Cortisol and Lactate dehydrogenase alternation in juvenile Caspian Kutum (Rutilus frisii) exposed to crude oil pollution

Caspian Kutum is a native and economic species of the Caspian Sea in the southern parts and due to the oil extraction, is at risk to pollution via different ways. Among the different types of pollutants, petroleum (hydrocarbons) is one of the most important pollutants in the aquatic environment. The present study aimed to find the acute effects of water-soluble fraction of crude oil (WSF) on some physiological parameters of Rutilus frisii at different time. Two treatments included two concentrations of WSF in three replicates and 120 hours was considered in the experiment. Eighty fish (average weight 0.77 ± 0.06 g) was introduced in aquarium with the dimensions of 50×30×70cm. In each aquarium, 70 L WSF solution was added with above mentioned concentrations. Lactate dehydrogenase activity and whole-body cortisol in 15 fish were measured for 0, 6, 12, 24, 48, 72, 96, 120 h. Analysis of variance showed significant differences in the interaction between cortisol concentration and time and also time was observed in 95% significance level (P0.05) but difference in time was seen in 95% level (P