title: Altitudinal patterns of diversity and functional traits of metabolically active microorganisms in stream biofilms.
abstract: Resources structure ecological communities and potentially link biodiversity to energy flow. It is commonly believed that functional traits (generalists versus specialists) involved in the exploitation of resources depend on resource availability and environmental fluctuations. The longitudinal nature of stream ecosystems provides changing resources to stream biota with yet unknown effects on microbial functional traits and community structure. We investigated the impact of autochthonous (algal extract) and allochthonous (spruce extract) resources, as they change along alpine streams from above to below the treeline, on microbial diversity, community composition and functions of benthic biofilms. Combining bromodeoxyuridine labelling and 454 pyrosequencing, we showed that diversity was lower upstream than downstream of the treeline and that community composition changed along the altitudinal gradient. We also found that, especially for allochthonous resources, specialisation by biofilm bacteria increased along that same gradient. Our results suggest that in streams below the treeline biofilm diversity, specialisation and functioning are associated with increasing niche differentiation as potentially modulated by divers allochthonous and autochthonous constituents contributing to resources. These findings expand our current understanding on biofilm structure and function in alpine streams.
authors.affiliation: Department of Limnology and Oceanography, Faculty of Life Sciences, University of Vienna, Vienna, Austria.
authors.forename: Linda
authors.initials: L
authors.lastname: Wilhelm
authors.affiliation: School of Engineering, University of Glasgow, Glasgow, UK.
authors.forename: Katharina
authors.initials: K
authors.lastname: Besemer
authors.affiliation: Department of Ecogenomics and Systems Biology, University of Vienna, Vienna, Austria.
authors.forename: Lena
authors.initials: L
authors.lastname: Fragner
authors.affiliation: Lake and Glacier Ecology Research Group, Institute of Ecology, University of Innsbruck, Innsbruck, Austria.
authors.forename: Hannes
authors.initials: H
authors.lastname: Peter
authors.affiliation: Department of Ecogenomics and Systems Biology, University of Vienna, Vienna, Austria.
authors.forename: Wolfram
authors.initials: W
authors.lastname: Weckwerth
authors.affiliation: Department of Limnology and Oceanography, Faculty of Life Sciences, University of Vienna, Vienna, Austria.|Stream Biofilm and Ecosystem Research Laboratory, School of Architecture, Civil and Environmental Engineering, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
authors.forename: Tom J
authors.initials: TJ
authors.lastname: Battin
mesh_terms: D000531:Altitude; D001317:Austria; D001419:Bacteria / Q000145:classification*; D044822:Biodiversity; D018441:Biofilms; D001973:Bromodeoxyuridine / Q000737:chemistry; D002244:Carbon / Q000737:chemistry; D004247:DNA / Q000032:analysis; D017753:Ecosystem; D016133:Polymerase Chain Reaction; D045483:Rivers / Q000382:microbiology*; D017422:Sequence Analysis, DNA; D014197:Trees; D014867:Water / Q000737:chemistry; D014871:Water Microbiology
chemical_list: D014867:Water; D002244:Carbon; D004247:DNA; D001973:Bromodeoxyuridine