HR: 1340h
AN: PP23B-1429    [Abstracts]
TI: Natural Variability of Environmental Proxies in Corals from an Upwelling Region
AU: * Matthews, K A
EM: kam2@sas.upenn.edu
AF: Department of Earth and Environmental Science, University of Pennsylvania, Philadelphia, PA 19104-6316 United States
AU: Grottoli, A G
EM: grottoli@sas.upenn.edu
AF: Department of Earth and Environmental Science, University of Pennsylvania, Philadelphia, PA 19104-6316 United States
AU: McDonough, W F
EM: mcdonough@geol.umd.edu
AF: Department of Geology, University of Maryland, College Park, MD 20742-4211 United States
AU: Palardy, J E
EM: jpalardy@brown.edu
AF: Department of Earth and Environmental Science, University of Pennsylvania, Philadelphia, PA 19104-6316 United States
AB: The ratios of cadmium to calcium (Cd/Ca) and barium to calcium (Ba/Ca) chronicled in coral skeletal records are promising, yet uncalibrated, proxy tracers of oceanic upwelling. To date there has been no rigorous experimental evaluation of the natural variability of these elements among coral individuals, between species or across depth. Without an understanding of this variability, comparison of such proxy-derived records could yield inaccurate results. As a first step towards the quantitative development of these tracers, preliminary results from a survey of skeletal Cd and Ba (3 species, 2 depths, 30 individuals) will be presented, as well as stable oxygen and carbon isotopic values. {\it Pavona gigantea}, {\it Pavona clavus} and {\it Porites lobata} coral fragments were grown under monitored conditions during upwelling and non-upwelling periods in the Gulf of Panama (Pacific Ocean); the associated sea surface temperature, subsurface light intensity and nutrient concentration data will be compared to the skeletal records. Initial data from {\it P. clavus} does indicate a clear relationship between upwelling conditions and skeletal Cd/Ca. Once the range of natural variability in these fragments has been determined, the Cd/Ca and Ba/Ca ratios can then be evaluated against ocean conditions with an improved understanding of any species-specific offset or depth adjustments that should be made when comparing data sets. As quantitative upwelling proxies, coralline Cd/Ca and Ba/Ca could dramatically contribute to our understanding of the natural variability and intensity of oceanic upwelling events, and tropical climate variability on seasonal-to-centennial timescales.
DE: 4808 Chemical tracers
DE: 4875 Trace elements
DE: 4894 Instruments and techniques
DE: 4215 Climate and interannual variability (3309)
DE: 4279 Upwelling and convergences
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2004 AGU Fall Meeting