KNAW Repository

Nitrogen fixation by Trichodesmium and small diazotrophs in the subtropical northeast Atlantic

Benavides, M. and Agawin, N.S.R. and Arístegui, J. and Ferrio, P. and Stal, L.J. (2011) Nitrogen fixation by Trichodesmium and small diazotrophs in the subtropical northeast Atlantic. Aquatic Microbial Ecology, 65, 43-53. ISSN 0948-3055.

[img]PDF - Published Version
Restricted to KNAW only until 01 November 2015.

942Kb

Official URL: http://dx.doi.org/10.3354/ame01534

Abstract

We measured gross and net nitrogen fixation in fractionated samples (organisms >10 µm and <10 µm), and the density of Trichodesmium, during a cruise along the northeast Atlantic boundary current system and during 2 mesoscale experiments in the upwelling systems of Cape Silleiro (northwest Iberia) and Cape Ghir (northwest Africa). The density of Trichodesmium (<0.5 trichomes l−1) and its associated rates of nitrogen fixation (<0.1 μmol N m−2 d−1) were low. Trichomes appeared to accumulate at frontal sites—such as upwelling filaments and the Azores Front. Gross and net rates of nitrogen fixation were always <0.4 nmol N l−1d−1 except off the northwest African coast where a gross nitrogen fixation peak of 0.98 nmol N l−1 d−1 was measured. The <10 µm fraction contributed more to both gross and net nitrogen fixation than did the >10 µm fraction in most of the areas studied. The <10 µm fraction was responsible for 70 to 92% of the total nitrogen fixation in cold nutrient-rich areas. The contribution of small diazotrophs to nitrogen fixation in the upwelling sites suggests that the distribution and activity of these organisms are more widespread than previously thought.

Item Type:Article
Institutes:Nederlands Instituut voor Ecologie (NIOO)
ID Code:9745
Deposited On:10 Oct 2011 02:00
Last Modified:14 Oct 2013 13:53

Repository Staff Only: item control page