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| Titel |
Growth and specific P-uptake rates of bacterial and phytoplanktonic communities in the Southeast Pacific (BIOSOPE cruise) |
| VerfasserIn |
S. Duhamel, T. Moutin, F. Wambeke, B. Mooy, P. Rimmelin, P. Raimbault, H. Claustre |
| 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 ; 4, no. 6 ; Nr. 4, no. 6 (2007-11-08), S.941-956 |
| Datensatznummer |
250001991
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| Publikation (Nr.) |
 copernicus.org/bg-4-941-2007.pdf |
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| Zusammenfassung |
| Predicting heterotrophic bacteria and phytoplankton specific growth rates
(μ ) is of great scientific interest. Many methods have been developed
in order to assess bacterial or phytoplankton μ. One widely used method
is to estimate μ from data obtained on biomass or cell abundance and
rates of biomass or cell production. According to Kirchman (2002), the most
appropriate approach for estimating μ is simply to divide the
production rate by the biomass or cell abundance estimate. Most methods
using this approach to estimate μ are based on carbon (C) incorporation
rates and C biomass measurements. Nevertheless it is also possible to
estimate μ using phosphate (P) data. We showed that particulate
phosphate (PartP) can be used to estimate biomass and that the P uptake rate
to PartP ratio can be employed to assess μ. Contrary to other methods
using C, this estimator does not need conversion factors and provides an
evaluation of μ for both autotrophic and heterotrophic organisms. We
report values of P-based μ in three size fractions (0.2–0.6; 0.6–2 and
>2 μm) along a Southeast Pacific transect, over a wide range of
P-replete trophic status. P-based μ values were higher in the 0.6–2 μm
fraction than in the >2 μm fraction, suggesting that
picoplankton-sized cells grew faster than the larger cells, whatever the
trophic regime encountered. Picoplankton-sized cells grew significantly
faster in the deep chlorophyll maximum layer than in the upper part of the
photic zone in the oligotrophic gyre area, suggesting that picoplankton
might outcompete >2 μm cells in this particular high-nutrient,
low-light environment. P-based μ attributed to free-living bacteria
(0.2-0.6 μm) and picoplankton (0.6–2 μm) size-fractions were
relatively low (0.11±0.07 d−1 and 0.14±0.04 d−1,
respectively) in the Southeast Pacific gyre, suggesting that the microbial
community turns over very slowly. |
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