Landscape change in the Arctic has altered the historical range and distribution of terrestrial mammals, including moose and snowshoe hares, which have moved northward into tundra ecosystems during the 20th century. Recent field and remote sensing observations indicate that beavers (Castor canadensis) have also expanded their range from boreal forest to tundra ecosystems.

Beavers represent a novel disturbance to stream ecosystems in National Park Service (NPS) units of arctic Alaska, which is of great concern to local subsistence users and NPS managers.

This project will:

1. Map the timing and spatial extent of beaver pond formation across all parks of the Arctic
   Inventory and Monitoring Network.
2. Quantify the local and downstream effects of recent beaver pond formation on water
   quality and hydrologic conditions in arctic streams.
3. Assess how beaver-induced changes in water quality and hydrology affect fish growth
   and bioaccumulation of Hg.
4. Provide NPS managers with predictions of outcomes from management options for addressing this emerging issue with respect to water quality and subsistence activities.