Graduate Theses & Dissertations

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Assessing Emotion Processing Deficits in Youth
It is well-established that alexithymia in adulthood is a critical risk factor for numerous negative mental health and well-being outcomes. Although this area of research has begun to receive interest in earlier developmental stages, significant methodological limitations have been noted with current measures of alexithymia for adolescence. As such, the aim of the current thesis was to provide empirical evidence on the psychometric strength of a new adolescent measure of alexithymia, the Toronto Alexithymia Scale – Adolescent Version (TAS-A). Study 1 examined the construct validity of the TAS-A in relation to self and informant reported emotional intelligence (EI), while study 2 examined the predictive validity of the TAS-A in relation to adolescent problematic gambling and academic achievement. Adolescents completed self-reports of alexithymia, EI, and gambling behaviour, parents completed informant reports regarding their child’s EI, and academic records were obtained. Confirmatory factor analyses revealed significant relationships between adolescent alexithymia, and self and informant reported EI, indicating significant overlap in constructs. Adolescent alexithymia was also shown to be a significant predictor of problematic gambling and academic achievement; however, some interesting gender differences were observed (a pattern of results reported consistently in the adult alexithymia literature). Results are discussed in terms of methodological and clinical implications during the vulnerable developmental transition of adolescence. Author Keywords: adolescence, alexithymia, psychometrics
Assessing Measured and Perceived Risks to Drinking Water Sources
Microcontaminants originating from wastewater effluent and run-off from agricultural lands may be present in the sources of drinking water for rural and Indigenous communities in mixed-use watersheds. In this study, a convergent parallel mixed-methods design was applied to assess measured and perceived risks of contamination in the sources of drinking water for two communities; the Six Nations of the Grand River community in Ontario and the community of Soufriere in St. Lucia, West Indies. The overall goal of the project was to assess how measured and perceived risks of exposure to chemical and biological contaminants in drinking water sources could inform water management strategies for the communities. Quantitative data obtained from the analysis of water samples collected indicated that the highest levels and occurrence of fecal bacteria were found in the Soufriere watershed while the highest concentrations and occurrence of pesticides were found in the Grand River watershed. In the Grand River watershed, conventional treatment of water followed by activated carbon filtration and UV disinfection removed fecal bacteria and also removed many chemical microcontaminants with efficiencies as high as 98%. Data from both watersheds indicated that there was a strong positive correlation between the levels of caffeine and sucralose (i.e. indicators of wastewater contamination) in water samples and the levels of either Total Coliforms or fecal bacteria of human origin. Human health risk assessments of individual pesticides and pesticide mixtures performed by applying a hazard quotient (HQ) and hazard index (HI) model, respectively indicated that there were no apparent risks to human health from those microcontaminants. Qualitative data obtained from face-to-face interviews with water managers and health professionals working in the two communities, which were collected and analysed concurrently but independently, illustrated that there were cross-cultural similarities and differences in factors influencing the perceptions of risks associated with the sources of drinking water. These perceptions of risks were mainly influenced by factors such as heuristics or informal and informal reasoning, cognitive-affective factors, social-political institutions and cultural factors. These factors may have also influenced water managers and health professionals, as they often recommended more “soft” strategies for managing water resources in the communities. Key words: pesticides, fecal bacteria, microcontaminants, POCIS, measured risks, perceived risks, water management, First Nations, Grand River, Soufriere, St. Lucia Author Keywords: fecal bacteria, measured risks, microcontaminants, perceived risks, POCIS, water management
Assessing Molecular and Ecological Differentiation in Wild Carnivores
Wild populations are notoriously difficult to study due to confounding stochastic variables. This thesis tackles two components of investigating wild populations. The first examines the use of niche modeling to quantify macro-scale predator-prey relationships in canid populations across eastern North America, while the second examines range-wide molecular structure in Canada lynx. The goal of the first chapter is to quantify niche characteristics in a Canis hybrid zone of C. lupus, C. lycaon, and C. latrans to better understand the ecological differentiation of these species, and to assess the impacts of incorporating biotic interactions into species distribution models. The goal of the second chapter is to determine if DNA methylation, an epigenetic marker that modifies the structure of DNA, can be used to differentiate populations, and might be a signature of local adaptation. Our results indicated that canids across the hybrid zone in eastern North America exhibit low levels of genetic and ecological differentiation, and that the importance of biotic interactions are largely lost at large spatial scales. We also identified cryptic structure in methylation patterns in Canada lynx populations, which suggest signatures of local adaptation, and indicate the utility of DNA methylation as a marker for investigating adaptive divergence. Author Keywords: Ecological Epigenetics, Ecological Genetics, SDM
Assessing Quality of Life for the Urban Inhabitants of Classical Angkor, Cambodia (c. 802-1432 CE)
This thesis examines the interrelationship of urban planning and population health at the site of Angkor (c. 802-1432 CE), the capital city of the Classical Khmer state, now found within modern-day Cambodia. The inhabitants of Angkor developed a settlement strategy that relied on the dispersal of water management features, rice fields, temples and residential areas, to best utilize the spread-out environmental resources of the surrounding monsoon-forest climate. Thus, the main question to be answered by this thesis is this: did the city-planning practice of dispersed, low-density agrarian urbanism promote resilience against the disease hazards associated with tropical environments? To answer this question, methods involved creating assessing environmental and socio-cultural factors which habituated the urban inhabitants of Angkor’s relationship to disease hazards. The results of this assessment demonstrate that it was not until the last stages of Angkor’s urban development, when non-farming members of the population were concentrated into the “core” area of temples within city, that the city’s inhabitants’ vulnerability to infectious disease increased. As the city took a more compact settlement form, it was not as environmentally compatible as the earlier dispersed pattern. Significantly, archaeological case studies such as this can illustrate the long-term development and end-result of urban planning to deal with disease hazards, both in terms of everyday occurrences, as well as during crisis events, which has important implications for contemporary research on environmental disasters today. Author Keywords: Adaptive Strategies, Mainland Southeast Asia, Pre-industrial Urbanization, Resilience, Tropical Diseases
Assessing and Mitigation the Impacts of Mining-induced Flooding on Arctic-nesting Birds
Mining and resource development are growing industries in the Arctic, resulting in increased conflict with wildlife. Best practices for mitigation require an understanding of the potential ecological effects. One such effect concerns the flooding of terrestrial bird habitat from dewatering of lakes during mining pit development. I first assessed the efficacy of bird deterrents to mitigate impacts of mining-induced flooding on arctic-nesting birds at a gold mine in Nunavut. I used a Before-After Control Impact (BACI) design to determine changes in male territory densities, between year and treatment types (Control, High and Low Deterrent Intensity). Additionally, I assessed whether deterrents impacted daily survival rates of two passerine species, and the incubation behaviour of female Lapland Longspur. Finally, I quantified nest losses during the breeding season due to direct flooding of the tundra nesting habitat caused by mining operations. Deterrents did not affect male territory densities and neither deterrent treatment nor year affected the daily survival rate of nesting passerines. Female Lapland Longspurs exposed to deterrents exhibited more incubation off-bouts than control females. I documented six flooded nests. Deterrents used in this study appear to be ineffective in mitigating nesting in potential zones of impact. Incidental take accounted for about 1.2% of all nests found in the 0.48 km2 Whale Tail Lake study area. Author Keywords: arctic-nesting birds, audio deterrents, incidental take, mining and resource development, nest incubation, visual deterrents
Assessing basin storage
Water storage is a fundamental component of drainage basins, controlling the synchronization between precipitation input and streamflow output. The ability of a drainage basin to store water and regulate streamflow may mediate sensitivity to climate and land cover change. There is currently no agreement on the best way to quantify basin storage. This study compares results of a combined hydrometric and isotopic approach for characterizing inter-basin differences in storage across the Oak Ridges Moraine (ORM) in southern Ontario. The ratio of the standard deviation of the stable isotope signature of streamflow relative to that of precipitation has been shown to be inversely proportional to mean water transit times, with smaller ratios indicating longer water transit times and implying greater storage. Stable isotope standard deviation ratios were inversely related to baseflow index values. Basins demonstrating longer transit times were associated with hydrological characteristics that promote infiltration and recharge of storage. Author Keywords: baseflow, basin storage, climate change, mean transit time, Oak Ridges Moraine, stable isotopes
Assessing effects and fate of environmental contaminants in invasive, native, and endangered macrophytes
Macrophytes play an important role in aquatic ecosystems, and thus are integral to ecological risk assessments of environmental contaminants. In this dissertation, I address gaps in the assessments of contaminant fate and effects in macrophytes, with focus on glyphosate herbicide use for invasive plant control. First, I evaluated the suitability of Typha as future standard test species to represent emergent macrophytes in risk assessments. I concluded that Typha is ecologically relevant, straight-forward to grow, and its sensitivity can be assessed with various morphological and physiological endpoints. Second, I assessed effects from glyphosate (Roundup WeatherMAX® formulation) spray drift exposure on emergent non-target macrophytes. I performed toxicity tests with five taxa, Phragmites australis, Typha × glauca, Typha latifolia, Ammannia robusta, and Sida hermaphrodita, which in Canada collectively represent invasive, native, and endangered species. I found significant differences in glyphosate sensitivity among genera, and all species’ growth was adversely affected at concentrations as low as 0.1% (0.54 g/L), much below the currently used rate (5%, 27 g/L). Third, I assessed the potential for glyphosate accumulation in and release from treated plant tissues. I found that P. australis and T. × glauca accumulate glyphosate following spray treatment, and that accumulated glyphosate can leach out of treated plant tissues upon their submergence in water. Finally, I assessed effects of released glyphosate on non-target macrophytes. I found that P. australis and T. × glauca leachate containing glyphosate residues can stimulate the germination and seedling growth of T. latifolia, but can exert an inhibiting effect on A. robusta, although leachate without glyphosate caused similar responses in both plants. Additionally, I found no negative effects in A. robusta when exposed to glyphosate residues in surface water, or when grown with rhizosphere contact to an invasive plant that was wicked (touched) with glyphosate. My results show that non-target macrophytes can be at risk from glyphosate spray for invasive plant control, but risks can be mitigated through informed ecosystem management activities, such as targeted wick-applications or removing plant litter. Integrating contaminant fate and effect assessments with emergent macrophytes into ecological risk assessments can support the protection of diverse macrophyte communities. Author Keywords: Ecosystem management, Ecotoxicology, Glyphosate, Herbicide, Invasive plant, Species at risk
Assessing factors associated with wealth and health of Ontario workers after permanent work injury
I drew on Bourdieu’s theory of capital and theorized that different forms of economic, cultural and social capital which injured workers possessed and/or acquire over their disability trajectory may affect certain outcomes of permanent impairments. Using data from a cross-sectional survey of 494 Ontario workers with permanent impairments, I measured workers’ different indicators of capital in temporal order. Hierarchical regression analyses were used to test the unique association of workers’ individual characteristics, pre-injury capital, post-injury capital, and the outcomes of permanent impairments. The results show that factors related to individual characteristics, pre-injury and post-injury capital were associated with workers’ perceived health change, whereas pre-injury and post-injury capital were most relevant factors in explaining workers’ post-injury employment status and income recovery. When looking at the significance of individual predictors, post-injury variables were most relevant in understanding the outcomes of permanent impairment. The findings suggest that many workers faced economic and health disadvantages after permanent work injury. Author Keywords: Bourdieu, hierarchical regression, theory of capital, work-related disability, workers with permanent impairments
Assessing habitat suitability and connectivity for an endangered salamander complex
Habitat loss and fragmentation have significantly contributed to amphibian population declines, globally. Evaluating the state of remaining habitat patches can prove to be beneficial in identifying areas to prioritize in conservation efforts. Pelee Island, Ontario is home to a complex of salamanders including small-mouthed salamanders (Ambystoma texanum), blue-spotted salamanders (A. laterale) and unisexual Ambystoma (small-mouthed salamander dependent population). These populations have declined from intense landscape changes since the late 1800s, particularly from the historical drainage of wetlands. In this thesis, I evaluated the suitability and connectivity of habitat patches occupied by these salamanders to assess the size of, and dispersal capabilities between, remaining habitat patches. I found that there was a low amount of suitable terrestrial habitat available for this complex of salamanders, and existing habitat patches were small and isolated. Forested areas and non-breeding wetlands were considered to be suitable habitat when adjacent to existing breeding locations, suggesting that these habitats should be a focus for conservation efforts. Notably, intervention may be necessary to maintain this amphibian complex as many assemblages are isolated from one another and potential corridors currently consist of primarily unsuitable habitat. Given that much of the salamander complex is reliant on one species for reproduction, the long-term viability of this population of Ambystoma salamanders may rely on the enhancement of suitable habitat near current breeding sites by conservation organizations and local stakeholders. Ultimately, the approach used in this thesis emphasizes the value of evaluating habitat within a fragmented landscape to focus conservation efforts on imperilled species. Author Keywords: amphibians, connectivity, habitat suitability, landscape fragmentation, landscape resistance, unisexual
Assessing limnological characteristics of subarctic Québec thaw ponds and mercury methylation and methylmercury demethylation within their sediments
Thawing permafrost due to increasingly warm temperatures in northern subarctic regions is releasing mercury. The consequent formation of thaw ponds in the peatland palsa valley of the Sasapimakwananisikw (SAS) river in Whapmagoostui-Kuujjuarapik, Québec may provide a pool for MMHg formation and a potential risk to aquatic and human life, if these ponds facilitate MMHg export through hydrological connections to nearby waterways. Hg methylation and MMHg demethylation activities were examined in thaw pond sediments using a Hg tracer isotope incubation experiment. Analysis by coupling gas chromatography cold-vapor atomic fluorescence spectrophotometry (GC-CVAFS) with inductively coupled mass spectrometry (ICP-MS) techniques showed that MMHg was produced at a higher rate and within the first 2 h of incubation for both summer and winter seasons. For thaw ponds SAS1A, SAS1B and SAS2A, MMHg was formed at 0.0048 % h-1, 0.0012 % h-1, and 0.0008 % h-1, respectively during winter and at 0.0001 % h-1, 0.0016 % h-1, and 0.0010 % h-1, respectively during summer. Detection of MMHg losses were not as expected likely due to limitations of the combined tracer spike and overestimation of the in situ ambient mercury levels. Physical and chemical properties vary within ponds, among ponds and between winter and summer. SAS1B’s location nearby an organic carbon rich palsa may be ideal to study DOC – Hg interactions. Variability in pond characteristics including depth, surface area, age, pH, temperature, colour, oxygen concentration, total dissolved and suspended solids, conductivity, carbon, mercury, ammonium, calcium, magnesium, sulfate, total phosphorous, potassium, and sodium between seasons indicate the challenge of predicting future environmental impacts of climate change related thaw pond creation in the north. Author Keywords: demethylation, mercury, methylation, methylmercury, SAS, thaw ponds
Assessing the Clinical Usefulness of Three Tablet-Based Visuomotor Tasks to Evaluate Closed Head Injury
Evidence suggests that visuomotor system behaviour may be more sensitive to the prolonged effects of mild brain injuries than neuropsychological tests. We evaluated whether participants with a mild closed head injury (CHI) would show lingering visuomotor deficits, but not cognitive deficits, up to three years post-injury compared to participants with an orthopaedic injury and healthy controls. All three groups completed a tablet-based visuomotor assessment tool and a brief neuropsychological test battery. The CHI participants scored comparable to the control groups on the neuropsychological tests, but when assessed for visuomotor function requiring adjustment to a changing stimulus, CHI participants showed poorer performance than the control groups. Combined, these findings add to the evidence that CHI can lead to persistent visuomotor deficits that extend beyond those of neuropsychological tests. Therefore, visuomotor assessment should be included in brain injury and recovery evaluation, and this can be accomplished easily using tablet-based tasks. Author Keywords: closed head injury, neuropsychological assessment, recovery, tablet, traumatic brain injury, visuomotor
Assessing the Cost of Reproduction between Male and Female Sex Functions in Hermaphroditic Plants
The cost of reproduction refers to the use of resources for the production of offspring that decreases the availability of resources for future reproductive events and other biological processes. Models of sex-allocation provide insights into optimal patterns of resource investment in male and female sex functions and have been extended to include other components of the life history, enabling assessment of the costs of reproduction. These models have shown that, in general, costs of reproduction through female function should usually exceed costs through male function. However, those previous models only considered allocations from a single pool of shared resources. Recent studies have indicated that the type of resource currency can differ for female and male sex functions, and that this might affect costs of reproduction via effects on other components of the life history. Using multiple invasibility analysis, this study examined resource allocation to male and female sex functions, while simultaneously considering allocations to survival and growth. Allocation patterns were modelled using both shared and separate resource pools. Under shared resources, allocation patterns to male and female sex function followed the results of earlier models. When resource pools were separate, however, allocations to male function often exceeded allocations to female function, even if fitness gains increased less strongly with investment in male function than with investment in female function. These results demonstrate that the costs of reproduction are affected by (1) the types of resources needed for reproduction via female or male function and (2) via trade-offs with other components of the life history. Future studies of the costs of reproduction should examine whether allocations to reproduction via female versus male function usually entail the use of different types of resources. Author Keywords: Cost of Reproduction, Gain Curve, Life History, Resource Allocation Patterns, Resource Currencies

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Format: 2023/02/04