Planktic foraminifera shell chemistry response to seawater chemistry: Pliocene–Pleistocene seawater Mg/Ca, temperature and sea level change

Evans, David; Brierley, Chris; Raymo, Maureen E; Erez, Jonathan; Müller, Wolfgang

doi:10.1016/j.epsl.2016.01.013

Cited by 90 publications

(198 citation statements)

References 48 publications

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“…No significant variation with Mg / Ca sw was observed (Fig. 3), consistent with previous observations that varying seawater [Mg] does not change growth rates in foraminifera (Evans et al, 2015(Evans et al, , 2016a. Similarly, no effect of temperature on CI was observed (Fig.…”

Section: Culture Resultssupporting

confidence: 81%

“…Uncertainty on pH is therefore calculated as two standard errors on the mean of each culture flask pHs during cultures. For those experiments intended to test Mg incorporation (Evans et al, 2016a), pH monitoring during culture was less frequent, and this is reflected in a more conservative approximation of pH uncertainty in these cultures. In total, we collate calcification intensity data from 11 separate culture experiments, with temperatures ranging from 22.8 to 27.8 • C, seawater Mg / Ca ratios ranging from 2.17 to 6.25 mol mol −1 , and pH (total scale) ranging from 7.54 to 8.20.…”

Section: Culturingmentioning

confidence: 99%

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Size-dependent response of foraminiferal calcification to seawater carbonate chemistry

et al. 2017

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Abstract. The response of the marine carbon cycle to changes in atmospheric CO 2 concentrations will be determined, in part, by the relative response of calcifying and non-calcifying organisms to global change. Planktonic foraminifera are responsible for a quarter or more of global carbonate production, therefore understanding the sensitivity of calcification in these organisms to environmental change is critical. Despite this, there remains little consensus as to whether, or to what extent, chemical and physical factors affect foraminiferal calcification. To address this, we directly test the effect of multiple controls on calcification in culture experiments and core-top measurements of Globigerinoides ruber. We find that two factors, body size and the carbonate system, strongly influence calcification intensity in life, but that exposure to corrosive bottom waters can overprint this signal post mortem. Using a simple model for the addition of calcite through ontogeny, we show that variable body size between and within datasets could complicate studies that examine environmental controls on foraminiferal shell weight. In addition, we suggest that size could ultimately play a role in determining whether calcification will increase or decrease with acidification. Our models highlight that knowledge of the specific morphological and physiological mechanisms driving ontogenetic change in calcification in different species will be critical in predicting the response of foraminiferal calcification to future change in atmospheric pCO 2 .

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Section: Culture Resultssupporting

confidence: 81%

Section: Culturingmentioning

confidence: 99%

Size-dependent response of foraminiferal calcification to seawater carbonate chemistry

et al. 2017

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“…However, given the multivariate nature of Mg/Ca, it would be beneficial to use information from other temperature proxies in a formal hierarchical model structure. Previous work has already explored this avenue by combining Mg/Ca measurements with TEX 86 or Δ47 to estimate Mg/Ca sw (e.g., Evans et al, ; Evans, Brierley, et al, ; O'Brien et al, ) and by combining Mg/Ca with δ 18 O to infer δ 18 O sw or salinity (e.g., Oppo et al, ; Thirumalai et al, ; Tierney et al, ). Future work might explore incorporating δ 11 B and B/Ca estimates of pH and calcite saturation state, respectively.…”

Section: Discussionmentioning

confidence: 99%

“…Shading encloses the 95% CI of an ensemble of Gaussian smoothed fits to the data, used in the seawater‐enabled BAYMAG models. (b) Relationship between observed Mg/Ca s w and linear predictions of Mg/Ca s w from Mg/Ca of calcite in laboratory inorganic precipitation (Mucci & Morse, ) and foraminiferal culture studies (De Nooijer et al, ; Delaney et al, ; Evans et al, ; Evans, Brierley, et al, ; Hauzer et al, ; Mewes et al, ; Raitzsch et al, ; Segev & Erez, ).…”

Section: Use Of Baymag On Longer Geological Timescalesmentioning

confidence: 99%

“…More recently, it has been proposed that the temperature sensitivity of Mg/Ca in foraminifera changes with Mg/Ca sw (Evans, Brierley, et al, ). However, thus far this has only been detected in a culture experiment of G. ruber ; a study of benthic foraminiferal species did not detect a change in temperature sensitivity with Mg/Ca sw (De Nooijer et al, ).…”

Section: Use Of Baymag On Longer Geological Timescalesmentioning

confidence: 99%

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Bayesian Calibration of the Mg/Ca Paleothermometer in Planktic Foraminifera

Tierney

Malevich

Gray

et al. 2019

Paleoceanog and Paleoclimatol

146

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The Mg/Ca ratio of planktic foraminifera is a widely used proxy for sea-surface temperature but is also sensitive to other environmental factors. Previous work has relied on correcting Mg/Ca for nonthermal influences. Here, we develop a set of Bayesian models for Mg/Ca in four major planktic groups-Globigerinoides ruber (including both pink and white chromotypes), Trilobatus sacculifer, Globigerina bulloides, and Neogloboquadrina pachyderma (including N. incompta)-that account for the multivariate influences on this proxy in an integrated framework. We use a hierarchical model design that leverages information from both laboratory culture studies and globally distributed core top data, allowing us to include environmental sensitivities that are poorly constrained by core top observations alone. For applications over longer geological timescales, we develop a version of the model that incorporates changes in the Mg/Ca ratio of seawater. We test our models-collectively referred to as BAYMAG-on sediment trap data and on representative paleoclimate time series and demonstrate good agreement with observations and independent sea-surface temperature proxies. BAYMAG provides probabilistic estimates of past temperatures that can accommodate uncertainties in other environmental influences, enhancing our ability to interpret signals encoded in Mg/Ca. Plain Language SummaryThe amount of magnesium (Mg) incorporated into the calcite shells of tiny protists called foraminifera is determined by the temperature of the water in which they grew. This allows paleoclimatologists to measure the magnesium-to-calcium (Mg/Ca) ratio of fossil foraminiferal shells and determine how past sea-surface temperatures have changed. However, other factors can influence Mg/Ca, like the salinity and pH of seawater. Here, we develop Bayesian models of foraminiferal Mg/Ca that account for all of the influences on Mg/Ca and show how we can use these to improve our interpretations of Mg/Ca data. Culture experiments provide precise constraints on environmental sensitivities but are limited in that laboratory conditions are not perfect analogs for the natural environment. Sediment traps have an advantage in that seasonality of foraminiferal occurrence and corresponding ocean temperatures are well constrained, but they do not account for the effects of dissolution or bioturbation. Sedimentary core tops integrate effects associated with both occurrence and preservation and are thus better analogs for the conditions typical of the geological record, but uncertainties in seasonal preferences and the depth of calcification can in some cases lead to misleading inference of secondary environmental sensitivities (Hertzberg & Schmidt, 2013;Hönisch et al., 2013).Here, we use both core top and laboratory culture data to develop a suite of Bayesian hierarchical models for Mg/Ca. We collate over 1,000 sedimentary Mg/Ca measurements to formulate new calibrations for four major planktic groups: Globigerinoides ruber (including both pink and white chromotypes), Trilobat...

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The Impacts of Seawater Mg/Ca and Temperature on Element Incorporation in Benthic Foraminiferal Calcite

Nooijer

Dijk

Toyofuku

et al. 2017

Geochem Geophys Geosyst

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On geological timescales, oceanic [Mg2+] and [Ca2+] vary with changing rates of weathering, seafloor spreading and dolomite formation. Accurate reconstruction of the ratio between [Mg2+] and [Ca2+] in seawater (Mg/Casw), may potentially be reconstructed using foraminiferal Mg/Ca ratios. Since both temperature and seawater Mg/Ca impact foraminiferal Mg/Ca, successful reconstruction of Mg/Casw requires quantification of both these parameters independently on foraminiferal Mg/Ca, as well as their combined effect on Mg‐incorporation. Here we present the combined and isolated impacts of temperature and Mg/Casw on Mg incorporation in two model species, the benthic hyaline (i.e., perforate) foraminifer Elphidium crispum and porcelaneous (i.e., miliolid) foraminifer Quinqueloculina sp. using controlled growth experiments. Specimens of these two species were kept at four different temperatures (ranging from 10 to 27°C) and three Mg/Casw's (3.4, 6.4 and 8.5 mol/mol), resulting in 12 experimental conditions. Newly grown calcite was analyzed for a number of elements (Na, Mg and Sr) by laser ablation‐ICP‐MS. Results show that although the Mg/Ca varied by more than an order of magnitude between species, the sensitivity of Mg incorporation with respect to temperature appeared not to be influenced by Mg/Casw. By extension, these results may also help improving accuracy in the reconstruction of past Mg/Casw based on foraminifera with contrasting Mg/Ca.

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Planktic foraminifera shell chemistry response to seawater chemistry: Pliocene–Pleistocene seawater Mg/Ca, temperature and sea level change

Cited by 90 publications

References 48 publications

Size-dependent response of foraminiferal calcification to seawater carbonate chemistry

Size-dependent response of foraminiferal calcification to seawater carbonate chemistry

Bayesian Calibration of the Mg/Ca Paleothermometer in Planktic Foraminifera

The Impacts of Seawater Mg/Ca and Temperature on Element Incorporation in Benthic Foraminiferal Calcite

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