Ecosystem function and particle flux dynamics across the Mackenzie Shelf (Beaufort Sea, Arctic Ocean): an integrative analysis of spatial variability and biophysical forcings

• Published in: Biogeosciences
• Main Authors: Forest, A., Babin, M., Stemmann, L., Picheral, M., Sampei, M., Fortier, L., Gratton, Y., Belanger, S., Devred, E., Sahlin, J., Doxaran, D., Joux, F., Ortega-Retuerta, E., Martin, J., Jeffrey, W. H., Gasser, B., Miquel, J. Carlos
• Other Authors: Université Laval Québec (ULaval), Laboratoire d'océanographie de Villefranche (LOV), Observatoire océanologique de Villefranche-sur-mer (OOVM), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Centre Eau Terre Environnement Québec (INRS - ETE), Institut National de la Recherche Scientifique Québec (INRS), Departement de Biologie, Chimie et Géographie, Université du Québec à Rimouski (UQAR), Groupe de recherche sur les environnements nordiques BORÉAS, Takuvik Joint International Laboratory ULAVAL-CNRS, Université Laval Québec (ULaval)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Océanographie Microbienne (LOMIC), Observatoire océanologique de Banyuls (OOB), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Centro Universitario de la Defensa de Zaragoza, Center for Environmental Diagnostics and Bioremediation Pensacola (UWF, University of West Florida Pensacola (UWF), Marine Environment Laboratories Monaco (IAEA-MEL), International Atomic Energy Agency Vienna (IAEA)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2013
• Subjects: [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography; Arctic; Arctic Ocean; Beaufort Sea; Mackenzie Shelf; Phytoplankton; Sea ice
• Online Access: https://hal.archives-ouvertes.fr/hal-03502645; https://hal.archives-ouvertes.fr/hal-03502645/document; https://hal.archives-ouvertes.fr/hal-03502645/file/bg-10-2833-2013.pdf; https://doi.org/10.5194/bg-10-2833-2013

International audience A better understanding of how environmental changes affect organic matter fluxes in Arctic marine ecosystems is sorely needed. Here we combine mooring times series, ship-based measurements and remote sensing to assess the variability and forcing factors of vertical fluxes of particulate organic carbon (POC) across the Mackenzie Shelf in 2009. We developed a geospatial model of these fluxes to proceed to an integrative analysis of their determinants in summer. Flux data were obtained with sediment traps moored around 125m and via a regional empirical algorithm applied to particle size distributions (17 classes from 0.08-4.2 mm) measured by an Underwater Vision Profiler 5. The low fractal dimension (i.e., porous, fluffy particles) derived from the algorithm (1.26 +/- 0.34) and the dominance (similar to 77 %) of rapidly sinking small aggregates (< 0.5 mm) in total fluxes suggested that settling material was the product of recent aggregation processes between marine detritus, gel-like substances, and ballast minerals. Modeled settling velocity of small and large aggregates was, respectively, higher and lower than in previous studies within which a high fractal dimension (i.e., more compact particles) was consequential of deep-trap collection (similar to 400-1300 m). Redundancy analyses and forward selection of abiotic/biotic parameters, linear trends, and spatial structures (i.e., principal coordinates of neighbor matrices, PCNM) were conducted to partition the variation of the 17 POC flux size classes. Flux variability was explained at 69.5% by the addition of a temporal trend, 7 significant PCNM, and 9 biophysical variables. The first PCNM canonical axis (44.5% of spatial variance) reflected the total magnitude of POC fluxes through a shelf-basin gradient controlled by bottom depth and sea ice concentration (p < 0.01). The second most important spatial structure (5.0 %) corresponded to areas where shelf break upwelling is known to occur under easterlies and where phytoplankton was ...