Monterey Bay Aquarium Research Institute

Deep-Sea Chemistry Logbook
Day 7: Between a rock and a hard place

March 20, 2012

While this week’s news reports are filled with stories about James Cameron heading to the bottom of the Mariana Trench, the deepest spot in the ocean, we at MBARI continue with our day-in, day-out study of the deep sea. When you spend a lot of time watching the images coming back from the cameras on the remotely operated vehicle (ROV), you can sometimes lose sight of just how amazing this all is. Most of us on the ship have done this before, many have been going to sea or working with seafloor video for decades. But we are aware that we are often visiting places nobody has ever seen before, such as most of the locations we visited on this cruise.

Based on maps, both older, low-resolution maps and the new, amazing, high-resolution maps produced by MBARI’s own autonomous underwater vehicle, ocean chemist Peter Brewer and marine geologist Charlie Paull picked out the sites where fluid venting was most likely. That’s why we have been searching on spreading seafloor valleys—spots where tectonic plates are slipping—and on mounds, slumps, and seamounts. They all look promising when looking at bathymetry, but until we take the cameras and instruments down there, we are never sure.

sonar image
Maps help identify possible locations of gas venting, then while exploring, the ROV sonar often helps locate the vents. In this sonar image from yesterday, the two blue streaks at the bottom indicate there were two vents behind the vehicle.

One seamount and one slump at the edge of the continental margin attracted our attention today. Like yesterday, some of the terrain kept us riveted to the video monitors. But unlike yesterday, there were no signs of gas venting; no bubbles rising up from the seafloor. The two sites were 16 kilometers (10 miles) apart, necessitating the recovery of the ROV between the two sites and a second dive. What we found were pillow basalt from a long-ago volcano, rubble fields of volcanic rock, and steep cliffs as high as 140 meters (460 feet). We found a large collection of egg cases (probably from sharks), sponges, sea stars, octopus, and fish.

egg case image
The seamount we visited in the morning was littered with egg cases, probably from sharks. Unfortunately, we did not see any sharks on this dive.
lava images
Two frame grabs from the ROV video camera as we explored around a seamount covered in pillow lava and fields of basalt rubble.

We did stop and take some Raman measurements with the pore-water probe since we were down there anyway, but we did not see any significant chemical signal. On the bright side, the Brewer team was recognized today by a writer for the Society for Applied Spectroscopy. “Potentially one of the more important review articles we have published,” the society’s blogger wrote, regarding a just-published Brewer-team paper describing how it uses the laser Raman spectrometer in the deep sea to accurately measure methane and sulfur in pore water. Always nice to be recognized by one’s peers!

As you can see from the list of researchers on the right side of this page, we have two Mexican chemists with us on this cruise, Martín Hernández Ayón and Gabriela Cervantes.

From Martín Hernández Ayón: At the end of 2008, I received an email from Dr. Brewer inviting me to participate in the Gulf of California Expedition as a part of his team. But it wasn’t until May 2009 when I met Peter for the first time at MBARI during my visit to Francisco Chavez’s lab that we had the opportunity to talk about the topic and the concerns for this cruise. At the beginning of 2010 Peter and I both attended a meeting of the Intergovernmental Panel on Climate Change (IPCC) in Okinawa, Japan, and we had time for an update and to make plans for geochemistry studies using Raman spectroscopy with the ROV on the new gulf expedition. My interest in the gulf exploration was not only for the area, but also because MBARI is, in my opinion, an oceanic NASA, which has very advanced technology to explore the ocean and answer questions on issues such as hydrothermal and methane vents. This experience with Peter Brewer and his team is a unique opportunity for my undergraduate student Gabriela and me, because we are able to witness what we learn only in books, scientific papers, or films. We recognize the efforts of MBARI for their mission, and we also are very pleased to open the door on collaborations with researchers and students from other countries.

Martin and Gaby
Gabriela Cervantes and Martín Hernández Ayón with one of the push-core sediment samplers they took off the remotely operated vehicle. The two have had a few such mud samples to process every night; they carefully separate out sections of the core for later testing for trace metals.

—Nancy Barr

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Deep-Sea Chemistry
 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 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.

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.

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.

 Crew

R/V Western Flyer

Ian Young
Master


 

Andrew McKee
First Mate


 

Matt Noyes
Chief Engineer


 

Cole Davis
Second Mate


 

Lance Wardle
First Engineer


 

Shaun Summer
Relief First Engineer


 

Olin Jordan
Oiler


 

Craig Heihn
Relief Deckhand


 

Jason Jordan
Relief Deckhand


 

Dan Chamberlain
Electronics Officer


 

Patrick Mitts
Steward


 

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
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 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
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. 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
MBARI

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
Collaborator
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. 22, 2012