The effect of man-made and beaver dams on benthic invertebrate populations

Abstract

Dams have the ability to alter many aspects of natural hydrology, particularly benthic invertebrate communities. Man-made dams can cause many problems in lotic ecosystems via habitat fragmentation, substrate sifting, and chemical alteration. The effects of a beaver dam and a man-made dam on the Maple River were compared to determine which dam had a greater impact on the surrounding environment. After statistically analyzing dissolved oxygen levels, nitrate levels, and EPT taxa richness, it was determined that the man-made dam caused a significant change in the downstream EPT taxa richness of the stream, whereas the beaver dam had no significant effect. The cause of the increase in the EPT population downstream of the man-made dam appeared to be less related to a change in water quality than it was to a dramatic change in substrate quality. It is concluded that EPT Taxa richness alone cannot adequately assess water quality in lotic systems obstructed by dams.