Coral Li/Ca in micro-structural domains as a temperature proxy

• Main Authors: MONTAGNA P, CORREA ML, RUGGEBERG A, MCCULLOCH M, RODOLFO METALPA R, DULLO WC, FERRIER PAGES C, FREIWALD A, HENDERSON GM, RUSSO S, SILENZI S, TAVIANI M., MAZZOLI, CLAUDIO
• Other Authors: Montagna, P, Correa, Ml, Ruggeberg, A, Mcculloch, M, RODOLFO METALPA, R, Dullo, Wc, FERRIER PAGES, C, Freiwald, A, Henderson, Gm, Mazzoli, Claudio, Russo, S, Silenzi, S, Taviani, M.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2008
• Subjects: Li/Ca; temperature proxy; vital effect; Cladocora caespitosa; Lophelia pertusa
• Online Access: http://hdl.handle.net/11577/2268098

Coral skeletons are valuable geochemical archives of environmental change, although coral physiology has to varying degrees imprinted a ‘vital effect’ complicating paleoclimate reconstructions. In order to decipher environmental from physiological effects we have utilised high sensitivity laser ablation ICPMS to examine Li/Ca variations in the aragonite theca of living specimens of shallow (C. caespitosa) and deep-water (L. pertusa) corals at different temperature depth regimes, together with samples cultured in temperaturecontrolled tanks. The Li/Ca variations at micron-resolution are large and correlated with centres of calcification versus fibrous aragonite. The Li/Ca composition of the fibrous aragonite however appears to be primarily controlled by water temperature with the distribution coefficients (DLi/Ca) of L. pertusa rapidly decreasing with increasing water temperature indicating a stronger sensitivity for Li/Ca at lower temperatures, whereas the DLi/Ca for C. caespitosa follows an exponential regression. The application of coral Li/Ca paleothermometry on specifically identified micro-structural domains thus offers a unique opportunity to reconstruct changes in water temperatures at different depths in the water column.