title: Hydrocarbon biodegradation by Arctic sea-ice and sub-ice microbial communities during microcosm experiments, Northwest Passage (Nunavut, Canada).
abstract: The increasing accessibility to navigation and offshore oil exploration brings risks of hydrocarbon releases in Arctic waters. Bioremediation of hydrocarbons is a promising mitigation strategy but challenges remain, particularly due to low microbial metabolic rates in cold, ice-covered seas. Hydrocarbon degradation potential of ice-associated microbes collected from the Northwest Passage was investigated. Microcosm incubations were run for 15 days at -1.7°C with and without oil to determine the effects of hydrocarbon exposure on microbial abundance, diversity and activity, and to estimate component-specific hydrocarbon loss. Diversity was assessed with automated ribosomal intergenic spacer analysis and Ion Torrent 16S rRNA gene sequencing. Bacterial activity was measured by (3)H-leucine uptake rates. After incubation, sub-ice and sea-ice communities degraded 94% and 48% of the initial hydrocarbons, respectively. Hydrocarbon exposure changed the composition of sea-ice and sub-ice communities; in sea-ice microcosms, Bacteroidetes (mainly Polaribacter) dominated whereas in sub-ice microcosms, the contribution of Epsilonproteobacteria increased, and that of Alphaproteobacteria and Bacteroidetes decreased. Sequencing data revealed a decline in diversity and increases in Colwellia and Moritella in oil-treated microcosms. Low concentration of dissolved organic matter (DOM) in sub-ice seawater may explain higher hydrocarbon degradation when compared to sea ice, where DOM was abundant and composed of labile exopolysaccharides.
authors.affiliation: Fisheries and Oceans Canada, Marine Productivity Laboratory, 501 University Crescent, Winnipeg, MB R3T 2N6, Canada me.garneau@gmail.com.
authors.forename: Marie-Ève
authors.initials: MÈ
authors.lastname: Garneau
authors.affiliation: Fisheries and Oceans Canada, Marine Productivity Laboratory, 501 University Crescent, Winnipeg, MB R3T 2N6, Canada.
authors.forename: Christine
authors.initials: C
authors.lastname: Michel
authors.affiliation: Fisheries and Oceans Canada, Marine Productivity Laboratory, 501 University Crescent, Winnipeg, MB R3T 2N6, Canada.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Meisterhans
authors.affiliation: Energy, Mining and Environment, National Research Council of Canada, 6100 Royalmount Avenue, Montreal, QC H4P 2R2, Canada.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Fortin
authors.affiliation: Fisheries and Oceans Canada, Bedford Institute of Oceanography, PO Box 1006, Dartmouth, NS B2Y 4A2, Canada.
authors.forename: Thomas L
authors.initials: TL
authors.lastname: King
authors.affiliation: Energy, Mining and Environment, National Research Council of Canada, 6100 Royalmount Avenue, Montreal, QC H4P 2R2, Canada.
authors.forename: Charles W
authors.initials: CW
authors.lastname: Greer
authors.affiliation: Oceans and Atmosphere National Research Flagship, Australian Resources Research Centre, CSIRO, 26 Dick Perry Avenue, Kensington, WA 6151, Australia.
authors.forename: Kenneth
authors.initials: K
authors.lastname: Lee
mesh_terms: D020561:Alphaproteobacteria / Q000235:genetics; D001110:Arctic Regions; D041963:Bacteroidetes / Q000235:genetics; D001673:Biodegradation, Environmental; D002170:Canada; D041965:Flavobacteriaceae / Q000235:genetics; D006838:Hydrocarbons / Q000378:metabolism*; D046448:Ice Cover / Q000382:microbiology*; D020957:Nunavut; D010578:Petroleum / Q000378:metabolism; D059392:Petroleum Pollution; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012623:Seawater / Q000382:microbiology; D014874:Water Pollutants, Chemical / Q000378:metabolism*
chemical_list: D006838:Hydrocarbons; D010578:Petroleum; D012336:RNA, Ribosomal, 16S; D014874:Water Pollutants, Chemical
keywords: 16S ribosomal RNA gene sequencing; Arctic; bioremediation; hydrocarbon biodegradation; microbial community fingerprinting; sea ice