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.
Wasmund N., Struck U., Hansen A., Flohr A., Nausch G., Grüttmüller A. and Voss M. (2015) Missing nitrogen fixation in the Benguela region. 106: 30-41. 10.1016/j.dsr.2015.10.007
@article{Wasmund2015,
Title = {Missing nitrogen fixation in the Benguela region},
Author = {Wasmund, Norbert and Struck, Ulrich and Hansen, Anja and Flohr, Anita and Nausch, Günther and Grüttmüller, Annett and Voss, Maren},
Editor = {},
Year = {2015},
Pages = {30-41},
Volume = {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.},
}
TY - JOUR
AU - Wasmund, Norbert
AU - Struck, Ulrich
AU - Hansen, Anja
AU - Flohr, Anita
AU - Nausch, Günther
AU - Grüttmüller, Annett
AU - Voss, Maren
TI - Missing nitrogen fixation in the Benguela region
PY - 2015
SP - 30-41
VL - 106
DO - 10.1016/j.dsr.2015.10.007
AB - 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.
ER -
