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Biogeosciences An interactive open-access journal of the European Geosciences Union
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Volume 5, issue 1
Biogeosciences, 5, 157–169, 2008
https://doi.org/10.5194/bg-5-157-2008
© Author(s) 2008. This work is distributed under
the Creative Commons Attribution 3.0 License.

Special issue: Biogeochemistry and Optics South Pacific Experiment...

Biogeosciences, 5, 157–169, 2008
https://doi.org/10.5194/bg-5-157-2008
© Author(s) 2008. This work is distributed under
the Creative Commons Attribution 3.0 License.

  08 Feb 2008

08 Feb 2008

Heterotrophic bacterial production in the eastern South Pacific: longitudinal trends and coupling with primary production

F. Van Wambeke1, I. Obernosterer2,3, T. Moutin4, S. Duhamel4,1, O. Ulloa5, and H. Claustre6 F. Van Wambeke et al.
  • 1Laboratoire de Microbiologie, Géochimie et Ecologie Marines (LMGEM), CNRS, UMR 6117, Université de la Méditerranée, Campus de Luminy – Case 901, 13288 Marseille cedex 9, France
  • 2Université Pierre et Marie Curie-Paris6, Laboratoire ARAGO, Avenue Fontaulé, BP44, 66650 Banyuls-sur-Mer, France
  • 3CNRS, UMR7621, Laboratoire d'Océanographie Biologique de Banyuls, Avenue Fontaulé, BP44, 66650 Banyuls-sur-Mer, France
  • 4Laboratoire d'Océanographie et de Biogéochimie (LOB), CNRS, UMR 6535, Université de la Méditerranée, Campus de Luminy – Case 901, 13288 Marseille cedex 9, France
  • 5Departmento de Oceanografía & Centro de Investigación Oceanográfica en el Pacífico Sur-Oriental, Universidad de Concepción, Casilla 160-C, Concepción, Chile
  • 6CNRS, Laboratoire d'océanographie de Villefranche, 06230 Villefranche-sur-Mer, France; Université Pierre et Marie Curie-Paris6, Laboratoire d'océanographie de Villefranche, 06230 Villefranche-sur-Mer, France

Abstract. Spatial variation of heterotrophic bacterial production and phytoplankton primary production were investigated across the eastern South Pacific Ocean (−141° W, −8° S to −72° W, −35° S) in November–December 2004. Bacterial production (3H leucine incorporation) integrated over the euphotic zone encompassed a wide range of values, from 43 mg C m−2 d−1 in the hyper-oligotrophic South Pacific Gyre to 392 mg C m−2 d−1 in the upwelling off Chile. In the gyre (120° W, 22° S) records of low phytoplankton biomass (7 mg Total Chla m−2) were obtained and fluxes of in situ 14C-based particulate primary production were as low as 153 mg C m−2 d−1, thus equal to the value considered as a limit for primary production under strong oligotrophic conditions. Average rates of 3H leucine incorporation rates, and leucine incorporation rates per cell (5–21 pmol l−1 h−1 and 15–56×10−21 mol cell−1 h−1, respectively) determined in the South Pacific gyre, were in the same range as those reported for other oligotrophic subtropical and temperate waters. Fluxes of dark community respiration, determined at selected stations across the transect varied in a narrow range (42–97 mmol O2 m−2 d−1), except for one station in the upwelling off Chile (245 mmol O2 m−2 d−1). Bacterial growth efficiencies varied between 5 and 38%. Bacterial carbon demand largely exceeded 14C particulate primary production across the South Pacific Ocean, but was lower or equal to gross community production.

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