A Study on Functional Structure of Benthic Macro invertebrates of Ganga River, Hajipur, Bihar

Abstract

Benthic macroinvertebrates are among the most useful biological components for evaluating the ecological condition of riverine systems because they live in close contact with bottom sediments, respond to changes in water quality and habitat structure, and represent several trophic roles within the aquatic food web. The present analytical paper focuses on the functional structure of benthic macroinvertebrates in the Ganga River at Hajipur, Bihar, during the January-March 2026 study period. Instead of limiting assessment to taxonomic occurrence, the paper emphasizes the ecological function of macroinvertebrate assemblages through functional feeding groups, pollution sensitivity, habitat preference, and biological indicator value. The analytical framework links river habitat, substrate condition, organic matter availability, andanthropogenic pressure with the distribution of collectors, scrapers, shredders, predators and tolerant benthic forms. The paper also presents a field-oriented methodology for sampling, preservation, laboratory identification, diversity analysis and interpretation through indices such as Shannon diversity, Simpson dominance, Margalef richness, Pielou evenness, EPT percentage, Chironomidae-Oligochaeta dominance, BMWP and ASPT. The discussion suggests that functional analysis can provide a clearer ecological understanding of river health because it explains not only which organisms are present but alsowhat ecological processes are being supported or disturbed. For the Hajipur stretch of the Ganga, such an approach is particularly relevant because the river receives multiple pressures from settlement activity, bank use, religious activity, sediment disturbance and local wastewater inputs. The paper concludes that functional assessment of benthic macroinvertebrates can strengthen biological monitoring of the Ganga River and support more practical river conservation planning at local and regional levels.