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| Titel |
Vertical partitioning of phosphate uptake among picoplankton groups in the low Pi Mediterranean Sea |
| VerfasserIn |
A. Talarmin, F. Van Wambeke, P. Lebaron, T. Moutin |
| 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. 4 ; Nr. 12, no. 4 (2015-02-26), S.1237-1247 |
| Datensatznummer |
250117833
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| Publikation (Nr.) |
 copernicus.org/bg-12-1237-2015.pdf |
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| Zusammenfassung |
| Microbial transformations are key processes in marine phosphorus cycling. In
this study, we investigated the contribution of phototrophic and
heterotrophic groups to phosphate (Pi) uptake fluxes in the euphotic zone of the
low-Pi Mediterranean Sea and estimated Pi uptake kinetic
characteristics. Surface soluble reactive phosphorus (SRP) concentrations were in the range of 6–80 nmol L−1
across the transect, and the community Pi turnover times, assessed using
radiolabeled orthophosphate incubations, were longer in the western basin,
where the highest bulk and cellular rates were measured. Using live cell
sorting, four vertical profiles of Pi uptake rates were established for
heterotrophic prokaryotes (Hprok), phototrophic picoeukaryotes (Pic) and
Prochlorococcus (Proc) and Synechococcus (Syn) cyanobacteria. Hprok cells contributed up to 82% of
total Pi uptake fluxes in the superficial euphotic zone, through constantly
high abundances (2.7–10.2 × 105 cells mL−1) but
variable cellular rates (6.6 ± 9.3 amol P cell−1 h−1).
Cyanobacteria achieved most of the Pi uptake (up to 62%) around the deep
chlorophyll maximum depth, through high abundances (up to 1.4 × 105 Proc cells mL−1) and high cellular uptake rates (up to 40 and
402 amol P cell−1 h−1, respectively for Proc and Syn cells). At
saturating concentrations, maximum cellular rates up to 132 amol P cell−1 h−1 were measured for Syn at station (St.) C, which was 5 and 60
times higher than Proc and Hprok, respectively. Pi uptake capabilities of
the different groups likely contribute to their vertical distribution in the
low Pi Mediterranean Sea, possibly along with other energy limitations. |
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