Impact of beaver dams on the Maple River West Branch.

Abstract

Beavers alter ecosystems through building dams. To determine if and how beaver dams affect stream ecosystems, we surveyed seven beaver dams in the West Branch of the Maple River (Emmet Co., MI), a cold water trout stream. We measured dissolved oxygen and water temperature at all dams and sampled macroinvertebrates above and below six active beaver dams. We found no statistical difference in temperature, dissolved oxygen, species diversity, and functional feeding groups of macroinvertebrates above and below dams. However, we found different macroinvertebrate communities above and below dams, and greater species richness and abundance downstream. Thus, beaver dams are producing an effect on the West Branch Maple River, and further samples should be taken to determine the extent of this effect and to sufficiently answer management questions in regards to trout populations.