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Intrareef variations in Li/Mg and Sr/Ca sea surface temperature proxies in the Caribbean reef-building coral Siderastrea siderea: Intrareef Variations in SST Proxies

Intrareef variations in Li/Mg and Sr/Ca sea surface temperature proxies in the Caribbean reef-building coral Siderastrea siderea: Intrareef Variations in SST Proxies
Intrareef variations in Li/Mg and Sr/Ca sea surface temperature proxies in the Caribbean reef-building coral Siderastrea siderea: Intrareef Variations in SST Proxies
Caribbean sea surface temperatures (SSTs) have increased at a rate of 0.2°C per decade since 1971, a rate double that of the mean global change. Recent investigations of the coral Siderastrea siderea on the Belize Mesoamerican Barrier Reef System (MBRS) have demonstrated that warming over the last 30 years has had a detrimental impact on calcification. Instrumental temperature records in this region are sparse, making it necessary to reconstruct longer SST records indirectly through geochemical temperature proxies. Here we investigate the skeletal Sr/Ca and Li/Mg ratios of S. siderea from two distinct reef zones (forereef and backreef) of the MBRS. Our field calibrations of S. siderea show that Li/Mg and Sr/Ca ratios are well correlated with temperature, although both ratios are 3 times more sensitive to temperature change in the forereef than in the backreef. These differences suggest that a secondary parameter also influences these SST proxies, highlighting the importance for site- and species-specific SST calibrations. Application of these paleothermometers to downcore samples reveals highly uncertain reconstructed temperatures in backreef coral, but well-matched reconstructed temperatures in forereef coral, both between Sr/Ca-SSTs and Li/Mg-SSTs, and in comparison to the Hadley Centre Sea Ice and Sea Surface Temperature record. Reconstructions generated from a combined Sr/Ca and Li/Mg multiproxy calibration improve the precision of these SST reconstructions. This result confirms that there are circumstances in which both Li/Mg and Sr/Ca are reliable as stand-alone and combined proxies of sea surface temperature. However, the results also highlight that high-precision, site-specific calibrations remain critical for reconstructing accurate SSTs from coral-based elemental proxies.
0883-8305
1315-1329
Fowell, Sara, Elisabeth
04bb3910-4057-4a1a-89bb-701c5c0782eb
Sandford, Kate
a408ac1e-779c-437e-9745-776e4a6b0171
Stewart, Joseph A.
3d7f8398-d59b-458b-a3c9-e6a54d87e9b1
Castillo, Karl D.
39eeae7b-a375-4224-b962-94901e9e0cf8
Ries, Justin B.
e7b09c48-88cf-49ae-8eb2-f1a2f54c2449
Foster, Gavin L.
fbaa7255-7267-4443-a55e-e2a791213022
Fowell, Sara, Elisabeth
04bb3910-4057-4a1a-89bb-701c5c0782eb
Sandford, Kate
a408ac1e-779c-437e-9745-776e4a6b0171
Stewart, Joseph A.
3d7f8398-d59b-458b-a3c9-e6a54d87e9b1
Castillo, Karl D.
39eeae7b-a375-4224-b962-94901e9e0cf8
Ries, Justin B.
e7b09c48-88cf-49ae-8eb2-f1a2f54c2449
Foster, Gavin L.
fbaa7255-7267-4443-a55e-e2a791213022

Fowell, Sara, Elisabeth, Sandford, Kate, Stewart, Joseph A., Castillo, Karl D., Ries, Justin B. and Foster, Gavin L. (2016) Intrareef variations in Li/Mg and Sr/Ca sea surface temperature proxies in the Caribbean reef-building coral Siderastrea siderea: Intrareef Variations in SST Proxies. Paleoceanography, 31 (10), 1315-1329. (doi:10.1002/palo.v31.10).

Record type: Article

Abstract

Caribbean sea surface temperatures (SSTs) have increased at a rate of 0.2°C per decade since 1971, a rate double that of the mean global change. Recent investigations of the coral Siderastrea siderea on the Belize Mesoamerican Barrier Reef System (MBRS) have demonstrated that warming over the last 30 years has had a detrimental impact on calcification. Instrumental temperature records in this region are sparse, making it necessary to reconstruct longer SST records indirectly through geochemical temperature proxies. Here we investigate the skeletal Sr/Ca and Li/Mg ratios of S. siderea from two distinct reef zones (forereef and backreef) of the MBRS. Our field calibrations of S. siderea show that Li/Mg and Sr/Ca ratios are well correlated with temperature, although both ratios are 3 times more sensitive to temperature change in the forereef than in the backreef. These differences suggest that a secondary parameter also influences these SST proxies, highlighting the importance for site- and species-specific SST calibrations. Application of these paleothermometers to downcore samples reveals highly uncertain reconstructed temperatures in backreef coral, but well-matched reconstructed temperatures in forereef coral, both between Sr/Ca-SSTs and Li/Mg-SSTs, and in comparison to the Hadley Centre Sea Ice and Sea Surface Temperature record. Reconstructions generated from a combined Sr/Ca and Li/Mg multiproxy calibration improve the precision of these SST reconstructions. This result confirms that there are circumstances in which both Li/Mg and Sr/Ca are reliable as stand-alone and combined proxies of sea surface temperature. However, the results also highlight that high-precision, site-specific calibrations remain critical for reconstructing accurate SSTs from coral-based elemental proxies.

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More information

Accepted/In Press date: 15 September 2016
e-pub ahead of print date: 5 October 2016
Published date: October 2016
Organisations: Ocean and Earth Science, National Oceanography Centre

Identifiers

Local EPrints ID: 406413
URI: http://eprints.soton.ac.uk/id/eprint/406413
ISSN: 0883-8305
PURE UUID: 9a48a819-6bd6-446d-9c78-7a520b8cdc30
ORCID for Gavin L. Foster: ORCID iD orcid.org/0000-0003-3688-9668

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Date deposited: 10 Mar 2017 10:46
Last modified: 28 Jan 2022 02:42

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Contributors

Author: Sara, Elisabeth Fowell
Author: Kate Sandford
Author: Joseph A. Stewart
Author: Karl D. Castillo
Author: Justin B. Ries
Author: Gavin L. Foster ORCID iD

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