Clumped Signatures of Shallow Water Corals in Tobago

Abstract:

The island of Tobago is seasonally bathed by the waters from the Orinoco and the Amazon and the δ¹⁸O of the coral skeleton responds annually to a change in temperature of approximately 4 °C as well as changes in the magnitude of outflow of the Orinoco, Amazon, and precipitation associated with the ITCZ. The clumped isotope makes it possible to distinguish the temperature induced δ¹⁸O signal from that exerted by the freshwater. We have utilized a specimen of Diploria strigosa collected in 1991 which has an extension rate of about 2 cm/yr allows between 4-5 samples to be collected within a yearly growth increment. Our data reveals temperature between 24 and 28 °C consistent with actual measurements and not offset towards lower values as in some previous studies. Once the temperature has been calculated it is possible to extract the δ¹⁸O of the water using one of the paleotemperature equations established for corals.