Benthic Macroinvertebrate Communities as Bioindicators of Pollution in Qua Iboe River, Akwa Ibom State

Benthic macroinvertebrates are widely recognized as reliable biological indicators of water quality because of their sedentary lifestyle, variable pollution tolerance, and measurable community responses to environmental stress. This study evaluated the composition and bioindicator status of benthic macroinvertebrate communities in the Qua Iboe River, Akwa Ibom State, South South Nigeria. Samples were collected from six stations representing varying degrees of anthropogenic influence using a Surber sampler during wet and dry seasons. Specimens were identified to family level and sorted using standard procedures. The Biological Monitoring Working Party score and the Shannon diversity index were applied to assess ecological status. Water quality parameters including biochemical oxygen demand, total dissolved solids, nitrate, and phosphate were also measured. A total of 41 macroinvertebrate families were recorded. Stations near oil flow stations and agricultural discharge zones were dominated by pollution-tolerant Chironomidae and Oligochaeta, while sensitive Ephemeroptera and Plecoptera taxa were restricted to upstream reference sites. BMWP scores classified the lower stations as doubtful to fairly poor, indicating significant organic and chemical pollution. The Shannon index ranged from 0.89 to 2.76, reflecting a degradation gradient from downstream to upstream stations. This study underscores the effectiveness of macroinvertebrates as cost-efficient biomonitoring tools and advocates their integration into routine environmental compliance assessments in the Niger Delta corridor. Keywords: benthic macroinvertebrates, bioindicators, Qua Iboe River, BMWP score, pollution.