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International Journal of Marine Science 2014, Vol.4, No.47, 1-11
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8
mix of macrobenthic organisms, but the benthic
biodiversity is within the safe level in Vellar estuary. It
was quite evident by the multivariate analysis
RELATE showed Spearman rank correlation (Rho)
value (0.513) and it formed outside the graph to
explain the seriation of species composition in the
present study.
McLusky et al. (1975) suggested that the monsoon
may adversely affect the macrofaunal population by
reducing the salinity and altering the bottom profile. It
has also been suggested by Achuthankutty (1976) that
serve erosion of the intertidal area may limit the
substratum for sand dwellers. In the present study,
infaunal macrofauna observed to be reduced in density
during monsoon season. Maximum density of fauna
was observed during the summer and premonsoon
seasons due to both high productivity and increased
rate of breeding (Damodaran, 1973).
The present study concluded that the temporal
distribution of benthos exhibited not only higher
density during the summer season but also consisted
of more diverse fauna. Infaunal macrobenthos
was
observed that the estuary harbored larger number of
organisms and more specifically the gastropods
Cerethedia
spp. were incomparability in all the seasons.
Low benthic production, especially polychaetes, during
monsoon could be due to the low temperature and
salinity prevailing in that area. The decrease of
benthic in monsoon may be attributable to the low
temperature and salinity. A medium amount of organic
carbon and salinity supports more benthic production.
So, it can be deduced from the study that ecological
factors like temperature, salinity and dissolved oxygen
have great influence on the abundance and distribution
of infaunal macrofauna in Vellar estuary.
Mangrove forests are among the most productive
ecosystems worldwide (
Kathiresan et al. 1996
). They
enrich coastal waters, yield commercial forest
products, protect coastlines and support coastal
fisheries. However, mangroves exist under conditions
of high salinity, extreme tides, strong winds, high
temperatures and muddy, anaerobic soils (Kathiresan
and Bingham 2001). Especially mangrove environment
of the present study (transect II) showed the maximum
number of individuals and species richness than in the
other transects. It clearly showed the enrichment of
food materials and organic load in this transect. It was
comparatively low with the earlier studies of this
estuary, while the highest number of organisms and
number of species recorded in transect I (estuarine
mouth).
After mangrove vegetation in this estuary, species
diversity and species richness were found to be higher
compared to the previous investigations. An important
finding of the present study is record of gastropod
C.
cingulata
in higher abundance than the other species
of macrobenthos after mangrove plantation. This
gastropod has not been recorded in Vellar estuary by
Ajmal Khan et al. (1975) and Chandran et al. (1982)
before mangrove plantation. Small number of
C.
cingulata
has been reported by Fernando (1987), and
its abundance increased after mangrove plantation
(Murugasan et al., 2007).
Kathiresan et al. (1996) and
Kathiresan (2000) have reported high density of
C.
cingulata
in a permanent natural mangrove
environment (Pichavaram mangrove forest, Tamil
Nadu, India) near to the Vellar estuary. In this
consequence, gastropod
C. cingulata
might be migrating
from the adjacent natural mangrove environment into
this estuary after artificial mangrove plantation.
Author’s contribution
AH carried out the sampling, samples processing up to species
level, data management and draft the manuscript. KGMTA
participated in sample collection, data interpretation, statistical
analysis and final draft the manuscript. RR was involved in the
design of work and editing of the manuscript. OJF was
involved an idea of this investigation, and revision of the
manuscript for appropriate to publication.
Acknowledgments
Authors are thankful to higher authorities of CAS in Marine
Biology, Annamalai University, Parangipettai for providing
with facilities and support.
References
Abbott R.T., and Dance S.P., 1982, Compendium of Sea Shells, A Color
guide to more than 4,200 of the world’s Marine Shells, E.P. Dutton Inc.,
New York, pp.411
Achuthankutty C.T., 1976, Ecology of sandy beach of sancole, Goa. Part 1:
Physical factors influencing production of macro fauna
,
Indian Journal
of Marine Science, 5(1): 91-97
Ajmal Khan S., Vivekanandan E., and Balasubrahmanyan K., 1975, Bottom
fauna in two regions of the Vellar estuary, In: Natarajan, R. (ed.),
Recent Researches in Estuarine Biology Hindustan publishing
Corporation, Delhi, pp 255-272
Ajmal Khan S., Murugasan P., Lyla P.S., and Jaganathan S., 2004, A new
indicator macro invertebrate of pollution and utility of graphical tools
and diversity indices in pollution monitoring studies. Current Science,
87(11): 1508-1510