Impact of Urban Runoff on Benthic and Pelagic Fish Fauna in Ikpoba River: Heavy Metals and Pathology of Liver Tissues

Abstract

This study investigates the impact of urban runoff on benthic and pelagic fish fauna in the Ikpoba River, focusing on the effects of heavy metals on liver tissues. The research was conducted in Benin City, Nigeria, where the river is central to local livelihoods but faces pollution threats due to proximity to waste disposal and industrial effluent sites. Water, sediment, and fish samples were collected from two sampling stations along the river. The concentrations of heavy metals (Cr, Co, Cd, Ni, Pb) in these samples were analyzed using an Atomic Absorption Spectrophotometer. Histopathological examinations of fish liver tissues were also conducted. Results revealed the presence of heavy metals in the water and sediment samples, with significant concentrations of chromium upstream. Heavy metals were also found in the liver of both benthic and pelagic fishes, indicating potential environmental contamination. Histopathology of the liver tissues showed signs of inflammation and steatosis, common responses to stress or injury, such as that caused by heavy metal exposure. These findings underscore the need for ongoing monitoring and management of the river’s health.