Evaluating differences in water temperature and macroinvertebrate communities in BDA ponds, stream pools, and beaver dam ponds

Abstract

Beaver Dam Analogues (BDAs) are human-made structures mimicking beaver dams and are implemented in restoration projects to slow flow, aggrade sediment, and reconnect streams to floodplains or create wetland conditions. Despite the recent popularity of this technique, very little monitoring occurs at BDA sites. This study involved surveying and measuring beaver augmented BDA ponds, BDA ponds, and stream pools to assess differences in temperature and macroinvertebrate communities as an evaluation of how successful BDA installation has been. For each type of lentic habitat, we measured six different sites to get an accurate composition of the ecosystem for our data. Using temperature loggers and d-nets, we measured each restoration site over a period of 10 days. We found that the BDA ponds were comparable to beaver augmented BDA ponds in temperature, though the beaver-augmented ponds had a slightly lower mean daily maximum. In contrast, stream pools had a wide range of temperature fluctuation, with the lowest mean daily minimum and the highest mean daily maximum. The invertebrate community composition of each site was significantly different, with more lentic taxa in ponded sites than stream sites. The beaver-augmented BDA pond community was a more constrained subset of the BDA pond community, indicating that as those ponds change with beaver augmentation, the inhabiting invertebrates may be shifting towards more wetland-obligate taxa . These results suggest that BDA-based wetland restoration projects may require beaver to be successful or shorten the timeline to success.