Coral calcifying fluid aragonite saturation states derived from Raman spectroscopy

DeCarlo, Thomas M.; D’Olivo, Juan Pablo; Foster, Taryn; Holcomb, Michael; Becker, Thomas; McCulloch, Malcolm T.

doi:10.5194/bg-14-5253-2017

Cited by 57 publications

(65 citation statements)

References 91 publications

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“…We concentrated our study on JCp-1 and the abiogenic samples that were repeatedly analyzed in DeCarlo et al (2017): samples f02, f03, f06, g07, g13, and h09, which span a range of fluid Ar from 10 to 30. We then annealed a subset of JCp-1 and the abiogenic samples f03 and f06 following the procedure of Pokroy et al (2004).…”

Section: Annealing Experimentsmentioning

confidence: 99%

“…In addition to the measurements described above with the 532 nm laser, the annealed samples were also analyzed before and after heating with the same Raman instrument but with a 785 nm laser and 1,200 mm −1 grating as described in DeCarlo et al (2017). These measurements with the 785 nm laser were conducted to evaluate any changes in crystal disorder due to the annealing process.…”

Section: Raman 785 Nm Measurementsmentioning

confidence: 99%

“…The first was made with the 785 nm laser at 1 µm resolution using 0.3 s integrations. We used the 785 nm data to calculate the Ar at each 1 µm spot based on the calibration between ν 1 peak width and Ar reported in DeCarlo et al (2017). This calibration is based on the strong relationship observed between the fluid Ar of the abiogenic aragonite experiments and the aragonite lattice disorder as represented by the ν 1 peak width.…”

Section: Pocillopora Skeletal Mappingmentioning

confidence: 99%

“…Peak wavenumber reflects the average C-O bond length, which could change if the aragonite unit cell contracts or expands (Bischoff et al, 1985;Urmos et al, 1991). Although both wavenumber and FWHM could be influenced by Mg content, the relatively small concentrations of Mg in aragonite, compared to high-Mg calcite, make the role of Mg minor or negligible (Bischoff et al, 1985;Pauly et al, 2015;DeCarlo et al, 2017). We used two-sample t-tests to investigate whether ν 1 wavenumber and FWHM significantly changed after the annealing procedure.…”

Section: Data Treatment Of Raman Spectramentioning

confidence: 99%

“…Techniques for observing and mapping the distribution of the SOM include scanning electron microscopy (Clode and Marshall, 2002), helium ion microscopy (Von Euw et al, 2017), transmission electron microscopy (Benzerara et al, 2011;Falini et al, 2013), and fluorescence as detected by a Raman spectrometer (Jolivet et al, 2008;Nehrke et al, 2011;Wall and Nehrke, 2012;Von Euw et al, 2017). Of these, Raman spectroscopy is advantageous in that it can potentially identify certain organic bonds, and the same spectra provide information regarding the chemical composition of the aragonite crystals (Bischoff et al, 1985;Nehrke et al, 2011;Wall and Nehrke, 2012;DeCarlo et al, 2017;Von Euw et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

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The Origin and Role of Organic Matrix in Coral Calcification: Insights From Comparing Coral Skeleton and Abiogenic Aragonite

DeCarlo¹,

Ren²,

Farfán³

2018

Front. Mar. Sci.

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Understanding the mechanisms of coral calcification is critical for accurately projecting coral reef futures under ocean acidification and warming. Recent suggestions that calcification is primarily controlled by organic molecules and the biological activity of the coral polyp imply that ocean acidification may not affect skeletal accretion. The basis for these suggestions relies heavily on correlating the presence of organic matter with the orientation and disorder of aragonite crystals in the skeleton, carrying the assumption that organic matter observed in the skeleton was produced by the polyp to control calcification. Here we use Raman spectroscopy to test whether there are differences in organic matter content between coral skeleton and abiogenic aragonites precipitated from seawater, both before and after thermal annealing (heating). We measured the background fluorescence and intensity of C-H bonding signals in the Raman spectra, which are commonly attributed to coral polyp-derived skeletal organic matrix (SOM) and have been used to map its distribution. Surprisingly, we found no differences in either fluorescence or C-H bonding between abiogenic aragonite and coral skeleton. Annealing reduced the molecular disorder in coral skeleton, potentially due to removal of organic matter, but the same effect was also observed in the abiogenic aragonites. The presence of organic molecules in the abiogenic aragonites is further supported by measurements of N content and δ 15 N. Together, our data suggest that some of what has been interpreted in previous studies as polyp-derived SOM may actually be seawater-sourced organic matter or some other signal not unique to biogenic aragonite. Finally, we create a high-resolution Raman map of a Pocillopora skeleton to demonstrate how patterns of fluorescence and elevated calcifying fluid aragonite saturation state ( Ar ) along centers of calcification are consistent with both biological and physico-chemical controls. Our aim is to advance discussion on biological mediation of calcification and the implications for coral resilience in a high-CO 2 world.

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Section: Annealing Experimentsmentioning

confidence: 99%

Section: Raman 785 Nm Measurementsmentioning

confidence: 99%

Section: Pocillopora Skeletal Mappingmentioning

confidence: 99%

Section: Data Treatment Of Raman Spectramentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

The Origin and Role of Organic Matrix in Coral Calcification: Insights From Comparing Coral Skeleton and Abiogenic Aragonite

DeCarlo¹,

Ren²,

Farfán³

2018

Front. Mar. Sci.

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In Vitro Coral Biomineralization under Relevant Aragonite Supersaturation Conditions

Džakula

Fermani

Dubinsky

et al. 2019

Chemistry A European J

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The biomineralization of corals occurs under conditions of high and low supersaturation with respect to aragonite, which corresponds to day‐ or night‐time periods of their growth, respectively. Here, in vitro precipitation of aragonite in artificial seawater was investigated at a high supersaturation, allowing spontaneous nucleation and growth, as well as at low supersaturation conditions, which allowed only the crystal growth on the deliberately introduced aragonite seeds. In either chemical systems, soluble organic matrix (SOM) extracted from Balanophyllia europaea (light sensitive) or Leptopsammia pruvoti (light insensitive) was added. The analyses of the kinetic and thermodynamic data of aragonite precipitation and microscopic observations showed that, at high supersaturation, the SOMs increased the induction time, did not affect the growth rate and were incorporated within aggregates of nanoparticles. At low supersaturation, the SOMs affected the aggregation of overgrowing crystalline units and did not substantially change the growth rate. On the basis of the obtained results we can infer that at high supersaturation conditions the formation of nanoparticles, which is typically observed in the skeleton's early mineralization zone may occur, whereas at low supersaturation the overgrowth on prismatic seeds observed in the skeleton fiber zone is a predominant process. In conclusion, this research brings insight on coral skeletogenesis bridging physicochemical (supersaturation) and biological (role of SOM) models of coral biomineralization and provides a source of inspiration for the precipitation of composite materials under different conditions of supersaturation.

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The role of irradiance in controlling coralline algal calcification

Krieger

Nelson

Grand

et al. 2023

Limnology & Oceanography

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Coralline algae are an essential element of benthic ecosystems throughout the ocean's photic zone. Yet, the role of light in shaping the physiology of coralline algae from cold‐water, low‐light habitats is poorly understood. Here, we assess the calcification physiology of five cool temperate coralline algae in response to different irradiance levels over 3 months. We show that in contrast to current models focused on warmer water species, previously observed enhancement of calcification rates by photosynthesis is largely limited to lower irradiances, and that the removal of CO2 from the calcifying fluid is not the underlying mechanism of this enhancement. Instead, this most likely occurs via two processes: (1) increased ion pumping rates to elevate the calcium carbonate saturation state in the calcifying fluid; and (2) a higher daytime pH in the diffusion boundary layer that raises calcifying fluid pH. However, as irradiance increases, ion pumping becomes increasingly saturated limiting further enhancements. Our results also suggest the existence of two calcification strategies in coralline algae and indicate that magnesium incorporation is determined by the magnesium to calcium ratio in the calcifying fluid ([Mg]CF/[Ca]CF). This study adds to our mechanistic understanding of calcification in coralline algae and fills in much needed knowledge about the role of light in controlling their physiology.

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Coral calcifying fluid aragonite saturation states derived from Raman spectroscopy

Cited by 57 publications

References 91 publications

The Origin and Role of Organic Matrix in Coral Calcification: Insights From Comparing Coral Skeleton and Abiogenic Aragonite

The Origin and Role of Organic Matrix in Coral Calcification: Insights From Comparing Coral Skeleton and Abiogenic Aragonite

In Vitro Coral Biomineralization under Relevant Aragonite Supersaturation Conditions

The role of irradiance in controlling coralline algal calcification

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