Plankton Diversity of Bornadi River Basin with Special Reference to Indo-Bhutan Landscape, BTR, Assam, India

The present study was conducted to assess the plankton diversity of the Bornadi River Basin with special reference to the Indo-Bhutan Landscape, Bodoland Territorial Region (BTR), Assam, India. A total of 50 genera of planktons were found, out of which the phytoplankton populations comprised 31 genera while the zooplankton populations comprised 19 genera. The study revealed that the relative abundance of phytoplankton was predominated by Chlorophyta representing the highest proportion (65.9%), followed by Cyanophyta (17.4%) and Bacillariophyta (16.7%). Chlorophyta remained dominant seasonally (64.1–69.7%) and spatially (62.8–69.1%). The relative abundance of zooplankton was dominated by Copepoda representing the highest proportion (35.6%), followed by Rotifera (33.4%), Protozoa (19%), and Cladocera (11.9%). Brachionus sp. showed the highest abundance during pre-monsoon and monsoon, Cyclops sp. during retreating monsoon and winter. Site-specific abundance revealed that Cyclops sp. was most dominant in all sites. The study also revealed that seasonal variations significantly influenced the diversity, abundance, and community structure of zooplankton and phytoplankton, with the monsoon enhancing zooplankton diversity and winter encouraging phytoplankton proliferation.