Histopathological liver alterations in juvenile rabbit fish (Siganus canaliculatus) exposed to light Arabian crude oil, dispersed oil and dispersant

Abstract

With the heavy transport of crude oil there is an increasing risk of a major oil spill in the Gulf waters; however, there have been few studies on the impact of oil spills and subsequent remedial action on Gulf fish. The aim of the experiment was to investigate the effects of acute exposure to water soluble fraction (WAF) of light Arabian crude oil, dispersed oil and dispersant on the liver of the juvenile rabbit fish (Siganus canaliculatus), observing several histopathological biomarkers of the liver at different time points and different doses. The concentrations used (3-100 percent WAF) simulated a range of possible oil pollution events. The main alterations observed in this study include hepatocyte swelling and cytoplasmic vacuolisation, megalocytosis, coagulative dispersed necrosis, lymphocytic infiltration, melanomacrophage aggregates, spongiosis hepatis, pericholangiitis, and bile stagnosis. Treated livers showed significantly higher total index values than the control group (p<0.01). According to the total liver index, liver exposed to WAF, dispersed oil or dispersant showed significant histopathologic alterations compared with the control fish (Mann-Whitney U-test; p<0.01). Components of the total liver index, (circulatory, degenerative, proliferative, and inflammatory changes) differed significantly from the control groups. There was a significant correlation between exposure time and the total liver index values and the different reaction pattern indexes of treated fish (Spearman correlation; p>0.05). The present study indicates that dispersed oil is not more toxic, to livers of juvenile rabbit fish, than crude oil or dispersant.