Table of Contents

• Dataset Description
  • Methods & Sampling
  • Data Processing Description
• Data Files
• Parameters
• Instruments
• Deployments
• Project Information
• Funding

Microbial cell abundance and carbon, nitrogen, and sulfur content from venting fluids and microbial mats at Axial Seamount, 2011. Samples collected on cruise AT18-08.

Diffuse fluids were collected from newly discovered snowblower vents at Axial Seamount in late July 2011 with the ROV Jason II using the hydrothermal fluid and particle sampler (Butterfield et al., 2004). White and orange flocculent materials were collected on the subsequent University of Washington Visions' 11 cruise, in support of the Regional Scale Nodes component of the Ocean Observatories Initiative in August 2011. White flocculent material was collected from the orifice of the Subway snowblower vent on dives R1467 (White Floc 1) and R1472 (White Floc 2) and orange flocculent material was collected on the seafloor distal to Marker 33 during dive R1472 where it coated freshly deposited basalt. All of the fluid and floc samples analyzed in this study are from a small area in the south rift zone at the southeastern edge of Axial Caldera, with the exception of background seawater which was collected outside of the caldera.

Subsamples of flocculent material were viewed under phase contrast, fixed and stained with DAPI for cell counting via epiflourescent microscopy, or fixed for scanning electron microscopy (SEM) with elemental detection system (EDS) on a Zeiss Supra 40VP. White and orange flocs were fixed with 2.5% glutaldehyde for both cell counts and SEM. Preserved whole fluids were also stained with DAPI for cell counts.

Bulk carbon and nitrogen were measured using a Thermo Scientific CN Analyzer (Model Flash 2000) from subsamples of flocculent material dried at 50–60 degrees C for 2 days. A standard curve for bulk carbon and nitrogen was made using aspartic acid as a standard and acetanilide and apple leaf as standard curve checks. Bulk sulfur was measured using a LECO S632 Sulfur Analyzer from subsamples of flocculent material dried in a dessicator for 4 days and supplemented with sterile sea sand (Fisher) to meet minimum volume requirements. A standard curve for bulk sulfur was made using coal with known sulfur content provided by LECO.

Related references:
Meyer, J.L., Akerman, N.H., Proskurowski, G. and J.A. Huber. 2013. Microbiological characterization of post-eruption "snowblower" vents at Axial Seamount, Juan de Fuca Ridge. Frontiers in Microbiology. 4:153. doi:10.3389/fmicb.2013.00153

Two subsamples were analyzed for each floc sample and replicate readings were averaged for all bulk C, N, and S measurements. ± 95% confidence levels for total cell counts are reported.

BCO-DMO Processing:
- modified parameter names to conform with BCO-DMO naming conventions;
- replaced "no data" with "nd";
- removed "m" (meters) in depth column;
- changed format of date to YYYYmmdd;
- replaced commas with semi-colons;
- Added cruise_id field.

Collaborative Research: Function, activity, and adaptation of microbial communities in geochemically diverse subseafloor habitats

The integration of both laboratory and field-based chemical and microbiological measurements into a quantitative predictive framework is crucial to understanding the microbial ecology of marine systems. This project work will provide a quantitative assessment of the functional diversity, activity, and physiological adaptation of microbial communities in geochemically diverse subseafloor habitats. Results will guide development of models for linking biogeochemical processes with particular microbial communities at deep-sea hydrothermal vents, with implications for other marine habitats as well. The focus of the effort is at Axial Seamount, a well-studied, active, deep-sea hydrothermal seamount in the NE Pacific Ocean. Samples already collected from Axial, along with a field program in Year 2, will serve as the foundation for the three objectives, which are to:

1. Determine and quantify the functional diversity and activity (expression) of key subseafloor microbial lineages at Axial Seamount.

2. Determine physiological adaptations to the subseafloor habitat by quantifying the growth response of Axial Seamount isolates to in-situ geochemical parameters.

3. Develop a quantitative predictive framework for linking particular types of geochemical vent conditions with specific microbial functional groups and activities at Axial Seamount.

Specific outcomes of this project include the creation of a comprehensive quantitative microbiological and chemical dataset on diffuse and adjacent high-temperature vents within Axial Seamount. This database will include chemical measurements (gases, nutrients, metals, isotopes, and calculated Gibbs free energies) relevant to microbial metabolic processes that can be compared to microbiological data (abundance and activity of microbial lineages and functional genes, growth rates of subseafloor isolates at relevant environmental conditions) using statistical analysis to identify how specific microbial activity is linked to the geochemical environment. This project builds on previous studies of microbial population structure and geochemical measurements at Axial Seamount and addresses critical gaps in current knowledge and understanding that are impeding progress of modeling hydrothermal systems. Results will increase understanding of deep-sea hydrothermal ecosystems as well as provide new insights into controls on the distribution and activity of marine microbial communities throughout the world's oceans.

NeMO10 TN253 Cruise Report