Zooplankton diversity and seasonal variations in Thandava reservoir, Visakhapatnam, India

Zooplankton diversity and seasonal variations were studied at three stations of Thandava reservoir to provide new insights into reservoir ecology and water quality. The study was carried out during the study period from Nov 2015 to Oct 2016. A total number of forty four zooplanktons both micro and macro species were identified in this reservoir at three stations. Among eight zooplankton groups, the diversity of rotifera comprise of 17 species (24.38%), cladocera 8 (17.63%), copepoda 5 (17.08%), ostracoda 2 (14.63 %), protozoa 3 (12.03%), crustacea 7 (11.18%), fish larvae and eggs 2 (03.08%). The number and percentage of zooplankton monthly population was highest 9.96% in during May 2016 and lowest 7.11% in November 2016. The group wise and season wise zooplankton mean diversity index was analysed and calculated, rotifera were highest (37.14%) in summer lowest (26.46%) in winter. Followed by cladoceran were highest (36.96%) and lowest (30.01%) in monsoon, followed by copepoda highest (39.40%) and lowest (28.61%), ostracoda highest (35.93%) and lowest (34.26%) in monsoon periods. Protozoa highest (41.80%) and lowest (27.77%), crustacea highest (41.01%) in monsoon and lowest (21.47%) in summer and Fish larvae and eggs highest (57.91%) in monsoon and lowest (16.02%) in summer. Shannon-Wiener index and Margalef’s richness index (R1) results were calculated for zooplankton diversity in this reservoir.