Oxygen isotope disequilibrium in the juvenile portion of oyster shells biases seawater temperature reconstructions

Type Article
Date 2020-08
Language English
Author(s) Huyghe Dimitri1, 2, Emmanuel Laurent3, de Rafelis Marc2, Renard Maurice3, Ropert MichelORCID4, Labourdette Nathalie3, Lartaud Franck1
Affiliation(s) 1 : Sorbonne Université, CNRS, Laboratoire d'Ecogéochimie des Environnements Benthiques, LECOB, F-66650, Banyuls-sur-mer, France
2 : Géosciences Environnement Toulouse, CNRS, IRD, Université Paul Sabatier Toulouse 3, 14 Avenue Edouard Belin, 31400, Toulouse, France
3 : Sorbonne Université, CNRS-INSU, Institut des Sciences de la Terre Paris, ISTeP, F-75005 Paris, France
4 : Ifremer, Laboratoire Environnement Ressource de Normandie, Avenue du Général de Gaulle, BP 32, 14520, Port-en-Bessin, France
Source Estuarine Coastal And Shelf Science (0272-7714) (Elsevier BV), 2020-08 , Vol. 240 , P. 106777 (8p.)
DOI 10.1016/j.ecss.2020.106777
WOS© Times Cited 10
Keyword(s) Stable isotopes, Paleoclimatology, Sclerogeochemistry, Sclerochronology, Kinetic isotope effect

For decades, bivalve shells have constituted one of the most common supports for paleoclimatic archives based on stable isotope approaches. In this work, we conducted chemical marking and recapture techniques to study the fluctuation of δ18O values of oyster shells of the species Magallana gigas reared in natural environment in Normandy (France) for two years. The results were compared to the continuous monitoring of temperature and salinity and monthly records of seawater δ18O. Isotopic measurements were performed on the hinge area that regroups the whole life of the oysters. Here we demonstrate that oysters mineralized their shells with no significant growth breaks during the two-years experiment, even at temperatures below 6 °C. The results confirm that adult oysters (i.e. > 1 yr) mineralized their shells at equilibrium. However, juvenile specimens exhibit a strong isotopic disequilibrium, with a maximum shift of the δ18O values of 3‰ in winter, likely due to kinetic isotope effects. This corresponds to a reconstructed temperature up to 13 °C warmer than expected. This work indicates that although these oyster shells can be used as an accurate archive of (paleo)environmental conditions, the shell portion mineralized during the juvenile stage (i.e. < 1 yr) should be avoided for paleotemperature reconstructions. Given the wide use of bivalve shells as environmental archives, similar studies on others species are required.

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Huyghe Dimitri, Emmanuel Laurent, de Rafelis Marc, Renard Maurice, Ropert Michel, Labourdette Nathalie, Lartaud Franck (2020). Oxygen isotope disequilibrium in the juvenile portion of oyster shells biases seawater temperature reconstructions. Estuarine Coastal And Shelf Science, 240, 106777 (8p.). Publisher's official version : https://doi.org/10.1016/j.ecss.2020.106777 , Open Access version : https://archimer.ifremer.fr/doc/00624/73622/