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Bloom forming species of phytoplankton in two coastal waters in the Southeast coast of India |
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| Authors: | K Thillai Rajasekar M Rajkumar Jun Sun V Ashok Prabu P Perumal |
| Institution: | 1. Centre of Advanced Study in Marine Biology,Annamalai University,Parangipettai-608502,Tamil Nadu,India 2. Centre of Advanced Study in Marine Biology,Annamalai University,Parangipettai-608502,Tamil Nadu,India;Institute of Oceanology,Chinese Academy of Sciences,Qingdao 266071,P.R. China 3. Institute of Oceanology,Chinese Academy of Sciences,Qingdao 266071,P.R. China 4. Centre of Advanced Study in Marine Biology,Annamalai University,Parangipettai-608502,Tamil Nadu,India;Department of Biotechnology,Periyar University,Salem-636011,Tamil Nadu,India |
| Abstract: | The results of an investigation carried out during June 2005 to May 2007 on bloom-forming phytoplankton species composition and abundance in the Parangipettai and Coleroon coastal waters(Southeast coast of India)are reported. Air and surface water temperatures(℃)varied from 25. 1 to 30. 1 and 24. 5 to 28. 5, respectively, in the former waters and from 25. 5 to 31.2 and 25. 0to 29. 3 in the latter waters. The respective salinities varied from 6. 0 to 28. 5 and 5. 0 to 33. 1 and the respective pH ranged between 7. 0and 8. 3 and 7. 2 and 8. 3. Correspondingly, the dissolved oxygen content varied from 3. 1 to 7. 5 and 3. 1 to 7. 9 mgL-1 while the light extinction coefficient(LEC)values ranged between 3. 1 and 10. 1 and 1.8 and 11.0. The content ranges of inorganic nutrients, I. E. , nitrate, nitrite, phosphate and silicate(μmolL-1), in the Parangipettai and Coleroon coastal waters were: 6. 5-27. 0; 1.0-8. 9; 0. 1-3. 0and 15. 0-140 and 10. 1-23. 4; 1.2-8. 9; 0. 2-3. 1 and 55-125 respectively. The chlorophyll a contents in both waters ranged from2. 0-7. 5 μgL-1.Presently, 124 phytoplankton species representing different classes were recorded in the Coleroon coast, viz, Bacillariophyceae(77); Dinophyceae(19); Cyanophyceae(15); Chlorophyceae(10)and Chrysophyceae(3), whereas 117 phytoplankton species were recorded in the Parangipettai coast, viz, Bacillariophyceae(66); Dinophyceae(22); Cyanophyceae(19); Chlorophyceae(7)and Chrysophyceae(3). The phytoplankton cell abundance in the Parangipettai and Coleroon coastal waters varied from 290 to111662 and 140 to 132 757 cells L-1, respectively, with peak diversity(3. 38 and 3. 52 bits ind-1.)recorded in summer. The maximum abundance occurred in summer coinciding with the stable hydrographical conditions. The seasonal distribution and abundance of phytoplankton are discussed in relation to hydrographical parameters. Totally 31 and 24 species of phytoplankton were found to be bloom-forming in the Parangipettai and Coleroon coastal waters, respectively. Presently Trichodesmium bloom was also observed, which appeared at the 10 fathom level of the coastal water and quickly spread to the marine zone of the Vellar estuary and near the mouth region of the mangrove waters. The Parangipettai and Coleroon coastal waters are subject to long term fluctuations in physico-chemical conditions depending upon the seasonal tidal range and freshwater influx, resulting in a continuous exchange of organic, inorganic, plant and animal matters. |
| Keywords: | Bloom-forming phytoplankton species abundance Parangipettai and Coleroon coastal waters |
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