ABSTRACT
A qualitative study on species composition and diversity of phytoplankton flora was carried out in the Anjanapura reservoir. Water samples were collected monthly at four sites from November 2005 to October 2007 for plankton analysis. A total of 152 phytoplankton species belonging to 59 genera were recorded. The species belonging to genera Crucigenia, Pediastrum, Scenedesmus, Tetraedron, Cyclotella, Gyrosigma, Melosira, Navicula, Fragillaria, pinnularia, Synedra, Closterium, Cosmarium, Euastrum, Staurastrum, Gleocapsa, Merismopedia, Microcystis,Oscillatoria, Euglena and Phacus were found dominant. Phytoplankton density was recorded in the range of 222-1467 Org l-1 for chlorococcales, 267-1467 Org l-1 for diatoms, 44-889 Org l-1 for desmids, 44-889 Org l-1 for blue-greens and 22-1667 Org l-1 for euglenoids. Seasonal density Shannon-Weiner diversity index (1.60-1.88) indicate that reservoir exhibited rich phytoplankton and Nygaard tropic status indices for myxophycean(1.0-1.50), chlorophycean(1.62-2.16), diatoms(0.10-0.14), euglenophycean(0.18-0.19) and compound quotient(3.25-4.66) showed that reservoir was moderately polluted. From the observed data, it could be concluded that the presence of more diverse group of phytoplankton indicate the productivity of the reservoir.
ABSTRACT
An investigation was carried out during June 2005 to May 2007 on hydrography, composition and community structure of phytoplankton including chlorophyll a in Parangipettai coastal waters (southeast coast of India). Air and surface water temperatures varied from 25.5 to 31.2 °C and from 25 to 29.3°C, respectively. Salinity values varied from 5 to 33.1‰ and the pH ranged between 7.2 and 8.3. Dissolved oxygen content varied from 3.1 to 7.9 mg l-1 while the light extinction coefficient values (LEC) ranged between 1.8 and 11.0 cm. The range of inorganic nutrients viz., nitrate, nitrite, phosphate and silicate were: 6.5 - 27.0 µM; 1.0 - 8.9 µM; 0.1 - 3.0 µM and 15.0 - 140 µM, respectively. The range of chlorophyll a was: 2.0 - 7.5 µg l-1. Presently, 117 phytoplankton species representing different classes viz: Bacillariophyceae (66); Dinophyceae (22); Cyanophyceae (19); Chlorophyceae (7) and Chrysophyceae (3) were recorded. The phytoplankton cell abundance varied from 0.14 to 132 cells ml-1, with peak diversity (3.52 bits ind.-1) during summer season. The maximum abundance was found during summer season coinciding with the stable hydrographical conditions. Canonical Correspondence Analysis was applied in this study for discriminating environmental factors effecting on phytoplankton community at species level.