BACKGROUND: 

NeMO Project Description 

Mission 

1998 Plans 

Technology (ROV, ships, etc.) 

Future Plans 

Axial 1998 "Eruption" Page

Other 1998 Axial cruise reports

EXPEDITION: 
Science Objectives

Dive/Cruise Plan

Participants

Highlights from Sea 

Calendar 
Today's Science News 
Participant Perspective 
Teacher Logbook 

EDUCATION: 
Curriculum 
Teacher Observations 
Questions/Answers from sea 

MULTIMEDIA:
(video clips, animations, sounds)

RELATED LINKS 

The 1998 NeMO expedition will be on board the NOAA ship Ron Brown from August 24 to September 20. The ROV ROPOS will be the primary tool for observing and sampling the seafloor as well as for manipulating other instrumentation.

The research cruise consists of 23 dive days and 3 transit days. Below is a summary of the scientific objectives that were funded by the supporting agencies. In addition to these goals, there will be interest in documenting any changes resulting from the earthquake swarm and intrusion/eruption that occurred at Axial in January 1998.

The scientific research during the NeMO cruise is multi-disciplinary. That means that scientist from many different fields (geology, chemistry, biology, oceanography, geophysics) are all working together toward a set of common goals. Nevertheless, specific objectives can be broken down by discipline:

Goals by Discipline:

• Chemistry/Microbiology of Subsurface Biosphere
• Macrobiology/Ecology
• Microbiology Processes at Vents
• Geology/Hydrothermal Linkages

Chemistry/Microbiology of Subsurface Biosphere

The chemistry program aims to find relationships between the temperature and chemical composition of selected hydrothermal vents with the kind of microorganisms thriving in them. The specific aim is to understand what the subsurface environment is like.

Objectives & key questions:
1) Define geochemical niches in different hydrothermal vent sites.

2) Look for evidence of chemical reaction or metabolism by microorganisms within hydrothermal fluid samples.

3) Culture microbes from well-characterized environments.

4) Assess diversity and population structure by genetic techniques.

5) Relate chemistry and microbiology to geological structure and plumbing system.

Measurements Planned:
Shipboard:

SUAVE in situ: CTD, Fe, Mn, H2S, (pH)
Discrete shipboard: H2S, Si(OH)4, NH3, pH
Ion Chromatograph: Cl, SO4 , Li, Na, K, Mg, Ca
Organic acids (formate, acetate, propionate)
Critical volatiles (H , O , CH , CO ) by GC (B. McLaughlin)

On shore:

Transition metals and trace elements, frozen samples for NO3, DOC (at UW)
He and rare gases (Lupton)
Sr isotopes (with B. Nelson UW)
Particulate elemental concentrations and particle morphologies by XRF and SEM
POC
Isotopes of C, N, S
Other organic compounds

Monitoring:

Osmosamplers (Year-long deployments)
SUAVE (short-term deployment)

Requirements:

Extensive use of fluid sampler, SUAVE
Deployment of osmosamplers

Macrobiology/Ecology

The microbiology/ecology program will focus on the communities of larger animals that live in and around hydrothermal vent sites.

Objectives and key questions:
General:
1) What is the role of system stability: vent community diversity compared to CoAxial and Cleft?
2) What are the local diversity patterns with respect to geological and chemical gradients ??
3) What are the metapopulation dynamics in the caldera?
4) How do biota and chemistry covary?

Specific:
1) Diversity of the Axial Seamount vent communities:

Does Species composition vary markedly over the four major Axial sites?
How does the Axial species pool compare to Cleft and CoAxial?
What does temporal variability look like at Axial?

Correlate information on water/microbial conditions and animal distribution over the caldera
initial focus on the polychaetes as they display variability over the seamount

Requirements:
Sampling of animals exactly where chemical parameters examined

Microbial Processes at Vents

The microbiology program will characterize the different vent habitats above the seafloor and relate this to the microorganisms living there.

Processes:
1) Habitat conditions and behavior of sulphide worms

Goals:
Map high temperature habitat with SUAVE
Collect spires
Video surveys

20 scans
30 min. Video
Time-lapse camera deployment for a day or two

Measure low-temperature microbial abundance and diversity
Important aspect of vent community characterization

Some time for testing and adjusting system, in conjunction with SUAVE surveys

Interpret ranges of C and N isotopes in select species in different conditions of venting

Collection of faunal samples where SUAVE and/or fluid samples taken (also fits with Tunnicliffe group goals)

Mineral, chemical, and microbial characterization of oxide mounds around ASHES
Mapping of mounds

SUAVE, time for collection of samples (with PacMan, Slurpgun, manipulator)

Geological/Hydrothermal Linkages

The geology program will look at the different kinds of geologic structures that host hydrothermal vents.

Goals:
(1) Document relationships between volcanic activity, tectonic setting and temporal evolution of hydrothermal systems
(2) Measure effects of diking on horizontal strain field and hydrothermal system
(3) Look for relationships between seismicity and temperature changes at hydrothermal vents

Tasks:
1) Detailed mapping of several hydrothermal systems at the summit of Axial, including:

• the southwest wall (ASHES and vicinity)
• upper south rift zone
• the junction between east caldera wall and south rift zone
• the upper north rift zone
• the CASM site

2) Time-series of horizontal strain changes on Axial Rift zone(s)

Survey 1996-98 site of extensometer deployment
Recover extensometers plus refurbish
Redeploy 5 extensometers (1 year), probably at same site

Requirements:
Dedicated dive time, elevator to recover and redeploy extensometers

3) Geologic/hydrothermal time series

Look at nature of and coherence of temperature changes in selected hydrothermal vents with seismicity (recorded during a separate OBS experiment by SIO researchers) Do earthquakes cause changes in the output of individual vents?

Requirements:
Deployment of 4 HOBO probes (hi-temp), and up to 10 low-temp probes at diffuse vents at range of geologic settings and over maximum spatial separation (some may be put in with ALVIN in July)

Additionally, activities not requiring the ROV (during down time):
• a rock-coring program
• mooring deployments
• CTD (conductivity/temperature/depth) casts or tows
• multibeam bathymetric surveys

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