Assessment of Deep-Sea Mining Potential and Environmental Risks in Nigeria’s Exclusive Economic Zone

Deep-sea mining of polymetallic nodules and ferromanganese crusts has attracted growing international commercial attention, and preliminary geophysical surveys suggest that Nigeria's exclusive economic zone in the Gulf of Guinea may contain mineral deposits of potential economic significance. This study assesses the prospectivity of deep-sea mineral deposits within Nigeria's exclusive economic zone and evaluates the associated environmental risks and governance implications using a multi-disciplinary research framework. Existing geophysical datasets including multibeam bathymetric surveys, sub-bottom profiles, and geochemical sampling records from previous research cruises in Nigerian waters are compiled and reanalysed to identify morphological indicators of nodule occurrence (abyssal plain flat areas with Mn-encrusted basalt outcrops) and polymetallic sulphide deposits (hydrothermal vent fields). Environmental baseline assessment for potential mining impact draws on published species distribution data for benthic invertebrates and benthopelagic fish in comparable Gulf of Guinea depths from 1,500 to 4,000 metres. Governance analysis evaluates Nigeria's regulatory capacity to manage deep-sea mining under the International Seabed Authority framework and domestic legal requirements under the Exclusive Economic Zone Act and the Nigerian Minerals and Mining Act. Ecosystem service valuation estimates the non-use conservation value of undisturbed deep-sea habitats using benefits transfer methods. Findings provide a foundational evidence base for Nigeria's emerging deep-sea mineral policy and recommend a precautionary approach prioritising environmental baseline surveys before any commercial licence issuance. Keywords: deep-sea mining, polymetallic nodules, Nigeria EEZ, environmental risks, governance