COUPLING TROPICAL CYCLONE FREQUENCY AND CLIMATE DYNAMICS; A 1500 YEAR RECORD IN THE PELICAN CAYES BELIZE

Efforts to discern relationships between climate dynamics and tropical cyclones have only recently begun to be deciphered and prove to be extremely complex. Data reconstruction of past tropical cyclone frequency and water temperature can be used to develop preliminary paleoclimate scenarios that may have encouraged tropical cyclone development. The location of Belize within the western Caribbean Sea makes it susceptible to numerous climate perturbations such as the Intertropical Convergence Zone, North Atlantic Oscillation, El Niño Southern Oscillation, and the West African Monsoons, which all vary temporally and spatially. For this study, 5 m cores were sampled from two reef lagoons, Elbow and Manatee Caye, in the Pelican Cayes off coastal Belize. At the base of each core, approximately 0.20 m of presumably in situ coral was found. Grain size analysis at 1 cm intervals throughout the cores determined they are dominantly composed of fine, light colored carbonate silt punctuated by coarser sediment layers. We attribute coarser sediment layers within the cores to proximal tropical cyclone/storm-driven deposition (~25 km radius). Radiocarbon dating of plant macrofossils and basal coral, along with Cs¹³⁷ and Pb²¹⁰ provides good chronology and sedimentation rate of ~3.5 mm/yr from1500 to 150 years BP. Isotope ratio mass spectrometry performed on tests of calcareous benthic foraminifera throughout the cores and basal coral were used to determine δ¹⁸O and δ¹³C. Variations in the isotopic composition are used to establish temperature and salinity fluctuations over differing temporal scales. Comparing washovers and temperature/salinity records from the Pelican Cayes to previously published records will help us to further understand the climate dynamics which may have enhanced tropical cyclone development and/or intensity over the past 1500 years.