title: Novel chytrid lineages dominate fungal sequences in diverse marine and freshwater habitats.
abstract: In aquatic environments, fungal communities remain little studied despite their taxonomic and functional diversity. To extend the ecological coverage of this group, we conducted an in-depth analysis of fungal sequences within our collection of 3.6 million V4 18S rRNA pyrosequences originating from 319 individual marine (including sea-ice) and freshwater samples from libraries generated within diverse projects studying Arctic and temperate biomes in the past decade. Among the ~1.7 million post-filtered reads of highest taxonomic and phylogenetic quality, 23,263 fungal sequences were identified. The overall mean proportion was 1.35%, but with large variability; for example, from 0.01 to 59% of total sequences for Arctic seawater samples. Almost all sample types were dominated by Chytridiomycota-like sequences, followed by moderate-to-minor contributions of Ascomycota, Cryptomycota and Basidiomycota. Species and/or strain richness was high, with many novel sequences and high niche separation. The affinity of the most common reads to phytoplankton parasites suggests that aquatic fungi deserve renewed attention for their role in algal succession and carbon cycling.
authors.affiliation: Institut de Biologie Intégrative et des Systèmes (IBIS) and Centre d'Étude de la Forêt (CEF), Université Laval, Québec, Canada.
authors.forename: André M
authors.initials: AM
authors.lastname: Comeau
authors.affiliation: Centre d'Études Nordiques (CEN), Takuvik Joint International Laboratory (CNRS UMI-3376) and Département de Biologie, Université Laval, Québec, Canada.
authors.forename: Warwick F
authors.initials: WF
authors.lastname: Vincent
authors.affiliation: Institut de Biologie Intégrative et des Systèmes (IBIS) and Centre d'Étude de la Forêt (CEF), Université Laval, Québec, Canada.
authors.forename: Louis
authors.initials: L
authors.lastname: Bernier
authors.affiliation: Institut de Biologie Intégrative et des Systèmes (IBIS), Takuvik Joint International Laboratory (CNRS UMI-3376) and Département de Biologie, Université Laval, Québec, Canada.
authors.forename: Connie
authors.initials: C
authors.lastname: Lovejoy
mesh_terms: D001110:Arctic Regions; D008411:Chytridiomycota / Q000235:genetics; D017753:Ecosystem; D005618:Fresh Water / Q000382:microbiology*; D005658:Fungi / Q000235:genetics*; D046448:Ice Cover / Q000382:microbiology; D010802:Phylogeny; D010839:Phytoplankton / Q000382:microbiology; D012337:RNA, Ribosomal, 18S / Q000235:genetics; D012623:Seawater / Q000382:microbiology*
chemical_list: D012337:RNA, Ribosomal, 18S