title: Ocean acidification causes structural deformities in juvenile coral skeletons.
abstract: Rising atmospheric CO2 is causing the oceans to both warm and acidify, which could reduce the calcification rates of corals globally. Successful coral recruitment and high rates of juvenile calcification are critical to the replenishment and ultimate viability of coral reef ecosystems. Although elevated Pco2 (partial pressure of CO2) has been shown to reduce the skeletal weight of coral recruits, the structural changes caused by acidification during initial skeletal deposition are unknown. We show, using high-resolution three-dimensional x-ray microscopy, that ocean acidification (Pco2 ~900 μatm, pH ~7.7) not only causes reduced overall mineral deposition but also a deformed and porous skeletal structure in newly settled coral recruits. In contrast, elevated temperature (+3°C) had little effect on skeletal formation except to partially mitigate the effects of elevated Pco2. The striking structural deformities we observed show that new recruits are at significant risk, being unable to effectively build their skeletons in the Pco2 conditions predicted to occur for open ocean surface waters under a "business-as-usual" emissions scenario [RCP (representative concentration pathway) 8.5] by the year 2100.
authors.affiliation: UWA School of Earth and Environment, University of Western Australia, Crawley, Western Australia 6009, Australia.; UWA Oceans Institute, University of Western Australia, Crawley, Western Australia 6009, Australia.; ARC Centre of Excellence for Coral Reef Studies, University of Western Australia, Crawley, Western Australia 6009, Australia.
authors.forename: Taryn
authors.initials: T
authors.lastname: Foster
authors.affiliation: UWA School of Earth and Environment, University of Western Australia, Crawley, Western Australia 6009, Australia.; UWA Oceans Institute, University of Western Australia, Crawley, Western Australia 6009, Australia.; ARC Centre of Excellence for Coral Reef Studies, University of Western Australia, Crawley, Western Australia 6009, Australia.
authors.forename: James L
authors.identifier: 0000-0001-6211-7018
authors.initials: JL
authors.lastname: Falter
authors.affiliation: UWA School of Earth and Environment, University of Western Australia, Crawley, Western Australia 6009, Australia.; UWA Oceans Institute, University of Western Australia, Crawley, Western Australia 6009, Australia.; ARC Centre of Excellence for Coral Reef Studies, University of Western Australia, Crawley, Western Australia 6009, Australia.
authors.forename: Malcolm T
authors.identifier: 0000-0003-1538-1558
authors.initials: MT
authors.lastname: McCulloch
authors.affiliation: UWA Oceans Institute, University of Western Australia, Crawley, Western Australia 6009, Australia.; Centre for Microscopy, Characterisation and Analysis, University of Western Australia, Crawley, Western Australia 6009, Australia.
authors.forename: Peta L
authors.identifier: 0000-0002-5188-4737
authors.initials: PL
authors.lastname: Clode
mesh_terms: D000143:Acids / Q000737:chemistry; D000818:Animals; D037421:Anthozoa / Q000033:anatomy & histology* / Q000254:growth & development / Q000378:metabolism*; D002113:Calcification, Physiologic; D002245:Carbon Dioxide / Q000032:analysis; D057894:Coral Reefs; D017753:Ecosystem; D006863:Hydrogen-Ion Concentration; D008855:Microscopy, Electron, Scanning; D009792:Oceans and Seas; D012623:Seawater / Q000737:chemistry; D013696:Temperature
chemical_list: D000143:Acids; D002245:Carbon Dioxide
keywords: 3D x-ray microscopy, subtropical; Houtman Abrolhos Islands; Ocean acidification; PCO2; asymmetry; coral calcification; juvenile skeleton; porous; structural deformities; temperature