Impact of laboratory exposure to light Arabian crude oil, dispersed oil and dispersant on the gills of the juvenile brown spotted grouper (Epinephelus chlorostigma): A histopathological study

The present study investigated the impact of subchronic exposure of the water accommodated fraction (WAF) of light Arabian crude oil, dispersed oil and dispersant on the gills of the juvenile brown spotted grouper (Epinephelus chlorostigma), observing several histopathological lesions at different time points and different concentrations. Significant alterations, compared to the control groups (p < 0.05), in four health categories (circulatory, proliferative, degenerative and inflammatory) were identified. Evaluations of histopathological lesions in gill tissue were carried out following 3, 6, 9, 12, 15, 18 and 21 days of exposure. The main lesions observed were circulatory (lamellar aneurysms, vasodilatation and hemorrhage), degenerative (edema, lifting of lamellar and filamentary epithelium and epithelium necrosis), proliferative (hypertrophy and hyperplasia of epithelial, mucous and chloride cells, fusion of adjacent lamellae), and inflammatory (lymphocytic infiltration). These results provide a tool for evaluating reclamation initiatives, such as the use of dispersants, and lead to better risk evaluations and environmental health in natural and reclaimed systems.

► Histopathological lesions were studied in juvenile Epinephelus chlorostigma under laboratory conditions.
► Dispersed oil was more toxic than crude oil or dispersant to the gills of the juvenile Epinephelus chlorostigma.
► The Epinephelus chlorostigma gills exhibited significant increase (p < 0.01) in mucous cell hypertrophy and hyperplasia.
► The juvenile Epinephelus chlorostigma exhibited significant increase in lamellar width and basal epithelial thickness.