Influence of water temperature on physiological performance of the sea cucumber Holothuria moebii

We conducted a laboratory investigation of the influence of water temperature on the physiological performance—including faecal production, oxygen consumption, and ammonia excretion rates—of the sea cucumber Holothuria moebii. Adult H. moebii (34.39 ± 5.17 g, wet weight) were exposed to four experimental temperatures (15, 20, 25, and 30°C), which represented the temperature range in their natural habitat. Results showed that the maximum faecal production rate was observed at 30°C (71.06 ± 7.21 mg g−1 day−1), which was significantly higher than at other temperatures. This indicated that, at a high temperature, H. moebii could take in more energy than at lower temperatures. The oxygen consumption rate increased with water temperature, and the minimum value observed at 15°C (5.68 ± 0.86 µg O2 g−1 hr−1) was significantly lower than at other temperatures. The low oxygen consumption rate at 15°C indicated a low level of energy production by H. moebii during winter. The maximum ammonia excretion rate observed at 30°C (0.029 ± 0.007 µmol g−1 hr−1) was significantly higher than at other temperatures, and the positive effect of water temperature on nitrogen catabolism indicated the possibility of H. moebii being in a better nutritional status during the hot season. The minimum value of O/N ratio at 15°C (25.55 ± 4.70) indicated the mixed utilization of protein- and carbon-based substrates during winter, while the high value of O/N ratios in other treatments (all >32) indicated the dominance of carbohydrate and/or lipid metabolism in warm and hot seasons. The results of this study suggest that H. moebii is more suitable for rearing in warm waters (>20°C).