Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
  • Data Processing Description
• Data Files
• Related Publications
• Related Datasets
• Parameters
• Instruments
• Deployments
• Project Information
• Funding

- All fluids were collected using isobaric gas-tight fluid samplers (Seewald et al., 2002).
- Temperature was measured during sample collection using a type-J thermocouple attached to the inlet snorkel. Reported values are maximums observed during sample collection.

Analytical methods:
pH: Ag/AgCl combination reference electrode
Na+, K+, Ca2+, Mg2+, Cl-, Br-, SO42- : ion chromatography with suppressed conductivity detectionCH4: gas chromatography with flame ionization detection
H2: gas chromatography with thermal conductivity detection

BCO-DMO Processing:
- Added conventional header with dataset name, PI name, version date
- Modified parameter names to conform with BCO-DMO naming conventions
- Replaced blanks (missing data) and 'nd' to indicate 'no data'
- Added cruise_id column
- Replaced spaces with underscores (vent_site)
- Changed format of lat and lon to degrees north and east

Extreme environmental gradients exist at deep-sea hydrothermal vents where high temperature, low pH and reduced fluids mix with cold oxygenated seawater. This results in a plethora of microbes taking advantage of abundantly available microniches. From small subunit (16S) rRNA gene surveys and directed enrichment culturing of vent deposits from many sites, patterns in diversity are emerging that suggest that geochemical processes, particularly those that affect fluid pH, play a fundamental role in regulating microbial diversity and community composition.

This is a three year study at vent fields along the Eastern Lau Spreading Center (ELSC) to investigate the relationship between vent geochemistry and microbial community dynamics. The ELSC was chosen because it provides large and systematic changes in fluid and rock geochemistry, spreading rate, magmatic/tectonic processes, and proximity to the volcanic arc over its relatively short length of 397 km. The individual vent fields therefore provide excellent natural laboratories for exploring, in depth, the factors that influence the diversity and relationships of microbial communities associated with actively forming deep-sea hydrothermal deposits. The study will be carried out at 3 geochemically different hydrothermal fields along the ELSC. The scientists will document microbial community composition and diversity associated with hydrothermal deposits from each area for comparison with data obtained in 2009 and 2005. The close proximity of these geochemically distinct vent areas within the ELSC provides an ideal opportunity to investigate the effect of vent fluid and deposit geochemistry on the structure and function of microbial communities, as well as the specific roles of individual populations, associated with active hydrothermal deposits. The investigators hypothesize that, given the extreme environmental characteristics (e.g., low fluid pH and high iron at Mariner), they will see distinct differences in the metagenomes and particularly in the metatranscriptomes among the Kilo Moana, ABE and Mariner vent fields.

The specific objectives are to:
1) Link geochemical and microbial dynamics along the ELSC (from 2005-­2013);
2) Use of metagenomic and transcriptomic data to explore biogeochemical cycles that are regulating the functional roles of the microbial communities in vent fields along the ELSC; and
3) Use the metagenomic information to enrich for targeted novel Thermoprotei and acidophiles. Active hydrothermal metal sulfide deposits and fluid samples will be collected from the vent fields along the ELSC.

Bar-coded pyrosequencing of archaeal and bacterial 16S rRNA amplicons will be obtained for over eighty samples. The geochemical environment of the chimneys will be modeled to determine in situ geochemical conditions. These values will be used in statistical analyses to explore the factors affecting the observed differences in the communities. Using the 16S rRNA gene 454 pyrotags coupled with the geochemical characterization, specific samples will be selected for metagenomic and metatranscriptomic analyses (1-3 of each per site). The molecular information will be used to target specific samples that: (i) harbor novel unclassified diversity; (ii) have vent endemic lineages; and (iii) have acidophilic relatives from terrestrial systems, for enrichment culturing (using the geochemistry to help constrain culturing conditions).