KHODABANDEH, Saber*; SHAHRIYARI, Mohsen; Univ. of Tarbiat Modarres; Univ. of Tarbiat Modarres: Accumulation and the toxic effects of Mercury on survival and gill structure of Mugil auratus

Mugil auratus (1-3 gr) were exposed to different concentration (30, 70, 140 and 600 ppb) of mercury for 4 days. After exposure, Mugil gills were removed and analyzed for accumulated Hg. The structure and ultrastructure of gill investigated by light and electron microscopy and the branchial chloride cells were identified by Na+,K+-ATPase immunocytochemistry. Mercury accumulation in gills exposed to different levels of mercury (0, 30, 70, 140 and 600 ppb) was 594.547, 1403.991, 2681.150, 4768.933 and 47033.364 ppb, respectively. Between 1 and 96 hours, as fish were exposed to increasing concentrations of mercury, their survival decreased from 98% to 0%. The number of stained chloride cells increased but Na+,K+-ATPase specific immunoreactivity decreased. We observed necrotic and apoptotic chloride cells in the filaments. In conclusion the survival rates of Mugil auratus decease significantly as the concentration of mercury in the system increases. The observations arise from this study, including possible binding mechanisms of mercury and osmoregulation inhibition processes. Mercury increases percentages of immature, apoptotic and necrotic chloride cells and decreased Na+,K+-ATPase activity.