UW Student Addresses International Gathering of Ocean Scientists
By John Karl
MADISON, Wis. (11/15/99) — Ocean scientists can learn a lot from the humble lakes of the Midwest, and a University of Wisconsin student has been asked to teach them.
Chris Harvey, a limnology doctoral student at
UW-Madison, has been selected to represent the Great Lakes region at an international ocean science conference on November 21 in Gilleleje, Denmark. He will give two presentations at the Young Scientists Conference on Marine Ecosystems Perspectives, organized by the International Council for Exploration of the Sea (ICES).University of Wisconsin Sea Grant Institute, Harvey has studied the diets of lean and siscowet lake trout in Lake Superior. Understanding how their diets overlap, he says, is important for learning how each of these top-level predators affects the other—and how they both affect other levels of the food web in Lake Superior.
With support from the
Harvey says the Great Lakes and small lakes in Wisconsin and Michigan offer opportunities to learn things about food webs that are hard to study in the ocean.
"The oceans are enormous systems. You have all these things happening across all kinds of scales of time and space. When one thing changes, you don’t know what effect it has because so many other things are changing, too."
In small lakes, however, scientists can change something—by adding or removing predators, for example—and see what happens to the rest of the system.
Harvey will talk about what scientists call top-down effects on food webs—the idea that changes in the population of high-level predator fish can alter numbers of other species far below them on the food web.
Ocean scientists have most often studied things in the other direction, Harvey said. They have often assumed that the bottom links in the chain—like how much algae is available—determine what happens at all the levels above them. But Harvey says research in the Midwest has shown very strong top-down effects.
"For example, when lots of walleye were put into Lake Mendota [in Madison, Wis.], they ate the small fish that eat zooplankton," Harvey said. "So there were more zooplankton then, and zooplankton eat algae. So the zooplankton ate the algae, and the water cleared up. That showed that large predators can reduce algae."
The conference in Denmark "is intended to give young scientists an opportunity to participate in an international forum and to contribute to the international scientific work that forms the basis for managing the marine environment," according to ICES.
For More Information:
Stephen Wittman, Assistant Director for Communications, (608) 263-5371Conceived in 1966, Sea Grant is a national network of 30 university-based programs of research, outreach and education dedicated to the protection and sustainable use of the United States' coastal, ocean and Great Lakes resources. The National Sea Grant Network is a partnership of participating coastal states, private industry and the National Sea Grant College Program , National Oceanic & Atmospheric Administration , U.S. Department of Commerce. The University of Wisconsin Sea Grant College Program is administered by the Sea Grant Institute on the UW-Madison campus in Madison, Wisconsin.
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last updated 16 June 2000
posted 15 November by Karl
http://www.seagrant.wisc.edu/communications/news_releases/ChrisHarvey.html
