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Wednesday, January 31 • 11:40am - 11:50am
LIGHTING TALK: Effect of Riparian Alteration on Brook Trout Populations, Invertebrate Communities, and Stream Morphology

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AUTHORS. Ryan Brown, William Fisher, Joshua Raabe, Kyle Herrman - University of Wisconsin-Stevens Point

ABSTRACT. Riparian vegetation influences stream morphology and provides a source of connectivity between aquatic and terrestrial ecosystems. Forested riparian areas are often associated with wider, shallower streams, whereas streams with grassy riparian areas tend to be more narrow and deep. Connectivity occurs when invertebrates from terrestrial ecosystems fall into streams providing a significant food source for trout and emergent aquatic invertebrates provide a food source for terrestrial organisms. Alterations to riparian vegetation can affect invertebrate communities, trout diets, and alter stream channel morphology. The objective of this study is to determine how riparian alteration and the addition of brush bundles effects Brook Trout Salvelinus fontinalis populations, invertebrate communities, and stream morphology in a northern Wisconsin stream. We sampled four sites with different types of riparian vegetation. Three sites have riparian vegetation that is either old growth forest, shrub (Tag Alder Alnus incana) or sedge meadow, and these are reference reaches. The fourth site is an experimental reach where Tag Alder was manually removed and used as brush bundles within the stream. We monitored changes in stream morphology, canopy cover, substrate, bank erosion, and riparian land. Aquatic invertebrates were sampled using a Surber sampler and D-net while terrestrial invertebrates were sampled using pan traps. Trout were sampled using an electrofishing depletion method and stomach contents were obtained using a gastric lavage. Preliminary results indicate the brush bundles are narrowing the stream while slightly increasing depth. The sedge meadow riparian area displayed the highest terrestrial invertebrate richness while aquatic invertebrate richness was similar among all sites. Diet analyses indicated that consumption of both aquatic and terrestrial invertebrates occurred throughout summer months in all sites. It is too early to determine the effects of the riparian alteration on trout diets and invertebrate communities; however, the effects of brush bundles are modifying channel morphology.  

Wednesday January 31, 2018 11:40am - 11:50am CST