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Stellwagen
Bank National Marine Sanctuary
SSE Accomplishments
Report
Ecology
of Fishes on Deep Boulder Reefs
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Scott
Gardner, Nutco, prepares Peter Auster for
a dive in the DeepWorker.
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Peter
Auster and James Lindholm, both from the National
Undersea Research Center at the University of
Connecticut, conducted a study of the habitat use
of fishes on deep boulder reefs using the
DeepWorker submersibles. Five daytime dives were
completed to assess species composition on
different parts of reefs, which were categorized by
habitat complexity. Preliminary analysis of data
from the submersibles, combined with previous
remotely operated vehicle (ROV) studies, indicates
that community composition was correlated with
habitat complexity across boulder reef structures.
Future studies are planned to determine how light
effects the distribution and behavior of fishes.
Light levels vary seasonally, by depth, and by
photoperiod. Dives both day and night will allow a
first order assessment of how reef strucutures are
used for shelter as well as foraging
areas.
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Launching
a remotely operated vehicle used in
habitat surveys
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Bioacoustic Research
During
the Sustainable Seas Expedition in the Stellwagen
Bank National Marine Sanctuary, a contingent of
students and teachers from the American School for
the Deaf in West Hartford, Connecticut assisted
principal investigator Peter M. Scheifele of the
National Undersea Research Center at the University
of Connecticut in conducting bioacoustic studies of
humpback whales. The goals of the research were to:
continue monitoring ambient noise levels in the
whale habitat areas; evaluate the contribution of
anthropogenic noise to the ambient noise; and
analyze a humpback whale phonation that is believed
to be associated with a potential new feeding
behaviour. The research was carried out aboard the
S/V Mimi.
Ambient
Noise Assessment. Noise
measurements were taken during the period July 9
through July 15, 1999. Although the analysis of
this year's noise levels is still in progress, the
noise levels for 1999 are thus far consistent with
those taken in 1997 and 1998. Some 230 discrete
noise samples were taken on this mission, each
sample being two minutes in length.
Contribution
of Anthropogenic Noise. Of
the total samples taken over half included the
contribution of nearby vessels and whales.
Individual analysis of vessels (most of which were
whale watching vessels) has not been completed. Of
significance this year are recordings of the New
England Aquarium twin-hulled, high speed catamaran.
This vessel uses a pump-jet system for propulsion,
and sound signatures of this type of vessel have
not been developed.
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Aggregations
of feeding whales were located from a
blimp.
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Potential
Humpback Whale Feeding Phonation.
Over the
last two years, recordings have been made of a
phonation that appears to be made during feeding
times for whales in the sanctuary. Given the
scarcity of pelagic prey species in the water
column it is thought that the whales are now
bottom-feeding on the American sand lance
(Ammodytes americanus). A study by Ivar G.
Babb and Peter M. Scheifele is currently underway
to determine if there is correlation between the
population of sand lance and the humpback whale. If
this is the case, we are speculating that the
whales may be learning to use sound (in the form of
this particular phonation) to move the sand lance
into the water column for feeding. This would
represent a significant modification to the
humpback feeding process. During this mission, the
research crew recorded the phonation of interest
repeatedly, again during feeding. They have begun
an acoustical analysis of the phonation and have
developed a "humpback whale phonation evaluation
and archive" system. This system will allow
phonations to be catalogued according to their
frequency, content, contour, duration, and
inter-phonation repetition rate. It also allows
phonations (such as the one in question) to be
analyzed for repeatability. This program
development is in progress.
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Peter
Auster being lauched for a dive in the
DeepWorker.
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