title: Nutrient treatments alter microbial mat colonization in two glacial meltwater streams from the McMurdo Dry Valleys, Antarctica.
abstract: Microbial mats are abundant in many alpine and polar aquatic ecosystems. With warmer temperatures, new hydrologic pathways are developing in these regions and increasing dissolved nutrient fluxes. In the McMurdo Dry Valleys, thermokarsting may release both nutrients and sediment, and has the potential to influence mats in glacial meltwater streams. To test the role of nutrient inputs on community structure, we created nutrient diffusing substrata (NDS) with agar enriched in N, P and N + P, with controls, and deployed them into two Dry Valley streams. We found N amendments (N and N + P) to have greater chlorophyll-a concentrations, total algal biovolume, more fine filamentous cyanobacteria and a higher proportion of live diatoms than other treatments. Furthermore, N treatments were substantially elevated in Bacteroidetes and the small diatom, Fistulifera pelliculosa. On the other hand, species richness was almost double in P and N + P treatments over others, and coccoid green algae and Proteobacteria were more abundant in both streams. Collectively, these data suggest that nutrients have the potential to stimulate growth and alter community structure in glacial meltwater stream microbial mats, and the recent erosion of permafrost and accelerated glacial melt will likely impact resident biota in polar lotic systems here and elsewhere.
authors.affiliation: Institute of Arctic and Alpine Research, University of Colorado, 1560 30th Street, Boulder, CO 80303, USA Faculty of Science, Department of Ecology, Charles University in Prague, Viničná 7, 12844 Prague 2, Prague, Czech Republic tyler.j.kohler@gmail.com.
authors.forename: Tyler J
authors.initials: TJ
authors.lastname: Kohler
authors.affiliation: Department of Biology, University of New Mexico, Albuquerque, NM 87131, USA.
authors.forename: David J
authors.initials: DJ
authors.lastname: Van Horn
authors.affiliation: Institute of Arctic and Alpine Research, University of Colorado, 1560 30th Street, Boulder, CO 80303, USA.
authors.forename: Joshua P
authors.initials: JP
authors.lastname: Darling
authors.affiliation: Department of Biology, University of New Mexico, Albuquerque, NM 87131, USA.
authors.forename: Cristina D
authors.initials: CD
authors.lastname: Takacs-Vesbach
authors.affiliation: Institute of Arctic and Alpine Research, University of Colorado, 1560 30th Street, Boulder, CO 80303, USA.
authors.forename: Diane M
authors.initials: DM
authors.lastname: McKnight
mesh_terms: D000864:Antarctic Regions; D058448:Biota; D002734:Chlorophyll / Q000032:analysis; D000077194:Chlorophyll A; D000460:Chlorophyta / Q000378:metabolism*; D000458:Cyanobacteria / Q000302:isolation & purification / Q000378:metabolism*; D017377:Diatoms / Q000302:isolation & purification / Q000378:metabolism*; D017753:Ecosystem; D046448:Ice Cover / Q000382:microbiology; D009584:Nitrogen / Q000032:analysis*; D010758:Phosphorus / Q000032:analysis*; D020560:Proteobacteria / Q000302:isolation & purification / Q000378:metabolism*; D045483:Rivers / Q000382:microbiology; D013696:Temperature
chemical_list: D002734:Chlorophyll; D010758:Phosphorus; D009584:Nitrogen; D000077194:Chlorophyll A
keywords: C:N:P; cyanobacteria; diatom; permafrost; polar region; thermokarst