Study on the effects of ecological attributes on fish diversity in anthropogenic zone of Ganga River

The Ganga River is one of India's most sacred and ecologically significant rivers, supporting millions of people and a rich diversity of aquatic species. However, increasing anthropogenic pressures, including pollution, habitat degradation, and overfishing, have adversely affected its ecological integrity and fish diversity. The study, conducted between 2022 and 2024 at nine strategically selected sites covering 340 km from Kanpur to Ramnagar, examined the relationship between water quality and fish diversity to inform conservation and management efforts. In nine locations, seasonal fish sampling and water quality assessments were carried out three times a year during the post-monsoon, post-winter, and post-summer seasons, for a total of 27 sample events. Physicochemical parameters such as pH, dissolved oxygen (DO), biochemical oxygen demand (BOD), chemical oxygen demand (COD), and total dissolved solids (TDS) were measured using established techniques. Multivariate statistical techniques, namely Principal Component Analysis (PCA) and Canonical Correspondence Analysis (CCA), were employed to investigate environmental–biological relationships. The study found considerable seasonal and regional differences in water quality, with pH varying from 6.8 to 8.2, with lower values during the monsoon owing to runoff. DO levels fluctuated between 4.0 and 8.5 mg/L, with winter being the highest and summer being the lowest. BOD levels were between 4.2 and 6.5 mg/L, with urban-industrial locations having the highest concentrations. COD levels varied from 10 to 35 mg/L, with TDS peaking at Site 1 (504.56 mg/L), suggesting a considerable anthropogenic input. PCA and CCA found three significant components that accounted for 82.3% of total variation, with pollution, hydrological conditions, and human disturbance as key drivers. The data highlight how diminishing water quality and habitat changes affect fish diversity in the Ganga River.