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Canopy macroalgae influence understorey corallines’ metabolic control of near-surface pH and oxygen concentration


Cornwall, CE and Pilditch, CA and Hepburn, CD and Hurd, CL, Canopy macroalgae influence understorey corallines' metabolic control of near-surface pH and oxygen concentration, Marine Ecology - Progress Series, 525 pp. 81-95. ISSN 0171-8630 (2015) [Refereed Article]

Copyright Statement

Copyright 2015 Inter-Research

DOI: doi:10.3354/meps11190


Understorey macroalgae can alter pH at their surface via metabolic activity within the concentration boundary layer (CBL), but it is unknown to what degree the presence of larger macroalgal canopies can modify the pH micro-environment of understorey species. We examined whether flow reduction by a canopy-forming macroalga could alter the thickness of the CBL at the surface of understorey crustose coralline macroalgae (CCA). This could lead to a greater metabolic influence of macroalgae on the pH and oxygen environment at the coralline’s surface. Three experimental treatments were examined in a re-circulating flume: (1) a full canopy (consisting of Carpophyllum maschalocarpum) and understorey (Corallina officinalis and CCA), (2) a mimic (plastic/silk) canopy plus understorey, and (3) an understorey only. Profiles of seawater velocity and pH/O2 concentration gradients were measured at 3 bulk seawater velocities (2, 4 and 8 cm s-1) above the CCA in both the light and dark. Canopy macroalgae altered the pH and O2 environment encountered by understorey coralline algae via their physical presence rather than by directly altering bulk seawater chemistry through their metabolism. Reduced seawater velocities beneath Carpophyllum and mimic canopies resulted in increased CBL thicknesses, higher pH (up to 8.9) and O2 concentrations in the light, and lower pH (down to 7.74) and O2 concentrations in the dark. The ability of canopies to facilitate greater metabolic changes in pH at the surface of understorey species highlights a previously unrecorded species interaction that could play an important role in influencing the physiology and ecology of understorey assemblages.

Item Details

Item Type:Refereed Article
Keywords:ocean acidification, water motion, seaweed, hydrodynamics, coralline algae
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:Hurd, CL (Professor Catriona Hurd)
ID Code:104210
Year Published:2015
Web of Science® Times Cited:28
Deposited By:IMAS Research and Education Centre
Deposited On:2015-11-04
Last Modified:2017-10-31

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