Heavy metal bioaccumulation in the macroinvertebrate functional feeding guilds of an impaired stream in South-West Nigeria

Anthropogenic impacts and the accumulation of heavy metals in water bodies have increased significantly as a result of increased urbanisation, endangering both aquatic biota and human health. The pace of urbanisation and its attendant freshwater ecosystem pollution in Nigeria is so fast that there are concerns for the nation’s freshwater biota. To this end, six heavy metals were investigated in the water column, sediment, and tissues of macroinvertebrate functional feeding guilds (FFGs) of a Nigerian stream. Three heavy metals that are non-essential (As, Cd, and Pb) exceeded their WHO permissible limits for surface fresh waters. According to the geo-accumulation index (Igeo) and contamination factor (CF) used to assess heavy metal pollution, there was a high level of Cd contamination among all heavy metals found in the sediment. These heavy metals were all biomagnified (>1), especially among the predators. The study concluded that Opa Stream was moderately impacted based on the concentrations of heavy metals in the stream’s water column, sediment, and macroinvertebrate tissues. Future research works can consider the remediation of heavy metals that are non-essential in freshwater systems to ensure the sustainability of freshwater biodiversity and human health.