Arctic coralline algae elevate surface pH and carbonate in the dark

Hofmann, L. C., Schoenrock, K. and de Beer, D. (2018) Arctic coralline algae elevate surface pH and carbonate in the dark. Frontiers in Plant Science, 9, 1416. (doi: 10.3389/fpls.2018.01416) (PMID:30319676) (PMCID:PMC6167962)

Abstract

Red coralline algae are projected to be sensitive to ocean acidification, particularly in polar oceans. As important ecosystem engineers, their potential sensitivity has broad implications, and understanding their carbon acquisition mechanisms is necessary for making reliable predictions. Therefore, we investigated the localized carbonate chemistry at the surface of Arctic coralline algae using microsensors. We report for the first time carbonate ion concentration and pH measurements ([CO ]) at and above the algal surface in the microenvironment. We show that surface pH and [CO ] are higher than the bulk seawater in the light, and even after hours of darkness. We further show that three species of Arctic coralline algae have efficient carbon concentrating mechanisms including direct bicarbonate uptake and indirect bicarbonate use via a carbonic anhydrase enzyme. Our results suggest that Arctic corallines have strong biological control over their surface chemistry, where active calcification occurs, and that net dissolution in the dark does not occur. We suggest that the elevated pH and [CO ] in the dark could be explained by a high rate of light independent carbon fixation that reduces respiratory CO release. This mechanism could provide a potential adaptation to ocean acidification in Arctic coralline algae, which has important implications for future Arctic marine ecosystems.

• Item Type: Articles
• Additional Information: This research was funded by the National Science Foundation Ocean Sciences International Postdoctoral Research Fellow program awarded to Dr. L. C. Hofmann (Grant No. 1521610): “Plasticity of Inorganic Carbon Use in Marine Calcifying Macroalgae Across a Latitudinal Gradient and Consequences of Global Change.” Funding for KS to travel to and participate in this project at the Max Planck Society for Marine Microbiology was provided by a Federation of European Microbiological Societies (FEMS) Research Grant (Grant No. FEMS-RG-2015- 0111).
• Keywords: Calcification, carbon concentrating mechanism, carbonate chemistry, light-independent carbon fixation, microenvironment, microsensor, rhodolith.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Schoenrock, Dr Kathryn
• Authors: Hofmann, L. C., Schoenrock, K., and de Beer, D.
• College/School: College of Science and Engineering > School of Geographical and Earth Sciences
• Journal Name: Frontiers in Plant Science
• Publisher: Frontiers Media
• ISSN: 1664-462X
• ISSN (Online): 1664-462X
• Copyright Holders: Copyright © 2018 Hofmann, Schoenrock and de Beer
• First Published: First published in Frontiers in Plant Science 9: 1416
• Publisher Policy: Reproduced under a Creative Commons License