NOAA/WDS Paleoclimatology - Buccoo Reef - Stable Isotope and Luminescence Data

The geochemical composition of skeletons from corals growing around the island of Tobago is impacted by several environmental forcing factors. This project studied the stable oxygen and carbon isotopic composition, extension, skeletal luminescence, and the carbon and nitrogen isotopic composition of organic material contained in skeletons of the scleractinian corals Montastraea faveolata and Siderastrea siderea living at a relatively shallow depth (2-14 m) at Tobago. On an annual basis, the Orinoco River delivers organics-laden, lower salinity waters into the tropical North Atlantic where currents carry it north and west to Tobago and the eastern Caribbean. In addition, the Intertropical Convergence Zone (ITCZ) interacts with sea surface temperature (SST) and Venezuelan precipitation affecting the annual Orinoco floods. The wide-ranging effects of El Niņo-Southern Oscillation (ENSO) also extend over South America and into the tropical North Atlantic. All these factors are suggested to influence the d18O of the coral skeletons, which is not simplistically related to either SST or the discharge of Orinoco. These forcing factors, each with independent oscillations in strength and phase, interact to produce a complex geochemical signal in Tobago coral skeletons.