GROWTH AND BIOENERGETICS OF THE SEA CUCUMBER APOSTICHOPUS JAPONICUS (ECHINODERMATA: HOLOTHUROIDEA) IN RESPONSE TO SEAWATER ACIDIFICATION AND WARMING

In recent years, threat to nearshore marine ecosystems and marine organisms caused by seawater acidification and seawater warming are becoming increasingly serious. In order to study the effects of CO₂-driven ocean acidification and warming on growth and energy budget of the sea cucumber Apostichopus japonicus, which is a key species in the coastal ecosystem of East Asia, four experimental treatments were set up, namely, control (seawater temperature of the Dalian coast, pCO₂ 400 µatm), ocean warming (OW, seawater temperature of the Dalian coast plus 3℃, pCO₂ 400 µatm), ocean acidification (OA, seawater temperature of the Dalian coast, pCO₂ 1100 µatm) and Ocean acidification and warming (OAW, seawater temperature of the Dalian coast plus 3℃, pCO₂ 1100 µatm). The result showed that A. japonicus in OW were not significantly affected in contrast to control. However, the specific growth rate (SGR) of A. japonicus in OA was the lowest, which decreased by 0.19%/d compared with the control treatment, and the body weight Coefficient variations of A. japonicus in OA was the largest. The final body weight and SGR of A. japonicus in OAW showed no significantly difference with those in control, bur ingestion rate and feces production rate were both significantly higher than those in the control. The bioenergetic pattern of A. japonicus in OW and OA did not change significantly compared with that in the control, but it changed significantly in OAW, with the percentage of the FCE being significantly higher than the other three treatments. Our study suggests that seawater acidification inhibited the growth of A. japonicus versus change its energy distribution pattern. The decrease of growth in OA mainly depended on the decrease of food ingestion. The combined effect of seawater acidification and rising temperature may compensate for the negative effect of seawater acidification on growth by changing the energy distribution pattern of A. japonicus.