Nutrient limitation of primary productivity in the Southeast Pacific (BIOSOPE cruise)

By S. Bonnet, C. Guieu, F. Bruyant, O. Prášil, F. Wambeke, P. Raimbault, T. Moutin, C. Grob, M. Gorbunov, Jonathan P. Zehr and 3 more. 2007

155 citations recorded by the source corpus.

Abstract. 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.

Subfields: Ecology, Oceanography

View Paper: https://www.semanticscholar.org/paper/967dad96bb0fad729df75787425fb18838deb260

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Citations in the corpus

Biogeographical controls on the marine nitrogen fixers (2011, background): “In particular, the modeled lack of diazotrophs in the southeast Pacific Ocean compares well to the observations from two cruises [Mague et al., 1974; Bonnet et al., 2008, 2009] that did not find any evidence of nitrogen fixers in this region (except for a small pocket at 26°S).”
Phosphate availability and the ultimate control of new nitrogen input by nitrogen fixation in the tropical Pacific Ocean (2007, background): “Bonnet et al. (2007) found the presence of extremely low numbers of Group A cyanobacterial phylotypes (see their Table 2).”
Distribution of diverse nitrogen fixers in the global ocean (2010, background): “Trichodesmium has been observed to grow in most warm oligotrophic subtropical and tropical regions of the ocean [Carpenter and Romans, 1991; Capone et al., 1997], apart from the western equatorial and Southeastern subtropical Pacific Ocean [Mague et al., 1974; Bonnet et al., 2008, 2009].”
Environmental control of open‐ocean phytoplankton groups: Now and in the future (2010, background): “In the Southern Ocean, the main environmental controls on P. antarctica are reported to be irradiance and Fe (Table 1; Arrigo et al. 2003; Arrigo and Tagliabue 2005; Arrigo 2007).”