Effects of ammonia nitrogen stress on activities of non-specific immune enzymes of sea cucumber Luhai No. 1.

[Objective] This study explored the adaptability of a new variety of sea cucumber (Apostichopus japonicus) to changes of ammonia nitrogen in environment. [Method] The weights of sea cucumbers were (30. 2 ± 0. 2) g/ind and (59. 2 ± 0. 8) g/ind and the concentrations of ammonia nitrogen were 0, 2, 4, 6, 8 and 10 mg/L. The survival and growth of sea cucumbers and changes in activities of four non-specific immune enzymes (SOD, CAT, ACP and AKP) in coelomic fluid were studied. [Result] Ammonia nitrogen stress had significant effects on survival rate and growth of sea cucumber Luhai No. 1. When the concentration of ammonia nitrogen was 10 mg/L, both groups showed excreted internal organs, melted skin and death. The sea cucumbers in group A with 10 mg/L ammonia nitrogen had the lowest survival rate of 87. 2%. Body weight and specific growth rate (SGR) of sea cucumbers decreased with the increase of ammonia nitrogen concentration. The SGR of 4,6,8 and 10 mg/L ammonia nitrogen groups was significantly lower than that of the control group (P<0. 05). With the increase of exposure time, activities of SOD, CAT, ACP and AKP of sea cucumbers at different concentrations of ammonia nitrogen increased first and then decreased. On the 5th day of ammonia nitrogen stress, activities of SOD and CAT in some experimental groups with 2 and 4 mg/L ammonia nitrogen reached peaks. On the 15th day of ammonia nitrogen stress, activities of SOD, CAT, ACP and AKP in groups with 8 and 10 mg/L ammonia nitrogen were lower than those in the control group, and most of them showed significant differences (P<0. 05). [Conclusion] The concentration of ammonia nitrogen in aquaculture environment should be controlled below 6 mg/L to reduce adverse effects on sea cucumber Luhai No. 1. [ABSTRACT FROM AUTHOR]