues of additional
income through establishment of small ancillary industries. The project will also trigger
development of coastal trade between the ports south and north of Rameshwaram
consequently reducing the load and congestion on railways and roadways.
The project will help in saving considerable foreign exchange through
reduction in oil import bill and generate revenue income from dues levied on ships
transiting the channel which will add to the national economy.

6.0 Environmental Management Plan
6.1 Construction Phase
No dredging will be done in Gulf of Mannar except in Adam’s Bridge
–
area
Alignment of navigation route at Adam’s Bridge in Gulf of Mannar will be
–
minimum 20 km away from marine national park
Land acquired for mobilization and monitoring of activity will be returned
–
to users after completion of dredging activity
A proper rehabilitation plan for the fisherman at Dhanushkody will be
–
drawn during construction phase
Dredged spoil comprising clay and sand upto 2 m of dredging depth will
–
be used for reclaiming degraded land in Pamban island subject to
approval of FED for CRZ. Balance dredged spoil will be disposed in sea
at a depth 30-40 m, 20-25 km away from islands in National Marine
Park in Gulf of Mannar. Dredged spoil generated in Palk Strait / Palk
Bay area will be disposed in open sea in Bay of Bengal at
25-40 m depth, 30-60 km away from dredging area
Safe distance (about 4 km) from international medial line will be
–
maintained
During dredging activities, the equipments, vessels, barges required for
–
dredging and transportation of dredged spoil will be maintained in
secured area and spillage of oil or any toxic material including paints,
anticorrosive agents etc. will not be allowed to spill in sea/coastal waters
Movement of barges for transporting dredged spoil to land area will not
–
interfere with movement of fishing boats in both Gulf of Mannar and
Palk Bay region adjoining the Adam’s Bridge
It is also recommended that existing jetties at Rameshwaram which only
–
cater to fishing activities presently should be augmented to cater to the
requirement of handling dredging activities in Adam Bridge and Palk
Bay area
Transportation of heavy machinery and construction material in the
–

vicinity of Adam's Bridge will be by sea route using the available
navigational depths
During transportation of heavy equipments and machinery by road, care
–
will be taken to avoid traffic hazard, traffic congestion and if required
roads will be augmented to meet the conditions of hazard free
transportation.
6.2 Operational Phase
All the ships originating from Tutitcorin Port will comply to
–
International Maritime Standards and follow MARPOL convention
(MARPOL 73/78)
Discharge of bilge, ballast, treated sewage, solid wastes, oily
–
wastes and spillage of cargo will not be allowed in the Gulf of
Mannar and Palk Bay area
The traffic of crude oil tankers will be allowed in this route with
–
strict vigilance so as to avoid any possibilities of spillage in this
region
It will be ensured that ships navigating in this region should not
–
use such paints and anticorrosive agents on ship bottom which
can cause damage to marine organisms
A pilot should be trained or environmental watcher will board the
–
ship to watch marine animals viz. turtle, dolphins, sea cow etc. in
the region and navigate the ship safely avoiding any damage to
this fauna.
It will be ensured that all the ships berthing at TPT as well as all
–
those using the route without touching TPT will have proper
treatment facilities for sewage however discharge of treated
sewage will not be permitted in GOM and Palk Bay / Palk strait
area
Ships bypassing TPT and transiting the channel will be inspected
–
for its navigational safety measures before it is allowed to enter
proposed navigation route

An oil spill contingency plan will be drawn by Tuticorin Port Trust
–
with preparedness to prevent spread of spillage in Gulf of Mannar
and Palk Bay area and its immediate recovery by deploying
equipments and ships
To benefit large fishing communities in the coastal area of
–
Ramnathpuram and Rameshwaram, a corridor both in terms of
space and time be provided to fisherman to use the channel in
Adam’s Bridge area for moving across Palk Bay to GOM and vice
versa for fishing activity
The jetties at Rameshwaram are in dilapidated conditions. A
–
programme to construct a few Jetties at Pamban island to
augment fishing activity in the region be supported by TPT
The traffic of ships carrying crude oil will be handled with strict
–
vigilance so as to avoid possibility of spillage
The oil spill contingency plan in operation at TPT will be extended
–
to navigation activities in new channel
A pilot will board the vessel either from Rameshwaram or
–
appropriate place to navigate ship through GOM area up to
Bengal Channel in Palk Bay
The channel will be properly marked by navigational light buoys
–
Accidents by collision of ships with fishing boats will be totally
–
prevented by slowing down the cruise speed and also alerting the
fisherman by cautionary measures. During implementation and
operational phases of the project, TPT will take action to avoid the
collisions of ships with fishing boats or damage to fishing nets with
cooperation from fishing communities, Navy, Coast Guards and
other Govt. authorities
Suitable timings apart from ship transit will be given for fishermen
–
to continue with their fishing activities
Maintenance dredging of about 0.55 million m3 per year is
–
envisaged in the channel based on data available for sediment

transport across Palk Bay and Gulf of Mannar
The dredged material will be mostly silt and clay and will not be
–
disposed in sea. Instead it will be used to reclaim degraded areas
on Pamban island, Ramnad and Mandapam coastal stretches
To cater to increase in trade envisaged due to this project and to
–
transfer benefit to local fisherman, a minor port facility can be
created at Rameshwaram in consultation with state authorities
5.4 km
E4
14.4 km 10.5 m
E3
8.1 m
19.8 km E2
9.6 m
14.6 km
E1
E 11.6m
D
C
B Km : Distance between points
m : average depth within a section

Fig. 6.12 : Bathymetry along the Proposed Channel
Tirutturaippundi
Pattukkottai Karryappattinam
Muttupet Topputtural
Atirampattinam POINT CALIMER
Peravuruni North Channel
PALK STRAIT
E4
Tiruvayppadi E3
E2
E1
Manamelkudi
E
Point Pedro Shoa
Kottaippattanam
Point Pedr
Gopalapatnam
Sundarapandiyanpattana
6.33
Karaitivu NW Point
Tiruvadanai
Nakarkoy
Tiruvettriyur
D Chem
Kalmunal Pt.
Delft Channel
Moreppanai
Pooneryn
PALK BAY
Neduntivu Shoal
LEGEN
C :
Vallaipadu
E4 :
A
Uchipuli
E :
C
Mannar Island Near W Numbers :
Land End B
A
GULF OF MANNAR Talamannar
Parayanpiddy
Vidattaltivu
A1

Fig. 6.11: The Alignment of the Proposed Channel
6.36a
Fig. 6.14a : Tentative Location for Disposal of Dredge Materials in Sea
Proposed in 1961
Proposed in 1968
Proposed in 1996 Report
Suggested by Steering Committee
Considered by NEERI (1998)
Present Proposal of NEERI

6..58
Fig. 6.30 : Plan Showing Various Alignments of
Sethusamudram Ship Canal Project and
the Group of Islands (Marine Parks) in Gulf of
Mannar
4.10

4.11

4.13
4.12

Annexure I
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