title: Bioenergetic trade-offs in the sea cucumber Apostichopus japonicus (Echinodermata: Holothuroidea) in response to CO2-driven ocean acidification.
abstract: Ocean acidification (OA) caused by excessive CO2 is a potential ecological threat to marine organisms. The impacts of OA on echinoderms are well-documented, but there has been a strong bias towards sea urchins, and limited information is available on sea cucumbers. This work examined the effect of medium-term (60 days) exposure to three pH levels (pH 8.06, 7.72, and 7.41, covering present and future pH variability) on the bioenergetic responses of the sea cucumber, Apostichopus japonicus, an ecologically and economically important holothurian in Asian coasts. Results showed that the measured specific growth rate linearly decreased with decreased pH, leading to a 0.42 %·day(-1) decrease at pH 7.41 compared with that at pH 8.06. The impacts of pH on physiological energetics were variable: measured energy consumption and defecation rates linearly decreased with decreased pH, whereas maintenance energy in calculated respiration and excretion were not significantly affected. No shift in energy allocation pattern was observed in A. japonicus upon exposure to pH 7.72 compared with pH 8.06. However, a significant shift in energy budget occurred upon exposure to pH 7.41, leading to decreased energy intake and increased percentage of energy that was lost in feces, thereby resulting in a significantly lowered allocation into somatic growth. These findings indicate that adult A. japonicus is resilient to the OA scenario at the end of the twenty-first century, but further acidification may negatively influence the grazing capability and growth, thereby influencing its ecological functioning as an "ecosystem engineer" and potentially harming its culture output.
authors.affiliation: National Marine Environmental Monitoring Center, State Oceanic Administration, Dalian, 116023, People's Republic of China. xtyuan@nmemc.org.cn.
authors.forename: Xiutang
authors.initials: X
authors.lastname: Yuan
authors.affiliation: National Marine Environmental Monitoring Center, State Oceanic Administration, Dalian, 116023, People's Republic of China.|Dalian Ocean University, Dalian, 116023, People's Republic of China.
authors.forename: Senlin
authors.initials: S
authors.lastname: Shao
authors.affiliation: National Marine Environmental Monitoring Center, State Oceanic Administration, Dalian, 116023, People's Republic of China.|Dalian Ocean University, Dalian, 116023, People's Republic of China.
authors.forename: Xiaolong
authors.initials: X
authors.lastname: Yang
authors.affiliation: Dalian Ocean University, Dalian, 116023, People's Republic of China.
authors.forename: Dazuo
authors.initials: D
authors.lastname: Yang
authors.affiliation: Institute of Oceanology, Chinese Academy of Science, Qingdao, 266071, People's Republic of China.
authors.forename: Qinzeng
authors.initials: Q
authors.lastname: Xu
authors.affiliation: National Marine Environmental Monitoring Center, State Oceanic Administration, Dalian, 116023, People's Republic of China.
authors.forename: Humin
authors.initials: H
authors.lastname: Zong
authors.affiliation: Institute of Oceanology, Chinese Academy of Science, Qingdao, 266071, People's Republic of China.
authors.forename: Shilin
authors.initials: S
authors.lastname: Liu
mesh_terms: D000818:Animals; D002245:Carbon Dioxide / Q000633:toxicity*; D004447:Echinodermata; D004463:Ecology; D017753:Ecosystem; D004734:Energy Metabolism; D004784:Environmental Monitoring; D006863:Hydrogen-Ion Concentration; D009792:Oceans and Seas; D012616:Sea Cucumbers; D012617:Sea Urchins; D012623:Seawater / Q000737:chemistry*; D047528:Stichopus / Q000502:physiology*; D018675:Toxicity Tests; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D014874:Water Pollutants, Chemical; D002245:Carbon Dioxide
keywords: Apostichopus japonicus; Energy budget; Feeding; Growth; Ocean acidification; Physiology; Sea cucumber