USGS Open-File Report 2013–1092 - Complexity of Nearshore Strontium-to-Calcium Ratio Variability in a Core Sample of the Massive Coral Siderastrea siderea Obtained in Coral Bay, St. John, U.S. Virgin Islands

Complexity of Nearshore Strontium-to-Calcium Ratio Variability in a Core Sample of the Massive Coral Siderastrea siderea Obtained in Coral Bay, St. John, U.S. Virgin Islands

By Christopher D. Reich, Ilsa B. Kuffner, T. Don Hickey, Jennifer M. Morrison, and Jennifer A. Flannery

Abstract

Strontium-to-calcium ratios (Sr/Ca) were measured on the skeletal matrix of a core sample from a colony of the massive coral Siderastrea siderea collected in Coral Bay, St. John, U.S. Virgin Islands. Strontium and calcium are incorporated into the coral skeleton during the precipitation of aragonite by the coral polyps and their ratio is highly temperature dependent. The robustness of this temperature dependence makes Sr/Ca a reliable proxy for sea surface temperature (SST). Details presented from the St. John S. siderea core indicate that terrestrial inputs of sediment and freshwater can disrupt the chemical balance and subsequently complicate the utility of Sr/Ca in reconstructing historical SST. An approximately 44-year-long record of Sr/Ca shows that an annual SST signal is recorded but with an increasing Sr/Ca trend from 1980 to present, which is likely the result of runoff from the mountainous terrain of St. John. The overwhelming influence of the terrestrial fingerprint on local seawater chemistry makes utilizing Sr/Ca as a SST proxy in nearshore environments very difficult.

First posted April 22, 2013

Report PDF (1.25 MB)

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Suggested citation:

Reich, C.D., Kuffner, I.B., Hickey, T.D., Morrison, J.M., and Flannery, J.A., 2013, Complexity of nearshore strontium-to-calcium ratio variability in a core sample of the massive coral Siderastrea siderea obtained in Coral Bay, St. John, U.S. Virgin Islands: U.S. Geological Survey Open-File Report 2013–1092, 12 p., available online only at http://pubs.usgs.gov/of/2013/1092.

Contents

Abstract

Introduction

Setting

Methods

Results and Summary

Acknowledgments

References Cited