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| Titel |
Competition for inorganic and organic forms of nitrogen and phosphorous between phytoplankton and bacteria during an Emiliania huxleyi spring bloom |
| VerfasserIn |
T. Løvdal, C. Eichner, H.-P. Grossart, V. Carbonnel, L. Chou, V. Martin-Jézéquel, T. F. Thingstad |
| 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 ; 5, no. 2 ; Nr. 5, no. 2 (2008-03-12), S.371-383 |
| Datensatznummer |
250002372
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| Publikation (Nr.) |
 copernicus.org/bg-5-371-2008.pdf |
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| Zusammenfassung |
| Using 15N and 33P, we measured the turnover of organic and
inorganic nitrogen (N) and phosphorus (P) substrates, and the partitioning
of N and P from these sources into two size fractions of marine osmotrophs
during the course of a phytoplankton bloom in a nutrient manipulated
mesocosm. The larger size fraction (>0.8 μm), mainly consisting of
the coccolithophorid Emiliania huxleyi, but also including an increasing amount of large
particle-associated bacteria as the bloom proceeded, dominated uptake of the
inorganic forms NH4+, NO3−, and
PO43−. The uptake of N from leucine, and P from
ATP and dissolved DNA, was initially dominated by the 0.8–0.2 μm size
fraction, but shifted towards dominance by the >0.8 μm size fraction
as the system turned to an increasing degree of N-deficiency. Normalizing
uptake to biomass of phytoplankton and heterotrophic bacteria revealed that
organisms in the 0.8–0.2 μm size fraction had higher specific affinity
for leucine-N than those in the >0.8 μm size fraction when N was
deficient, whereas the opposite was the case for NH4+.
There was no such difference regarding the specific affinity for P
substrates. Since heterotrophic bacteria seem to acquire N from organic
compounds like leucine more efficiently than phytoplankton, our results
suggest different structuring of the microbial food chain in N-limited
relative to P-limited environments. |
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