Abstract: To clarify the physiological and metabolic responses of Crassostrea sikamea under long-term starvation stress, we measured oxygen consumption rate, ammonia excretion rate and activities of lactate dehydrogenase, succinate dehydrogenase, pyruvate kinase, superoxide dismutase, alkaline phosphatase and lysozyme in hepatopancreas after long-term starvation (0-80 d) and refeeding (90-118 d). The results showed that oxygen consumption and ammonia excretion rate of C. sikamea decreased significantly under long-term starvation (P<0.01). With the prolongation of starvation, the activities of lactate dehydrogenase, succinate dehydrogenase, pyruvate kinase, superoxide dismutase, and alkaline phosphatase in C. sikamea showed a trend of fluctuating decline, while lysozyme activity showed a trend of fluctuating rise. After refeeding, oxygen consumption and ammonia excretion rate of C. sikamea significantly increased (P<0.01). Long-term starvation may damage the metabolism and immune functions of C. sikamea, and C. sikamea, and they respond to long-term starvation stress by reducing metabolic rate and metabolic enzyme activities. Our results provide a reference for the study of metabolic regulation mechanism of marine shellfish under starvation stress.

Key words: Crassostrea sikamea, starvation stress, oxygen consumption rate, ammonia excretion rate, enzymatic activity.