A SEA SURFACE TEMPERATURE RECONSTRUCTION FROM MODERN AND FOSSIL CORALS FROM THE DOMINICAN REPUBLIC

The increase in global temperatures that occurred over the last century has been driven by anthropogenic activity and natural climate variability. Quantifying the contribution of anthropogenic forcing and natural climatic variations to the last century of warming is challenging due to the limited length of the observational period. Assessment of natural climate system prior to the onset of anthropogenic influences will provide a better understanding of the influence of anthropogenic activity onto the climate system. This study aimed on reconstructing Sea Surface Temperatures (SST) using Sr/Ca ratios from the skeleton of Orbicella spp. fossil corals (9.0 ± 200 to 5.6 ± 29 ka, n = 5) collected from different facies of a well-preserved reef (Cañada Honda) located on the slopes of Enriquillo Lake Valley, Dominican Republic (DR). No evidence of secondary precipitation and/or neomorphism to calcite occurred in the coral skeleton, corroborated by XRD and SEM. A modern Orbicella spp. coral from Barahona Bay, DR, ~70 km from the fossil reef exposure, was used to develop a Sr/Ca-SST calibration equation applicable to the fossil specimens. Coral extension rates indicate slow growth of fossil corals (1.32 to 1.98 mm/year) relative to the modern coral (7.34 mm/year). Sr/Ca-SST average values obtained were 27.8 ± 1.1 °C for modern coral and ranged from 18.79 ± 1.2 to 26.86 ± 2.0 °C for fossil corals. Results provides snapshots of reconstructed SST from fossil Orbicella spp. corals along with a modern analog to evaluate changes in SST variability throughout the early to mid-Holocene.