Nayana.P and Jitendra Kumar
College of fisheries
Wetland degradation is the impairment of
wetland functions as a result of human
“Wetland degradation” is a direct humaninduced impact resulting from wetland
conversion to a specific sectoral or multisectoral economic use, causing an
increase in GHG emissions and loss of
Wetland loss is the loss of wetland area,
due to the conversion of wetland to nonwetland habitats, as a result of human
The United States alone has lost more
than half of its original wetlands, and we
continue to lose over 100,000 wetland
acres a year.
wetland loss has been occurring for
thousands of years
Lowland rice cultivation began in SE Asia
about 6,500 years ago
no trace remains of the natural floodplain
wetlands of the Red River delta in
Vietnam, which originally covered 1.75
virtually nothing left of the one million
hectares of natural floodplain vegetation
which once covered most of the Sylhet
Basin in Bangladesh
Much of the 40 million hectares of rice
cultivation in the central plains of India
must have been developed at the expense
of natural wetlands
Major Effects of Wetland
50% loss of spawning grounds for fish
50% loss of waterfowl habitat
50% loss of flood control capability
50% loss of erosion control and
Why So Much Wetland Loss?
Perception of wetlands as
“wastelands” and “swamps”
Economic incentives for
development and urban sprawl
of Wetland Loss &
A) Biological Alterations
B) Chemical Alterations
C) Physical Destruction or
A) Biological Alterations
1. Removal of wetland or riparian
( the interface between land and a river
or stream )vegetation
2. Introduction of non-native/exotic
Removal of riparian
vegetation next to
stream due to
Farming up to edge of stream.
Livestock corral adjacent to stream
and non-native plants,
i.e. purple loosestrife
need to be controlled
or prevented by proper
land management, i.e.
1. Release of pollutants & toxic
2. Change in nutrient levels
Agricultural runoff carries pesticides, fertilizers
Livestock corral on streams allows manure
(nutrients) to enter stream unfiltered by vegetation.
Sediment plume discharging into river
and then entering lake.
3. Dredging & Stream Channelization
4. Peat Mining
5. Flooding & Changes in Sediment
Deposition Patterns due to Dam
6. ATV/Recreational Uses
Stream channelization = straightening of rivers
& streams for railroad and highways.
Flooding (and flood damage) is much greater
when streams are straightened and riparian
vegetation has been removed.
Michigan is largest peat producer.
Other large peat producers are: Florida,
Illinois, Indiana, and Minnesota
Peat land crop production (sod, carrots,
onions, celery, potatoes, lettuce,
cranberries, mint, radishes.
Horticultural use; containerized
seedlings used in forest industry.
Impact of Wetland Loss
Wetland acreage has diminished to the
point where environmental and socioeconomic benefits (i.e., ground water
supply and water quality, shoreline
erosion, floodwater storage and trapping
of sediments) are now seriously
Role of wetlands in global climate
change currently being debated