Influence of Water Quality on Composition and Seasonal Abundance of Phytoplankton Community in Thol Wetland, Gujarat, India

The study deals with water quality parameters affecting the composition, seasonal abundance and dominance of phytoplankton in a wetland, Thol Bird Sanctuary, Central Gujarat, India. Hydrochemical parameters of water samples were analysed during September 2007 to August 2009. Monthly variation of water quality parameters like temperature, pH, dissolved oxygen, total dissolved solids, total alkalinity, total hardness, chloride, phosphate, sulphate and nitrate were investigated during the study period. Nutrients like chloride, phosphate, sulphate and nitrate were found higher during summer and lower during monsoon months in both the years. 102 phytoplankton taxa were identified of which Cyanophyta represented by 44 species, constituted the largest group, followed by Bacillariophyta by 25 species, Chlorophyta by 23 species and Euglenophyta by 10 species. Remarkable seasonal variation in mean density of Chlorophyta and Bacillariophyta was observed during the study period. Chlorophyta members were present in reasonable numbers throughout the study period, being most abundant in post monsoon and winters. Cyanophyta and Euglenophyta populations showed less seasonal variations except a noticeable increased in density of Euglenophyta in summer 2009. The interrelationship between the hydrochemical properties and phytoplankton assemblages and influence of water quality parameters were investigated by adopting statistical correlation coefficient analysis and linear curves. The hierarchical cluster analysis was used to define biologically distinct regions within the wetland based on the composition of phytoplankton.