Coral skeleton formation rate determines resilience to acidifying oceans


Date:
January 27, 2022
Source:
University of Wisconsin-Madison
Summary:
A new study has implications for predicting coral reef survival
and developing mitigation strategies against having their bony
skeletons weakened by ocean acidification.



FULL STORY ==========================================================================
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.

"Many agencies keep putting out reports in which they say, 'Yes, coral
reefs are threatened,' with no idea what to do," says Pupa Gilbert,
a physics professor at UW-Madison and senior author of the study that
was published Jan.

17 in the Journal of the American Chemical Society. "Finding solutions
that are science-based is a priority, and having a quantitative idea
of exactly what's happening with climate change to coral reefs and
skeletons is really important." Reef-forming corals are marine animals
that produce a hard skeleton made up of the mostly insoluble crystalline material aragonite. Aragonite forms when precursors made up of a more
soluble form, amorphous calcium carbonate, are deposited onto the growing skeleton and then crystallize.



==========================================================================
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.



==========================================================================
The team has tried to automate the analysis or use machine-learning
techniques, but those methods have not worked out. Instead, Gilbert has
found that humans making decisions are the best data processors.

Gilbert did not want to base conclusions off the decision-making of just
one or two people. So she hired a group of UW-Madison undergraduates,
most of whom came from the Mercile J. Lee Scholars Program, which works
to attract and retain talented students from underrepresented groups. This
team provided a large and diverse group of decision makers.

Dubbed the Cnidarians -- from the phylum to which corals, anemones and jellyfish belong -- this group of students became integral members of
the team.

They met several times a week via Zoom, when Gilbert would assign multiple students the same dataset to process in parallel and discuss at their
next meeting.

"If multiple people come up with precisely the same solution even though
they make different decisions, that means our analysis is robust and
reliable," Gilbert says. "The Cnidarians' contributions were so useful
that 13 of them are co-authors on this study." This study was supported
by the Department of Energy (DE-FG02-07ER15899 and DE- AC02-05CHH11231),
the National Science Foundation (DMR-1603192) and the European Research
Council (755876).

========================================================================== Story Source: Materials provided by
University_of_Wisconsin-Madison. Original written by Sarah Perdue. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Connor A. Schmidt, Cayla A. Stifler, Emily L. Luffey, Benjamin I.

Fordyce, Asiya Ahmed, Gabriela Barreiro Pujol, Carolyn P. Breit,
Sydney S. Davison, Connor N. Klaus, Isaac J. Koehler, Isabelle
M. LeCloux, Celeo Matute Diaz, Catherine M. Nguyen, Virginia Quach,
Jaden S. Sengkhammee, Evan J. Walch, Max M. Xiong, Eric Tambutte',
Sylvie Tambutte', Tali Mass, Pupa U. P. A. Gilbert. 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 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/01/220127172625.htm

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