Phytoplankton communities of two floodplain lakes of the Dibru Saikhowa biosphere reserve, Tinsukia, Assam (Northeast India): Ecology, richness, and abundance

Phytoplankton communities of Dibru Saikhowa Biosphere Reserve (DSBR) beels were studied from October 2013 to September 2015 in two floodplain lakes (beels), namely Maghuri beel and No.11 beel in Tinsukia district, upper Assam, Northeast India. Phytoplankton reveal a richness of (61 species) belonging to five groups: Chlorophyta (35 species) > Bacillariophyta (13 species) > Euglenophyta (7 species) > Cyanophyta (5 species) > Dinophyta (1). The monthly phytoplankton richness indicated 13–32 (25 ±6) species) and 21–39 (30 ±5) and with distinct species importance of Chlorophyta (5-17) 12 ±4 and (10-24) 15 ±3 species in Maghuri beel and No.11 beel respectively. Phytoplankton abundance ranged between 162 ±157 n/L and 138 ±39 n/L and comprised a sub-dominant component of net plankton, i.e., between 39.7 ±15.8% and 41.0 ±9.9% in Maghuri beel and No.11 beel respectively. Seventeen abiotic factors recorded relatively limited influence on the phytoplankton richness and abundance of the sampled bells. The canonical correspondence analysis asserted higher cumulative influence along the first two axes of 17 abiotic factors on phytoplankton assemblages of Maghuri beel (76.46%) than in No.11 beel (61.73%) beels.