Monterey Bay Aquarium Research Institute

2012 Climate and Deep-sea Communities Expedition

 

Day 5: In situ experiments in the deep ocean
November 16, 2012

The first scientific observations of deep-sea animals occurred during the Challenger expeditions, which began in 1872, when trawls of the midwater and deep seafloor brought up animals unlike those observed in shallower water. Since then, studies of deep-sea animals involved recovering them from trawls or collecting those that washed up on beaches, but the samples were often damaged or dead. It has only been in the last several decades that remotely operated vehicles have provided a window for in situ observations of these animals, plus the ability to test hypotheses. Henry Ruhl and Amanda Kahn are conducting in situ measurements and experiments with Ken Smith's lab using the ROV Doc Ricketts as their eyes and hands underwater.

remotely operated vehicle
ROV Doc Ricketts was deployed from the moon pool in the center of the Western Flyer. It then descended 4,000 meters to the seafloor, acting as eyes and hands underwater for scientists. Photo: Amanda Kahn

Henry Ruhl is studying the link between surface climate and deep-sea populations, with a focus on the function of the deep ocean as a carbon sink. He deployed respiration chambers that measure oxygen drawdown caused by a sea cucumber inside the chamber, a useful proxy for studying the amount of organic carbon (food supply) used by the animals he studies. During the two ROV dives, different species of sea cucumbers were put in the chambers so their respiration could be measured. These measurements would be impossible to do at the surface unless brought up in a pressurized tank—a sea cucumber could not survive the pressure and temperature changes associated with an ascent from such depths.

Respiration chambers seal in an animal in a given volume of seawater and measure the oxygen consumed over a certain period of time. Such measurements allow calculations of the amount of food used by the animal. 

In addition to servicing the respiration chambers, the pilots of the ROV Doc Ricketts carefully recovered the chambers used to dye sponges for growth studies, collected more push cores of deep-sea sediments, and collected animals from Station M. Although it is one of the best-studied deep-sea areas in the world, one study conducted there found 17% of species collected to be new to science, so the potential for great discoveries remains.

A diversity of sea cucumbers was collected during the dive. Some appear slightly different than known species, so all will be carefully studied to see whether any are new species. Photo: Carola Buchner.

At the same time the in situ experiments were occurring, the others busied themselves in turning around the sediment trap/camera tripod setup and the sediment event sensor (SES).  Long deployments require careful diagnostics and maintenance to go on when they do come to the surface, so turning those two moorings around has occupied the whole day. Two instruments remain on deck to be redeployed: the SES and the camera tripod setup. Likewise, two instruments have yet to be recovered from the seafloor: the free vehicle grab respirometer (FVGR) and the elevator with Henry Ruhl’s respiration chambers. All of these activities will occur beginning tomorrow at first light and will be conducted as quickly as possible: weather conditions have begun to deteriorate with noticeably larger waves and wind.

Alana Sherman and Paul McGill check components of the camera tripod to ensure it is ready for deployment tomorrow.  Photo: Carola Buchner

—Amanda Kahn

Previous log Next log

 Logbook

Day 5
November 16, 2012
Experiments in the deep ocean

Day 4
November 15, 2012
Recovering long-term sampling equipment

Day 3
November 14, 2012
Rover recovery and recharge

Day 2
November 13, 2012
Helping hands for free vehicles

Day 1
November 12, 2012
No idle hands

 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, the 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.

Long-term sediment trap

Sequencing conical sediment traps, each with an effective mouth opening of 0.25 m2, are moored at 600 meters and 50 meters above the bottom at 3,500- and 4,050-meter depths, respectively. Trap sequencers are programmed to collect sinking particulate matter in sampling cups every 10 days. In the laboratory, the collected particulate matter is analyzed in duplicate for total and inorganic carbon.

Push cores

A push-core is 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 the cores are brought back to the surface, scientists typically look for living animals and organic material in the sediments.

Benthic Rover

The Benthic Rover is a mobile physiology lab. In a series of experiments, the rover measures how much oxygen seafloor animals are using. Precise motors lower two 30-centimeter-wide (12-inch) sample chambers into the sediment, where probes record oxygen levels. Two acoustic scanners use ultrasound (in 4-MHz pulses) to look 10 centimeters (four inches) deep into the sediment for large animals, such as worms.

High-frequency suction samplers

This midwater toolsled contains a High-Frequency Suction Sampler (HFSS). You can see one of the 12 collection buckets in this image. This sampler acts like a vacuum cleaner sucking up samples and depositing them into one of the 12 buckets.

Benthic elevator

The benthic elevator allows us to carry more than the ROV itself can carry. Loaded with sediment enrichers, it is deployed from the ship before the dive and free-falls to the bottom where the ROV pulls the equipment from the elevator for use. After the ROV is recovered, the elevator anchor's acoustic release is triggered from the ship, and the elevator freely ascends to the surface and is recovered.

Free vehicle grab respirometer (FVGR)

Oxygen consumption (a measure of biological activity) of the organisms living in the sediment is measured using a free vehicle grab respirometer (FVGR) which retrieves sediments for faunal examination and chemical analyses.

Lagrangian Sediment Trap (LST)

The Lagrangian Sediment Traps or LSTs are used to collect sinking material at specific depths. Once they are deployed they will sink to a programmed depth and float along with the current. After a few days the sample cups will close and the LST will activate its variable ballast system to rise to the surface to be recovered.

Camera mooring

The time-lapse camera consists of a Benthos 377 camera mounted on a titanium frame at an angle of 31 degrees from horizontal with the lens approximately two meters above the seafloor. The camera is equipped with a 28-millimeter Nikonos lens, providing angular coverage of 50 degrees in the horizontal and 35 degrees in the vertical plane, and holds 400 feet of 35-millimeter color-negative film. Up to 3,500 images can be collected in 4.6 months. Two strobe lights, one mounted on either side of the camera housing, illuminate approximately 20 square meters of the seafloor beginning at a distance of 1.8 meters from the camera frame and extending approximately 6.5 meters from the base of the camera frame. In June 2007 a high-resolution digital camera was added to the frame.
 Research Team

Ken SmithKen Smith
Senior Scientist, MBARI

Ken is an open-ocean ecologist with 40 of years experience going to sea and studying extreme ecosystems ranging from the deep ocean to Antarctic icebergs. The main thrust of his research is to understand the impact of a changing climate on deep-sea and polar ecosystems. On this cruise, he will coordinate the deployments of autonomous instruments to continue long time-series studies at Station M on the Monterey Deep-Sea Fan at 4,000 meters depth.

Alana Sherman Alana Sherman
Electrical Engineer, MBARI

Alana specializes in instrumentation. On this cruise she will be deploying three instruments: the Benthic Rover, the time-lapse camera tripod, and Lagrangian sediment traps.

jake ellena Jacob Ellena
Research Technician, MBARI

As lab technician, Jake's responsibility is to make sure everything runs smoothly so samples can be collected at sea and analyzed in the laboratory. He'll organize much of the equipment being taken to sea, and will ensure everything works during the cruise. Once ashore he'll take all the samples and analyze them in a variety of ways with the goal of achieving a better understanding of how the ocean works.

John FerreiraJohn Ferreira
Mechanical Engineering Technician, MBARI

John will help with all the mechanical maintenance and repair of the Benthic Rover, the sediment traps, and the seafloor camera tripod.

rich henthorn Rich Henthorn
Software Engineer, MBARI

Rich has been at MBARI since 2000 working on many types of projects, but mostly writing software for MBARI's autonomous vehicles. On this cruise Rich is responsible for the control system on the Benthic Rover. The Rover will be retrieved from the seafloor and then redeployed for six more months.

Crissy HuffardCrissy Huffard
Senior Research Technician, MBARI

Crissy completed a post-doc in MBARI’s Midwater Ecology lab, after which she worked for Conservation International Indonesia supporting marine protected area monitoring efforts. She has just returned to MBARI, as a senior research technician in Ken Smith’s lab, and on this cruise is learning about the lab’s shipboard operations and instruments.

Paul McGill Paul McGill
Electrical Engineer, MBARI

Paul specializes in underwater vehicles and instrumentation. On this cruise he'll help prepare, deploy, and recover the drifters, crawlers, and landers being used to study the deep ocean at Station M.

Henry Ruhl Henry Ruhl
Head, DEEPSEAS Group
National Oceanography Centre, Southampton

Researching the links between climate variation and deep-sea ecology has been a primary focus for Henry. In particular he's interested in understanding how changes in climate are related to the role of the deep ocean as a carbon sink. During the cruise he will be researching the abundance and distribution of animals on the seafloor, as well as their respiration rates using specialized chamber systems. Respiration is a good indicator of carbon utilization and provides key input into estimates of carbon flow and the importance of biodiversity at the seafloor.

Amanda Kahn Amanda Kahn
Graduate Student
University of Alberta

Amanda studied plate sponges at Station M as an intern in the Smith lab. She is now pursuing a Ph.D. at the University of Alberta, studying the growth, energetics, and impacts of hexactinellid sponges that form reefs in the straits of western Canada. Her interests outside of research include scuba diving, martial arts, and science blogging.

Carola Buchner Carola Buchner
Engineer of Biotechnology

Carola has worked for many years in the field of microscopy and volunteered on one of Ken Smith´s Sargasso Sea expeditions earlier in 2012. On this trip she will help in the lab. Her interests outside the work are photography and scuba diving.