Degree Name

Master of Science (MS)

Semester of Degree Completion

2014

Thesis Director

Robert E. Colombo

Abstract

Although millions of dollars are spent annually on stream habitat restoration, the biological responses to these restorations are rarely monitored. I assessed the impact of habitat enhancement on fish and macroinvertebrate abundance and diversity in a small Midwestern stream. Fish and macroinvertebrate communities were sampled annually in two restored and two unrestored sites beginning two years before and continuing four years after restoration. Habitat heterogeneity increased in the restored sites following the restoration, but there were no significant changes in most macroinvertebrate and fish community indices. Macroinvertebrate composition was significantly different between spring and fall, but in general, assemblages within a year were more similar to each other compared to other years. These results suggest the effects of habitat enhancement in the restoration of macroinvertebrate community may have been overridden by basin-wide factors and interannual climatic variability. Fish relative density increased significantly after restoration in both restored and unrestored reaches, with a larger increase in restored reaches. However, there was no difference in the density or diversity of fishes between unrestored sites and restored sites. Fish community composition in the downstream control site was more similar to the restored sites, suggesting a carryover effect of the restoration to adjacent downstream area. These findings suggest the restoration had stream-wide effects on fish communities, with the restored reach directly contributing to the fish abundance and composition of adjacent unrestored reaches. Instream habitat restoration seems to affect fish and macroinvertebrate communities differently. Increase in habitat heterogeneity may support successful restoration of fish communities, but is largely ineffective in increasing diversity of macroinvertebrates.

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