title: Rare but active taxa contribute to community dynamics of benthic biofilms in glacier-fed streams.
abstract: Glaciers harbour diverse microorganisms, which upon ice melt can be released downstream. In glacier-fed streams microorganisms can attach to stones or sediments to form benthic biofilms. We used 454-pyrosequencing to explore the bulk (16S rDNA) and putatively active (16S rRNA) microbial communities of stone and sediment biofilms across 26 glacier-fed streams. We found differences in community composition between bulk and active communities among streams and a stronger congruence between biofilm types. Relative abundances of rRNA and rDNA were positively correlated across different taxa and taxonomic levels, but at lower taxonomic levels, the higher abundance in either the active or the bulk communities became more apparent. Here, environmental variables played a minor role in structuring active communities. However, we found a large number of rare taxa with higher relative abundances in rRNA compared with rDNA. This suggests that rare taxa contribute disproportionately to microbial community dynamics in glacier-fed streams. Our findings propose that high community turnover, where taxa repeatedly enter and leave the 'seed bank', contributes to the maintenance of microbial biodiversity in harsh ecosystems with continuous environmental perturbations, such as glacier-fed streams.
authors.affiliation: Department of Limnology and Bio-Oceanography, University of Vienna, Althanstr. 14, A-1090, Vienna, Austria.
authors.forename: Linda
authors.initials: L
authors.lastname: Wilhelm
authors.forename: Katharina
authors.initials: K
authors.lastname: Besemer
authors.forename: Christina
authors.initials: C
authors.lastname: Fasching
authors.forename: Tim
authors.initials: T
authors.lastname: Urich
authors.forename: Gabriel A
authors.initials: GA
authors.lastname: Singer
authors.forename: Christopher
authors.initials: C
authors.lastname: Quince
authors.forename: Tom J
authors.initials: TJ
authors.lastname: Battin
mesh_terms: D001419:Bacteria / Q000145:classification* / Q000235:genetics; D044822:Biodiversity; D018441:Biofilms / Q000254:growth & development; D017753:Ecosystem; D019015:Geologic Sediments / Q000382:microbiology; D059014:High-Throughput Nucleotide Sequencing; D046448:Ice Cover / Q000382:microbiology*; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D014871:Water Microbiology
chemical_list: D012336:RNA, Ribosomal, 16S