The purpose of the present study was to evaluate the effects of exposure to waterborne sublethal cadmium (Cd) concentration on juvenile Persian sturgeon, Acipenser persicus. Fish were exposed to 0.68 mg/l of Cd for 1, 7, and 14 days, and metal bioaccumulations, biochemical responses, and gill ions were investigated. There were significant differences (p<0.05) in the kidney (1, 7, and 14) and gills (7 and 14) for Cd concentrations between the control and treatment groups. Also, kidney Cd concentrations were significantly higher (p<0.05) at metal treatments on day 14 in comparison to day 1. Results showed that there were significant differences (p<0.05) in plasma glucose and cortisol concentrations between the experimental and control groups on day 1 only, and at metal treatments, a significant decrease (p<0.05) was observed on days 7 and 14 compared to day 1. No significant alterations were observed in plasma and liver protein contents during the course of the study. Neither triiodothyronine or thyroxine levels nor liver catalase or glutathione-S-transferase activities changed significantly with sublethal dose and with the time. In contrast, liver superoxide dismutase activities were significantly decreased (p<0.05) at Cd treatments both over the control group and during Cd exposure on days 7 and 14. Finally, a comparison between the groups revealed no differences in gill ion levels for 2 weeks. This study demonstrated that sublethal dose of Cd was stressful for Persian sturgeon and resulted in rapid changes in some of the biochemical parameters.

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