Wetland destruction

Wetland Wetland destruction :destruction :causes and causes and consequencesconsequences

Nayana.P and Jitendra KumarNayana.P and Jitendra KumarDept.of FRM Dept.of FRM College of fisheriesCollege of fisheries

[email protected]@gmail.com

Introduction Introduction

Wetland degradation is the impairment of Wetland degradation is the impairment of wetland functions as a result of human wetland functions as a result of human activity.activity.

““Wetland degradation” is a direct human-Wetland degradation” is a direct human-induced impact resulting from wetland induced impact resulting from wetland conversion to a specific sectoral or multi-conversion to a specific sectoral or multi-sectoral economic use, causing an sectoral economic use, causing an increase in GHG emissions and loss of increase in GHG emissions and loss of carbon stocks.carbon stocks.


Wetland LossWetland Loss

Wetland loss is the loss of wetland area, Wetland loss is the loss of wetland area, due to the conversion of wetland to non-due to the conversion of wetland to non-wetland habitats, as a result of human wetland habitats, as a result of human activity.activity.

The United States alone has lost more The United States alone has lost more than half of its original wetlands, and we than half of its original wetlands, and we continue to lose over 100,000 wetland continue to lose over 100,000 wetland acres a year.acres a year.


AsiaAsia

27%27% wetland loss has been occurring for wetland loss has been occurring for

thousands of years thousands of years Lowland rice cultivation began in SE Asia Lowland rice cultivation began in SE Asia

about 6,500 years ago about 6,500 years ago no trace remains of the natural floodplain no trace remains of the natural floodplain

wetlands of the Red River delta in wetlands of the Red River delta in Vietnam, which originally covered 1.75 Vietnam, which originally covered 1.75 million hectares million hectares


Cont,…Cont,…

virtually nothing left of the one million virtually nothing left of the one million hectares of natural floodplain vegetation hectares of natural floodplain vegetation which once covered most of the Sylhet which once covered most of the Sylhet Basin in Bangladesh Basin in Bangladesh

Much of the 40 million hectares of rice Much of the 40 million hectares of rice cultivation in the central plains of India cultivation in the central plains of India must have been developed at the expense must have been developed at the expense of natural wetlands of natural wetlands


MajorMajor EffectsEffects ofof Wetland Wetland LossesLosses

50% loss of spawning grounds for fish50% loss of spawning grounds for fish

50% loss of waterfowl habitat50% loss of waterfowl habitat

50% loss of flood control capability50% loss of flood control capability

50% loss of erosion control and 50% loss of erosion control and

sediment-trapping capabilitysediment-trapping capability


Why So Much Wetland Loss?Why So Much Wetland Loss?

Perception of wetlands as Perception of wetlands as “wastelands” and “swamps” “wastelands” and “swamps”

(= ignorance)(= ignorance)

Economic incentives for Economic incentives for development and urban sprawldevelopment and urban sprawl


Major CausesMajor Causes of Wetland Loss & Degradationof Wetland Loss & Degradation

A) Biological Alterations A) Biological Alterations

B) Chemical AlterationsB) Chemical Alterations

C) Physical Destruction orC) Physical Destruction or

DegradationDegradation


A) Biological AlterationsA) Biological Alterations

1. Removal of wetland or riparian (1. Removal of wetland or riparian ( the the interface between land and a river or interface between land and a river or streamstream ) )vegetationvegetation

2. Introduction of non-native/exotic 2. Introduction of non-native/exotic speciesspecies


Removal of riparian vegetation next to stream due to residential development.


Farming up to edge of stream.


Livestock corral adjacent to [email protected]@gmail.com

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.


Chemical AlterationsChemical Alterations

1. Release of pollutants & toxic 1. Release of pollutants & toxic

chemicalschemicals

2. Change in nutrient levels2. Change in nutrient levels


Agricultural runoff carries pesticides, fertilizers and manure.


Livestock corral on streams allows manure (nutrients) to enter stream unfiltered by [email protected]@gmail.com

Sediment plume discharging into river and then entering [email protected]@gmail.com

Physical Destruction Physical Destruction or Degradation_____or Degradation_____

1. 1. FillingFilling

2. Draining2. Draining

3. Dredging & Stream Channelization3. Dredging & Stream Channelization

4. Peat Mining4. Peat Mining

5. Flooding & Changes in Sediment 5. Flooding & Changes in Sediment Deposition Patterns due to Dam Deposition Patterns due to Dam Construction.Construction.

6. ATV/Recreational Uses6. ATV/Recreational Uses [email protected]@gmail.com

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.


Peat MiningPeat Mining Michigan is largest peat producer.Michigan is largest peat producer.

Other large peat producers are: Florida, Other large peat producers are: Florida, Illinois, Indiana, and MinnesotaIllinois, Indiana, and Minnesota

Peat land crop production (sod, carrots, Peat land crop production (sod, carrots, onions, celery, potatoes, lettuce, onions, celery, potatoes, lettuce, cranberries, mint, radishes.cranberries, mint, radishes.

Horticultural use; containerized Horticultural use; containerized seedlings used in forest industry.seedlings used in forest industry.


Impact of Wetland LossImpact of Wetland Loss

Wetland acreage has diminished to the Wetland acreage has diminished to the point where environmental and socio-point where environmental and socio-economic benefits (i.e., ground water economic benefits (i.e., ground water supply and water quality, shoreline erosion, supply and water quality, shoreline erosion, floodwater storage and trapping of floodwater storage and trapping of sediments) are now seriously threatenedsediments) are now seriously threatened

Role of wetlands in global climate change Role of wetlands in global climate change currently being debatedcurrently being debated


Wetland destruction

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