Assessment of Ecological Quality Based on Benthic Macro-invertebrates in the Ganga River, Patna

The present study was carried out to assess the impact of environmental variables and stressors on the assemblage and distribution of benthic macro-invertebrates. For this purpose, water samples and benthic fauna were collected seasonally from four sampling stations over a 36-km-long stretch of the Ganga River from 2015 to 2017. The study results revealed the alkaline nature of water and the total hardness observed in all samples fall under moderately hard to hard category. The abundance, richness, Shannon diversity index and evenness were calculated to evaluate the structure of benthic macro-invertebrate communities. The Shannon diversity and Ganga River System Biotic Score (GRS-bios) index indicates the ecological status of the sampling sites ranged from moderately to extremely polluted. Multivariate statistical techniques, such as principal component analysis, were carried out on the chemical variables. The result of CCA has clearly revealed the role of environmental variables over benthic fauna assemblage, and these faunas were found to be sensitive to inorganic pollutant load.