Corals concentrate dissolved inorganic carbon to facilitate calcification

Nicola Allison, Itay Cohen, Adrian A. Finch, Jonathan Erez, Alexander W. Tudhope

Research output: Contribution to journalArticlepeer-review


The sources of dissolved inorganic carbon (DIC) used to produce scleractinian coral skeletons are not understood. Yet this knowledge is essential for understanding coral biomineralization and assessing the potential impacts of ocean acidification on coral reefs. Here we use skeletal boron geochemistry to reconstruct the DIC chemistry of the fluid used for coral calcification. We show that corals concentrate DIC at the calcification site substantially above seawater values and that bicarbonate contributes a significant amount of the DIC pool used to build the skeleton. Corals actively increase the pH of the calcification fluid, decreasing the proportion of DIC present as CO2 and creating a diffusion gradient favouring the transport of molecular CO2 from the overlying coral tissue into the calcification site. Coupling the increases in calcification fluid pH and [DIC] yields high calcification fluid [CO32−] and induces high aragonite saturation states, favourable to the precipitation of the skeleton.
Original languageEnglish
Pages (from-to)5741
JournalNature Communications
Publication statusPublished - 22 Dec 2014


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