Extracting a Climate Signal from the Skeletal Geochemistry of the Caribbean Coral Siderastrea siderea

Author

Christopher Robert Maupin, University of South Florida

Graduation Year

2008

Document Type

Thesis

Degree

M.S.

Degree Granting Department

Marine Science

Major Professor

David Hollander, Ph.D.

Committee Member

Terrence M. Quinn, Ph.D.

Committee Member

Eugene A. Shinn, Ph.D.

Committee Member

Al Hine, Ph.D.

Keywords

coral geochemistry, Sr/Ca, oxygen isotopes, Dry Tortugas, paleoclimatology, paleoceanography

Abstract

The first bimonthly resolved, paired δ¹⁸O and Sr/Ca time series from the slow-growing, tropical western Atlantic coral, Siderastrea siderea, from the Dry Tortugas, Florida has been generated and used to document that robust proxy climate records can be produced from this heretofore underutilized massive coral. The coral time series contains a 20-year long calibration window (1973-1992) for both δ¹⁸O and Sr/Ca and a 73-year long verification window (1900-1972) for Sr/Ca. These time series permits both the quantification of the relationship between coral δ¹⁸O-SST and Sr/Ca-SST using an augmented, 1° x 1° gridded SST record and the assessment of the stability of the proxy relationships over time. Both coral geochemical records are highly correlated with the augmented instrumental SST record through the calibration period and Sr/Ca remains highly correlated through the verification period both at the bimonthly (r = -0.97) and annual average level (r = -0.72). Additionally, both coral δ¹⁸O and Sr/Ca are highly reproducible within the same core, and Sr/Ca exhibits no extension-related vital effects. Sr/Ca-SST anomalies are also significantly correlated to the augmented SST anomalies, despite the removal of the serial autocorrelation. The skill of this proxy demonstrates its potential as a continuously growing, long-lived recorder of climate variability for the tropical Atlantic and Intra-American Seas. The relatively slow extension rate of the coral (~5 mm yr^-1 during the 20th century) also suggests the potential for long records of climate variability (~200 years) of the region to be extracted from even modest-sized colonies (~1 m in height). The results of this study are important because relatively few century-long, sub-annually resolved time series of climate variability from massive Atlantic corals have been published, despite the significance of the tropical Atlantic climate modes of variability.

Scholar Commons Citation

Maupin, Christopher Robert, "Extracting a Climate Signal from the Skeletal Geochemistry of the Caribbean Coral Siderastrea siderea" (2008). USF Tampa Graduate Theses and Dissertations.
https://digitalcommons.usf.edu/etd/384