Resolving the interactions of ocean acidification and temperature on coral calcification media pH

• Published in: Coral Reefs
• Main Authors: Allison, Nicola, Cole, Catherine, Hintz, Chris, Hintz, Ken, Rae, James, Finch, Adrian
• Other Authors: Natural Environment Research Council
• Format: Article in Journal/Newspaper
• Language: English
• Published: Springer Science and Business Media LLC 2021
• Subjects: Aquatic Science; Ocean acidification
• Online Access: http://dx.doi.org/10.1007/s00338-021-02170-2; https://link.springer.com/content/pdf/10.1007/s00338-021-02170-2.pdf; https://link.springer.com/article/10.1007/s00338-021-02170-2/fulltext.html

Abstract Ocean acidification typically reduces the calcification rates of massive Porites spp. corals, but increasing seawater temperatures (below the stress and bleaching threshold) can offset this effect. Here, we use δ 11 B to reconstruct the pH of the calcification media (pH ECM ) used to precipitate the skeleton in poritid corals cultured over a range of seawater pCO 2 and at 25 °C and 28 °C. Increasing temperature had no significant effect on pH ECM at high pCO 2 although corals increased their calcification rates. pH ECM was reduced at 28 °C compared to 25 °C at low seawater pCO 2 , although calcification rates remained constant. Increasing calcification rates could reflect the positive influence of temperature on aragonite precipitation rate, an increase in calcification media saturation state or a change in the concentration/behaviour of the skeletal organic matrix. The two temperatures utilized in this study were within the seasonal range at the coral collection site and do not represent a heat stress scenario. Increasing seawater temperatures may promote calcification in some corals in the future but are unlikely to benefit the majority of corals, which are already living close to their maximum thermal tolerance limits.