Feeding, metabolism and growth in response to temperature in juveniles of the Australasian sea cucumber, Australostichopus mollis

In the present study the importance of seawater temperature for the food intake, food utilization and growth of aquacultured juveniles of the Australasian sea cucumber, Australostichopus mollis, was examined. The juveniles (16.5 ± 0.5 g, wet weight) were experimentally exposed to four seawater temperatures (15, 18, 21, and 24 °C) for 105 days, during which they were fed mussel waste, a highly effective natural food source, that is utilised by sea cucumbers under co-culture conditions beneath mussel farms. At each temperature treatment the feeding, metabolism, growth and survival of the juveniles were evaluated. Overall, the sea cucumbers responded negatively to an increase of temperature from 15 to 21 °C with decreased food intake, and growth rates, and elevated metabolism. The survival of juveniles was compromised when held at 24 °C. Most importantly, the food conversion efficiency of juveniles at 15 °C was over seven times greater than for those growing at 21 °C which was reflected in the growth rates (i.e., 0.71 ± 0.05% d− 1 versus 0.28 ± 0.05% d− 1). The results of this study suggest that consideration of ambient temperature regimes will be a critical factor for the selection of suitable aquaculture locations for A. mollis due to the risk of mortality at higher temperatures (≥ 24 °C) and markedly improved growth and food utilization at lower temperatures around 15 °C.

► The response to different temperatures of juvenile sea cucumbers was evaluated. ► During experimentation the juveniles were fed mussel waste. ► Temperature affected metabolism, ingestion, food conversion efficiency and growth. ► The implications for out-growing juveniles of this species are discussed.