Abstract:

This study monitors the spatio-temporal variations of phytoplankton of a soft-water and de-mineralized reservoir of Meghalaya state of northeast India. Phytoplankton assemblages of the littoral and limnetic regions reveal total 36 species and diverse desmids, and contribute dominantly to net plankton abundance. Our results record the quantitative importance of Charophyta > Bacillariophyta > Dinophyta and Charophyta > Dinophyta, and the ‘specialist’ nature of 11 and six species at the littoral and limnetic regions, respectively. Staurastrum spp. and Cosmarium spp. are notable taxa. Phytoplankton indicates moderate species diversity and depicts dominance and evenness variations. The individual abiotic factors exert differential influence on various taxa at the two regions and the canonical correspondence analysis registers 73.02 and 71.14% cumulative influence of 10 abiotic factors on the littoral and limnetic assemblages, respectively. The spatial differences of phytoplankton composition, richness, abundance, important groups and taxa, specialist species, diversity indices and the influence of individual abiotic factors are hypothesised to habitat heterogeneity amongst the sampled regions. This study records notable temporal differences of phytoplankton richness, abundance, diversity and the role of abiotic factors vis-a-vis the limited survey of November 1990–October 1991. 

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