Theses and Dissertations at Montana State University (MSU)
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Item Dam removals: an agricultural analysis(Montana State University - Bozeman, College of Agriculture, 2024) Bush, Nathan Alexander; Chairperson, Graduate Committee: Melissa C. LoPaloDam removals are occurring with increased frequency throughout the United States. 77% of all dam removal projects in U.S. history have occurred in the 21st century and the number of dams being removed each year is rising. Dams often play a key role in agricultural production, making it important for agricultural producers and policymakers to understand the effects of these removals as they become more common. This paper explores the causal effects of dam removal on agricultural productivity in the United States using a two-way fixed effects event study and an instrumental variable framework. Primary results of the analysis are mixed and differ based on exact specifications used but show initial evidence of per acre crop productivity increases and cash receipt declines following a removal. Further research is needed to explore the fine-scale effects of dam removals on individual agricultural producers and to expand on the preliminary causal relationships observed in this paper.Item Macroinvertebrate diversity, community structure, and dispersal are affected by tributary identity and confluence conditions in a regulated river(Montana State University - Bozeman, College of Letters & Science, 2023) Maguire, Zachary John; Chairperson, Graduate Committee: Lindsey Albertson; This is a manuscript style paper that includes co-authored chapters.Tributaries are essential components of freshwater ecosystems, playing a crucial role in maintaining connectivity and providing habitat for a diverse array of aquatic organisms. The role of tributaries in creating heterogeneity in physical conditions and food resources for fishes could be critical, yet little is known about how variable conditions in different tributaries in regulated river systems influence the mainstem. Using field observations in five tributaries on the Madison River, Montana, we found that tributaries in the same network and within relatively short distances of 60km varied greatly in their environmental conditions, macroinvertebrate densities, and macroinvertebrate community structure. Downstream of confluences macroinvertebrate richness increased overall, and per capita weight of drifting macroinvertebrates decreased overall. These findings suggest that confluences may act as hotspots for biodiversity in regulated rivers and introduce smaller bodied macroinvertebrates to the drift. The amount that a tributary influenced benthic richness and mean per capita weight in the drift downstream of its confluence was related to land use and abiotic factors within that tributary; both macroinvertebrate metrics significantly increased in magnitude downstream of confluences with higher percentage of US Forest Service land, cooler temperatures, decreased discharge, and increased elevation loss (i.e. steeper watershed slope). In contrast, tributaries that had a larger proportion of agricultural land, warmer temperatures, and higher discharge more strongly influenced benthic macroinvertebrate metrics. These tributaries supported higher benthic density and biomass downstream of confluences. Our results offer insight into the ways that tributaries can create heterogeneous habitats that in turn structure macroinvertebrate communities in mainstem rivers and suggest that conservation and restoration of these essential components of freshwater ecosystems is a well-spent endeavor in rivers with regulated mainstems. Future research will need to test the ubiquity of the patterns we observed in other river networks and under other global changes such as pollution, invasive species, and drought. Continued understanding of the importance of heterogeneity imparted by tributaries and their confluences on diversity, availability, and quality of food for threaten fishes is needed to guide restoration efforts aimed at improving river condition and resilience.Item Effectiveness of the nature-like fishway at Huntley Diversion Dam, Yellowstone River, Montana(Montana State University - Bozeman, College of Letters & Science, 2022) Anderson, Ian Richard; Chairperson, Graduate Committee: Alexander V. ZaleWe evaluated passage of a diverse fish assemblage through the nature-like fishway built around Huntley Diversion Dam, the uppermost of six low-head diversion dams on the Yellowstone River in Montana. Although nature-like fishways purportedly facilitate the passage of many species, relatively few have been evaluated, particularly on large rivers with unregulated discharge regimes. We examined seasonal and diel use of the Huntley fishway, quantified efficiencies and temporal metrics, and determined which factors influenced attraction and passage. We implanted > 3,500 fish of 14 species with passive integrated transponder tags, released most fish 250 m downstream of the fishway, and used stationary antennas to monitor movements of fish through the fishway in 2019 and 2020. Seasonal use of the fishway was generally associated with pre-spawning movements and occurred from April to August annually, and diel use reflected the known biology of each species. Attraction efficiencies were apparently low (usually < 50%), probably because of low motivation or the inability of fish to locate the entrance. Suckers released on opposite riverbanks downstream of the fishway were similarly successful at locating the entrance. Entrance efficiencies were usually > 90%. Both transit and passage efficiencies were usually > 60%, but fewer individuals (particularly among certain species) successfully passed than were able to transit to near the fishway exit. High river discharges were associated with decreased passage success and increased exit delays, probably because of problematic hydraulic conditions near the exit. Conditions throughout the rest of the fishway were appropriate, as most fish transited to near the exit in < 1 h regardless of discharge. Fourteen species passed upstream, demonstrating the functionality of nature-like fishways on large, unregulated rivers. However, the placement of such fishways must be thoughtfully considered to ensure that they remain effective over a wide range of environmental conditions.Item Hydraulics, hydrology, and resulting fish passage at the Huntley Diversion Nature-like Bypass(Montana State University - Bozeman, College of Engineering, 2020) Tupen, Haley Noel; Chairperson, Graduate Committee: Kathryn PlymesserDams and other instream structures have been constructed for hundreds of years in the United States for various purposes; these dams have the potential to 'disconnect' rivers and negatively impact fish upstream and downstream movement. Nature-like bypasses were created to facilitate movement around these structures and provide passage to a wide variety of morphologically different fish species. The Huntley Diversion Dam nature-like bypass was constructed in 2015 on the Yellowstone River, but its effectiveness has not yet been evaluated. This project aimed to evaluate its efficacy through monitoring and determining water stage, flow rates, channel roughness, and a detailed channel bathymetry. These data were then used in the creation of multiple two-dimensional hydraulic models encompassing the nature-like bypass channel and surrounding Yellowstone River area. Velocity results from these models were compared to species-specific swimming capabilities from literature for four Yellowstone River species. Additionally, hydraulics at the downstream bypass entrance were evaluated for disorienting hydraulic formations that might prevent fish from locating the bypass entrance. Velocity results indicate Sauger (Sander canadensis) may successfully ascend the bypass on all but five days of the modeled hydrograph and may face occasional difficulty in returning to their pre-spawning upstream habitat. Burbot (Lota lota), Channel Catfish (Ictalurus punctatus), and Smallmouth Bass (Micropterus dolomieu) are unlikely to successfully ascend the bypass for much of May, June, and July. This holds significant implications for Channel Catfish and Smallmouth Bass, both of which move upstream to spawn in the months of May and June. Hydraulics at the downstream end of the bypass indicate high attraction at high flows, but that lower flows are likely to create disorienting hydraulic characteristics at this bypass entrance and lead to low fish attraction.Item Potential impacts of altering discharge pattern from Hauser Dam, Missouri River, on young-of-the-year brown trout and rainbow trout(Montana State University - Bozeman, College of Letters & Science, 1985) Carty, Daniel GregoryDaily flow fluctuations would occur in the Missouri River between Hauser Dam and Holter Reservoir if Hauser Dam were converted to a hydroelectric peaking facility. To address potential impacts of fluctuating flows on free-swimming young-of-the-year (YOY) brown trout (Salmo trutta) and rainbow trout (S. gairdneri) emergence, growth, abundance, distribtion, movement, and habitat use were investigated. During reduced-flow tests stranding, isolation, displacement, and habitat changes were evaluated. Hydraulic modeling was used to predict changes in the quantity of usable habitat at different discharges. Recruitment from a tributary into the river was also monitored. Field data were collected between April 1982 and November 1983. Young-of-the-year brown trout were first observed in early April while YOY rainbow trout were first found in mid-June. Both species used relatively shallow, low-velocity water near shore where cover was abundant. Reduced-flow tests in August of each year revealed little stranding or isolation, and YOY trout were not permanently displaced from temporarily dewatered habitat. Hydraulic modeling predicted an increase in the quantity of habitat as discharge decreased, but field observations indicated a reduction in habitat quality. The tributary was found to be a relatively important source of recruitment to the river rainbow trout fishery but rather unimportant to the river brown trout fishery.Item Effects of gas supersaturated water on juvenile brown and rainbow trout(Montana State University - Bozeman, College of Letters & Science, 1988) Connor, William PaulSix bioassays were conducted at the Bozeman Fish Technology Center using juvenile brown trout (Salmo trutta) and rainbow trout (Salmo gairdneri) to determine the influence of fish size and species to gas supersaturated water. Juveniles of both species were exposed for 30-d to 104 + 1.2% (control), 112 ± 1.0% (medium treatment), and 125 + 0.7% (high treatment) atmospheric gas supersaturated water. No significant mortality occurred in the 112% treatment except during two tests when percent total gas pressure exceeded 113%, indicating that a critical threshold exists above this pressure. As fish grew they became more susceptible to 125% gas supersaturation. Total mortality and mortality rate were less when fish were small. The frequency at which emphysema occurred by body region also varied with fish size and smaller fish died with different external symptoms than larger fish. Larger fish were more likely to die faster than smaller fish and with no external symptoms. Daily mortality of brown trout exposed to 125% gas supersaturation was always significantly greater than for rainbow trout of similar size. Juvenile brown trout that survived exposure to 112% supersaturation showed greater incidence of external symptoms of GBT than juvenile rainbow trout of similar size. Juvenile rainbow and brown trout were exposed to supersaturations from 112% -118% total gas pressure to test for recovery. Recovery varied according to external symptom severity. Fish that did not recover usually had severe exopthalmia. Juvenile brown trout, repeatedly exposed to 118% gas supersaturated water, given 30-d to recover between exposures, developed more severe symptoms with each exposure. Sublethal effects of exposure to gas supersaturated water on growth, predation, and microbial infection were tested using fish exposed to supersaturations from 112 - 118% total gas pressure. Surviving fish developed new symptoms more often than recurring symptoms. Growth of survivors of 30-d exposure to 112% total gas pressure was not different from control fish. There was no difference in vulnerability to predation in circular tanks between juvenile brown and rainbow trout caused by exposure to gas super-saturation. Predation tests conducted in an artificial stream suggested some difference in susceptibility may be present, but data were not conclusive. Bacterial challenges indicated that juvenile brown trout exposed to 118% gas supersaturated water for 5-d were more susceptible to infection by Aeromonas hvdrophila than non-exposed fish.Item Distribution, relative abundance, and habitat associations of Milk River fishes related to irrigation diversion dams(Montana State University - Bozeman, College of Letters & Science, 2001) Stash, Sean WilliamItem Vibrational characteristics of three-dimensional solids, with applications to earth dams(Montana State University - Bozeman, College of Engineering, 1969) Frazier, Gerald Alvin