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Marine Ecology Progress Series

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MEPS 543:55-71 (2016)  -  DOI:

Benthic oxygen exchange over a heterogeneous Zostera noltei meadow in a temperate coastal ecosystem

Marie Lise Delgard1,3,*, Bruno Deflandre1, Guillaume Bernard1, Marion Richard1, Emeric Kochoni1, Céline Charbonnier1, Florian Cesbron2, Edouard Metzger2, Antoine Grémare1, Pierre Anschutz

1Université de Bordeaux, EPOC, UMR 5805, F33615 Pessac, France
2Université d’Angers, LPG-BIAF, UMR CNRS 6112, 49045 Angers Cedex, France
3Present address: Department of Environmental Sciences, University of Virginia, Charlottesville, Virginia 22904-4123, USA
*Corresponding author:

ABSTRACT: Seagrass meadows support intense but highly variable benthic metabolic rates that still need to be better evaluated to determine an accurate trophic status. The present study assessed how seagrasses and associated benthic macrofauna control spatiotemporal changes in benthic oxygen exchanges within a temperate bay. Based on seasonal sampling over a complete year cycle, the diffusive oxygen uptake (DOU), community respiration (CR) and gross primary production (GPP) were measured in a Zostera noltei meadow within Arcachon Bay, taking into account its spatial heterogeneity. Oxygen fluxes were assessed in sediment cores, within which benthic macrofauna and seagrass abundances and biomasses were quantified. The presence of Z. noltei did not significantly affect the DOU. Seasonal changes in CR and GPP correlated strongly with temperature in the presence of Z. noltei. The characteristics of benthic macrofauna associated with Z. noltei only weakly affected seasonal changes in CR. High spatial changes in both GPP and CR were mainly driven by the aboveground biomass of Z. noltei. When extrapolated to the whole intertidal area of the bay, in spite of limitations, our results suggest (1) overall higher contributions to CR and GPP from the seagrass meadow than from bare sediments, even though alternative primary producers in bare sediments (likely microphytobenthos) contributed significantly during winter; (2) an annual decrease in CR and GPP of 35 and 41%, respectively, resulting from the decline in Z. noltei of 25% between 2005 and 2007; and (3) a strong seasonality in the magnitude of this decrease, which was high during autumn and low during winter. 

KEY WORDS: Benthic oxygen exchange · Seagrass · Zostera noltei · Benthic macrofauna · Arcachon Bay · Community respiration · Gross primary production

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Cite this article as: Delgard ML, Deflandre B, Bernard G, Richard M and others (2016) Benthic oxygen exchange over a heterogeneous Zostera noltei meadow in a temperate coastal ecosystem. Mar Ecol Prog Ser 543:55-71.

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