Seasonal variations of phytoplankton diversity in the Coleroon coastal waters, southeast coast of India
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Seasonal variations of phytoplankton diversity in the Coleroon coastal waters, southeast coast of India Thillai Rajasekar K1 , Rajkumar M1,2 , SUN Jun2∗ , Ashok Prabu V1 , Perumal P1,3 1 2 3
Centre of Advanced Study in Marine Biology, Annamalai University, Tamil Nadu, India Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China Department of Biotechnology, Periyar University, Tamil Nadu, India
Received 15 July 2009; accepted 11 February 2010 ©The Chinese Society of Oceanography and Springer-Verlag Berlin Heidelberg 2010
Abstract The results of an investigation carried out during June 2005 to May 2007 on physico-chemical parameters, species composition and community structure of phytoplankton including Chlorophyll a (Chl-a) at the Coleroon coastal waters (Southeast coast of India) are reported. Air and surface water temperatures (◦ C) varied from 25.1 to 30.1 and from 24.5 to 28.5 respectively. Salinity values varied from 6 to 28.5 and the pH ranged between 7.0 and 8.3. Variation in dissolved oxygen content was from 3.1 to 7.5 mg/dm3 while the light extinction coefficient values (LEC) ranged between 3.1 and 10.1 cm. The ranges of inorganic nutrients (µmol/dm3 ) viz., nitrate, nitrite, phosphate and silicate were 10.1–23.4, 1.2–8.9, 0.2–3.1 and 55–125, respectively. The ranges of Chlorophyll a (µg/dm3 ) values was 2.0–7.5. Presently, 124 phytoplankton species representing different classes viz: Bacillariophyceae (77), Dinophyceae (19), Cyanophyceae (15), Chlorophyceae (10) and Chrysophyceae (3) were recorded. The phytoplankton cell abundance varied from 0.290 to 111.662 cells/cm3 , with peak diversity (3.38 bits/ind.) during summer season. The maximum abundance was found during summer season coinciding with the stable hydrographical conditions. The seasonal distribution and abundance of phytoplankton are discussed in relation to hydrographical parameters. Canonical Correspondence Analysis (CCA) was applied in this paper for discriminating environmental factors having effect on phytoplankton community at species level. Coleroon coastal water is subjected to long term fluctuations in physico-chemical parameters depending upon the seasonal tidal amplitude and freshwater influx resulting in a continuous exchange of organic, inorganic, plant and animal matters. Key words: physico-chemical parameters, phytoplankton, species composition, abundance, diversity, Coleroon coastal waters
1 Introduction Estuaries are economically important ecosystems for fisheries in tropical regions (Kawabata et al., 1993) and they act as a transitional zone between land and sea (Bardarudeen et al., 1996). Phytoplankton initiates the marine food chain, by serving as food to primary consumers like zooplankton, shellfish and finfish (Saravanakumar et al., 2008; Mathivanan et al., 2007; Tas and Gonulol, 2007; Sridhar et al., 2006; Zhang et al., 2005). Biomass and productivity of phytoplankton in different size ranges are important factors regulating the productivity of higher tropic-level organisms. The pelagic algal communities make
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