The Spatio-temporal Variations of Phytoplankton Diversity of a Subtropical Sacred Lake of Meghalaya State, Northeast India

The spatio-temporal variations of phytoplankton diversity of the ‘de-mineralized’ sacred Thadlaskein Lake of Meghalaya state of northeast India are monitored based on analyses of the littoral and limnetic assemblages. Our study reveals a total of 51 species, depicts notable desmid diversity, and records the speciose constellation of 49 species per sample. Phytoplankton indicates importance vis-a-vis net plankton abundance and exhibits quantitative dominance of Charophyta; Chlorophyta > Bacillariophyta > Dinozoa > Chrysophyta are sub-dominant groups, and Cyanobacteria and Euglenozoa record poor densities. Closterium spp., Cosmarium spp., Scenedesmus spp. and Staurastrum spp. are noteworthy taxa, and eleven species contribute notably to phytoplankton abundance. Our results depict high species diversity, lower dominance and high evenness. Individual abiotic factors exert the differential spatial influence on phytoplankton, and register the relative importance of the rainfall, transparency and total hardness, while the CCA registers the moderate cumulative influence of 10 abiotic factors on the littoral and limnetic assemblages. The spatial variations of various aspects of phytoplankton diversity and the influence of abiotic factors are hypothesized to the habitat heterogeneity amongst the two regions. The present study is a useful contribution to the phytoplankton diversity of India and that of the subtropical lacustrine environs of the country.