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Carbon-use strategies in macroalgea: differential responses to lowered pH and implications for ocean acidification
Citation
Cornwall, CE and Hepburn, CD and Pritchard, D and Currie, KI and McGraw, CM and Hunter, KA and Hurd, CL, Carbon-use strategies in macroalgea: differential responses to lowered pH and implications for ocean acidification, Journal of Phycology, 48, (1) pp. 137-144. ISSN 0022-3646 (2012) [Refereed Article]
Copyright Statement
Copyright 2011 Phycological Society of America
DOI: doi:10.1111/j.1529-8817.2011.01085.x
Abstract
Ocean acidification (OA) is a reduction in oceanic
pH due to increased absorption of anthropogenically
produced CO2. This change alters the seawater
concentrations of inorganic carbon species that are
utilized by macroalgae for photosynthesis and calcification:
CO2 and HCO3 increase; CO32 decreases.
Two common methods of experimentally reducing
seawater pH differentially alter other aspects of carbonate
chemistry: the addition of CO2 gas mimics
changes predicted due to OA, while the addition of
HCl results in a comparatively lower [HCO3]. We
measured the short-term photosynthetic responses
of five macroalgal species with various carbon-use
strategies in one of three seawater pH treatments:
pH 7.5 lowered by bubbling CO2 gas, pH 7.5 lowered
by HCl, and ambient pH 7.9. There was no difference
in photosynthetic rates between the CO2,
HCl, or pH 7.9 treatments for any of the species
examined. However, the ability of macroalgae to
raise the pH of the surrounding seawater through
carbon uptake was greatest in the pH 7.5 treatments.
Modeling of pH change due to carbon assimilation
indicated that macroalgal species that could
utilize HCO3 increased their use of CO2 in the pH
7.5 treatments compared to pH 7.9 treatments. Species
only capable of using CO2 did so exclusively in
all treatments. Although CO2 is not likely to be limiting
for photosynthesis for the macroalgal species
examined, the diffusive uptake of CO2 is less energetically
expensive than active HCO3- uptake, and
so HCO3--using macroalgae may benefit in future
seawater with elevated CO2.
Key index words: bicarbonate; carbon acquisition;
carbon dioxide; climate change; dissolved inorganic
carbon; HCl; macroalgae; ocean acidification;
pH drift; photosynthesis
Abbreviations: AT, total alkalinity; CCM, carbonconcentrating
mechanism; DIC, dissolved
inorganic carbon; OA, ocean acidification; PFD,
photon flux density; PQ, photosynthetic quotient;
PS, photosynthesis
Item Details
Item Type: | Refereed Article |
---|---|
Keywords: | ocean acidification, seaweed, carbon aquisition, pH |
Research Division: | Environmental Sciences |
Research Group: | Climate change impacts and adaptation |
Research Field: | Ecological impacts of climate change and ecological adaptation |
Objective Division: | Environmental Policy, Climate Change and Natural Hazards |
Objective Group: | Adaptation to climate change |
Objective Field: | Ecosystem adaptation to climate change |
UTAS Author: | Cornwall, CE (Dr Chris Cornwall) |
UTAS Author: | Hurd, CL (Professor Catriona Hurd) |
ID Code: | 91468 |
Year Published: | 2012 |
Web of Science® Times Cited: | 125 |
Deposited By: | IMAS Research and Education Centre |
Deposited On: | 2014-05-20 |
Last Modified: | 2014-11-24 |
Downloads: | 0 |
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