Diversity and Community Structure of Benthic Macroinvertebrates in Kaduna River, Kaduna State, North West Nigeria

This study examines the diversity and community structure of benthic macroinvertebrates in the Kaduna River, Kaduna State, located in Nigeria's North West geopolitical zone. The Kaduna River is the primary water source for millions of people and supports artisanal fisheries, but its ecological status is under increasing threat from agricultural runoff, domestic wastewater, and industrial effluents. Benthic samples were collected using standard D-frame kick nets and Surber samplers at six stations from upstream to downstream over two seasons. Macroinvertebrates were identified to family level and BMWP scores calculated. Physicochemical parameters were measured concurrently. A total of 44 macroinvertebrate families were recorded. Upstream stations showed diverse EPT taxa (ASPT 5.2), indicating good water quality, while downstream stations near Kaduna city showed dominance of tolerant Chironomidae and Oligochaeta (ASPT 2.4), indicating heavy organic pollution. Seasonal variation was moderate, with higher diversity in the dry season when pollutant dilution was lower and species habitat requirements were most constrained. PCA revealed biochemical oxygen demand and total dissolved solids as the primary axes of variation in community composition. The study confirms progressive downstream ecological deterioration in the Kaduna River attributable to inadequately treated urban effluents and recommends upgrading of municipal wastewater treatment before any expansion of industrial discharge permits. Keywords: benthic macroinvertebrates, Kaduna River, water quality, BMWP, bioindicators.