HR: 0800h
AN: GC51A-0161    [Abstracts]
TI: Return Periods of Anomalous Sea-Surface Temperature Events Inferred From Wavelet Analysis of Thermal Proxy Records in Corals: Implications for Coral Bleaching
AU: * Thompson, D M
EM: dthompso@fit.edu
AF: Florida Institute of Technology, Department of Biological Sciences, 150 W. University Blvd., Melbourne, FL 32901, United States
AU: van Woesik, R
EM: rvw@fit.edu
AF: Florida Institute of Technology, Department of Biological Sciences, 150 W. University Blvd., Melbourne, FL 32901, United States
AB: Coral populations are highly responsive to thermal stress, often resulting in considerable bleaching and subsequent mortality. Tolerance and adjustment to thermal stress are considered a consequence of the host- symbiont constitution and their thermal history. Since the frequency, severity and spatial scale of anomalously high sea-surface temperatures have increased in the past three decades, it is necessary to determine the return periods of anomalous temperatures in the past in order to ascertain the timescales to which corals have become accustomed. We test the hypothesis that more frequent thermal anomalies in the past have led to selective pressures culminating in more tolerant contemporary coral populations. Wavelet analysis was undertaken on stable oxygen isotope records extracted from modern corals at 17 locations to determine the significant return periods of anomalous sea-surface temperatures across time in the tropical to sub-tropical Pacific, Indian and Atlantic Oceans and Red Sea. Interpolation of the significant return periods was used to determine the spatial extent of ocean-wide modes of temperature variability in the Indian and Pacific Oceans. Considerable spatial and temporal variability was apparent in the strength of the interannual and decadal components dating back over 300 years. Interannual variability was high in the far western and central to eastern Pacific and at the two poles of the Indian Ocean Dipole, but weak throughout the remainder of the Indian Ocean. Decadal variability was considerable throughout most of the Pacific Ocean, but absent in the southwest Pacific, suggesting little decadal variability in the South Pacific Convergence Zone. Decadal variability was also apparent at the poles of the Indian Ocean Dipole and in the Agulhas outflow zone. Analysis of bleaching severity within the Indian and Pacific Oceans during the 1997-1998 bleaching event revealed that bleaching was less severe at sites with a high probability of interannual variability and a low probability of decadal variability. This suggests that corals at sites that have experienced frequent thermal events in the past may be more likely to resist bleaching during future global climate change-associated anomalies.
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 3252 Spatial analysis (0500)
DE: 3280 Wavelet transform (3255, 4455)
DE: 3344 Paleoclimatology (0473, 4900)
DE: 4220 Coral reef systems (4916)
SC: Global Environmental Change [GC]
MN: 2007 Fall Meeting