Deciphering urban freshwater health through integrated assessment of benthic macroinvertebrate assemblage and physicochemical dynamics in artificial ponds of Prayagraj, India

Abstract Benthic macroinvertebrates serve as effective bioindicators for assessing freshwater ecosystem integrity due to their differential sensitivity to pollution and habitat variability. This study evaluates spatial variation, taxonomic composition, and functional traits of macroinvertebrate communities in two artificial freshwater ponds located within the Botanical Garden of CMP Degree College (S1) and the University of Allahabad (S2), Prayagraj, India. Monthly sampling was conducted over six months (November 2023–April 2024), integrating biological and physicochemical assessments. A total of ten macroinvertebrate orders belonging to Arthropoda, Annelida, and Mollusca were recorded, with insects contributing the highest abundance—67.33% at S1 and 75.43% at S2. Physicochemical analysis indicated organic pollution stress at both ponds, characterized by low dissolved oxygen and elevated total hardness, particularly at S2. However, biotic indices such as the Hilsenhoff Biotic Index (HBI) and Ephemeroptera–Plecoptera–Trichoptera (EPT) richness suggested relatively better ecological quality at S2 than S1, reflecting a divergence between physicochemical and biological indicators. Functional Feeding Group (FFG) composition showed the dominance of predators, scrapers, and collector-gatherers at S1, indicative of a detritus-influenced environment, whereas S2 exhibited a higher proportion of passive filter feeders, consistent with improved water clarity and circulation. Overall, neither pond was found to be critically degraded; however, the study underscores the influence of localized environmental drivers and the necessity of integrated, site-specific management approaches in urban freshwater habitats.