Environmental control of the isotopic composition of subfossil coccolith calcite: Are laboratory culture data transferable to the natural environment?

Hermoso, Michaël; Candelier, Yaël; Browing, Thomas J.; Minoletti, Fabrice

doi:10.1016/j.grj.2015.05.002

Cited by 28 publications

(40 citation statements)

References 46 publications

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“…From a geological perspective, the data indicate that seawater pH influences the stable carbon isotopic compositions of coccolith calcite and that this parameter has to be considered for interpreting δ 13 C in the sedimentary archive [Zeebe, 2001;Rousselle et al, 2013;Hermoso et al, 2015]. The sensitivity of coccolith δ 13 C values to increasing ambient CO 2 concentrations in the culture medium at constant pH was previously made by Rickaby et al [2010] on the same species.…”

Section: Geological Implicationsmentioning

confidence: 82%

“…It has to be recognized that separating coccoliths from sediments remains challenging and is relatively time-demanding comparing to foraminifera hand-picking. However, a growing number of paleoceanographic studies have successfully focused on the use of the coccolith geochemistry since it is now possible to achieve near-monospecific analyses on calcareous nannofossils [Hermoso et al, 2009a[Hermoso et al, , 2009bMinoletti et al, 2009;Bolton et al, 2012;Rousselle et al, 2013;Minoletti et al, 2014;Hermoso et al, 2015].…”

Section: Introductionmentioning

confidence: 99%

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Control of ambient pH on growth and stable isotopes in phytoplanktonic calcifying algae

Hermoso

2015

Paleoceanography

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The present work examines the relationship between pH-induced changes in growth and stable isotopic composition of coccolith calcite in two coccolithophore species with a geological perspective. These species (Gephyrocapsa oceanica and Coccolithus pelagicus) with differing physiologies and vital effects possess a growth optimum corresponding to average pH of surface seawater in the geological period during their first known occurrence. The "ancestral" C. pelagicus has much wider pH tolerance in terms of growth rates than the more recently evolved G. oceanica. Diminished growth rates are explained by the challenge of proton translocation into the extracellular environment at low pH and enhanced aqueous CO 2 limitation at high pH. Reducing the cell dynamics in this way leads to a lower degree of oxygen isotopic disequilibrium in G. oceanica. In contrast, the slower growing species C. pelagicus, which typically precipitates near-equilibrium calcite, does not show any modulation of oxygen isotope signals with changing pH. Overall, carbon and oxygen isotope compositions are best explained by the degree of utilization of the internal dissolved inorganic carbon (DIC) pool and the dynamics of isotopic reequilibration inside the cell. Thus, the "carbonate ion effect" may not apply to coccolithophores. This difference with foraminifera can be traced to different modes of DIC incorporation into these two distinct biomineralizing organisms. From a geological perspective, these findings have implications for refining the use of oxygen isotopes to infer more reliable sea surface temperatures (SSTs) from fossil carbonates and contribute to a better understanding of how climate-relevant parameters are recorded in the sedimentary archive.

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Section: Geological Implicationsmentioning

confidence: 82%

Section: Introductionmentioning

confidence: 99%

Control of ambient pH on growth and stable isotopes in phytoplanktonic calcifying algae

Hermoso

2015

Paleoceanography

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“…In nature, environmental parameters generally co-vary, such as sea surface temperatures and pCO 2 concentrations. This is illustrated by the recent natural environment study by Hermoso et al (2015) analysing coccoliths microseparated from core top sediments, which further illustrates the intricate (multi-parameter) control of coccolith oxygen and carbon isotope compositions (δ 18 O and δ 13 C, respectively).…”

Section: Published By Copernicus Publications On Behalf Of the Europementioning

confidence: 87%

“…This approach could complement alkenone-derived palaeo-CO 2 estimates by significantly contribute constraining seawater δ 13 C CO 2 composition and the so-called "b" coefficient (Pagani, 2002;Pagani et al, 2005). This novel approach (recently outlined in Hermoso, 2015, andHermoso et al, 2015) will require coupled foraminiferal data that may serve as an inorganic reference (Spero et al, 2003). In addition, it appears possible to reconstruct cell geometry via morphometric measurements made on fossil coccoliths (Henderiks and Rickaby, 2007;Henderiks, 2008;Henderiks and Pagani, 2008), as this parameter is of paramount importance for inferring algal growth dynamics and cell size in the absence of preserved coccospheres in the sedimentary register, except in some peculiar settings (Gibbs et al, 2013).…”

Section: Outlook For Coccolith-based Palaeoceanographic Reconstructionsmentioning

confidence: 99%

Vanishing coccolith vital effects with alleviated carbon limitation

et al. 2016

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Abstract. By recreating a range of geologically relevant concentrations of dissolved inorganic carbon (DIC) in the laboratory, we demonstrate that the magnitude of the vital effects in both carbon and oxygen isotopes of coccolith calcite of multiple species relates to ambient DIC concentration. Under high DIC levels, all the examined coccoliths exhibit significantly reduced isotopic offsets from inorganic calcite compared to the substantial vital effects expressed at low (preindustrial and present-day) DIC concentrations. The supply of carbon to the cell exerts a primary control on biological fractionation in coccolith calcite via the modulation of coccolithophore growth rate, cell size and carbon utilisation by photosynthesis and calcification, altogether accounting for the observed interspecific differences between coccolith species. These laboratory observations support the recent hypothesis from field observations that the appearance of interspecific vital effect in coccolithophores coincides with the long-term Neogene decline of atmospheric CO 2 concentrations and bring further valuable constraints by demonstrating a convergence of all examined species towards inorganic values at high pCO 2 regimes. This study provides palaeoceanographers with a biogeochemical framework that can be utilised to further develop the use of calcareous nannofossils in palaeoceanography to derive sea surface temperature and pCO 2 levels, especially during periods of relatively elevated pCO 2 concentrations, as they prevailed during most of the Meso-Cenozoic.

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“…In sequences postdating the Late Miocene, large isotope vital effects have been reported in coccoliths (21). This was attributed to the consequence of relatively low pCO 2 concentrations, as DIC/CO 2 aq limitation is thought to be the main cause of the vital effects in these biominerals (20,21,(23)(24)(25)(26)(27). In contrast, studies of laboratory cultures and downcore sediments indicate that the vital effect in coccoliths (regardless of taxonomy) was limited and invariant when pCO 2 concentrations in the atmosphere were above ∼500 ppm, as was the case during the time period investigated (28, 29) (see SI Materials and Methods for further explanations on the relation…”

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confidence: 99%

Equatorial heat accumulation as a long-term trigger of permanent Antarctic ice sheets during the Cenozoic

Tremblin

Hermoso

Minoletti

2016

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

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Growth of the first permanent Antarctic ice sheets at the Eocene−Oligocene Transition (EOT), ∼33.7 million years ago, indicates a major climate shift within long-term Cenozoic cooling. The driving mechanisms that set the stage for this glaciation event are not well constrained, however, owing to large uncertainties in temperature reconstructions during the Eocene, especially at lower latitudes. To address this deficiency, we used recent developments in coccolith biogeochemistry to reconstruct equatorial Atlantic sea surface temperature (SST) and atmospheric pCO 2 values from pelagic sequences preceding and spanning the EOT. We found significantly more variability in equatorial SSTs than previously reported, with pronounced cooling from the Early to Middle Eocene and subsequent warming during the Late Eocene. Thus, we show that the Antarctic glaciation at the Eocene−Oligocene boundary was preceded by a period of heat accumulation in the low latitudes, likely focused in a progressively contracting South Atlantic gyre, which contributed to cooling high-latitude austral regions. This prominent redistribution of heat corresponds to the emplacement of a strong meridional temperature gradient that typifies icehouse climate conditions. Our equatorial coccolith-derived geochemical record thus highlights an important period of global climatic and oceanic upheaval, which began 4 million years before the EOT and, superimposed on a longterm pCO 2 decline, drove the Earth system toward a glacial tipping point in the Cenozoic. . These records exhibit rather conflicting proxy data for the TDP and overall long-term cooling for the Atlantic sites 925 and 929. There is, however, no clear and significant cooling trend from the Early to Middle Eocene that indicates the termination of the Early Eocene Climatic Optimum (Fig. 1A). Furthermore, recent quality-checked SSTs for ODP 925 and 929 sites using the Ring Index indicate relatively similar temperatures between the Late Eocene and the Early Oligocene (5). In contrast, high-latitude sites are consistent in demonstrating appreciable cooling of austral subpolar regions during much of the Eocene (3,4,(6)(7)(8). This apparent lack of substantial temperature change in the intertropical belt during the Eocene and across the EOT remains an enigmatic feature that complicates our understanding of the interplay between seawater temperatures at a global scale, pCO 2 , and changes in global ocean circulations in the context of new Southern Ocean gateways (9-14). The paucity of low-latitude data, especially in the Pacific Ocean, prevents the reconstruction of the latitudinal temperature gradient, much needed for the successful modeling of processes that drove the greenhouse to icehouse transition (10, 15, 16).As an alternative to the relatively poor preservation of the foraminifera and issues with the calibration of organic-based proxies (1, 5, 17), this study exploits the coccoliths as a source of paleoclimatic information. Coccolithophores, single-celled phytoplankton algae, are a key componen...

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Environmental control of the isotopic composition of subfossil coccolith calcite: Are laboratory culture data transferable to the natural environment?

Cited by 28 publications

References 46 publications

Control of ambient pH on growth and stable isotopes in phytoplanktonic calcifying algae

Control of ambient pH on growth and stable isotopes in phytoplanktonic calcifying algae

Vanishing coccolith vital effects with alleviated carbon limitation

Equatorial heat accumulation as a long-term trigger of permanent Antarctic ice sheets during the Cenozoic

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