August 23, 2004
Two UCSC graduate students receive grant for
marine ecology research
By Tim Stephens
Two UC Santa Cruz graduate students are among the winners of the 2004
Mia J. Tegner Memorial Research Grants in Marine Environmental History
and Historical Marine Ecology. Seth Newsome, a Ph.D. candidate in Earth
sciences, and Daniel Monson, a Ph.D. candidate in ecology and evolutionary
biology, will use their $5,500 grant to investigate historical changes
in the diets of killer whales during the past century.
|UCSC researchers will investigate possible changes
in the diets of killer whales over the past 100 years. Photo:
The Tegner grants are awarded specifically to help scientists document
the state of marine populations and ecosystems prior to large-scale
human impacts such as industrial fishing, whaling, and pollution. The
11 grants made this year were chosen from among 86 proposals from scientists
in 16 countries. The grants were announced last month by the Marine
Conservation Biology Institute of Redmond, Washington.
Newsome and Monson are teaming up to investigate a controversial hypothesis
regarding the ongoing collapse of marine mammal populations in the Bering
Sea and Gulf of Alaska. Over the past few decades, populations of pinnipeds
(seals and sea lions) and sea otters in this region have declined dramatically,
but the ultimate cause of the declines remains unclear. The "killer
whale predation hypothesis" holds that the depletion of whale populations
by industrial whaling forced killer whales to change their diets, relying
less on baleen whales as a food source and eating more pinnipeds and
sea otters instead.
The hypothesis is supported by indirect and circumstantial evidence,
but Newsome and Monson hope to find stronger evidence for a shift in
killer whale diets by analyzing the isotope composition of killer whale
teeth. Isotope analysis of an animal's tissues can yield clues to its
past diet because of natural variability in the abundance of rare isotopes
of elements such as carbon and nitrogen. The teeth of killer whales
are built up in layers deposited over an animal's lifetime, and the
isotope composition of each growth layer should reflect the animal's
diet at the time it was deposited.
Newsome and Monson have worked with colleagues at the National Marine
Mammal Lab to obtain about 100 killer whale tooth specimens from museum
collections. They have grouped the specimens to represent three relevant
time periods: 1900 to 1950, 1950 to 1970, and 1970 to 2003. They plan
to section teeth and analyze individual growth rings using a mass spectrometer
in the Stable Isotope Laboratory at UCSC.
Newsome has also been investigating the role that changes in productivity
may be playing in the decline of the Bering Sea ecosystem. In addition,
he has been working with Paul Koch, professor of Earth sciences, and
Diane Gifford-Gonzalez, professor of anthropology, to study historical
changes in populations of northern fur seals along the California coast
over the past 5,000 years, using isotope analysis of remains left at
middens by native people.
Monson earned his M.S. in marine sciences at UCSC in 1995, studying
sea otter populations with James Estes, adjunct professor of ecology
and evolutionary biology. He has been a research wildlife biologist
at the U.S. Geological Survey's Alaska Science Center since 1996 and
has returned to UCSC to pursue his Ph.D., with professor of ecology
and evolutionary biology Terrie Williams as his adviser. He has extensive
experience as a field biologist studying a variety of marine mammals
in Alaska and California.
The Tegner grants honor the memory of Mia J. Tegner, a marine biologist
at Scripps Institution of Oceanography who lost her life in 2001 while
carrying out research off southern California. She studied the ecology
of kelp forest communities and abalone populations and was particularly
interested in understanding how marine populations and ecosystems have
changed as a result of human activities. This pioneering research earned
her appointments as a Pew Fellow in Marine Conservation and as a Fellow
of the American Association for the Advancement of Science. The Mia
J. Tegner Memorial Research Grants were started by the Marine Conservation
Biology Institute with funding from the Oak Foundation, the Christensen
Fund, and the Weinstein Family Foundation.
The Marine Conservation Biology Institute is a nonprofit science organization
dedicated to advancing the science of marine conservation biology and
promoting cooperation essential to protecting, restoring, and sustainably
using the living sea.
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