Comparative Study on Seasonal Zooplankton Diversity in Two Urban Reservoirs of Warangal District, Telangana, India

Abstract

The present study assessed seasonal diversity, abundance and composition of zooplankton in two urban freshwater reservoirs, Bhadrakali and Waddepally, in Warangal city, Telangana, India, from June 2022 to May 2024. Monthly zooplankton sampling at four fixed stations per reservoir yielded 15 species in Bhadrakali and 13 in Waddepally, spanning Copepoda, Cladocera, Rotifera, and Ostracoda. Copepoda (Cyclops, Diaptomus) and Cladocera (Scapholeberis, Diaphanosoma) dominated across seasons, with peak abundance in summer and lowest densities during the monsoon. Bhadrakali consistently showed higher species richness and abundance than Waddepally, likely due to its relatively stable hydrological and physicochemical profile. Statistical analysis revealed significant correlations between zooplankton abundance and water quality parameters particularly total alkalinity, ammonia, nitrate, and phosphate with nutrient enrichment negatively affecting sensitive taxa like rotifers. Regression models confirmed these parameters significantly influenced population dynamics, underscoring the role of zooplankton as sensitive bio indicators of ecosystem health. The presence of genera such as Brachionus and Keratella indicates moderate eutrophication, especially in Waddepally. This study highlights the ecological importance of long-term zooplankton monitoring for managing urban freshwater ecosystems and provides baseline data for conservation and water quality assessment in semi-arid regions.