Interpreting sea surface temperature from strontium/calcium ratios in Montastrea corals : link with growth rate and implications for proxy reconstructions
Saenger, Casey P.
Cohen, Anne L.
Oppo, Delia W.
MetadataShow full item record
We analyzed strontium/calcium ratios (Sr/Ca) in four colonies of the Atlantic coral genus Montastrea with growth rates ranging from 2.3 to 12.6 mm a−1. Derived Sr/Ca–sea surface temperature (SST) calibrations exhibit significant differences among the four colonies that cannot be explained by variations in SST or seawater Sr/Ca. For a single coral Sr/Ca ratio of 8.8 mmol mol−1, the four calibrations predict SSTs ranging from 24.0° to 30.9°C. We find that differences in the Sr/Ca–SST relationships are correlated systematically with the average annual extension rate (ext) of each colony such that Sr/Ca (mmol mol−1) = 11.82 (±0.13) – 0.058 (±0.004) × ext (mm a−1) – 0.092 (±0.005) × SST (°C). This observation is consistent with previous reports of a link between coral Sr/Ca and growth rate. Verification of our growth-dependent Sr/Ca–SST calibration using a coral excluded from the calibration reconstructs the mean and seasonal amplitude of the actual recorded SST to within 0.3°C. Applying a traditional, nongrowth-dependent Sr/Ca–SST calibration derived from a modern Montastrea to the Sr/Ca ratios of a conspecific coral that grew during the early Little Ice Age (LIA) (400 years B.P.) suggests that Caribbean SSTs were >5°C cooler than today. Conversely, application of our growth-dependent Sr/Ca–SST calibration to Sr/Ca ratios derived from the LIA coral indicates that SSTs during the 5-year period analyzed were within error (±1.4°C) of modern values.
Author Posting. © American Geophysical Union, 2008. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Paleoceanography 23 (2008): PA3102, doi:10.1029/2007PA001572.
Showing items related by title, author, creator and subject.
Record of Little Ice Age sea surface temperatures at Bermuda using a growth-dependent calibration of coral Sr/Ca Goodkin, Nathalie F.; Hughen, Konrad A.; Cohen, Anne L.; Smith, Struan R. (American Geophysical Union, 2005-11-30)Strontium to calcium ratios (Sr/Ca) are reported for a massive brain coral Diploria labyrinthiformis collected from the south shore of Bermuda and are strongly correlated with both sea surface temperature (SST) and mean ...
Holcomb, Michael; Cohen, Anne L.; McCorkle, Daniel C. (2012-12)In situ skeletal markers have been widely used to quantify skeletal growth rates of scleractinian corals on sub-annual time-scales. Nevertheless, an evaluation of different techniques, both in terms of their efficacy and ...
Bosshart, Sara A. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2013-02)Accurate predictions of Caribbean carol reef responses to global climate change are currently limited by a lack of knowledge of the dominant environmental controls on coral growth. Corals exhibit significant responses to ...