Bioaccumulation of Heavy Metals in Pelagic and Benthic Fishes of Ogbese River, Ondo State, South-Western Nigeria

The bioaccumulation factors (BAFs) of heavy metal (Fe, Zn, Pb, Cd, Cr, Cu, Mn, and As) concentrations in benthic and pelagic fish organs (muscles, gills, liver, and hearts), and concentrations of heavy metals in water and sediments of Ogbese River, Ondo State, Nigeria were investigated. From the results, the concentrations of heavy metals in the water were within the permissible limits stipulated by the World Health Organization (WHO). However, in the sediments, Cd, Cr, Fe, and Mn concentrations were higher than the limits, while Zn, As, Pb, and Cu were within limits. Heavy metals concentrations in the fish organs showed that all fish species were within the permissible limits implying no contamination. More so, the BAFs in all fish organs revealed no probability of accumulation while the geoaccumulation index and contamination factor showed no contamination to moderate contamination. The potential ecological risk index also showed moderate risk factor indicating that the water and sediments were not extremely polluted for higher organisms but may be toxic for lower ones. The study concludes that constant monitoring and study should be conducted by researchers and the Ministry of Water Resource and that the community should be aware of the danger human pollution can cause to the river.

Automated summary

The study found that heavy metal concentrations in the water and sediments of Ogbese River in Ondo State, Nigeria were mostly within permissible limits set by the World Health Organization. Heavy metal concentrations in fish organs also did not exceed limits, indicating no contamination. The potential ecological risk index showed moderate risk, suggesting that the water and sediments were not extremely polluted for higher organisms but may be toxic for lower ones.