Seasonal Variation of Water Quality Parameters and Their Impact on Fish Biodiversity Indices of Hasadanga Beel: A Case Study

Abstract

Fish diversity indices and their correlation with seasonal fluctuation of physicochemical parameters of Hasadanga beel was aimed to be studied. A three-year study on the relationship between the seasonal fluctuation of water quality parameters and fish biodiversity indices was conducted in Hasadanga Beel, a floodplain lake of Nadia district, West Bengal to measure the ecological health of the lake. Samples of water and fish species were collected at pre-monsoon, monsoon and post-monsoon period from 2015-2017 to estimate physicochemical parameters of water and fish biodiversity indices i.e. Shannon-Weaver species diversity index, Margalef’s Species richness index, Pielou’s Species evenness index and Simpson’s index of dominance. Total of 34 different fish species belonging to 8 Orders were found during the study period which varies seasonally. Water temperature (20.0-31.4 °C), pH (7.70-8.75), dissolved oxygen (3.9-5.0 mg/l), Free CO2 (0.0-15.0 mg/l), total alkalinity (156-193 mg/l), hardness (113-145 mg/l), and BOD (1.03-1.94 mg/l) values varied significantly (p<0.05) between three seasons. Shannon-Weaver species diversity index (Hꞌ) is ranged between 1.2911-1.3502, Margalef’s species richness index (D) is measured between 12.72-14.15, Pielou’s species evenness index (Jꞌ) is recorded between 0.8829-0.9140 and Simpson’s index of dominance (ID) is ranged between 0.05346-0.07139. Hꞌ has positive correlation with pH, alkalinity and hardness whereas negative correlation with temperature, free CO2, DO and BOD. D has positive correlation with pH, free CO2, DO and hardness whereas negative correlation with temperature, alkalinity and BOD. Jꞌ has positive correlation with temperature, pH, alkalinity and hardness and whereas negative correlation with free CO2, DO and BOD. ID has positive correlation with temperature, free CO2, DO and BOD whereas negative correlation with pH, alkalinity and hardness. The obtained result suggests that various water quality parameters specially temperature, dissolved oxygen and pH are the key factors to regulate the fish biodiversity indices and should be taken into consideration for making policies for sustainable use of floodplain lakes.