Effects of aestivation on the energy budget of sea cucumber Apostichopus japonicus (Selenka) (Echinodermata: Holothuroidea)

Apostichopus japonicus is a kind of temperate sea cucumbers, known to aestivate when water temperature rises above 20°C to 24.5°C. In this study, we measured the effects of aestivation on the energy utilization (i.e., energy allocation in growth, feces discharge, respiration and excretion) of A. japonicus with two different body weights (134.0 g ± 3.5 g and 73.6 g ± 2.2 g) at water temperature from 10°C to 30°C with an interval of 5°C. Noticeable variation in the energy utilization of sea cucumbers was observed in this study. During the non-aestivation period, energy deposit in growth was lower and the energy loss in feces accounted for the majority of the feeding energy. Under the threshold temperature, the feeding energy reduced and the proportion of energy deposit in growth became negative. During aestivation, sea cucumbers discontinued feeding energy, resulting in weight loss. Our study suggested that the ecological implication of aestivation in this species could lead to a model of energy saving during the long-term hot period.