Responses of calcification of massive and encrusting corals to past, present, and near-future ocean carbon dioxide concentrations

Highlights: • Growth rates of two corals in the acidified seawater were evaluated. • Highest growth rates were observed in pre-industrial pCO₂ level. • The growth rates also decreased in the near-future ocean acidification level. • The growth responses were affected by variations of parameters of carbon chemistry. • Bayesian modeling approach was effective for the inference of the best model. - Abstract: In this study, we report the acidification impact mimicking the pre-industrial, the present, and near-future oceans on calcification of two coral species (Porites australiensis, Isopora palifera) by using precise pCO₂ control system which can produce acidified seawater under stable pCO₂ values with low variations. In the analyses, we performed Bayesian modeling approaches incorporating the variations of pCO₂ and compared the results between our modeling approach and classical statistical one. The results showed highest calcification rates in pre-industrial pCO₂ level and gradual decreases of calcification in the near-future ocean acidification level, which suggests that ongoing and near-future ocean acidification would negatively impact coral calcification. In addition, it was expected that the variations of parameters of carbon chemistry may affect the inference of the best model on calcification responses to these parameters between Bayesian modeling approach and classical statistical one even under stable pCO₂ values with low variations