Effects of acute low salinity stress on the liver structure, physiology and biochemistry of juvenile Chinese sea bass (Lateolabrax maculatus)

Abstract

In order to explore the effects of acute low salinity stress on the liver structure, physiology and biochemistry of the larvae of Lateolabrax maculatus, the experiment was carried out to transfer the juveniles direct from salinity 30‰ (control group) to salinity 20‰, 10‰, and 0‰, respectively. Changes in liver microstructure and related physiological and biochemical indexes at different time points were observed. The results showed that no fish died during the whole experiment and all of them returned to normal behavior within 15 minutes. The liver cells of juvenile Chinese sea bass showed pathological changes such as swelling, vacuolation and nuclear pyknosis after low salinity stress, and the lower the salinity, the earlier the abnormal phenomenon appeared. The total antioxidant capacity (T-AOC) and superoxide dismutase (SOD) of liver showed a rapid increase and then decrease; The level of malondialdehyde (MDA) returned to normal after high fluctuations. The activity of lysozyme (LZM) in experimental groups were higher than that in control group between 12h and 48h, while there was not significantly different before 6h in each group (P>0.05), all of them returned to normal in 96 h. The activity of alkaline phosphatase (ALP) and acid phosphatase (ACP) increased firstly and then decreased during the time of stress, and there was no significant difference between each group at the same time point (P>0.05). The comprehensive analysis showed that the juvenile Chinese sea bass had strong osmotic pressure regulation ability, and the acute low salinity stress had little effect on the liver structure and physiological and biochemical indexes.