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ArticleA distinct and active bacterial community in cold oxygenated fluids circulating beneath the western flank of the Mid-Atlantic ridge(Nature Publishing Group, 2016-03-03) Meyer, Julie L. ; Jaekel, Ulrike ; Tully, Benjamin J. ; Glazer, Brian T. ; Wheat, C. Geoffrey ; Lin, Huei-Ting ; Hsieh, Chih-Chiang ; Cowen, James P. ; Hulme, Samuel M. ; Girguis, Peter R. ; Huber, Julie A.The rock-hosted, oceanic crustal aquifer is one of the largest ecosystems on Earth, yet little is known about its indigenous microorganisms. Here we provide the first phylogenetic and functional description of an active microbial community residing in the cold oxic crustal aquifer. Using subseafloor observatories, we recovered crustal fluids and found that the geochemical composition is similar to bottom seawater, as are cell abundances. However, based on relative abundances and functional potential of key bacterial groups, the crustal fluid microbial community is heterogeneous and markedly distinct from seawater. Potential rates of autotrophy and heterotrophy in the crust exceeded those of seawater, especially at elevated temperatures (25°C) and deeper in the crust. Together, these results reveal an active, distinct, and diverse bacterial community engaged in both heterotrophy and autotrophy in the oxygenated crustal aquifer, providing key insight into the role of microbial communities in the ubiquitous cold dark subseafloor biosphere. An Author Correction to this article was published on 16 April 2020
DatasetDOC, POC, d13C-POC, PN from a diffuse vent in West Mata sampled in May 2009 using ROV Jason II deployed from R/V Thomas Thompson.(Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: firstname.lastname@example.org, 2021-04-15) Lin, Huei-Ting ; Butterfield, David A. ; Baker, Edward T. ; Resing, Joseph A. ; Huber, Julie ; Cowen, JamesDOC, POC, d13C-POC, PN from a diffuse vent in West Mata sampled in May 2009 using ROV Jason II deployed from R/V Thomas Thompson. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/844580
ArticleSampling of basement fluids via circulation obviation retrofit kits (CORKs) for dissolved gases, fluid fixation at the seafloor, and the characterization of organic carbon(Elsevier, 2020-08-15) Lin, Huei-Ting ; Hsieh, Chih-Chiang ; Repeta, Daniel J. ; Rappe, Michael S.The advanced instrumented GeoMICROBE sleds (Cowen et al., 2012) facilitate the collection of hydrothermal fluids and suspended particles in the subseafloor (basaltic) basement through Circulation Obviation Retrofit Kits (CORKs) installed within boreholes of the Integrated Ocean Drilling Program. The main components of the GeoMICROBE can be converted into a mobile pumping system (MPS) that is installed on the front basket of a submersible or remotely-operated-vehicle (ROV). Here, we provide details of a hydrothermal fluid-trap used on the MPS, through which a gastight sampler can withdraw fluids. We also applied the MPS to demonstrate the value of fixing samples at the seafloor in order to determine redox-sensitive dissolved iron concentrations and speciation measurements. To make the best use of the GeoMICROBE sleds, we describe a miniature and mobile version of the GeoMICROBE sled, which permits rapid turn-over and is relatively easy for preparation and operation. Similar to GeoMICROBE sleds, the Mobile GeoMICROBE (MGM) is capable of collecting fluid samples, filtration of suspended particles, and extraction of organics. We validate this approach by demonstrating the seafloor extraction of hydrophobic organics from a large volume (247L) of hydrothermal fluids. • We describe the design of a hydrothermal fluid-trap for use with a gastight sampler, as well as the use of seafloor fixation, through ROV- or submersible assisted mobile pumping systems. • We describe the design of a Mobile GeoMICROBE (MGM) that enhances large volume hydrothermal fluid sampling, suspended particle filtration, and organic matter extraction on the seafloor. • We provide an example of organic matter extracted and characterized from hydrothermal fluids via a MGM.
ArticleOrganic biogeochemistry in West Mata, NE Kau hydrothermal vent fields(American Geophysical Union, 2021-03-17) Lin, Huei-Ting ; Butterfield, David A. ; Baker, Edward T. ; Resing, Joseph A. ; Huber, Julie A. ; Cowen, James P.The impact of submarine hydrothermal systems on organic carbon in the ocean—one of the largest fixed carbon reservoirs on Earth—could be profound. Yet, different vent sites show diverse fluid chemical compositions and the subsequent biological responses. Observations from various vent sites are to evaluate hydrothermal systems' impact on the ocean carbon cycle. A response cruise in May 2009 to an on-going submarine eruption at West Mata Volcano, northeast Lau Basin, provided an opportunity to quantify the organic matter production in a back-arc spreading hydrothermal system. Hydrothermal vent fluids contained elevated dissolved organic carbon, particulate organic carbon (POC), and particulate nitrogen (PN) relative to background seawater. The δ13C-POC values for suspended particles in the diffuse vent fluids (−15.5‰ and −12.3‰) are distinct from those in background seawater (−23 ± 1‰), indicative of unique carbon synthesis pathways of the vent microbes from the seawater counterparts. The first dissolved organic nitrogen concentrations reported for diffuse vents were similar to or higher than those for background seawater. Enhanced nitrogen fixation and denitrification removed 37%–89% of the total dissolved nitrogen in the recharging background seawater in the hydrothermal vent flow paths. The hydrothermal plume samples were enriched in POC and PN, indicating enhanced biological production. The total “dark” organic carbon production within the plume matches the thermodynamic prediction based on available reducing chemical substances supplied to the plume. This research combines the measured organic carbon contents with thermodynamic modeled results and demonstrates the importance of hydrothermal activities on the water column carbon production in the deep ocean.