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

White shrimp Litopenaeus vannamei held in 25 parts per thousand seawater at 27 degrees C or 28 degrees C were injected with TSB-grown Vibrio, alginolyticus at 1x10(4) colony-forming units (cfu) shrimp(-1) or 1x10(5) cfu shrimp(-1), and then cultivated onward at water temperatures varying from 20 to 34 degrees C. Over 24-144 h, mortality of V. alginolyticus-injected shrimp held at 34 degrees C or 32 degrees C was significantly higher than that of shrimp held at lower temperatures. In a separate experiment, shrimp held in 25 parts per thousand seawater at 28 degrees C and then cultured onward at 20 to 32 degrees C 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 degrees C. Shrimp held in 25 parts per thousand seawater at 27 degrees C and then cultured onward at 20 to 34 degrees C showed a significant reduction in phagocytic activity and clearance efficiency for V. alginolyticus at 24 h after transfer to 34 degrees C. It was concluded that transfer of shrimp from 27 or 28 degrees C to higher temperatures (32 and 34 degrees C) reduced their immune capability and decreased resistance to V. alginolyticus infection. (c) 2005 Elsevier B.V. All rights reserved.