Assessment of Oil Spill Impact on Fish Diversity in Creeks of Ogoniland, Rivers State

Oil spills in the Niger Delta have resulted in widespread ecological damage, with fish communities among the most acutely affected components of aquatic biodiversity. This study assessed the impact of oil spill events on fish species diversity and abundance in selected creeks of Ogoniland, Rivers State, South South Nigeria. Fish sampling was conducted at spill-impacted and reference sites using cast nets, gill nets, and experimental traps over a period of five months. Fish species were identified, counted, and weighed, and community diversity indices were calculated. Water quality parameters including total petroleum hydrocarbon, dissolved oxygen, pH, and turbidity were measured at all stations. A total of 38 fish species from 20 families were recorded across both spill-affected and reference sites. Reference sites supported significantly higher species richness and total abundance compared to spill-impacted areas. Clupeid and cichlid species, which are ecologically sensitive, were absent or rare at polluted stations. Dominant species at oil-affected sites were pollution-tolerant catfishes and mudskippers. Total petroleum hydrocarbon concentrations exceeded FEPA permissible limits at all impacted sites. The Bray-Curtis similarity index revealed stark compositional differences between reference and impacted communities. Interview data confirmed that local fishers have experienced declining catches over the past five years, corroborating biological findings. The study advocates for expedited remediation of Ogoniland creeks and monitoring of fish community recovery following cleanup operations. Keywords: oil spill, fish diversity, Ogoniland, total petroleum hydrocarbons, Niger Delta.