Li/Mg systematics in scleractinian corals: Calibration of the thermometer

• Published in: Geochimica et Cosmochimica Acta
• Main Authors: Montagna, Paolo, Mcculloch, Malcolm, Douville, Eric, López Correa, Matthias, Trotter, Julie, Rodolfo-Metalpa, Riccardo, Dissard, Delphine, Ferrier-Pagès, Christine, Frank, Norbert, Freiwald, André, Goldstein, Steve, Mazzoli, Claudio, Reynaud, Stéphanie, Rüggeberg, Andres, Russo, Simone, Taviani, Marco
• Other Authors: Istituto di Scienze Marine Bologna (ISMAR), Istituto di Science Marine (ISMAR ), National Research Council of Italy, School of Earth and Environment (UWA), The University of Western Australia (UWA), ARC Centre of Excellence in Coral Reefs Studies and Coral Genomics Group, James Cook University (JCU), James Cook University (JCU), Laboratoire des Sciences du Climat et de l'Environnement Gif-sur-Yvette (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Géochrononologie Traceurs Archéométrie (GEOTRAC), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), GeoZentrum Nordbayern, Friedrich-Alexander Universität Erlangen-Nürnberg = University of Erlangen-Nuremberg (FAU), Biocomplexité des écosystèmes coralliens de l'Indo-Pacifique (CoReUS2), Centre Scientifique de Monaco (CSM), Universität Heidelberg Heidelberg = Heidelberg University, Senckenberg Meer, GZN Erlangen, Lamont-Doherty Earth Observatory (LDEO), Columbia University New York, Dipartimento di Geoscienze Padova, Università degli Studi di Padova = University of Padua (Unipd), Department of Geosciences - Earth Sciences Fribourg, Université de Fribourg = University of Fribourg (UNIFR), Università degli Studi di Salerno = University of Salerno (UNISA)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2014
• Subjects: [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph]; Lophelia pertusa
• Online Access: https://hal.science/hal-01517474; https://hal.science/hal-01517474/document; https://hal.science/hal-01517474/file/Montagna_et_al._accepted_GCA.pdf; https://doi.org/10.1016/j.gca.2014.02.005

International audience We show that the Li/Mg systematics of a large suite of aragonitic coral skeletons, representing a wide range of species inhabiting disparate environments, provides a robust proxy for ambient seawater temperature. The corals encompass both zooxanthellate and azooxanthellate species (Acropora sp., Porites sp., Cladocora caespitosa, Lophelia pertusa, Madrepora oculata and Flabellum impensum) collected from shallow, intermediate, and deep-water habitats, as well as specimens cultured in tanks under temperature-controlled conditions. The Li/Mg ratios observed in corals from these diverse tropical, temperate, and deep-water environments are shown to be highly correlated with temperature, giving an exponential temperature relationship of: Li/Mg (mmol/mol) = 5.41 exp (−0.049 * T) (r 2 = 0.975, n = 49). Based on the standard error of the Li/Mg versus temperature correlation, we obtain a typical precision of ±0.9 °C for the wide range of species analysed, similar or better than that of other less robust coral temperature proxies such as Sr/Ca ratios.The robustness and species independent character of the Li/Mg temperature proxy is shown to be the result of the normalization of Li to Mg, effectively eliminating the precipitation efficiency component such that temperature remains as the main controller of coral Li/Mg compositions. This is inferred from analysis of corresponding Li/Ca and Mg/Ca ratios with both ratios showing strong microstructure-related co-variations between the fibrous aragonite and centres of calcification, a characteristic that we attribute to varying physiological controls on growth rate. Furthermore, Li/Ca ratios show an offset between more rapidly growing zooxanthellate and azooxanthellate corals, and hence only an approximately inverse relationship to seawater temperature. Mg/Ca ratios show very strong physiological controls on growth rate but no significant dependence with temperature, except possibly for Acropora sp. and Porites sp. A strong positive correlation is ...