Bennett, Sarah A. and Hansman, Roberta L. and Sessions, Alex L. and Nakamura, Ko-ichi. and Edwards, Katrina J. (2011) Tracing iron-fueled microbial carbon production within the hydrothermal plume at the Loihi seamount. Geochimica et Cosmochimica Acta, 75 (19). pp. 5526-5539. ISSN 0016-7037 http://resolver.caltech.edu/CaltechAUTHORS:20111006-104756740
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The Loihi hydrothermal plume provides an opportunity to investigate iron (Fe) oxidation and microbial processes in a system that is truly Fe dominated and distinct from mid-ocean ridge spreading centers. The lack of hydrogen sulfide within the Loihi hydrothermal fluids and the presence of an oxygen minimum zone at this submarine volcano’s summit, results in a prolonged presence of reduced Fe within the dispersing non-buoyant plume. In this study, we have investigated the potential for microbial carbon fixation within the Loihi plume. We sampled for both particulate and dissolved organic carbon in hydrothermal fluids, microbial mats growing around vents, and the dispersing plume, and carried out stable carbon isotope analysis on the particulate fraction. The δ^(13)C values of the microbial mats ranged from −23‰ to −28‰, and are distinct from those of deep-ocean particulate organic carbon (POC). The mats and hydrothermal fluids were also elevated in dissolved organic carbon (DOC) compared to background seawater. Within the hydrothermal plume, DOC and POC concentrations were elevated and the isotopic composition of POC within the plume suggests mixing between background seawater POC and a ^(13)C-depleted hydrothermal component. The combination of both DOC and POC increasing in the dispersing plume that cannot solely be the result of entrainment and DOC adsorption, provides strong evidence for in-situ microbial productivity by chemolithoautotrophs, including a likelihood for iron-oxidizing microorganisms.
|Additional Information:||© 2011 Elsevier Ltd. Received 29 November 2010; Accepted 23 June 2011. Associate editor: Tom McCollom. Available online 8 July 2011. We would like to thank the Associate editor, Tom McCollom and three anonymous reviewers, whose comments significantly improved this manuscript. We thank the captain, crew and technical support on board the Kilo Moana, KM09-23 and the ROV pilots of Jason-II, who contributed to the success of this work. We thank Olivier Rouxel, Jason Sylvan and Deb Jaisi who assisted in CTD operations and Olivier Rouxel and Rick Davis for on board processing of vent fluid and mat samples. We thank Craig Carlson for DOC measurements and Jim Moffett for access to his clean room facilities at USC. This work was supported by the NSF Microbial Observatories Program (MCB 0653265), the Moore Foundation and NSF-OCE 0648287. This is the Center for Dark Energy Biosphere Investigations contribution #106.|
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|Official Citation:||Sarah A. Bennett, Roberta L. Hansman, Alex L. Sessions, Ko-ichi. Nakamura, Katrina J. Edwards, Tracing iron-fueled microbial carbon production within the hydrothermal plume at the Loihi seamount, Geochimica et Cosmochimica Acta, Volume 75, Issue 19, 1 October 2011, Pages 5526-5539, ISSN 0016-7037, 10.1016/j.gca.2011.06.039.|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Tony Diaz|
|Deposited On:||06 Oct 2011 18:28|
|Last Modified:||06 Oct 2011 18:28|
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