Initial salinity tolerance and ion-osmotic parameters in juvenile Russian Sturgeon, Acipenser gueldenstaedtii, Brandt, 1833

  The salinity tolerance, hematological and hydromineral regulation capabilities of juvenile Russian sturgeon (Acipenser gueldenstaedtii) were investigated in different ages and sizes in freshwater (FW: 0.05) but differed in experimental media (p < 0.05). Signifi cant differences were observed between the levels of plasma ion concentrations in different media (p < 0.01). Plasma Na+, K+ and Ca+2 concentrations were higher than those of FW media, but lower than in CSW media (p < 0.05). Plasma Mg+2 concentrations were lower than those of FW and CSW media, but near to EW media (p < 0.05). The hematocrit mean cell volume decreased but mean cell hemoglobin concentration, osmolarity and levels of plasma cortisol were increased from FW media to CSW media (p < 0. 05). The hemoglobin concentration (Hb), the amount of hemoglobin per erythrocyte, red and white blood cells count did not change (p>0.05). However, the results showed that the above parameters in fish fingerlings did not return to initial values in the new environment and then physiological changes happened.