Zooplankton diversity of a sub-tropical reservoir of Mizoram, Northeast India

This study on zooplankton diversity from the state of Mizoram of northeast India, based on plankton samples collected from Khawiva reservoir during November 2005-October 2007, recorded a total of 46 species. Zooplankton indicated monthly richness ranging between 19-36 and 25-34 species; registered 52.8-88.9 and 60.0-89.3% community similarities (vide Sørensen’s index); and comprised between 31.2±12.7 and 46.7±11.3% of net plankton abundance during two years, respectively. Copepoda and Rotifera, together, influenced zooplankton abundance. Rhizopoda and Cladocera showed limited importance while Nematoda and Ciliata recorded poor densities. Mesocyclops spp. > Keratella tropica are important taxa. Our results are characterized by moderate species diversity, high evenness and low dominance except in some months. Richness, abundance and species diversity followed no definite patterns of monthly variations. Individual abiotic parameters exerted limited influence on zooplankton richness and abundance, and on abundance of its constituent groups. The canonical correspondence analysis with fifteen abiotic parameters explained high cumulative variance (84.8%) of zooplankton assemblages along axis 1 and 2 with importance of water temperature, rainfall, free carbon dioxide, conductivity and phosphate. Sladecek’s Q B/T quotient and Shannon’s diversity index reflected mesotrophic nature of Khawiva reservoir.