A new University of Wisconsin-Madison study has implications for predicting coral reef survival and developing mitigation strategies against having their bony skeletons weakened by ocean acidification.
Though coral reefs make up less than one percent of the ocean floor, these ecosystems are among the most biodiverse on the planet — with over a million species estimated to be associated with reefs.
The coral species that make up these reefs are known to be differently sensitive or resilient to ocean acidification — the result of increasing atmospheric carbon dioxide levels. But scientists are not sure why.
In the study, researchers show that the crystallization rate of coral skeletons differs across species and is correlated with their resilience to acidification.
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The team studied three genera of coral and took an in-depth look at the components of their growing skeletons. They used a technique that Gilbert pioneered called PEEM spectromicroscopy, which detects the different forms of calcium carbonate with the greatest sensitivity to date.
When they used these spectromicroscopy images to compare the thickness of amorphous precursors to the crystalline form, they found that Acropora, which is more sensitive to acidification, had a much thicker band of amorphous calcium carbonate than Stylophora, which is less sensitive.
A third genus of unknown sensitivity, Turbinaria, had an even thinner amorphous precursor layer than Stylophora, suggesting it should be the most resilient of the three to ocean acidification.
The thicker the band of uncrystallized minerals, the slower the crystallization process.
“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,” Gilbert says. “For once, it’s a really simple mechanism.”
The mechanism may have worked out to be simple, but the data analysis required to process and interpret the PEEM images is anything but. Each pixel of imaging data acquired has a calcium spectrum that needs to be analyzed, which results in millions of data points. Processing the data includes many decision-making points, plus massive computing power.
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Journal Reference:
Faster Crystallization during Coral Skeleton Formation Correlates with Resilience to Ocean Acidification. Journal of the American Chemical Society, 2022; 144 (3): 1332 DOI: 10.1021/jacs.1c11434
University of Wisconsin-Madison (via ScienceDaily), 27 January 2022. Press release.
