In the present study, an attempt has been made to investigate the seasonal and temporal change in the quality of water and to find out better utilisation of present lentic system. Water Quality Index (WQI) and productivity of a pond ecosystem have been determined. The Water quality Index (WQI) facilitates to evaluate surface water quality for protection of aquatic life with specific guidelines. Water quality was investigated for four months (from January, February, March and April of 2015). The index calculated in this work is composed of nine parameters which are significant for aquatic life. Water quality index were observed to be 483, 478, 469, and 487 during January, February, March, and April respectively. Water quality was found as poor for the aquatic life based on the water quality index. Total phosphate (TP) was observed to be 9.3 mg/l, 13.7 mg/l, 9.5 mg/l and 14.3 mg/l, during the month of January, February, March, and April, respectively classifying the water as high-strength w.r.t. phosphate. Chlorophyll a was found to be 17.9 µg/ml, 20.9 µg/ml, 13.3 µg/ and 32.8 µg/ml during the four samplings. The productivity (as gross primary productivity) was observed as 245 mgO2/l/hr. High value of the TP, Chla, and GPP indicate that water body was hypereutrophic. Despite being hypereutrophic water body, no algal bloom was observed. Apart from it, temporal variation for Chlorophyll a was observed. During spring (March) the concentration was minimum because of the high growth of Ceriodaphnia Spp. and maximum in summer due to high intra-species competition, and stress due to high temperature. High concentration of total suspended solid (TSS) was also one of the reason leading to supress the growth of phytoplanktons/algae. During the study period, thermal stratification was also observed which restricted the mixing of the water body, therefore pollutant entering as domestic waste water discharge from the surroundings of the pond get trapped in the epilimnion due to less or no mixing. Recapitulating the above, despite of the poor water quality, presence of active biological food chain can result in no significant adverse effects over the aquatic life.

Keywords: Water quality index; Eutrophication; Thermal stratification; Epiliminion; Gross primary productivity; Ceriodaphnia spp.