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The role of irradiance and C-use strategies in tropical macroalgae photosynthetic response to ocean acidification

Fleshy macroalgae may increase photosynthesis with greater CO(2) availability under ocean acidification (OA) and outcompete calcifying macroalgae important for tropical reef accretion. Macroalgae use energy-dependent carbon concentrating mechanisms (CCMs) to take up HCO(3)(−), the dominant inorganic...

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Autores principales: Zweng, Regina C., Koch, Marguerite S., Bowes, George
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Nature Publishing Group UK 2018
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6013460/
https://www.ncbi.nlm.nih.gov/pubmed/29930306
http://dx.doi.org/10.1038/s41598-018-27333-0
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author Zweng, Regina C.
Koch, Marguerite S.
Bowes, George
author_facet Zweng, Regina C.
Koch, Marguerite S.
Bowes, George
author_sort Zweng, Regina C.
collection PubMed
description Fleshy macroalgae may increase photosynthesis with greater CO(2) availability under ocean acidification (OA) and outcompete calcifying macroalgae important for tropical reef accretion. Macroalgae use energy-dependent carbon concentrating mechanisms (CCMs) to take up HCO(3)(−), the dominant inorganic carbon for marine photosynthesis, but carbon-use strategies may depend on the pCO(2), pH and irradiance. We examined photosynthesis in eight tropical macroalgae across a range of irradiances (0–1200 μmol photon m(−2) s(−1)), pH levels (7.5–8.5) and CO(2) concentrations (3–43 μmol kg(−1)). Species-specific CCM strategies were assessed using inhibitors and δ(13)C isotope signatures. Our results indicate that the log of irradiance is a predictor of the photosynthetic response to elevated pCO(2) (R(2) > 0.95). All species utilized HCO(3)(−), exhibited diverse C-use pathways and demonstrated facultative HCO(3)(−) use. All fleshy species had positive photosynthetic responses to OA, in contrast to a split amongst calcifiers. We suggest that shifts in photosynthetically-driven tropical macroalgal changes due to OA will most likely occur in moderate to high-irradiance environments when CCMs are ineffective at meeting the C-demands of photosynthesis. Further, facultative use of HCO(3)(−) allows greater access to CO(2) for photosynthesis under OA conditions, particularly amongst fleshy macroalgae, which could contribute to enhance fleshy species dominance over calcifiers.
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spelling pubmed-60134602018-06-27 The role of irradiance and C-use strategies in tropical macroalgae photosynthetic response to ocean acidification Zweng, Regina C. Koch, Marguerite S. Bowes, George Sci Rep Article Fleshy macroalgae may increase photosynthesis with greater CO(2) availability under ocean acidification (OA) and outcompete calcifying macroalgae important for tropical reef accretion. Macroalgae use energy-dependent carbon concentrating mechanisms (CCMs) to take up HCO(3)(−), the dominant inorganic carbon for marine photosynthesis, but carbon-use strategies may depend on the pCO(2), pH and irradiance. We examined photosynthesis in eight tropical macroalgae across a range of irradiances (0–1200 μmol photon m(−2) s(−1)), pH levels (7.5–8.5) and CO(2) concentrations (3–43 μmol kg(−1)). Species-specific CCM strategies were assessed using inhibitors and δ(13)C isotope signatures. Our results indicate that the log of irradiance is a predictor of the photosynthetic response to elevated pCO(2) (R(2) > 0.95). All species utilized HCO(3)(−), exhibited diverse C-use pathways and demonstrated facultative HCO(3)(−) use. All fleshy species had positive photosynthetic responses to OA, in contrast to a split amongst calcifiers. We suggest that shifts in photosynthetically-driven tropical macroalgal changes due to OA will most likely occur in moderate to high-irradiance environments when CCMs are ineffective at meeting the C-demands of photosynthesis. Further, facultative use of HCO(3)(−) allows greater access to CO(2) for photosynthesis under OA conditions, particularly amongst fleshy macroalgae, which could contribute to enhance fleshy species dominance over calcifiers. Nature Publishing Group UK 2018-06-21 /pmc/articles/PMC6013460/ /pubmed/29930306 http://dx.doi.org/10.1038/s41598-018-27333-0 Text en © The Author(s) 2018 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.
spellingShingle Article
Zweng, Regina C.
Koch, Marguerite S.
Bowes, George
The role of irradiance and C-use strategies in tropical macroalgae photosynthetic response to ocean acidification
title The role of irradiance and C-use strategies in tropical macroalgae photosynthetic response to ocean acidification
title_full The role of irradiance and C-use strategies in tropical macroalgae photosynthetic response to ocean acidification
title_fullStr The role of irradiance and C-use strategies in tropical macroalgae photosynthetic response to ocean acidification
title_full_unstemmed The role of irradiance and C-use strategies in tropical macroalgae photosynthetic response to ocean acidification
title_short The role of irradiance and C-use strategies in tropical macroalgae photosynthetic response to ocean acidification
title_sort role of irradiance and c-use strategies in tropical macroalgae photosynthetic response to ocean acidification
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6013460/
https://www.ncbi.nlm.nih.gov/pubmed/29930306
http://dx.doi.org/10.1038/s41598-018-27333-0
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