Effects of salinity and dissolved oxygen variation on the non-specific immune response of Apostichopus japonicus

An experiment was conducted to evaluate the effect of different level of salinity stress(20,25,35,40and 30)and different dissolved oxygen concentration(DO 2-5mg/L,7-9mg/L,and 15-20mg/L)on activity of non-specific immunity enzymes such as acid phosphatase(ACP),alkaline phosphatase(AKP),superoxide dismutase(SOD),and lysozyme(LSZ)of seacucumber Apostichopus japonicus.The activity of ACP,AKP,and LZM increased and the activity of SOD decreased under acute salinity change.On the 10th day,the activity of non-specific immunity enzymes were highly influenced.The over-saturated oxygen treatment(DO 15-20 mg/L)maintained high activity level of ACP,AKP,LZM and SOD.The activity of ACP, AKP and LZM increased only on the 10th day in lower dissolved oxygen treatment(DO 2-5mg/ L).Activities of all the tested non-specific immunity enzymes in the experimental treatments recovered the initial level except the activity of AKP and SOD under the low salinity(20)stress. The results indicate that low salinity stress has a great effect on the immunity of sea cucumber. The AKP activity in over-saturated oxygen treatment were significantly higher than the control(DO 7-9mg/L),indicating that high dissolved oxygen concentration improves the immunity of sea cucumber to some extent.