Researchers have studied the hard skeletons of coral reefs to better predict their survival. Vulnerable to ocean acidification caused by global warming, corals are among the most threatened underwater species.
Corals that inhabit the ocean floor are particularly vulnerable to global warming. They are particularly vulnerable to ocean acidification, brought about by atmospheric CO2 emissions generated by human activity, which increases the ocean temperature and accelerates coral bleaching.
Researchers at the University of Wisconsin-Madison (USA) have attempted to predict the resilience of coral reefs by studying their hard, bony skeletons. Composed of aragonite, coral skeletons form when precursors made up of a more soluble form -- amorphous calcium carbonate -- are deposited onto the skeleton then crystallize. The research team studied three genera of coral, examining the components of their growing skeletons in depth.
According to the research, published in the Journal of the American Chemical Society, the crystallization rate of coral skeletons differs across species and is correlated with their resilience to acidification. The thicker the band of uncrystallized minerals, the slower the crystallization process, the study notes.
Acropora corals, for example, are more sensitive to acidification and have a much thicker band of amorphous calcium carbonate than Stylophora type corals. Turbinaria corals have an even thinner layer than the Stylophora, suggesting that they are even more resistant to the phenomenon of ocean acidification.
"If the surface of the coral skeleton, where all this amorphous calcium carbonate is being deposited by the living animal, crystallizes quickly, then that particular species is resilient to ocean acidification; if it crystallizes slowly, then it's vulnerable," concludes Pupa Gilbert, a physics professor at UW-Madison and senior author of the study.
Although corals represent less than 1% of the seabed, they constitute ecosystems that are among the richest in biodiversity on the planet, with more than one million species estimated to be associated with reefs. Their protection is therefore essential.
