In some systems, including copper niobium, it has been found that as the scale of the two phases decreases, there is an anomalous increase in strength. Mechanisms of this strengthening have been postulated, but a general theory has yet to be developed. A model system to study the co-deformation of fine scale materials was developed and characterized. An aluminum 18.5at.% zinc alloy was selected and discontinuously precipitated to produce 100% transformation and an interlamellar spacing of 240nm.The material was tested using strain rate jump tests to determine the temperature sensitivity, tensile tested to determine work hardening and the temperature sensitivity, wire drawn to study the effect of large plastic deformation and finally tension compression tested to determine internal stresses. The bulk properties of the two phases are well known allowing for a detailed analysis of the composite properties when combined with the mechanical results. The material showed increased strength above the rule of mixture prediction from bulk properties due to a fine scale microstructure . Although the lamellar material had a much higher strength than the rule of mixtures would predict, the overall strength of the alloy did not approach that of more conventional high strength aluminum alloys. The material was found to be temperature and rate dependent, with an increased work hardening rate as the temperature was decreased. Temperature was found to play a key role in the stress partitioning between the two phases. Temperature dependent relaxation processes lowered the stress partitioning between the hard and soft phases as the temperature was increased. Therefore, stress relaxation must be minimized to maximize the strengthening found in fine scale materials.

The response of plants to climate change is among the main questions in ecology and evolution. Faced with changing conditions, populations may respond by adapting, going extinct or migrating. Fine-scale environmental variation offers a unique mosaic to explore these alternatives. In this thesis, I used ecological surveys, field experiments and molecular methods to study the range of possible responses at a very local scale in the alpine dwarf willow Salix herbacea L. Since gene flow may impact the potential for adaptation and migration, I first explored whether phenological divergence driven by snowmelt patterns impacts gene flow. I found that sites with late snowmelt work as sinks of the genetic diversity, as compared to sites with early snowmelt. I also used a combined approach that looked at the selection, heritability and genomic architecture of ecologically-relevant traits, as well as genomic divergence across the snowmelt mosaic. In this way, I was able to understand which genomic regions may relate to phenological, growth and fitness traits, and which regions in the genome harbor genetic variation associated with late- and early- snowmelt sites. I found that most of the genomic divergence driven by snowmelt is novel and is localized in few regions. Also, Salix herbacea has a strong female bias. Sex bias may matter for adaptation to climate change because different sexes of many dioecious species differ in several functions that may fluctuate with changing conditions. I found that the bias is uniform across environments and is already present at seeds and seedlings. A polygenic sex determination system together with transmission distortion may be maintaining the bias. Overall, fast-evolving microhabitat-driven genomic divergence and, at the same time, genetically-based trait variation at a larger scale may play a role for the ability of S. herbacea to persist in diverse and variable conditions. / SNSF Sinergia Salix

In some systems, including copper niobium, it has been found that as the scale of the two phases decreases, there is an anomalous increase in strength. Mechanisms of this strengthening have been postulated, but a general theory has yet to be developed. A model system to study the co-deformation of fine scale materials was developed and characterized. An aluminum 18.5at.% zinc alloy was selected and discontinuously precipitated to produce 100% transformation and an interlamellar spacing of 240nm.The material was tested using strain rate jump tests to determine the temperature sensitivity, tensile tested to determine work hardening and the temperature sensitivity, wire drawn to study the effect of large plastic deformation and finally tension compression tested to determine internal stresses. The bulk properties of the two phases are well known allowing for a detailed analysis of the composite properties when combined with the mechanical results. The material showed increased strength above the rule of mixture prediction from bulk properties due to a fine scale microstructure . Although the lamellar material had a much higher strength than the rule of mixtures would predict, the overall strength of the alloy did not approach that of more conventional high strength aluminum alloys. The material was found to be temperature and rate dependent, with an increased work hardening rate as the temperature was decreased. Temperature was found to play a key role in the stress partitioning between the two phases. Temperature dependent relaxation processes lowered the stress partitioning between the hard and soft phases as the temperature was increased. Therefore, stress relaxation must be minimized to maximize the strengthening found in fine scale materials.

In some systems, including copper niobium, it has been found that as the scale of the two phases decreases, there is an anomalous increase in strength. Mechanisms of this strengthening have been postulated, but a general theory has yet to be developed. A model system to study the co-deformation of fine scale materials was developed and characterized. An aluminum 18.5at.% zinc alloy was selected and discontinuously precipitated to produce 100% transformation and an interlamellar spacing of 240nm.The material was tested using strain rate jump tests to determine the temperature sensitivity, tensile tested to determine work hardening and the temperature sensitivity, wire drawn to study the effect of large plastic deformation and finally tension compression tested to determine internal stresses. The bulk properties of the two phases are well known allowing for a detailed analysis of the composite properties when combined with the mechanical results. The material showed increased strength above the rule of mixture prediction from bulk properties due to a fine scale microstructure . Although the lamellar material had a much higher strength than the rule of mixtures would predict, the overall strength of the alloy did not approach that of more conventional high strength aluminum alloys. The material was found to be temperature and rate dependent, with an increased work hardening rate as the temperature was decreased. Temperature was found to play a key role in the stress partitioning between the two phases. Temperature dependent relaxation processes lowered the stress partitioning between the hard and soft phases as the temperature was increased. Therefore, stress relaxation must be minimized to maximize the strengthening found in fine scale materials. / Applied Science, Faculty of / Materials Engineering, Department of / Graduate

Movement and behavior studies are traditional yet effective ways to understand the biology and ecology of a species. For an endangered species like the whale shark (Rhincodon typus), a comprehensive knowledge of its movement and behavior is particularly critical for successful management and conservation. For this dissertation, acoustic telemetry and biologging tagging studies were carried out at a seasonal whale shark aggregation site near Al Lith in the Saudi Arabian Red Sea. Acoustic telemetry data revealed consistent path usage in a narrow longshore area with patterns in seasonality and diel horizontal movements within a smaller scale. Some individuals specifically concentrated on this path and made non-stop back and forth movements along it. In another dimension, depth use of whale sharks derived from biologgers showed distinct diel patterns. The sharks heavily utilized shallow waters with mixed depth usage consisting of surface swimming and varied types of dives, which explained the data of previous visual surveys. Vertical velocities indicated potential energy expenditure strategies that were further investigated based on acceleration data. Energy expenditure data suggested strategies that fine-tuned foraging efforts to optimize the balance between feeding and foraging. However, while these strategies fit well in the natural habitat, local human impacts could be of great disturbance if not well managed.

<p>Effective conservation and management of top predators requires a comprehensive understanding of their distributions and of the underlying biological and physical processes that affect these distributions. The Mid-Atlantic Bight shelf break system is a dynamic and productive region where at least 32 species of cetaceans have been recorded through various systematic and opportunistic marine mammal surveys from the 1970s through 2012. My dissertation characterizes the spatial distribution and habitat of cetaceans in the Mid-Atlantic Bight shelf break system by utilizing marine mammal line-transect survey data, synoptic multi-frequency active acoustic data, and fine-scale hydrographic data collected during the 2011 summer Atlantic Marine Assessment Program for Protected Species (AMAPPS) survey. Although studies describing cetacean habitat and distributions have been previously conducted in the Mid-Atlantic Bight, my research specifically focuses on the shelf break region to elucidate both the physical and biological processes that influence cetacean distribution patterns within this cetacean hotspot. </p><p>In Chapter One I review biologically important areas for cetaceans in the Atlantic waters of the United States. I describe the study area, the shelf break region of the Mid-Atlantic Bight, in terms of the general oceanography, productivity and biodiversity. According to recent habitat-based cetacean density models, the shelf break region is an area of high cetacean abundance and density, yet little research is directed at understanding the mechanisms that establish this region as a cetacean hotspot. </p><p>In Chapter Two I present the basic physical principles of sound in water and describe the methodology used to categorize opportunistically collected multi-frequency active acoustic data using frequency responses techniques. Frequency response classification methods are usually employed in conjunction with net-tow data, but the logistics of the 2011 AMAPPS survey did not allow for appropriate net-tow data to be collected. Biologically meaningful information can be extracted from acoustic scattering regions by comparing the frequency response curves of acoustic regions to theoretical curves of known scattering models. Using the five frequencies on the EK60 system (18, 38, 70, 120, and 200 kHz), three categories of scatterers were defined: fish-like (with swim bladder), nekton-like (e.g., euphausiids), and plankton-like (e.g., copepods). I also employed a multi-frequency acoustic categorization method using three frequencies (18, 38, and 120 kHz) that has been used in the Gulf of Maine and Georges Bank which is based the presence or absence of volume backscatter above a threshold. This method is more objective than the comparison of frequency response curves because it uses an established backscatter value for the threshold. By removing all data below the threshold, only strong scattering information is retained.</p><p>In Chapter Three I analyze the distribution of the categorized acoustic regions of interest during the daytime cross shelf transects. Over all transects, plankton-like acoustic regions of interest were detected most frequently, followed by fish-like acoustic regions and then nekton-like acoustic regions. Plankton-like detections were the only significantly different acoustic detections per kilometer, although nekton-like detections were only slightly not significant. Using the threshold categorization method by Jech and Michaels (2006) provides a more conservative and discrete detection of acoustic scatterers and allows me to retrieve backscatter values along transects in areas that have been categorized. This provides continuous data values that can be integrated at discrete spatial increments for wavelet analysis. Wavelet analysis indicates significant spatial scales of interest for fish-like and nekton-like acoustic backscatter range from one to four kilometers and vary among transects. </p><p>In Chapter Four I analyze the fine scale distribution of cetaceans in the shelf break system of the Mid-Atlantic Bight using corrected sightings per trackline region, classification trees, multidimensional scaling, and random forest analysis. I describe habitat for common dolphins, Risso’s dolphins and sperm whales. From the distribution of cetacean sightings, patterns of habitat start to emerge: within the shelf break region of the Mid-Atlantic Bight, common dolphins were sighted more prevalently over the shelf while sperm whales were more frequently found in the deep waters offshore and Risso’s dolphins were most prevalent at the shelf break. Multidimensional scaling presents clear environmental separation among common dolphins and Risso’s dolphins and sperm whales. The sperm whale random forest habitat model had the lowest misclassification error (0.30) and the Risso’s dolphin random forest habitat model had the greatest misclassification error (0.37). Shallow water depth (less than 148 meters) was the primary variable selected in the classification model for common dolphin habitat. Distance to surface density fronts and surface temperature fronts were the primary variables selected in the classification models to describe Risso’s dolphin habitat and sperm whale habitat respectively. When mapped back into geographic space, these three cetacean species occupy different fine-scale habitats within the dynamic Mid-Atlantic Bight shelf break system. </p><p>In Chapter Five I present a summary of the previous chapters and present potential analytical steps to address ecological questions pertaining the dynamic shelf break region. Taken together, the results of my dissertation demonstrate the use of opportunistically collected data in ecosystem studies; emphasize the need to incorporate middle trophic level data and oceanographic features into cetacean habitat models; and emphasize the importance of developing more mechanistic understanding of dynamic ecosystems.</p> / Dissertation

The study documents seagrass patch dynamics over large spatial extents in Tampa Bay, Florida. Using GIS techniques a set of fine scale seagrass maps was created within locations previously identified as "patchy" seagrass or areas of seagrass loss. Thirty randomly selected landscape windows of various extents were mapped for the years 2004, 2006, and 2008 by visualizing 0.3 m resolution color imagery on-screen at a digitizing scale of 1:500 using a minimum mapping unit of 1 m2. Characteristics of seagrass patches and patterns of seagrass change were quantified using area-based and time interval metrics including total seagrass area, percent change in seagrass area, seagrass percent cover, and number of patches. Patterns of change were then reviewed at multiple levels of spatial organization and multiple temporal scales. Results from seagrass mapping generated from the fine scale (1 m2 resolution) and previously-reported broad scale (2.02 ha resolution) mapping approaches were also compared. The study documented seagrass patches ranging in size from 1 m2 to greater than 10,000 m2. The fine scale mapping data reported a net increase in seagrass cover from 2004 to 2008. However, only 19 landscape windows were either stable in cover or contributed to the gains in seagrass documented during the study. The remaining 11 landscape windows exhibited various temporal patterns in seagrass loss where patch contraction, complete patch mortality, seagrass fragmentation, and seagrass gap formation were all documented. Results from fine scale mapping indicate that the amount of total seagrass patch area represented by locations categorized as "patchy" in broad scale mapping were, on average, 44 percent less than estimated by the broad scale maps. Together these findings provide new information on how different mapping techniques may produce variable views of seagrass dynamics.

Elucidating the ecological determinants of community structure and how they vary spatially has a long history in ecology, but there still is no consensus on the mechanisms behind diversity patterns. The primary objective of this dissertation was to focus on spider assemblages to investigate how the fine-scale habitat associations of organisms may drive their community composition at larger scales. Research was conducted in the Bear River Mountains, Utah, in an attempt to elucidate the potential role of species-microhabitat associations in driving three well-known patterns of community composition that have typically been investigated at broad scales: 1) elevation gradients of species diversity, 2) the response of species assemblages to neighboring habitat structure and 3) community composition at the edges of habitat patches. Slope aspect was a significant predictor of spider density and species richness when communities were compared at the same elevation, suggesting that fine-scale topographic variables may play an important role in shaping elevational patterns of species composition. Cursorial spider composition was strongly linked to site temperature only, whereas differences across web spider assemblages significantly increased with dissimilarities in woody plant cover and temperature. The study on the effects of neighboring habitat structure revealed markedly reduced cursorial spider densities in shrubs without surrounding structure, and more cursorial species in control shrubs, whereas web spiders lacked any significant response to treatments. These contrasting responses indicate that data should be collected at larger spatial extents for mobile species, and that mobility may mediate the outcome of surrounding habitat modifications on the local composition of communities. In the last study, I focused on communities in which the edge-dwelling spiders Theridion and Dictyna strongly differed in terms of concealment and substrate generalization and found that microhabitat choice may affect the sensitivity of species to habitat geometry, a characteristic associated with habitat fragmentation. This work suggests that a better understanding of the links between the biological traits of species and their fine-scale environmental requirements may help uncover the mechanisms behind spatial patterns of community composition at larger scales.

<p> An analysis was performed using LANDSAT Thematic Mapper digital imagery to determine the feasibility of fine scale vegetation classification in southern Ontario. </p> <p> MICROPIPS, an image processing program, was used to analyse the Thematic Mapper data, based on spectral response patterns of different land cover types. Final classified images were compared with vegetation classifications as determined by the Royal Botanical Gardens, in Hamilton, Ontario. </p> <p> It was concluded, that it was possible to classify land cover types using MICROPIPS, but only at a general level. Thus, it was not feasible to classify vegetation on a fine scale. </p> / Thesis / Candidate in Philosophy

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