R. Kazempoor - Department of Biology, Roudehen Branch, Islamic Azad University, Roudehen, Iran.
A. Haghighi Khiabanian Asl - Department of Pathobiology, Science and Research Branch, Islamic Azad University, Tehran, Iran
A.A. Motallebi - Department of health, Science and Research Branch, Islamic Azad University, Tehran, Iran
E. Alaie - Research Institute of Petroleum Industry (RIPI), Tehran, Iran

Water soluble fraction (WSF) of crude oil can pollute water and cause histopathological alterations in fishes. Therefore, sea water pollution with crude oil could detrimentally impact the fish health. The aim of the present study was to evaluate the effect of different concentrations of WSF on gills of yellow fin sea bream. The fish were exposed to ۰% (control), ۲%, ۴%, ۸% and ۱۶% of WSF for a period of ۲۱-days. The histopathological alterations were examined in four categories of circulatory, degenerative, proliferative and inflammatory. Inclusion of WSF at concentrations of ۴%, ۸% and ۱۶% led to significant elevation of total petroleum hydrocarbon concentration in water (p<۰.۰۵). In the ۸% group, the changes in histopathological lesions observed from day ۱۶ compared with control group (p<۰.۰۵). In the ۱۶% group, increasing histopathological lesions was observed from day ۸ compared with the control group (p<۰.۰۵). However, no significant increase in histopathological lesions was observed in fish exposed to ۲% and ۴% WSF as compared with the control group (p>۰.۰۵). In conclusion, the findings of the present study indicated concentration and period of exposure as determinant factors influencing the level of alterations in gills histopathological lesions following exposure to WSF in yellow fin sea bream.  

Iranian crude oil, Yellow fin sea bream, Histopathology, Water soluble fraction, Gill