University of Lethbridge Theses
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- ItemInfluences of terrain drivers on ecosystem dynamics in a post-fire mountainous environment: a case study in Waterton Lakes National Park, Canada(Lethbridge, Alta. University of Lethbridge, Dept. of Geography and Environment, 2025) Van Gaalen, Jessica F.; University of Lethbridge. Faculty of Arts and Science; Hopkinson, ChrisMountain headwater snowpack is a critical water resource for Southern Alberta, and therefore monitoring changes to environments which support snowpack accumulation is imperative for informing land and water management decisions. Wildfires, such as the 2017 Kenow Wildfire in Waterton Lakes National Park, significantly alter vegetation and hydrological patterns. Post-fire vegetation and snowpack were modeled and monitored using multi-spectral airborne lidar to detect changes in distribution relative to local terrain drivers over time. Multi-scalar monitoring of vegetation regeneration showed that vegetation is significantly recovering at field, drone, and airborne scales of measurement. The vegetation models were stratified by terrain to find that factors such as elevation and local microtopography are influential on regeneration patterns. Snowpack models were also stratified by terrain to find that snowpack depth is greater in burned than in unburned areas, and the snowpack maximum depths shifts upslope as vegetation recovers over time. Quantifying the influences of terrain drivers on early post-fire ecosystem recovery is critical for understanding how ecosystems can be expected to recover under climate change conditions.
- ItemEfficient heuristics for the consecutive zeros problem in sparse Jacobian matrix determination(Lethbridge, Alta. : University of Lethbridge, Dept. of Mathematics and Computer Science, 2025) Talukdar, Md. Asif; University of Lethbridge. Faculty of Arts and Science; Hossain, Shahadat; Benkoczi, RobertWe study the Consecutive Zeros Problem (CZP), which is an extension of the well-known maximum consecutive ones problem. CZP is interesting both from a combinatorial and a practical standpoint. Leveraging a priori known sparsity pattern of matrix A, we employ a state-of-the-art coloring/column partitioning algorithm to generate a seed matrix S, to obtain the compressed matrix B = A × S, using automatic differentiation (AD) or finite differences (FD) while significantly reducing the problem’s dimensionality. With the AD forward mode, the nonzero entries of A are mapped to the compressed matrix accurately up to the machine precision using Cn “forward passes”. This research aims to reduce the computation cost ( measured by the number of AD passes required to compress the matrix) further by solving the CZP (grouping the zeros in each row of B). The problem is cast as a variant of the Traveling Salesperson Problem (TSP). To solve the problem, we have designed and implemented heuristic algorithms, including Ant Colony Optimization (ACO) meta-heuristic and two variants of ACO (Zp-Hybrid and Zp-Estimator), and several greedy heuristics (Exhaustive Approach, Selective Exhaustive, and Single Attempt). The computational results from a subset of benchmark test matrices clearly demonstrate the effectiveness of the proposed approaches.
- ItemImpacts of maternal prenatal enrichment on offspring brain morphology and behaviour in the Long-Evans rat(Lethbridge, Alta. : University of Lethbridge, Dept. of Neuroscience, 2025) Cantwell, Erin; University of Lethbridge. Faculty of Arts and Science; Gibb, RobbinThe maternal environment significantly impacts fetal development, and much of the existing research is focussed on outcomes following negative maternal experiences rather than positive experiences like enrichment. Maternal exposure to positive experiences is under-investigated, leaving its potential benefits largely unexplored. Environmental enrichment (EE) is a non-invasive paradigm that utilizes physical, social, and intellectual stimulation to benefit subjects. EE has been found to produce significant changes in behaviour and neuronal morphology. This research explores whether there are any long-term neuroanatomical and behavioural changes in offspring following maternal prenatal enrichment (PE). Dams were housed in distinct conditions, either standard (control dams) or enriched (PE dams) housing, during pregnancy. A total of 37 PE pups and 32 control pups were used for behavioural testing. Offspring underwent behavioural tests during early life (Open Field Test [OFT]), adolescence (Elevated Plus Maze [EPM]), and adulthood (Whishaw Tray Reaching [WTR], Morris Water Task [MWT]). Animals were euthanized, and their brains perfused, extracted, and prepared for Nissl analysis. A pilot sample of 15 male offspring (8 control, 7 PE) were used for volumetric analysis in the mPFC and parietal cortex. No significant differences in OFT, EPM, or MWT were found between PE and control offspring, indicating PE had no significant impact on anxiety-like behaviour, exploratory behaviour, or spatial learning and memory. However, PE offspring were found to have a significantly higher number of total and successful reaches in WTR, despite no differences in accuracy or lateralization, which may indicate increased task engagement or motivation in the PE offspring. No significant differences were found in total volume of both the mPFC and parietal cortex in the PE offspring, suggesting that PE had no impact on the overall volume of these regions.
- ItemReproductive status of fathead minnows (Pimephales promelas) exposed to a combined municipal and agro-industrial effluent(Lethbridge, Alta. : University of Lethbridge, Dept. of Biological Sciences, 2025) Morales Urrutia, Rayen; University of Lethbridge. Faculty of Arts and Science; Wiseman, SteveMunicipal and industrial wastewaters are complex chemical cocktails, including personal-care products, pharmaceuticals, and pesticides, many of which are endocrine disrupting chemicals. Frank Lake is a multi-basin wetland in southern Alberta, Canada, restored to stable water levels in 1990 with the addition of a combined effluent from the town of High River and the Cargill beef processing facility. At high water levels, water from Frank Lake drains into the Little Bow River that ultimately drains into the Twin Valley Reservoir. The biological effects that input of largely uncharacterized chemicals might be causing in the wetland, river, and multi-use reservoir are unknown. The study objective was to assess the reproductive physiology of fathead minnows exposed to the combined effluent from High River and Cargill. Standard 96-hr and 21-day assays were performed to assess reproductive toxicity, with the 96-hr assays being completed three times over the 2024 summer season to quantify temporal variation in effluent toxicity. Fecundity was not affected with exposure. Males exposed to high effluent concentration had an increase in tubercle score, as well as a decrease in condition factor and fertilization success. Male minnows exposed to effluent also had decreased plasma concentration of 11-ketotestosterone and decreased transcript abundance of hsd11b. Temporal variation in endocrine disrupting potential of the combined effluent was observed with varying effects on health indices and gene expression in fish exposed to effluent collected at different points of the 2024 summer. This research expands the understanding of industrial and municipal effluent impact on aquatic ecosystems, including health of exposed biota, and could inform future management decisions regarding Frank Lake.
- ItemBackyard wilderness: an interdisciplinary investigation of the urban ecology of Lethbridge(Lethbridge, Alta. : University of Lethbridge, Dept. of Psychology, 2025) Armstrong, V. Leila; University of Lethbridge. Faculty of Arts and Science; Barrett, Louise; Henzi, PeterA century ago, nature was seen as unpredictable, dangerous, and chaotic, and the goal was to tame it, map it, and exploit it for its resources. Increasingly, this campaign was replaced by the need to protect and preserve. Nature is now often seen as a pristine retreat, a virgin wilderness in need of our stewardship. Both views share the perception that we exist outside of nature and act upon it. In this thesis, I address this dichotomy and advance Anna Lowenhaupt Tsing’s work on assemblages and collaborative survival. I consider art as research in two chapters, Chapter 2, “The Nature-Culture Divide: Making Change at the Unruly Edges,” and Chapter 3, “Beyond Boundaries.” These lay the foundation for the art-making components of the project, which are reported in Chapter 6, “Backyard Wilderness: the art.” Following this, I describe a camera trap study and two surveys conducted in Lethbridge, Alberta, in which I asked a series of questions regarding the prevalence of wildlife in the city, and resident attitudes toward wildlife. Finally, as noted above, my art project, Backyard Wilderness examines the narratives we construct around our relationships with urban wildlife with the goal of advocating for coexistence. Coexistence doesn’t have to be a simple celebration of the creatures that rummage through our trash cans or spray our dogs. Instead, cohabitation can be a realization that urban wildlife enhances our experiences of our yards and gardens and helps us to embrace more sustainable practices.