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| Guillermic, Maxence; Cameron, Louise P.; De Corte, Ilian; Misra, Sambuddha; Bijma, Jelle; De Beer, Dirk; Reymond, Claire E.; Westphal, Hildegard; Ries, Justin B.; Eagle, Robert A.. |
| The combination of thermal stress and ocean acidification (OA) can more negatively affect coral calcification than an individual stressors, but the mechanism behind this interaction is unknown. We used two independent methods (microelectrode and boron geochemistry) to measure calcifying fluid pH (pH(cf)) and carbonate chemistry of the corals Pocillopora damicornis and Stylophora pistillata grown under various temperature and pCO(2) conditions. Although these approaches demonstrate that they record pH(cf) over different time scales, they reveal that both species can cope with OA under optimal temperatures (28 degrees C) by elevating pH(cf) and aragonite saturation state (Omega(cf)) in support of calcification. At 31 degrees C, neither species elevated these... |
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| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00686/79846/82675.pdf |
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| Liu, Yi-wei; Eagle, Robert A.; Aciego, Sarah M.; Gilmore, Rosaleen E.; Ries, Justin B.. |
| Ocean acidification will potentially inhibit calcification by marine organisms; however, the response of the most prolific ocean calcifiers, coccolithophores, to this perturbation remains under characterized. Here we report novel chemical constraints on the response of the widespread coccolithophore species Ochrosphaera neapolitana (O. neapolitana) to changing-CO2 conditions. We cultured this algae under three pCO(2)-controlled seawater pH conditions (8.05, 8.22, and 8.33). Boron isotopes within the algae's extracellular calcite plates show that this species maintains a constant pH at the calcification site, regardless of CO2-induced changes in pH of the surrounding seawater. Carbon and oxygen isotopes in the algae's calcite plates and carbon isotopes in... |
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| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00452/56323/72132.pdf |
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| Tripati, Aradhna K.; Sahany, Sandeep; Pittman, Dustin; Eagle, Robert A.; Neelin, J. David; Mitchell, Jonathan L.; Beaufort, Luc. |
| During the Last Glacial Maximum, tropical sea surface temperatures were 1 to 3 degrees C cooler than present(1-4), but the altitude of the snowlines of tropical glaciers(5,6) was lower than would be expected in light of these sea surface temperatures. Indeed, both glacial and twentieth-century snowlines seem to require lapse rates that are steeper than a moist adiabat(7,8). Here we use estimates of Last Glacial Maximum sea surface temperature in the Indo-Pacific warm pool based on the clumped isotope palaeotemperature proxy in planktonic foraminifera and coccoliths, along with radiative-convective calculations of vertical atmospheric thermal structure, to assess the controls on tropical glacier snowlines. Using extensive new data sets for the region, we... |
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| Ano: 2014 |
URL: https://archimer.ifremer.fr/doc/00290/40169/39048.pdf |
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| Sutton, Jill N.; Liu, Yi-wei; Ries, Justin B.; Guillermic, Maxence; Ponzevera, Emmanuel; Eagle, Robert A.. |
| The boron isotope composition (δ11B) of marine biogenic carbonates has been predominantly studied as a proxy for monitoring past changes in seawater pH and carbonate chemistry. However, a number of assumptions regarding chemical kinetics and thermodynamic isotope exchange reactions are required to derive seawater pH from δ11B biogenic carbonates. It is also probable that δ11B of biogenic carbonate reflects seawater pH at the organism's site of calcification, which may or may not reflect seawater pH. Here, we report the development of methodology for measuring the δ11B of biogenic carbonate samples at the multi-collector inductively coupled mass spectrometry facility at Ifremer (Plouzané, France) and the evaluation of δ11BCaCO3 in a diverse range of marine... |
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| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00430/54152/55481.pdf |
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| Liu, Yi-wei; Sutton, Jill; Ries, Justin B.; Eagle, Robert A.. |
| The response of marine-calcifying organisms to ocean acidification (OA) is highly variable, although the mechanisms behind this variability are not well understood. Here, we use the boron isotopic composition (δ11B) of biogenic calcium carbonate to investigate the extent to which organisms’ ability to regulate pH at their site of calcification (pHCF) determines their calcification responses to OA. We report comparative δ11B analyses of 10 species with divergent calcification responses (positive, parabolic, threshold, and negative) to OA. Although the pHCF is closely coupled to calcification responses only in 3 of the 10 species, all 10 species elevate pHCF above pHsw under elevated pCO2. This result suggests that these species may expend additional energy... |
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| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00609/72072/70780.pdf |
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| Howes, Ella L.; Eagle, Robert A.; Gattuso, Jean-pierre; Bijma, Jelle. |
| Anthropogenic carbon perturbation has caused decreases in seawater pH and increases in global temperatures since the start of the 20th century. The subsequent lowering of the saturation state of CaCO3 may make the secretion of skeletons more problematic for marine calcifiers. As organisms that precipitate thin aragonite shells, thecosome pteropods have been identified as being particularly vulnerable to climate change effects. Coupled with their global distribution, this makes them ideal for use as sentinel organisms. Recent studies have highlighted shell dissolution as a potential indicator of ocean acidification; however, this metric is not applicable for monitoring pH changes in supersaturated basins. In this study, the novel approach of high resolution... |
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| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00377/48792/69884.pdf |
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