UTTAR PRADESH JOURNAL OF ZOOLOGY

The present study aims to assess the effect of agricultural fertilizers on phytoplankton and zooplankton distribution and density in the freshwater culture ponds in Krishna District of Andhra Pradesh. Planktons were microscopic organisms those harbor all aquatic environments. Study samples of water were mainly collected from the three culture ponds located in Krishna area, Andhra Pradesh to assess the quantitative distribution of plankton and qualitative capacity to maintain a good health condition under fertilizer stress conditions. Samples were collected in the months of August, October and December-2024. The phytoplankton density is directly interconnected with the production in an aquatic environment and appropriate water quality management and the physico-chemical factors were directly linked with their production. Further, fertilization directly affects the quality of water; maximum phosphorus levels were reached to 5.4 mgL^-1 in December and the maximum rates of ammonia were reported to 0.42 mgL^-1 in both October and December months. The very common species of phytoplankton species reported were Lauderia, Chlorella, Cyclotella, Navicula, Oscillatorials, Thalassiosirales, Cylindrotheca, zooplankton species are Rotifera, copepods, Moina, Cyclops and Blue-green algae were Microcystis, Oscillatorials, Merismopedia and Spirulineaceae. Significant differences were reported (p<0.05) in dissolved oxygen, ammonia content, total phosphorus levels, and levels in the orthophosphate, nitrite and nitrate between ponds. It is also reported that a significant difference (p<0.05) in dissolved oxygen and pH between the ponds’ surface and bottom. The results also showed a significant difference in the plankton distribution and density between fertilized and non-fertilized ponds.