ABSTRACT
Moon phases influence the molting process of shrimp, which affect other physiological processes as immune response. This study analyzed some parameters of immune response: total hemocytes counts (THC), hemolymph clotting time and superoxide anion (O2-) production, total protein concentration, superoxide dismutase activity, and the presence of Vibrio spp. in Litopenaeus vannamei at different moon phases. The highest percentage of organisms in intermolt stage was observed in the first quarter moon phase (95%). The highest THC was observed at new moon phase, which was significantly different (p < 0.05) than that observed at the third quarter phase. Hemolymph clotting time and CFU values of Vibrio spp. showed no significant difference (p > 0.05) between different moon phases. The higher (p < 0.05) mean O2- production value (0.400 ± 0.168 nmol min-1 mL-1) was determined in hepatopancreas at new moon phase. No relationship was observed between O2- and SOD activity, indicating that this antioxidant response was enough to counteract the influence of oxidative stress in L. vannamei at different moon phases.
