title: Nitrate addition has minimal short-term impacts on greenland ice sheet supraglacial prokaryotes.
abstract: Tropospheric nitrate levels are predicted to increase throughout the 21stcentury, with potential effects on terrestrial ecosystems, including the Greenland ice sheet (GrIS). This study considers the impacts of elevated nitrate concentrations on the abundance and composition of dominant bulk and active prokaryotic communities sampled from in situ nitrate fertilization plots on the GrIS surface. Nitrate concentrations were successfully elevated within sediment-filled meltwater pools, known as cryoconite holes; however, nitrate additions applied to surface ice did not persist. Estimated bulk and active cryoconite community cell abundance was unaltered by nitrate additions when compared to control holes using a quantitative PCR approach, and nitrate was found to have a minimal affect on the dominant 16S rRNA gene-based community composition. Together, these results indicate that sampled cryoconite communities were not nitrate limited at the time of sampling. Instead, temporal changes in biomass and community composition were more pronounced. As these in situ incubations were short (6 weeks), and the community composition across GrIS surface ice is highly variable, we suggest that further efforts should be considered to investigate the potential long-term impacts of increased nitrate across the GrIS.
authors.affiliation: Department of Geochemistry, Geological Survey of Denmark and Greenland (GEUS), Øster Voldgade 10, DK-1350, Copenhagen, Denmark.|Center for Permafrost (CENPERM), University of Copenhagen, Øster Voldgade 10, DK-1350, Copenhagen, Denmark.|Institute of Biological, Environmental & Rural Sciences (IBERS), Aberystwyth University, Penglais, Aberystwyth, SY23 3FL, UK.
authors.forename: Karen A
authors.initials: KA
authors.lastname: Cameron
authors.affiliation: Department of Geochemistry, Geological Survey of Denmark and Greenland (GEUS), Øster Voldgade 10, DK-1350, Copenhagen, Denmark.|Center for Permafrost (CENPERM), University of Copenhagen, Øster Voldgade 10, DK-1350, Copenhagen, Denmark.|Department of Ecology Faculty of Science, Charles University, Viničná 7, Prague, 128 43, Czech Republic.
authors.forename: Marek
authors.initials: M
authors.lastname: Stibal
authors.affiliation: Bristol Glaciology Centre, School of Geographical Sciences, University of Bristol, University Road, Bristol, BS8 1SS, UK.
authors.forename: Nathan
authors.initials: N
authors.lastname: Chrismas
authors.affiliation: Department of Glaciology and Climate, Geological Survey of Denmark and Greenland (GEUS), Øster Voldgade 10, Copenhagen, DK-1350, Denmark.
authors.forename: Jason
authors.initials: J
authors.lastname: Box
authors.affiliation: Center for Permafrost (CENPERM), University of Copenhagen, Øster Voldgade 10, DK-1350, Copenhagen, Denmark.|Department of Environmental Science, Aarhus University, Frederiksborgvej 399, Roskilde, DK-4000, Denmark.
authors.forename: Carsten S
authors.initials: CS
authors.lastname: Jacobsen
mesh_terms: D058448:Biota / Q000187:drug effects*; D016000:Cluster Analysis; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D006116:Greenland; D046448:Ice Cover / Q000382:microbiology*; D009566:Nitrates / Q000378:metabolism*; D010802:Phylogeny; D011387:Prokaryotic Cells / Q000145:classification* / Q000378:metabolism*; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA
chemical_list: D004275:DNA, Ribosomal; D009566:Nitrates; D012336:RNA, Ribosomal, 16S