Assessment of Heavy Metal and Hydrocarbon Contamination in Selected Fish Species from Major Aquatic Bodies of Bayelsa State, Nigeria

Background and Objective: Aquatic ecosystems in the Niger Delta Region are increasingly threatened by petroleum-related pollution and heavy metal contamination, raising concerns about food safety and public health. This study investigated the toxicant profiles of three economically important fish species: Clarias gariepinus (African catfish), Polydactylus quadrifilis (Giant African Threadfin), and Oreochromis niloticus (Nile Tilapia) from freshwater, saltwater, and brackish water habitats in Bayelsa State, Nigeria. Materials and Methods: A total of twenty-one fish samples (seven per species) were systematically collected from Taylor Creek (freshwater), Brass River/Atlantic Ocean (saltwater), and Nembe Creek (brackish). Heavy metals in fish and water samples were analyzed using Atomic Absorption Spectrophotometry (AAS), while hydrocarbons were assessed using Gas Chromatography-Mass Spectrometry/Flame Ionization Detector (GC-MS/FID) following United States Environmental Protection Agency (USEPA) protocols. Data were analyzed in SPSS v27 using ANOVA and Tukey’s HSD (p<0.05). Results: Significant heavy metal contamination was observed. Lead concentrations in Oreochromis niloticus (0.08±0.01 mg/kg) and Clarias gariepinus (0.06±0.01 mg/kg) exceeded WHO/FAO limits (0.01 mg/kg) by 8-fold and 6-fold, respectively. Total Hydrocarbon Content (THC) exceeded WHO/FAO standards (0.1 mg/kg) in all species: Polydactylus quadrifilis (4.43±0.39 mg/kg), Oreochromis niloticus (2.76±0.20 mg/kg), and Clarias gariepinus (0.96±0.10 mg/kg). Polydactylus quadrifilis also showed detectable concentrations of carcinogenic polycyclic aromatic hydrocarbons (PAHs), including benzo[a]anthracene (0.07±0.00 mg/kg), chrysene (0.06±0.0001 mg/kg), and benzo[a]pyrene (0.03±0.00 mg/kg), all significantly above WHO limits (0.002 mg/kg). Conclusion: Polydactylus quadrifilis exhibited the highest THC and PAH concentrations, highlighting significant bioaccumulation and the urgent need for remediation. Oreochromis niloticus from brackish waters also showed elevated levels of heavy metal contamination, underscoring the need for continuous monitoring to protect food safety and public health.