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International Journal of Marine Science 2013, Vol.3, No.2, 4
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http://ijms.sophiapublisher.com
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Research Report Open Access
Influences of Environmental Factors on Fish Assemblage in the Tropical
Estuary of South West Coast of India, A Case Study of Kodungallur-
Azhikode Estuary
P.R. Jayachandran , S. Bijoy Nandan , O.K. Sreedevi , V.F. Sanu
Department of Marine Biology, Microbiology & Biochemistry, School of Marine Sciences, Cochin University of Science and Technology, Fine Arts Avenue,
Kochi-682016, Kerala, India
Corresponding author email: jayachandran2701@gmail.com;
Authors
International Journal of Marine Science, 2013, Vol.3, No.2 doi: 10.5376/ijms.2013.03.0002
Received: 20 Nov., 2012
Accepted: 21 Dec., 2012
Published: 26 Dec., 2012
Copyright:
©
2013 Jayachandran et al., This is an open access article published under the terms of the Creative Commons Attribution License, which permits
unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Preferred citation for this article:
Jayachandran et al., 2013, Influences of Environmental Factors on Fish Assemblage in the Tropical Estuary of South West Coast of India, A Case Study of
Kodungallur-Azhikode Estuary, International Journal of Marine Science, Vol.3, No.2 4
-
16 (doi: 10.5376/ijms. 2013.03.0002)
Abstract
A proper monitoring of aquatic environment is crucial to appropriate management of the fisheries that rely on harvests from
the environment and attempts of present study have been made to demonstrate links with environmental variability and fish abundance
in the Kodungallur-Azhikode estuary (KAE). Annual average fish production in the estuary was declined considerably to 908.6 tons
during 2009-2010, where 2 747 tons was reported. Sixty three species of fin fishes, six species of penaeid shrimps, one species of
Palaemonid prawns, two species of crabs, four species of bivalves and two species of edible oysters were observed in this study. Present
study revealed that, Salinity is consistently the most important parameter explaining variation in assemblage composition and
abundance of KAE; the availability of fish for recruitment into an estuary depends primarily upon the distributional range of euryhaline
marine and estuarine species. The direct gradient analysis, first CCA axis, which explained most of the variation (45%) in the species
data, was related to salinity, transparency and pH, and first two CCA axes together explained 72% of the cumulative percent variance of
species-environment relationship. The importance of monitoring the estuarine condition in relation to fish assemblage was discussed,
with significance on the potential use of estuarine fish assemblages and their monitoring and surveillance in management programs.
Keywords
Kodungallur-Azhikode estuary; Fish productivity; Water quality; Eutrophication
1 Introduction
The structure and function of estuarine ecosystems are
sustained by synergistic feedbacks between organisms
and their environment. While many investigations
aimed at detecting environmental and ecological
changes within estuaries had focused primarily on
water quality and the associated biota, there are
relatively few studies based exclusively on fishes
(Whitfield and Elliott, 2002). Several investigators
had suggested that biotic processes, such as
competition and predation, might be influential in
controlling the spatial and temporal patterns of
occurrence of fish in estuaries. In addition, a various
abiotic factors have been associated with the structure
of fish assemblages including salinity, temperature,
turbidity, dissolved oxygen, freshwater inflow,
structural attributes of habitat, depth, and hydrography
(Martino and Able, 2003).
Worldwide, nitrogen loadings resulting from human
activities, as well as the number of estuaries and coastal
seas reporting low dissolved oxygen concentrations
had dramatically increased since the 1950s (Diaz, 2001;
Boesch, 2002; Seitzinger et al., 2002; Diaz and
Rosenberg, 1995). In many of the estuaries, illegal
fishing had contributed to declining abundances of
species that spend all or part of their life cycle in
estuaries (Secor and Waldman, 1999; Lotze et al., 2006)
and this recruitment of fishes from estuaries were
strongly drive marine population dynamics (Elliott and
Taylor, 1989). It was believed that large-scale patterns
in the distribution of organisms result primarily from
species responses to their physical environment,
because dominant abiotic variables were thought to
act like physiological sieve, thereby playing a vital
role in the structuring of a community. Abiotic factors
may set up the community framework, while biotic
interactions refine species distribution patterns within
this structure. However, much research on fish