title: Ultra-diffuse hydrothermal venting supports Fe-oxidizing bacteria and massive umber deposition at 5000 m off Hawaii.
abstract: A novel hydrothermal field has been discovered at the base of Lōihi Seamount, Hawaii, at 5000 mbsl. Geochemical analyses demonstrate that 'FeMO Deep', while only 0.2 °C above ambient seawater temperature, derives from a distal, ultra-diffuse hydrothermal source. FeMO Deep is expressed as regional seafloor seepage of gelatinous iron- and silica-rich deposits, pooling between and over basalt pillows, in places over a meter thick. The system is capped by mm to cm thick hydrothermally derived iron-oxyhydroxide- and manganese-oxide-layered crusts. We use molecular analyses (16S rDNA-based) of extant communities combined with fluorescent in situ hybridizations to demonstrate that FeMO Deep deposits contain living iron-oxidizing Zetaproteobacteria related to the recently isolated strain Mariprofundus ferroxydans. Bioenergetic calculations, based on in-situ electrochemical measurements and cell counts, indicate that reactions between iron and oxygen are important in supporting chemosynthesis in the mats, which we infer forms a trophic base of the mat ecosystem. We suggest that the biogenic FeMO Deep hydrothermal deposit represents a modern analog for one class of geological iron deposits known as 'umbers' (for example, Troodos ophilolites, Cyprus) because of striking similarities in size, setting and internal structures.
authors.affiliation: Geomicrobiology Group, Marine Environmental Biology Section, Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA. kje@usc.edu
authors.forename: Katrina J
authors.initials: KJ
authors.lastname: Edwards
authors.forename: B T
authors.initials: BT
authors.lastname: Glazer
authors.forename: O J
authors.initials: OJ
authors.lastname: Rouxel
authors.forename: W
authors.initials: W
authors.lastname: Bach
authors.forename: D
authors.initials: D
authors.lastname: Emerson
authors.forename: R E
authors.initials: RE
authors.lastname: Davis
authors.forename: B M
authors.initials: BM
authors.lastname: Toner
authors.forename: C S
authors.initials: CS
authors.lastname: Chan
authors.forename: B M
authors.initials: BM
authors.lastname: Tebo
authors.forename: H
authors.initials: H
authors.lastname: Staudigel
authors.forename: C L
authors.initials: CL
authors.lastname: Moyer
mesh_terms: D004269:DNA, Bacterial / Q000235:genetics; D004275:DNA, Ribosomal / Q000235:genetics; D006254:Hawaii; D060086:Hydrothermal Vents / Q000382:microbiology*; D007501:Iron / Q000378:metabolism*; D010084:Oxidation-Reduction; D020560:Proteobacteria / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D012623:Seawater / Q000737:chemistry / Q000382:microbiology*; D013696:Temperature
chemical_list: D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D007501:Iron