Marine Pollution Monitoring Using Mussel Watch Approach in Selected Nigerian Coastal Ports

Mussel watch programmes utilise the bioaccumulation capacity of sessile bivalves to monitor organic and inorganic pollutant levels in coastal environments, providing an integrated signal of ecosystem contamination. This study applied the mussel watch approach to monitor contaminant levels at four major Nigerian coastal ports: Lagos, Apapa, Warri, and Calabar. Oyster (Crassostrea tulipa) and mussel (Mytilus edulis) tissue samples were collected bimonthly over eight months from rocky and artificial substrate attachment points within and adjacent to each port. Tissue concentrations of polycyclic aromatic hydrocarbons, organochlorine pesticides, heavy metals (lead, cadmium, copper, zinc, mercury), and tributyltin were determined using gas chromatography-mass spectrometry and atomic absorption spectrophotometry. Concurrent water and sediment samples were also analysed. Apapa Port tissues contained the highest PAH concentrations, with naphthalene and phenanthrene as dominant compounds attributed to ship fuel residues. Lead and cadmium exceeded European Union bivalve consumption safety thresholds at Warri Port. Tributyltin, an antifouling agent, was detected in all port bivalve tissues with highest concentrations at Lagos Port. Organochlorine pesticide concentrations were below detection limits at all ports. Temporal trends showed statistically significant increases in PAH levels between the first and last sampling periods at two ports. The study establishes a replicable mussel watch protocol for Nigerian ports and recommends its integration into NIMASA's annual environmental monitoring requirements. Keywords: mussel watch, biomonitoring, port pollution, PAHs, Nigeria.