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Marine Ecology Progress Series

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MEPS 535:99-115 (2015)  -  DOI:

Benthic oxygen exchange in a live coralline algal bed and an adjacent sandy habitat: an eddy covariance study

Karl M. Attard1,2,*, Henrik Stahl3,4, Nicholas A. Kamenos5, Gavin Turner3, Heidi L. Burdett5,6,7, Ronnie N. Glud1,2,3,8

1Nordic Centre for Earth Evolution (NordCEE), University of Southern Denmark, 5230 Odense M, Denmark
2Greenland Climate Research Centre, Greenland Institute of Natural Resources, 3900 Nuuk, Greenland
3Scottish Association for Marine Science, Scottish Marine Institute, Oban PA37 1QA, UK
4Natural Science and Public Health Department, Zayed University, PO Box 19282, Dubai, United Arab Emirates
5School of Geographical and Earth Sciences, University of Glasgow, Glasgow G12 8QQ, UK
6Department of Earth and Environmental Sciences, University of St. Andrews, St. Andrews KY16 9AL, UK
7Scottish Oceans Institute, University of St Andrews, St. Andrews KY16 8LB, UK
8Arctic Research Centre, University of Århus, 8000 Århus C, Denmark
*Corresponding author:

ABSTRACT: Coralline algal (maerl) beds are widespread, slow-growing, structurally complex perennial habitats that support high biodiversity, yet are significantly understudied compared to seagrass beds or kelp forests. We present the first eddy covariance (EC) study on a live maerl bed, assessing the community benthic gross primary productivity (GPP), respiration (R), and net ecosystem metabolism (NEM) derived from diel EC time series collected during 5 seasonal measurement campaigns in temperate Loch Sween, Scotland. Measurements were also carried out at an adjacent (~20 m distant) permeable sandy habitat. The O2 exchange rate was highly dynamic, driven by light availability and the ambient tidally-driven flow velocity. Linear relationships between the EC O2 fluxes and available light indicate that the benthic phototrophic communities were lightlimited. Compensation irradiance (Ec) varied seasonally and was typically ~1.8-fold lower at the maerl bed compared to the sand. Substantial GPP was evident at both sites; however, the maerl bed and the sand habitat were net heterotrophic during each sampling campaign. Additional inputs of ~4 and ~7 mol m-2 yr-1 of carbon at the maerl bed and sand site, respectively, were required to sustain the benthic O2 demand. Thus, the 2 benthic habitats efficiently entrap organic carbon and are sinks of organic material in the coastal zone. Parallel deployment of 0.1 m2 benthic chambers during nighttime revealed O2 uptake rates that varied by up to ~8-fold between replicate chambers (from -0.4 to -3.0 mmol O2 m-2 h-1; n = 4). However, despite extensive O2 flux variability on meter horizontal scales, mean rates of O2 uptake as resolved in parallel by chambers and EC were typically within 20% of one another.

KEY WORDS: Benthic oxygen exchange · Benthic primary production · Coastal carbon cycling · Coralline algae · Permeable sediment · Eddy covariance · Benthic chambers

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Cite this article as: Attard KM, Stahl H, Kamenos NA, Turner G, Burdett HL, Glud RN (2015) Benthic oxygen exchange in a live coralline algal bed and an adjacent sandy habitat: an eddy covariance study. Mar Ecol Prog Ser 535:99-115.

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