title: Spatio-temporal patterns of major bacterial groups in alpine waters.
abstract: Glacial alpine landscapes are undergoing rapid transformation due to changes in climate. The loss of glacial ice mass has directly influenced hydrologic characteristics of alpine floodplains. Consequently, hyporheic sediment conditions are likely to change in the future as surface waters fed by glacial water (kryal) become groundwater dominated (krenal). Such environmental shifts may subsequently change bacterial community structure and thus potential ecosystem functioning. We quantitatively investigated the structure of major bacterial groups in glacial and groundwater-fed streams in three alpine floodplains during different hydrologic periods. Our results show the importance of several physico-chemical variables that reflect local geological characteristics as well as water source in structuring bacterial groups. For instance, Alpha-, Betaproteobacteria and Cytophaga-Flavobacteria were influenced by pH, conductivity and temperature as well as by inorganic and organic carbon compounds, whereas phosphorous compounds and nitrate showed specific influence on single bacterial groups. These results can be used to predict future bacterial group shifts, and potential ecosystem functioning, in alpine landscapes under environmental transformation.
authors.affiliation: Institute of Molecular Health Sciences, Professorship of Genetics, ETH Zurich, Zurich, Switzerland; Department of Aquatic Ecology, Swiss Federal Institute of Aquatic Science and Technology, Eawag, Dübendorf, Switzerland and Institute of Integrative Biology, ETH-Zurich, Zurich, Switzerland.
authors.forename: Remo
authors.initials: R
authors.lastname: Freimann
authors.affiliation: Department of Surface Waters - Research and Management, Swiss Federal Institute of Aquatic Science and Technology, Eawag, Kastanienbaum, Switzerland.
authors.forename: Helmut
authors.initials: H
authors.lastname: Bürgmann
authors.affiliation: Cary Institute of Ecosystem Studies, Millbrook, New York, United States of America.
authors.forename: Stuart E G
authors.initials: SE
authors.lastname: Findlay
authors.affiliation: Department of Aquatic Ecology, Swiss Federal Institute of Aquatic Science and Technology, Eawag, Dübendorf, Switzerland and Institute of Integrative Biology, ETH-Zurich, Zurich, Switzerland.
authors.forename: Christopher T
authors.initials: CT
authors.lastname: Robinson
mesh_terms: D001419:Bacteria / Q000254:growth & development* / Q000302:isolation & purification; D003589:Cytophaga / Q000254:growth & development / Q000302:isolation & purification; D017753:Ecosystem; D060587:Groundwater / Q000382:microbiology*; D006863:Hydrogen-Ion Concentration; D046448:Ice Cover; D009930:Organic Chemicals / Q000737:chemistry; D020560:Proteobacteria / Q000254:growth & development / Q000302:isolation & purification; D012621:Seasons; D013696:Temperature
chemical_list: D009930:Organic Chemicals