1. Wetland
destruction :
causes and
consequences
Nayana.P and Jitendra Kumar
Dept.of FRM
College of fisheries
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2. Introduction
 Wetland degradation is the impairment of
wetland functions as a result of human
activity.
 “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
carbon stocks.
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3. Wetland Loss
 Wetland loss is the loss of wetland area,
due to the conversion of wetland to nonwetland habitats, as a result of human
activity.
 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.
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4. Asia
 27%
 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
million hectares
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5. Cont,…
 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
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6. Major Effects of Wetland
Losses
 50% loss of spawning grounds for fish
 50% loss of waterfowl habitat
 50% loss of flood control capability
 50% loss of erosion control and
sediment-trapping capability
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7. Why So Much Wetland Loss?
 Perception of wetlands as
“wastelands” and “swamps”
(= ignorance)
 Economic incentives for
development and urban sprawl
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8. Major Causes
of Wetland Loss &
Degradation
A) Biological Alterations
B) Chemical Alterations
C) Physical Destruction or
Degradation
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9. 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
species
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10. Removal of riparian
vegetation next to
stream due to
residential
development.
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11. Farming up to edge of stream.
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12. Livestock corral adjacent to stream
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13. Introduced weeds
and non-native plants,
i.e. purple loosestrife
need to be controlled
through biological,
chemical and/or
mechanical means
or prevented by proper
land management, i.e.
minimize disturbance.
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14. Chemical Alterations
1. Release of pollutants & toxic
chemicals
2. Change in nutrient levels
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15. Agricultural runoff carries pesticides, fertilizers
and manure.
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16. Livestock corral on streams allows manure
(nutrients) to enter stream unfiltered by vegetation.
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17. Sediment plume discharging into river
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and then entering lake.

18. Physical Destruction
or Degradation_____
1. Filling
2. Draining
3. Dredging & Stream Channelization
4. Peat Mining
5. Flooding & Changes in Sediment
Deposition Patterns due to Dam
Construction.
6. ATV/Recreational Uses
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19. Stream channelization = straightening of rivers
& streams for railroad and highways.
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20. Flooding (and flood damage) is much greater
when streams are straightened and riparian
vegetation has been removed.
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21. Peat Mining
 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.
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22. 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
threatened
 Role of wetlands in global climate
change currently being debated
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23. jitendranduat@gmail.com