Electronic Thesis or Dissertation

Cadmium is a toxic metal that has detrimental effects on blood vessel development and function. To examine the effect of varying concentrations of cadmium on angiogenesis, two in vitro assays were used. First, developing yolk sac blood vessels were studied in gestation day 8 mouse embryos exposed to medium alone, 1.25, or 1.75 μM cadmium chloride (CdCl2). Embryos exposed to 1.25 μM cadmium experienced a significant increase in the number of vessels formed; however, they were smaller in size. Vessel morphology and signalling pathways were also investigated using the mouse aortic ring assay, with exposures of 0.0, 0.5, 1.0, 5.0, or 10.0 μM CdCl2. Samples exposed to 10 μM experienced a significant increase in vessel length. However, no significant differences in phosphorylated PTEN and AKT were observed. The results of this study suggest that low levels of cadmium may disrupt angiogenesis, particularly the development of the embryonic vasculature in the yolk sac.

Author Keywords: Angiogenesis, Cadmium, Embryonic Development, Teratogenicity, Vascular Development, Vasculogenesis

Animals are essential to freshwater biogeochemistry and productivity. Through their excretion, aquatic consumers release bioavailable nutrients and carbon that can vary with animal taxonomic rank, trophic position, and abiotic factors such as light and nutrient supply. In fresh waters, light and nutrient supply is often modulated by dissolved organic matter (DOM), a "murky" component in the water that gives it a brown color and that may indirectly affect animal nutrient and carbon excretion. Additionally, contaminants can impact animal physiology, altering metabolism and inducing stress, further affecting nutrient and contaminant excretion. The size and structure of the ecosystem, including community composition and biomass, can also impact the contribution of aquatic animals to the elemental pool. To understand these dynamics, I examined animal‐mediated elemental cycling in freshwater ecosystems across gradients of DOM concentration and composition and under contaminant exposure. I tested fish and invertebrate nitrogen, phosphorus, and DOM excretion across trophic positions during two sampling events in Lake Erie and in naturally DOM-variable streams and lakes. I also investigated the effects of chronic exposure to silver nanoparticles (AgNP) under environmentally relevant conditions on fish nutrient and silver (Ag) release. I found that aquatic animals can be a substantial nutrient contributor to the nutrient pool, particularly when their population biomass is high and ambient nutrient concentrations are low. I also detected nonlinear relationships between animal nutrient excretion and DOM characteristics that varied with taxonomic rank and trophic position and that dampened at larger ecological scales. Importantly, I identified several fish DOM excretion signatures that differed relative to ambient DOM and reported the first fish Ag excretion rates under AgNPs exposure. My results underscore the context-dependency and variability inherent in animal-mediated elemental cycling, highlighting the critical role of animals as both modifiers and conduits of nutrients, DOM, and contaminants in aquatic ecosystems.

Author Keywords: carbon, consumer-nutrient driven dynamics, ecological stoichiometry, nitrogen, phosphorus, silver nanoparticles

Phosphorus is the growth-limiting nutrient in freshwater environments. Dissolved organic phosphorus (DOP) refers to phosphorus within dissolved organic matter (DOM). Much of DOP is bioavailable, but it is poorly understood due to its complexity. This thesis explores the export DOP to Lake Erie from its tributaries, by investigating its speciation and concentration seasonally through weekly sampling of two tributaries and spatially across a river to lake transect. The rivermouth was a site of rapid transition, with lower concentrations of DOP in the lake than in the river and a greater proportion of P as DOP in the lake. Phosphomonoesters and aromatic DOM were coupled in the medium-sized Grand River, but not in the Upper Great Lakes-influenced Detroit River. Phosphodiesters and highly processed DOM were coupled in the Detroit River, but only during periods of low terrestrial inputs. Finally, we found that DOP is a large contributor to tributary phosphorus exports.

Author Keywords: dissolved organic matter, dissolved organic phosphorus, enzymatic hydrolysis, Lake Erie, nutrient export, rivermouth

The ancient Maya utilized aspects of their landscape within their religious rituals and ceremonies, including caves. The study of ritual cave use is known as Maya cave archaeology and archaeologists in this subfield suggest that all holes in the earth, be it natural or man-made were viewed as ritually significant spaces to the ancient Maya (Brady and Layco 2018). This thesis analyzes the mortuary pattern of a chultun in relation to natural cave rituals and/or burials to determine if both types of subterranean spaces functioned in ritually similar ways. Through excavation of a dual-chambered chultun at the site of Ka'kabish, this research established a parallel pattern between burials found in natural caves and the burials within a chultun/artificial cave. In so doing, this thesis provides much needed data in support of applying Maya cave archaeology theories and practices in the excavation and study of ancient Maya chultuns.

Author Keywords: Belize, cave burials, chultuns, Maya archaeology, Maya cave archaeology, mortuary archaeology

Wetlands are highly susceptible to the invasion of invasive species. The invasive hybrid cattail (Typha × glauca) is prevalent in the southeastern Prairie Pothole Region (PPR) wetlands. However, concerns arise about its recent proliferation in the northwestern PPR without maternal T. angustifolia. To determine taxonomic distribution, I used species-specific PCR-RFLP and microsatellite markers for genotyping 245 samples from 50 northwest PPR sites. I found 75% T. latifolia, 7% T. angustifolia, 16% T. × glauca, and 2% backcrossed or advanced-generation hybrids. F1 T. × glauca has expanded in western PPR without its mother species, and the low occurrence of later-generation hybrids indicates their recent range expansion. Additionally, T. angustifolia offspring make fewer hybrids, which suggests that reproductive barriers may limit hybridization between parental species. This study highlights the vulnerability of prairies to cryptic invasions by Typha hybrids, and early detection of invasive species is a critical factor in wetland management success.

The traditions of spirituality and meditation have been found to connect to psychological health in the form of increased happiness, empathy, and decreased anxiety. The present study aimed to better understand how these practices might connect to such beneficial outcomes. A sample of 363 undergraduate student participants completed a questionnaire that measured their meditation practice, mindfulness, spirituality, happiness, empathy, and anxiety. Contrary to expectations, meditators and non- meditators did not significantly differ in their psychological health outcomes. These findings have implications for how meditators and non-meditator groups should be differentiated in research. Regarding spirituality, the purpose and meaning and innerness dimensions of the construct significantly predicted happiness and decreased anxiety, while the unified interconnectedness dimension significantly predicted empathy. The transcendence dimension of spirituality did not significantly predict psychological health. This pattern of results has implications for spiritual care interventions that intend to augment psychological health.

Author Keywords: Anxiety, Empathy, Happiness, Meditation, Psychological health, Spirituality

This thesis explores the double-bind Indigenous Peoples encounter when pursuing post-secondary education in the field of Indigenous Studies. I argue that Indigenous voices deemed tolerable are incorporated into the commodification of Indigenous thought and experience for the Settler audiences who profit most from post-secondary institutions. My analysis discusses the possibilities for Indigenous Studies to navigate this parasitic relationship and assist Indigenous lives that academia renders unrecognizable. I examine my educational journey and conduct a literature review of the role that Settler Colonialism plays within Indigenous Studies. Through the use of critical self-reflexivity, this thesis employs Haudenosaunee political thought and Indigenous storywork to tell my personal narrative navigating the macro and micro dynamics within the academy that exploits Indigenous student's self-interest to maintain the Settler-Colonial status quo in higher education. I identify strategies to assist academics in conducting ethical research within Indigenous Studies and imagine insurgent education within the Canadian university.

Author Keywords: Commodification, Critical Indigenous Studies, Haudenosaunee, Settler Colonialism

Sexual agency is receiving more attention in sexuality research though its contribution to sexual well-being has yet to be determined. Sexual agency has been theorized as an overarching concept comprised of both internal and external components. Both feelings and behaviours in the sexual domain can be impacted by prevalent culturally prescribed sexual scripts. The present study assessed sexual assertiveness, sexual self-concept, and comfort in sexual communication (i.e., together conceptualized as sexual agency) to determine if greater levels of these indices led to more direct consent communication, more intrinsic motivations for engaging in sex, and more positive sexual evaluations. Analyses were run separately on two samples: a student and community participant pool. Results indicate that greater sexual agency predicts being more intrinsically driven to engage in sex, using more direct consent communication, and reporting more positive evaluations of one's most recent sexual encounter. Gendered analyses reveal that cismen and ciswomen have similar levels of sexual agency, and rate their encounters similarly. Having greater sexual agency was a better predictor of experiencing sexual well-being compared to gender. Implications for policy development and sexual education curriculum reform are discussed, and future research directions are suggested.

Author Keywords: Sexual Agency, Sexual Consent, Sexual Motivations, Sexual Regret, Sexual Well-being

Colonization has transformed the landscapes of the American Midwest and compromised the region's resources and ecologies. In response, governments, environmental scientists, and Indigenous nations have undertaken myriad efforts over the past century to restore Midwestern environments. Yet the appropriate goals and techniques for this work have been deeply contested. This thesis explores the scientific, political, and cultural meanings of ecological restoration in the region. Comparison of different forms of restoration reveals the contingency, malleability, and historical pitfalls of restoration knowledge and practices. By framing the pursuit as a problem of scientific, historical, or technical knowledge, practitioners have often neglected the political and cultural ramifications of restoration efforts. At the same time, restoration practices have influenced the intellectual, environmental, and political history of the Midwest in the twentieth century. The efforts of Midwestern scientists and public agencies have advanced wildlife and ecosystem conservation in the region, but have at times exacerbated environmental injustices and inequalities. More recent wild rice conservation efforts by Ojibwe governments demonstrate that, depending on how the framework has been constructed, ecological restoration has served as a tool for reclaiming Indigenous sovereignty as well as a vehicle for settler colonialism.

Author Keywords: American Midwest, conservation, ecological restoration, ecology, Indigenous history, settler colonialism

ABSTRACT

Development of Forest Degradation Indicators from Long-term Trajectories of Multispectral Satellite Images, and their Projections into the Future under Climate Change, in Ontario, Canada

Md. Mozammel Hoque

Ontario forests are affected by natural and anthropogenic disturbances leading to forest degradation, which significantly impact local ecosystems, health, safety, and economy. This thesis develops a methodology for the continuous assessment, mapping, and monitoring of present and historic (1972–2020) forest disturbances, and future forest degradation trends and projections, using remote sensing data, ground measurements, and predictive models in an Ontario forested area. After testing four supervised classification algorithms, support vector machine was found to be the most robust, consistent, and effective for land cover classification. Seven vegetation indices derived from Landsat and MODIS platforms were used to derive forest degradation indicators (FDIs), which were combined into one composite forest degradation indicator (CFDI) for each year, using the principal component analysis image fusion approach. The CFDI was the most informative indicator. The computed FDIs from available large multispectral image stacks were statistically related to historical climate variables. These relationships were used to project future FDIs related to climate variables derived from General Circulation Models through multiple linear regression models. Spatially-explicit maps of relevant climatic variables and of long-term historical forest degradation were developed from the LandTrendr trajectory analysis. Climate variables P, MA1, MA2, and CFDI were strongly correlated, allowing for the development of a model with a high coefficient of determination, R2 (0.93), and low RMSE (0.28) to predict future values. Forest disturbances (as CFDI) were also monitored from 1972–2020. Overall, these relationships allowed for to the creation of spatially-explicit, long-term historical forest degradation maps derived from the Landtrendr trajectory analysis. Historical and future forest degradation maps identified the areas with projected high vulnerability to climate change, as well as the actual and potential changes in forest cover under climate change. The results indicated 2050 will experience an average temperature increase of 3.0°C, projected yearly decrease in precipitation of 109.5 mm, evapotranspiration increase of 73.0 mm, and moisture deficits of 28.47 mm (MA1) and 37.60 mm (MA2), leading to increased forest degradation.

Author Keywords: Climate change impacts, Forest degradation indicators, Forest disturbance and degradation, Land cover classification, Projections of 2050 forest degradation under climate change, Remote sensing technology