Seasonal influence of physicochemical and climatic parameters on phytoplankton diversity and abundance pattern in community managed semi-impacted floodplain wetland.

Wetlands provide numerous ecological services and are key habitats for aquatic flora and fauna. In the Beledanga wetland, the current study was conducted for 3 years, from July 2019 to June 2021, to evaluate the seasonal influence of physicochemical parameters on phytoplankton diversity and abundance patterns. Overall 48 genera of phytoplankton were observed. Bacillariophyceae (27%) contributed the maximum to the total phytoplankton density. The total abundance of phytoplankton was found utmost during monsoon (4.081 × 10³ unit l⁻¹) and least during post-monsoon (3.316 × 10³ unit l⁻¹). One-way analysis of variance indicated significant seasonal differences (p < 0.05) for some genera. The study gave the idea about the most influencing physic-chemical parameters (dissolved oxygen, turbidity, total hardness, Ca²⁺, and total nitrogen) on the growth of phytoplankton with the help of different multivariate and univariate analysis (canonical correspondence analysis and Karl Pearson's correlation). The study again highlighted that climate parameters (temperature and rainfall) had some effect on the phytoplanktonic groups. Our study conceded that N:P in the studied wetland was less than the Redfield ratio (16:1) in all three seasons, while the Si:P ratio was noticed in the high range (15:1) during pre-monsoon. The value of the Shannon diversity index and Margalef's species richness index were noticed to be > 3, which signified quite rich in phytoplankton diversity. But the value of Algal Pollution Index, which describes the ecological pollution level based on the present algal genera was observed high throughout all seasons, indicating organic load. So in future the studied wetland may get adversely affected with influence of anthropogenic activities. Therefore, for sustainable biodiversity of the waterbody, the anthropogenic activities (retting and intensification of agricultural farming) and macrophytes need to be controlled and regulated. [ABSTRACT FROM AUTHOR]