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.
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2011 Copyright the Authors and International Society for Microbial Ecology
Edwards, Katrina J.; Glazer, B. T.; Rouxel, Olivier J.; Bach, Wolfgang; Emerson, D.; Davis, Russ E.; Toner, Brandy M.; Chan, C. S.; Tebo, B. M.; Staudigel, Hubert; and Moyer, Craig L., "Ultra-diffuse Hydrothermal Venting Supports Fe-oxidizing Bacteria and Massive Umber Deposition at 5000 m off Hawaii" (2011). Biology Faculty and Staff Publications. 69.
Subjects - Topical (LCSH)
Hydrothermal vents--Microbiology--Hawaii; Microbial mats--Hawaii; Proteobacteria--Research
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