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

Abstract

Wetlands provide numerous ecological services and are key habitats for aquatic flora and fauna. In the Beledanga wetland, the current study was conducted for three years, from July 2019 to June 2021, to evaluate the seasonal influence of physico-chemical parameters on phytoplankton diversity and abundance patterns. Overall 48 phytoplankton taxa were observed. Group 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 ANOVA indicated significant seasonal differences (p<0.05) for some genera. The study gave the idea about the most influencing physic-chemical parameters (DO, turbidity, total hardness, Ca2+, and nitrate) on the growth of phytoplankton with the help of different multivariate and univariate analysis (Canonical correspondence analysis, 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 theShannon diversity index and Margalef’s species richness index were noticed to be > 3, which signified quite rich in phytoplankton diversity and less pollution in the ecosystem. The algal pollution index was predominant during all the seasons, indicating a high organic load which might be due to seasonal jute retting and intensification of agricultural farming.