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| Titel |
Nitrogen fixation and the diazotroph community in the temperate coastal region of the northwestern North Pacific |
| VerfasserIn |
T. Shiozaki, T. Nagata, M. Ijichi, K. Furuya |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 12, no. 15 ; Nr. 12, no. 15 (2015-08-07), S.4751-4764 |
| Datensatznummer |
250118057
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| Publikation (Nr.) |
 copernicus.org/bg-12-4751-2015.pdf |
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| Zusammenfassung |
| Nitrogen fixation in temperate oceans is a potentially important, but poorly
understood process that may influence the marine nitrogen budget. This study
determined seasonal variations in nitrogen fixation and the diazotroph
community within the euphotic zone in the temperate coastal region of the
northwestern North Pacific. Nitrogen fixation as high as 13.6 nmol N L−1 d−1
was measured from early summer to fall when the surface
temperature exceeded 14.2 °C (but was lower than 24.3 °C)
and the surface nitrate concentration was low (≤ 0.30 μM),
although we also detected nitrogen fixation in subsurface layers (42–62 m)
where nitrate concentrations were high (> 1 μM). Clone
library analysis results indicated that nifH gene sequences were omnipresent
throughout the investigation period. During the period when nitrogen
fixation was detected (early summer to fall), the genes affiliated with
UCYN-A, Trichodesmium, and γ-proteobacterial phylotype γ-24774A11 were
frequently recovered. In contrast, when nitrogen fixation was undetectable
(winter to spring), many sequences affiliated with Cluster III diazotrophs
(putative anaerobic bacteria) were recovered. Quantitative PCR analysis
revealed that UCYN-A was relatively abundant from early to late summer
compared with Trichodesmium and γ-24774A11, whereas Trichodesmium abundance was the highest
among the three groups during fall. |
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