Change in water temperature on the immune response of Taiwan abalone Haliotis diversicolor supertexta and its susceptibility to Vibrio parahaemolyticus

Taiwan abalones, Haliotis diversicolor supertexta, held in 30%. seawater at 28 degreesC, were injected with TSB-grown Vibrio parahaemolyticus (1.6 X 10(5) cfu abalone(-1)) and then transferred to 20, 24, 28 and 32 degreesC. All abalones transferred to 32 degreesC died by 72 h. The mortality of V. parahaemolyticus-injected abalone held at 20 and 24 degreesC was significantly lower over 24-96 h, compared to animals held at 28 and 32 degreesC. In a separate experiment designed to measure immune function, abalones held in 30parts per thousand seawater at 28 degreesC and then transferred to 20, 24, 28 and 32 degreesC were examined for total haemocyte count, phenoloxidase activity, respiratory burst, and phagocytic activity to V. parahaemolyticus after 24, 72 and 120 h. The phenoloxidase activity and phagocytic activity decreased significantly, whereas respiratory burst increased significantly in abalone transferred to 32 degreesC. It is concluded that transfer of abalone from 28 degreesC to 32 degreesC reduced their innate immunity and resistance against V. parahaemolyticus infection. (C) 2004 Elsevier Ltd. All rights reserved.