Contributors: Environnements et Paléoenvironnements OCéaniques (EPOC); Observatoire aquitain des sciences de l'univers (OASU); Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École Pratique des Hautes Études (EPHE); Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Centre National de la Recherche Scientifique (CNRS); Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR); Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM); Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS); Détection, évaluation, gestion des risques CHROniques et éMErgents (CHROME) / Université de Nîmes (CHROME); Université de Nîmes (UNIMES); Royal Netherlands Institute for Sea Research (NIOZ); The EDDYCO project (INSU EC2CO/DRIL program) provided financial support for this study. The Région Aquitaine (FEBBA project) and the IZOFLUX project from the French National Research Agency (white program) funded the EC system. The Région Aquitaine (FEBBA project) and the Vrije Universiteit Brussel supported the two-year postdoctoral fellowships awarded to P.P. The development of the new EC system, EC2, was realized in collaboration with Unisense A/S and the NIOZ-Yerseke. We would like to express our thanks to the INSU team from L’Albert Lucas and Henry Bouillard and Christian Portier from EPOC. This work has been carried out within the framework of the Cluster of Excellence COTE; ANR-10-BLAN-0612,IZOFLUX,Étude intégrée de l'Impact des herbiers de ZOstères sur les processus et FLUX benthiques en milieu côtier(2010); ANR-10-LABX-0045,COTE,COntinental To coastal Ecosystems: evolution, adaptability and governance(2010)
نبذة مختصرة : International audience ; To the best of our knowledge, the understanding of benthic metabolism of coastal sedimentary areas is still limited due to the complexity of determining their true in situ dynamics over large spatial and temporal scales. Multidisciplinary methodological approaches are then necessary to increase our comprehension of factors controlling benthic processes and fluxes. An aquatic Eddy Covariance (EC) system and Benthic Chambers (BC) were simultaneously deployed during the winter of 2013 in the Bay of Brest within a Maerl bed and a bare mudflat to quantify and compare exchange at the sediment–water interface. Environmental abiotic parameters (i.e., light, temperature, salinity, current velocity and water depth) were additionally monitored to better understand the mechanisms driving benthic exchange. At both sites, EC measurements showed short-term variations (i.e. 15 min) in benthic fluxes according to environmental conditions. At the Maerl station, EC fluxes ranged from -21.0 mmol m−2 d−1 to 71.3 mmol m−2 d−1 and averaged 22.0 ± 32.7 mmol m−2 d−1 (mean SD), whilst at the bare muddy station, EC fluxes ranged from -43.1 mmol m−2 d−1 to 12.1 mmol m−2 d−1 and averaged -15.9 ± 14.0 mmol m−2 d−1 (mean SD) during the total deployment. Eddy Covariance and Benthic Chambers measurements showed similar patterns of temporal flux changes at both sites. However, at the Maerl station, BC may have underestimated community respiration. This may be due to the relative large size of the EC footprint (compared to BC), which takes into account the mesoscale spatial heterogeneity (e.g. may have included contributions from bare sediment patches). Also, we hypothesize that the influence of bioturbation induced by large-sized mobile benthic fauna on sediment oxygen consumption was not fully captured by BC compared to EC. Overall, the results of the present study highlight the importance of taking into account specific methodology limitations with respect to sediment spatial macro-heterogeneity and short-term ...
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