Characterization of marine microbial communities around an Arctic seabed hydrocarbon seep at Scott Inlet, Baffin Bay

Seabed hydrocarbon seeps present natural laboratories for investigating responses of marine ecosystems to petroleum input. A seep near Scott Inlet, Baffin Bay, was visited in situ observations and sampling the summer 2018. Video evidence an active confirmed by methane analysis overlying water column, which is 260 m at this site. Elevated concentrations bottom above down current from decreased background seawater levels mid-water column >150 seafloor. Seafloor microbial mats morphologically resembling sulfide-oxidizing bacteria surrounded areas bubble ebullition. Calcareous tube worms, brittle stars, shrimp, sponges, sea anemones, urchins, small fish soft corals were observed seep, with showing incorporation. Sediment communities included putative methane-oxidizing Methyloprofundus , sulfate-reducing Desulfobulbaceae Sulfurovum . metabolic gene diagnostic aerobic methanotrophs ( pmoA ) detected sediment epicentre up 5 km away. Both 16S rRNA amplicon sequencing revealed that pelagic oriented along geologic basement rise associated seepage (running SW NE) differed off-axis Relative abundances hydrocarbon-degrading elevated seep. Detection bacterial clades typically oxidation highlights importance Arctic mitigating emissions sources. • Methane liquid hydrocarbons are seeping seafloor Inlet. Cold benthic megafauna typical sediments. Soft incorporate into biomass. High drops upper column. Pelagic persist cold