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ID
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87021
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Also Known As
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P-21-87-MA
87021
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Abstract
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United States Geological Survey, Woods Hole, Massachusetts.
Chief Scientists: Dave Twichell, Ken Able, Rutgers
University. Photography, Sampling data (PhotoSea still
camera, Suction sampler, Pingers) of field activity 87021
(P-21-87-MA) in New England Shelf, Middle Grounds, Block
Canyon to Atlantis Canyon, United States, North America,
North Atlantic from 05/28/1987 to 06/03/1987
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Organization |
United States Geological Survey, Woods Hole, Massachusetts
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Project/Theme
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Habitat Ecology of Offshore Populations of American
Lobster
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Chief Scientist
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Dave Twichell
Ken Able
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Activity Type
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Photography
Sampling
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Platform
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John Wesley Powell
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Owner
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Usgs
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Submersible
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Delta
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Area of Operation
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New England Shelf, Middle Grounds, Block Canyon to Atlantis Canyon, United States, North America, North Atlantic, Massachusetts
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Bounding Coordinates
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42.75000
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-73.75000 -68.25000 |
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41.25000 |
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Ports
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LEAVE New London, CT
ARRIVE Woods Hole, MA
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Dates
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05/28/1987 (JD 148) to 06/03/1987 (JD 154)
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Analog Materials
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No analog holdings.
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Information Specialist
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Crew
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Dave Twichell
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Chief Scientist
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Ken Able
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Rutgers University, Chief Scientist
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Duncan Fitzgerald
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Boston University
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Chris Baldwin
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Boston University
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R. Slater
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DELTA pilot
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Equipment Used
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PhotoSea still camera
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Suction sampler
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Pingers
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Purpose
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The purpose of the cruise is two fold: first to study the
importance of the prized tilefish burrow as a lobster habitat, and second
to evaluate the extent and style of sediment reworking by organisms on the
outer shelf.
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Information to be Derived
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Samples and Chemical Analysis
Morphology
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Summary
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This study was conducted over the open shelf in the
Middle Grounds, the general area between Block and Atlantic Canyons. The
specific site was chosen based on our extensive sidescan sonar surveys
during 1984. We completed 14 dives, including one at night. Of these,
Lance Stewart conducted one to test NURP-designed gear and another in an
attempt to help URI scientists locate a missing scientific package. Most
dives were centered around 725 ft. (690-840 ft.) in an area with numerous
large tilefish burrows (approximately 10 ft. diameter) and abundant
lobsters. Two dives immediately inshore in more shallow water (345-385
ft.) found tilefish burrows but no lobsters. We observed 85 lobsters
during these dives. Most of these were moving over the open bottom as if
they were taking part in the inshore migration. Many others were found in
tilefish burrows and frequently lobsters and tilefish were observed
simultaneously in the same vertical burrow. These lobsters usually were
in larger alcoves in the upper one meter of the tilefish burrows. The
shape of these smaller burrows suggested that they were dug by lobsters.
Some lobsters were observed in abandoned tilefish burrows, particularly
those in which the subsurface clay was still exposed. Other lobsters were
observed in shallow bowl-shaped depressions as observed by other
researchers. The bowl-shaped depressions were apparently of their own
construction. The single night dive verified earlier observations in
previous years in which we observed a marked shift in the fish fauna
relative to dives during the day. This data along with extensive 35 mm
and video film are still being analyzed.
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Notes
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7 days at sea.
Observations from the DELTA submersible, bottom
photography, and sediment sampling comprise the bulk of our work. Some
pingers were placed for burrow location at a later date. Updated 02/25/09
by A. Orton for D. Twichell.
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Project Number
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Funding
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Got Help?
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For 87021, we would appreciate any information on -- analog materials, contract, days at sea, dive count, kms of navigation, national plan, NGDC Info, publications, scanned materials, seismic description, station count, station description, tabulated info.
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