FN Archimer Export Format
PT J
TI Evidence of high N2 fixation rates in the temperate northeast Atlantic
BT 
AF Fonseca-Batista, Debany
   Li, Xuefeng
   Riou, Virginie
   Michotey, Valérie
   Deman, Forian
   Fripiat, François
   Guasco, Sophie
   Brion, Natacha
   Lemaitre, Nolwenn
   Tonnard, Manon
   Gallinari, Morgane
   Planquette, Hélène
   Planchon, Frédéric
   Sarthou, Géraldine
   Elskens, Marc
   LaRoche, Julie
   Chou, Lei
   Dehairs, Frank
AS 1:1,2;2:1,3;3:4;4:4;5:1;6:5;7:4;8:1;9:1,6,7;10:6,8;11:6;12:6;13:6;14:6;15:1;16:2;17:3;18:1;
FF 1:;2:;3:;4:;5:;6:;7:;8:;9:;10:;11:;12:;13:;14:;15:;16:;17:;18:;
C1 Analytical, Environmental and Geo -Chemistry, Earth System Sciences Research Group, Vrije Universiteit Brussel, 1050 Brussels, Belgium
   Department of Biology, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada
   Service de Biogéochimie et Modélisation du Système Terre – Océanographie Chimique et Géochimie des Eaux, Université Libre de Bruxelles, 1050 Brussels, Belgium
   Aix-Marseille Université, Mediterranean Institute of Oceanography (MIO), UM 110 CNRS/INSU, IRD, 13288 Marseille, France
   Max Planck Institute for Chemistry, Climate Geochemistry Department, 55128 Mainz, Germany
   Laboratoire des sciences de l’Environnement MARin – CNRS UMR 6539 – Institut Universitaire Européen de la Mer, 29280 Plouzané, France
   Department of Earth Sciences, Institute of Geochemistry and Petrology, ETH-Zürich, 8092 Zürich, Switzerland
   Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, TAS 7001, Australia
C2 UNIV VRIJE BRUSSEL, BELGIUM
   UNIV DALHOUSIE, CANADA
   UNIV LIBRE BRUXELLES, BELGIUM
   UNIV AIX MARSEILLE, FRANCE
   MAX PLANCK INSTITUTE FOR CHEMISTRY, GERMANY
   UBO, FRANCE
   ETH ZURICH, SWITZERLAND
   UNIV TASMANIA, AUSTRALIA
UM LEMAR
IN WOS Cotutelle UMR
   copubli-france
   copubli-europe
   copubli-univ-france
   copubli-int-hors-europe
TC 16
UR https://archimer.ifremer.fr/doc/00461/57266/59317.pdf
   https://archimer.ifremer.fr/doc/00461/57266/59318.pdf
   https://archimer.ifremer.fr/doc/00461/57266/62725.pdf
   https://archimer.ifremer.fr/doc/00461/57266/62726.pdf
LA English
DT Article
CR GEOVIDE
BO Pourquoi pas ?
AB Diazotrophic activity and primary production (PP) were investigated along two transects (Belgica BG2014/14 and GEOVIDE cruises) off the western Iberian Margin and the Bay of Biscay (38.8–46.5°N; 8.0–19.7°W) in May 2014 close to the end of the spring bloom. We report substantial N2 fixation activities, reaching up to 65nmolNL−1d−1 and 1533µmolNm−2d−1 close to the Iberian Margin between 38.8°N and 40.7°N. Similar figures in the basin have only been reported in the temperate and tropical western North Atlantic waters with coastal, shelf or mesohaline characteristics, as opposed to the mostly open ocean conditions studied here. In agreement with previous studies, the qualitative assessment of nifH gene diversity (encoding the nitrogenase enzyme that fixes N2) suggested a predominance of heterotrophic diazotrophs, and the absence of filamentous cyanobacteria. At the sites where N2 fixation activity was highest sequences affiliated to UCYN-A1, obligate symbiont of eukaryotic prymnesiophyte algae, were recovered. The remaining phylotypes were non-cyanobacterial diazotrophs, known to live in association with suspended particles and zooplankton (i.e., Bacteroidetes, Firmicutes and Proteobacteria). Outside the area of exceptional activity, N2 fixation in the open ocean and at shelf-influenced sites was also relatively high, ranging from 81 to 384µmolNm−2d−1, but was undetectable in the central Bay of Biscay. We propose that the unexpectedly high heterotrophic N2 fixation activity recorded at the time of our study was sustained by the availability of phytoplankton derived organic matter (dissolved and/or particulate) resulting from the ongoing to post spring bloom. We pose that this organic material not only sustained bacterial production, but also provided sufficient nutrients essential for the nitrogenase activity (e.g., phosphorus). Dissolved Fe was supplied through atmospheric dust deposition during the month preceding our study and through advection of surface waters from the subtropical region and the shelf area. Our findings stress the need for a more detailed monitoring of the spatial and temporal distribution of oceanic N2 fixation in productive waters of the temperate North Atlantic to better constrain the basin-scale nitrogen input to the ocean inventory. 
PY 2019
SO Biogeosciences
SN 1726-4189
PU Copernicus GmbH
VL 16
IS 5
UT 000461174100003
BP 999
EP 1017
DI 10.5194/bg-16-999-2019
ID 57266
ER

EF