Assessment of Heavy Metal Contamination in Fish from Warri River, Delta State

This study assessed the concentrations of heavy metals in fish tissues collected from the Warri River, Delta State, South South Nigeria, in the context of ongoing petroleum industry activities in the region. Heavy metal contamination from oil spills, industrial effluents, and urban waste discharge poses serious risks to aquatic biodiversity and human health through fish consumption. Fish samples of Tilapia zillii, Chrysichthys nigrodigitatus, and Ethmalosa fimbriata were collected from five sampling points along the Warri River and analysed for lead (Pb), cadmium (Cd), mercury (Hg), zinc (Zn), and copper (Cu) concentrations using atomic absorption spectrophotometry. Water and sediment samples were also analysed for comparison. Results showed that Pb and Cd concentrations in fish muscle tissue exceeded the maximum permissible limits established by the Food and Agriculture Organization and the World Health Organization in samples from three of five stations. Mercury levels were highest near industrial discharge points, reaching 0.62 mg/kg wet weight in Chrysichthys nigrodigitatus. Zinc and copper levels were within permissible ranges at all stations. A biomagnification trend was observed, with higher metal burdens recorded in predatory species. Sediment metal concentrations correlated positively with fish tissue burdens. The study raises public health concerns for communities consuming fish from the Warri River and recommends enforcement of pollution control regulations and continued biomonitoring in petroleum-impacted river systems. Keywords: heavy metals, fish contamination, Warri River, petroleum pollution, food safety