Seasonal Variations in Physico-Chemical Parameters and Zooplankton Diversity of Kot Dam, Rajasthan

Abstract The present investigation was carried out to evaluate the seasonal and annual fluctuations in the physico-chemical characteristics and zooplankton diversity of Kot Dam, Rajasthan, during the period July 2021 to June 2023. Water samples were collected from four sampling sites (S1, S2, S3, and S4) during summer, monsoon, and winter seasons. A total of 21 physico-chemical parameters and the composition of zooplankton communities were analyzed to understand the ecological status of the reservoir. The study revealed marked seasonal variation in water temperature, pH, transparency, dissolved oxygen, free carbon dioxide, nutrient concentration, dissolved solids, conductivity, and alkalinity. Statistical analysis indicated significant seasonal, spatial, and year-wise variations in several parameters. Zooplankton analysis revealed the occurrence of 43 species belonging to Protozoa, Rotifera, Cladocera, Copepoda, Ostracoda, and aquatic insects/arachnids. Rotifera emerged as the dominant group, followed by Cladocera and Copepoda. Zooplankton abundance was generally higher during summer and lower during monsoon, reflecting the influence of water quality and hydrological conditions. The results indicate that Kot Dam is a moderately productive freshwater ecosystem with appreciable biological activity and seasonal nutrient enrichment. The study emphasizes the importance of continuous limnological monitoring for ecological assessment and sustainable management of reservoir ecosystems. Keywords: Kot Dam, water quality, zooplankton, seasonal variation, limnology, freshwater ecology