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| Titel |
Large-scale environmental controls on microbial biofilms in high-alpine streams |
| VerfasserIn |
T. J. Battin, A. Wille, R. Psenner, A. Richter |
| 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 ; 1, no. 2 ; Nr. 1, no. 2 (2004-12-27), S.159-171 |
| Datensatznummer |
250000140
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| Publikation (Nr.) |
 copernicus.org/bg-1-159-2004.pdf |
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| Zusammenfassung |
| Glaciers are highly responsive to global warming and important agents of
landscape heterogeneity. While it is well established that glacial ablation
and snowmelt regulate stream discharge, linkage among streams and
streamwater geochemistry, the controls of these factors on stream microbial
biofilms remain insufficiently understood. We investigated glacial
(metakryal, hypokryal), groundwater-fed (krenal) and snow-fed (rhithral)
streams - all of them representative for alpine stream networks - and
present evidence that these hydrologic and hydrogeochemical factors
differentially affect sediment microbial biofilms. Average microbial biomass
and bacterial carbon production were low in the glacial streams, whereas
bacterial cell size, biomass, and carbon production were higher in the
tributaries, most notably in the krenal stream. Whole-cell in situ
fluorescence hybridization revealed reduced detection rates of the
Eubacteria and higher abundance of α-Proteobacteria in the glacial stream, a pattern that
most probably reflects the trophic status of this ecosystem. Our data
suggest low flow during the onset of snowmelt and autumn as a short period
(hot moment) of favorable environmental conditions with pulsed inputs of
allochthonous nitrate and dissolved organic carbon, and with
disproportionately high microbial growth. Tributaries are relatively more
constant and favorable environments than kryal streams, and serve as
possible sources of microbes and organic matter to the main glacial channel
during periods (e.g., snowmelt) of elevated hydrologic linkage among
streams. Ice and snow dynamics - and their impact on the amount and
composition of dissolved organic matter - have a crucial impact on stream
biofilms, and we thus need to consider microbes and critical hydrological
episodes in future models of alpine stream communities. |
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