Graduate Theses & Dissertations

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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
Robust assessment of changes in wild mammal occupancy and activity relative to livestock and human disturbance
Anthropogenic activities such as human activity and livestock grazing are responsible for the global rise in disturbance impacts on wildlife and may underlie regional changes in biodiversity and ecosystem dynamics. Few studies have tried to disentangle the effects of different anthropogenic activities on wildlife behaviour, leaving a major gap in our understanding of conservation and management needs in disturbed areas. Human activity and livestock grazing are increasing in spread and intensity worldwide, thereby imposing pressure on both wildlife and natural areas. In this thesis, I used a camera trapping and occupancy modeling framework to assess whether human presence and livestock grazing had different impacts on site occupancy and activity of 10 wild mammal species, and how responses differed across taxa. Specifically, I predicted that all species would be sensitive to disturbance, but the type and intensity of the response would depend on disturbance type. I detected different responses to each disturbance type across species, but response type (displacement, activity change, crepuscularity) was not associated with species characteristics such as body. Importantly, disturbance intensity had a strong effect on wildlife activity levels, with many species exhibiting marked reductions in activity at high human or livestock disturbance intensity. It remains unclear whether all species’ responses are a direct consequence of disturbance versus indirect outcomes of shifts in behaviour of other species in the wildlife community (i.e., disturbance-related changes in prey activity may affect predator activity). Although on the whole disturbance intensity and effect sizes tended to be relatively low in this study, responses were exhibited across all species, implying that disturbance responses may be universal in wild mammals and largely underestimated. Ultimately, my work offers a template for the robust assessment of disturbance impacts on wildlife and provides new avenues for future research to deepen our understanding of wildlife sensitivity to anthropogenic activities. Author Keywords: activity, anthropogenic disturbance, human activity, livestock, occupancy, wildlife
Rethinking Subjectivity
The following thesis problematizes different theories of subject formation in relation to morality, accountability, and consciousness raising. Focusing on the conditions subjects emerge in, I argue that socially transformative subjectivities emerge in movement through spaces. The theoretical discussion departs from the premise that morally accountable subjectivities drive social change. The politics of positionality that anchor the subject in a particular social location conceptualize morality as the result of critical consciousness raising. The causal nature of the relationship between the subject’s ability to reflect back on itself and its moral capacity is problematic for it leaves the reflective subject in a position of epistemic and moral authority. Rather, a subject who does not fully know itself nor the conditions of its being has the ability to engage in moral inquiry. Grounding subject formation in epistemic uncertainty construes the subject as inherently accountable to other unknowing subjects. Transformative subjectivities emerge out of epistemic resistance and uncertainty. The particular understanding of morality that underlies the rethinking of my moral subject emanates from its relational constitution. A morality of care prioritizes the responsibilities a subject has to others. In the context of Covid-19, relational subjects act in accordance with a morality of care that leads them to intervene in the lives of others who are threatened by the virus and left unprotected by institutional structures. The desire to interfere is cultivated when subjects emerge in ontological fields generated through epistemic intervention. One way to create such interventions is through counter-hegemonic cultural production such as works of art. Author Keywords:
Desire to be Zine
This thesis explores access to feminist zine culture and community, specifically if, and how, access has been altered in the age of digital technologies and increased access to digital spaces. Results from a questionnaire completed by 8 young feminist zine-makers and readers of marginalized genders indicated that though the modern boundaries of what a zine is has been expanded to include e-zines, there remains a preference toward print zines in zine-making and reading practices. Results also revealed that while there is a preference toward accessing feminist zine culture and community in-person in theory, participants were more likely to access feminist zine culture and community online in reality. This project found that digital technologies and the Internet have affected feminist zine culture in multiple ways, ranging from the Internet creating a new access points to community, to the Internet making it easier to find, purchase, and distribute zines. Author Keywords: Digital Media, Feminism, Feminist Zine Culture, Feminist Zines, Materiality, Print Media
An assessment of the determinants of, or barriers to, successful municipal food waste management systems
Food waste (FW) disposal has negative implications for the social, economic, and environmental sustainability of communities. While some municipalities in Canada have made improvements to their FW management, others have not been successful. Considering the complexity of the issues integrated into municipal FW management (MFWM), a mixed methodological approach was used to understand the determinants of, or barriers to, successful MFWM systems. Methods included analysis of primary data from a household survey with a fixed response and open-ended questions, along with analysis of the secondary literature. A comparative analysis of the results was undertaken to determine similarities and differences between successful and less successful cases (Guelph and London, Ontario, respectively) and the broader empirical literature. The results suggest the success of MFWM is determined by the commitment of political decision-makers to implement FW policies backed by adequate regulations, high levels of perceived behavioural control over barriers to participating in MFWM programs, and the ability to finance user-friendly MFWM infrastructure. Recommendations are made to guide policies and programming on food waste management. Author Keywords: Components of Waste management System , Composting, Determinants of Success, Food Waste Reduction, Households Food Waste Behaviour, Municipal Food Waste Management System
Phytohormone-enhanced heavy metal responses in Euglena gracilis
Phytohormones, Cytokinin (CK) and Abscisic acid (ABA), are best known for controlling plant growth and stress responses; but they also mediate various developmental perspectives in alga. Yet, their mode of action in algal adaptive strategies to heavy metal responses, their involvement in orchestration of phytohormone crosstalk remain largely unknown and a molecular framework of phytohormone-controlled heavy metal uptake is absent. I found that three metals known globally to contaminate aquatic ecosystems, nickel (Ni), lead (Pb), and cadmium (Cd), cause changes in the levels of endogenous CKs, ABA, auxins, and gibberellins (GAs) in the green alga Euglena gracilis. Exogenous ABA or CK (trans-zeatin) alleviated metal toxicity through improved metal uptake efficiency and the regulation of the endogenous CKs activity profiles and GAs activity. This new evidence suggests that E. gracilis possesses functional phytohormone signals and metabolic pathways that are under metal stress response. Exogenously applied ABA or CK provoked the coordinated activation of metal uptake, likely via enhanced accumulation of metal binding compounds (i.e., proline, glycine, cysteine containing peptides), which are effective for metal sequestration. Using untargeted metabolomics analysis and functional annotation, this thesis further established that, CK and ABA modified pathways and metabolites, which were mainly involved in metal acclimation and resistance. These modified metabolites that were under the influence of phytohormones in algal cells growing under metal stress conditions were associated with: lipid pathways, riboflavin metabolism, biosynthesis of cofactors/vitamin, and carbohydrate metabolism. Bioactive secondary compounds (e.g., terpenoids, alkaloids, flavonoids, carotenoids) were also modified in algal cells treated with phytohormones. The present study highlights that ABA and CKs are important regulators of algal metal accumulation/acclimation strategies based on increased metal uptake, enhanced CK metabolism, regulation of hormonal crosstalk and regulation of some core cellular metabolism pathways, all of which improve metal uptake efficiency. Finally, our results suggest that ABA and CK form a novel strategy for metal bioremediation techniques and for sourcing microalgal value-added metabolites. Author Keywords: abscisic acid, cadmium, cytokinin, Euglena gracilis, lead, nickel
Landscape fitness
Variation in habitat quality and disturbance levels can strongly influence a species’ distribution, leading to spatial variation in population density and influencing population dynamics. It is therefore critical to understand how density can lead to variability in demographic responses for effective conservation and recovery of species. My dissertation illustrates how density and spatial familial networks can be integrated together to gain a better understanding of the influence of density on population dynamics of boreal caribou. First, I created an analytical framework to assess results from empirical studies to inform spatially-explicit capture-recapture sampling design, using both simulated and empirical data from noninvasive genetic sampling of several boreal caribou populations in Alberta, Canada, which varied in range size and estimated population density. Analysis of the empirical data indicated that reduced sampling intensity had a greater impact on density estimates in smaller ranges, and the best sampling designs did not differ with estimated population density but differed between large and small population ranges. Secondly, I used parent-offspring relationships to construct familial networks of boreal caribou in Saskatchewan, Canada to inform recovery efforts. Using network measures, I assessed the contribution of individual caribou to the population with several centrality measures and then determined which measures were best suited to inform on the population demographic structure. I found substantial differences in the centrality of individuals in different local areas, highlighting the importance of analyzing familial networks at different spatial scales. The network revealed that boreal caribou in Saskatchewan form a complex, interconnected familial network. These results identified individuals presenting different fitness levels, short- and long-distance dispersing ability across the range, and can be used in support of population monitoring and recovery efforts. Finally, I used a spatial capture-recapture analytical framework with covariates to estimate spatial density of boreal woodland caribou across the Saskatchewan Boreal Plains, and then reconstructed parent-offspring relationships to create a familial network of caribou and determined whether spatial density influenced sex-specific network centrality, dispersal distance, individual reproductive success, and the pregnancy status of females. I show that caribou densitygreatly varied across the landscape and was primarily affected by landscape composition and fragmentation, and density had sex-specific influences on dispersal distance, reproductive success, and network centrality. The high density areas reflected good-quality caribou habitat, and the decreased dispersal rates and female reproductive output suggest that these remnant patches of habitat may be influencing demographic responses of caribou. Author Keywords: boreal caribou, density, familial networks, population dynamics, rangifer tarandus caribou, spatial capture-recapture
Using genomic and phenotypic data to explore the evolution and ecology of the North American mountain goat
Evaluating the impact of climate change is arguably one of the main goals of conservation biology, which can be addressed in part by studying the demographic history of species in the region of interest. In North America, landscape and species composition during the most recent Pleistocene epoch was primarily influenced by glaciation cycles. Glacial advance and retreat caused species ranges to shift as well, leaving signatures of past population bottlenecks in the genetic code of most species. Genomic tools have shown to be important tools for understanding these demographic events to enhance conservation biology measures in several species. In my thesis I first reviewed the state of ungulate genomics, with a focus on how such data sets can be used in understand demography, adaptation, and inform conservation and management. Importantly, the review introduces key analyses like the pairwise sequentially Markovian coalescent and features like variation in antlers and horns and selection pressures that are used throughout subsequent chapters. Using the North American mountain goat as a model species, I then explored the genomic and phenotypic variation in this alpine specialist mammal. Starting with the generation of the first genome assembly for the mountain goat, I identified genes unique to the mountain goat and modeled demographic history going back millions of years using a pairwise sequentially Markovian coalescent approach. Species’ effective population size generally paralleled climatic trends over the past one hundred thousand years and severely declined to under a thousand individuals during the last glacial maximum. Given the biological importance of horns in mountain goats and the recent scientific interest in genetic basis of headgear, I analyzed over 23,000 horn records from goats harvested in British Columbia, Alaska and Northwest Territories from 1980 to 2017. Overall, variation in horn size over space and time was low; goats harvested further North had shorter horn lengths and smaller horn circumferences in one year old and 4 years and older age classes and 4 years and older age class, respectively. Proximity of roads, which was used as an indicator of artificial selection, had a small effect on horn size, with larger horns being harvested closer to major roads. Finally, I used two range-wide genomic data sets sequenced with a whole genome re-sequencing and reduced representation approaches to provide estimates of genetic diversity, contemporary effective population sizes and population structure. These insights can help inform management and will potentially make an impact in preserving the mountain goat. Author Keywords: genome assembly, horn size, Oreamnos americanus, population demography, reduced representation sequencing, whole genome resequencing
Effects of Intensive Agriculture on Stream Nutrient Export in East-Central Ontario, Canada
Recent agricultural land use change in east-central Ontario, including the expansion of intensive agriculture (corn and soybean crops) and tile drainage (TD) infrastructure, may alter the fluxes of both phosphorus (P) and nitrogen (N) to the Lower Great Lakes. Through intensive monitoring of several sub-watersheds that encompassed a range of row crop and TD extents, this study examined differences in stream N and P concentrations both seasonally and during variable flow conditions, to better understand land use/land cover (LULC) relationships with nutrient export. There was no clear relationship between total P (TP; concentration or export) and agricultural LULC, and instead, TP delivery was highly sensitive to flow events, and TP concentrations (especially particulate P; PP) were significantly higher during event flow compared with baseflow. In contrast, the dissolved fraction of P (total dissolved P; TDP) and dissolved nitrogen as nitrate (NO3-N) were not sensitive to flow, but were instead positively related to row crop agriculture, and associations between NO3-N concentrations/export and tile-drained row crop area were particularly strong (concentration r2 = 0.93; export r2 = 0.88). Regression relationships showed that with every 10% increase in row crop area in watersheds, NO3-N and TDP flow-weighted concentrations increased by 0.34 mg/L and 1.5 µg/L, respectively. As well, the same 10% increase in row crop agriculture translated to an increase of NO3-N export of as much as 130 kg/km2. Geospatial records of TD are incomplete in east-central Ontario, which presents challenges for evaluating the contribution of TD to nutrient export. Understanding the response of nutrients to changes in agriculture and agricultural practices is an integral part of watershed management as rapid changes in both urban and agricultural LULC continue to put pressure on water quality in the Lower Great Lakes. Author Keywords: East-Central Ontario, Nutrient Export, Row crops, Streams, Tile Drainage, Water Quality
Finding Community
This thesis explores the history of the Indigenous child welfare system in Manitoba and the effects of the Millennium Scoop on children in care. My research question is: what was the experience of children in care in Manitoba from 1990 to 2015? A related question is: how do survivors find healing? The thesis begins with a discussion of the history of acts, policies, and practices that began with the Indigenous child welfare system during the running of Residential schools. Then the acts, reviews, and policies that have shaped the child welfare system in Manitoba are discussed more thoroughly. The focus of the thesis is on the stories of Phoenix Sinclair, Tina Fontaine, and Natasha Reimer. I share their stories and provide an analysis of how the child welfare system has affected their lives. The negative effects of being a child in care are numerous. Being a child in care leaves behind grief, loss of identity, and loss of security. The systemic issues of the child welfare system include inadequate funding, overloaded case workers, staff burnout, and a lack of transparency. These overarching failures translate into the failure of children in care: details are overlooked, wrong decisions are made, and children are left to fend for themselves. Or they fall into the cracks and do not receive adequate care. This then translates into the deaths of children in care, or they are left to navigate life on their own and forced to create their circle of supports. Despite all the complications and negative impacts, some children can succeed while in care. Natasha’s story is a perfect example of such resilience. Author Keywords: child welfare, indigenous studies, millennium scoop, sixties scoop
Combining Line Transect Sampling and Photographic-Identification Surveys to Investigate the Abundance and Distribution of Cetaceans
Line transect sampling and photographic-identification (photo-ID) are common survey techniques for estimating the abundance and distribution of cetaceans. Combining these approaches in the field (‘combined LTPI’ surveys) and using data from both components has the potential for generating comprehensive ecological knowledge that can be far more valuable than when these techniques and their data are used independently. In this thesis, I evaluated the results and conclusions from these two methods, used singly and in tandem, by investigating the population dynamics of two humpback dolphin (Sousa chinensis spp.) populations: the large and widely distributed Chinese white dolphin (S. c. chinensis) of the Pearl River estuary (PRE), and the small and geographically isolated subspecies of Taiwanese white dolphin (S. c. taiwanensis) in the eastern Taiwan Strait. Data from combined LTPI surveys in Hong Kong waters, at the eastern edge of the PRE, revealed a shift in space use with individuals spending less time in these waters than at the start of surveys. Data from combined LTPI surveys in Taiwan provided further support for a subspecies restricted to the central western waters, and identified a commonly used area at the northern part of their limited range. These two case studies demonstrated an overall efficacy of combined LTPI surveys in ecological studies of cetaceans. However, a multi-criteria analysis revealed that combined LTPI surveys with a line transect focus (e.g., Hong Kong) performed better than a LTPI survey with a photo-ID focus (e.g., Taiwan) when considering ecological aspects of the study populations, labour and data requirements, and ecological output. Even so, the photo-ID focus of Taiwan’s monitoring program led to better assessments of individual space use patterns, likely helped by the Taiwanese white dolphin population’s smaller size and intensive photographic effort. In both cases, the ecological output of combined LTPI surveys could be improved by expanding the study area or extending the field season or frequency of surveys. Overall, I showed that by following a set of general guidelines, different iterations of the combined LTPI approach (i.e., photo-ID focus or LT focus) can serve as powerful tools for uncovering multi-dimensional ecological information on cetaceans. Author Keywords: abundance, cetacean, distribution, line transect sampling, multi-criteria analysis, Photo-ID
Biodiversity patterns along a forest time series in a remediated industrial landscape
Sudbury, Ontario is an epicenter of research on industrially degraded landscapes. Regreening efforts over the past 40 years have changed the landscape, leading to an increase in forest cover in the “barrens”, that once covered more than 100,000 ha. This study characterized changes in plant and insect composition using a space for time approach in the pine plantations. A total of 25 treated sites were sampled and soil characteristics, understory plants and insect communities were assessed. All sites were contaminated with copper and nickel, but the metals had little influence on biodiversity. Vegetation diversity metrics were more strongly correlated with the pH of the organic soil horizons, while the insect community shows little response to site characteristics, and rather vegetation cover. Plant composition changes are similar to those in pine stands undergoing natural recovery and as liming effects fade there may be a decline in insect community richness. Author Keywords: Biodiversity, Heavy Metals, Mining, Remediation

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Graduate student theses produced at Trent University. You may also browse theses and dissertations by year, program, or author.

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