摘要:This paper deals with study of physico-chemical climatic changes in the river water of Son along the Bhojpur stretch during a period of 18 months from March 2014 to August 2015. It also deals with interrelationship between the changes in climatic factors with plankton diversity in the river. Thermometric factors have been found to be most remarkable showing inverse relationship with plankton diversity upto a limit. Low dissolved oxygen has been related with high plankton production especially cyanophyceae and copepods. Dominance of cyanophyceae and copepods, low dissolved oxygen, high COD and high phosphate contents indicate river being under stress and organic pollution. Different community diversity parameters like Species Diversity Index (H), Richness Index (S), Evenness Index (J) and Dominance Index (D) also report the fact that the river is under stress and Zooplankton being found more responsive to physicochemical climate changes than Phytoplankton in the river.