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International Journal of Marine Science 2013, Vol.3, No.23, 178-186
http://ijms.sophiapublisher.com
182
and marine water influx from near by sea. Thus
intermixing of water from two different origins and
bearing produces a unique condition where salinity is
neither more like sea water or entire salt less like fresh
water. Thus a moderate salinity is formed better called
as “brackish water condition” and hence such
ecosystems are called as the transitional ecosystems as
they are influenced both from terrestrial side and
marine counterpart located on the coastal line called as
the coastal lagoon or in the form a riverine opening to
the sea called as estuary having shallow depth. Due to
this shallowness, sunlight mostly reaches to the
bottom and this helps to proliferate the bottom
vegetations such as sea grass, marine algae and other
fresh water macrophytes. A number of faunal species
are able live in different parts of the flora. It provide
essential habitat for growth of larvae of different fish
and shellfish. The SAV rich lagoon often serve as
nursery and feeding ground for a variety of organisms
especially for fishes, shell fishes and benthic
macro-invertebrtaes (Heck and Thoman, 1984; Duarte,
1995). The primary production are mostly depended
on benthic macro algae and vascular macrophytes, but
phytoplankton based primary production may be seen
in non-SAV regions. Hydrographically, coastal lagoon
posses three different gradient such as fresh water
zone (oligohalaine), marine water zone (euryhalaine)
and brackish water zone (mesohalaine). The overall
biodiversity and its distribution entirely depended up
on this zonatation made with respect to salinity regime.
Shallow coastal habitat can be treated as self sustained
unit because of the recycling of nutrient and organic
matter. The presence of SAV reduces the turbidity,
increases transparency and high solar attenuation
helps for growth of bottom vegetation. This increases
the amount of primary productivity in the aquatic
ecosystem. Wind and tide mediated wave action helps
to mix the cold oxygen & nutrient rich bottom water
with hot warm water hence vertical stratification is
interrupted. Tidal amplitude is less than one meter is
sufficient to maintain the brackish water characteristics.
In such shallow regions and exposed mud flats are
behaving as potential feeding, breeding and nesting
areas for birds. Bird’s plays very crucial role in lagoon
ecosystem as it feeds on submerged plants, benthic
macro-invertebrates and small fishes and provides
enormous amount excreta in during their congregation
period. These excreta contain good concentration of
nitrogen and phosphorus which is highly essential for
growth of macroalgae and phytoplankton. This
nutrient recycle is the significant feature of high
biodiversity rich areas such coral reefs and mangrove
vegetation (Barnes, 1980, 1994; Nybakken, 2003).
The cumulative impact all those parameters makes the
coastal lagoon as one of the most productive and
biodiversity rich region in the world vegetation
(Barnes, 1980; 1994; Alongi, 1998, Nybakken, 2003,
Anthony et al., 2009).
7 Problems Associated with Coastal Lagoon
vis-à-vis Future Challenges
Broadly, coastal lagoons are facing problem from two
different kinds of sources. Such as natural input and
anthropogenic input.
Natural stressors: This category of input is basically
driven by the from climate related problems like
flooding due to over precipitation or draught due to
less precipitation, sea-level rise, cyclone, super
cyclone, hurricanes and other major storms, shore line
change, long shore littoral drift. All these have cumulative
impact on physico-chemical biological property.
Anthropogenic stressors: Due to rapid population
growth, stress on coastal ecosystem increasing day by
day. Among the major detrital forces, pesticide
pollution sewage pollution, radionuclerides, oil spill,
sound pollution, coastal pollution, coastal aquaculture
and farming over use of motor boats for fishing
activity and tourism, eutrophication.
Depending upon increasing stress from natural and
anthropogenic resources Kennish (2002) identified 10
principal anthropogenic impacts on coastal wetland
ecosystems which are listed in Table 2. He later
modified this list, dividing it into the more serious
Tier
I stressors and the less threatening Tier
II
stressors (Kennish et al., 2008). The Tier
I stressors
can put more critical threat to the structural and
functional attribute of coastal ecosystem.
8 Chilika Lake–A Case Study
The Lake Chilika is located at the east coast of
ecosystem including mangroves, seagrass, seaweeds
and coral reef (Figure 3). Proper planning and
effective management of ecosystem can be achieved
by collecting data on these ecosystems by the
application of Remote Sensing techniques. Remote