A Cretaceous Scleractinian Coral with a Calcitic Skeleton

Stolarski, Jarosław; Meibom, Anders; Przeniosło, R.; Mazur, Maciej

doi:10.1126/science.1149237

Cited by 80 publications

(64 citation statements)

References 23 publications

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“…This is supported by recent geochemical and petrographic analyses of fossil scleractinia from the Cretaceous Period, which suggest that some species of scleractinian corals produced largely calcitic skeletons during calcite seas of the geologic past (Stolarski et al, 2007).…”

Section: Effect Of Seawater Mg/ca On Scleractinian Coral Mineralogysupporting

confidence: 50%

Review: geological and experimental evidence for secular variation in seawater Mg/Ca (calcite-aragonite seas) and its effects on marine biological calcification

Ries¹

2010

Biogeosciences

210

170

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Abstract. Synchronized transitions in the polymorph mineralogy of the major reef-building and sediment-producing calcareous marine organisms and abiotic CaCO 3 precipitates (ooids, marine cements) throughout Phanerozoic time are believed to have been caused by tectonically induced variations in the Mg/Ca ratio of seawater (molar Mg/Ca>2="aragonite seas", <2="calcite seas"). Here, I assess the geological evidence in support of secular variation in seawater Mg/Ca and its effects on marine calcifiers, and review a series of recent experiments that investigate the effects of seawater Mg/Ca (1.0-5.2) on extant representatives of calcifying taxa that have experienced variations in this ionic ratio of seawater throughout the geologic past.Secular variation in seawater Mg/Ca is supported by synchronized secular variations in (1) the ionic composition of fluid inclusions in primary marine halite, (2) the mineralogies of late stage marine evaporites, abiogenic carbonates, and reef-and sediment-forming marine calcifiers, (3) the Mg/Ca ratios of fossil echinoderms, molluscs, rugose corals, and abiogenic carbonates, (4) global rates of tectonism that drive the exchange of Mg 2+ and Ca 2+ along zones of ocean crust production, and (5) additional proxies of seawater Mg/Ca including Sr/Mg ratios of abiogenic carbonates, Sr/Ca ratios of biogenic carbonates, and Br concentrations in marine halite.Laboratory experiments have revealed that aragonitesecreting bryopsidalean algae and scleractinian corals and calcite-secreting coccolithophores exhibit higher rates of calcification and growth in experimental seawaters formulated with seawater Mg/Ca ratios that favor their skeletal mineral. These results support the assertion that seawater Mg/CaCorrespondence to: J. B. Ries (jries@unc.edu) played an important role in determining which hypercalcifying marine organisms were the major reef-builders and sediment-producers throughout Earth history. The observation that primary production increased along with calcification within the bryopsidalean and coccolithophorid algae in mineralogically favorable seawater is consistent with the hypothesis that calcification promotes photosynthesis within some species of these algae through the liberation of CO 2 .The experiments also revealed that aragonite-secreting bryopsidalean algae and scleractinian corals, and bacterial biofilms that secrete a mixture of aragonite and high Mg calcite, began secreting an increased proportion of their calcium carbonate as the calcite polymorph in the lower-Mg/Ca experimental seawaters. Furthermore, the Mg/Ca ratio of calcite secreted by the coccolithophores, coralline red algae, reef-dwelling animals (crustacea, urchins, calcareous tube worms), bacterial biofilms, scleractinian corals, and bryopsidalean algae declined with reductions in seawater Mg/Ca. Notably, Mg fractionation in autotrophic organisms was more strongly influenced by changes in seawater Mg/Ca than in heterotrophic organisms, a probable consequence of autotrophic organisms inducing a less controlled ...

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Section: Effect Of Seawater Mg/ca On Scleractinian Coral Mineralogysupporting

confidence: 50%

Review: geological and experimental evidence for secular variation in seawater Mg/Ca (calcite-aragonite seas) and its effects on marine biological calcification

Ries¹

2010

Biogeosciences

210

170

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“…The calcitic scleractinian Coelosmilia reported from the upper Cretaceous chalk deposits seems to conform to the model of calcite versus aragonite seas (Stolarski et al, 2007). However, although this period of the fossil coral record is relatively poorly represented ( Fig.…”

Section: Introductionmentioning

confidence: 94%

Aragonitic scleractinian corals in the Cretaceous calcitic sea

Janiszewska

Mazur

Escrig

et al. 2017

Geology

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Changes in seawater chemistry have affected the evolution of calcifying marine organisms, including their skeletal polymorph (calcite versus aragonite), which is believed to have been strongly influenced by the Mg/Ca ratio at the time these animals first emerged. However, we show that micrabaciids, a scleractinian coral clade that first appeared in the fossil record of the Cretaceous, when the ocean Mg/ Ca ratio was near the lowest in the Phanerozoic (thus a priori favoring calcitic mineralogy), formed skeletons composed exclusively of aragonite. Exceptionally preserved aragonitic coralla of Micrabacia from the Late Cretaceous Ripley Formation (southeastern USA) have skeletal microstructures identical to their modern representatives. In addition, skeletons of Micrabacia from Cretaceous chalk deposits of eastern Poland are clearly diagenetically altered in a manner consistent with originally aragonitic mineralogy. These deposits have also preserved fossils of the scleractinian Coelosmilia, the skeleton of which is interpreted as originally calcitic. These findings show that if changes in seawater Mg/Ca ratio influenced the mineralogy of scleractinian corals, the outcome was taxon specific. The aragonitic mineralogy, unique skeletal microstructures and ultrastructures, and low Mg/Ca ratios in both fossil and living micrabaciids indicate that their biomineralization process is strongly controlled and has withstood major fluctuations in seawater chemistry during the past 70 m.y. INTRODUCTIONVariation in seawater chemistry is thought to have played an important role in the evolution of skeleton-forming marine organisms and in the composition of their skeletons. The Mg/Ca ratio of seawater in particular has varied dramatically throughout the Phanerozoic (Stanley and Hardie, 1998;Porter, 2010). Abiotic precipitation experiments with seawater analogs have shown that precipitation of different CaCO 3 polymorphs is mainly controlled by the Mg/Ca ratio and temperature (Morse et al., 1997). At ~25 °C, present-day seawater ionic strength, and atmospheric CO 2 concentrations, the Mg/Ca ratio separates a regime of low-Mg calcite precipitation (Mg/Ca < 2) from a regime of aragonite/high-Mg calcite precipitation (Mg/Ca > 2) (Hardie, 1996). Based on the composition of early diagenetic carbonate cements and oolites (Sandberg, 1983), fluid-inclusion data (e.g., Lowenstein et al., 2001;Horita et al., 2002), and modeling of Mg/ Ca fluctuations linking the chemical composition of the oceans with rates of oceanic crust formation (Hardie, 1996), the Phanerozoic has thus been divided into periods of calcitic and aragonitic seas, respectively (Fig. 1). It was suggested that the carbonate polymorph of hypercalcifying marine organisms was dictated by the seawater Mg/Ca ratio: during periods with high Mg/Ca ratio, aragonite-forming organisms dominated, whereas during periods with low Mg/Ca ratio, calcite-secreting organisms flourished (Stanley and Hardie, 1998). Furthermore, it was proposed that the skeletal mineralogy of newly evolv...

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“…Some organisms currently depositing metastable carbonate phases such as aragonite and high Mg-calcite may not be able to sustain themselves under such conditions (Kuffner et al 2008), but others could possibly persist through deposition of carbonate minerals of greater stability. For example, Stolarski et al (2007) discovered that corals known to deposit aragonite actually secreted calcite during an episode of the Cretaceous Period, but the controlling mechanisms are unknown. Ries et al (2006) observed similar results for corals growing in artificial seawater of variable magnesium to calcium ratio, thus, changing the composition of the mineral phase favoured to precipitate based on thermodynamic and kinetic principles.…”

Section: Discussionmentioning

confidence: 99%

Life on the margin: implications of ocean acidification on Mg-calcite, high latitude and cold-water marine calcifiers

Andersson¹,

Mackenzie²,

Bates³

2008

Mar. Ecol. Prog. Ser.

316

307

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Future anthropogenic emissions of CO 2 and the resulting ocean acidification may have severe consequences for marine calcifying organisms and ecosystems. Marine calcifiers depositing calcitic hard parts that contain significant concentrations of magnesium, i.e. Mg-calcite, and calcifying organisms living in high latitude and/or cold-water environments are at immediate risk to ocean acidification and decreasing seawater carbonate saturation because they are currently immersed in seawater that is just slightly supersaturated with respect to the carbonate phases they secrete. Under the present rate of CO 2 emissions, model calculations show that high latitude ocean waters could reach undersaturation with respect to aragonite in just a few decades. Thus, before this happens these waters will be undersaturated with respect to Mg-calcite minerals of higher solubility than that of aragonite. Similarly, tropical surface seawater could become undersaturated with respect to Mgcalcite minerals containing ≥12 mole percent (mol%) MgCO 3 during this century. As a result of these changes in surface seawater chemistry and further penetration of anthropogenic CO 2 into the ocean interior, we suggest that (1) the magnesium content of calcitic hard parts will decrease in many ocean environments, (2) the relative proportion of calcifiers depositing stable carbonate minerals, such as calcite and low Mg-calcite, will increase and (3) the average magnesium content of carbonate sediments will decrease. Furthermore, the highest latitude and deepest depth at which cold-water corals and other calcifiers currently exist will move towards lower latitudes and shallower depth, respectively. These changes suggest that anthropogenic emissions of CO 2 may be currently pushing the oceans towards an episode characteristic of a 'calcite sea.' KEY WORDS: Ocean acidification · Calcification · Carbonate dissolution · Mg-calcite · High latitude · Aragonite · Saturation state · Calcite sea Resale or republication not permitted without written consent of the publisher Contribution to the Theme Section 'Effects of ocean acidification on marine ecosystems'OPEN PEN ACCESS CCESS

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A Cretaceous Scleractinian Coral with a Calcitic Skeleton

Cited by 80 publications

References 23 publications

Review: geological and experimental evidence for secular variation in seawater Mg/Ca (calcite-aragonite seas) and its effects on marine biological calcification

Review: geological and experimental evidence for secular variation in seawater Mg/Ca (calcite-aragonite seas) and its effects on marine biological calcification

Aragonitic scleractinian corals in the Cretaceous calcitic sea

Life on the margin: implications of ocean acidification on Mg-calcite, high latitude and cold-water marine calcifiers

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