PLANKTON COMMUNITY AND THEIR INTER RPLANKTON COMMUNITY AND THEIR INTER RELATIONSHIP WITH PRIMARY PRODUCTIVITY OF KAPTAI LAKEELATIONSHIP WITH PRIMARY PRODUCTIVITY OF KAPTAI LAKE

Abstract

The purpose of the study was to identify the plankton communities and establish a relationship between plankton abundance and primary productivity in Kaptai Lake from March to August, 2022. Sampling was done by monthly frequency. A total of 15 genera of phytoplankton were identified under the classes Chlorophyceae, Cyanophyceae, Dinophyceae and Euglenophyceae from Kaptai Lake; among which Chlorophyceae was the dominant class. Identified phytoplankton genera were Actinastrum, Cosmarium, Chlamydomonus, Mougeotia, Pandorina, Pediastrum, Spirogyra, Staurastrum, Xanthidium, Zygnema, Anabaena, Aphanothece, Gleocapsa, Ceratium and Phacus. The highest total phytoplankton abundance in Kaptai Lake was recorded in March at Shubholong Bazar station which was 26.7×103 cells/L whereas the lowest value was observed in July at Jolojan Ghaat station which was 8.96×103 cells/L. A total of 8 genera of zooplankton were identified under the groups Rotifera, Crustacea, Arthropoda and Protozoa; among which, Rotifera was the dominant group. Identified zooplankton genera were Brachionus, Euchlanis, Keratella, Polyarthra, Asplanchna, Nauplius, Cyclops and Paramecium. The highest total zooplankton abundance in Kaptai Lake was recorded to be (5.37×103 cells/L) in the month of April at Shubholong Jhorna station whereas the lowest value (1.92×103 cell/L) was observed in July at Jolojan Ghaat station. The mean gross primary productivity of Kaptai Lake throughout the period of study was 262.08±23.66) mgC/m3 /day and net primary productivity was (155.11±23.59) mgC/m3 /day. Phytoplankton abundance showed a statistically significant, strong positive correlation with zooplankton abundance; as well as a moderate positive correlation with gross primary productivity (p < 0.05).