Impact of Urban Runoff on the Benthic and Pelagic Fish Fauna in Ikpoba River: Heavy Metal Levels and Gill Pathology

This study presents an assessment of the influence of urban runoff on fish fauna in the Ikpoba River, Nigeria, focusing on heavy metal contamination and gill pathology in benthic (Clarias gariepinus) and pelagic (Oreochromis niloticus) fish species. Samples of water, sediment, and fish gills were collected from June to August 2023. Heavy metals (Ni, Co, Cr, Pb, and Cd) were analyzed via Atomic Absorption Spectrometry (AAS), and gill pathology was evaluated through histopathological examination. Results indicated elevated concentrations of Cr and Ni in water samples, surpassing World Health Organization (WHO) standards, with Ni concentrations also elevated in sediments. However, heavy metal concentrations in fish gills remained below United States Environmental Protection Agency (US-EPA) thresholds for aquatic life, suggesting low contamination levels. Histopathological analysis revealed mild alterations in the gills, including blunted tips and prominent lacunae, attributed to metal presence. The study underscores the ecological and human health risks associated with heavy metal contamination in the Ikpoba River due to urban runoff. Findings stress the necessity of regular water quality monitoring to protect the river ecosystem. This research contributes to understanding the impact of urbanization on aquatic environments and provides insights for effective environmental managemen