title: Microbial community composition and endolith colonization at an Arctic thermal spring are driven by calcite precipitation.
abstract: Environmental conditions shape community composition. Arctic thermal springs provide an opportunity to study how environmental gradients can impose strong selective pressures on microbial communities and provide a continuum of niche opportunities. We use microscopic and molecular methods to conduct a survey of microbial community composition at Troll Springs on Svalbard, Norway, in the high Arctic. Microorganisms there exist under a wide range of environmental conditions: in warm water as periphyton, in moist granular materials, and in cold, dry rock as endoliths. Troll Springs has two distinct ecosystems, aquatic and terrestrial, together in close proximity, with different underlying environmental factors shaping each microbial community. Periphyton are entrapped during precipitation of calcium carbonate from the spring's waters, providing microbial populations that serve as precursors for the development of endolithic communities. This process differs from most endolith colonization, in which the rock predates the communities that colonize it. Community composition is modulated as environmental conditions change within the springs. At Troll, the aquatic environments show a small number of dominant operational taxonomic units (OTUs) that are specific to each sample. The terrestrial environments show a more even distribution of OTUs common to multiple samples.
authors.affiliation: Carnegie Institution of Washington, Geophysical Laboratory, 5251 Broad Branch Road, Washington, DC, 20015, USA.
authors.forename: Verena
authors.initials: V
authors.lastname: Starke
authors.forename: Julie
authors.initials: J
authors.lastname: Kirshtein
authors.forename: Marilyn L
authors.initials: ML
authors.lastname: Fogel
authors.forename: Andrew
authors.initials: A
authors.lastname: Steele
mesh_terms: D001110:Arctic Regions; D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D002119:Calcium Carbonate / Q000737:chemistry*; D011232:Chemical Precipitation; D017753:Ecosystem; D019015:Geologic Sediments / Q000737:chemistry / Q000382:microbiology*; D045482:Hot Springs / Q000737:chemistry / Q000382:microbiology*; D008969:Molecular Sequence Data; D010802:Phylogeny
chemical_list: D002119:Calcium Carbonate