Preliminary Ecological Risk Assessment of Toxic Elements in Fish Cage Culture Sites within the Interconnected Epe and Badagry Lagoons, Nigeria

The interconnected Epe and Badagry Lagoons in Nigeria are vital ecosystems supporting fish cage culture, but they may be at risk of toxic element contamination, posing threats to aquatic life and human health. This study conducted a preliminary ecological risk evaluation, focusing on arsenic, boron, selenium, silicon, and sulfur concentrations in water, sediment, and Heteroclarias tissues using standard analytical methods. Contamination levels and ecological risks were assessed using contamination factor (CF), enrichment factor (EF), bioaccumulation factor (BAF), and the index of geo-accumulation (Igeo). Sediment consistently showed the highest concentrations of all analyzed elements, with arsenic levels in Badagry Lagoon (0.4426 ± 0.0731 mg kg⁻¹) exceeding those in water and fish tissues, and a sediment-dominant pattern was observed for boron, selenium, silicon, and sulfur. Arsenic bioaccumulation factors in Heteroclarias from Epe Lagoon were significantly high (62.29 ± 0.36 for water and 1.26 ± 0.73 for sediment), while EF values for arsenic were highest in Badagry Lagoon (29.80), and selenium showed the highest EF in Epe Lagoon (224.64). Despite negative Igeo values indicating no significant sediment contamination, elevated arsenic concentrations and bioaccumulation in fish tissues raise potential health concerns for aquatic life and human consumers, emphasizing the need for regular monitoring and management strategies to mitigate toxic element contamination in the Lagos Lagoon system.