Corals concentrate dissolved inorganic carbon to facilitate calcification

Area of Science:

• Marine Biology
• Geochemistry
• Biomineralization

Background:

• Understanding dissolved inorganic carbon (DIC) sources for coral skeletons is crucial for biomineralization and ocean acidification impacts.
• Scleractinian coral reefs face threats from changing ocean chemistry.

Purpose of the Study:

• To investigate the DIC sources and chemistry within the coral calcification fluid.
• To understand how corals regulate their internal chemistry for skeleton formation.

Main Methods:

• Utilized skeletal boron geochemistry to reconstruct calcification fluid chemistry.
• Analyzed the concentration and speciation of DIC at the coral calcification site.

Main Results:

• Corals concentrate DIC significantly above seawater levels at the calcification site.
• Bicarbonate is a major contributor to the DIC pool used in skeleton building.
• Corals elevate calcification fluid pH, increasing carbonate ion concentration and aragonite saturation state.

Conclusions:

• Corals actively control calcification fluid chemistry to optimize skeleton precipitation.
• This internal regulation mechanism may enhance coral resilience to ocean acidification.