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North American beavers change functioning of subantarctic stream ecosystems

North American beavers change functioning of subantarctic stream ecosystems

Athens, Ga. – Research by UGA ecologists has determined that the introduction of the North American beaver (Castor cannadensis) into Cape Horn, Chile changes the functioning of the stream ecosystems. The research findings will be used for a regional invasive species management plan.

In the current issue of Oecologia, UGA Institute of Ecology assistant professor Amy Rosemond and UGA alumnus and current Institute of Ecology and Biodiversity postdoctoral fellow Christopher Anderson report that beaver invasion in Chile’s Cape Horn Archipelago results in a reduction in the diversity of stream-dwelling invertebrates. Curiously, they also found an enhancement of ecosystem function, in the form of greater production of invertebrates in beaver ponds. Typically, diversity and ecosystem function are positively related, although not in this case.

“Ecosystem engineers have the capacity to modify their environment in much the same way as those who are certified as civil, mechanical and biological engineers,” Rosemond explained. “This study showed that beavers, via their engineering activities, had profound effects on stream structure and function as invasive species.”

Primarily aquatic, the North American beaver is the largest rodent in North America and can be up to 70 pounds and three feet long. Fifty of these beavers were translocated to southern South America more than 60 years ago in an attempt to establish a fur trade industry that never actually flourished.

“As the world’s southernmost forested ecosystem, the Cape Horn Biosphere Reserve has no replicate,” said Anderson, who conducted the work as a UGA doctoral student and Fulbright Fellow. “Our study of the effects of beaver invasion not only provides information relevant to global ecological change, but also is the first study to address the function and processes of subantarctic freshwater ecosystems in southern South America.”

The work was facilitated in part by an international cooperative agreement between UGA and the Omora Ethnobotanical Park – University of Magallanes ( and ) in Puerto Williams, Chile, whose purposes include development of cooperative education and research programs between the two institutions. Thus far, five UGA undergraduate students and one graduate student have conducted research projects under the agreement.

With roots that date back to the 1950’s, the Institute of Ecology at the University of Georgia offers undergraduate and graduate degrees, as well as certification programs. Founder Eugene P. Odum is recognized internationally as a pioneer of ecosystem ecology. The institute is ranked eighth by U.S. News and World Report for its graduate program. As of July 1, the institute will become the Odum School of Ecology, the first of its type in the nation. For more information, visit