Scholarship & Research
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Item Long-term effects of rotenone on the assemblage of aquatic benthic macroinvertebrates at a local level of disturbance(Montana State University - Bozeman, College of Agriculture, 2019) Schnee, Mark Erwin; Chairperson, Graduate Committee: Robert K. D. PetersonThe piscicide rotenone is an important and widely used tool for the conservation of native fishes, but comprehensive evaluations of aquatic benthic macroinvertebrate community response to rotenone exposure are lacking. Therefore, this study investigates the effect of rotenone on aquatic benthic macroinvertebrate (BMI) communities within the context of a watershed-scale restoration effort for westslope cutthroat trout (Oncorhynchus clarkia lewisi) conducted between 2007 and 2017. Long term pre- and post-treatment sampling in outlet streams of 13 alpine lakes quantified the response and recovery of BMI exposed to rotenone for periods ranging from weeks to a few months depending on the lake volume and environmental factors that influence the natural neutralization of rotenone. Spatial and temporal quantitative sampling was conducted at the lake outlets for 1 to 6 years before treatment and 2 to 8 years after treatment to capture the variability in density and diversity of the BMI assemblage. Analysis of changes to Ephemeroptera, Plecoptera, Trichoptera (EPT) density and diversity were used as a suitable representative for assessing effects to the entire BMI assemblage. Analysis of variance in EPT density and location shifts in variance in EPT diversity were used to test for significant changes to the EPT assemblage. Significant short-term reductions to EPT density were found 1 year post-treatment at 3 of the 13 lakes, 2 years post-treatment at 1 lake, and no significant reductions found at lakes with 3 or more years of post-treatment monitoring. Significant negative shifts in EPT diversity were found at 2 lakes with only 2 years of post-treatment monitoring, and no significant negative shifts in EPT diversity were found at lakes with 3 or more years of post-treatment monitoring. In all of the study sites, EPT density and diversity returned to baseline conditions within 3 years after treatment, demonstrating resiliency of these taxonomic communities to rotenone exposure.Item Identifying linkages between aquatic habitat, geomorphology, and land use in Sourdough Creek Watershed(Montana State University - Bozeman, College of Agriculture, 2004) McIlroy, Susan Kay; Chairperson, Graduate Committee: Cliff Montagne.Aquatic systems reflect the geomorphological and land use processes that shape them. System function, structure, and composition are driven by both autogenous and exogenous processes at small- and large-scales. Impacts often act synergistically, increasing the complexity and magnitude of their effects on aquatic systems. To assess these impacts, watershed scale studies are becoming more common, and an integration of research and management is beginning to emerge. Diverse user groups and differing agendas complicate watershed management and restoration, making a collaborative decision-making process imperative. Objectives of this study were to identify linkages between aquatic habitat, geomorphology, and land use in Sourdough Creek Watershed, explore potential land use impacts in the Lower Watershed, and identify a sustainable management plan for the watershed. Specific questions involved identifying potential westslope cutthroat trout reintroduction areas in the Upper Watershed and exploring statistical correlations between six land classes and the response variables of large woody debris and pool length. This study found suitable reintroduction areas as well as identified linkages between predictor variables and LWD and pool length across land classes. Although others have assessed aquatic habitat on a large-scale as well as identified potential management paradigms, this study integrates the two in order to provide a useful document for stakeholders and managers of Sourdough Creek Watershed.