Graduate Theses & Dissertations

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effects of parasitism on consumer-driven nutrient recycling
Daphnia are keystone consumers in many pelagic ecosystems because of their central role in nutrient cycling. Daphnia are also frequently infected, and the parasites causing these infections may rival their hosts in their ability to regulate ecosystem processes. Therefore, parasitic exploitation of Daphnia may alter nutrient cycling in pelagic systems. This thesis integrates existing knowledge regarding the exploitation of Daphnia magna by 2 endoparasites to predict parasite-induced changes in the nutrient cycling of infected hosts and ecosystems. In chapter 1, I I contextualizing the integration of these themes by reviewing the development of the fields of elemental stoichiometry and parasitology. In chapter 2, we show how the bacterial parasite, Pasteuria ramosa, increased the nitrogen (N) and phosphorus (P) release rates of D. magna fed P-poor diets. We used a mass-balance nutrient release model to show that parasite-induced changes in host nutrient accumulation rates and diet-specific changes in host ingestion rates were responsible for the accelerated nutrient release rates that we observed. In chapter 3, we extended our examination of the nutrient mass balance of infected D. magna to include another parasite, the microsporidian H. tvaerminnensis. We found differences in the effects of these two parasites on host nutrient use as well as support for the hypothesis that parasite-induced changes in Daphnia N release are caused by the effects of infection on Daphnia fecundity. In chapter 4, we examined the relationship between P concentrations and the presence and prevalence of H. tvaerminnensis in rock pools along the Baltic Sea. We found that particulate P concentrations were negatively associated with the prevalence of this parasite, a result that is consistent with the increase in P sequestration of H. tvaerminnensis-infected Daphnia that we observed in chapter 3. I discuss the potential implications of the work presented in chapters 2-4 for other parasite-host systems and ecosystems in chapter 5. Overall, the research presented here suggests that parasite-induced changes in host nutrient use may affect the availability of nutrients in the surrounding environment, and the magnitude of this effect may be linked to parasite-induced reductions in fecundity for many invertebrate hosts. Author Keywords: consumer, ingestion rates, mass-balance, nutrient-recycling, parasitism, phosphorus
methodological framework for the assessment and monitoring of forest degradation under the REDD+ programme based on remote sensing techniques and field data
In this thesis, a methodological framework for the assessment and monitoring of forest degradation based on remote sensing techniques and field data, as part of the REDD+ programme, is presented. The framework intends to support the implementation of a national Monitoring, Verification and Report (MRV) system in developing countries. The framework proposed an operational definition of forest degradation and a set of indicators, namely Canopy Cover (CC), Aboveground Biomass (AGB) and Net Primary Productivity (NPP), derived from remote sensing data. The applicability of the framework is tested in a sub-deciduous tropical forest in the Southeast of Mexico. The results from the application of the methodological framework showed that the higher rates of forest degradation, 1596-2865 ha·year-1, occur in areas with high population density. Estimations of aboveground biomass in these degraded areas span from 1 to 24 Mg·ha-1, with a rate of carbon fixation ranging from 130 to 246 gC·m2·year. The results also showed that 43 % of the forests of the study area remain with no evident signs of degradation, as detected by the indicators selected, during the period evaluated. The integration of the different elements conforming the methodological framework for the assessment and monitoring of forest degradation enabled the identification of areas that maintain a stable condition and areas that change over the period evaluated. The methodology outlined in this thesis also allows for the identification of the temporal and spatial distributions of forest degradation based on the indicators selected, and it is expected to serve as the basis for operations of the REDD+ programme with the appropriate adaptations to the area in turn. Author Keywords: Forest degradation, Monitoring, REDD+, Remote Sensing, Tropical forest
Size and fluorescence properties of allochthonous dissolved organic matter
Dissolved organic matter (DOM) is a mixture of molecules with dynamic structure and composition that are ubiquitous in aquatic systems. DOM has several important functions in both natural and engineered systems, such as supporting microorganisms, governing the toxicity of metals and other pollutants, and controlling the fate of dissolved carbon. The structure and composition of DOM determine its reactivity, and hence its effectiveness in these ecosystem functions. While the structure, composition, and reactivity of riverine and marine DOM have been previously investigated, those of allochthonous DOM collected prior to exposure to microbes and sunlight have received scant attention. The following dissertation constitutes the first in-depth study of the structure, composition, and reactivity of allochthonous DOM at its point of origin (i.e. leaf leachates, LLDOM), as detected by measuring its size and optical properties. Concomitantly, novel chemometric methods were developed to interpret size-resolved data obtained using asymmetrical flow field-flow fractionation, including spectral deconvolution and the application of machine learning algorithms such as self-organizing maps to fluorescence data using a dataset of more than 1000 fluorescence excitation-emission matrices. The size and fluorescence properties of LLDOM are highly distinct. Indeed, LLDOM was correctly classified as one of 13 species/sources with 92.5% accuracy based on its fluorescence composition, and LLDOM was distinguished from riverine DOM sampled from eight different rivers with 98.3% accuracy. Additionally, both fluorescence and size properties were effective conservative tracers of DOC contribution in pH-controlled mixtures of leaf leachates and riverine DOM over two weeks. However, the structure of LLDOM responded differently to pH changes for leaves/needles from different tree species, and for older needles. Structural changes were non-reversible. Copper-binding strength (log K) differed for the different fluorescent components of DOM in a single allochthonous source by more than an order of magnitude (4.73 compared to 6.11). Biotransformation preferentially removed protein/polyphenol-like fluorescence and altered copper-binding parameters: log K increased from 4.7 to 5.5 for one fluorescent component measured by fluorescence quenching, but decreased from 7.2 to 5.8 for the overall DOM, as measured using voltammetry. The complexing capacity of DOM increased in response to biotransformation for both fluorescent and total DOM. The relationship between fluorescence and size properties was consistent for fresh allochthonous DOM, but differed in aged material. Since the size and fluorescence properties of LLDOM are strikingly different from those of riverine DOM, deeper investigation into transformative pathways and mixing processes is required to elucidate the contribution of riparian plant species to DOM signatures in rivers. Author Keywords: Analytical chemistry, Chemometrics, Dissolved organic matter (DOM), Field-flow fractionation, Fluorescence spectroscopy, Parallel factor analysis (PARAFAC)
Nutrient Metabolism of an Aquatic Invertebrate and its Importance to Ecology
Aquatic consumers frequently face nutritional limitation, caused in part, by imbalances between the nutrients supplied by primary producers and the metabolic demands of the consumers. These nutritional imbalances alter many ecological processes including consumer life-history traits, population dynamics, and food web properties. Given the important ecological role of organismal nutrition, there is a need to have precise and specific indicators of nutritional stress in animals. Despite this need, current methods used to study nutrition are unable to distinguish between different types of nutritional limitation. Here I studied nutritional metabolism in the freshwater zooplankter, Daphnia. A greater understanding of nutritional metabolism would allow for the development of dietary bio-indicators that could improve the study of the nutritional ecology of animal consumers. Specifically, I addressed the question: What affects the biochemical composition of a generalist aquatic consumer? My overall hypothesis was that the quantity and quality of the diet affects the biochemical composition in a nutrient specific manner. To test this hypothesis, I examined various response variables involved in nutrient metabolism such as alkaline phosphatase activity, whole metabolome, and free amino acid composition. For each response variable, I grew Daphnia under various nutritional stressors and determined if responses are nutrient specific or are a general stress response. I found the current method of measuring alkaline phosphatase was not a phosphorus specific indicator, as activity increased in all nutrient stressed treatments. Analyzing the whole metabolome resulted in nutritional stressors being separated in multivariate space, with many identified metabolites being significantly different from nutrient rich Daphnia. Upon further examination the daphnids free amino acids profiles are caused by differences between the supply of amino acids from the algae and the demand within the Daphnia. These differences in supply and demand resulted in the ability to classify the nutritional status of Daphnia with the use of discriminant analysis, a classification multivariate model. In addition to a deeper understanding and advanced knowledge of the physiological changes caused by nutrient limitation, this research has provided strong evidence for the application of nutritional biomarkers/profiles to identified the nutritional status of Daphnia. Author Keywords: Bio-indictor, Ecological stoichiometry, Metabolism, Nutritional limitation, Nutritional status
Anarchist Periodical Press in the United States
This dissertation focuses on the English-language anarchist periodical press in the United States in the 1890s and early 1900s. Each of the three chapters of this dissertation examines one anarchist paper and its coverage of a specific issue. The first chapter focuses on Prison Blossoms, which was started by Alexander Berkman, Carl Nold, and Henry Bauer and written and circulated in the Western Penitentiary of Pennsylvania, and its engagement with Alexander Berkman's attempt to assassinate Henry Clay Frick. The second chapter examines Free Society, a weekly edited primarily by Abraham Isaak, and its contributors' writings on the assassination of President William McKinley by self-described anarchist Leon Czolgosz. Finally, the third chapter focuses on The Demonstrator, specifically its first volume which was edited by James F. Morton Jr. from the intentional community of Home, Washington, and the paper's work in supporting John Turner, the first anarchist targeted for deportation under the Immigration Act of 1903. Drawing upon critical discourse analysis, this dissertation incorporates examination of the context in which these papers were written (particularly the immediate concerns to which the papers' authors responded), the form and generic conventions of the anarchist press, including the approaches of the papers' respective editors, and the arguments advanced by their authors. It pays particular attention to the intertextuality of the anarchist press -- the ways in which those writing in anarchist papers addressed one another both within and across periodicals, generating anarchist thought through conversation and debate and enacting their anarchist ideals in the practice of publishing. This dissertation demonstrates that the anarchist periodical press, an element of anarchist history that has received little attention, offers important insights: it details how anarchists immediately responded to important issues of their time, and reveals the ways in which the emergence of anarchism was itself a collective effort, emerging from conversation, debate, and disagreement about how best to create radical change and what that change should look like. Author Keywords: anarchism, anarchist periodicals, critical discourse analysis, Free Society, Prison Blossoms, The Demonstrator
Elemental Variation in Daphnia
Environmental variation can affect consumer trait expression and alter ecological and evolutionary dynamics in natural populations. However, although dietary nutrient content can vary by an order of magnitude in natural ecosystems, intra-specific differences in consumer responses to food quality have not been thoroughly investigated. Therefore, the purpose of my dissertation was to examine the influence of dietary nutrition and other environmental factors on consumer phenotypic variation using the freshwater cladoceran Daphnia. I conducted a series of complementary laboratory and field studies where I examined the effects of dietary phosphorus (P) content and additional biological/environmental variables (multi-elemental limitation, genetic variation, and temperature) on daphnid life-history, biochemistry, body elemental composition, and population growth. In general, phenotypic expression within a species varied significantly in response to all experimental variables, but the relative influence of each was highly context dependent. In my first chapter, I found that dietary P content and environmental calcium (Ca) concentrations both altered Daphnia body Ca:P ratios and growth rates of individuals and affected intrinsic rates of increase at the population level. However, food quality appeared to have a much larger effect on trait expression, and body Ca:P ratios were highly sensitive to other forms of dietary nutrient limitation. Next, I documented significant quantitative genetic variation and phenotypic plasticity in daphnid P content, growth, and P use efficiency of field collected animals grown across dietary P gradients. Trait expression was also influenced by genotype X diet interactions suggesting that consumer responses to dietary nutrient limitation can be heritable and may be adaptive in different nutrient environments. Finally, I found that temperature appeared to override food quality effects and decouple P metabolism in natural Daphnia populations, but total biomass production was affected by both dietary P content and temperature, depending on the nutrient content of the lake. Overall, my dissertation shows that consumer responses to nutrient limitation can vary significantly within a species and that changes in trait expression may be modified by other environmental variables. These results should be incorporated into existing stoichiometric models and used to investigate the eco-evolutionary consequences of consumer phenotypic variation in response to nutritional stress. Author Keywords: ecological stoichiometry, evolution, life-history, nutrient limitation, nutrient metabolism, zooplankton
Carbon Exchange along a Natural Gradient of Deciduous Shrub Coverage in the Low-Arctic
Arctic terrestrial ecosystems have experienced substantial structural and compositional changes in response to warming climate in recent decades, especially the expansion of shrub species in Arctic tundra. Climatic and vegetation changes could feedback to the global climate by changing the carbon balance of Arctic tundra. The objective of this thesis was to investigate the influence of increased shrub coverage on carbon exchange processes between atmosphere and the Arctic tundra ecosystem. In this study a space-for-time substitution was used, referred to as a shrub expansion “chronosequence”, with three sites along a natural gradient of deciduous shrub coverage in the Canadian low Arctic. Leaf-level photosynthetic capacity (Amax) of dominating birch shrub Betula glandulosa (Michx.) was significantly higher (P<0.05) at the site where shrubs were more abundant and taller than at the other sites. For all sites, mean Amax in 2014 was significantly lower than in 2013, in part potentially due to differences in precipitation distribution. Bulk soil respiration (RS) rate was significantly higher (P<0.05) at the site with more shrubs compared with the other sites. The differences in RS across sites appeared to be driven by differences in soil physiochemical properties, such as soil nitrogen and soil bulk density rather than soil microclimate factors (e.g. soil temperature, moisture). The three sites were either annual CO2 sources (NEP<0) to the atmosphere or CO2 neutral, with strongest annual CO2 sources (-44.1±7.0 g C m-2) at the site with most shrubs. Overall this study suggests that shrubs tundra carbon balance will change with shrub expansion and that shrub ecosystems in the Arctic currently act as annual carbon sources or neutral to the atmospheric CO2 and further shrub expansion might strengthen the CO2 emissions, causing a positive feedback to the warming climate. Author Keywords: arctic tundra, carbon exchange, climate change, photosynthetic capacity, shrub expansion, soil respiration
Identification and Quantification of Organic Selenium Species Produced by Microbiological Activity in Freshwater Environments
Despite being an essential nutrient at trace levels, selenium can be devastating to aquatic environments when present in excess. There is no apparent correlation between total aqueous selenium concentrations and observed toxic effects because bioaccumulation varies over several orders of magnitude depending on the chemical species of selenium and the biological species present in the lowest trophic level of the aquatic food chain. Despite being used in toxicity models due to its high bioavailability, free selenomethionine had not been found previously in the environment outside of a biological entity. Here, it is confirmed that selenomethionine is produced during the biological treatment of selenium-contaminated wastewater, and released in the effluent along with other discrete organic selenium species, including selenomethionine oxide. This identification followed the development of a rigorous preconcentration and cleanup procedure, allowing for the analysis of these organic selenium species in high-ionic strength matrices. A newly optimized anion-exchange chromatographic separation was coupled to inductively-coupled plasma mass spectrometry for the simultaneous quantification of these organic selenium species along with the more ubiquitous selenium oxyanions, selenite and selenate. This separation method was also coupled to electrospray tandem mass spectrometry for structural confirmation of selenomethionine and selenomethionine oxide. High resolution orbitrap mass spectrometry was used to identify another oxidation product of selenomethionine – a cyclic species which was tentatively identified, by coelution, in a selenium-contaminated river water sample. The production and release of selenomethionine, selenomethionine oxide, Se-(methyl) selenocysteine, and methyl selenic acid were observed for various laboratory algal cultures. Once the presence of free selenomethionine in a water system was confirmed, factors affecting its uptake into algal cultures were examined. The uptake of selenomethionine into Scenedesmus obliquus was noted to be significantly higher under low nitrate conditions, where it was incorporated into selenium-containing proteins more readily than at higher nitrate conditions where other metabolites were produced. With the increasing popularity of biological treatment systems for the remediation of selenium-contaminated waters, these observations, combined with existing knowledge, could be used to make predictions regarding the potential toxicity of selenium in various environmental scenarios. Author Keywords: bioremediation, electrospray mass spectrometry, inductively-coupled plasma mass spectrometry, selenium, selenoamino acids, selenomethionine
Eros noir
The dissertation explores the aesthetic anthropology of Georges Bataille and his collaborators in the Collège de Sociologie, a distinguished group of intellectuals including Roger Caillois, Michel Leiris, Pierre Klossowski, and Walter Benjamin among others. At the dissertation's outset the role, influence, discovery and indeed invention of the Marquis de Sade as the almost mythic prefiguring for so much French aesthetic thought in the period beginning after World War One and up until even the present day is advanced. Before Freud in Vienna, Sade in Paris: the central thematic axis of the following addresses Eros noir, a term for reflecting on the danger and violence of sexuality that Freud theorizes with the "death drive." The deconstruction of the nude as an object and form in particular in the artwork of Hans Bellmer and the writing and art of Pierre Klossowski comprises the latter two chapters of the dissertation, which provides examples of perversion through the study of simulacra and phantasms. The thwarted pursuit of community in the vacated space of Nietzsche's death of a God is a persistent leitmotif of the following in the account it offers of the thought of Georges Bataille and other members of the Collège de Sociologie. Eros noir, at the fatal cusp between ascendant manifest sex and a latent diminished Christianity, underwrites much of the French intellectual contribution to the symbology of cultural modernism. Author Keywords: Bataille, Georges, 1897-1962, Collège de Sociologie, Eroticism, Sade, marquis de, 1740-1814, Surrealism, The Uncanny
Know*ledge Constellations and Re*constellating
The purpose of this study was to explore the educational implications of a clearer understanding of the practice of using multiple, including Indigenous, knowledges when finding solutions to place-based environmental issues. The impetus for my research came from a growing sense of urgency to address environmental issues within both Indigenous and non-Indigenous communities. Some have argued that communities will be most successful in understanding and resolving such issues if ways can be found to work with different knowledges. However, the practice of bringing together multiple knowledges is not yet consistently effective. At the same time, there is a recognised need for individuals who are able to use different knowledges to address urgent environmental concerns. Unfortunately, there is minimal programming advice based on the perspective of individual practitioners available to guide post-secondary institutions wishing to meet this need. This lead to my first two research questions: What are the key principles and concepts in a narrative describing how individual practitioners think about using knowledges when finding solutions to place-based environmental issues? and What are the implications of this understanding for teaching and learning, especially in post-secondary Indigenous-and-Environmental education? In my project, I used a relational research approach that led to a third question: How is a complexity-inspired interpretive approach suitable for exploring these questions? I had coherent conversations with sixteen practitioners who were deliberately using multiple, including Indigenous, knowledges to find solutions to place-based environmental issues. Practitioners and I co-created a Know*ledge Constellation Story to describe how they think about using knowledges in their work. In a group coherent conversation with five educators who were familiar with Indigenous-and-Environmental education, we explored the educational implications of this story. Together, we finalised a Teaching-Learning Story of Re*constellating and identified ways to prepare students to practice re*constellating, including teaching strategies and program considerations. The Know*ledge Constellation Story and the Teaching-Learning Story of Re*constellating will inform post-secondary Indigenous-and-Environmental education. Graduates from such programs will be better prepared to engage with communities to address environmental concerns, meet legislative and policy requirements, and support research efforts that would benefit from a clearer understanding of the practice of re*constellating. Author Keywords: Complexity-Inspired Interpretive Approach, Conditions of Emergence, Indigenous-and-Environmental Education, Know*ledge Constellations, Principles of Re*constellating, Teaching and Learning
Assessing the Potential for Contamination of Lakes from Upwelling of Arsenic-Laden Groundwater Through Sediments
A bedrock fracture hosting arsenic (As) contaminated groundwater was suspected to be transported to Ramsey Lake, a drinking water resource for more than 50,000 residents of Sudbury, Ontario. A high resolution, spatial, water quality mapping technique using an underwater towed vehicle (UTV) was used to identify sources of upwelling groundwater into lake water and localize the upwelling As contaminated groundwater vent site. The top 7 cm of lake sediments (in-situ) at this vent site were observed to adsorb 93 % of the dissolved As, thus inhibiting lake water quality degradation from this contaminant source. Sediment samples from this location were used in laboratory experiments to assess the potential for this system to become a source of As contamination to Ramsey Lake water quality and elucidate As(III) fractionation, transformation and redistribution rates and processes during aging. Arsenic speciation is important because As(III) has been shown to be more toxic than As(V). To accomplish this a sequential extraction procedure (SEP) that maintains As(III) and As(V) speciation in (sub)oxic sediments and soils was validated for the operationally defined fractions: easily exchangeable, strongly sorbed, amorphous Fe oxide bound, crystalline Fe oxide bound, and the residual fraction for total As because the characteristics of the reagents required to extract the final fraction do not maintain As species. Batch reaction experiments using sediment spiked with As(III) or As(V) and aged for up to 32 d were sequentially extracted and analysed for As(III) and As(V). Consecutive reaction models illustrate As(III) is first adsorbed to the sediment then oxidized to As(V). Fractionation analyses show As(III) most rapidly adsorbs to the easily exchangeable fraction where it is oxidized and redistributes to the strongly sorbed and amorphous Fe oxide bound fractions. Oxidation of As(III) adsorbed to the amorphous and crystalline Fe oxide bound fractions is less efficient and possibly inhibited. Select samples amended with goethite provide evidence supporting Mn(II) oxidation is catalyzed by the goethite surface, thus increasing As(III) oxidation by Mn(III/IV) complexed with the strongly sorbed fraction. Although As immobilization through groundwater sediment interactions may be inhibited by increased ion activity, particularly phosphate or lake eutrophication, this threat in Ramsey Lake is likely low. Author Keywords: arsenic, fractionation, modelling, redistribution, speciation, water quality mapping
Politics of Memory
In dialogue with the critical scholarship on war and remembrance, my research deals with the construction, contestation and negotiation of collective memory in contemporary Vietnam with a focus on commemorations devoted to dead soldiers. Utilizing the methodologies of cultural studies and ethnography, this research seeks to comprehend the politics of memory which characterize collective memory as a social phenomenon whose meanings, interpretations and forms are variedly constructed from a certain social group to the next. Empirically, in this research, constitutive elements of Vietnamese postwar memoryscapes including the hero-centered discourse sanctioned by the Communist Party and the Socialist state, the family remembrance rooted in religious and kinship mandates and the newly emerged online ecology of memory are examined in their own nature as well as in their complicated intertwinements and constant interactions with each other. Case studies and specific methods of individual interview, participant observation and cultural analysis enable the author to approach and identify a wide range of forms and intersections between official and vernacular practices, between oral and living history and institutionalized and cultural presentations of memory. While considering these issues specifically in the Vietnamese context, my dissertation contributes to the increasing theoretical debates in the field of memory studies by exploring the relation of power and the symbolic struggle within and between different social agents involved. As it emphasizes the dynamic and power of memory, this research furthermore situates the phenomenon of collective memory in its dialogues with a broader cultural political environment of postwar society, which is characterized as a hybrid condition embracing processes of nationalism, modernization and post-socialist transformation. Significantly, during these dialogues, as demonstrated in this research, memory works embrace presentism and future-oriented functions which require any social group who is involved to negotiate and renegotiate its position, and to structure and restructure its power. Last but not least it must construct and reconstruct its own versions of the past. Author Keywords: collective memory, Dead soldiers, postwar society, Socialist Vietnam, the politics of memory, war remembrance

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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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