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Ocean acidification affects coral growth by reducing skeletal density

Ocean acidification affects coral growth by reducing skeletal density
Ocean acidification affects coral growth by reducing skeletal density
Ocean acidification (OA) is considered an important threat to coral reef ecosystems, because it reduces the availability of carbonate ions that reef-building corals need to produce their skeletons. However, while theory predicts that coral calcification rates decline as carbonate ion concentrations decrease, this prediction is not consistently borne out in laboratory manipulation experiments or in studies of corals inhabiting naturally low-pH reefs today. The skeletal growth of corals consists of two distinct processes: extension (upward growth) and densification (lateral thickening). Here, we show that skeletal density is directly sensitive to changes in seawater carbonate ion concentration and thus, to OA, whereas extension is not. We present a numerical model of Porites skeletal growth that links skeletal density with the external seawater environment via its influence on the chemistry of coral calcifying fluid. We validate the model using existing coral skeletal datasets from six Porites species collected across five reef sites and use this framework to project the impact of 21st century OA on Porites skeletal density across the global tropics. Our model predicts that OA alone will drive up to 20.3 ± 5.4% decline in the skeletal density of reef-building Porites corals.
0027-8424
1754-1759
Mollica, Nathaniel R.
2db5c231-5199-4f8e-8c92-cc2e3adbdd3c
Guo, Weifu
00f4df2f-1d1f-4e55-b10f-3573d9f7cf2d
Cohen, Anne L.
b20be412-6349-4bc6-85c1-e5d5a3aafdcf
Huang, Kuo-fang
fb6f7fda-2ff5-47b0-aee6-c7eb0fcb2535
Foster, Gavin L.
fbaa7255-7267-4443-a55e-e2a791213022
Donald, Hannah K.
7314286d-9494-4a9f-a1d0-e46b632d1411
Solow, Andrew R.
94d8c9f6-f866-4fb9-9e47-d1e251913b8c
Mollica, Nathaniel R.
2db5c231-5199-4f8e-8c92-cc2e3adbdd3c
Guo, Weifu
00f4df2f-1d1f-4e55-b10f-3573d9f7cf2d
Cohen, Anne L.
b20be412-6349-4bc6-85c1-e5d5a3aafdcf
Huang, Kuo-fang
fb6f7fda-2ff5-47b0-aee6-c7eb0fcb2535
Foster, Gavin L.
fbaa7255-7267-4443-a55e-e2a791213022
Donald, Hannah K.
7314286d-9494-4a9f-a1d0-e46b632d1411
Solow, Andrew R.
94d8c9f6-f866-4fb9-9e47-d1e251913b8c

Mollica, Nathaniel R., Guo, Weifu, Cohen, Anne L., Huang, Kuo-fang, Foster, Gavin L., Donald, Hannah K. and Solow, Andrew R. (2018) Ocean acidification affects coral growth by reducing skeletal density. Proceedings of the National Academy of Sciences, 115 (8), 1754-1759. (doi:10.1073/pnas.1712806115).

Record type: Article

Abstract

Ocean acidification (OA) is considered an important threat to coral reef ecosystems, because it reduces the availability of carbonate ions that reef-building corals need to produce their skeletons. However, while theory predicts that coral calcification rates decline as carbonate ion concentrations decrease, this prediction is not consistently borne out in laboratory manipulation experiments or in studies of corals inhabiting naturally low-pH reefs today. The skeletal growth of corals consists of two distinct processes: extension (upward growth) and densification (lateral thickening). Here, we show that skeletal density is directly sensitive to changes in seawater carbonate ion concentration and thus, to OA, whereas extension is not. We present a numerical model of Porites skeletal growth that links skeletal density with the external seawater environment via its influence on the chemistry of coral calcifying fluid. We validate the model using existing coral skeletal datasets from six Porites species collected across five reef sites and use this framework to project the impact of 21st century OA on Porites skeletal density across the global tropics. Our model predicts that OA alone will drive up to 20.3 ± 5.4% decline in the skeletal density of reef-building Porites corals.

Text Mollica_et_al_2018_PNAS - Accepted Manuscript
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Accepted/In Press date: 11 December 2017
e-pub ahead of print date: 29 January 2018
Published date: February 2018

Identifiers

Local EPrints ID: 417521
URI: https://eprints.soton.ac.uk/id/eprint/417521
ISSN: 0027-8424
PURE UUID: 90eac2bf-7022-436e-a5d9-58aa107d79bc

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Date deposited: 02 Feb 2018 17:30
Last modified: 02 May 2018 04:01

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Contributors

Author: Nathaniel R. Mollica
Author: Weifu Guo
Author: Anne L. Cohen
Author: Kuo-fang Huang
Author: Gavin L. Foster
Author: Hannah K. Donald
Author: Andrew R. Solow

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