Impact of CO2-driven acidification on the development of the sea cucumber Apostichopus japonicus (Selenka) (Echinodermata: Holothuroidea)

• First observation on holothurian early development responded to OA.
• A device is designed for hatching embryos and larvae in OA research.
• The impact of pH on developmental time is stage dependent.
• No significant effect of pH on the auricularia growth rate.
• The early life stage of A. japonicus is resilient to OA.

We evaluated the impact of ocean acidification on the early development of sea cucumber Apostichopus japonicus. The effect of pH-levels (pH 8.04, 7.85, 7.70 and 7.42) were tested on post-fertilization success, developmental (stage duration) and growth rates. Post-fertilization success decreased linearly with pH leading to a 6% decrease at pH 7.42 as compared to pH 8.1. The impact of pH on developmental time was stage-dependent: (1) stage duration increased linearly with decreasing pH in early-auricularia stage; (2) decreased linearly with decreasing pH in the mid-auricularia stage; but (3) pH decline had no effect on the late-auricularia stage. At the end of the experiment, the size of doliolaria larvae linearly increased with decreasing pH. In conclusion, a 0.62 unit decrease in pH had relatively small effects on A. japonicus early life-history compared to other echinoderms, leading to a maximum of 6% decrease in post-fertilization success and subtle effects on growth and development.