Evidence for the non-influence of salinity variability on the <i>Porites</i> coral Sr/Ca palaeothermometer

• Main Authors: M. Moreau, T. Corrège, E. P. Dassié, F. Le Cornec
• Format: Article
• Language: English
• Published: Copernicus Publications 2015-03-01
• Series: Climate of the Past
• Online Access: http://www.clim-past.net/11/523/2015/cp-11-523-2015.pdf

<i>Porites</i> coral-based sea surface temperature (SST) reconstructions are obtained from the measurement of skeleton Sr/Ca ratio. However, the influence of salinity in the incorporation of these trace elements in the <i>Porites</i> aragonitic skeleton is still poorly documented. Laboratory experiments indicate that in three different coral species (not including the widely used <i>Porites</i> genus), salinity does not influence the Sr/Ca thermometer. In this study, we test the salinity effect on <i>Porites</i> Sr/Ca-based SST reconstructions at monthly and interannual timescales in open-ocean environmental conditions. We use a large spatial compilation of published <i>Porites</i> data from the Red Sea and Pacific and Indian oceans. Additionally to those published records, we add a new eastern Pacific coral Sr/Ca record from Clipperton Atoll. <br><br> Using two different salinity products (Simple Ocean Data Assimilation (SODA) SSS reanalyses version 2.2.4, Carton and Giese, 2008; and instrumental SSS from the Institut de Recherche pour le Développement, France (IRD) Delcroix et al., 2011), we find no evidence of salinity bias on the Sr/Ca SST proxy at monthly and interannual timescales. We conclude that <i>Porites</i> Sr/Ca is a reliable palaeothermometer that is not influenced by salinity variability.