%0 Journal Article
%T Reconstruction of seasonal temperature variability in the tropical Pacific Ocean from the shell of the scallop, <i>Comptopallium radula</i>
%+ Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR)
%+ CAMELIA - Caractérisation et modélisation des échanges dans des lagons soumis aux influences terrigènes et anthropiques
%+ Observatoire océanologique de Banyuls (OOB)
%+ Department of Geological Sciences [Stanford] (GS)
%+ Centre d'océanologie de Marseille (COM)
%A Thébault, Julien
%A Chauvaud, Laurent
%A Clavier, Jacques
%A Guarini, Jennifer
%A Dunbar, Robert B.
%A Fichez, Renaud
%A Mucciarone, David A.
%A Morize, Eric
%Z This work was supported by IRD, the Programme National Environnement Côtier (PNEC) and the ACIPECTEN. It was part of a 3-year research program funded by IRD and the Région Bretagne.
%< avec comité de lecture
%@ 0016-7037
%J Geochimica et Cosmochimica Acta
%I Elsevier
%V 71
%N 4
%P 918-928
%8 2007
%D 2007
%R 10.1016/j.gca.2006.10.017
%Z Environmental Sciences
%Z Sciences of the Universe [physics]/Earth Sciences/Geochemistry
%Z Environmental Sciences/Global ChangesJournal articles
%X We investigated the oxygen isotope composition (d<sup>18</sup>O) of shell striae from juvenile <i>Comptopallium radula</i> (Mollusca; Pectinidae) specimens collected live in New Caledonia. Bottom-water temperature and salinity were monitored in-situ throughout the study period. External shell striae form with a 2-day periodicity in this scallop, making it possible to estimate the date of precipitation for each calcite sample collected along a growth transect. The oxygen isotope composition of shell calcite (d<sup>18</sup>O<sub>shell calcite</sub>) measured at almost weekly resolution on calcite accreted between August 2002 and July 2003 accurately tracks bottom-water temperatures. A new empirical paleotemperature equation for this scallop species relates temperature and d<sup>18</sup>O<sub>shell calcite</sub>: t(°C)=20.00(+/-0.61)-3.66(+/-0.39)x(d<sup>18</sup>O<sub>shell calcite VPDB</sub> -d<sup>18</sup>O<sub>water VSMOW</sub>) The mean absolute accuracy of temperature estimated using this equation is 1.0 °C at temperatures between 20 and 30 °C. Uncertainties regarding the precise timing of CaCO<sub>3</sub> deposition and the actual variations in d<sup>18</sup>O<sub>water</sub> at our study sites probably contribute to this error. Comparison with a previously published empirical paleotemperature equation indicates that <i>C. radula</i> calcite is enriched in <sup>18</sup>O by ~0.7‰ relative to equilibrium. Given the direction of this offset and the lack of correlation between shell growth rate and d<sup>18</sup>O<sub>shell calcite</sub>, this disequilibrium is unlikely to be related to kinetic isotope effects. We suggest that this enrichment reflects (1) a relatively low pH in the scallop's marginal extrapallial fluid (EPF), (2) an isotopic signature of the EPF different from that of seawater, or (3) Rayleigh fractionation during the biocalcification process. Relative changes in d<sup>18</sup>O<sub>shell calcite</sub> reflect seawater temperature variability at this location and we suggest that the shell of <i>C. radula</i> may be useful as an archive of past seawater temperatures.
%G English
%2 https://hal.science/hal-00449317/document
%2 https://hal.science/hal-00449317/file/Thebault_et_al_2007.pdf
%L hal-00449317
%U https://hal.science/hal-00449317
%~ IRD
%~ SDE
%~ INSU
%~ UNIV-BREST
%~ UPMC
%~ CNRS
%~ UNIV-AMU
%~ IFREMER
%~ IUEM
%~ LEMAR
%~ THESES_IUEM
%~ GIP-BE
%~ UMS_COM
%~ AGROPOLIS
%~ CMM
%~ SORBONNE-UNIVERSITE
%~ SU-SCIENCES
%~ SU-SCI
%~ UMS-2348
%~ SU-TI
%~ ALLIANCE-SU