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| Titel |
Effects of increased atmospheric CO2 on small and intermediate sized osmotrophs during a nutrient induced phytoplankton bloom |
| VerfasserIn |
A. I. Paulino, J. K. Egge, A. Larsen |
| 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. 3 ; Nr. 5, no. 3 (2008-05-07), S.739-748 |
| Datensatznummer |
250002519
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| Publikation (Nr.) |
 copernicus.org/bg-5-739-2008.pdf |
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| Zusammenfassung |
| We report the transient population dynamic response of the osmotrophic
community initiated by a nutrient pulse in mesocosms exposed to different
pCO2 levels. Differences in phytoplankton and heterotrophic bacteria
abundances associated with the CO2 treatment are also described.
Coastal seawater was enclosed in floating mesocosms (27 m3) and
nutrients were supplied initially in order to stimulate growth of microbial
organisms, including the coccolitophorid Emiliania huxleyi. The mesocosms were modified to
achieve 350 μatm (1×CO2), 700 μatm (2×CO2) and 1050 μatm (3×CO2)
CO2 pressure. The temporal dynamics was related to
nutrient conditions in the enclosures. Numerically small osmotrophs
(picoeukaryotes and Synechoccocus sp.) dominated initially and towards the end of the
experiment, whereas intermediate sized osmotrophs bloomed as the initial
bloom of small sized osmotrophs ceased. Maximum concentrations of E. huxleyi were
approximately 4.6×103 cells ml−1 whereas other intermediate
sized osmotrophs reached approximately twice as high concentrations. The
osmotrophic succession pattern did not change, and neither were we able to
detect differences with regard to presence or absence of specific
osmotrophic taxa as a consequence of altered pCO2. Towards the end of
the experiment we did, however, record significantly higher picoeukaryotic-
and lower Synechococcus-abundances in the higher CO2 treatments. Slightly increased
cell concentrations of E. huxleyi and other nanoeukaryotes were also recorded at
elevated pCO2 on certain days. |
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