%0 Unpublished work
%T Nutrients limitation of primary productivity in the Southeast Pacific (BIOSOPE cruise)
%+ University of Southern California (USC)
%+ Laboratoire d'océanographie de Villefranche (LOV)
%+ Dalhousie University [Halifax]
%+ Institute of Microbiology ASCR
%+ Laboratoire d'océanographie et de biogéochimie (LOB)
%+ Rutgers, The State University of New Jersey [New Brunswick] (RU)
%+ University of California [Santa Cruz] (UC Santa Cruz)
%+ Station biologique de Roscoff [Roscoff] (SBR)
%A Bonnet, Sophie
%A Guieu, Cecile
%A Bruyant, F.
%A Prášil, O.
%A van Wambeke, France
%A Raimbault, Patrick
%A Grob, C.
%A Moutin, T.
%A Gorbunov, M. Y.
%A Zehr, J. P.
%A Masquelier, S. M.
%A Garczarek, Laurence
%A Claustre, Hervé
%Z Revue sans Comité de lecture
%< avec comité de lecture
%@ 1810-6277
%J Biogeosciences Discussions
%I European Geosciences Union
%V 4
%N 4
%P 2733-2759
%8 2007-08-09
%D 2007
%Z Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO]
%Z Sciences of the Universe [physics]/Astrophysics [astro-ph]
%Z Sciences of the Universe [physics]/Continental interfaces, environment
%Z Sciences of the Universe [physics]/Ocean, Atmosphere
%Z Sciences of the Universe [physics]/Earth SciencesOther publications
%X Iron is an essential nutrient involved in a variety of biological processes in the ocean, including photosynthesis, respiration and nitrogen fixation. Atmospheric deposition of aerosols is recognized as the main source of iron for the surface ocean. In high nutrient, low chlorophyll areas, it is now clearly established that iron limits phytoplankton productivity but its biogeochemical role in low nutrient, low chlorophyll environments has been poorly studied. We investigated this question in the unexplored southeast Pacific, arguably the most oligotrophic area of the global ocean. Situated far from any continental aerosol source, the atmospheric iron flux to this province is amongst the lowest of the world ocean. Here we report that, despite low dissolved iron concentrations (~0.1 nmol l<sup>-1</sup>) measured across the whole gyre (3 stations situated in the center, the western and the eastern edge), photosynthesis and primary productivity are only limited by iron availability at the border of the gyre, but not in the center. The seasonal stability of the gyre has apparently allowed for the development of populations acclimated to these extreme oligotrophic conditions. Moreover, despite clear evidence of nitrogen limitation in the central gyre, we were unable to measure nitrogen fixation in our experiments, even after iron and/or phosphate additions, and cyanobacterial <i>nifH</i> gene abundances were extremely low compared to the North Pacific Gyre. The South Pacific gyre is therefore unique with respect to the physiological status of its phytoplankton populations.
%G English
%2 https://hal.science/hal-00330258/document
%2 https://hal.science/hal-00330258/file/bgd-4-2733-2007.pdf
%L hal-00330258
%U https://hal.science/hal-00330258
%~ INSU
%~ UPMC
%~ CNRS
%~ UNIV-AMU
%~ EGU
%~ EGU-BGD
%~ GIP-BE
%~ LOV
%~ UPMC_POLE_3
%~ CMM
%~ SORBONNE-UNIVERSITE
%~ SU-SCIENCES
%~ SU-SCI
%~ UMS-829
%~ SU-TI
%~ LOV_OMTAB
%~ ALLIANCE-SU
%~ SBR