biogeography of nitrogen fixers

We explore the diversity of marine nitrogen fixers, or diazotrophs, as well as the factors that control their habitat in a global ocean model. Analogs of Trichodesmium, unicellular cyanobacteria and diatom-diazotroph associations occupy habitats consistent with those observed in the ocean, confined to tropical and subtropical waters. In the model’s South Pacific, diazotroph abundance is extremely sensitive to the delivery of iron and parameterization of its biogeochemical cycle.

Figure caption: Surface distribution of the three major types of diazotrophs generated in the model (µmol P l–1, log scale, first 50 m depth average). Small generated diazotrophs are associated with the unicellular diazotrophs, big and diatom with the DDA (diatom-diazotroph association)  and the other big with the Trichodesmium.

For more information

  • Monteiro, F. and M. Follows, 2009: On the interannual variability of nitrogen fixation in the subtropical gyres. Journal of Marine Research, accepted with minor revisions.
  • Monteiro, F., M. J. Follows and S. Dutkiewicz. (2009). Diversity and habitat of nitrogen fixers in a model ocean. In preparation.
  • ASLO Aquatic Sciences Meeting, Nice, France, January 25-30, 2009. “Diversity of diazotrophs and their habitat in a globale ocean model.” F. Monteiro, M.J. Follows, and S. Dutkiewicz.  Poster presentation. See poster (PDF).