Coralline algal structure is more sensitive to rate, rather than the magnitude, of ocean acidification

• Published in: Global Change Biology
• Main Authors: Kamenos, Nicholas A., Burdett, Heidi L., Aloisio, Elena, Findlay, Helen S., Martin, Sophie, Longbone, Charlotte, Dunn, Jonathan, Widdicombe, Stephen, Calosi, Piero
• Other Authors: School of Geographical and Earth Sciences, University of Glasgow, Department of Earth Sciences St Andrews, University of St Andrews Scotland, Marine Biology and Ecology Research Centre, Plymouth University, Plymouth Marine Laboratory (PML), Ecogéochimie et Fonctionnement des Ecosystèmes Benthiques (EFEB), Adaptation et diversité en milieu marin (AD2M), Station biologique de Roscoff Roscoff (SBR), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Station biologique de Roscoff Roscoff (SBR), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Royal Society of Edinburgh / Scottish Government Fellowship RSE 48704/1, Research Councils UK Research Fellowship, Lord Kingsland Research Fellowship, Natural Environment Research Council PhD studentship NE/H525303/1, Plymouth Marine Laboratory's NERC national capability funding, Natural Environment Research Council NE/H017305/1
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2013
• Subjects: calcification; coralline algae; crustose coralline algae (CCA); maerl; ocean acidification; photosynthesis; raman; rate; respiration; rhodolith; [SDV]Life Sciences [q-bio]; [SDE]Environmental Sciences; Ocean acidification
• Online Access: https://hal.science/hal-01255955; https://hal.science/hal-01255955/document; https://hal.science/hal-01255955/file/gcb12351.pdf; https://doi.org/10.1111/gcb.12351

International audience Marine pCO(2) enrichment via ocean acidification (OA), upwelling and release from carbon capture and storage (CCS) facilities is projected to have devastating impacts on marine biomineralisers and the services they provide. However, empirical studies using stable endpoint pCO(2) concentrations find species exhibit variable biological and geochemical responses rather than the expected negative patterns. In addition, the carbonate chemistry of many marine systems is now being observed to be more variable than previously thought. To underpin more robust projections of future OA impacts on marine biomineralisers and their role in ecosystem service provision, we investigate coralline algal responses to realistically variable scenarios of marine pCO(2) enrichment. Coralline algae are important in ecosystem function; providing habitats and nursery areas, hosting high biodiversity, stabilizing reef structures and contributing to the carbon cycle. Red coralline marine algae were exposed for 80days to one of three pH treatments: (i) current pH (control); (ii) low pH (7.7) representing OA change; and (iii) an abrupt drop to low pH (7.7) representing the higher rates of pH change observed at natural vent systems, in areas of upwelling and during CCS releases. We demonstrate that red coralline algae respond differently to the rate and the magnitude of pH change induced by pCO(2) enrichment. At low pH, coralline algae survived by increasing their calcification rates. However, when the change to low pH occurred at a fast rate we detected, using Raman spectroscopy, weaknesses in the calcite skeleton, with evidence of dissolution and molecular positional disorder. This suggests that, while coralline algae will continue to calcify, they may be structurally weakened, putting at risk the ecosystem services they provide. Notwithstanding evolutionary adaptation, the ability of coralline algae to cope with OA may thus be determined primarily by the rate, rather than magnitude, at which pCO(2) enrichment occurs.