title: Future habitat suitability for coral reef ecosystems under global warming and ocean acidification.
abstract: Rising atmospheric CO2 concentrations are placing spatially divergent stresses on the world's tropical coral reefs through increasing ocean surface temperatures and ocean acidification. We show how these two stressors combine to alter the global habitat suitability for shallow coral reef ecosystems, using statistical Bioclimatic Envelope Models rather than basing projections on any a priori assumptions of physiological tolerances or fixed thresholds. We apply two different modeling approaches (Maximum Entropy and Boosted Regression Trees) with two levels of complexity (one a simplified and reduced environmental variable version of the other). Our models project a marked temperature-driven decline in habitat suitability for many of the most significant and bio-diverse tropical coral regions, particularly in the central Indo-Pacific. This is accompanied by a temperature-driven poleward range expansion of favorable conditions accelerating up to 40-70 km per decade by 2070. We find that ocean acidification is less influential for determining future habitat suitability than warming, and its deleterious effects are centered evenly in both hemispheres between 5° and 20° latitude. Contrary to expectations, the combined impact of ocean surface temperature rise and acidification leads to little, if any, degradation in future habitat suitability across much of the Atlantic and areas currently considered 'marginal' for tropical corals, such as the eastern Equatorial Pacific. These results are consistent with fossil evidence of range expansions during past warm periods. In addition, the simplified models are particularly sensitive to short-term temperature variations and their projections correlate well with reported locations of bleaching events. Our approach offers new insights into the relative impact of two global environmental pressures associated with rising atmospheric CO2 on potential future habitats, but greater understanding of past and current controls on coral reef ecosystems is essential to their conservation and management under a changing climate.
authors.affiliation: School of Geographical Sciences, University of Bristol, Bristol, BS8 1SS, UK; School of Earth Sciences, University of Bristol, Bristol, BS8 1RJ, UK.
authors.forename: Elena
authors.initials: E
authors.lastname: Couce
authors.forename: Andy
authors.initials: A
authors.lastname: Ridgwell
authors.forename: Erica J
authors.initials: EJ
authors.lastname: Hendy
mesh_terms: D000818:Animals; D037421:Anthozoa / Q000502:physiology*; D002245:Carbon Dioxide / Q000378:metabolism*; D057894:Coral Reefs; D005843:Geography; D057232:Global Warming; D006863:Hydrogen-Ion Concentration; D008962:Models, Theoretical; D012623:Seawater / Q000737:chemistry*
chemical_list: D002245:Carbon Dioxide
keywords: Bioclimatic Envelope Modeling; MaxEnt; boosted regression trees; coral reef ecosystems; global warming; maximum entropy; ocean acidification
references.citation: Science. 2011 Nov 4;334(6056):652-5
references.pmid: 22053045
references.citation: Science. 1999 Apr 2;284(5411):118-20
references.pmid: 10102806
references.citation: Mar Pollut Bull. 2009 Oct;58(10):1428-36
references.pmid: 19782832
references.citation: Science. 2012 Mar 2;335(6072):1058-63
references.pmid: 22383840
references.citation: Glob Chang Biol. 2013 Jan;19(1):282-90
references.pmid: 23504739
references.citation: Science. 2007 Dec 14;318(5857):1737-42
references.pmid: 18079392
references.citation: Proc Natl Acad Sci U S A. 2012 Dec 26;109(52):21378-83
references.pmid: 23236154
references.citation: Science. 2012 Feb 3;335(6068):593-6
references.pmid: 22301320
references.citation: Glob Chang Biol. 2005 Dec;11(12):2251-2265
references.pmid: 34991281
references.citation: PLoS One. 2011 Mar 29;6(3):e18038
references.pmid: 21479235
references.citation: Ecol Appl. 2009 Jan;19(1):3-17
references.pmid: 19323170
references.citation: Science. 2003 Aug 15;301(5635):929-33
references.pmid: 12920289
references.citation: Ecology. 2007 Jan;88(1):243-51
references.pmid: 17489472
references.citation: Mar Pollut Bull. 2010 Jun;60(6):787-92
references.pmid: 20538146
references.citation: Proc Natl Acad Sci U S A. 2009 Nov 17;106 Suppl 2:19729-36
references.pmid: 19822750
references.citation: Proc Natl Acad Sci U S A. 2008 Jul 29;105(30):10450-5
references.pmid: 18663220
references.citation: Glob Chang Biol. 2014 Dec;20(12):3593-4
references.pmid: 25200514
references.citation: Glob Chang Biol. 2013 Jun;19(6):1884-96
references.pmid: 23505245
references.citation: Science. 2009 Jan 2;323(5910):116-9
references.pmid: 19119230
references.citation: Ann N Y Acad Sci. 2009 Apr;1162:136-86
references.pmid: 19432648
references.citation: Proc Natl Acad Sci U S A. 2008 Nov 11;105(45):17442-6
references.pmid: 18988740
references.citation: Mar Pollut Bull. 2010 Jul;60(7):964-70
references.pmid: 20447661
references.citation: Science. 1988 Jun 3;240(4857):1285-93
references.pmid: 3287615
references.citation: Science. 2012 Jul 6;337(6090):81-4
references.pmid: 22767927
references.citation: Science. 2011 Jul 22;333(6041):418-22
references.pmid: 21778392
references.citation: Curr Biol. 2013 May 20;23(10):912-8
references.pmid: 23664976
references.citation: J Anim Ecol. 2008 Jul;77(4):802-13
references.pmid: 18397250