Ecotoxicological Impact of Sub-lethal Concentrations of Glyphosate–based Herbicide on Juvenile Clarias gariepinus

Abstract

The presence of pesticides in both aquatic and terrestrial ecosystems has become an important issue globally. This study determined the possibility of bioaccumulation of glyphosate, the active compound of Roundup pesticides in muscle tissues of juvenile Catfish (Clarias gariepinus), and the effects of exposure on some oxidative stress parameters. Forty fishes were grouped and exposed to graded (sub-lethal) concentration of Roundup pesticides for two weeks. Pesticides were extracted from the muscle tissues by cold extraction and detection and determination were performed using Gas chromatography- Electron captured detector (GC-ECD). Oxidative stress parameters such as catalase, superoxide dismutase, reduced glutathione, glutathione peroxidase and malondialdehyde were analyzed. Fish tissue glyphosate concentration increased significantly (p<0.05) as dosage increased and residues of organochlorine pesticides such as p-p1DDT, p-p1DDE, HCB, α-HCH, γ-HCH, t-nonachlor and γ-chlordane were detected at concentration far below the provisional tolerable daily intake (PTDI) value. The biochemical studies showed significant increase (p<0.05) in activity of oxidative stress enzymes and lipid peroxidation product of fish groups exposed to Roundup pesticides in a dose dependent pattern.  This study reveals that the use of Roundup pesticides in ways that could expose aquatic environment to its residues could result to adverse biochemical changes. Therefore, the use of this pesticide should be properly regulated and monitored to limit chronic exposure of fish consumers.