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| Titel |
Temporal variations in microbial activities and carbon turnover in subtidal sandy sediments |
| VerfasserIn |
S. I. Böer, C. Arnosti, J. E. E. Beusekom, A. Boetius  |
| 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 ; 6, no. 7 ; Nr. 6, no. 7 (2009-07-10), S.1149-1165 |
| Datensatznummer |
250003906
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| Publikation (Nr.) |
 copernicus.org/bg-6-1149-2009.pdf |
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| Zusammenfassung |
| Temporal dynamics and vertical patterns in bacterial abundances and
activities were studied in a shallow subtidal sand flat in the
Sylt-Rømø Basin (North Frisian Wadden Sea, Germany). Extracellular
enzymatic activities, bacterial carbon production and community respiration
showed strong (factor of 4–5) temporal variations that were mostly related
to seasonal temperature change and to changes in substrate
availability. These temporal patterns in enzymatic activity were barely reflected in
bacterial (200–400 mmol C m−2) and microphytobenthic biomass
(800–1500 mmol C m−2) or the sedimentary carbohydrate inventory (1300–2900 mmol C m−2),
suggesting that grazing controls the standing stocks of the
microphytobenthic and bacterial assemblages. Despite their exposure to
strong hydrodynamic forces such as tidal currents and wind-induced wave
surge, the subtidal sandy sediments showed persistent vertical gradients in
bacterial abundances, carbon production and extracellular
enzymatic activities at all times. The vertical distribution of these
parameters was tightly coupled to that of the microphytobenthos, dominated
by diatoms. Despite the low organic carbon content typical for surge-exposed
sandy sediments, high extracellular enzymatic activities and bacterial
carbon production rates indicate a very active heterotrophic bacterial
community, with a gross secondary productivity of 30–180 mmol C m−2,
and a biomass turnover time of 2–18 days. Our data suggest that this high
activity is supported by the rapid flux of carbohydrates from
microphytobenthic primary productivity. Accordingly, the potential
activities of enzymes hydrolyzing carbohydrates cover most of the total
bacterial carbon demand during all seasons. |
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