Theses and Dissertations at Montana State University (MSU)
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Item An analysis of whirling disease risk in Western Montana(Montana State University - Bozeman, College of Letters & Science, 2007) McGinnis, Stephanie Ann; Chairperson, Graduate Committee: Billie KeransMyxobolus cerebralis, the causative agent of whirling disease, has been a major contributor to the loss of young trout in numerous streams within the Intermountain West (Colorado, Idaho, Montana, Utah, Wyoming). Currently there are no effective management procedures for mitigating the effects of this disease because it is not fully known why the parasite has severe effects in some trout populations while remaining fairly benign in others. Characteristics of the parasite, hosts, environment, and their interactions, may partially explain varying responses of wild rainbow trout populations to whirling disease. The goal of this study was to examine possible contributors to, and indicators of, stream degradation and their relationship to whirling disease risk. Specifically, the objectives were to quantify relationships between whirling disease risk and 1) land use 2) biological stream integrity and 3) physicochemical parameters within four major drainages in western Montana. The hypothesis was that whirling disease risk is influenced by anthropogenic land use practices that create favorable habitat for the oligochaete worm host, Tubifex tubifex, which is reflected in the biological integrity and physicochemical features of the stream.Item Dynamics of the waterborne stage of Myxobolus cerebralis estimated directly by packed-bed filtration(Montana State University - Bozeman, College of Letters & Science, 2004) Lukins, Halcyon Josephine; Chairperson, Graduate Committee: Alexander V. ZalePast assessments of whirling disease infection risk on wild trout populations have relied on disease severity experienced by cultured fish exposed in sentinel cages or flatscreen filtration of Myxobolus cerebralis triactinomyxons. The former technique is indirect and inexpedient whereas the latter is imprecise and inaccurate. I examined spatial and temporal dynamics of Myxobolus cerebralis triactinomyxon concentrations directly using packed-bed filtration at five mainstem sites on the upper Madison River and at Willow Creek, a tributary to the Jefferson River. Packed-bed filtration provides accurate and precise estimates of ambient triactinomyxon concentrations. I also compared findings inferred from indirect sentinel-cage trials and my concurrent direct measurements. Triactinomyxon concentrations were consistently higher at Willow Creek than at the five sites on the Madison River, at which concentrations did not differ spatially. Concentrations at all sites peaked in spring and autumn. Variation in concentrations among five consecutive days was absent, but strong diel variation was evident; at Willow Creek, concentrations were elevated during periods of low light intensity. Indirect sentinel-cage sampling and simultaneous, direct packed-bed filtration largely corresponded, except in one low-temperature sample when a low percentage of fish became infected despite high concentrations of triactinomyxons. Packed-bed filtration proved to be a rapid, efficient, and effective method for assessing whirling disease infection risk among wild trout.Item Myxospore detection in soil and angler movement in Southwestern Montana : implications for whirling disease transport(Montana State University - Bozeman, College of Letters & Science, 2007) Gates, Kiza Kristine; Chairperson, Graduate Committee: Christopher S. GuyMovement of anglers among rivers in southwestern Montana presents a potential pathway for the spread of whirling disease and other aquatic nuisance species (ANS) on soil laden angling equipment. The objectives of this study were to 1) determine the effectiveness of a density extraction to isolate myxospores from soil and the effectiveness of polymerase chain reaction (PCR) at detecting M. cerebralis myxospores in soil; 2) quantify movement of resident and non-resident anglers in southwestern Montana and soil quantity carried on angling equipment; and 3) determine myxospore adherence to wading equipment materials. Myxospores were extracted from soil using a soil particle density separation technique. A single blind study was used for PCR experiments with varying quantities of myxospores and soil. Angler movement was assessed with a survey at fishing access sites on six southwestern Montana rivers. Soil samples were taken during the survey from boots and waders with a pressure sprayer to assess quantity of soil carried on angling equipment. Myxospore adherence to wading materials (lightweight, neoprene, rubber, and felt) was tested by exposing myxospores to material and rinsing with a pressure sprayer.