Full in vivo characterization of carbonate chemistry at the site of calcification in corals

Sevilgen, Duygu S.; Venn, Alexander A.; Hu, Marian Yong-An; Tambutté, Éric; Beer, Dirk de; Planas‐Bielsa, Víctor; Tambutté, Sylvie

doi:10.1126/sciadv.aau7447

Cited by 91 publications

(147 citation statements)

References 52 publications

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“…Although the excess free energy of high surface area porous materials could provide a thermodynamic driving force for porosity reduction by ions, this is very slow at biologically , as expressed by the saturation state of the solution with respect to aragonite, Ω arag , would provide a driving force both for diffusive transport into the porous biomineral and for ion attachment, leading to aragonite growth, gradual porosity loss, and eventually space-filling. Such high-supersaturation solution has indeed been previously observed in living corals as they form skeletons, is termed CF (42), and its chemical composition was recently measured in vivo (26). Based on those measurements, Ω arag can be calculated using the formula:…”

Section: Resultsmentioning

confidence: 93%

From particle attachment to space-filling coral skeletons

Sun

Stifler

Chopdekar

et al. 2020

Proc. Natl. Acad. Sci. U.S.A.

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Reef-building corals and their aragonite (CaCO3) skeletons support entire reef ecosystems, yet their formation mechanism is poorly understood. Here we used synchrotron spectromicroscopy to observe the nanoscale mineralogy of fresh, forming skeletons from six species spanning all reef-forming coral morphologies: Branching, encrusting, massive, and table. In all species, hydrated and anhydrous amorphous calcium carbonate nanoparticles were precursors for skeletal growth, as previously observed in a single species. The amorphous precursors here were observed in tissue, between tissue and skeleton, and at growth fronts of the skeleton, within a low-density nano- or microporous layer varying in thickness from 7 to 20 µm. Brunauer-Emmett-Teller measurements, however, indicated that the mature skeletons at the microscale were space-filling, comparable to single crystals of geologic aragonite. Nanoparticles alone can never fill space completely, thus ion-by-ion filling must be invoked to fill interstitial pores. Such ion-by-ion diffusion and attachment may occur from the supersaturated calcifying fluid known to exist in corals, or from a dense liquid precursor, observed in synthetic systems but never in biogenic ones. Concomitant particle attachment and ion-by-ion filling was previously observed in synthetic calcite rhombohedra, but never in aragonite pseudohexagonal prisms, synthetic or biogenic, as observed here. Models for biomineral growth, isotope incorporation, and coral skeletons’ resilience to ocean warming and acidification must take into account the dual formation mechanism, including particle attachment and ion-by-ion space filling.

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Section: Resultsmentioning

confidence: 93%

From particle attachment to space-filling coral skeletons

Sun

Stifler

Chopdekar

et al. 2020

Proc. Natl. Acad. Sci. U.S.A.

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“…Despite Ωaragonite being a good predictor for biological calcification especially at fully marine conditions, there is little evidence supporting its mechanistic role in biocalcification. Even with a rudimentary understanding of calcification mechanisms in molluscs, we know that increased [H + ] inhibits extracellular calcification by increasing the proton gradient between the calcifying fluid and seawater (Ramesh, et al, 2017;Sevilgen, et al, 2019). Additionally, since HCO3is likely the primary carbon species used in calcification (see previous paragraph) and its availability stimulates CaCO3 biomineralisation, a more accurate and mechanistically relevant predictor for biocalcification is the substrate (HCO3 -) inhibitor (H + ) ratio or SIR (Jokiel, et al, 2013;Bach, 2015;Thomsen, et al, 2015;Cyronak, et al, 2016,).…”

Section: Introductionmentioning

confidence: 99%

Decoupling salinity and carbonate chemistry: Low calcium ion concentration rather than salinity limits calcification in Baltic Sea mussels

Sanders¹,

Thomsen²,

Müller³

et al. 2020

Preprint

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“…Corals cultured at 750 µatm pCO 2 have higher skeletal [Asx] compared to their genotype analogues cultured at 180 µatm and 400 µatm (by 99% and 61% respectively). ECM Ω in the branching coral Stylophora pistillata cultured at 400 µatm and 25 °C is ~ 12 39 . At this Ω, raising seawater [aspartic acid] from 0.1 to 0.4 mM (our current best estimate of the ECM concentration in corals cultured at 180 and 750 µatm respectively) increases the biomolecule inhibition of aragonite precipitation from ~ 3 to ~ 11% (Fig.…”

Section: Resultsmentioning

confidence: 99%

The role of aspartic acid in reducing coral calcification under ocean acidification conditions

Kellock

Cole

Penkman

et al. 2020

Sci Rep

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Biomolecules play key roles in regulating the precipitation of CaCO 3 biominerals but their response to ocean acidification is poorly understood. We analysed the skeletal intracrystalline amino acids of massive, tropical Porites spp. corals cultured over different seawater pCO 2. We find that concentrations of total amino acids, aspartic acid/asparagine (Asx), glutamic acid/glutamine and alanine are positively correlated with seawater pCO 2 and inversely correlated with seawater pH. Almost all variance in calcification rates between corals can be explained by changes in the skeletal total amino acid, Asx, serine and alanine concentrations combined with the calcification media pH (a likely indicator of the dissolved inorganic carbon available to support calcification). We show that aspartic acid inhibits aragonite precipitation from seawater in vitro, at the pH, saturation state and approximate aspartic acid concentrations inferred to occur at the coral calcification site. Reducing seawater saturation state and increasing [aspartic acid], as occurs in some corals at high pCO 2 , both serve to increase the degree of inhibition, indicating that biomolecules may contribute to reduced coral calcification rates under ocean acidification.

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Full in vivo characterization of carbonate chemistry at the site of calcification in corals

Abstract: In vivo measurements of [Ca2+] and [CO32−] indicate biological control of carbonate chemistry at site of calcification in corals.

Cited by 91 publications

References 52 publications

From particle attachment to space-filling coral skeletons

From particle attachment to space-filling coral skeletons

Decoupling salinity and carbonate chemistry: Low calcium ion concentration rather than salinity limits calcification in Baltic Sea mussels

The role of aspartic acid in reducing coral calcification under ocean acidification conditions

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