Effects of diel temperature fluctuations on growth, oxygen consumption and proximate body composition in the sea cucumber Apostichopus japonicus Selenka

We studied the effects of constant temperatures (12, 15, 18, 21 and 24 °C) and diel fluctuating temperatures (15 ± 2, 18 ± 2 and 21 ± 2 °C) on growth, proximate body composition and oxygen consumption of juvenile sea cucumbers (oxygen consumption was not measured at 12 and 24 °C). Growth of juveniles varied at different constant temperatures (P < 0.05) and the maximum specific growth rate (SGR) was 1.48% day− 1 at 16–18 °C. SGR was significantly decreased at 24 °C in comparison with the other four constant temperatures. Compared to the corresponding constant temperatures, growth rate increased at the fluctuating temperatures with mean temperature below the constant temperature optimum for growth (18 °C) and decreased at the fluctuating temperatures with mean temperature above 18 °C. Body crude lipid content increased with the increase in final body weight, both at the constant temperatures and fluctuating temperatures. Crude lipid contents under the fluctuating temperatures were lower than those under the corresponding constant temperatures. Under fluctuating temperatures, oxygen consumption rates increased, but not significantly, compared to those in the corresponding constant temperatures. The fluctuating temperature mode, derived from this research, could be applied to the large-scale culture of sea cucumber.