Chromosomal and histopathogical alterations in Clarias gariepinus (Siluriformes, Clariidae) following exposure to Shea butter effluent

Background: Aquatic ecosystems have been a consistent recipient of industrial effluents capable of inducing genotoxic and histopathological effects on aquatic organisms if untreated.

Objectives: The aim of this study was to examine the genotoxic, using chromosomal aberration (CA) assay, and histopathological effects of Shea butter effluent (SBE) on Clarias gariepinus; one of the most widely consumed fish in Nigeria.

Methods: Fish were exposed to different lethal concentrations (0.00, 0.045, 0.050, 0.055, 0.060 g/l) for 96 hours and varying chronic concentrations (0.00, 0.0045, 0.0050, 0.0055, 0.0060 g/l) of SBE for 14, 21 and 28 days after range finding test. Fish were intraperitoneally-injected with 0.05% colchicine 2-3 hours before sacrifice. Physico-chemical parameters and heavy metal contents of the SBE were determined using standard procedures. After exposure, fish were sacrificed and dissected to remove the gills, liver and kidney from both the experimental and control groups. These organs were analysed for chromosomal aberrations and histopathological lesions.

Results: There was a significant increase in CA frequency (P < 0.05) induced by SBE in gills, liver and kidney among the treated groups compared with the control. Various types of CA observed were chromatids gaps and deletions, acentric, dicentric and ring chromosomes. Histopathological analyses revealed epithelial lifting, necrosis, lamellar fusion, oedema and haemorrhage in the gill, while vacuolation, hyperplasia, sinusoids, hypertrophy and necrosis were observed in the liver.

Conclusion: This study suggests that untreated SBE contains potentially genotoxic and clastogenic substances capable of inducing DNA damage and histopathological lesions in C. gariepinus.