Aquatic invertebrate communities in old, new, and re-formed beaver ponds in the Trail Creek watershed

Abstract

1. Beavers are ecosystem engineers. They alter the structure of their habitats when they cut woody vegetative material to create dams that result in ponds. Ponding slows water flow, resulting in fine sediment deposition. A wetland is created as the sediment continues to deposit. 2. The formation of these new water bodies creates new habitat for aquatic invertebrates. These ponds will have unique aquatic invertebrate communities that utilize the slow, deep, depositional habitat. Though the shifts in aquatic invertebrates between lotic and beaver-created lentic habitats are well studied, the effects of beaver pond age on these aquatic invertebrates is still very unclear. 3. Successional patterns of beaver ponds occur over time as wetlands continue to accumulate sediment, but how long this process takes is not known. Also, if beaver ponds are abandoned, they can turn back into stream habitats surrounded by meadows with high nutrient soil. How ponds that are old, new, and re-formed after abandonment differ in habitat structure is unknown, as is how potential differences affect the inhabiting invertebrate community. 4. The project objective was to determine if aquatic invertebrate communities differed in old, new, and re-formed ponds. We collected three aquatic invertebrate samples from different sections of each pond: one adjacent to the dam and two in random locations on the shoreline. Samples were taken using a D-net, sweeping along 1m for ten seconds. 5. Our findings will elucidate if there is a difference between communities in beaver ponds of different ages. We predict that due to the proximity of these ponds and similar habitat components, the invertebrate communities of the ponds will have no significant difference.