Evidence from his and other teams points to increasing numbers of common parasites as an important cause. However, the problems facing amphibian habitats really pose a poignant example of ecosystems out of balance because of human activity, according to Beasley, a professor of veterinary biosciences and executive director of the Envirovet Program in Wildlife and Ecosystem Health.
Beasley's main collaborators, postdoctoral researcher Anna M. Schotthoefer and Rebecca A. Cole, an adjunct professor of veterinary pathobiology at Illinois and scientist with the National Wildlife Health Center in Madison, Wis., say they agree.
A series of their research projects -- two published in 2003 and another that will appear as a book chapter this year -- dramatically refine the data on parasitic activity and argue that physically and chemically induced changes of aquatic habitats are taking a toll.
"We have to be asking what human activities are contributing to imbalances in these ecosystems to set the stage for more severe infections," Beasley said. "It's becoming a serious question of how we can better manage landscapes, streams, wetlands, ponds and lakes. Frogs are among the first animals that young children see in a healthy wild place, but they are not finding them in the same numbers as in past years."
Tadpoles of many species feed on algae and periphyton -- plant slime that grows on other surfaces -- converting the material into the protein, fat and other nutrients that are needed by other creatures higher in the food chain, Beasley said. Amphibians are clearly important players in ecosystem functioning, he added.
"The frogs that develop from tadpoles subsequently devour thousands of insects,"
Contact: Jim Barlow, Life Sciences Editor
University of Illinois at Urbana-Champaign