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Concentration boundary layers and complex assemblages of macroalgae: Implications for the effects of ocean acidification on understory coralline algae
Citation
Cornwall, CE and Hepburn, CD and Pilditch, CA and Hurd, CL, Concentration boundary layers and complex assemblages of macroalgae: Implications for the effects of ocean acidification on understory coralline algae, Limnology and Oceanography, 58, (1) pp. 121-130. ISSN 0024-3590 (2013) [Refereed Article]
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Copyright Statement
Copyirght 2013 The Association for the Sciences of Limnology and Oceanography, Inc.
DOI: doi:10.4319/lo.2013.58.1.0121
Abstract
Metabolic processes have the potential to modulate the effects of ocean acidification (OA) in nearshore
macroalgal beds. We investigated whether natural mixed assemblages of the articulate coralline macroalga
Arthrocardia corymbosa and understory crustose coralline algae (CCA) altered pH and O2 concentrations within
and immediately above their canopies. In a unidirectional flume, we tested the effect of water velocity (0–
0.1 m s-1), bulk seawater pH (ambient pH 8.05, and pH 7.65), and irradiance (photosynthetically saturating light
and darkness) on pH and O2 concentration gradients, and the derived concentration boundary layer (CBL)
thickness. At bulk seawater pH 7.65 and slow velocities (0 and 0.015 m s-1), pH at the CCA surface increased to
7.90–8.00 in the light. Although these manipulations were short term, this indicates a potential daytime buffering
capacity that could alleviate the effects of OA. Photosynthetic activity also increased O2 concentrations at the
surface of the CCA. However, this moderating capacity was flow dependent; the CBL thickness decreased from
an average of 26.8 mm from the CCA surface at 0.015 m s-1 to 4.1 mm at 0.04 m s-1. The reverse trends occurred
in the dark, with respiration causing pH and O2 concentrations to decrease at the CCA surface. At all flow
velocities the CBL thicknesses (up to 68 mm) were much greater than those previously published, indicating that
the presence of canopies can alter the CBL substantially. In situ, the height of macroalgal canopies can be an
order of magnitude larger than those used here, indicating that the degree of buffering to OA will be context
dependent.
Item Details
Item Type: | Refereed Article |
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Keywords: | ocean acidification, seaweed, boundary layers, hydrodynamics |
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: | 91461 |
Year Published: | 2013 |
Web of Science® Times Cited: | 61 |
Deposited By: | IMAS Research and Education Centre |
Deposited On: | 2014-05-20 |
Last Modified: | 2014-11-24 |
Downloads: | 0 |
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