English

The predator vs. prey dynamic is an omnipresent factor in ecological systems that may drive changes in life history patterns in prey animals through behavioural, morphological, and physiological changes. Predation risk can have profound effects on the life history events of an animal, and is influenced by the neuroendocrine stress response. Activation of the hypothalamic-pituitary-adrenal/interrenal axis, and the induction of stress hormones (e.g., corticosterone (CORT)) have been shown to mediate the onset of inducible anti-predator defensive traits including increased tail-depth, and reduced activity. The predator-prey relationship between dragonfly nymphs and tadpoles can be a powerful model system for understanding mechanisms that facilitate changes in the stress response in accordance with altered severity of risk. It has been well demonstrated early in tadpole ontogeny that increased corticosterone (CORT) levels, observed within three weeks of predator exposure, are correlated with increased tail depth morphology. However, the reactivity of the stress response in relation to the growth modulation in developing prey has yet to be fully explored. Accordingly, this thesis assessed the stress and growth response processes in tadpoles that were continuously exposed to perceived predation risk later in ontogeny. Continuous exposure of prey to predation risk for three weeks significantly increased CORT levels, and tail depth. However, tadpoles exposed to six weeks of predation risk acclimated to the presence of the predator, which was observed as a significant reduction of stressor-induced CORT levels. In addition, although increased tail depth has been attributed to predator defense, predator-naïve tadpoles began to display similar tail depth morphology as treated tadpoles at the six week time point. Thus, this thesis suggests that the stress response in lower vertebrate systems (e.g., tadpoles) may operate in a similarly complex manner to that observed in higher vertebrates (e.g., rats), for which severity of risk associated with the stressor aids in defining activity of the stress response. Moreover, the lack of morphological difference between treatments among tadpoles exposed later in ontogeny suggests that the mechanisms for inducing defenses are normal morphological traits in the development of the animal. This thesis paves the way for future research to elucidate the relationship between the neuroendocrine stress response and hormonal pathways involved in growth modulation in the presence of environmental pressures.

Author Keywords: Acclimation, Corticosterone, Growth Modulation, Predation Risk, R. pipiens, Tadpole

(MRC) in central Ontario was carried out to determine the range and spatial distribution of soil Ca weathering rates, and investigate the relationships between lake Ca and soil and catchment attributes. The MRC is acid-sensitive, and has a long history of impacts from industrial emission sources in Ontario and the United States. Small headwater catchments were sampled for soil and landscape attributes (e.g. elevation, slope, catchment area) at 84 sites. Soil Ca weathering rates, estimated with the PROFILE model, were low throughout the region (average: 188 eq/(ha·yr)) compared to global averages, and lower than Ca deposition (average: 292 eq/(ha·yr)). Multiple linear regression models of lake Ca (n= 306) were dominated by landscape variables such as elevation, which suggests that on a regional scale, landscape variables are better predictors of lake Ca than catchment soil variables.

Author Keywords: Calcium, Lakes, Regional assessment, Regression, Soils, Weathering

Soil mineralizable nitrogen (N) is the main component of soil N supply in humid temperate regions and should be considered in N fertilizer recommendations. The objectives of this study were to determine the potentially mineralizable N parameters, and improve N fertilizer recommendations by evaluating a suite of soil N tests in southwestern Ontario. The study was conducted over the 2013 and 2014 growing seasons using 19 field sites across southwestern Ontario. The average potentially mineralizable N (N0) and readily mineralizable N (Pool I) were 147 mg kg-1 and 42 mg kg-1, respectively. Pool I was the only soil N test that successfully predicted RY in 2013. The PPNT and water soluble N (WSN) concentration (0-30cm depth) at planting were the best predictors of fertilizer N requirement when combing data from 2013 and 2014. When soils were categorized based on soil texture, the relationships also improved. Our findings suggest that N fertilizer recommendations for grain corn can be improved, however, further field validations are required.

Author Keywords: corn, nitrogen, nitrogen mineralization, soil nitrogen supply, soil N test, southwestern Ontario

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

Based on an endogenous hormone study, three cytokinin type phytohormones; benzyladenine (BA), trans-zeatin (tZ) and methylthiol trans-zeatin (MeSZ), as well as abscisic acid (ABA) were exogenously added at three concentrations (10-7, 10-6 and 10-5 M) to cultures of Chlorella vulgaris in an attempt to alter growth rate, total lipid and fatty acid yields and fatty acid profile. Growth stimulation was highest at 10-6 M for BA, MeSZ and ABA and 10-5 M for tZ. All treatments caused changes in total lipid and fatty acid content, with BA causing an increase to lipid content. The most significant change in the fatty acid profile was observed with the addition of MeSZ at 10-7 and 10-6 M causing increases of 204% and 457% in linolenic acid respectively above the control. These results are novel and potentially highly impactful, as MeSZ has never been added exogenously to algae and may be used to stimulate overproduction of linolenic acid for pharmaceutical or industrial purposes.

Author Keywords: Abscisic Acid, Chlorella vulgaris, Cytokinin, Fatty acid, Linolenic Acid, Methylthiol trans-Zeatin

This study examines the influence of dissolved organic matter (DOM) on dissolved vanadium (V) speciation in the Churchill River and Great Slave Lake using diffusive gradients in thin film (DGT). Vanadium is commonly found in natural environments such as rivers, lakes and oceans. It regulates normal cell growth, but in excessive amounts, it can have toxic effects on human and aquatic organisms. The use of in situ, time integrated DGT devices allows to better (1) monitor the most bioavailable fraction of V, the DGT-labile V, in Arctic Rivers and (2) assess the influence of DOM on dissolved V speciation. Higher DGT-labile V was found in the the central regions of the Mackenzie River (MR), with an average of 7.7 ± 2.3 nM, likely due to sediment leaching and permafrost thawing. The Churchill River and Great Slave Lake (GSL) showed lower DGT-labile V levels (2.2 ± 1.6 nM and 3.6 ± 2.7 nM, respectively), compared to central regions in MR. The CR DGT-labile V concentrations was positively correlated to protein-like DOM concentration and abundance (r = 0.3, p < 0.05). The data collected from this study will help in developing new strategies regarding environmental health and impact assessments of environmentally hazardous waste that consist of potentially high levels of toxic vanadium species. Developments in the use of DGT devices as a sampling method will also aid in future studies involved in analyzing environmental health and specifically dissolved V species in natural waters.

Author Keywords: diffusive gradients in thin-films, dissolved organic matter, fluorescence, mass spectrometry, UV-Vis, vanadium

Thermoplastic poly(ester urethane)s (TPEU)s derived from vegetable oils possess inferior physical properties compared to their entirely petroleum-based counterparts due to the structural limitations and lower reactivity of the precursor lipid-derived monomers. The present work shows that high molecular weight of TPEUs with enhanced performance can be obtained from lipid-derived monomers via (i) the synthesis of polyester diols with controlled molecular weights, (ii) the tuning of the functional group stoichiometry of the polyester diols and the diisocyanate during polymerization, (iii) the degree of polymerization (iv) the control of the hard segment hydrogen bond density and distribution via the use of a chain extender and (v) different polymerization protocols.

Solvent-resistant TPEUs with high molecular weight displaying polyethylene-like behavior and controlled polyester and urethane segment phase separation were obtained. Structure-property investigations revealed that the thermal transition temperatures and tensile properties increased and eventually plateaued with increasing molecular weight. Novel segmented TPEUs possessed high phase separation and showed elastomeric properties such as low modulus and high elongation analogous to rubber. The response of the structurally optimized TPEUs to environmental degradation was also established by subjecting the TPEUs to hydrothermal ageing. TPEUs exhibited thermal and mechanical properties that were comparable to commercially available entirely petroleum-based counterparts, and that could be tuned in order to achieve enhanced physical properties and controlled degradability.

Author Keywords: Hydrothermal degradation, Molecular weight control, Polyester diols, Renewable resources, Structure-property relationships, Thermoplastic poly(ester urethane)s

This study assesses the ability of a unicellular protist, Euglena gracilis, to remove Cu and Ni from solution in mono- and bi-metallic systems. Living Euglena cells and non-living Euglena biomass were examined for their capacity to sorb metal ions. Adsorption isotherms were used in batch systems to describe the kinetic and equilibrium characteristics of metal removal. In living systems results indicate that the sorption reaction occurs quickly (<30 min) in both Cu (II) and Ni (II) mono-metallic systems and adsorption follows a pseudo-second order kinetics model for both metals. Sorption capacity and intensity was greater for Cu than Ni (p < 0.05) and were described by the Freundlich model. In bi-metallic systems sorption of both metals appears equivalent. In non-living systems sorption occurred quickly (10-30 min) and both Cu and Ni equilibrium uptake increased with a concurrent increase of initial metal concentrations. The pseudo-first-order model was applied to the kinetic data and the Langmuir and Freundlich models effectively described single-metal systems. The biosorption capacity of Cu (II) and) was 3x times greater than that of Ni (II). Sorption of one metal in the presence of relatively high concentrations of the other metal was supressed. Generally, it was found that living Euglena remove Cu and Ni more efficiently than non-living Euglena biomass in both mono- and bi-metallic systems. It is anticipated that this work should contribute to the identification of baseline uptake parameters and capacities for Cu and Ni by Euglena as well as to the increasing amount of research investigating sustainable bioremediation.

Author Keywords: accumulation, biosorption, Cu, Euglena gracilis, kinetics, Ni

On the first page of the much read, Camera Lucida, Roland Barthes reveals his motive: "I was overcome by an "ontological" desire: I wanted to learn at all costs what Photography was "in itself," by what essential feature it was to be distinguished from the community of images." The impetus of this thesis might be called a Barthesian desire to learn what distinguishes digital photographic images from all other photographic images. Throughout, I ask: what is a digital image? The first exploratory turn reflects upon photographs and touch. While photographs are objects that are both touched and touching, digital images are inscrutable data assemblages that resist

touch and are predisposed to speed. Digital images cannot be touched, yet are responsive to touch. Through the mediating magic of touch sensitive glass, we command digital images to move. Chapter two considers prevailing late twentieth century theory on the digital photograph that claims the eclipse of film by digital imaging will render [digital] photographs totally unreliable documents. The results have been surprising; although suspicion about digital image bodies has crept into the cultural psychological fabric, I argue that we still believe in the basic veracity of [digital] photographic images. Finally, I turn my attention to the objecthood of digital imageobjects in a discussion of the widely unacknowledged materiality of data. Digital image-objects—those speedy, untouchable, dubious, things—are heavy. The weight of their bodies moving in the vast—unseen—global technological infrastructure is the burden of my final reflection.

Author Keywords: death of film, digital materiality, digital photographic realism, ontology of the image, philosophy of photography, photography after photography

Sustainable development is normative - making decisions in the present that construct the experience of place for the future. It is primarily driven by global measures developed to meet the needs of the present while ensuring future generations can meet their own needs. These measures attempt to balance economic prosperity, social justice, and environmental stewardship in many nations. This attempt to balance a plurality of outcomes creates socio-political tensions in choosing between alternatives. These barriers and tensions are characterized through the neoclassical vision of: economics as a science, utility maximization, and alienation of people. This thesis explores the lived experience of community leaders in Peterborough, Ontario as they navigate a contentious and current debate of where to relocate a casino in the region. The results focus on the tension experienced by community leaders as they seek to balance elements of care, while preserving neoclassical values of growth, individualism, freedom of choice, and interconnectedness. The thesis concludes with a model that works towards an understanding of the role of lived experience in economic development decision-making in rurally situated small cities, and recommendations for further research and policy recommendations.

Author Keywords: economic development, governance, lived experience, small city, sustainable development, vision