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| Titel |
Coupling of heterotrophic bacteria to phytoplankton bloom development at different pCO2 levels: a mesocosm study |
| VerfasserIn |
M. Allgaier, U. Riebesell, M. Vogt, R. Thyrhaug, H.-P. Grossart |
| 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. 4 ; Nr. 5, no. 4 (2008-07-21), S.1007-1022 |
| Datensatznummer |
250002674
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| Publikation (Nr.) |
 copernicus.org/bg-5-1007-2008.pdf |
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| Zusammenfassung |
| The predicted rise in anthropogenic CO2
emissions will increase CO2 concentrations and decrease seawater pH in
the upper ocean. Recent studies have revealed effects of pCO2 induced
changes in seawater chemistry on a variety of marine life forms, in
particular calcifying organisms. To test whether the predicted increase in
pCO2 will directly or indirectly (via changes in phytoplankton
dynamics) affect abundance, activities, and community composition of
heterotrophic bacteria during phytoplankton bloom development, we have
aerated mesocosms with CO2 to obtain triplicates with three different
partial pressures of CO2 (pCO2): 350 μatm (1×CO2), 700 μatm (2×CO2) and 1050 μatm
(3×CO2). The development of a phytoplankton bloom was initiated by the
addition of nitrate and phosphate. In accordance to an elevated carbon to
nitrogen drawdown at increasing pCO2, bacterial production (BPP) of
free-living and attached bacteria as well as cell-specific BPP (csBPP) of
attached bacteria were related to the C:N ratio of suspended matter. These
relationships significantly differed among treatments. However, bacterial
abundance and activities were not statistically different among treatments.
Solely community structure of free-living bacteria changed with pCO2
whereas that of attached bacteria seemed to be independent of pCO2 but tightly coupled to phytoplankton bloom development. Our findings
imply that changes in pCO2, although reflected by changes in community
structure of free-living bacteria, do not directly affect bacterial
activity. Furthermore, bacterial activity and dynamics of heterotrophic
bacteria, especially of attached bacteria, were tightly correlated to
phytoplankton development and, hence, may also potentially depend on changes
in pCO2. |
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