title: BEFORE OCEAN ACIDIFICATION: CALCIFIER CHEMISTRY LESSONS(1).
abstract: Ocean Acidification (OA) has been an important research topic for a decade. Scientists have focused on how the predicted 56% decline in the seawater carbonate ion () concentration will dramatically impair the ability of calcifiers, ranging from coccolithophores to shellfish, to form calcium carbonate (CaCO3 ) structures, and the implications of the reduced carbonate saturation state (Ω) for increased dissolution of such structures. However, many published OA studies have overlooked a fundamental issue: most calcifying organisms do not rely on carbonate from seawater to calcify; they use either bicarbonate () or metabolically-produced CO2 . The ability of important primary (corals, coralline seaweeds, and coccolithophores) and secondary (mollusks) producers to modify their local carbonate chemistry suggests that the primary threat to them from OA is by dissolution rather than impaired calcification. Here, we draw on calcification research from an era before OA and combine it with recent studies that question the source of the carbonate ion, to provide new insights into how OA might affect calcifying organisms. Organismal modification of local carbonate chemistry may enable some calcifiers to successfully form calcareous structures despite OA.
authors.affiliation: Department of Botany, University of Otago, P.O. Box 56, Dunedin 9054, New ZealandNIWA Centre for Chemical and Physical Oceanography, Department of Chemistry, University of Otago, Dunedin 9012, New ZealandDepartment of Botany, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand.
authors.forename: Michael Y
authors.initials: MY
authors.lastname: Roleda
authors.affiliation: Department of Botany, University of Otago, P.O. Box 56, Dunedin 9054, New ZealandNIWA Centre for Chemical and Physical Oceanography, Department of Chemistry, University of Otago, Dunedin 9012, New ZealandDepartment of Botany, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand.
authors.forename: Philip W
authors.initials: PW
authors.lastname: Boyd
authors.affiliation: Department of Botany, University of Otago, P.O. Box 56, Dunedin 9054, New ZealandNIWA Centre for Chemical and Physical Oceanography, Department of Chemistry, University of Otago, Dunedin 9012, New ZealandDepartment of Botany, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand.
authors.forename: Catriona L
authors.initials: CL
authors.lastname: Hurd
keywords: calcification; carbonate chemistry; carbonic anhydrase; coccolithophores; coralline macroalgae; corals; invertebrate; molluscs; ocean acidification; physiological chemistry