Bath administration of carrageenan produces protective immunity of white shrimp Litopenaeus vannamei in response to ammonia stress

Abstract

White shrimp Litopenaeus vannamei immersed in seawater containing carrageenan at 0 (control), 200, and 400 mg/l for 3 h, were exposed to 5 mg/l ammonia-N (ammonia-N), and immune parameters including hyaline cell (HC), granular cell (GC, including semi-granular cell), the total hemocyte count (THC), phenoloxidase (PO) activity, respiratory burst (RB), superoxide dismutase (SOD) activity, lysozyme activity, and hemolymph protein level were examined 24~144 h post-stress. Shrimp immersed in seawater with no ammonia stress served as the background control. Results indicated that HC, THC, PO, RB and SOD activity of shrimp immersed in 400 mg/l carrageenan were significantly higher than those of control shrimp at 24~48 h post-stress. Results indicated that the RB, SOD activity, lysozyme activity and hemolymph protein level of shrimp immersed in 400 mg/l carrageenan had returned to the background values at 144, 144, 120, and 144 h post-stress, whereas these values of control shrimp remained lower than those of background values at 144 h post-stress. It was therefore concluded that white shrimp immersed in seawater containing 400 mg/l carrageenan exhibited a protective effect against ammonia stress as evidenced by less decrease of immune parameters, compared to background values. Shrimp subjected to ammonia stress showed a greater decrease in PO activity and less decreases in RB and SOD activity indicating progressive perturbation of the humoral immunity.