Background and aims: Antioxidant defense plays a vital part in organism protection against oxidativestress which is produced by reactive oxygen species (ROS).
Oxidative stress represents a serious threatto the animals facing with heavy metals. This study was designed to analyze the habitat suitability forCaspian pond turtles, namely, Mauremys caspica in Mazandaran province by measuring lead (Hg) andmercury (Pb) tissues concentrations and heavy metals’ effects on the health status of Caspian pondturtles through quantifying the oxidative stress factors.Methods: Hg and Pb were measured in kidney and liver tissues of ۲۰ sampled Caspian pond maleturtles (treatment group) using atomic absorption spectrometry (AAS) and a Caspian pond male turtlewas included in the control group. Moreover, glutathione (GSH) level, catalase (CAT), and superoxidedismutase (SOD) activities were investigated in kidney and liver tissues.Results: The mean (SD) concentration of Pb and Hg were ۳۵.۸۳ (۴.۲۰), and ۰.۶۰۴ (۰.۰۳) mg/kg forthe sampled livers and also ۳۱.۰۱ (۳.۴۲) mg/kg and ۰.۳۱۶ (۰.۰۴) mg/kg for the sampled kidneys,respectively. Levels of trace elements, CAT, and SOD activities were found to be higher in the liver.Totally, GSH levels, as well as, CAT, and SOD activities were found to be higher and lower, respectively,in the control turtle as compared with the contaminated Caspian pond turtles. Trace-element levelshad a positive correlation with CAT and SOD activities while having a negative association with GSHlevels in contaminated Caspian pond sampled turtles.Conclusion: According to the results, it was inferred that high Hg and Pb concentrations in the turtleswere due to the heavy metal contamination of their habitat in Mazandaran province. Based on thepositive correlation between the heavy metal concentration of the tissue and dysfunction of oxidativestress defense markers, it can be concluded when the Caspian pond turtles are faced with heavy metalcontamination risk, these markers can act as a bioindicator of their health status. No doubt, morestudies are required to prove this hypothesis.