title: Coral calcifying fluid pH is modulated by seawater carbonate chemistry not solely seawater pH.
abstract: Reef coral calcification depends on regulation of pH in the internal calcifying fluid (CF) in which the coral skeleton forms. However, little is known about calcifying fluid pH (pHCF) regulation, despite its importance in determining the response of corals to ocean acidification. Here, we investigate pHCFin the coral Stylophora pistillata in seawater maintained at constant pH with manipulated carbonate chemistry to alter dissolved inorganic carbon (DIC) concentration, and therefore total alkalinity (AT). We also investigate the intracellular pH of calcifying cells, photosynthesis, respiration and calcification rates under the same conditions. Our results show that despite constant pH in the surrounding seawater, pHCFis sensitive to shifts in carbonate chemistry associated with changes in [DIC] and [AT], revealing that seawater pH is not the sole driver of pHCFNotably, when we synthesize our results with published data, we identify linear relationships of pHCFwith the seawater [DIC]/[H+] ratio, [AT]/ [H+] ratio and [[Formula: see text]]. Our findings contribute new insights into the mechanisms determining the sensitivity of coral calcification to changes in seawater carbonate chemistry, which are needed for predicting effects of environmental change on coral reefs and for robust interpretations of isotopic palaeoenvironmental records in coral skeletons.
authors.affiliation: Department of Biology, California State University, 18111 Nordhoff Street, Northridge, CA 91330-8303, USA steeve.comeau@uwa.edu.au.|School of Earth and Environment and ARC Centre of Excellence for Coral Reef Studies, The University of Western Australia, Crawley, Western Australia 6009, Australia.
authors.forename: S
authors.identifier: 0000-0002-6724-5286
authors.initials: S
authors.lastname: Comeau
authors.affiliation: Marine Biology Department, Centre Scientifique de Monaco, 8 Quai Antoine 1er, MC98000, Monaco.|Laboratoire International Associé 647 «BIOSENSIB», Centre Scientifique de Monaco-Centre National de la Recherche Scientifique, 8 Quai Antoine 1er, MC98000, Monaco.
authors.forename: E
authors.initials: E
authors.lastname: Tambutté
authors.affiliation: Department of Biology, California State University, 18111 Nordhoff Street, Northridge, CA 91330-8303, USA.
authors.forename: R C
authors.initials: RC
authors.lastname: Carpenter
authors.affiliation: Department of Biology, California State University, 18111 Nordhoff Street, Northridge, CA 91330-8303, USA.
authors.forename: P J
authors.initials: PJ
authors.lastname: Edmunds
authors.affiliation: Department of Biology, California State University, 18111 Nordhoff Street, Northridge, CA 91330-8303, USA.|Marine Spatial Ecology Lab, ARC Centre of Excellence for Coral Reef Studies and School of Biological Sciences, The University of Queensland, St Lucia, Queensland 4072, Australia.
authors.forename: N R
authors.initials: NR
authors.lastname: Evensen
authors.affiliation: Marine Biology Department, Centre Scientifique de Monaco, 8 Quai Antoine 1er, MC98000, Monaco.|Laboratoire International Associé 647 «BIOSENSIB», Centre Scientifique de Monaco-Centre National de la Recherche Scientifique, 8 Quai Antoine 1er, MC98000, Monaco.
authors.forename: D
authors.initials: D
authors.lastname: Allemand
authors.affiliation: Marine Biology Department, Centre Scientifique de Monaco, 8 Quai Antoine 1er, MC98000, Monaco.|Laboratoire International Associé 647 «BIOSENSIB», Centre Scientifique de Monaco-Centre National de la Recherche Scientifique, 8 Quai Antoine 1er, MC98000, Monaco.
authors.forename: C
authors.initials: C
authors.lastname: Ferrier-Pagès
authors.affiliation: Marine Biology Department, Centre Scientifique de Monaco, 8 Quai Antoine 1er, MC98000, Monaco.|Laboratoire International Associé 647 «BIOSENSIB», Centre Scientifique de Monaco-Centre National de la Recherche Scientifique, 8 Quai Antoine 1er, MC98000, Monaco.
authors.forename: S
authors.initials: S
authors.lastname: Tambutté
authors.affiliation: Marine Biology Department, Centre Scientifique de Monaco, 8 Quai Antoine 1er, MC98000, Monaco avenn@centrescientifique.mc.|Laboratoire International Associé 647 «BIOSENSIB», Centre Scientifique de Monaco-Centre National de la Recherche Scientifique, 8 Quai Antoine 1er, MC98000, Monaco.
authors.forename: A A
authors.initials: AA
authors.lastname: Venn
mesh_terms: D000818:Animals; D037421:Anthozoa / Q000502:physiology*; D002113:Calcification, Physiologic; D002254:Carbonates / Q000737:chemistry*; D057894:Coral Reefs; D006863:Hydrogen-Ion Concentration; D012623:Seawater / Q000737:chemistry*
chemical_list: D002254:Carbonates
keywords: calcification; dissolved inorganic carbon; ocean acidification; protons; total alkalinity