Multidecadal decoupling between coral calcifying fluid and seawater saturation states

Area of Science:

• Marine Biology
• Oceanography
• Climate Change Science

Background:

• Ocean acidification, driven by increased atmospheric CO2, lowers seawater aragonite saturation state (ΩAr).
• Coral skeletons form from a calcifying fluid, which is supplied by seawater, making it theoretically susceptible to reduced ΩAr.

Purpose of the Study:

• To reconstruct coral calcifying fluid ΩAr over 200 years.
• To investigate coral calcifying fluid regulation and calcification response to ocean acidification.

Main Methods:

• Analysis of two Porites sp. coral skeletal cores from the Coral Sea.
• Raman spectroscopy techniques to reconstruct calcifying fluid ΩAr at monthly resolution.
• Examination of up to 200 years of skeletal growth.

Main Results:

• Coral calcifying fluid ΩAr significantly increased over the study period.
• Evidence suggests corals can regulate their calcifying fluid chemistry.
• Observed adaptation in the wild surpasses predictions from short-term laboratory experiments.

Conclusions:

• Coral calcifying fluid chemistry shows resilience to ocean acidification.
• Porites corals demonstrate a capacity to adjust to changing oceanic conditions.
• Findings challenge previous assumptions about coral vulnerability to climate change.