SGER: A History of Paleo-Hurricane Activity Recorded in the Stable Isotope Composition of Coral Skeleton

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This proposal describes a novel idea and a new technique to identify intense, landfalling hurricanes in the geologic record. It is based on the fact that hurricanes produce a large amount of rainfall with a very different oxygen isotope composition from that of normal summer rainfall. Hurricane rainfall is also isotopically distinct from water in lakes, rivers and streams, groundwater and the sea surface. It therefore comprises a natural isotope spike which is likely to be incorporated into the calcium carbonate skeletons of aquatic organisms. Although the isotope spike in seawater will quickly dissipate through mixing and dilution, if incorporated into skeletal carbonate it will remain preserved for centuries or even millennia as a record of each hurricanes' passage. We predict that the CaCO2 skeletons of massive, long-lived corals inhabiting shallow reef in the Caribbean and Gulf of Mexico contain this isotope spike and therefore preserve a record of many of the hurricanes which have made U.S. landfall over the past several centuries. We will test this prediction by measuring the isotope composition of corals from the Dominican Republic, an island hit by several intense hurricanes over the past few decades.