Diversity of Phytoplankton of a sub-tropical reservoir of Mizoram, northeast India

Phytoplankton of Khawiva reservoir of Mizoram, northeast India (NEI) revealed a total of 55 species; nearly concurrent mean monthly richness and high community similarities (vide Sørensen index) during two years affirmed homogeneity in its species composition. Phytoplankton comprised dominant component (61.1±14.3%) of net plankton and recorded wider density variations. Chlorophyta influenced phytoplankton abundance with quantitative importance of Staurastrum spp. >Xanthidium spp. >Cosmarium spp. in particular. Bacillariophyta formed subdominant group; Cryptophyta and Cyanophyta showed limited importance; and Euglenophyta and Dinophyta recorded poor densities. Phytoplankton is characterized by moderate species diversity, high evenness and low dominance but with wide variations. Richness, abundance and species diversity followed no definite patterns of monthly variations during two years. Insignificant influence of individual abiotic factors on phytoplankton assemblages coupled with low cumulative influence of fifteen abiotic parameters (vide CCA) yielded little insight on overall role of abiotic parameters.