RESUMEN
A seasonal study was undertaken to understand the influence of wastewater on phytoplankton distribution in a water body of East Kolkata Wetland (EKW), a designated Ramsar site in Kolkata, West Bengal, India. A total of 19 different genera of phytoplankton belonging to 5 phyla were recorded. Among all the groups, Chlorophyceae was found to be dominated by 8 genera followed by Bacillariophycaeae (4 genera), Cyanophyceae (4 genera), Euglenophyceae (2 genera), and Zygnematophyceae (1 genus). Seasonal variability showed maximum dominance of phytoplankton during post-monsoon and least during pre-monsoon months. Shannon-Wiener diversity (H') indices indicated Bacillariophyceae to be most species rich (1.059) while the most dominant group (D) was observed to be Chlorophyceae (0.507). Assessment of Palmer algal pollution index (PI) revealed the water body is impacted by high organic pollution during monsoon (22) compared to the pre-monsoon (19) and post-monsoon seasons (15). The results of canonical correspondence analysis (CCA) indicated water temperature, alkalinity, total dissolved solids, dissolved oxygen, and electrical conductivity as the major influencing parameters for growth and distribution of the phytoplankton in the water body. Therefore, it can be stated that hydrological alteration of a water body fed with wastewater plays a significant role in regulating the plankton density, richness, and diversity.