This remarkable instrument enables researchers to gather more data by providing an additional platform for equipment and samples. The "benthic elevator" utilizes a combination of glass-sphere floats for buoyancy in ascents, and a drop-weight that could be released acoustically, or by an ROV, for initiating descents. The "elevator" is released from the ship to the ocean floor with the drop-weight hanging far enough below the structure to hit bottom first and allow the floated portion of the elevator above to decelerate before impacting the bottom. The cargo bay of the benthic elevator can carry equipment down to an ROV for deployment, or it can be used to transport samples up to the surface following release of the drop-weight for a free ascent. This arrangement would accommodate larger science packages than currently can be handled solely by the ROV. It would also allow a much greater sampling capacity per dive, since the ROV could load samples into the elevator for transport to the surface in addition to loading its sample drawers. See Leg 2 precruise efforts for additional information about a benthic elevator constructed specifically for their research.
The bubble box is used for watching the rise of bubbles of gas (methane) or liquid CO2 without the lateral effects of eddies or near-ROV turbulence. It also provides a clutter-free background and a scale for measuring the size of the droplets/bubbles.
At right, a
The clathrate bucket is used for recovering push cores containing either gassy sediments (sediments with trapped gas) or methane clathrate hydrates at in situ temperature and pressures—so we get the samples back without decomposing the clathrate hydrates.
Left: Clathrate bucket and gas sampler on ROV Tiburon's front porch prior to a dive at Hydrate Ridge.
Middle: Close up of the clathrate bucket and gas sampler.
Right: In full operation, a sample is inserted into the clathrate bucket at Hydrate Ridge.
A core catcher is
a collection of spring steel fingers that form a spiral pointing inward.
These fingers are mounted on a steel ring that is attached to the bottom
end of a core tube. During core collection, the fingers allow the sediment
to pass up into the core tube, but spring back into place to prevent the
core material from falling out during core handling. Core catchers work
best with fine-grained, clay-rich sediments, whereas loose, sandy
sediments are more difficult to retain in a core tube. (See vibracorer
for further details.)
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.
Bruce Robison and Kim Reisenbichler with an oversized Detritus sampler, which is used to collect larvacean houses. We will not be using it in the Gulf of California, but will have four smaller samplers that are otherwise identical. These D-samplers are patterned after the D-samplers developed by Harbor Branch Oceanographic Institution and enable us to collect delicate zooplankton without any damage.
This unique instrument measures the photosynthetic properties of phytoplankton continuously while this ship is in motion. This greatly increases the amount of data as well as the area that can be surveyed.
The science van includes space and many pieces of equipment that are necessary for processing samples on board the ship.
Heat Flow Probe
This special instrument lets us measure temperature in areas where normal probes would melt. Measuring 60 cm, this probe was originally developed for the submersible Alvin. MBARI scientists have used this probe before.
ICL (Inductive Coupled Link)
The ICL is a simple non-contact way to get data in or out of an instrument using a connection method that is within the dexterity capability of current mechanical manipulators. It works in air or water and can accommodate up to 9600 baud reliably. Please follow the link for a full description.
The laser raman spectrometer attached to the ROV Tiburon can be used to determine the chemical and physical properties of all kinds of samples—liquids, solids, or gases. In this case, it is being used to make measurements of the density of carbon dioxide as it combines with seawater to make a hydrate or clathrate.
The remotely operated vehicles that MBARI owns both use the 'toolsled' approach to facilitate mission objectives. The toolsleds are research-specific and are quickly and easily swapped out between missions. Each toolsled contains instruments that are designed for a particular research group. This midwater toolsled contains a High Frequency Suction Sampler (HFSS). You can see one of the 12 collection buckets in this image.
MBARI Water Sampler ("Plume Sniffer")
An in situ water sampler
and analysis system is shown mounted on the swingarm of the MBARI ROV Tiburon.
The sampler draws fluid from a point of interest once the inlet of the
sampling tube (3/8" dia.) is positioned by the scientist using Tiburon's
manipulator arm. The sample fluid is drawn past two instrumented flowcells
using a Seabird pump (SBE 5T). The first flowcell houses the optical path
of the ISUS sensor (In Situ Ultraviolet Spectrophotometer - green
enclosure) while the second flowcell houses the electrodes of the Eh
sensor (silver enclosure with blue endcaps) and a temperature probe.
The ISUS sensor directly measures in situ UV absorption spectra to determine the concentrations of dissolved compounds, in this case, bisulfide (HS-). ISUS was developed by Ken Johnson and Luke Coletti, both from MBARI. The Eh sensor measures oxidation/reduction potential (Eh) and was developed by Ko-ichi Nakamura from AIST in Japan. The water sampling system and ISUS sensor was constructed for this expedition by Luke Coletti with assistance from Mike Parker and Carole Sakamoto. Sensor logging software was done by Dale Graves and Ken Johnson.
Scientists will be collecting push cores using the ROV Tiburon to gather subsurface sediment samples. See the Leg 5 mission for additional photos. Also, see the vibracorer, which is attached to ROV Tiburon, for further details about how these cores are collected.
Blue water diving in the Pacific Gyre. We will be SCUBA diving on legs 3, 4, and 7. This is a highly specialized mode of scientific diving that lets researchers observe, experiment, and collect delicate midwater organisms in situ.
As the name implies, this interesting looking instrument squeezes core samples to gather pore water and gas samples from the sediments.
Tiburon is shown here outfitted with four detritus samplers and 12 buckets on a rotating carousel that form the collection portion of the High Frequency Suction Sampler (HFSS). This sampler acts like a vacuum cleaner sucking up samples and depositing them into one of the 12 buckets.
thermocouple array consists of 8 thermocouples connected to two small
sensor modules that house batteries, a microprocessor, and a reference
thermistor. The inconel-sheathed thermocouples are encased in Ti tubes to
prevent corrosion. Data are recorded by a central data logger located at a
safe distance from the smoker and linked to the sensor modules via
inductively coupled links (ICL). The ICL is also used to allow real-time
access to temperature data so that the thermocouple arrays can be centered
over the orifices of the chimneys, and so that hours or days worth of
temperature readings can be downloaded without disturbing the chimney or
array. We are using these arrays to directly monitor temperature within
the walls of chimney as they are enveloped during the growth of a chimney.
The newly formed chimney will then be recovered and the solid material in
the immediate vicinity of each thermocouple used for enrichment cultures,
molecular phylogenetic approaches, fluorescent in situ hybridization with
16S rRNA-specific probes while splits of the same material will be fully
characterized geochemically in terms of its mineralogy, and chemical and
Vibracorer (Click image for larger view.)
vibracoring system can collect sediment cores up
to one meter in length from the ROV Tiburon. When the shipboard
scientists desire a sediment core, an aluminum core tube is placed into
the movable vibrating clamp by the ROV’s manipulator arm, and then
clamped into position. A hydraulic motor connected to the vibrating clamp
is energized, and the vibrations induced by the motor cause the core tube
to quickly penetrate into soft sediments. When either firm sediments or
rock is encountered, or the tube reaches its full penetration, the core
tube is removed from the sediment by a small hydraulic winch mounted on
the top of the guide frame. A finger-like device installed at the bottom
of the aluminum core tube, called a core
catcher, prevents sediment from falling out of the tube. Once a
core is collected, it is transferred to a nearby benthic
elevator that will carry a group of cores to the sea surface
for recovery by the R/V Western Flyer.
These sediment cores allow shipboard scientists to determine the types of sediment that occur below the seafloor, to perform geochemical and microbiological analyses of the water that is contained in the pore spaces around the sediment particles, and to collect and preserve infauna* living below the sediment surface.
*Infauna are any marine organisms that live in soft seafloor sediments. Common examples of infauna include: worms, clams, benthic foraminifera, and crustaceans.
Click here for a complete description of the fluid samplers from our previous West Coast cruise.
Also, follow this link for a diagram of the Seewald Fluid Sampler.