Effects of water salinity on the growth, ovarian development, osmoregulation, metabolism and antioxidant capacity of adult female swimming crab(Portunus trituberculatus)

In order to investigate the effects of long-term salinity adaptation on growth, ovarian development, osmoregulation, metabolism and antioxidant capacity of adult female swimming crab (Portunus trituberculatus), adult female P. trituberculatus post puberty molt was subjected to four water salinities (10, 15, 20 and 25) for 60 days. The results showed as follows: The survival rate, weight gain rate, specific growth rate and gonadosomatic index of female crabs increased significantly with increasing water salinity. The serum osmolality and the contents of Na⁺, Cl^-, Ca²⁺, Mg²⁺ and major free amino acids, and total free amino acids in the serum, as well as the posterior gills Na⁺/K⁺-ATPase activity showed an overall increasing trend with increasing water salinity. The contents of serum glucose and hepatopancreas lactic acid decreased significantly with increasing water salinity, while the levels of serum urea nitrogen, uric acid, and hepatopancreas uric acid showed an increasing trend. The higher contents of triglyceride, total cholesterol and urea nitrogen in the hepatopancreas were detected in 20 and 25 salinity treatments. The activity of total superoxide dismutase in the serum and hepatopancreas of females from 10 salinity treatment was significantly lower than that of other salinity treatments, while the highest levels of total antioxidant capacity, glutathione peroxidase, γ-glutamyl transpeptidase and hemocyanin in the serum, as well as and hepatopancreas glutathione peroxidase and malondialdehyde were detected at 10 salinity treatment. In conclusion, elevating water salinity could promote the growth and ovarian development of adult female P. trituberculatus, and the females had lower levels of metabolism and oxidative stress under the conditions of 20 and 25 salinities.