Missing nitrogen fixation in the Benguela region

Wasmund, Norbert; Struck, Ulrich; Hansen, Anja; Flohr, Anita ORCID: https://orcid.org/0000-0002-5018-5379; Nausch, Günther; Grüttmüller, Annett; Voss, Maren. 2015 Missing nitrogen fixation in the Benguela region. Deep Sea Research Part I: Oceanographic Research Papers, 106. 30-41. 10.1016/j.dsr.2015.10.007

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Official URL: http://dx.doi.org/10.1016/j.dsr.2015.10.007

Abstract/Summary

Opposing opinions on the importance of nitrogen fixation in the northern Benguela upwelling region provoked us to investigate the magnitude of nitrogen fixation in front of northern Namibia and southern Angola. Measurements of nitrogen fixation rates using the 15N method at 66 stations during seven cruises from 2008 to 2014 showed that, in general, the 15N content in the biomass did not increase after tracer incubation with 15N2, indicating that no nitrogen fixation occurred. Correspondingly, the filamentous nitrogen-fixing cyanobacterium Trichodesmium was almost not present. The abundant picocyanobacteria did obviously not perform nitrogen fixation to a significant degree. The artificial improvement of conditions for nitrogen fixation in mesocosm experiments, including phosphate and iron additions and a warmer temperature, failed to induce nitrogen fixation. A plausible explanation of these findings is a lack of conditioned cells for nitrogen fixation in the Benguela region.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	10.1016/j.dsr.2015.10.007
ISSN:	09670637
Date made live:	11 Mar 2020 13:23 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/527116

Item Type:

Publication - Article

Digital Object Identifier (DOI):

10.1016/j.dsr.2015.10.007

ISSN:

09670637

Date made live:

11 Mar 2020 13:23 +0 (UTC)

URI:

https://nora.nerc.ac.uk/id/eprint/527116