Graduate Theses & Dissertations

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Absorbance and Fluorescence Characteristics of Dissolved Organic Matter in North Atlantic, Pacific and Arctic Oceans
This thesis was designed to quantify absorbance and fluorescence characteristics of dissolved organic matter (DOM) in North Atlantic, Pacific and Arctic Oceans. DOM was described in water masses of distinct sources and formation pathways as well as in regions where environmental forcings such as deep water upwelling, enhanced biological activity and receipt of freshwater discharge were prevalent. Influence of sea ice on DOM in Beaufort Sea mixed layer (0 to 30 m) seawater was investigated based on sea ice extent as well as freshwater fractions of meteoric (fmw) and sea ice melt water (fsim) calculated from oxygen isotope ratio (δ18O). The effect of DOM exposure to simulated solar radiation was also assessed to determine the resilience of fluorescent fractions of DOM to photodegradation. This research aims to further our ability to trace DOM in marine environments and better understand its transformation pathways and predict its fate as part of the oceanic carbon cycle in a changing climate. Author Keywords: Absorbance, Arctic Ocean, Dissolved organic matter, Fluorescence, Parallel Factor Analysis, Sea Ice
Adaptive Genetic Markers Reveal the Biological Significance and Evolutionary History of Woodland Caribou (Rangifer tarandus caribou) Ecotypes
Migratory and sedentary ecotypes are phenotypic distinctions of woodland caribou. I explored whether I could distinguish between these ecotypes in Manitoba and Ontario using genetic signatures of adaptive differentiation. I anticipated that signatures of selection would indicate genetic structure and permit ecotype assignment of individuals. Cytochrome-b, a functional portion of the mitochondrial genome, was tested for evidence of adaptation using Tajima’s D and by comparing variations in protein physiology. Woodland caribou ecotypes were compared for evidence of contemporary adaptive differentiation in relation to mitochondrial lineages. Trinucleotide repeats were also tested for differential selection between ecotypes and used to assign individuals to genetic clusters. Evidence of adaptive variation in the mitochondrial genome suggests woodland caribou ecotypes of Manitoba and Ontario corresponded with an abundance of functional variation. Woodland caribou ecotypes coincide with genetic clusters, and there is evidence of adaptive differentiation between migratory caribou and certain sedentary populations. Previous studies have not described adaptive variation in caribou using the methods applied in this study. Adaptive differences between caribou ecotypes suggest selection may contribute to the persistence of ecotypes and provides new genetic tools for population assessment. Author Keywords: Adaptation, Cytochrome-B, Ecotype, RANGIFER TARANDUS CARIBOU, Selection, TRINUCLEOTIDE REPEAT
An Assessment of Spatial Trends in the Accumulation of Oil Sands Related Metals in the Clearwater River Valley and Temporal Trends in Six Northern Saskatchewan Lakes
The objective of this thesis was to assess current spatial trends and historic trends in the accumulation of trace metals related to the Athabasca Oil Sands Region (AOSR). The AOSR hosts some of the largest industrial developments in Canada, yet relatively little is known about the transport and fate of trace metal emissions from the region – particularly in the relatively remote areas to the east of the AOSR. Lichens are widely used as biomonitors and are employed in this thesis to assess the range of metals deposition within the Clearwater River and Athabasca River Valleys. Lake sediment cores can retain a historical record of the long-range transport and deposition of metals but can also respond to large regional metal emissions sources. This thesis used lake sediment cores to assess temporal trends in metals accumulation in six road accessible lakes in NW Saskatchewan that are likely to be used by local residents. Results show that metal concentrations (V, Co, Cu, Ni, Pb, Zn, Zr and Cd ) in lichen decline exponentially with distance from the AOSR and approach background levels within a few kilometers . Results from lake sediment cores show that there was no evidence that metal concentrations had increased due to industrial activities in the AOSR. Author Keywords: Air Emissions, Lakes, Lichens, Oil Sands, Saskatchewan, Trace Metals
Analysis and reactions of aqueous selenide and other reduced inorganic selenium compounds under anoxic conditions
Selenide is cited as a geochemically important selenium (Se) species, but it is unknown whether selenide is a stable aqueous ion in natural waters. The feasibility of using anoxic anion exchange chromatography (AEC) coupled to dynamic reaction cell-inductively coupled plasma-mass spectrometry to separate aqueous selenide was investigated with the goal of quantifying this anion to determine its importance in reducing waters. It was possible to qualitatively identify selenide using AEC, but much of the aqueous selenide oxidises to Se0 faster than the separation procedure could be completed. AEC analyses of solutions containing polyselenides produced peaks for unidentified Se compounds, which have been assigned tentative structures Se2O22-, Se2O32-, and Se2O62- based on close matches in retention time to stable S compounds. The results of this work show that aqueous selenide can be qualitatively observed in synthetic solutions using AEC, but it is unknown whether these conditions are relevant to natural waters. Author Keywords: anoxic speciation, polyselenides, selenide, selenium geochemistry, selenium speciation, selenoselenate
Anthropogenic microfibres in background natural environments in Ireland
Microfibres, which are threadlike particles < 5 mm, are the most common type of microplastic reported in the environment. However, few studies have focused on their abundance in background natural environments. This study assessed the abundance of microfibres in rainfall samples (from four precipitation monitoring stations) and across three headwater lake catchments that were in remote, undeveloped areas, away from anthropogenic disturbance and anthropogenic emission sources (i.e., sites were background natural environments). Anthropogenic microfibres were observed in all samples using visual identification methods, with Raman spectroscopy confirming the presence of polyester film and synthetic pigments, e.g., indigo and hostasol green. The estimated annual average atmospheric deposition of microfibres was ~28,800 mf m-2. Meteorological variables, e.g., rain, wind direction, and relative humidity were correlated with the abundance of microfibres. The average abundance of microfibres in headwater lake catchments was 24 mf g-1 in moss, 0.70 mf m-3 in surface trawl, 9,690 mf m-3 in subsurface, 910 mf kg-1 in lake sediment and 576 mf kg-1 in lakeshore sediment. Author Keywords: Atmospheric Deposition, Background Environments, Headwater Lake Catchments, Microfibres, Microplastics, Rainfall
Aquatic Invertebrate Studies from Two Perspectives
Leaf litter decomposition represents a major pathway for nutrient cycling and carbon flow in aquatic ecosystems, and macroinvertebrates play an important role in the processing of this material. To assess the causes of variable leaf breakdown and nutrient fluxes, I measured decomposition rates and the nutrient release ratios of decomposing leaf material across a broad latitudinal gradient in Ontario boreal lakes which varied in nutrients, temperature, and pH. I examined the effects of macroinvertebrates using inclusion and exclusion bags. Generally, leaves decomposed faster in nutrient-rich, warmer lakes. Macroinvertebrates increased decomposition rates but their effects were relatively small compared to regional effects of nutrients and temperature. In addition, we found differential effects of nutrients and temperature on nutrient release ratios, which were partially determined by the release and retention of N and P. These results indicate that changes in these important environmental lake variables could alter decomposition dynamics in Ontario lakes, with implications for nutrient cycling and the storage of this important external carbon source. I studied the biogeography of predaceous diving beetles (Coleoptera: Dytiscidae) in two remote and understudied regions: the Far North of Ontario, and Akimiski Island, Nunavut. I identified 35 species from northern Ontario, including three first provincial records for Ontario, Acilius athabascae Larson (1975), Hygrotus unguicularis (Crotch 1874), and Nebrioporus depressus (Fabricius 1775). I also documented three significant range extensions and six gap-infills for this region. I collected and identified 16 species from Akimiski Island, Nunavut, which include several first time reports for these species for the Nunavut territory. My collections also extend the known ranges of five species into the Hudson Plains Ecozone. This work provides important baseline information on the distribution of diving beetles for these regions. Author Keywords: biodiversity, Boreal Shield, decomposition, Dytiscidae, ecological stoichiometry, macroinvertebrates
Assessing Canada Lynx Dispersal Across an Elevation Barrier
Mountain ranges are often thought to restrict movement of wildlife, yet previous studies evaluating the role of the Rocky Mountains as a dispersal barrier for Canada lynx (Lynx canadensis) have been contradictory. Our study uses neutral microsatellite loci to evaluate the role of the Rocky Mountains as a barrier to gene flow for lynx. Although lynx exhibited low genetic differentiation, we detected a limited effect of the mountains. Furthermore, we inferred the role played by landscape variables in gene flow (genetic differentiation predicted by landscape resistance). Limited gene flow most strongly related to resistance from physical factors (low snow cover and elevation), rather than other topographic and ecological factors (high terrain roughness, low forest cover, low habitat suitability, and geographic distance). Structural connectivity was a relatively poor predictor of functional connectivity. Overall, the Rockies represent an area of reasonably high functional connectivity for lynx, with limited resistance to gene flow. Author Keywords: Canada lynx, connectivity, gene flow, genetic structure, landscape genetics, Rocky mountains
Assessing Connectivity of Protected Area Networks and the Role of Private Lands in the United States
Forestalling biodiversity loss through the establishment of protected areas is a universally accepted conservation strategy, yet despite established guidelines for protected area coverage and placement, much of the world is currently failing to meet its commitments to conservation planning and landscape protection. Calls for the United States to protect more land usually focus on the need for strategic selection of land parcels to bolster protected area coverage and network functionality, but to date there lacks focused research on either the role of private protected areas in conservation planning or the factors affecting individual protected area selection and importance. We determined gaps in conservation planning in the contiguous United States by analyzing the connectivity of protected area networks by state, and assessing the importance of private protected areas in improving linkages in protected area connectivity. We found that all states had low coverage from protected areas (average <8.4% of total land mass), and especially private protected areas (average <1.1% of total land mass), and that the overall contribution of such areas to protected area network connectivity also was low. Terrain ruggedness was identified as the main factor affecting the current location of protected areas, and that protected area spatial layout is a primary influence on landscape connectivity. We conclude that establishment of private protected areas could offer a viable conservation tool for increasing protected area coverage and connectivity, but that current efforts are inadequate to either adequately link existing protected areas or to meet established land protection guidelines. Author Keywords: Aichi Target 11, conservation planning, graph theory, network theory, private conservation, protected areas
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 the population genetic structure of the endangered Cucumber tree (Magnolia acuminata) in southwestern Ontario using nuclear and chloroplast genetic markers.
Magnolia acuminata (Cucumber tree) is the only native Magnolia in Canada, where it is both federally and provincially listed as endangered.Magnolia acuminata in Canada can be found inhabiting pockets of Carolinian forest within Norfolk and Niagara regions of southwestern Ontario. Using a combination of nuclear and chloroplast markers, this study assessed the genetic diversity and differentiation of M. acuminata in Canada, compared to samples from the core distribution of this species across the United States. Analyses revealed evidence of barriers to dispersal and gene flow among Ontario populations, although genetic diversity remains high and is in fact comparable to levels of diversity estimated across the much broader range of M. acuminata in the USA. When examining temporal differences in genetic diversity, our study found that seedlings were far fewer than mature trees in Ontario, and in one site in particular, diversity was lower in seedlings than that of the adult trees. This study raises concern regarding the future viability of M. acuminata in Ontario, and conservation managers should factor in the need to maintain genetic diversity in young trees for the long-term sustainability of M. acuminata in Ontario. Author Keywords: conservation genetics, cpDNA, forest fragmentation, Magnolia acuminata, microsatellites, population genetic structure
Assessment of Potential Threats to Eastern Flowering Dogwood (Cornus florida) in Southern Ontario
In Canada, eastern flowering dogwood (Cornus florida L.) is an endangered tree that occurs only in the Carolinian forest of southern Ontario. Threats to this species include habitat fragmentation and the fungal pathogen dogwood anthracnose (Discula destructiva). I conducted a population genetic analysis using seven nuclear microsatellite markers to determine if fragmented populations are genetically isolated from one another and have low levels of genetic diversity. Genetic comparisons suggest on-going dispersal among sites and relatively high genetic diversity within most sites; however, smaller populations and younger trees were less genetically diverse. I also used linear mixed effects models to assess potential relationships between several ecological variables and the prevalence of dogwood anthracnose. Disease severity was higher in trees on shallow slopes and in larger trees; the latter also had higher likelihood of infection. Insights from this study will be important to incorporate into future management strategies. Author Keywords: Cornus florida, Discula destructiva, dogwood anthracnose, Eastern flowering dogwood, endangered, population genetics
Assessment of an adult lake sturgeon translocation (Acipenser fulvescens) reintroduction effort in a fragmented river system
North American freshwater fishes are declining rapidly due to habitat fragmentation, degradation, and loss. In some cases, translocations can be used to reverse local extirpations by releasing species in suitable habitats that are no longer naturally accessible. Lake sturgeon (Acipenser fulvescens) experienced historical overharvest across their distribution, leading to endangered species listings and subsequent protection and recovery efforts. Despite harvest and habitat protections, many populations do not appear to be recovering, which has been attributed to habitat alteration and fragmentation by dams. In 2002, 51 adult lake sturgeon from the Mattagami River, Ontario, Canada were translocated 340 km upstream to a fragmented 35 km stretch of the river between two hydroelectric generating stations, where sturgeon were considered extirpated. This study assessed the translocation effort using telemetry (movement), demographics and genetic data. Within the first year, a portion of the radio-tagged translocated individuals dispersed out of the release area, and released radio-tagged individuals used different areas than individuals radio-tagged ten years later. Catches of juvenile lake sturgeon have increased over time, with 150 juveniles caught within the duration of this study. The reintroduced population had similar genetic diversity as the source population, with a marked reduction in effective population size (Ne). The results indicate that the reintroduction effort was successful, with evidence of successful spawning and the presence of juvenile lake sturgeon within the reintroduction site. Overall, the results suggest adult translocations may be a useful tool for re-establishing other extirpated lake sturgeon populations. Author Keywords: conservation, endangered species, lake sturgeon, reintroduction, telemetry, translocation

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Format: 2021/10/27