title: Greenhouse conditions induce mineralogical changes and dolomite accumulation in coralline algae on tropical reefs.
abstract: Human-induced ocean acidification and warming alter seawater carbonate chemistry reducing the calcification of reef-building crustose coralline algae (CCA), which has implications for reef stability. However, due to the presence of multiple carbonate minerals with different solubilities in seawater, the algal mineralogical responses to changes in carbonate chemistry are poorly understood. Here we demonstrate a 200% increase in dolomite concentration in living CCA under greenhouse conditions of high pCO2 (1,225 μatm) and warming (30 °C). Aragonite, in contrast, increases with lower pCO2 (296 μatm) and low temperature (28 °C). Mineral changes in the surface pigmented skeleton are minor and dolomite and aragonite formation largely occurs in the white crust beneath. Dissolution of high-Mg-calcite and particularly the erosive activities of endolithic algae living inside skeletons play key roles in concentrating dolomite in greenhouse treatments. As oceans acidify and warm in the future, the relative abundance of dolomite in CCA will increase.
authors: Griffith School of Environment, Australian Rivers Institute-Coast and Estuaries, and Australian Research Council Centre of Excellence for Coral Reef Studies, Nathan Campus, Griffith University, 170 Kessels Road, Brisbane, Nathan, Queensland 4111, Australia.
authors: Guillermo
authors: G
authors: Diaz-Pulido
authors: Research School of Physics, The Australian National University, Acton, Australian Capital Territory 0200, Australia.
authors: Merinda C
authors: MC
authors: Nash
authors: Australian Institute of Marine Science, Townsville, Queensland 4810, Australia.
authors: Kenneth R N
authors: KR
authors: Anthony
authors: Global Change Institute and Australian Research Council Centre of Excellence for Coral Reef Studies, The University of Queensland, St Lucia, Brisbane, Queensland 4072, Australia.
authors: Dorothea
authors: D
authors: Bender
authors: Research School of Earth Sciences, The Australian National University, Acton, Australian Capital Territory 0200, Australia.
authors: Bradley N
authors: BN
authors: Opdyke
authors: Global Change Institute and Australian Research Council Centre of Excellence for Coral Reef Studies, The University of Queensland, St Lucia, Brisbane, Queensland 4072, Australia.
authors: Catalina
authors: C
authors: Reyes-Nivia
authors: Research School of Earth Sciences, The Australian National University, Acton, Australian Capital Territory 0200, Australia.
authors: Ulrike
authors: U
authors: Troitzsch
mesh_terms: D002119:Calcium Carbonate / Q000737:chemistry*; D057894:Coral Reefs; D008274:Magnesium / Q000737:chemistry*; D009792:Oceans and Seas; D012623:Seawater / Q000737:chemistry
chemical_list: D002119:Calcium Carbonate; D008274:Magnesium; C028042:calcium magnesium carbonate