Expedition to the Deep Slope

May 7 -- June 2, 2006

Video Highlights

The "Expedition to the Deep Slope" was the first systematic exploration
of hydrocarbon seep communities deeper than 1000m in the Gulf of Mexico.
Funded by the Mineral Management Service (MMS), the leader in supporting
the scientific characterization of seep communities in the Gulf of
Mexico, and the NOAA Ocean Exploration (OE), our diverse team of
scientists used the R/V ATLANTIS and the ALVIN submersible to dive on
sites never visited before by woman or man. The team assembled includes
scientists who have led the exploration, discovery, and study of the
Gulf of Mexico cold seeps for the last 20 years. Our time included
leading international seep scientists from Germany, France and Austria
to complement our expertise. On this cruise, geologists and geochemists
worked along side microbiologists, physiologists, and ecologists to
maximize what can be learned about the deep Gulf of Mexico cold seeps
and coral communities.

All video courtesy of Expedition to the Deep Slope

For more information, please see www.oceanexplorer.noaa.gov

ALVIN LAUNCH and DESCENT

The Deep Submergence Vessel (DSV) ALVIN can take 3 occupants to a
maximum depth of 4500m. Typical launches from the Woods Hole
Oceanographic Research Vessel *Atlantis* begin promptly at 7:45AM. The
ALVIN is usually in the water by 8:00AM. Two swimmers and a small
support boat assist with vehicle launch and recovery.

TUBEWORMS AND DANCING SHRIMP (CLOSE-UP)

On our first dive of the cruise at the Atwater Valley Site 340, the
ALVIN came across a large carbonate rock outcrop with a number of
chemosynthetic tubeworms, *Escarpia*, around the edges. On almost all
the tubes there were these 'dancing' shrimp, *Alvinocaris muricola*,
swimming around and hanging onto the tips. Associated with them were
tiny little amphipods swimming around the seawater above the tubes.

SHRIMP SUCTION

Scientists use the ALVIN suction device to slurp up several shrimp and a
small crab.

TUBEWORM STAINING

Scientists use a specially-designed container and blue clothing dye to
stain small stands of tubeworms bushes. When scientists return in one
year, they will be able to measure how much the tubeworms have grown in
a year and better estimate how long these communities might live.

MUSSEL COMMUNITY

Scientists use a combination of instruments to sample the organisms
living in and around the chemosynthetic mussel communities on the
seafloor. The video zooms out from a carbonate rock on the seafloor and
pans over a large mussel bed bordered by tubeworms.

MUSSEL AND SHRIMP (CLOSE-UP)

Close-up of chemosynthetic mussels and an *Alvinocaris muricola*,
shrimp.

MUSSEL FIELD AND BRINE FLOW

This video begins at the interface between a very extensive mussel bed
on the perimeter of a large mud flow and brine seep feature. These are
precisely the types of features that geologists onboard the ATLANTIS are
interested in finding. They represent very active venting of fluids and
sediment from the subsurface. The hydrocarbons contained in the vented
fluidized sediment provide the necessary resources for chemosynthetic
communities. As the camera pans to the right, we move away from the
flanks of the brine flow and into of what appears to be white
*Beggiatoa* bacterial mats.

BRINE LAKE

Scientists were astounded whey they discovered an 'lake' 2200m below the
ocean surface. Watch and listen as scientists witness an underwater wave
pass across the surface of the Brine Lake, at the interface between the
'lake' and overlying ocean. The wave is caused by pressure exerted by
the ALVIN as it sits atop the 'lake'.

METHANE VENTING

On this clip we see how a sediment core is taken out of Green Canyon.
Here the submersible pilot grabs one of corers with the manipulator and
pushes it into the sediment. These sediments are highly gas-charged, and
during the retrieval procedure the plume was emanating into the water
column. Most likely, this gas consists of methane, which is a very
strong greenhouse gas component.

DEEP CORALS

The one deep coral area that we focused on during this cruse was about
30 m in diameter with large rock outcrops and pillars extensively
colonized by many types of coral in an amazing array of colors. There
are yellow, pink, and white stony corals (scleractinians), orange sea
fans, white bamboo corals, and purple soft corals (all octocorals), plus
bright red black corals (so named for their beautiful black skeleton
underneath). This video clip shows several species of coral being
buffeted by strong currents. ALVIN pilots has their hands full trying to
maneuver around the large carbonate rock outcrops while being buffeted
by strong currents.

SWIMMING SEA CUCUMBER

This free-swimming sea cucumber was spotter from the ALVIN submersible.
Sea cucumbers are a common component of deep sea fauna. Unlike shallow
water animals these distant relatives of starfish are highly modified in
the deep sea, very colorful, and have exotic forms. Here is one that is
adapted to live a pelagic existence using highly modified tubefeet as
fins to swim near the bottom but still feeds on sediment on the seafloor
surface.

OCTOPUS: Scientists came across this 'narcotized' deep-sea octopus,
*Benthoctopus* sp., near the Brine Lake at 2330m. After seeing this
image, an octopod taxonomist on shore noted that there have been two
species of this genus described from shallower waters in the Gulf of
Mexico. This individual does not look like either and is likely a new
species.

ALVIN RECOVERY A series of video clips track the ALVIN as it breaches
the ocean surface of the ocean and is gently plucked from the water by
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