Campus News

Ecosystem engineers

North American beavers change functioning of subantarctic stream ecosystems

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

In the current issue of Oecologia, Amy Rosemond, an assistant professor at the Odum School of Ecology, and Christopher Anderson, UGA alumnus and current ecology and biodiversity postdoctoral fellow, 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 said.
“This study showed that beavers, via their engineering activities, had profound effects on stream structure and a function as invasive species.”

Primarily aquatic, the North American beaver is the largest rodent in North America and can weigh up to 70 pounds and be as long as three feet. 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 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. So far, five UGA undergraduate students and one graduate student have conducted research projects under the agreement.