MICRO ALGAL DIVERSITY OF THE FRESH WATER LAKE IN THIRUVANANTHAPURAM DISTRICT, KERALA
|Priya Gopinath. Ta* and Ajit Kumar. K.Ga.
|Corresponding Author: E-mail: [email protected]|
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Vellayani Lake is the largest fresh water lake in Thiruvananthapuram district of Kerala. The lake water is extensively used for drinking and irrigational purposes. The lake is under the threat of pollution, encroachment and sand mining. The present study is aimed to record the algal diversity in 8 sites of Vellayani Lake during the pre-monsoon and monsoon period of 2013. Phytoplanktons were collected using plankton net and direct mass collection was employed for larger ones. The specimens were preserved at the site itself and brought to the laboratory and observed under Research microscope. The algal genera were identified referring various monographs. Forty two phytoplankton genera have been reported during the study period. The phytoplankton showed abundance in the pre- monsoon and had low density during the monsoon. The diversity index for the 5 families of phytoplankton during the pre-monsoon and monsoon period was also calculated. Chlorophyceae showed a diversity index of 2.71, Bacillariophyceae 2.82, Cyanophyceae, Euglenophyceae and Chrysophyceae with an index value of 1.7, 1.9, 1.07 respectively The degree of abundance of phytoplankton in the decreasing order is Bacillariophyceae, Chlorophyceae, Cyanophyceae and Euglenophyceae, chrysophyceae and the pollution indicator phytoplankton like Closterium, Nitzschia, and Oscillatoria were found in the lake and hence these sites are in the verge of pollution. So these areas of the lake need special attention for preventing further degradation.