ZOOPLANKTON DIVERSITY AND THEIR SEASONAL VARIATION IN THE RIVER CHANGA, WEST BENGAL, INDIA

River changa originates from the Himalaya and it is a tributary of the river Mahananda. Purpose of the study is to investigate the diversity and seasonal variation of zooplankton. A survey was carried out for two years at four sampling sites of the river Changa. Ten litre of water was filtered with the help of plankton net (75µm) and filtrated water then preserved in 4% formalin and then concentrate by centrifugation for 10 minute at 1000 RPM. A total of 20 zooplankton belonging to protozoa, Rotifera, Cladocera and Copepoda with 5 species each groups were recorded in the river Changa. Range and mean value of taxa, individuals, Shanon diversity index, Margalef’s richness index, dominance index and evenness index were reported 11.31(6-16), 17.81 (6-35), 2.34 (1.79-2.71), 3.65 (2.60-4.78), 0.0035 (0.0701-0.1667) and 0.0016 (0.9457-1) respectively. Taxa, number of individuals, Shanon diversity index were maximum in winter and minimum in Monsoon at every site. Moderate number of zooplankton genera was reported from the rivers Changa. Presence of Rotifera indicates organic pollution of the river water.