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| Titel |
Phytoplankton-bacteria coupling under elevated CO2 levels: a stable isotope labelling study |
| VerfasserIn |
A. Kluijver, K. Soetaert, K. G. Schulz, U. Riebesell, R. G. J. Bellerby, J. J. Middelburg |
| 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 ; 7, no. 11 ; Nr. 7, no. 11 (2010-11-24), S.3783-3797 |
| Datensatznummer |
250005070
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| Publikation (Nr.) |
 copernicus.org/bg-7-3783-2010.pdf |
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| Zusammenfassung |
| The potential impact of rising carbon dioxide (CO2) on carbon transfer
from phytoplankton to bacteria was investigated during the 2005 PeECE III
mesocosm study in Bergen, Norway. Sets of mesocosms, in which a
phytoplankton bloom was induced by nutrient addition, were incubated under
1× (~350 μatm), 2× (~700 μatm), and 3× present day
CO2 (~1050 μatm) initial seawater and sustained atmospheric
CO2 levels for 3 weeks. 13C labelled bicarbonate was added to all
mesocosms to follow the transfer of carbon from dissolved inorganic carbon
(DIC) into phytoplankton and subsequently heterotrophic bacteria, and
settling particles. Isotope ratios of polar-lipid-derived fatty acids (PLFA)
were used to infer the biomass and production of phytoplankton and bacteria.
Phytoplankton PLFA were enriched within one day after label addition, whilst
it took another 3 days before bacteria showed substantial enrichment.
Group-specific primary production measurements revealed that
coccolithophores showed higher primary production than green algae and
diatoms. Elevated CO2 had a significant positive effect on post-bloom
biomass of green algae, diatoms, and bacteria. A simple model based on
measured isotope ratios of phytoplankton and bacteria revealed that CO2
had no significant effect on the carbon transfer efficiency from
phytoplankton to bacteria during the bloom. There was no indication of
CO2 effects on enhanced settling based on isotope mixing models during
the phytoplankton bloom, but this could not be determined in the post-bloom
phase. Our results suggest that CO2 effects are most pronounced in the
post-bloom phase, under nutrient limitation. |
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