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| Titel |
Nutrient limitation of primary productivity in the Southeast Pacific (BIOSOPE cruise) |
| VerfasserIn |
S. Bonnet, C. Guieu, F. Bruyant, O. Prášil, F. Wambeke, P. Raimbault, T. Moutin, C. Grob, M. Y. Gorbunov, J. P. Zehr, S. M. Masquelier, L. Garczarek, H. Claustre |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 5, no. 1 ; Nr. 5, no. 1 (2008-02-20), S.215-225 |
| Datensatznummer |
250002238
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| Publikation (Nr.) |
 copernicus.org/bg-5-215-2008.pdf |
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| Zusammenfassung |
| Iron is an essential nutrient involved in a variety of biological processes
in the ocean, including photosynthesis, respiration and dinitrogen 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−1) across
the whole gyre (3 stations located in the center and at the western and the
eastern edges), 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 dinitrogen fixation in our experiments, even after iron and/or
phosphate additions, and cyanobacterial nif H 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. |
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