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International Journal of Marine Science 2013, Vol.3, No.23, 178-186
http://ijms.sophiapublisher.com
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act as a reservoir. Tidal variation is usually less and
salinity level is quite variable, posses less life span of
few decades only.
(c) Silled lagoons: Less tidal variation was marked,
thus water became stagnant hence seasonal variation
is observed.
(d) Sluiced lagoons: It is formed due to the formation
of artificial structures such as sluice gates or culverts
with the nearby sea or ocean.
(e) Lagoonal inlets: In this type of lagoons the entry of
seawater is possible through inlets. Some portion of
this lagoon is influenced with the tidal variation and
salinity level is usually in sea ward site and other
regions are influenced by fresh water intrusion thus a
typical brackish water condition is prevailed. Sharp
seasonal variation was marked and acts as repository
of great biodiversity e.g. Chilka Lake.
3 Origin and Distribution of Coastal Lagoon
Geologically, the coastal lagoons are considered as
unstable and ephemeral environments. According to
the observations of Curray et al (1969), Phelger
(1969), Mee (1978) these transitional zones are
developed during the Holocene sea level rise that
occurred about 6000~8000 years ago. On a geologic
time scale, coastal lagoons are short-lived landscape
features with an essentially linked connection with sea
and continental land mass that provides fresh water,
they can act as filtering units and may be the
appropriate answer the global warming and climate
change (Anthony et al., 2001).
These transitional ecosystems ecologically most
significant ecosystems are distributed unevenly and
widely ranged from tropic to sub-polar regions
(Nicholas and Allen, 1981) occupying ~13% of the
total coast line of the globe (Cromwell, 1971; Kjrefv,
1996; Troussellier, 2007). Many other environments
which are considered similar to lagoonal ecosystem
are the mangrove Islands and barrier reefs (Sourina
and Richard, 1975) etc. About 17.6% of world's
coastline bearing coastal lagoon are found in North
America, as against 12.2% in South America, 5.3% in
Europe, 17.9% in Africa, 13.8% for Asia, and 11.4%
in Australia (Cromwell, 1971; Barnes, 1994).
Indian has coast line of 8 000 sq km covering Bay of
Bengal, Arabian Sea and Indian Ocean and endowed
with many of coastal lagoons, estuaries, mangroves
mudflats etc. There are 17 no. of coastal lagoon has
been observed from both coast of India out of which
eight on east coast and nine on west coast as depicted
from Table 1 and Figure 2.
Table 1 17 coastal lagoons located on coastal region of India
East coast
West Coast
Chilika lagoon
Vembanad lagoon
Pulicat lagoon
Ashtamudi lagoon
Pennar lagoon
Paravur lagoon
Bendi lagoon
Ettikulam lagoon
Nizampatnam lagoon
Murukumpuzha lagoon
Muttukadu lagoon
Veli lagoon
Muthupet lagoon,
Talapady lagoon
Gulf of Mannar lagoons
Lagoons of the Mumbai
Lagoons of Lakshadweep
4 Significant Information Regarding Coastal
Lagoon
There are certain noteworthy features associated with
the coastal lagoon. These are as follows:
Coastal lagoons shallow and well mixed by wave and
current.
Average depth in general, is less than 2 m , though
more depth is recorded at channel and near by areas of
inlet.
Tidal regime is less than 2 meter, thus microtidal in
nature.
The photic zone of coastal lagoon extends to most of
the seafloor.
Strong benthic pelagic copling de to primary
production at benthic level and in pelagic interaction
and nutrient cycling (McGlathery et al., 2007).
Recycling of the nutrients with in the lagoon premises
de to long resistance period of water.
Annual primary production in coastal lagoons
generally ranges from ~50 to >500 g C m–2 yr–1.
Based on trophic status, coastal lagoon may be
eutrophic (primary production 300 to 500 g C m–2
yr–1), mesotrophic (primary production 100 to 300 g
C m–2 yr–1) and oligotrophic (primary production
<100 g C m–2 yr–1) conditions (Nixon, 1995).
Highest primary production is associated with sea grass