The Gulf of Mannar is a large shallow bay forming part of the Laccadive Sea in the Indian Ocean. It lies between the southeastern tip of India and the west coast of Sri Lanka. 20 islands are running almost parallel to the coastline of the Gulf of Mannar. Among them, Mandapam group of islands (Hare, Manoli, Manoliputti, Poomarichan, Pullivasal, Krusadai, and Shingle) are one of the richest coastal regions for biodiversity in Asia. An ecological study for the conservation of the biodiversity in these islands was done from the year 2009 to 2010. Each island has its unique characteristics, of biodiversity surrounded by coral reefs. The littoral, mangrove, tidal swamp, dry deciduous and scrubs insular forests of the islands hold a diversified faunal assemblage. The predominant existing plant species of the island are the mangroves (Rhizophora mucronate pair, Avicennia marina (Forssk.)Vierh, Ceriopstagal (perr.)Rabins) and deciduous and scrub species (Pandanus fascicularis, Thespesia populnea, Tamarindus indica, Cordia subcordata, Pithecolobium dulce, Ficus benghalensis, Pleurostylia opposite, Acacia planifrons, Salvadora persica, and Zizyphus nummularia) Pemphis acidula (Lythraceae family of flowering herb) is the note worthy endemic plant species. These floras for their propagation totally depend on the Hymenopteran and Lepidopteran diversity of insects and the sun bird for pollination and Mammals and Aves for seed dispersal. This study on the animal - plant interaction helps a lot in the formulation of action plan for biodiversity conservation in Mandapam group of islands.

1. Good Morning

2. “An Investigation on the Impact of Plant-Animal
Interactions in the Conservation of Insular
Biodiversity of Mandapam group of Islands”

3. • Variety of plants and animals
and other living things in a
particular area or region.
• Number or abundance of
different species living within
a particular region.
Biodiversity

4. Why Biodiversity is Important?
Biodiversity is the key indicator of the
health of an ecosystem.
A healthy biodiversity
offers many natural services for everyone
 Maintains Ecosystem services
 Protects individual species
 Preserves habitat and ecosystems

5.  Major ecosystem services are supported by
the direct interactions between plant and
animals, such as herbivory, pollination and seed
dispersal.
 Insects, Reptiles, Birds and Mammals are the
“ Keystone mutualists’’ bio – Agents of the
faunal population.
 These interactions play a key role in the
development of forest ecosystem.

7. The Gulf of Mannar Biosphere Reserve includes four group of
Islands consisiting of a total of twenty-one islands, Among
the 21 islands;
Seven islands belong to Mandapam group and another
seven islands belong to Keelakarai group, three islands to
Vembar group, and the remaining four islands to Tuticorin
group.
Mandapam group of islands includes Hare, Manoli,
Manoliputti, Poomarichan, Pullivasal, Krusadai, and Shingle
Islands.
All the seven Islands of the Mandapam group of islands
of Gulf of Mannar are selected for the study.

9. Map1: Location of 21 islands in the Gulf of Mannar Biosphere Reserve

10. 129.04
25.92.34
16.58
29.95
65.8
126.9
Hare Island Manoli Island Manoliputti Island Poomarichan Island
Pullivasal Island Krusadai Island Shingle Island
Figure 1 : Area wise Distribution of the study Islands (in Hectares)

11. 129.04
25.92.34
16.58
29.95
65.8
126.9
Hare Island Manoli Island
Manoliputti Island Poomarichan Island
Pullivasal Island Krusadai Island
Shingle Island
Map1: Location of 21 islands in the Gulf of Mannar Biosphere Reserve
Figure 1 : Area wise Distribution of the
study Islands (in Hectares)

12. Plate1: Shows the Study area of the Mandapam Group of Islands

13. Vegetation sampling Was done by quadrate method in each
of the forest type (1acre sq.met.)
Insect sampling Day time in butterflies
Was done during Night time by light
trap in moths
Observations were carried out in the morning hrs from
6.30 to 8.30 am when the butterfly activities were higher.
Insect sampling was done by using various methods
Butterfly netsHand gathering

14.  Bird visitors sampling was done during day
time.
 Observations were carried out during from
morning hours When the bird feeding activities
were higher.
 The field work was also done during the
night hours when the bat activities were higher.
Identification of the bat species was done by using
standard bat-capturing techniques.
 The micro chiropteran bat’s food selection
(mostly the insect pest of the island flora) is
identified through the faecal-pellet analysis.

15. Plate 2: Methodology used for
Data collection

16. Pollination is a very important part of the
life cycle of plants. Pollination is a necessary step
in the reproduction of flowering plants, resulting in
the production of offspring that are genetically
diverse.
Pollination is the process by which pollen is
transferred in plants, thereby enabling fertilization
and sexual reproduction.
Only cross pollination can enhance the
Bio-diversity of the forests due to the resultant
inter and intra specific hybrids.

18. Plate 2a: Common Mutualistic Butterflies
available in the Mandapam group of Islands

19. Plate: 2b Common Mutualistic Insect Species available in
Mandapam Group of Islands
Plate: 2c Lepidopteran interacting Plant
Species

20. 17%
17%
33%
12%
21%
Hesperidae Lycaenidae Nymphalidae
Figure 2a: Percentage of Interacting Insect
Orders in the Mandapam group of islands
Order Lepidoptera Tops the
Rank in Number and Variety.
Other predominant orders
include Hymenoptera, Coleoptera and
Hemiptera is the maximum in terms of
ecosystem services via pollination.
Figure 2b: Percentage of Lepidoptera species
family-wise interaction in the Mandapam Group
of Islands
Among the Lepidopterans the
family Nymphalide ranks the highest.
The Lycanidae, Hesperidae and
Papilionidae take the second place of family
wise interaction in the Mandapam group of
Islands.

21. Apocynaceae
7%
Arecaceae
4%
Asclepiadaceae
3%
Boraginaceae
6%
Caesalpiniaceae
6%
Celastraceae
5%
Euphorbiaceae
7%
Malvaceae
8%
Meliaceae
8%
Mimosaceae
6%
Moraceae
9%
Pandanaceae
5%
Papilionaceae
5%
Rhizophoraceae
9%
Salvadoraceae
4%
Verbenaceae
8%
Figure 2c: Percentage of Insect interaction with Island focal
plant families
The plant family of Moraceae and Rhizophoraceae
families’ (each 9%) records high percentage of insect
visitors compared to others.

22. Figure 3: Percentage of Bird interaction with
Island focal plant families
Apocynaceae
3%
Arecaceae
5%
Asclepiadaceae
6%
Boraginaceae
2%
Caesalpiniaceae
6%
Celastraceae
7%
Euphorbiaceae
11%
Malvaceae
6%
Meliaceae
4%
Mimosaceae
32%
Moraceae
4%
Rhizophoraceae
4%
Salvadoraceae
4%
Verbenaceae
6%
The plant family Mimosaceae (32%) and
Euphorbiaceae (11%) are the highly bird interacted
plant families compared to other focal plant families.

23. Figure 4: Percentage of Bat interaction with Island focal plant families
Among the
plant families
Mimosaceae (16%) and
Salvadoraceae (11%)
records highest
interactions with bats
compared to other plant
families.
The study results reveal that insects are good
pollinators of focal trees and are responsible for
other floral diversity of the Mandapam group of
islands.

24. Chapter I: Study on the Major Plant-Animal Interactions:
 Seed Dispersers of the Island Ecosystem
 The process of movement or transport
of seeds away from the parent plant is
called as “Seed dispersal”.
 Birds and Bats are important seed
dispersers of the Island Ecosystem.
 Birds often fly far away from the parent
plant and disperse the seeds in their
droppings.
 Fruit bats play an important ecological
role, particularly as agent of seed
dispersal.

25. Some tropical fruit bats carry
seeds inside them as they digest
the fruit, then excrete
the seeds far away from the
original tree.

26. Plate 3a: Observed Common Bird Visitors to the
Focal Trees in the Mandapam Group of Islands

27. Plate 4a: Ecological classification of avian fauna in the Mandapam group of Islands:
Birds based on their food and feeding habits

28. Plate 5: Available Bat
Species in the Mandapam
Group of Islands
Insectivores Carnivore

29. Figure 5: Percentage of Avian faunal visitor’s - Family-wise composition
in the Mandapam group of Islands
Among the 13 families of birds identified in the study area the Ardeidae
(18%), Accipitridae and Corvidae (12%) shows the highest percentage of
composition followed by other bird families.

30. Figure 6: Percentage of Ecological Groups Observed in the
Mandapam Group of Islands
Composition of Water birds and Predatory birds is the highest (29%) followed by
Frugivore birds (20%), Insectivore and Carnivore birds (15%), Omnivore and
Granivore birds (9%) and Nectarivore birds (3%).

31. 0%
10%
20%
30%
40%
50%
60%
70%
Insectivore bats Frugivore bats Nectarivore bats Carnivore bats
66 %
21 %
8 % 5 %
Figure 7: Bat Species observed in the Mandapam group of Islands
Insectivore bat species is found to be highly interactive when compared
to other bat species in the Mandapam group of Islands.

32. Figure 8: Percentage of Bird Interacting Plant families in the
Insular Forests
This figure clearly shows that the plant family of Mimosaceae
(19%) and Euphorbiaceae (11%) are the highest interactive
plant families when compared to other plant families.

33. Figure 9: Percentage of Bat Interacting Plant families in the
Insular Forests
This figure clearly shows that the plant family of Mimosaceae (17%),
Moraceae (14%), Myrtaceae and Boraginaceae (12%) are high
interactive plant families when compared to other plant families
identified in the study area.

34.  The diversity of the plant species is important
for all animals including herbivores and
omnivores.
 The plant species also provides food, shelter
and protection to other life in the forest.
 Trees provide habitats for a variety of
animals. Birds and bats use the holes for
storing food, as a shelter or for building nests
for their young ones.

35. The insular forest includes the Dry deciduous forest, Tidal swamp forest, scrub
insular forest, Littoral forest and Mangrove forest.

36. Apocynaceae
8% Arecaceae
6%
Asclepiadaceae
3%
Boraginaceae
9%
Caesalpiniaceae
4%
Celastraceae
4%
Euphorbiaceae
7%Malvaceae
6%
Meliaceae
6%
Mimosaceae
11%
Moraceae
5%
Pandanaceae
6%
Papilionaceae
5%
Rhizophoraceae
8%
Salvadoraceae
7%
Verbenaceae
5%
Figure 10a: Insect preferred tree families and the percentage of
their interaction in the Mandapam Group of Islands
Among the 16 families, Mimosaceae (11%) shows the
highest percentage of interaction when compared to other
plant families identified in the study area.

37. Apocynaceae
4% Arecaceae
10%
Asclepiadaceae
5%
Boraginaceae
11%
Caesalpiniaceae
5%
Celastraceae
5%Euphorbiaceae
6%
Malvaceae
5%
Meliaceae
5%
Mimosaceae
15%
Moraceae
4%
Pandanaceae
2%
Papilionaceae
3%
Rhizophoraceae
7%
Salvadoraceae
7%
Verbenaceae
6%
Figure 10b: Bird preferred tree families and the percentage of their interaction in
the Mandapam Group of Islands
Among them Mimosaceae (15%) shows the highest percentage of
interaction followed by Boraginaceae (11%), Arecaceae (10%),
Rhizophoraceae and Salvadoraceae (7%) and other plant families
identified in the study area.

38. Amaranthaceae
4% Asclepiadaceae
9%
Avicenniaceae
8%
Cactaceae
9%
Capparaceae
7%
Chenopodiaceae
6%
Euphorbiaceae
5%Goodeniaceae
6%
Lythraceae
7%
Papilionaceae
6%
Rhamnaceae
7%
Sapindaceae
7%
Solanaceae
4%
Surianaceae
8%
Verbenaceae
7%
Figure 10c: Insect preferred shrub families and their percentage of interaction in the
Mandapam Group of Islands
Among the shrub families, Asclepiadaceae and Cactaceae
(9%) receives the highest percentage of insect visitors when
compared to other plant families identified in the study area.

39. Apocynaceae
3%
Arecaceae
10%
Asclepiadaceae
3%
Avicenniaceae
3%
Boraginaceae
7%
Caesalpiniaceae
3%
Celastraceae
3%
Combretaceae
3%
Euphorbiaceae
3%
Malvaceae
3%
Meliaceae
3%
Mimosaceae
17%
Moraceae
7%
Myrtaceae
3%
Pandanaceae
3%
Papilionaceae
3%
Rhamnaceae
3%
Rhizophoraceae
7%
Salvadoraceae
3%
Verbenaceae
3%
Figure 10d: Bird preferred shrub families and their percentage of interaction in the
Mandapam Group of Islands
Among the Bird preferred shrub families Mimosaceae (17%)
receives the highest percentage of bird visitors.

40. Apocynaceae
3%
Arecaceae
10%
Asclepiadaceae
3%
Avicenniaceae
3%
Boraginaceae
7%
Caesalpiniaceae
3%
Celastraceae
3%Combretaceae
3%
Euphorbiaceae
7%
Malvaceae
3%
Meliaceae
6%
Mimosaceae
17%
Moraceae
7%
Myrtaceae
3%
Pandanaceae
3%
Papilionaceae
3%
Rhamnaceae
3%
Rhizophoraceae
7%
Salvadoraceae
3%
Verbenaceae
3%
Figure 11: Percentage of Mutualistic Plant and Animal interaction of tree species
Family-wise composition in the Mandapam group of Islands
Among the 16 families, Mimosaceae (17%) records
the highest percentage of composition.

41. Plate 6: Investigation on Focal plant species by the
researchers

42. Plate 6a - c : Photographic documentation of tree species and their
Mutualistic interaction with bio-agents in the Islands

43. All 29 tree species showed a high
level of interaction with all the
common Insectivorous, Nectarivorous,
Frugivorous, Predatory and Habitat
dwelling faunal members belonging to
the arthropod, avian and mammalian
family.
Among the animal visitors, the
interaction of insects and birds
shows a great level of
accomplishment and pollination
and seed dispersal are done by bird
and bat families.

44. CHAPTER-III : Conservation status and suggestions for the
maintenance of Island Biodiversity
World’s threatened biodiversity.
Habitat degradation and loss.
Exploitation of natural resources .
Intentional or accidental introduction of alien invasive species.
Flowering and fruit bearing phenology due to climatic
changes.
Increasing the insular forest coverage will reduce global
warming, tsunami, storm etc., and also help in the islands
biodiversity conservation.

45. Figure 12: Animal – Plant interactions in the Mandapam Group of Islands
Insects, reptiles, birds, and small mammals are the
‘keystone mutualists” of the island faunal population. Interactions
of insect (32%) and bird (22%) varieties of the island are the
maximum rank when compared to the other animals. Insects,
outnumbers all the faunal members by way of pollination
interaction. Reptiles and small mammals are the major predators
of the island that keeps control of the insect growth.

46. Habitat destruction
Collection of dead wood
Human Interference
invasive species (invaders like
prospsis )
Human settlement

47.  Plant and animal interaction is very important for
the restoration of the forest.
 Pollinators play a vital role in creating and
maintaining the habitats and ecosystems .
 Avian seed dispersal and bat seed dispersal are
important in the maintenance of the forest
diversity.
 An Increase in the population of Pollinators and
Seed dispersers is an indication of increase in plant
diversity and the other dependent fauna's diversity.

48. Afforestation - Planting ‘Favorite Plants of
Pollinators and Seed dispersers’ in the barren
land is recommended to conserve the
native biodiversity of the island.

49. Tamil Nadu
Forest
Department for
granting
permission and
field assistance
GOMBRT for Financial assistance