Oceans have continuously absorbed anthropogenic carbon dioxide from the atmosphere. The early life stages are likely vulnerable to low pH conditions. The present study aimed to assess the anemonefish (Amphiprionsebae), egg hatch rate and gonadal tissue condition in different pH levels in 6 weeks. Seawater pH was manually manipulated by bubbling known concentrations of CO2 to achieve three pH treatments 8.1, 7.7 and 7.3. Egg hatch rate decreased with declining pH (ambient pH – 93 %, pH 7.7 – 92 %, pH 7.3 – 88 %) and a slight time delay was observed between the ambient and lower pH treatments. The condition of testicular and ovarian tissue was not affected by low pH levels. Overall, present experiment found that the slight negative effects on egg hatching success in low pH condition. The experimental results suggested that early life stages expected to vulnerable to near future ocean acidification.

In order to allow full comparability with other ocean acidification data sets, the R package seacarb (Gattuso et al, 2019) was used to compute a complete and consistent set of carbonate system variables, as described by Nisumaa et al. (2010). In this dataset the original values were archived in addition with the recalculated parameters (see related PI). The date of carbonate chemistry calculation by seacarb is 2020-07-07.