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| Titel |
Enhanced bacterial decomposition with increasing addition of autochthonous to allochthonous carbon without any effect on bacterial community composition |
| VerfasserIn |
K. Attermeyer, T. Hornick, Z. E. Kayler, A. Bahr, E. Zwirnmann, H.-P. Grossart, K. Premke |
| 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 ; 11, no. 6 ; Nr. 11, no. 6 (2014-03-20), S.1479-1489 |
| Datensatznummer |
250117301
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| Publikation (Nr.) |
 copernicus.org/bg-11-1479-2014.pdf |
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| Zusammenfassung |
| Dissolved organic carbon (DOC) concentrations – mainly of terrestrial origin
– are increasing worldwide in inland waters. Heterotrophic bacteria are the
main consumers of DOC and thus determine DOC temporal dynamics and
availability for higher trophic levels. Our aim was to study bacterial
carbon (C) turnover with respect to DOC quantity and chemical quality using
both allochthonous and autochthonous DOC sources. We incubated a natural
bacterial community with allochthonous C (13C-labeled beech leachate)
and increased concentrations and pulses (intermittent occurrence of organic
matter input) of autochthonous C (phytoplankton lysate). We then determined
bacterial C consumption, activities, and community composition together with
the C flow through bacteria using stable C isotopes. The chemical analysis
of single sources revealed differences in aromaticity and low- and high-molecular-weight substance fractions (LMWS and HMWS, respectively) between
allochthonous and autochthonous C sources. Both DOC sources (allochthonous
and autochthonous DOC) were metabolized at a high bacterial growth
efficiency (BGE) around 50%. In treatments with mixed sources, rising
concentrations of added autochthonous DOC resulted in a further, significant
increase in bacterial DOC consumption of up to 68% when nutrients were
not limiting. This rise was accompanied by a decrease in the humic substance
(HS) fraction and an increase in bacterial biomass. Changes in DOC
concentration and consumption in mixed treatments did not affect bacterial
community composition (BCC), but BCC differed in single vs. mixed
incubations. Our study highlights that DOC quantity affects bacterial C
consumption but not BCC in nutrient-rich aquatic systems. BCC shifted when a
mixture of allochthonous and autochthonous C was provided simultaneously to
the bacterial community. Our results indicate that chemical quality rather
than source of DOC per se (allochthonous vs. autochthonous) determines bacterial
DOC turnover. |
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