DIVERSITYANDSEASONALVARIATIONOFPLANKTONINKOSI RIVER OF STATE UTTARAKHAND, INDIA

Thisstudyexaminestheseasonalvariations and planktondiversityintheKosiRiverintwodistricts of the state of Uttarakhand. One of the most crucial ecological factors in determining the quality of water is plankton diversity, which also serves as a reliable indication of alterations in water quality. Since they are at the base of the food chain and represent a large source of organic carbon that is physiologically significant, planktons are fundamental components of the aquatic community. Samples were taken between January and December of 2021 in order to determine the plankton's diversity. At sampling points, phytoplanktonbelongingto61generaandzooplanktonbelongingto25genera.Thehuman activities in and around the river have resulted in a sharp decline in biodiversity overall. Present study examined the potential for algal bio-monitoring across a gradient of agriculturally impacted streams and to conserve the planktons which are declining day by day. In phytoplankton diversity bacillariophyceae (58%) was most dominant group which is followed by chlorophyceae (39%) and Cyanophyceae (3%). In terms of zooplankton, rotifera (44%) was most dominant followed by protozoa (36%) cladocera (16%) and Copepoda (4%).