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January 29, 2002
Vol. 28, No. 14

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UT faces projected deficit; proposes $230 increase in student fees

Teresa Graham Brett named dean of students

Behavior of midwater fishes under Antarctic ice: Observations by a predator

Student group displays pro-life exhibit at West Mall area

Meningitis ruled cause of university student's death

New study examines effects of memory training

Endowed scholarship honors Myers

Researchers get $4.5 million to study child language therapy

New engineering chair made possible by $2.35 million gift

Global extinction rate reaches historical proportions

Special programs highlight celebration of Black History Month

Nichols named associate vice president for research

Texas Exes to honor teachers for their excellence as educators

Equal Employment Opportunity/Affirmative Action Program Policy Statement

University approves new policy for lighting UT Tower

Coral study challenges long-held theory on glacial cycles

UT research shows radiation zapping Mars may affect biological evolution

Growing number of U.S.-Mexican border residents using herbs to treat ailments

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Faculty Council

UT researchers receive $5.5 million to study effects of curricular changes in schools

Dana Center receives $94,000 award for math education

KUT adds Marketplace and The World to its program lineup

Arete: Harlan Miller

Critics program Viewpoint 2002 begins on Jan. 31

UT student returns home to conduct Corpus Christi Symphony in Rockport

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Behavior of midwater fishes under Antarctic ice: Observations by a predator

By Mary Lenz

Enlisting the help of 15 Weddell seals as under-water photographers, researchers from The University of Texas at Austin have discovered important new information about two ecologically important fish species living far beneath the ice pack in the dark and frigid waters of Antarctica’s McMurdo Sound.

weddell seal
Researchers used video sequences with synchronized positional data recorded by Weddell seals to describe behavior of two important fish species.
The research team discovered that silverfish (Pleuragramma antarcticum) migrate from depths of 827 feet at night to 1,132 feet by day. These movements coincide with changes in surface light intensity — even during Antarctica's months of constant sunlight. Toothfish (Dissostichus mawsoni), previously thought to be a species living in deep water, frequently occurred at shallow depths, between 39 feet and 591 feet. The depth at which they swim may also change with the time of day.

Dr. Lee Fuiman, a behavioral ecologist with the university, said this is the first research project to employ marine mammals to photograph an entirely different animal species by carrying a combination video camera and data logger.

fuiman
Fuiman
The research on the two fish species, the most important fish in the Antarctic in terms of abundance and crucial position in the food chain, is being published in the March issue of the journal Marine Biology.

Co-authors include Dr. R.W. Davis of Texas A&M University Galveston and Dr. T.M. Williams of the University of California Santa Cruz.

Fuiman, Davis and Williams previously have used seals, whales and dolphins as camera operators for research on their own species.

"Few details are known of the habits of Antarctic midwater fish, especially those living below the heavy pack ice and shore-fast ice, because they are difficult to capture or observe at depth," Fuiman said. "We used video sequences with synchronized positional data recorded by Weddell seals to describe such things as the location, movements, population trends and swimming behavior of the two fish species -- popularly known as Antarctic silverfish and Antarctic toothfish."

three fish
Seals 'observed' three different species of fish: a) Antarctic silverfish, b) Antarctic toothfish, and c) bald rock cod. Weddell seals frequently eat silverfish and rock cod and sometimes the much larger toothfish. Bald rock cod live just under the ice surface. Silverfish and toothfish inhabit much deeper and darker waters.

Previous knowledge of the habits of these two fish has been gained by trawling in ice-free areas, an inexact method at best, Fuiman said.

Fuiman said his team's observations were made by attaching video cameras and synchronized multi-sensor data recorders to seals. Data was recorded as the marine predators foraged under the ice.

The researchers used black-and-white video and miniature, low-light sensitive video cameras encircled by an array of near-infrared light-emitting diodes (LEDs).

Scientists believe that the infrared illumination from the LEDs was invisible to seals and fish and, thus, did not interfere with normal behavior. Yet, it enabled the camera to record images underwater in complete darkness to a distance of about one meter.

Ten male and five female seals made up the film crew. The sea mammal film crew members worked for four to five days at a time over three springtime field seasons at McMurdo Station. The research was supported by the National Science Foundation.

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