White Shrimp Litopenaeus vannamei that Have Received Carrageenan via Immersion Show Protective Immunity after Salinity Stress

Abstract

White shrimp ＂Litopenaeus vannamei＂ which had been immersed in seawater (35 per mille) containing carrageenan at 0 (control) and 200 mg/l for 3 h, were subjected to salinity change (transferred to 25 per mille), and the immune parameters including hyaline cells (HCs), granular cells (GCs, including semi-granular cells), total hemocyte count (THC), phenoloxidase (PO) activity, respiratory burst (RB), superoxide dismutase (SOD) activity, hemolymph protein concentration were examined 6~96 h post-transfer. Shrimp with no exposure to carrageenan and no salinity change served as the background control. Results indicated that HC, GC, THC, PO activity, RB, SOD activity, and hemolymph protein concentration of shrimp immersed in 200 mg/l carrageenan were significantly higher than those of control shrimp at 6~12 h post-stress. Results also indicated that these parameters of shrimp immersed in 200 mg/l carrageenan had returned to the background values at 24, 24, 24, 48, 12, 48, and 12 h post-stress, whereas these immune parameters in control shrimp had returned to the original values at 96 h post-stress. It was therefore concluded that the innate immunity of shrimp which had been immersed in seawater containing the carrageenan exhibited a protective effect against low salinity change as evidenced by earlier recovery of immune parameters.