Influence of Salinity on the Survival and Growth of Juvenile Coregonus Ussuriensis Berg

To explore the suitable salinity range of Coregonus ussuriensis Berg, we investigated the effect of induced salinity change in captivity on C. ussuriensis with an initial body weight of 35 ± 1.5 g. After 30 days of salinity acclimation, the survival, growth performance, blood biochemical profiles, antioxidative capacity, and tissue structure of juveniles under four salinity conditions (8‰, 16‰, 24‰, and 32‰) were investigated. Our results revealed that serum penetration, blood glucose, and serum Na + , Cl − , and Mg 2+ gradually increased with increasing salinity until 32‰ salinity, when a significant difference was observed, whereas the K + concentration showed a downward trend. The tissue sections showed that under high salinity (32‰), the liver and gill tissues of the fish were severely damaged and the vacuolation was serious. The levels of superoxide dismutase, glutathione peroxidase, and serum cortisol gradually increased with increasing salinity. A gene expression analysis showed that the increase in salinity induced higher expression of stress-, growth-, and inflammation-related genes ( HSP70 , Gh and Igf-1 , and IL-1β , respectively). The downregulation of stress-related gene expression at 32‰ salinity may indicate that this level of salinity exceeded the regulatory capacity of C. ussuriensis . We concluded that C. ussuriensis may survive in an estuary under 0–24‰ salinity. Our findings provide insights into the physiological adaptation of C. ussuriensis to salinity change. These results could improve our knowledge of the stress response and resilience of estuarine fish to hyposalinity and hypersalinity stress.