HR: 0800h
AN: PP51A-0579    [Abstracts]
TI: Variability of past Caribbean sea surface conditions derived from a century-long coral record
AU: * Hetzinger, S
EM: shetzinger@ifm-geomar.de
AF: IFM-GEOMAR, Leibniz-Institut fuer Meereswissenschaften, Wischhofstr. 1-3, Kiel, 24148 Germany
AU: Pfeiffer, M
EM:
AF: IFM-GEOMAR, Leibniz-Institut fuer Meereswissenschaften, Wischhofstr. 1-3, Kiel, 24148 Germany
AU: Dullo, W
EM:
AF: IFM-GEOMAR, Leibniz-Institut fuer Meereswissenschaften, Wischhofstr. 1-3, Kiel, 24148 Germany
AU: Ruprecht, E
EM:
AF: IFM-GEOMAR, Leibniz-Institut fuer Meereswissenschaften, Wischhofstr. 1-3, Kiel, 24148 Germany
AB: We present a 102-year-long high resolution record of coral aragonite Sr/Ca and δ¹⁸O variations from a colony of the massive reef-building coral Diploria strigosa from Guadeloupe, Lesser Antilles. Both proxies were measured at the same subsamples of coral aragonite and analyzed in monthly resolution for the growth period between 1898 and 2000. In order to deconvolve the effects of sea surface temperature (SST) and seawater oxygen isotopic composition (δ¹⁸O_sw) in the coral δ¹⁸O timeseries, we subtracted the temperature contribution inferred from coral Sr/Ca. The Sr/Ca-ratio, which is believed to reflect sea surface temperature only, was correlated with instrumental SSTs (ERSSTv.2, Smith and Reynolds 2004) for a corresponding time period (1950-2000) to derive a Sr/Ca-SST calibration. Our preliminary results indicate that monthly resolved Sr/Ca-variations in coral aragonite of Diploria strigosa, in contrast to other massive growing coral species sampled in the tropical Atlantic, capture the full amplitude of the seasonal SST cycle. Furthermore, our Sr/Ca-timeseries points to a significant rise of surface water temperature during the last two decades. The coral δ¹⁸O, in opposition, shows a larger seasonal amplitude (approx. 0.2 ‰) than expected from SST alone, owing to the considerable seasonal salinity change. Therefore, δ¹⁸O_sw reconstructed from the coral, which in turn covaries with salinity, should provide a record of past changes in the hydrologic balance. A shift towards lower δ¹⁸O values beginning in the mid-80's is observable. July-September tropical Atlantic SSTs are known to be highly correlated with the PDI (power dissipation index), which is a measure of the total power dissipated annually by tropical cyclones in the North Atlantic. The PDI and therewith hurricane intensity increased markedly during the last two decades. Both of our proxy timeseries show a strong relationship with July-September SST in the tropical North Atlantic and corroborate the strong warming since the mid-80's. A further goal of our studies will be the development of a century-long master chronology including several coral-based proxy timeseries from different coral colonies and sites in the Caribbean Sea. The master chronology will improve the signal to noise ratio compared to the single core reconstructions.
DE: 4800 OCEANOGRAPHY: BIOLOGICAL AND CHEMICAL (0460)
DE: 4870 Stable isotopes (0454, 1041)
DE: 4875 Trace elements (0489)
DE: 4916 Corals (4220)
DE: 4954 Sea surface temperature
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005