Monterey Bay Aquarium Research Institute
2010 SouthernExpedition


Day 10 – Explorers armed with a titanium probe
July 18, 2010

1800 hours – Southwest Santa Monica mounds
Latitude 33 degrees 47.3453 minutes N
Longitude 118 degrees 40.0028 W

Sometimes you find something where you least expect it. When MBARI geologist Charlie Paull originally mapped this area with the mapping autonomous underwater vehicle, he found two seafloor mounds formed by the accumulation of pure gas hydrates. Charlie suggested that one mound would be the more active and interesting, so that is where we have conducted our experiments for the last few days. Today we planned a short dive on the other mound, which we expected to be less active and therefore fairly lifeless and of minimal interest.

When we got to this mound—smaller and deeper than the other one—we found large fields of orange and white bacterial mats, enormous stretches of deep, fluffy, flocculent bacteria covering big stretches, sitting on a layer of sediment was as soft and jiggly as Jell-O.

Aside from the mapping done by Charlie Paull and the MBARI AUV group, we believe this mound has never been explored before. And since mapping is done with sonar, and not a visual survey of the area, we were exploring new territory with the ROV, our video camera, and our every-trusty titanium laser Raman pore-water probe. Peter Brewer found the site so interesting he decided to seize the moment and continue surveying this mound for the entire day, rather than pick up and move back to the other mound as had been planned. This site is in the shipping lane for the ports of Los Angeles and Long Beach and so Captain Ian Young requested help from the port authority in advising vessels to give us clearance by a kilometer. It worked beautifully and an unusual site could be visited.

These are some of the fantastic scenes from diving on the Southwest Santa Monica Mound today. Orange and white bacterial mats covered the methane-rich area. In some of the pictures the ROV robotic arm is inserting the laser Raman pore-water probe into the sediment.

The ROV traversed the crest of the mound at about 858 meters depth and along its flanks. The mound rises about 20 meters above the surrounding seafloor. An area approximately 70 meters by 50 meters was explored during the course of the day. Oxygen concentrations in the water were extremely low, yet bacterial life is thriving here. Unlike the shallower mound, we did not see the expansive fields of clams, just acres of snow white and orange fluff.

Directly in front of the chief scientist’s chair in the ROV control room aboard the Western Flyer are two large monitors—the bottom one shows the video from the main camera and top one shows real-time data from the laser Raman spectrometer which tells which gases are present in each sample.

The pilots inserted the pore-water probe some 38 times, sometimes finding they could penetrate only about 10 or 15 centimeters before hitting a hard layer. Brewer became more bold with this new tool as the 10-hour dive progressed, telling the pilots to push it down as far as they could in order to get readings from as deep as possible. But when pushing down on the probe was enough to lift the ROV off the seafloor, we knew it was time to stop! And when a site returned a significant reading of methane, then a push core was taken at the same place so that the Raman data can be compared with the data gathered from the push cores.

The day wrapped up with the science crew processing the mud from the push cores, extracting the pore waters which will be sampled later. Perhaps this dirty, smelly, time-consuming task will soon be a thing of the past, now that such data can be collected in situ in real time. That would be a perfect outcome from the work of this expedition.

—Nancy Barr

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Leg 1
 Equipment

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.

Vibracores

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.