Scholarship & Research
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Item Environmental and molecular aspects of salmonid whirling disease(Montana State University - Bozeman, College of Agriculture, 1998) Clark, Stacie MarieItem Interactions among oligochaetes and a myxozoan parasite, Myxobolus cerebralis(Montana State University - Bozeman, College of Letters & Science, 2003) Steinbach, Leah Candace; Chairperson, Graduate Committee: Billie KeransItem Occurrence and seasonal dynamics of the whirling disease parasite, Myxobolus cerebralis, in Montana spring creeks(Montana State University - Bozeman, College of Letters & Science, 2004) Anderson, Ryen Aasheim; Chairperson, Graduate Committee: Tom McMahonSpring creeks provide a unique ecosystem for wild trout populations, characterized by high nutrient levels, chemical stability, steady flow regimes, and near optimum temperatures for spawning and rearing. However, several of these factors may accentuate whirling disease in spring creeks by providing favorable Tubifex tubifex habitat, the alternate host for the whirling disease parasite, and promoting the release of the infectious triactinomyxin (TAM) stage over prolonged periods. This study evaluated the prevalence and severity of whirling disease in nine different spring creeks and adjoining rivers or reservoirs in southwestern Montana. I investigated the influence of temperature, T tubifex abundance, water quality, and habitat characteristics on infection severity. Infection severity was measured with sentinel fish exposures in the spring and fall at all sites to evaluate the extent of infection. Seasonal dynamics of infection severity was assessed through monthly sampling in three spring creeks over a 20-month period. I found that infection severity was common (7 of 9 sites) but that severity among infected sites varied widely. Only five of nine sites had high infection levels (> 50% of sentinel fish exhibiting moderate to severe lesion scores ≥ grade 3) where population declines would be expected. The seasonal cycle of infection in spring creeks was much different than observed in non-spring fed streams as peak infection occurred during winter months, declined in late spring, and remained at low levels until fall when infection began to rise again. No significant relationships were found between infection severity and habitat features, T. tubifex abundance, and water quality, with the exception of infection severity and phosphorus in sites with moderate to high infection levels. Peak infections in spring creeks occurred at temperatures ranging from 6 to 12 °C. Redd counts and estimated emergence periods, correlated with sentinel fish exposure results indicated that fry emerging and rearing during late spring and summer are likely to avoid high infection, even in highly infected spring creeks. In contrast, given the high infection in spring creeks in late fall and winter, fry of fall spawning trout may be much more susceptible to infection in these systems.Item Efficacy of fumagillin and TNP-470 in preventing experimentally induced whirling disease in rainbow trout, Oncorhyncus mykiss(Montana State University - Bozeman, College of Letters & Science, 2001) Staton, Linda SueItem Quantitative assessment of Myxobolus cerebralis viability and infective success in the salmonid host(Montana State University - Bozeman, College of Agriculture, 2003) Hudson, Crystal JeanItem Spawning and rearing ecology of Madison River rainbow trout in relation to whirling disease infection risk(Montana State University - Bozeman, College of Letters & Science, 2000) Downing, Daniel CharlesItem Invertebrate aspects of whirling disease(Montana State University - Bozeman, College of Letters & Science, 2002) Stevens, Richard IrvingItem Factors affecting the resistance of juvenile rainbow trout to whirling disease(Montana State University - Bozeman, College of Letters & Science, 2003) Ryce, Eileen Karpoff NicolItem Effects of whirling disease on recruitment of brown trout in the Ruby River and Poindexter Slough, Montana(Montana State University - Bozeman, College of Letters & Science, 1999) Opitz, Scott TravisItem Correlations among environmental features, Myxobolus cerebralis infection prevalence in oligochaetes, and salmonid infection risk in the Madison River, Montana(Montana State University - Bozeman, College of Letters & Science, 2002) Krueger, Rebecca Caroline