title: Upstream Freshwater and Terrestrial Sources Are Differentially Reflected in the Bacterial Community Structure along a Small Arctic River and Its Estuary.
abstract: Glacier melting and altered precipitation patterns influence Arctic freshwater and coastal ecosystems. Arctic rivers are central to Arctic water ecosystems by linking glacier meltwaters and precipitation with the ocean through transport of particulate matter and microorganisms. However, the impact of different water sources on the microbial communities in Arctic rivers and estuaries remains unknown. In this study we used 16S rRNA gene amplicon sequencing to assess a small river and its estuary on the Disko Island, West Greenland (69°N). Samples were taken in August when there is maximum precipitation and temperatures are high in the Disko Bay area. We describe the bacterial community through a river into the estuary, including communities originating in a glacier and a proglacial lake. Our results show that water from the glacier and lake transports distinct communities into the river in terms of diversity and community composition. Bacteria of terrestrial origin were among the dominating OTUs in the main river, while the glacier and lake supplied the river with water containing fewer terrestrial organisms. Also, more psychrophilic taxa were found in the community supplied by the lake. At the river mouth, the presence of dominant bacterial taxa from the lake and glacier was unnoticeable, but these taxa increased their abundances again further into the estuary. On average 23% of the estuary community consisted of indicator OTUs from different sites along the river. Environmental variables showed only weak correlations with community composition, suggesting that hydrology largely influences the observed patterns.
authors.affiliation: Center for Biosustainability, Technical University of DenmarkHoersholm, Denmark; DTU Bioinformatics, Technical University of DenmarkKgs. Lyngby, Denmark; Center for Permafrost, University of CopenhagenCopenhagen, Denmark.
authors.forename: Aviaja L
authors.initials: AL
authors.lastname: Hauptmann
authors.affiliation: Center for Permafrost, University of Copenhagen Copenhagen, Denmark.
authors.forename: Thor N
authors.initials: TN
authors.lastname: Markussen
authors.affiliation: Center for Permafrost, University of CopenhagenCopenhagen, Denmark; Department of Ecology, Faculty of Science, Charles UniversityPrague, Czech Republic.
authors.forename: Marek
authors.initials: M
authors.lastname: Stibal
authors.affiliation: Center for Permafrost, University of Copenhagen Copenhagen, Denmark.
authors.forename: Nikoline S
authors.initials: NS
authors.lastname: Olsen
authors.affiliation: Center for Permafrost, University of Copenhagen Copenhagen, Denmark.
authors.forename: Bo
authors.initials: B
authors.lastname: Elberling
authors.affiliation: Chr. Hansen A/S Hoersholm, Denmark.
authors.forename: Jacob
authors.initials: J
authors.lastname: Bælum
authors.affiliation: DTU Bioinformatics, Technical University of Denmark Kgs. Lyngby, Denmark.
authors.forename: Thomas
authors.initials: T
authors.lastname: Sicheritz-Pontén
authors.affiliation: Center for Permafrost, University of CopenhagenCopenhagen, Denmark; Department of Environmental Science, Aarhus UniversityRoskilde, Denmark.
authors.forename: Carsten S
authors.initials: CS
authors.lastname: Jacobsen
keywords: Greenland; arctic; bacterial community; biodiversity; freshwater network; polar environments