Effect of high temperature on survival, oxygen consumption, behavior, ammonia-N excretion, and related immune indicators of the Japanese scallop Mizuhopecten yessoensis

Abstract

In this study, two experiments were conducted to test the effect of high temperature on survival, behavior, oxygen consumption, ammonia-N excretion, and enzyme activities related to oxidative stress of the Japanese scallop Mizuhopecten yessoensis. In the first test, we abruptly transferred scallops from the rearing temperature (15 °C, control temperature) to 20, 22, 24, and 26 °C. Scallops exposed to 26 °C were significantly affected by temperature, with 100 % mortality after 12 h. The 8-, 12-, 24-, 48-, and 96-h lethal temperatures for 50 % mortality (LT50) were 27.5, 24.4, 24.3, 24.2, and 23.8 °C, respectively. The activities of CAT and SOD and the T-AOC in the coelomic fluid of M. yessoensis changed significantly after high-temperature stress (P < 0.05). They reached to the highest levels after 8 h of stress in the 22, 24, and 26 °C treatment groups then returned to the control group level. The content of MDA reached the highest level after 12 h in each temperature treatment. In the second test, scallops were acclimatized to the different temperature levels (20, 22, 24, and 26 °C) and then maintained for 30 days. Survival was significantly lower at 26 °C than at the other temperatures, and the highest survival occurred in the 15 °C treatment. High temperature also significantly influenced the oxygen consumption rates and ammonia-N excretion rates (P < 0.05). As the temperature increased, the CAT and SOD activities and the T-AOC in the coelomic fluid of M. yessoensis declined significantly, whereas the MDA content increased. These results illustrate that high temperature can significantly affect the survival, behavior, oxygen consumption, ammonia-N excretion, and enzyme activities related to oxidative stress of M. yessoensis.