Date of Award:


Document Type:


Degree Name:

Master of Science (MS)


Watershed Sciences

Committee Chair(s)

Phaedra Budy


Phaedra Budy


Mark C. McKinstry


Frank P. Howe


Stream fragmentation and non-native species introductions are among a suite of anthropogenic disturbances shaping the structure and function of freshwater ecosystems. The impacts of such alterations contribute to the global decline of stream fish biodiversity and may be synergistic in their effects. For example, the Colorado River basin’s unique native fish assemblage is imperiled not only by numerous dams and diversions, but also by threats of predation and competition for limited resources from non-native fish species. On the San Juan River, Utah, a recently formed fish barrier prevents upstream movement of native and non-native fish. The goal of this project is to weigh the relative benefit of excluding non-native species from the river upstream of the barrier versus the cost of also excluding native fish from their upstream populations. To accomplish this, we tested whether fish community metrics and species interactions differ between reaches above and below the waterfall to provide insight into how free movement of fishes may affect upstream native fish populations. Our results highlight the barrier shapes fish communities and limits potentially negative species interactions from propagating upstream.



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