Ecological health assessment of a municipal river in North-Central Nigeria using macroinvertebrate assemblages and environmental variables

Freshwater ecosystems such as rivers, streams, and lakes are biodiversity hotspot and are of global ecological importance but increased human population have exerted significant pressure on these unique resources. This study assessed the ecological health of Etswan River using integrated habitat quality, physicochemical characteristics and macroinvertebrate assemblages for eight months (July 2025 to February 2026). Four sampling stations were selected long the river reach and were investigated using standard ecological and statistical approaches. Qualitative Habitat Evaluation Index (QHEI) scores ranged from 54% to 68%, indicating an ecologically stressed but viable system. Most of the physicochemical parameters were spatially uniform indicating a relatively homogeneous environment except for dissolved oxygen, depth, and total hardness that showed significant difference (p < 0.05) between the sampling stations. A total of 659 macroinvertebrate individuals from 24 species were encountered and the most abundant group was Hemiptera, followed by Mollusca and Odonata. Diversity indices indicated that there was a moderate level of species diversity among the stations as station 4 recorded the highest (19 species) in term of number of species while station 3 recorded the lowest (16 species). Station 1 had the highest number of individuals (214) followed by station 3 (157), station 4 (151) and the lowest number of individuals (137) was observed in station 2. Canonical Correspondence Analysis (CCA) showed that the dissolved oxygen, depth and nutrient concentrations had a significant effect on the distribution of the macroinvertebrates (p < 0.05) with more than 85% of the total variation accounted. Our findings show that although the river still possesses certain ecological integrity, rising anthropogenic activities are gradually altering habitat structure, deterioration of water quality, changes in macroinvertebrate community structure, reduced biodiversity, and increased dominance of pollution-tolerant taxa, although there is need for continuous monitoring of the river for sustainable management of the ecosystem.