Influence of short-term exposure to sub-lethal concentrations of Diazinon on energetic and osmotic parameters of the Persian sturgeon juveniles, Acipenser persicus Borodin, 1897 during osmotic adaptation to seawater

In the present study, we investigated the effects of short –term exposure (96 h) and sub-lethal concentrations of diazinon on energetic (glucose, lactate) and osmotic parameters (chloride cells number, cortisol, total protein, blood plasma ions) of Persian sturgeon juveniles (Acipenser persicus) during salinity adaptation to seawater. 500 fish were distributed in twelve 100 L tanks at density of 40 fish per tank. The experimental treatments were: (1) 0.3 ppm (%10 LC50 96 h) diazinon, (2) 0.9 ppm (%30 LC50 96 h) diazinon (3) 1.5 ppm (%50 LC50 96 h) diazinon. Also, one diazinon-free group was considered as control. The experiment was conducted in two stages including: 96 h exposure in freshwater (FW) and 24 h exposure in brackish water (BW: 12 ppt salinity). After each stage, blood and gill tissue samples were taken. The results that diazinin can affect energetic and blood osmotic parameters of Persian sturgeon juveniles before and during the salinity adaptation period, especially in high concentrations (including 0.9 and 1.5 ppm). These effects includes: (a) 96 h exposure in FW: increase in cortisol, glucose, lactate and number of chloride cells (only in 0.3 ppm group) and decrease of ions. (b) 24 h exposure in BW: increase in cortisol, glucose and ions. In conclusion, our study showed that sub-lethal concentrations of diazinon (especially 0.9 and 1.5 ppm) reduce the potential of osmoregulation of the Persian sturgeon juveniles during salinity adaptation to seawater. These effects were: decreases in number of chloride cells, increases in stress indices (cortisol and glucose), changes in permeability of gills tissue and causing anaerobic condition which can affect the success of rebuilding the reserves of this precious species.