Leg 6 Researchers

Click on any name below to read an interview.

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David Caress Rendy Keaten Margaret K. Tivey
Alexandra Chee Antoine Page Bill Ussler
Mike Foster Charlie Paull Jorge Ledesma Vazquez
Gary Greene Debra Stakes



Davis Caress
(top of page)
MBARI Senior Research Specialist



What is your role on this cruise?
I will participate in Leg 6, led by Dr. Gary Greene. I will be particularly interested in ROV dives in submarine canyons along the margins of the Gulf of California.

What are your primary goals?
We are interested in the processes by which submarine canyons form and
evolve. We have used the ROV to study canyon systems offshore California and Hawaii, and will now have an opportunity to study them in the Gulf of California. 

What do you expect to find?
Short answer: I don't know.

Long answer: The canyons offshore California have formed in an environment formerly dominated by compression and subduction, and currently dominated by strike slip faulting. The canyons offshore Hawaii have formed on active or recently active volcanic islands. The canyons in the Gulf of California have formed on a rifted margin. So, the tectonic environment of these canyons is substantially different from those we've already studied. Will this be reflected in major differences in canyon morphology and processes? That's what we want to know, and we can't predict the answers. 

What is your favorite/least favorite part of a research cruise?
Most favorite: finding something really new or unexpected.

Least favorite: being seasick. 

Why did you decide to become a scientist/engineer/etc? How did you become one? 
I wanted to always be working on new problems.

I always wanted to be a scientist, even before I knew what it meant. My undergraduate degree was in Physics, which is basic to many fields of science. As an undergraduate, I tried reading scientific journals in the library. I found the Geophysics journals both understandable and interesting. As a junior, I applied for summer internships at several institutions. I wound up spending the summer at the Lamont-Doherty Geological Observatory of Columbia University working on bathymetry and heat flow in small ocean basins. Liking the subject, I wound up applying to graduate schools to study Marine Geophysics. I went to the Scripps Institution of Oceanography rather than to Lamont, but five years later I went back to Lamont for my first real job. 

Alexandra Chee (top of page)

Dr. Michael S. Foster (top of page)
Moss Landing Marine Laboratories 

What are my primary goals?
To work with Dr. Gary Greene on studies of sediment transport in tropical canyons, especially carbonate sediments from rhodolith beds.

What do I expect to find?
Given the size and productivity of rhodolith beds in the Gulf, and likely transport by hurricanes, I expect considerable carbonate sediments at depth, especially downslope from large beds such as the one in Canal de San Lorenzo.

Favorite part of research cruises?
The opportunity for new discoveries and tests of hypotheses, and discussing science and life with colleagues.

Least favorite part of research cruises?
Really bad weather.

Why did I decide to become a scientist?
I became a scientist because I enjoy figuring out how nature works.

How did I become a scientist?
As far back as I can remember, I always liked figuring out how nature works and using scientific knowledge in theoretical and practical ways. So, one thing led to another.

Gary Greene (top of page)
MBARI Geologist





Rendy Keaten (top of page)
MBARI Research Technician  

What is your role on this cruise?
During the dives, I'll be doing one of several tasks in the control roomtaking notes in the dive log, updating the ArcView project with navigation information, taking video annotation, or operating the acoustic release for the benthic elevator.  

For each sample, the notes include: the type of sample (core, rock, push core, or sediment scoop), sample number, location the sample is placed onboard the ROV Tiburon (along with a small sketch if it's a rock), depth of the site, time code on the recording video, and GMT time. We do this so when the ROV comes onboard the ship, we can get each rock correlated with a sample number as we unload it. We also refer to the dive logs later to recall the sample information. 

As the samples are unloaded from the ROV, the wet lab gets very busy. The main focus is to get chemical composition of the water in mud samples. To do this, we have to get the mud samples processing so the pore fluids aren't contaminated by ambient water and atmosphere. We split the cores and put mud sections in pressure squeezers to collect the water. The water samples are then taken to the chemistry van to be analyzed onboard by Bill Ussler. 

After the rock samples come onboard, we wash, measure, and photograph them right away. When we do two dives in one day, this has to get done quickly so we have room to work with the next set of samples. We also cut rock slabs onboard for microscope thin sections and, as soon as, they dry we pack them to be shipped back to MBARI.   

What are your primary goals?
My primary goals are: to learn, for all the science equipment to work, to get all the samples we need, and to walk off the boat with a good idea of what the sulfate-methane boundary is like in the Gulf of California.  

What do you expect to find?
I expected basalts, some metamorphic rocks, faulting, deep basins, and mud—hopefully lots of mud. 

What is your favorite/least favorite part of a research cruise?
I hope to see the green flash this time, so I'll try to watch the sunset everyday. Seeing the topography of the ocean floor is always fascinating! My least favorite part is being away from my family, cats included, and green things.

Why did you decide to become a scientist/engineer/etc? How did you become one?
I came to geology by way of civil engineering. I was working with an engineering geologist and decided geology was much more interesting.


antoinepage.jpg (70207 bytes)Antoine Page (top of page)
Ph.D. Student
Portland State University

What is your role on this cruise?
I will help to subsample and process sulfide mineral chimneys for further microbiological analysis. 

What are your primary goals?
We want to understand how microorganisms distribute themselves in the high temperature sulfide chimneys over space and time, as well as the abiotic factors influencing this distribution (temperature, chemistry, and mineralogy). Along with my advisor, Anna-Louise Reysenbach, I will be responsible of identifying and quantifying the microorganisms in subsamples collected across various chimneys.     

What do you expect to find?
I hope to observe clear transitions in the composition and abundance of the microbial communities across the chimneys, and relate that to the data obtained by the other scientists involved in the project. All together, this study will help us to understand more about the constraints on microbial diversity and succession in high temperature deep-sea hydrothermal vent chimneys. 

What is your favorite/least favorite part of e research cruise?
My favorite part is definitely to get to see the environment in which the microorganisms I study live in.  

Why did you decide to become a scientist/engineer/etc?
My dad is a geologist, and I have always been interested in science. I like to understand more about biogeochemical systems and basically how things are related to each other in nature. And then of course you get to go in the field, to all these cool places you wouldn’t go to if you were not a scientist.   

How did you become one?
I received a B.Sc. in Biology and a M.Sc. in Oceanography at the University of Québec. Then I decided I wanted to move to another country and keep working on the deep-sea vents. Anna-Louise’s work was definitely a good incentive, and Portland appeared to be a city I would like to live in. 


Charlie Paull (top of page)
MBARI Senior Scientist  


Debra Stakes (top of page)
MBARI Geologist

What is your role on this cruise?
I am the chief scientist for the cruise. Much of my precruise responsibilities revolve around coordinating the tools and strategies for this highly ambitious effort. Many of the participating scientists bring years of submersible experience to this cruise. I want to be sure that we take advantage of all this accumulated wisdom in planning each dive. How much we accomplish will be determined by the quality of our precruise planning among ourselves and with the personnel in Operations who will make it happen. 

After the cruise, my role will change to that of a geochemist working on the mineralogy, petrology and chemistry of the sulfide chimneys that are collected. My specialty will be to collect information on both mineral chemistry and isotopic compositions of sulfur, oxygen and carbon. 

What are your primary goals?
My primary goals for this cruise are to successfully obtain complete carbonate-sulfide hydrothermal chimneys from the Guaymas hydrothermal site. We want the precipitates to enclose our instrumentation so that we can capture the thermal and chemical changes that accompany the formation of the chimney walls. The temperatures measured by the thermocouple array will then be compared to the predicted temperatures based on the mineral chemistry and the isotopic compositions. We will also look in the sediments and chimneys for evidence of microbiological precipitation of minerals using the scanning electron microscope. 

Of course the most primary goal is for the entire scientific party to be successful. This means also collecting sediments and fluids for different but comparative studies. 

What do you expect to find?
There have been several submersible studies to this area before so we have some idea of what scene will greet us on the first dive. We expect to find pagoda-like structures of carbonate-sulfides towering 7-9 meters above a flat sedimented floor. The ledges and summit of the pagodas should be large enough for the ROV to sit on top. There will be jets of black hydrothermal fluid exiting from the sides and top also, so we will need to be careful where we decide to stop. The sediments in this area are very unusual in that they are covered with thick bacterial mats and hydrocarbons. 

What is your favorite/least favorite part of a research cruise?
My answer to this question has not changed much in the past few years. My least favorite part of the cruise is the last few weeks of preparation (like now). There are so many details to fret over and so many questions to be answered. Having to send all of our equipment to Mexico makes the preparation a bit more complicated. 

My favorite part of the cruise is when we finally set sail. The planning is finally over and we can just focus on each dive and each job at hand. When you are at sea life becomes an intense but relatively uncomplicated routine of managing the science program, archiving the samples and planning each days work. 

And the most fun part is always celebrating your successes upon the return into port. 

Why did you decide to become a scientist/engineer/etc.?
I decided to become a scientist in grade school because I was fascinated with understanding the natural world and enamored with the thought of being an explorer. I clearly remember a movie shown in my fifth grade class that described "exploring the last frontier on earth" that convinced me to become an oceanographer. Since coming to MBARI I have also discovered that I enjoy the technical aspects of the field also. I may not have made a great engineer but I do like working on development projects to build new tools. 

How did you become one?
I became a scientist by staying in school until I had my doctorate degree. No one could distract me from my goals. I think that sometimes it takes being very determined. I took summer jobs working in research labs to hone my basic skills. I worked for an organic geochemist and a paleomagnetist at Rice University where I was an undergraduate. I also worked part-time for two years at the Johnson Space Center in Houston. This included very interesting jobs like exposing plant cultures to lunar material to see what would happen. 

Margaret K. (Meg) Tivey (top of page)
Woods Hole Oceanographic Institution

Associate Scientist, Dept. of Marine Chemistry and Geochemistry 

What is your role on this cruise?
I'm a co-Principal Investigator along with Debra Stakes, Geoff Wheat, Randy Koski, Anna-Louise Reysenbach, Jeff Seewald and Al Bradley. We're all working together on a collaborative project (funding for me, JS, AB, and ALR is through the National Science Foundation) to examine microbial colonization as functions of temperature, chemistry, and time in Guaymas Basin. We'll be using Tiburon and Jeff Seewald's isobaric fluid samplers to sample vent fluids, and we'll be deploying thermocouple arrays, designed and built by Al Bradley and colleagues, at the same vents. My focus of this program is on the thermocouple arrays: using temperature to determine how chimneys grow and change over time, and relating data from any chimney material that grows within the array, and that we can recover, to the temperature record. 

What are your primary goals?
The purpose of our study is to investigate the interaction of microorganisms with their geochemical environment, specifically to: 1) Trace the evolution of the thermal/chemical/physical environment within newly formed chimney walls over time-scales of minutes to months, and determine the distribution of microorganisms within this temporal/chemical/thermal/spatial framework; and 2) Assess subsurface geochemical processes responsible for the delivery of organic and inorganic metabolic energy sources and nutrients from deep-seated reaction zones to near seafloor environments.  

These goals will be attained by identifying microbial populations that inhabit well-constrained temperature and compositional domains within the walls of newly formed and existing chimneys. Temperature within the walls of newly formed chimneys will be monitored using thermocouple arrays that are enveloped during chimney growth. The new chimneys will subsequently be recovered and the solid material in the immediate vicinity of each thermocouple used for enrichment cultures, molecular phylogenetic approaches, and fluorescent in situ hybridization with 16S rRNA-specific probes, while splits of the same material will be fully characterized with respect to their mineralogic, chemical, and isotopic composition.  

My focus is on looking at the temperature records, and, working with Debra and Randy, characterizing the mineralogic, chemical, and isotopic composition of the chimney material. Vent fluids delivering nutrients and chemical energy from deep-seated subsurface reaction zones to the seafloor will be analyzed using a comprehensive analytical plan that involves quantitative determination of the abundance of aqueous organic, inorganic, and gaseous species.  

What do you expect to find?
We hope to characterize the conditions under which microorganisms live within these chimneys. We expect to have new chimneys grow through our thermocouple arrays, and are hoping that, when we recover the arrays after a few days time, that we'll be able to bring back some very young chimney material. There is a chance, however, that the chimney material will be so fragile that it will crumble and disintegrate as we recover the arrays. In that case we will still have excellent records of HOW the chimneys grow, but we'll miss recovering the actual material. Our fallback plan if that happens is to recover young chimneys after measuring the temperatures on their inner and outer surfaces, and use these chimneys for microbial, geochemical, and mineralogical studies. For example, we can then look for good fluid inclusions in minerals of the chimney wall and use those to collect data on the temperatures that were present when the chimney was forming.  

What is your favorite/least favorite part of a research cruise?
My least favorite part is during the planning stages: trying to get all of the equipment ready, making sure we have everything we need, anticipating possible problems and making sure we have contingency plans made. It is especially difficult on a cruise like this where we are building and using many new instruments.  

The fluid samplers have been modified, the thermocouple arrays are a new design, and the inductively coupled link is being used on every dive and needs to work on every dive or else we cannot communicate with the instruments. We'll also be working in a complex environment. It would be hard enough to plan if we knew exactly what the vent orifices looked like where we plan to put equipment. Instead, we have to try to be flexible so that the instruments could sit in a number of places.  

My favorite part is during the cruise. Once you're out there on the ship, you just work with what you have. If all your plans fall apart, then you wing it. Everyone works together to get the best product possible with what we have.  

Why did you decide to become a scientist/engineer/etc.?
A series of flukes: I went to college adamant NOT to be a scientist/engineer (my dad was one). But after not taking any science my first quarter, I really missed it. But the only course I could take (since I was now out of sequence with everything else) was Geology. Five field trips later, I was hooked. I decided it would be pretty nice to be able to make a living doing what I liked to do in my spare time anyway (camping, hiking, rock/fossil hunting).  

How did you become one?
I studied Geology in college, and then decided to see how I liked working in that field. After a year and a half as a technician working at the USGS (going to sea - again a fluke - the first job available was in the Marine Branch so I took it, and found out I loved going to sea!) I decided that my boss had the fun job - getting to figure out the puzzle based on data that I supplied him with. So it was time to go back to school for my PhD. After my PhD I applied and got a post-doc fellowship at WHOI, and then applied for a job on the scientific staff. I've been here ever since.    

Bill Ussler (top of page)
MBARI Senior Research Specialist



What is your role on this cruise?

My primary responsibility is the operation of our portable chemistry lab van. This 16-foot-long custom-built container contains a complete analytical laboratory for the analysis of the fluids and gases contained in marine sediments. There are 3 gas chromatographs configured to analyze methane and the low-molecular hydrocarbon gases ethane, propane, butane, and pentane, dissolved carbon dioxide, and dissolved hydrogen sulfide. Two ion chromatographs comprise a system to analyze dissolved cations (sodium, calcium, magnesium, potassium, strontium, and ammonium) and anions (chloride, bromide, and sulfate) in sea water and pore waters extracted from sediment cores. I will also collect and analyze large volume water samples for the concentration of radium and radon isotopes which can be used to trace fluid circulation through seafloor sediments.


What are your primary goals?

My main focus on this expedition is determining the chemistry of fluids and gases contained in surface sediments and ocean waters within and adjacent to the Guaymas Basin.


What do you expect to find?

Because the seafloor of the Guaymas Basin is a methane-rich environment, our studies will focus on the geochemistry and microbiology of methane production and its anaerobic consumption. There are large temperature differences across the basin seafloor, and we expect to see comparable spatial differences in the amounts of methane, dissolved inorganic carbon, sulfate, and hydrogen sulfide, and in their stable isotopic values, coupled with changes in the composition of sub-seafloor microbial communities.


What is your favorite/least favorite part of a research cruise?

My favorite part of any research cruise is the discovery of new and interesting facts about the ocean. My least favorite parts are finalizing all the important details necessary for packing the equipment and supplies; and feeling seasick while at sea.


Why did you decide to become a scientist/engineer/etc? How did you become one?

I have had a long-standing interest in the sciences since childhood, especially chemistry and geology. Becoming a scientist requires persistence, adaptability, inquisitiveness, and a willingness to learn and do many, often mundane, tasks. Tenacity combined with many years of formal education has allowed me to pursue a rewarding career in the Earth Sciences.


I have two suggestions for future ocean scientists: 1. obtain an undergraduate degree in one of the core sciences (chemistry, physics, or biology) in preparation for graduate work in the marine sciences; and 2. develop technical and engineering skills that can be applied to the development of new techniques and instrumentation. 


Jorge Ledesma Vazquez (top of page)