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Ocean Acidification Accelerates the Growth of Two Bloom-Forming Macroalgae

While there is growing interest in understanding how marine life will respond to future ocean acidification, many coastal ecosystems currently experience intense acidification in response to upwelling, eutrophication, or riverine discharge. Such acidification can be inhibitory to calcifying animals,...

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Autores principales: Young, Craig S., Gobler, Christopher J.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2016
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4866684/
https://www.ncbi.nlm.nih.gov/pubmed/27176637
http://dx.doi.org/10.1371/journal.pone.0155152
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author Young, Craig S.
Gobler, Christopher J.
author_facet Young, Craig S.
Gobler, Christopher J.
author_sort Young, Craig S.
collection PubMed
description While there is growing interest in understanding how marine life will respond to future ocean acidification, many coastal ecosystems currently experience intense acidification in response to upwelling, eutrophication, or riverine discharge. Such acidification can be inhibitory to calcifying animals, but less is known regarding how non-calcifying macroalgae may respond to elevated CO(2). Here, we report on experiments performed during summer through fall with North Atlantic populations of Gracilaria and Ulva that were grown in situ within a mesotrophic estuary (Shinnecock Bay, NY, USA) or exposed to normal and elevated, but environmentally realistic, levels of pCO(2) and/or nutrients (nitrogen and phosphorus). In nearly all experiments, the growth rates of Gracilaria were significantly increased by an average of 70% beyond in situ and control conditions when exposed to elevated levels of pCO(2) (p<0.05), but were unaffected by nutrient enrichment. In contrast, the growth response of Ulva was more complex as this alga experienced significantly (p<0.05) increased growth rates in response to both elevated pCO(2) and elevated nutrients and, in two cases, pCO(2) and nutrients interacted to provide a synergistically enhanced growth rate for Ulva. Across all experiments, elevated pCO(2) significantly increased Ulva growth rates by 30% (p<0.05), while the response to nutrients was smaller (p>0.05). The δ(13)C content of both Gracilaria and Ulva decreased two-to-three fold when grown under elevated pCO(2) (p<0.001) and mixing models demonstrated these macroalgae experienced a physiological shift from near exclusive use of HCO(3)(-) to primarily CO(2) use when exposed to elevated pCO(2). This shift in carbon use coupled with significantly increased growth in response to elevated pCO(2) suggests that photosynthesis of these algae was limited by their inorganic carbon supply. Given that eutrophication can yield elevated levels of pCO(2), this study suggests that the overgrowth of macroalgae in eutrophic estuaries can be directly promoted by acidification, a process that will intensify in the coming decades.
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spelling pubmed-48666842016-05-18 Ocean Acidification Accelerates the Growth of Two Bloom-Forming Macroalgae Young, Craig S. Gobler, Christopher J. PLoS One Research Article While there is growing interest in understanding how marine life will respond to future ocean acidification, many coastal ecosystems currently experience intense acidification in response to upwelling, eutrophication, or riverine discharge. Such acidification can be inhibitory to calcifying animals, but less is known regarding how non-calcifying macroalgae may respond to elevated CO(2). Here, we report on experiments performed during summer through fall with North Atlantic populations of Gracilaria and Ulva that were grown in situ within a mesotrophic estuary (Shinnecock Bay, NY, USA) or exposed to normal and elevated, but environmentally realistic, levels of pCO(2) and/or nutrients (nitrogen and phosphorus). In nearly all experiments, the growth rates of Gracilaria were significantly increased by an average of 70% beyond in situ and control conditions when exposed to elevated levels of pCO(2) (p<0.05), but were unaffected by nutrient enrichment. In contrast, the growth response of Ulva was more complex as this alga experienced significantly (p<0.05) increased growth rates in response to both elevated pCO(2) and elevated nutrients and, in two cases, pCO(2) and nutrients interacted to provide a synergistically enhanced growth rate for Ulva. Across all experiments, elevated pCO(2) significantly increased Ulva growth rates by 30% (p<0.05), while the response to nutrients was smaller (p>0.05). The δ(13)C content of both Gracilaria and Ulva decreased two-to-three fold when grown under elevated pCO(2) (p<0.001) and mixing models demonstrated these macroalgae experienced a physiological shift from near exclusive use of HCO(3)(-) to primarily CO(2) use when exposed to elevated pCO(2). This shift in carbon use coupled with significantly increased growth in response to elevated pCO(2) suggests that photosynthesis of these algae was limited by their inorganic carbon supply. Given that eutrophication can yield elevated levels of pCO(2), this study suggests that the overgrowth of macroalgae in eutrophic estuaries can be directly promoted by acidification, a process that will intensify in the coming decades. Public Library of Science 2016-05-13 /pmc/articles/PMC4866684/ /pubmed/27176637 http://dx.doi.org/10.1371/journal.pone.0155152 Text en © 2016 Young, Gobler http://creativecommons.org/licenses/by/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
spellingShingle Research Article
Young, Craig S.
Gobler, Christopher J.
Ocean Acidification Accelerates the Growth of Two Bloom-Forming Macroalgae
title Ocean Acidification Accelerates the Growth of Two Bloom-Forming Macroalgae
title_full Ocean Acidification Accelerates the Growth of Two Bloom-Forming Macroalgae
title_fullStr Ocean Acidification Accelerates the Growth of Two Bloom-Forming Macroalgae
title_full_unstemmed Ocean Acidification Accelerates the Growth of Two Bloom-Forming Macroalgae
title_short Ocean Acidification Accelerates the Growth of Two Bloom-Forming Macroalgae
title_sort ocean acidification accelerates the growth of two bloom-forming macroalgae
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4866684/
https://www.ncbi.nlm.nih.gov/pubmed/27176637
http://dx.doi.org/10.1371/journal.pone.0155152
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