River restoration efforts in the Columbia River Basin are commonly aimed at improving rearing habitat for fish and reducing mortality during other life stages. Habitat enhancement projects often include engineered logjams, but studies of the impacts of restoration on food webs are rare. Researchers investigated food-web dynamics and compared salmon production between control sites and sites with engineered logjams in the Methow River, WA. They surveyed fish and aquatic insects and built organic matter flow food webs for the main river channel and three side-channel habitats. In the side channel with engineered logjams, production of aquatic insects and juvenile salmonids increased over the course of two years. However, the increase was similar to variation that was observed in unrestored side channels and in areas where large wood naturally accumulated. These findings suggest that the ecological responses to restoration may be hard to discern given the natural variation and patchiness of river habitats. Accounting for this patchiness could improve studies of the efficacy of river restoration projects.
Paris, J.C., Baxter, C.V., Bellmore, J.R., and Benjamin, J.R., 2024, Food-web dynamics in a floodplain mosaic overshadowed engineered logjams- Consequences for salmon and river restoration: Ecological Applications, e3076. https://doi.org/10.1002/eap.3076
This United States Geological Survey news article "Food-web dynamics in the Methow River overshadow the effects of engineered logjams" was originally found on https://www.usgs.gov/news
