Predicting Effects of Ocean Acidification and Warming on Algae Lacking Carbon Concentrating Mechanisms

Seaweeds that lack carbon-concentrating mechanisms are potentially inorganic carbon-limited under current air equilibrium conditions. To estimate effects of increased atmospheric carbon dioxide concentration and ocean acidification on photosynthetic rates, we modeled rates of photosynthesis in respo...

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Main Authors:	Kübler, Janet E., Dudgeon, Steven R.
Format:	Online
Language:	English
Published:	Public Library of Science 2015
Online Access:	https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4501704/

id	pubmed-4501704
recordtype	oai_dc
spelling	pubmed-45017042015-07-17 Predicting Effects of Ocean Acidification and Warming on Algae Lacking Carbon Concentrating Mechanisms Kübler, Janet E. Dudgeon, Steven R. Research Article Seaweeds that lack carbon-concentrating mechanisms are potentially inorganic carbon-limited under current air equilibrium conditions. To estimate effects of increased atmospheric carbon dioxide concentration and ocean acidification on photosynthetic rates, we modeled rates of photosynthesis in response to pCO2, temperature, and their interaction under limiting and saturating photon flux densities. We synthesized the available data for photosynthetic responses of red seaweeds lacking carbon-concentrating mechanisms to light and temperature. The model was parameterized with published data and known carbonate system dynamics. The model predicts that direction and magnitude of response to pCO2 and temperature, depend on photon flux density. At sub-saturating light intensities, photosynthetic rates are predicted to be low and respond positively to increasing pCO2, and negatively to increasing temperature. Consequently, pCO2 and temperature are predicted to interact antagonistically to influence photosynthetic rates at low PFD. The model predicts that pCO2 will have a much larger effect than temperature at sub-saturating light intensities. However, photosynthetic rates under low light will not increase proportionately as pCO2 in seawater continues to rise. In the range of light saturation (Ik), both CO2 and temperature have positive effects on photosynthetic rate and correspondingly strong predicted synergistic effects. At saturating light intensities, the response of photosynthetic rates to increasing pCO2 approaches linearity, but the model also predicts increased importance of thermal over pCO2 effects, with effects acting additively. Increasing boundary layer thickness decreased the effect of added pCO2 and, for very thick boundary layers, overwhelmed the effect of temperature on photosynthetic rates. The maximum photosynthetic rates of strictly CO2-using algae are low, so even large percentage increases in rates with climate change will not contribute much to changing primary production in the habitats where they commonly live. Public Library of Science 2015-07-14 /pmc/articles/PMC4501704/ /pubmed/26172263 http://dx.doi.org/10.1371/journal.pone.0132806 Text en © 2015 Kübler, Dudgeon http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are properly credited.
repository_type	Open Access Journal
institution_category	Foreign Institution
institution	US National Center for Biotechnology Information
building	NCBI PubMed
collection	Online Access
language	English
format	Online
author	Kübler, Janet E. Dudgeon, Steven R.
spellingShingle	Kübler, Janet E. Dudgeon, Steven R. Predicting Effects of Ocean Acidification and Warming on Algae Lacking Carbon Concentrating Mechanisms
author_facet	Kübler, Janet E. Dudgeon, Steven R.
author_sort	Kübler, Janet E.
title	Predicting Effects of Ocean Acidification and Warming on Algae Lacking Carbon Concentrating Mechanisms
title_short	Predicting Effects of Ocean Acidification and Warming on Algae Lacking Carbon Concentrating Mechanisms
title_full	Predicting Effects of Ocean Acidification and Warming on Algae Lacking Carbon Concentrating Mechanisms
title_fullStr	Predicting Effects of Ocean Acidification and Warming on Algae Lacking Carbon Concentrating Mechanisms
title_full_unstemmed	Predicting Effects of Ocean Acidification and Warming on Algae Lacking Carbon Concentrating Mechanisms
title_sort	predicting effects of ocean acidification and warming on algae lacking carbon concentrating mechanisms
description	Seaweeds that lack carbon-concentrating mechanisms are potentially inorganic carbon-limited under current air equilibrium conditions. To estimate effects of increased atmospheric carbon dioxide concentration and ocean acidification on photosynthetic rates, we modeled rates of photosynthesis in response to pCO2, temperature, and their interaction under limiting and saturating photon flux densities. We synthesized the available data for photosynthetic responses of red seaweeds lacking carbon-concentrating mechanisms to light and temperature. The model was parameterized with published data and known carbonate system dynamics. The model predicts that direction and magnitude of response to pCO2 and temperature, depend on photon flux density. At sub-saturating light intensities, photosynthetic rates are predicted to be low and respond positively to increasing pCO2, and negatively to increasing temperature. Consequently, pCO2 and temperature are predicted to interact antagonistically to influence photosynthetic rates at low PFD. The model predicts that pCO2 will have a much larger effect than temperature at sub-saturating light intensities. However, photosynthetic rates under low light will not increase proportionately as pCO2 in seawater continues to rise. In the range of light saturation (Ik), both CO2 and temperature have positive effects on photosynthetic rate and correspondingly strong predicted synergistic effects. At saturating light intensities, the response of photosynthetic rates to increasing pCO2 approaches linearity, but the model also predicts increased importance of thermal over pCO2 effects, with effects acting additively. Increasing boundary layer thickness decreased the effect of added pCO2 and, for very thick boundary layers, overwhelmed the effect of temperature on photosynthetic rates. The maximum photosynthetic rates of strictly CO2-using algae are low, so even large percentage increases in rates with climate change will not contribute much to changing primary production in the habitats where they commonly live.
publisher	Public Library of Science
publishDate	2015
url	https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4501704/
_version_	1613247694308900864

Predicting Effects of Ocean Acidification and Warming on Algae Lacking Carbon Concentrating Mechanisms

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