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Marine Ecology Progress Series

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MEPS 417:1-12 (2010)  -  DOI:

Benthic O2 exchange across hard-bottom substrates quantified by eddy correlation in a sub-Arctic fjord

Ronnie N. Glud1,2,3,*, Peter Berg4, Andrew Hume1,4, Paul Batty2, Martin E. Blicher2, Kunuk Lennert2, Søren Rysgaard2

1Scottish Association for Marine Science, Dunstaffnage Marine Laboratory, PA37 1QA, Dunbeg, UK
2Greenland Climate Research Centre (c/o Greenland Institute of Natural Resources), Kivioq 2, PO Box 570, 3900 Nuuk, Greenland
3Southern Danish University, Institute of Biology and Nordic Center for Earth Evolution (NordCee), 5230 Odense M, Denmark
4Department of Environmental Science, University of Virginia, 291 McCormick Road, Charlottesville, Virginia 22904, USA

ABSTRACT: Oxygen exchange across the seabed is a key measure for quantifying benthic carbon turnover. However, technical limitations have restricted such measurements to sedimentary areas. Few assessments on hard-bottom substrates exist although such biotopes are frequent along many coastlines. In spring 2009, we used the non-invasive eddy correlation technique to quantify the in situ O2 exchange rate across 3 typical substrates in West Greenland: (1) in soft sediments, the O2 exchange in darkness averaged 2.0 mmol m–2 h–1. The rate exceeded the O2 exchange quantified from microprofile measurements by 80%, but was not significantly different from parallel core incubations. (2) Measurements across consolidated sand and stones revealed a high activity with average O2 exchange similar to that of sedimentary areas. Despite being net heterotrophic, the benthic primary production on average amounted to 27 mmol O2 m–2 d–1, which per unit area is similar to the pelagic gross production of the central fjord. Carbon fixed by benthic diatoms and coralline red algae was efficiently recycled by microbes or grazed by the abundant epifauna. (3) A vertical cliff covered with sea cucumbers also revealed high O2 consumption rates (1.2 mmol m–2 h–1). The O2 exchange derived from the eddy correlation approach exhibited pronounced short-term variability reflecting the interplay of several dynamic controls, most importantly short-term variations in local hydrodynamics. All together, measurements across hard-bottom substrates revealed active benthic communities that mediate high carbon turnover rates.

KEY WORDS: Benthic photosynthesis · Microsensors · Remineralization · In situ technology · Psolus fabricii · Strongylocentrotus droebachiensis

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Cite this article as: Glud RN, Berg P, Hume A, Batty P, Blicher ME, Lennert K, Rysgaard S (2010) Benthic O2 exchange across hard-bottom substrates quantified by eddy correlation in a sub-Arctic fjord. Mar Ecol Prog Ser 417:1-12.

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