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Assessing Ecological and Food Web Responses to Small-Scale Stream Restorations in Urban and Agricultural Streams
No full textUrban and agricultural streams across the Midwestern United States are vulnerable to elevated pollution, eutrophication, habitat simplification, and losses of sensitive species. Instream habitat restoration is increasingly used to mitigate the impacts of rapid land-use change. This study synthesizes habitat and biological responses from a 2020 urban stream restoration in the Saline Branch (Urbana, Illinois) and evaluates food web responses from both the Saline Branch and a 2010 restoration in Kickapoo Creek (Charleston, Illinois), an agricultural stream. In the Saline Branch, four years of fish and three years of habitat and macroinvertebrate pre-restoration surveys were compared to three years of post-restoration surveys at restored and reference sites. Although the Saline Branch exhibited relatively high habitat quality and biological integrity for an urban stream, restoration resulted in limited improvement and a shift toward more generalist and tolerant taxa. Fish, aquatic, and terrestrial invertebrates collected from both streams in 2023 were analyzed using stable isotopes of carbon (δ¹³C) and nitrogen (δ¹⁵N) to characterize food web structure. Stable isotope analysis indicated that restoration effects on food web structure varied by land use. Restored sites in the urban Saline Branch exhibited increased basal energy diversity and larger food web size, whereas food web structure in Kickapoo Creek was more strongly influenced by riparian extent than by restoration. These findings suggest that while small-scale restorations can enhance habitat and modify energy pathways, ecological recovery may require longer time frames and broader watershed-scale improvements. Together, these studies highlight the context-dependent outcomes of small-scale stream restoration
