Document Type : Primary Research paper
In the present study, sublethal toxic effects of crude oil on the biochemical and hematological parameters of Beluga (Huso huso) were studied. Two hundred juvenile Beluga (120±30g) were supplied by Rajaei fish farm in Mazandaran Province, Iran. Specimens were exposed to the sublethal concentrations of crude oil, including 0, 0.218, 0.327 and 0.436 ppm (equals to control group, 2, 3 and 4 times more than the concentration in Caspian Sea water respectively). Hematological and biochemical parameters were measured once a week for 9 weeks (63 days) of exposure. Results showed the White Blood Cell (WBC), Red Blood Cell (RBC), Hematocrit (Ht) and Hemoglobin (Hb) decreased and Mean Corpuscular Volume (MCV) and Mean Corpuscular Hemoglobin (MCH) were mainly significantly higher in fish exposed to crude oil concentrations compared to control group. A biphasic response was observed in their value throughout the study period. Results of the leukocyte numbers showed that, eosinophil numbers increased, while lymphocyte numbers decrease in comparison to the control group and during the experiments. Monocyte numbers showed no significant differences (except 49th and 63th day) while the neutrophil numbers were higher in treatment groups than the control. Biochemical parameters showed an increase in serum glucose and other parameters including total protein, Alanine Aminotransferase (ALT), Alkaline Phosphatase (ALP) and Lactate Dehydrogenase (LDH) activities were decreased in treatment groups and mainly during the experiments. The alterations of these parameters can be used as suitable biomarkers in monitoring of crude oil pollution in the aquatic environment and to protect aquatic life.