South Atlantic Multi-Site Calibration of Coral Oxygen Isotope Paleothermometer

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Pereira, N. S. ; Chiessi, C. M. ; Crivellari, S. ; Kilbourne, K. H. ; Kikuchi, R. K. P. ; Ferreira, B. P. ; Macedo, R. J. A. ; dos Santos, M. C. M. ; Pereira, M. G. ; da Rocha, L. S. Neves ; Sial, A. N.

• Document type: Journal article
• Source: GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS; v. 25, n. 8, p. 17-pg., 2024-08-01.

Abstract

Coral-based stable oxygen isotopes (delta O-18) have been used as a proxy for sea surface temperature (SST) since the 1970s, and delta O-18-SST calibration studies have been fundamental to assure robust and faithful SST reconstructions. Paleoclimatic studies based on corals from the tropical western South Atlantic (TWSA) are scarce, and the available coral species need to be calibrated to improve climate and environmental reconstructions. Siderastrea stellata, a slow-growing coral, is a potential species to be explored as a coral archive in the TWSA. We provide the first multi-site delta O-18-SST calibration for the coral S. stellata from three locations at the TWSA: Todos os Santos Bay, Tamandar & eacute; and the Rocas Atoll. Pseudo-coral delta O-18 calculations derived from gridded SSS and SST show that the contributions of SSS and SST to coral delta O-18 are expected to be different at each site. Weighted least squares linear regressions performed between the delta O-18 and SST generated the following calibrations equations: delta O-18 = -0.18 (+/- 0.02) x SST (degrees C) + 1.90 (+/- 0.47) for Todos os Santos Bay; delta O-18 = -0.18 (+/- 0.02) x SST (degrees C) + 1.54 (+/- 0.67) for Tamandar & eacute;; and delta O-18 = -0.16 (+/- 0.03) x SST (degrees C) + 1.24 (+/- 0.71) for the Rocas Atoll. The delta O-18-SST sensitivity of S. stellata from the TWSA is similar to that of other slow-growing species of the genus and consistent with the expected delta O-18-SST sensitivity of other species reported in the literature. These calibrations will allow future SST reconstructions based on delta O-18 records from sub-fossil and fossil S. stellata, an abundant species in the TWSA. (AU)

• FAPESP's process: 19/24349-9 - Assessing the effects of past and future climate change on Amazonian biodiversity (CLAMBIO)
• Grantee: Cristiano Mazur Chiessi
• Support Opportunities: BIOTA-FAPESP Program - Regular Research Grants
• FAPESP's process: 18/15123-4 - Past perspectives on tipping elements of the climate system: the Amazon Rainforest and the Atlantic Meridional Overturning Circulation (PPTEAM)
• Grantee: Cristiano Mazur Chiessi
• Support Opportunities: Research Grants - Research Program on Global Climate Change - Young Investigators - Phase 2