2010 SouthernExpedition

Day 6 – Diving on the seafloor mounds – finally!
July 14, 2010

1900 hours – On station at the Santa Monica mounds
Latitude 33 degrees 48.4203 minutes N
Longitude 118 degrees 39.7364 W

No matter how much planning goes into every detail of a research expedition, everyone involved has to remain flexible because the unplanned is bound to happen. Flexible was certainly the name of the game today.

After sailing overnight to the Santa Cruz Basin, where we planned to begin explorations on a mapped chemical munitions dump first thing this morning, we woke to strong winds that made it unsafe to launch the remotely operated vehicle. The choice was between staying in the area and waiting for the wind to die down—if it didn’t die the time would be wasted—or moving on to our next dive site, closer to shore and likely a bit calmer. An agonizing decision, as Chief Scientist Peter Brewer and several others on board were very interested in exploring what was at the Santa Cruz Basin site. But ship time is a precious commodity, so nobody wants to waste it. Brewer decided to move on to the Santa Monica Basin site, to study the pore-water chemistry with the laser Raman spectrometer.

Most of the morning was spent in transit, and the ROV Doc Ricketts was finally in the water just before lunch. The vehicle reached the bottom and we started a transit across a mound where MBARI geologist Charlie Paull and his group had previously discovered methane venting. All seemed well, until an alarm sounded on the ROV hydraulic pressure system. Chief Pilot Knute Brekke called for an immediate return to the surface and the ROV and ship’s crew gathered for a “dead vehicle recovery” in which the vehicle is brought up alongside the ship, then guided between the ship’s two hulls and is pulled in by its tether. Once safely aboard, the pilots checked the entire vehicle to find the source of the leak. In less than an hour, they narrowed it down to a failed O-ring on a pressure transducer, which they were able to replace and get the vehicle ready for another dive.

Peter Walz, where he spends a lot of time—in the moon pool installing and adjusting instruments on the ROV for the next dive, or removing them after the last dive.

So, at about 3:30, the vehicle was back in the water and dove to a depth of more than 800 meters for the first science effort of the day. Several Raman readings were taken on the outer flank of the mounds discovered by Charlie Paull, but there was no strong evidence of methane at these locations. Tomorrow we will focus our investigations with the pore-water probe at the crest of the mound where Paull reported active methane venting. We will also take traditional push core samples at the same locations where the Raman system detects methane, to compare the results between the two methods.

Zeng Zhigang, a visiting scientist from China, cleans off clams found in push core samples.

That’s the plan. We can only hope that this time the stars are aligned in our favor and we execute exactly what we have planned.

—Nancy Barr

Paull, C.K., W.R. Normark, W. Ussler III, D.W. Caress,and R. Keaten (2008). Association among active seafloor deformation, mound formation, and gas hydrate growth and accumulation with the seafloor of the Santa Monica Basin, offshore California. Marine Geology, 250: 258-275.

Xin Zhang and Andreas Hofmann process a push core mud sample, while Melissa Luna looks on.
After a long day, capped with the processing of muddy samples, the crew got a little punchy, and indulged in an impromptu "spa treatment". From left, Andreas Hofmann, Xin Xhang, and Melissa Luna.
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Leg 1

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 ROV Tiburon'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.


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.

CTD Rosette

A CTD rosette is a cylindrical frame holding a group of plastic water-sampling tubes. Attached to this frame are instruments for measuring water temperature and conductivity (salinity) at various depths. Also attached to the rosette are instruments for measuring parameters such as chlorophyll, nutrients, and particulate matter in the water. As the frame is lowered over the side of a ship, water samples are taken automatically at various depths. Then the frame is raised to the surface again.

 Research Team

Peter Brewer
Senior Scientist, MBARI

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, MBARI

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

Peter Walz
Senior Research Technician, MBARI

Peter has worked as a research technician for a variety of scientists at MBARI. Most recently he has supported the research efforts of Dr. Peter Brewer and his interests in the ocean chemistry of greenhouse gases such as methane and carbon dioxide. Peter assists with the design, testing and deployment of the ocean going science hardware and works closely with the marine operations group to integrate new equipment to work with MBARI's ROV's.

Andreas Hofmann
Postdoctoral Fellow, MBARI

Andreas is a MBARI Postdoctoral Fellow in the Brewer lab. He obtained a PhD in marine biogeochemistry in the Netherlands after his biology undergraduate and bioinformatics graduate studies in Germany. Andreas' specialty is pelagic and benthic biogeochemical modeling with a focus on pH and proton cycling. At MBARI, Andreas is working on the relation between pH and soundspeed, the characterization of marine "dead zones", the development of a sediment model to estimate biogeochemical rates from pore-water methane profiles obtained with the group's deep sea sediment Raman Probe, and on a few other related topics. On this cruise, Andreas will be involved in experiments using the mid-water CO2 and O2 control system and the sediment Raman probe, as well as in various data processing tasks.

Melissa Luna
Summer Intern, MBARI

Melissa is an MBARI 2010 Summer Intern working in the Brewer lab. She is a graduate of College of Charleston in Charleston, South Carolina with a BS in Chemistry. This summer Melissa will be working on using laser Raman techniques to examine hydrogen sulfide and bisulfide signals as a function of pH in marine pore waters in sea floor sediments.

Nancy Barr
Web/Print Project Manager, MBARI

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. Nancy has been to sea with several MBARI research groups, helping them to carefully remove worms from whale bones, annotate video, sift seafloor sediment, and collect and process water samples. 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.

Xin Zhang
Seafloor Hydrothermal Activity Laboratory
Key Lab of Marine Geology and Environment
Institute of Oceanology, Chinese Academy of Sciences

Xin Zhang is a former MBARI student of Peter Brewer and Bill Kirkwood. He was involved in the development of a Deep-Sea Raman Probe for the measurement of sediment pore-water geochemistry.

Zeng Zhigang
Director, Seafloor Hydrothermal Activity Laboratory
Key Laboratory of Marine Geology and Environment
Institute of Oceanology, Chinese Academy of Sciences

Zeng Zhigang's research interests are in hydrothermal vents, geochemistry, economic geology, and the exploration of geology and mineral resources. He is on this expedition to learn more about MBARI's tools and methods for study ocean chemistry.