Blood lead level as biomarker of environmental lead pollution in feral and cultured African catfish (<i>Clarias gariepinus</i> )

Abstract

Research has demonstrated a positive link between the presence of lead in freshwater, sediments or food organisms and the onset of sub-lethal effects characterized by neurological defects, kidney dysfunction, endocrine disruption, reproductive/developmental defects, behavioural abnormalities and anemia in demersal aquatic fauna. Considering the significance of haematological parameters as indicators of fish health, this present work assessed the blood lead level (BLL) and haematological parameters of feral and cultured African catfish (Clarias gariepinus) in Ibadan, a metropolitan city. BLL and haematological parameters of fifty Clarias gariepinus were determined. Each set of ten fish were randomly collected from three different fish ponds and two rivers. BLL was relatively higher in feral fishes than those from fish ponds; while all the haematological parameters (PCV, HB, RBC, MCH, MCV and MCHC) were non-significantly (p<0.05) higher in fishes sourced from cultured environment relative to those from surface water and vice versa for immunological parameters (WBC and differential counts). The BLL observed in this study (0.85 ± 0.38 mg/dl and 0.90 ± 0.6 mg/dl) from cultured and feral fish respectively is indicative of lead pollution of the culture water and environment. The ideal blood lead level is now considered to be zero. Lead pollution of the study area has serious consequences on aquatic fauna and humans who consume such contaminated fish. It is therefore recommended that human and animal health surveillance and environmental monitoring of lead should be initiated.