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Hörtnagl, P. H., University of Innsbruck, Innsbruck, Austria, paul.hoertnagl@uibk.ac.at
Pérez, M. T., University of Innsbruck, Innsbruck, Austria, maria.perez@uibk.ac.at
Sommaruga, R. ., University of Innsbruck, Innsbruck, Austria, ruben.sommaruga@uibk.ac.at

DIFFERENCES IN BACTERIAL ACTIVITY AND COMPOSITION OF SURFACE MICROLAYER AND UNDERLYING WATER IN MOUNTAIN LAKES

We assessed the differences in water physico-chemical characteristics, in bacterial community composition (BCC) and single-cell activity between the surface microlayer (SML) and the underlying water (ULW) of six mountain lakes located across an altitude gradient. SML-samples consisted on the first 900 µm of the lake surface, whereas the ULW was sampled at 0.2 m depth. Single-cell activity and BCC were determined by a combination of microautoradiography and catalyzed reporter deposition fluorescence in situ hybridisation (MAR- and CARD-FISH). Both, the SML and the ULW were dominated by Betaproteobacteria followed by Actinobacteria (except in one lake). The abundance of the latter group was found to be significantly higher in the underlying water of all lakes, whereas Betaproteobacteria had the highest single-cell activity in both layers. DOC concentrations were significantly higher in the SML of all lakes. Our results indicate that the air-water interface of mountain lakes represents a particularly active water layer mostly dominated by Betaproteobacteria.

Poster presentation

Session #:018
Date: 01-28-09
Time: 18:00 - 20:00

Presentation is given by student: Yes