Missing nitrogen fixation in the Benguela region
Missing nitrogen fixation in the Benguela region
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.
Nitrogen fixation, Trichodesmium, Picocyanobacteria, Mesocosm, Nutrients, Temperature, Benguela upwelling
30-41
Wasmund, Norbert
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Struck, Ulrich
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Hansen, Anja
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Flohr, Anita
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Nausch, Günther
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Grüttmüller, Annett
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Voss, Maren
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December 2015
Wasmund, Norbert
2fa63b2c-dabf-4af9-88f8-67833afecc5d
Struck, Ulrich
9a1dcd81-7dfe-405c-8baf-2c88bfb6bc09
Hansen, Anja
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Flohr, Anita
1e293a22-bdba-408e-9608-fed8b65e4e79
Nausch, Günther
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Grüttmüller, Annett
f7edba47-c855-4b1b-b20b-2cbe29770ea9
Voss, Maren
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Wasmund, Norbert, Struck, Ulrich, Hansen, Anja, Flohr, Anita, Nausch, Günther, Grüttmüller, Annett and Voss, Maren
(2015)
Missing nitrogen fixation in the Benguela region.
Deep Sea Research Part I: Oceanographic Research Papers, 106, .
(doi:10.1016/j.dsr.2015.10.007).
Abstract
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.
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Published date: December 2015
Keywords:
Nitrogen fixation, Trichodesmium, Picocyanobacteria, Mesocosm, Nutrients, Temperature, Benguela upwelling
Organisations:
Geochemistry
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Local EPrints ID: 400923
URI: http://eprints.soton.ac.uk/id/eprint/400923
ISSN: 0967-0637
PURE UUID: f0068a1b-5d63-45d3-99cf-cf9b8e6cf13b
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Date deposited: 30 Sep 2016 13:15
Last modified: 15 Mar 2024 02:32
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Author:
Norbert Wasmund
Author:
Ulrich Struck
Author:
Anja Hansen
Author:
Anita Flohr
Author:
Günther Nausch
Author:
Annett Grüttmüller
Author:
Maren Voss
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