[Coral-List] Biological control of aragonite precipitation in stony corals

[Douglas Fenner]

Building coral skeletons

Among other things, corals are threatened by ocean acidification and
warming. Being able to project the magnitude of these threats requires an
understanding of how corals form their carbonate skeletons. Von Euw
*et al.* combined
ultrahigh-resolution three-dimensional imaging and two-dimensional
solid-state nuclear magnetic resonance spectroscopy to study coral
skeletons. They found that mineral precipitation in corals is a
biologically controlled process mediated by organic molecules, rather than
an abiotic one that depends only on physico-chemical conditions. This has
important implications for the health of corals in our warmer, higher-CO2
 future.
Abstract

Little is known about how stony corals build their calcareous skeletons.
There are two prevailing hypotheses: that it is a physicochemically
dominated process and that it is a biologically mediated one. Using a
combination of ultrahigh-resolution three*-*dimensional imaging and
two-dimensional solid-state nuclear magnetic resonance (NMR) spectroscopy,
we show that mineral deposition is biologically driven. Randomly arranged,
amorphous nanoparticles are initially deposited in microenvironments
enriched in organic material; they then aggregate and form ordered
aragonitic structures through crystal growth by particle attachment. Our
NMR results are consistent with heterogeneous nucleation of the solid
mineral phase driven by coral acid-rich proteins. Such a mechanism suggests
that stony corals may be able to sustain calcification even under lower pH
conditions that do not favor the inorganic precipitation of aragonite.

http://science.sciencemag.org/content/356/6341/933/tab-pdf

Not open-access.  Click on "see all authors and affiliations" and look for
corresponding author email.

Cheers,  Doug


-- 
Douglas Fenner
Contractor for NOAA NMFS Protected Species, and consultant
"have regulator, will travel"
PO Box 7390
Pago Pago, American Samoa 96799  USA

phone 1 684 622-7084

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http://chagosinformationportal.org/corals

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http://www.sciencemag.org/news/2017/05/goodbye-smokestacks-startup-invents-zero-emission-fossil-fuel-power?utm_campaign=news_daily_2017-05-24&et_rid=17045989&et_cid=1345339

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http://science.sciencemag.org/content/355/6331/1269?utm_campaign=toc_sci-mag_2017-03-23&et_rid=17045989&et_cid=1233226