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International Journal of Marine Science 2013, Vol.3, No.23, 178-186
http://ijms.sophiapublisher.com
183
Table 2 Principal anthropogenic impacts on coastal wetland ecosystems
Tier I Stressors
Tier II Stressors
Stressor
Impact
Stressor
Impact
Habitat loss and
alteration
Elimination of usable habitat for lagoonal
and estuarine biota
Chemical contaminants
Higher priority synthetic
organic compounds Lo-
wer priority—oil (PAHs),
metals, radionuclides
Adverse effects on estuarine organisms,
including tissue inflammation and
degeneration, neoplasm formation,
genetic derangement, aberrant growth
and reproduction, neurological and
respiratory dysfunction, digestive dis-
orders and behavioral abnormalities;
reduced population abundance; sediment
toxicity
Eutrophication Increased primary production, harmful algal
blooms, hypoxia and anoxia
,
increased benthic
invertebrate mortality, fish kills, altered
community structure, increased turbidity and
shading, reduced seagrass biomass, degraded
water quality
Freshwater diversions Altered hydrological, salinity, and
temperature regimes; changes in
abundance, distribution, and species
composition of estuarine organisms
Sewage and org-
anic wastes
Elevated human pathogens, increased nutrient
and organic matter loading, increased eutrop-
hication, increased hypoxia, degraded water
and sediment quality, reduced biodiversity
Introduced/invasive
species
Changes in species composition and
distribution, shifts in trophic structure,
reduced biodiversity, introduction of
detrimental pathogens
Fisheries over-
exploitation
Depletion or collapse of fish and shellfish
stocks, altered food webs, changes in the
structure, function, and controls of estuarine
ecosystems
Subsidence
Modification of shoreline habitat,
degraded wetlands, accelerated fringe
erosion, expansion of open water
habitat
Sea
-
level rise
Shoreline retreat, loss of wetlands habitat,
widening of estuary mouth, altered tidal prism
and salinity regime, changes in biotic community
structure
Sediment
input/turbidity
Habitat alteration, reduced primary
production, shading impacts on ben-
thic organisms
Storms and Hur-
ricanes (Kennish
et al., 2008).
Increased nutrient, sediment, organic matter and
contaminant loading, increased hypoxia,
salinity stress on primary producers and
higher trophic levels, altered water residence
time with potentially adverse effects on flora
and fauna
Floatables and debris
(Kennish et al. 2008).
Increased mortality of seabirds, mar-
ine mammals, reptiles, and other
animals.
sensing technology contemplates collection of spatial,
spectral and temporal data of earth surface using air
and space crafts. It is largest brackish water lagoon of
Asia. This lake is regarded as an important Ramsar
site because of its great biodiversity and rich
exploitable fishery resources that helps for more 0.2
million of fishermen depending op on it. The brackish
water character of Chilka Lake is basically due to the
mixing of fresh water derived from more than 50 no.
of rivers and rivulets from northern Mahanadi Delta
and western catchment area and marine water
intrusion from Bay of Bengal from the eastern side
through couple of inlets. Lake area is varied between
906 sq.km in summer and 1 165 sq.km during
monsoon. According to the salinity distribution, the
lake ecosystem is further sub-divided in to four
ecotones
such as
northern sector- it is mostly fresh
water but became brackish water during the summer
season due to less reverine flux. Central sector posses
true brackish water condition where as southern sector
behaves like brackish water to marine kind of
condition during summer while outer channel region
which exhibited like an estuarine system is typically
marine kind of ecosystem often tidally influenced
from Bay of Bengal but the surface water turns fresh
during Monsoon because of outflux of huge amount of