University of Lethbridge Theses
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- ItemCardiotoxicity and interspecies sensitivity of early life stage fish to polycyclic aromatic compounds(Lethbridge, Alta. : University of Lethbridge, Dept. of Biological Sciences, 2025) McKenzie, Kristin C. R.; University of Lethbridge. Faculty of Arts and Science; Wiseman, StevePolycyclic aromatic compounds (PACs) are a broad class of organic contaminants that are present in all types of hydrocarbon fuels and produced from the incomplete combustion of organic matter. During early development, PAC exposure induces sublethal and lethal toxicity in fish. Predictive tools such, as the target lipid model (TLM), have been developed to estimate these impacts. Although cardiotoxicity is a well-established outcome of early life stage crude oil and PAC exposure, few studies have compared cardiotoxicity endpoints across freshwater fish species, and applications of cardiotoxicity endpoints within a TLM framework remain limited. Therefore, the aim of this study was to compare lethal and cardiotoxicity endpoints of larval walleye (Sander vitreus), fathead minnow (Pimephales promelas), and rainbow trout (Oncorhynchus mykiss) following exposures to naphthalene, dibenzothiophene and benz(a)anthracene. Larvae from each species were exposed using a passive-dosing system to five serial concentrations of each PAC, with exposures initiated within 24 h post-hatch and terminated at seven days post-hatch. The TLM framework was able to effectively characterize lethality, bradycardia and ventricle to atrium length ratio (walleye only), enabling a critical target lipid body burden (CTLBB) for each endpoint and species. Although walleye exhibited significantly lower sensitivity to acute lethality relative to the other species, no significant differences between species were observed for bradycardia endpoints. Despite their high survival, walleye exhibited significant reductions in ventricle length and diminished cardiac function following exposure to PACs. This study is the first to successfully apply cardiotoxicity endpoints in fish to a TLM and the first to produce CTLBB data for walleye. Results from this study further support the integration of cardiac endpoints into TLM-based approaches for improving the prediction of sublethal impacts from oil spills.
- ItemResiliency and vulnerability of boreal peatlands to wildland fire: identifying patterns through depth of burn, carbon loss, and environmental controls(Lethbridge, Alta. : University of Lethbridge, Dept. of Geography and Environment, 2025) Nelson, Kailyn Dawn; University of Lethbridge. Faculty of Arts and Science; Chasmer, LauraBoreal peatlands are globally significant carbon (C) sinks that have accumulated C over millennia but are increasingly threatened by climate-driven changes in fire regimes and moisture levels. Soil C losses from peat combustion remain uncertain due to challenges in quantifying below-ground combustion, limiting representation in global C budgets and models. This thesis 1) quantifies spatial variability in C loss during boreal peatland fires, and 2) identifies ecological conditions driving variability and peatland resistance or vulnerability to combustion. Research integrates field data, bi-temporal airborne lidar, and statistical modelling from the 2016 Horse River Wildfire in Alberta’s Boreal Plains. A synthesis of existing knowledge produced conceptual models of pre- and post-fire feedbacks impacting peatland combustion and recovery. These frameworks define two conceptual peatlands: resilient – hydrologically connected with low soil bulk density and moderated water tables, resulting in low severity combustion and moisture-retaining negative feedbacks; and vulnerable – fragmented or drained, with high bulk density, fluctuating water tables, and shrub encroachment, resulting in deep burns and drying positive feedbacks. Lidar ground classification accuracy assessments across unburned and burned, regenerating peatlands revealed negligible mean offsets: 0.00 m in burned to 0.01 m in unburned peatlands, with RMSEs of 0.09 m to 0.19 m, respectively. These findings support the utility of lidar for detecting elevation changes from peat combustion. Using these validated data, depth of burn (DOB) was estimated across peatland types and ecotones, averaging 0.08 ± 0.06 m, with deepest combustion in bog ecotones (0.09 ± 0.07 m). Statistical models revealed that top drivers of DOB variability depended on peatland type. In bogs, DOB was associated with topography and morphology, while in fens and swamps, where groundwater connectivity reduces the influence of topography on water tables, differences were associated with vegetation, hydrology, and disturbance. C losses across peatlands estimated using field-based soil C data and lidar-derived DOB showed that soil C losses (-2.11 ± 5.09 kg m-2) were substantially greater than vegetation losses (-0.38 ± 0.32 kg m-2), with bog ecotones identified as hotspots for C combustion loss (-16.5 kg m-2). Comparison with Landsat differenced Normalized Burn Ratio (dNBR) revealed that while vegetation losses related moderately to dNBR, soil losses did not, demonstrating the limitations of optical indices for below-ground combustion. Comparisons with estimates from the Canadian Model for Peatlands highlighted the need to explicitly include ecotones in C models – particularly under a changing climate.
- ItemPerceived severity of workplace harassment and coping strategies: a gender-based comparative study(Lethbridge, Alta. : University of Lethbridge, Dhillon School of Business, 2026) Ezeachikulo, Ujunwa P.; University of Lethbridge. Dhillon School of Business; Nguyen, BrendaWorkplace harassment remains a pressing organizational concern, with growing attention on how individuals perceive and respond to such experiences across gender lines. Guided by the Transactional Theory of Stress and Coping, this study investigates gender-based differences in the perception of workplace harassment and the coping strategies employees employ. A total of 306 participants, balanced across gender identities, were recruited through Prolific to complete validated survey instruments, including the Negative Acts Questionnaire (NAQ-R) to assess perceived harassment and the Full COPE inventory to capture coping strategies. Independent-samples t-tests revealed no significant gender differences in overall harassment perception, suggesting that men and women report comparable levels of exposure and severity. However, differences emerged in coping responses. Women were more likely to rely on emotional coping strategies and showed a slightly higher tendency toward avoidance coping, though both genders reported similar engagement in rational, problem-focused coping. Regression analyses further indicated that harassment perception was negatively associated with job satisfaction, with coping strategies showing limited predictive power, while rational coping demonstrated a positive effect. These findings highlight the need for organizations to move beyond a one-size-fits-all approach when designing interventions. Tailored support systems that account for gendered coping tendencies can better equip employees to manage workplace harassment while preserving job satisfaction. This research contributes to both scholarly discourse and practical strategies for building inclusive and supportive work environments.
- ItemSomewhere in France: creating a research-based card game about morale in the Canadian Expeditionary Force during the First World War (1914-1918)(Lethbridge, Alta. : University of Lethbridge, Dept. of History, 2025) Braisher, Matthew; University of Lethbridge. Faculty of Arts and Science; Alexander, Kristine; Burton, ChristopherThis thesis examines the experience of Canadian soldiers in the Great War (1914-1918) through their writings, for a closer understanding of soldiers’ morale in the Western Front. The first chapter of this thesis focuses on morale, and what some of soldiers’ writings can tell us about their morale. The second chapter of this thesis discusses the creation, mechanics, and playtesting of the other portion of this project, my card game named Somewhere in France, which was made with the intention of “translating” my research into a new medium, as well as some of the pros and cons of creating a historical research-based board game.
- ItemAdvanced quadratic optimization based smoothing framework for curved path planning in sustainable agricultural operations(Lethbridge, Alta. : University of Lethbridge, Dept. of Mathematics and Computer Science, 2025) Fernando, Weerahannedige Dananjala Pokurumalie; University of Lethbridge. Faculty of Arts and Science; Hossain, Shahadat; Das, SauryaThis research introduces an advanced quadratic optimization framework for the creation of smooth, curvature-continuous, and steerable waylines in precision agriculture. The framework combines curvature control, coverage uniformity, and steering feasibility into a single mathematical model to reduce skips and overlaps during field operations. Three smoothing techniques; B-spline, Bézier, and Non-Uniform Rational B-Spline (NURBS) are applied and compared to determine their impact on curvature continuity and field coverage efficiency. An extensive sensitivity analysis is performed to understand the effect of swath width tolerance, angular deviation, objective function cost weights, number of characteristic points of the spline curve, and solver configurations using IPOPT and Gurobi. Additionally, a versatile reference-line propagation method enables waylines to be created from either the field boundary or an interior line, thus, increasing flexibility in irregular geometries. The findings reveal that the NURBS-based method offers the greatest geometric flexibility and the most effective field utilization when compared to the other tested methods. The framework is shown to be performant and stable across irregular real-world fields, consequently, it is a scalable and practical solution for optimization-driven path planning in agriculture aiming at sustainability.