Monterey Bay Aquarium Research Institute

Deep-Sea Chemistry Logbook
Day 6: Fascinating territory

March 19, 2012

Today’s dive covered a wide diversity of terrain and sea life. Left, brisingid seastars cling to a cliff, and right, an aggregation of gastropods (snails).

Today, the science team covered a lot of fascinating territory at a fracture zone, where two tectonic plates meet—the Pacific Plate is slowly sliding north relative to the North American Plate. Large boulders, rubble, cliffs, a variety of animals; if the same territory was on dry land, it would be as beautiful as a national park.

When the Peter Brewer and Charlie Paull lab teams visited this same area in 2003, they found one active methane gas vent. Today, after locating the pink marker they left behind at the site, we found several such vents, with steady streams of bubbles rising from the seafloor and easily seen on sonar 400 meters (1,312 feet) above the seafloor. Those vents were sure to provide a chemical signal, but they could also freeze into a solid hydrate and block the intake of the laser Raman system, so we went exploring for other signs of chemical activity in the area rather than stop to take any measurements right away.

The Raman pore-water probe was inserted into the middle of a bacteria mat. No sign of methane. Then it was inserted into a dense field of vesicomyid clams, which are known to live at seafloor vents. No sign of methane. What was going on? It could have been because the sticky clay just beneath the surface forced the methane into a thin layer which was then consumed by the bacteria and clams.

For the first time, the team had a new map of the area prepared just two days ago by the MBARI AUV mapping team; the map was used as the basis for exploration. Unusual looking mounds and pits seen on the maps were explored and found to be amazing fields of huge calcium carbonate boulders and slabs.

By mid-afternoon, knowing the day’s dive would soon end, we returned to the bubbling vent and inserted the Raman probe. Finally, a strong methane signal was detected. The tip was inserted step by step into the sediment, until the methane started turning into hydrate—an ice-like cage that forms around the gas when exposed to the cold seawater at depth—and clogged up the line. That marked the end of pore-water measurements for the day. The line would clear when the equipment came up to the warmer water with less pressure, but we didn’t have time to bring the vehicle up to clear the line and go back down again.

The final step at the site of the gas vent involved scraping away some of the sediments with the “benthic hoe.” As soon as the mud was disturbed, pieces of solid methane hydrate were released and started rising up. As the methane gas traveled through the sediment it created a sort of chimney, which then became lined with the solid hydrate.

Peter Brewer said he considers himself lucky to have the support of his two key assistants, Research Specialist Ed Peltzer and Research Technician Peter Walz. “They are super guys,” Brewer said. “They did a great job today.”

Other MBARI employees are also unsung heroes in the success of this ocean chemistry expedition. These are the people who design and fabricate the tools we take to sea. Machine Shop Supervisor Ray Thompson figured out how to drill a tiny hole (2.03 millimeters, or .080 of an inch) down the center of the 1.27 centimeter (half-inch) diameter titanium probe, then did the masterful machining of the various threaded pieces. The new titanium tip is 55 centimeters (21.6 inches)—the old one was 30 centimeters (12 inches)—allowing us to sample fluids deeper in the sediments, and is strong enough to penetrate through carbonates. Mechanical Engineer Farley Shane designed the tripod and Mechanical Technician Frank Flores welded it. This tripod has allowed much more precise control and insertion of the pore-water probe. None of these MBARI staff members typically come out to sea to witness their work in action, but they are definitely much appreciated by the science team.

A few of the other sights found at a depth of about 1,570 meters (5,150 feet) in the Gulf of California. Clockwise from top left: tube worms, a benthoctopus putting on a little dance for the science visitors, carbonate mounds, and large rock formations.

—Nancy Barr

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Deep-Sea Chemistry

R/V Western Flyer

The R/V Western Flyer is a small water-plane area twin hull (SWATH) oceanographic research vessel measuring 35.6 meters long and 16.2 meters wide. It was designed and constructed for MBARI to serve as the support vessel for ROV operations. Her missions include the Monterey Bay as well as extended cruises to Hawaii, Gulf of California and the Pacific Northwest.

ROV Doc Ricketts

ROV Doc Ricketts is MBARI's next generation ROV. The system breaks new ground in providing an integrated unmanned submersible research platform, with many powerful features providing efficient, reliable and precise sampling and data collection in a wide range of missions.

Laser Raman spectrometer DORISS2

By bouncing a specially tuned laser beam off of almost any object or substance—solid, liquid, or gas—a laser Raman spectrometer can provide information about that object's chemical composition and molecular structure.

Push cores

A push-core looks like a clear plastic tube with a rubber handle on one end. Just as its name implies, the push core is pushed down into loose sediment using the ROV's manipulator arm. As the sediment fills up the core, water exits out the top through one-way valves. When the core is pulled up again, these valves close, which (most of the time) keeps the sediment from sliding out of the core tube. When we bring these cores back to the surface, we typically look for living animals and organic material in the sediments.

CTD Rosette

The CTD measures conductivity (which helps determine salinity), temperature, and density (which helps determine depth). This particular CTD runs profiles of the water column (surface to bottom) and along the way, collects discrete water samples (at specific predetermined depths) using the rosette of niskin bottles. Each bottle can collect a water sample. The transmissometer measures the number of particles in the water and the oxygen sensors tell us how much dissolved oxygen is present. Both of these instruments go onto the CTD rosette and give us a profile of the water column.


Vibracoring is a common technique used to obtain samples from water-saturated sediment. These corers work by attaching a motor that induces high frequency vibrations in the core liner that in turn liquefies the sediment directly around the core cutter, enabling it to pass through the sediment with little resistance.

Heat-flow probe

MBARI's heat-flow probe is mounted on the side of the ROV Doc Ricketts inside the vertical stainless steel box. This both protects the delicate probe and provide the track so that the probe can be inserted into the sediment along a totally straight path.  The probe contains five high precision platinum sensors which are used to measure the vertical temperature gradient in the sediments. This gradient along with some knowledge of the heat capacity of the sediment allows scientists to calculate the rate of heat loss from the sediments into the ocean.


R/V Western Flyer

Ian Young


Andrew McKee
First Mate


Matt Noyes
Chief Engineer


Cole Davis
Second Mate


Lance Wardle
First Engineer


Shaun Summer
Relief First Engineer


Olin Jordan


Craig Heihn
Relief Deckhand


Jason Jordan
Relief Deckhand


Dan Chamberlain
Electronics Officer


Patrick Mitts


ROV Doc Ricketts

Knute Brekke
Chief ROV Pilot


Mark Talkovic
Senior ROV Pilot


Randy Prickett
Senior ROV Pilot


Bryan Schaefer
ROV Pilot/Technician


Eric Martin
ROV Pilot/Technician


 Research Team

Peter Brewer
Chief Scientist

Peter has taken part in more than 30 deep-sea cruises, and has served as chief scientist on major expeditions and on more than 90 ROV dives with MBARI ships and vehicles. His research interests include the ocean geochemistry of the greenhouse gases. He has devised novel techniques both for measurement and for extracting the oceanic signatures of global change. At MBARI his current interests include the geochemistry of gas hydrates, and the evolution of the oceanic fossil fuel CO2 signal. He has developed novel techniques for deep ocean laser Raman spectroscopy, and for testing the principles and impacts of deep ocean CO2 injection.

Ed Peltzer
Senior Research Specialist

Ed is an ocean chemist who has been with MBARI since 1997. He has been involved in developing in situ laser Raman spectrometry instruments and lab based analytical techniques to study the composition of gases in gas hydrates and deep-sea vents. He has collaborated on the development of new instrumentation for the measurement of temperature and pH from ROVs and deep-sea observatories. As the group's project manager, Ed is also responsible for expedition planning and logistics.

Nancy Barr
Web/Print Project Manager

Nancy manages the editing, design, and production of the MBARI annual report and participates in a variety of editorial and communication projects. She also oversees the institute website. For this expedition she will be in charge of the daily reports that will be posted to this website and will assist with other science crew tasks.

Peter Walz
Senior Research Technician

Peter has worked as a research technician for several scientists at MBARI. For the past 10 years he has supported the research efforts of Peter Brewer and his interests regarding the ocean chemistry of greenhouse gases such as methane and carbon dioxide. Peter is responsible for the design, testing, maintenance, and deployment of the oceangoing science hardware and works closely with the marine operations group to integrate new equipment and technology with MBARI's ROVs.

Martín Hernández Ayón
Universidad Autónoma de Baja California

Martín Hernández Ayón is a chemical oceanographer. His research is focused on the inorganic carbon system, ocean acidification and biogeochemistry in the coastal regions of Baja California, the Sea of Cortez, the subtropical region where the oxygen minimum zone is located, and, more recently, the Gulf of Mexico.

Gabriela Y. Cervantes
Graduate Student
Universidad Autónoma de Baja California

Gaby is a graduate student in the coastal oceanography program at the University of Baja California in Ensenada, Mexico. She is doing her graduate studies on the dynamics of CO2 in seawater from a coastal monitoring site known as Ensenada Station.

Abbey Chrystal
Graduate Student
University of California, Santa Cruz

Abbey Chrystal is a graduate student in earth and planetary sciences at the University of California, Santa Cruz. Her research focuses on reconstructing long-term records of past ocean carbonate chemistry parameters. On this cruise she will be collecting sediment push cores and bottom water samples to help calibrate the relationship between the shell chemistry of benthic foraminifera and the chemistry of the bottom water and porewater chemistry in which they grow.

Joseph Murray
Graduate Student
University of California, Santa Cruz

Joseph Murray is a first year ocean sciences Ph.D. student in the lab of Dr. Adina Paytan at the University of California, Santa Cruz. He is interested in coastal marine chemistry and the impact of submarine groundwater discharge on marine biogeochemical cycles. His current research is focused on using oxygen and nitrogen isotopes in nitrate to study sources and cycling of nitrogen in the coastal ocean. As part of this cruise, he plans to collect samples in order to study the impact of anthropogenic fertilizer runoff from the Yaqui Valley on the marine nitrogen cycle in the Gulf of California, including assessing the role groundwater discharge plays in this process.

Last updated: Mar. 21, 2012