Abstract
High-resolution proxy records of climate are limited and have poor coverage of the tropical ocean-atmosphere system. One particular area in which climate records are lacking is the northern Gulf of Mexico. Four coral cores were collected for measurement of extension, density, and isotopes ([]¹⁸O, []¹³C). The coral oxygen isotope signature was calibrated against high-resolution daily temperature and salinity data sets spanning 1990-1997. Coralline estimates of water temperature demonstrate only ~60% of the amplitude of the actual temperature range and are offset by >15°C. The amplitude reduction appears to be the result of sampling resolution in conjunction with the manner in which these corals precipitate skeletal CaCO₃. The net effect of annual skeletal extension upon the []¹⁸O isotopic signature was examined and there appears to be no relationship between summer []¹⁸O values and extension rate. However, there is a statistically significant relationship between winter []¹⁸O values and extension rate, indicating that faster coral growth leads to a higher resolution []¹⁸O temperature signal. The values of []¹⁸O lag []¹³C by about two months, coinciding well with maxima in insolation and water temperature. Overall, these corals prove to be reliable indicators of temperature change in this region.
Smith, Jennifer Mae (2001). Temperature calibration of Gulf of Mexico corals. Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -2001 -THESIS -S642.