Utilisation of biotic and abiotic components in the ecological assessment of the Ossiomo River, Edo State, Nigeria

Fish (Gymnarchus niloticus) and sediment samples were used as bioindicators of heavy metal contamination in the ecological assessment of the Ossiomo River. These samples were collected monthly (August 2021 to January 2022) and analysed for heavy metal content using standard methods. Results from this study showed that both the sediment and fish were contaminated with heavy metals. Heavy metal concentration profile of Fe > Zn > Mn > Cu > Pb > Cr > Cd was observed in the sediment. Bioaccumulation factor (BAF) for heavy metals in G. niloticus were > 1, with an order of Cd > Zn > Mn > Cu > Cr > Fe > Pb (gills); Cu > Cd > Zn > Cr > Mn > Fe > Pb (liver), and Mn > Zn > Cu > Cr > Fe > Cd > Pb (muscles). The pollution load index (PLI) values across the three study stations indicate that there is heavy metal pollution of the sediment (PLI > 1). Potential ecological risk index (PERI) assessment showed that stations 1 and 3 exhibited considerable ecological risk (300 < RI ≤ 600), while station 2 indicated a very high ecological risk (RI > 600). There is a need for periodic water quality assessment and monitoring of human and industrialactivities within the Ossiomo River catchment area in order to forestall further deposition of more pollutants into the river and protect public health.