Graduate Theses & Dissertations

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Breeding Phenology and Migration Habits of Whimbrel (Numenius phaeopus) in the Hudson Bay Lowlands, Canada
Understanding breeding and migration habits of Whimbrel (Numenius phaeopus) in the Hudson Bay Lowlands is important for the conservation of this population. I monitored Whimbrel at two breeding sites: the Churchill region of Manitoba and Burntpoint, Ontario. Annual average nest initiation timing was highly variable and successful nests were initiated significantly earlier than those that failed. Although nests were initiated significantly earlier at Burntpoint than Churchill, annual nest success quantified in program R MARK was similar across sites. Observed nest success rates were lower than historical records and most failure was due to predation. Annual nest survival varied widely and I used a generalized linear model to relate annual nest survival to annual average weather conditions. I observed weak relationships between annual nest survival and weather conditions in the northbound staging grounds. I tracked post-breeding migratory movements using the MOTUS radio telemetry system and observed consistent use of the mid-Atlantic coast of the United States during migration, especially among birds emerging from Churchill. In Burntpoint, I observed more variability in post-breeding migratory trajectories and significantly earlier post-breeding departure as compared to Churchill. The results of my study suggest differences in breeding and migration habits exist across nearby breeding populations, indicating that there is a need for population-specific conservation approaches for this declining species. Author Keywords: Migration, Movement Ecology, Nesting Ecology, Nest Success, Shorebird conservation, Whimbrel
Passage population size, demography, and timing of migration of Red Knots (Calidris canutus rufa) staging in southwestern James Bay
Many shorebirds rely on small numbers of staging sites during long annual migrations. Numerous species are declining and understanding the importance of staging sites is critical to successful conservation. We surveyed endangered rufa Red Knots staging in James Bay, Ontario during southbound migration from 2009 to 2018. We used an integrated population model to estimate passage population size in 2017 and 2018 and found that up to 27% of the total rufa population staged in James Bay. We also extended the model to incorporate age composition of the passage population. In future applications, this method could improve our understanding of the role of breeding success in population declines. We then estimated annual apparent survival from 2009 to 2018. Survival remained near constant, though lower than estimated elsewhere in the Red Knot range, which may reflect higher permanent emigration rates rather than truly lower survival. This work demonstrates that this northern region is a key staging site for endangered Red Knots and should be included in conservation planning. Author Keywords: integrated population model, mark-recapture, migratory stopover, shorebirds, species at risk, survival
Effect of Aging and Movement Variability on Motor Adaptation
Aging is associated with a multitude of changes, including changes in the motor system. One such change that has been documented is increased levels of inherent movement variability (the inability to consistently replicate movements over time) with increasing age. Previous research has had controversial findings regarding the effect that movement variability has on motor learning and motor adaptation. Some research suggests that movement variability is beneficial to motor learning, while other research indicates that movement variability is the by-product of a noisy motor system and is a detriment to learning new skills. How do changes in movement variability associated with aging affect the ability to adapt to a mass perturbation? We tested younger and older individuals on a mass adaptation task (applying mass to the lateral side of the arm to perturb inertial forces of the limb during reaches). We analyzed baseline levels of movement variability, learning during the adaptation block and how baseline levels of movement variability explained differences in learning. We focused on measures of accuracy, speed and precision. We found that younger individuals displayed greater levels of movement variability throughout the experiment and that they also learned to adapt to the mass perturbation more successfully than their older counterparts. Multi-joint movements displayed greater degrees of learning in comparison to single-joint movements, likely due to the difference in difficulty when completing the two movements. Taken together, our results suggest that purposeful movement variability may be beneficial to motor adaptation. Author Keywords: aging, mass adaptation, motor adaptation, motor learning, movement variability
What Nature is Best?
Connecting with nature benefits human and environmental health, however it is unclear whether certain types of nature influence people differently. Research has primarily focused on green spaces (vegetation-rich areas), but recent cross-sectional studies suggest that green spaces with blue space (natural water elements) may have additional well-being benefits. A quasi-experimental design compared the effects of green spaces with or without water on mood and environmental concern. Students (N = 193) were randomly assigned to walk along campus green (drumlin) or blue (river) spaces. Both walks improved students’ mood, especially for those who had a stronger preference for the area. Students in both conditions reported more sustainable behaviours when followed up one week and one month later, but decreased in nature contact and well-being. These findings highlight the challenges of promoting regular nature contact as a mood regulation strategy. Implications and future directions are discussed. Author Keywords: blue space, green space, nature connectedness, well-being
Effects of Recycled Media on Culture Growth and Hormone Profiles in Heterotrophic Euglena gracilis
The rapid expansion of the worldwide population has caused an urgent need for the development of new, more environment-conscious, food sources. In this context, algae, such as Euglena, are of interest thanks to their capacity to naturally produce essential nutrients such as proteins and oils commonly found in animals and plant sources. While these processes are currently being investigated, underlying measures affecting growth of Euglena gracilis like hormonal influences and growth stress like nutrient deprivation are poorly understood. From this vantage point, this thesis seeks to understand the role of phytohormones cytokinin (CKs) and abscisic acid (ABA) in complex mechanisms underlying heterotrophic growth of Euglena gracilis under recycled, organic media conditions with no supplementation. Hormone profiles were quantified by HPLC-ESI-MS/MS and compared to culture growth dynamics of pH, weight accumulation, glucose content, cell count and morphology. It was expected that ABA acted as an inhibitory hormone and this was confirmed by its higher levels when CKs where low and vice versa. Contrastingly, it was expected that CKs stimulated growth, in which this was shown not to be the case. Interestingly, it was revealed that both hormone groups increase with increasing recycling. Other key findings include: E. gracilis synthesizes CKs via the tRNA-degradation pathway and is cZ and iP dominated, recycling E. gracilis medium is viable for growth, however, the percentage (25% or less) is crucial to cell viability and markedly no ABA was detected in E. gracilis pellet fractions from recycled media. Therefore, this data revealed that recycled media has a striking influence on physiological aspects of growth and illustrated unique changes in hormone profiles of which could be manipulated to help the food industry. Author Keywords: cytokinin, endogenous hormones, Euglena gracilis, heterotrophic, large scale microalgae cultivation, recycled medium
Problem Solving as a Path to Understanding Mathematics Representations
Little is actually known about how people cognitively process and integrate information when solving complex mathematical problems. In this thesis, eye-tracking was used to examine how people read and integrate information from mathematical symbols and complex formula, with eye fixations being used as a measure of their current focus of attention. Each participant in the studies was presented with a series of stimuli in the form of mathematical problems and their eyes were tracked as they worked through the problem mentally. From these examinations, we were able to demonstrate differences in both the comprehension and problem-solving, with the results suggesting that what information is selected, and how, is responsible for a large portion of success in solving such problems. We were also able to examine how different mathematical representations of the same mathematical object are attended to by students. Author Keywords: eye-tracking, mathematical notation, mathematical representations, problem identification, problem-solving, symbolism
Wastewater Impacts on Freshwater Mussels and Water Quality in a Tributary of the Lower Grand River in Southwestern Ontario, Canada
The main goal of this thesis was to assess the potential impacts of discharges of treated effluent from a small facultative sewage lagoon serving approximately 300 residents of the Mississaugas of the Credit First Nation to freshwater mussel populations in Boston Creek, a small tributary of the lower Grand River. The current resident mussel populations inhabiting Boston Creek were assessed using semi-qualitative visual surveying methods. In addition to various population level observations, other possible point and non-point influences on water quality in Boston Creek were identified. Following this, Lasmigona costata mussels were deployed as biomonitoring organisms alongside passive samplers during the October 2017 lagoon discharge period. Time weighted average (TWA) concentrations of select Contaminants of Emerging Concern (CECs) and Polycyclic Aromatic Hydrocarbons (PAHs) were estimated from levels of these compounds accumulated on passive samplers to understand the influence of wastewater on water quality in Boston Creek. Finally, mussel tissues were analyzed for various biomarkers of exposure to contaminants. Population surveys indicated that Boston Creek supports a plentiful and diverse community of freshwater mussels and may be a refuge for the Species of Special Concern, Villosa iris. Passive sampling revealed that most PAHs measured were present at concentrations below detection limits, while CECs were typically detected at relatively low concentrations (ng/L) directly downstream of the lagoon discharge. Biomarker responses detected in Lasmigona costata generally could not be attributed to exposure to the lagoon effluent but these data may indicate response to other point and non-point sources of pollution that could be affecting resident freshwater mussel populations in Boston Creek. The mussels surveyed in Boston Creek may be displaying community level effects of exposure to other sources of pollution in the area. The results of this thesis will help in establishing water quality guidelines in the lower Grand River watershed that will assist in the recovery strategy for freshwater mussel species at risk in Ontario. Author Keywords: Biomarkers, Biomonitoring, CECs, First Nations, Freshwater Mussels, SAR
Potential for Greenhouse Gas Emissions from Sediments of Agricultural Streams and Lake Erie
This thesis examines how dissolved organic matter quantity and quality and nutrients influence the flux potential of greenhouse gases (GHG) from sediments collected from streams across southern Ontario as well as Lake Erie. Sediments were collected and incubated in a laboratory setting where headspace gases and interstitial waters were analyzed. Results demonstrated that nutrients (dissolved organic carbon (DOC), total dissolved phosphorous (TDP) and total dissolved nitrogen (TDN)) were commonly significant predictors of CO2, CH4, and N2O fluxes, but spatial discrepancies were observed for the significance of DOM quality and sedimentary characteristics. Land use was not found to be directly related to gas flux potential. Different relationships were observed between the streams and lake, and between the basins of Lake Erie. Overall, results from this study suggest that sediments from freshwater systems have the potential to be sources of GHG, the degree of which depends on nutrient concentrations and DOM structure from watershed inputs. Author Keywords: dissolved organic matter, greenhouse gases, Lake Erie, nutrients, sediment, streams
Disease ecology of ophidiomycosis in free-ranging snakes
Ophidiomycosis (snake fungal disease) is caused by the pathogen Ophidiomyces ophiodiicola. Infected snakes exhibit dermal lesions, occasional systemic infections, and, in some cases, mortality. We studied snakes at Rondeau Provincial Park, Ontario, Canada, to explore whether ophidiomycosis develops during brumation or year-round. Throughout their active season, we quantified the prevalence of clinical signs of the disease on snakes and conducted qPCR of skin swabs to determine the prevalence of O. ophiodiicola on snakes. Prevalence of O. ophiodiicola and disease symptoms were highest on eastern foxsnakes (Pantherophis vulpinus) and very rare on other snake species. In P. vulpinus, pathogen and clinical sign prevalence was highest, directly after emergence from overwintering, with the majority of P. vulpinus being able to resolve clinical signs of ophidiomycosis by the return of winter. When we analyzed the survivorship of P. vulpinus we determined that the likelihood of a snake dying with ophidiomycosis is similar to a snake dying without ophidiomycosis. Given that P. vulpinus were the most affected species at our study site, ophidiomycosis does not appear to pose an imminent threat to our study population of P. vulpinus under current conditions. Author Keywords: Eastern Foxsnake, Fitness, Ophidiomycosis, Pantherophis vulpinus, Seasonal trends, Snake fungal disease
Effects of wood ash addition on soil chemical properties and sugar maple (Acer saccharum, Marsh.) seedling growth in two northern hardwood forest sites in central Ontario
One possible solution to acidification and losses of base cations in central Ontario forest soils may be the application of wood ash. Wood ash is generally high in pH and contains large amounts of calcium (Ca) and other nutrients essential for ecosystem health, however it also contains trace metals. Understanding the chemistry of soils following ash application to forests is crucial for future policy recommendations and remediation efforts. In this study, soil and soil water chemistry was measured at two acidic forest sites in central Ontario. Sugar maple (Acer saccharum, Marsh.) seedling growth and chemistry, as well as understory vegetation composition, were also measured. At site one, plots (2 m x 2 m) were established with sugar maple, white pine (Pinus strobus L.) and yellow birch (Betula alleghaniensis Britt.) residential wood ash treatments and applied at rates of 0 and 6 Mg ha-1. The effects of residential wood ash on soil and understory vegetation were measured three- and 12-months following ash addition. At site two, plots (5 m x 5 m) were established with both fly and bottom industrial grade bark ash treatments of 0, 4 and 8 Mg ha-1 (n=4), and tension lysimeters were positioned in each plot at 30, 50, and 100 cm depths. The effects of industrial grade wood ash on soil, soil water and understory vegetation were measured four years following ash addition. Metal concentrations in the ashes were generally low but were higher in the fly ash and yellow birch ash types. At site one, significant increase in soil pH, and Ca and magnesium (Mg) concentrations were observed after three months, however changes varied by treatment. Some metal concentrations increased in the upper organic horizons, but metals were likely immobilized in the soil due to increases in soil pH, electrical conductivity (EC) and high organic matter content of the soil. After one year, changes to metal concentrations in soils could be seen in mineral horizons, and a few metals (aluminum (Al), zinc (Zn), copper (Cu), chromium (Cr), strontium (Sr)) increased in treatment plots. At site two, the effects of industrial-grade bark ashes on soil pH could still be seen after four years and soil water metal concentrations were not elevated relative to controls. Changes to understory vegetation composition following ash application were observed, but ash addition had no significant effect on sugar maple seedling growth (root:shoot ratio) and did not lead to significant increases in foliar metal concentrations. There were significant differences in root chemistry, suggesting metal translocation and uptake could be restricted. Mass balance estimates indicate that the organic horizon is a sink for all metals and simulated drought in this horizon led to a decrease in soil pH and increase in soil water metal concentration, but this occurred in all treatments including control. These results suggest that application of industrial and residential wood ash in moderate doses with trace metal concentrations below or near regulatory limits will increase soil pH and base cation concentrations, as well as increase seedling tissue nutrient concentrations in northern hardwood forest soils. However, depending on the parent material of the ash, increased metal availability can also occur. Author Keywords: Acer saccharum, calcium decline, forest soil amendment, Haliburton Forest and Wildlife Reserve, heavy metal, wood ash
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
Framework for Testing Time Series Interpolators
The spectrum of a given time series is a characteristic function describing its frequency properties. Spectrum estimation methods require time series data to be contiguous in order for robust estimators to retain their performance. This poses a fundamental challenge, especially when considering real-world scientific data that is often plagued by missing values, and/or irregularly recorded measurements. One area of research devoted to this problem seeks to repair the original time series through interpolation. There are several algorithms that have proven successful for the interpolation of considerably large gaps of missing data, but most are only valid for use on stationary time series: processes whose statistical properties are time-invariant, which is not a common property of real-world data. The Hybrid Wiener interpolator is a method that was designed for repairing nonstationary data, rendering it suitable for spectrum estimation. This thesis work presents a computational framework designed for conducting systematic testing on the statistical performance of this method in light of changes to gap structure and departures from the stationarity assumption. A comprehensive audit of the Hybrid Wiener Interpolator against other state-of-the art algorithms will also be explored. Author Keywords: applied statistics, hybrid wiener interpolator, imputation, interpolation, R statistical software, time series

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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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