Date of Graduation

Summer 2014


Master of Science in Biology



Committee Chair

Daniel Beckman


native fish, trout introduction, diversity, flight initiation distance, Ozarks

Subject Categories



Salmonids have been introduced to Ozark streams since 1878 with few studies to date investigating the effects of trout introduction on native fish. Fish communities were sampled in the fall of 2013 to assess potential impacts of trout introduction on community assemblage and behavior of native fish. An index of biotic integrity (IBI) was used to compare assemblages between sites of trout introduction and contemporaneous controls. Habitat and water temperature data were collected throughout 2012 and 2013 for all streams sampled to assess influences of these variables on fish assemblages and behavior. Results indicated that streams receiving high densities of trout had lower IBI scores than controls. However, water temperature may have influenced this observation due to streams receiving high densities of trout having colder and less variable water temperature. Results of the behavioral study indicate that trout introduction had an effect on the flight initiation distance, a proxy of wariness, of rainbow darters, Etheostoma caeruleum, and orange throat darters, Etheostoma spectabile. The increased wariness observed in these species in trout streams could have long-term fitness consequences for these species.


© Joseph Tyler Johnson

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