Effect of water temperature on the immune response of white shrimp Litopenaeus vannamei to Vibrio alginolyticus

White shrimp Litopenaeus vannamei held in 25x seawater at 27 8C or 28 8C were injected with TSB-grown Vibrio alginolyticus at 1 10 colony-forming units (cfu) shrimp 1 or 1 10 cfu shrimp , and then cultivated onward at water temperatures varying from 20 to 34 8C. Over 24–144 h, mortality of V. alginolyticus-injected shrimp held at 34 8C or 32 8C was significantly higher than that of shrimp held at lower temperatures. In a separate experiment, shrimp held in 25x seawater at 28 8C and then cultured onward at 20 to 32 8C were examined for immune parameters at 24–96 h. THC, phenoloxidase activity, respiratory burst, and SOD activity decreased significantly at 24 h after transfer to 32 8C. Shrimp held in 25x seawater at 27 8C and then cultured onward at 20 to 34 8C showed a significant reduction in phagocytic activity and clearance efficiency for V. alginolyticus at 24 h after transfer to 34 8C. It was concluded that transfer of shrimp from 27 or 28 8C to higher temperatures (32 and 34 8C) reduced their immune capability and decreased resistance to V. alginolyticus infection. D 2005 Elsevier B.V. All rights reserved.