High-resolution Sr/Ca ratios in a Porites lutea coral from Lakshadweep Archipelago, southeast Arabian Sea: An example from a region experiencing steady rise in the reef temperature.

Sagar, Netramani, Hetzinger, Steffen, Pfeiffer, Miriam, Masood Ahmad, Syed, Dullo, Wolf-Christian and Garbe-Schönberg, Dieter (2016) High-resolution Sr/Ca ratios in a Porites lutea coral from Lakshadweep Archipelago, southeast Arabian Sea: An example from a region experiencing steady rise in the reef temperature. Open Access Journal of Geophysical Research: Oceans, 121 (1). pp. 252-266. DOI 10.1002/2015JC010821.

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Abstract

Here we present the first record of Sr/Ca variability in a massive Porites lutea coral from the Lakshadweep Archipelago, Arabian Sea. The annual mean sea surface temperature (SST) in this region and the surrounding areas has increased steadily in the recent past. During some major El Nino events, SSTs are even higher, imposing additional thermal-stress on corals, episodically leading to coral bleaching. We infer from the coral-Sr/Ca record (1981-2008) that during some of these events high and persistent SSTs lead to a dampening of the temperature signal in coral-Sr/Ca, impairing the coral's ability to record full scale warming. Thus, coral-Sr/Ca may provide a history of past El Nino Southern-Oscillation (ENSO) induced thermal-stress episodes, which are a recurrent feature also seen in cross-spectral analysis between coral-Sr/Ca and the Nino3.4 index. Despite the impact of episodical thermal-stress during major El Nino events, our coral proxy faithfully records the seasonal monsoon-induced summer cooling on the order of approximate to 2.3 degrees C. Calibration of coral-Sr/Ca with instrumental grid-SST data shows significant correlation to regional SST and monsoon variability. Hence, massive Porites corals of this region are highly valuable archives for reconstructing long-term changes in SST, strongly influenced by monsoon variability on seasonal scales. More importantly, our data show that this site with increasing SST is an ideal location for testing the future effects of the projected anthropogenic SST increase on coral reefs that are already under thermal-stress worldwide.

Document Type: Article
Additional Information: WOS:000371432200016
Keywords: Coral-Sr/Ca records, Lakshadweep Archipelago, southeast Arabian Sea; monsoon-induced summer temperature cooling; Arabian Sea SST; El Nino Southern-Oscillation; Porites lutea Sr; Ca ratios; SW monsoon recorded by coral; thermal stress
Research affiliation: OceanRep > The Future Ocean - Cluster of Excellence > FO-R09
OceanRep > The Future Ocean - Cluster of Excellence
OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-P-OZ Paleo-Oceanography
Kiel University
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1002/2015JC010821
ISSN: 2169-9275
Projects: INDIAS IDEA, INDEX, Future Ocean
Date Deposited: 14 Dec 2015 13:42
Last Modified: 04 Apr 2019 13:23
URI: http://oceanrep.geomar.de/id/eprint/30542

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