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TRAVERSE CITY, Mich. (AP) — For more than a decade, people walking along Great Lakes beaches have come upon a heartrending sight: dozens, or even hundreds, of dead loons, gulls and other waterfowl — victims of food poisoning that paralyzed their muscles and eventually caused them to drown.
Scientists have long known the primary cause is Type E botulism, which the U.S. Geological Survey says may have killed 100,000 birds in the region since 2000. They have ideas, but no proof, about how the toxin works its way up the food chain.
Now, using time-tested methods and new technologies, they're coming closer to solving the mystery — a crucial step toward determining whether anything can be done to prevent future die-offs.
Florida Atlantic University recently reported progress in a first-of-its-kind effort to determine the paths of birds that washed onto beaches after dying in open water. Experts with the university's Institute for Ocean Systems Engineering placed stuffed bird carcasses into a laboratory tank and took water resistance measurements. The information will be combined with current and wind data in computer models that attempt to retrace the birds' floating routes.
Meanwhile, several USGS labs are studying waterfowl distribution and sampling sediments collected from Great Lakes bottomlands, hoping to pinpoint where the toxin is produced. Initial findings suggest loons and other species that plunge into the water to catch fish may be getting infected at deeper levels than previously thought.
"It's kind of like a detective story," said David Blehert, a microbiologist with the USGS National Wildlife Health Center in Madison, Wis. "You find a body somewhere. You want to find out where the incident took place. You look for clues on the body, you find a piece of hair, a piece of fiber, and trace it back to the location and hopefully find your culprit."