Graduate Theses & Dissertations


Habitat Characteristics, Density Patterns and Environmental Niches of Indo-Pacific Humpback Dolphins (Sousa chinensis) of the Pearl River Estuary and Eastern Taiwan Strait
The purpose of this thesis is to quantify the habitat characteristics, density patterns and environmental niches of two groups of Indo-Pacific humpback dolphins: Chinese white dolphins (CWD) of the Pearl River estuary (PRE), and Taiwanese white dolphins (TWD, =Taiwanese humpback dolphin, THD) found in the eastern Taiwan Strait (ETS). Much work has already been done on the habitat use of CWDs in parts of the PRE, so the purpose of my first two chapters was to advance knowledge of the TWD to a comparable level. Chapter 2 contains the first published description of the relatively shallow, inshore, estuarine habitat of the TWD. General environmental characteristics and observed group sizes were consistent with other populations of humpback dolphins, and group sizes were not correlated with the environmental variables measured during surveys. Chapter 3 investigated density patterns of TWDs, finding spatiotemporal heterogeneity across the study area. Humpback dolphin densities fluctuated from year to year, but some parts of the study area were consistently used more than others. Environmental characteristics again did not influence dolphin densities, though more dolphins than expected were sighted in waters adjacent to major land reclamations, which may be related to the location of these areas close to major rivers. In Chapter 4, niches of the TWD and CWDs found in the PRE were compared using species distribution models, which indicated significant niche overlap. This may be due to niche conservatism maintaining similar fundamental niches between the two groups since their historical split >10,000 years ago, or a result of the intrinsic biotic factors that influence occurrence data affecting the hypervolume dimensions of each realized niche in similar ways. Geographic predictions indicate that most of the TWD’s range has likely been surveyed, and that there may be connectivity between PRE humpback dolphins and at least one neighbouring putative population due to continuous predicted suitable habitat in waters that remain poorly surveyed. Overall, my thesis demonstrates that density patterns may vary over time, but on a broad temporal scale, these two allopatric groups of Indo-Pacific humpback dolphins have similar habitat requirements in geographically isolated, but environmentally similar locations. Author Keywords: density, habitat, Indo-Pacific humpback dolphin, niche overlap, Sousa chinensis, species distribution model
Temporo-spatial patterns of occupation and density by an invasive fish in streams
Since its introduction to North America in the 1990s, the Round Goby has spread throughout the Great Lakes, inland through rivers and is now moving into small tributary streams, a new environment for this species in both its native and invaded ranges. I explored density and temporal occupation of Round Gobies in four small streams in two systems in south-central Ontario, Canada in order to determine what habitat variables are the best predictors of goby density. Two streams are tributaries of Lake Ontario and two are tributaries of the Otonabee River, and all of these streams have barriers preventing upstream migration. I found that occupation and density differed between the systems. In the Otonabee River system, Round Gobies occupy the streams year round and the most important factor determining adult density is distance from a barrier to upstream movement, with the entire stream occupied but density highest next to the barriers. In the Lake Ontario system, density is highest at mid-stream and Round Gobies appear to occupy these streams mainly from spring to fall. Adult density in Lake Ontario tributaries is highest in sites with a high percentage of cobble/boulder and low percentage of gravel substrate, while substrate is less important in Otonabee River tributaries. Occupation and density patterns may differ due to contrasting environmental conditions in the source environments and distance to the first barrier preventing upstream movement. This study shows diversity in invasion strategies, and provides insight into the occurrence and movement patterns of this species in small, tributary streams. Author Keywords: biological invasion, Generalised Additive Mixed Model, habitat, Neogobius melanostomus, Round Goby, stream
Understanding Angler Dynamics in a Recreational Lake Trout (Salvelinus namaycush) Fishery in Algonquin Provincial Park Using Long-Term Access Creel Data
In order to effectively manage recreational fisheries, it is important to understand how the resource is being used. In this thesis, long-term creel census data, collected on Lake Opeongo in Algonquin Provincial Park, Ontario, Canada was used to assess fine-scale angler dynamics within a recreational Lake Trout (Salvelinus namaycush) fishery. The spatial distribution of angler reported catch locations of Lake Trout within the lake, was assessed using an Optimized Hotspot Analysis in ArcGIS. Areas of significant clustering of catch locations were revealed during all time periods and varied in size and location both seasonally and temporally. Cormack-Jolly-Seber models were used to evaluate the probability of individual angling boats persisting in the regional fishery and being detected on Lake Opeongo through time, as well as to examine the effect of angler travel distance and gas prices on participation parameters. Time-varying models revealed that the probability of an angler persisting in the fishery varied, while detection estimates remained stable. Travel distance had a negative effect on both parameters while increased gas prices only had a slight negative effect on detection estimates. Additionally, among Lake Opeongo anglers, angling avidity varied as did lake specific fishing experience. Average CUE was found to be higher among angling parties who visited the lake more often than fishing parties who visited relatively few times. Author Keywords:
Habitat use and community structure of grassland birds in southern Ontario agro-ecosystems.
Most grassland bird populations are in decline, so it is becoming increasingly important to understand how they use agricultural field types and form their communities. I performed point counts in cultural meadow, intensive agriculture, and non-intensive agriculture areas in 2011 and 2012. Generalized linear models were used to determine the habitat relationships of six focal species. I found that non-intensive agriculture was used most often and intensive agriculture was often avoided, but there were exceptions which indicate habitat use can be species-specific. I determined in which habitats competition was likely occurring and which species pairs were competing in 2011. In 2012, I experimentally tested these relationships by introducing artificial competitors onto sites. By comparing presence-absence data from 2011 to 2012, I found evidence of habitat-mediated interspecific and conspecific attraction involving Bobolink and Grasshopper Sparrow. This research contributes to the current understanding of grassland bird community ecology and conservation. Author Keywords: agriculture, BACI, community ecology, habitat use, species at risk, species interactions
Changes to the Arctic and sub-Arctic climate are becoming increasingly evident as it warms faster than other areas of the globe, supporting evidence that predictions of future warming will be amplified due to positive feedback mechanisms. The Southern Hudson Bay polar bear (Ursus maritimus) subpopulation is one of the most southerly subpopulations in the world, putting it at increased risk due to effects of climate change. Whereas many other subpopulations have been the subject of intense research and monitoring, little research has been completed detailing the movement behaviour and space use of bears within Southern Hudson Bay. I used detailed movement data collected on female polar bears to establish a baseline of movement information for this subpopulation to which future work can be compared and effects of climate change can be assessed I evaluated the use of core areas during critical periods of the year (breeding and ice breakup) and evaluated common space use as a means of assessing site fidelity during the breeding season. Movement rates and home range sizes were comparable to those of the neighbouring Western Hudson Bay subpopulation. I also found evidence of increased occurrences of long distance, late fall movements along the coast to the northwest, presumably to gain earlier access to first ice. Though space use analysis did not reveal evidence of site fidelity to specific breeding areas in Hudson Bay, I found that core use areas are at risk of substantially shortened ice duration (x¯ =76 days shorter) using projected ice data based on the high emissions A2 climate change scenario. Author Keywords: climate change, Hudson Bay, movement, polar bear, sea ice, utilization distribution
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
spatial and temporal distribution of tabanid (Chrysops, Hybomitra and Tabanus) species in the Nakina district of northwestern Ontario
This thesis focused on expanding knowledge of Hybomitra, Chrysops and Tabanus (Diptera: Tabanidae) distributions north of Lake Nipigon, Ontario, in a managed boreal forest. As land use and climate changes accelerate, there is increased pressure to increase knowledge from which to monitor changes. In 2011 and 2012, 8928 individuals representing, 44 species were captured using sweep netting. Major northward range extensions were observed for Chrysops shermani, C. aberrans and Tabanus fairchildi. Smaller range extensions and in-fills were observed for another 15 species. 23 species had exntensions to their previously known seasonal range. C. carbonarius was the only species that showed an extension to both sides of its season. In general, harvested stands had 50% more individuals and 30% greater species richness than younger stands. A possible link between stand age and interspecific competition was identified. Information has been provided to build baseline of species richness, relative abundance and distribution of Tabanid flies. Author Keywords: diptera, distribution, natural history, northern Ontario, species range, tabanid
Eco-evolutionary Dynamics in a Commercially Exploited Freshwater Fishery
Fisheries assessment and management approaches have historically focused on individual species over relatively short timeframes. These approaches are being improved upon by considering the potential effects of both broader ecological and evolutionary processes. However, only recently has the question been raised of how ecological and evolutionary processes might interact to further influence fisheries yield and sustainability. My dissertation addresses this gap in our knowledge by investigating the role of eco-evolutionary dynamics in a commercially important lake whitefish fishery in the Laurentian Great Lakes, a system that has undergone substantial ecosystem change. First, I link the timing of large-scale ecological change associated with a species invasion with shifts in key density-dependent relationships that likely reflect declines in the population carrying capacity using a model selection approach. Then, using an individual-based model developed for lake whitefish in the southern main basin of Lake Huron, I demonstrate how ecosystem changes that lower growth and recruitment potential are predicted to reduce population productivity and sustainable harvest rates through demographic and plastic mechanisms. By further incorporating an evolutionary component within an eco-genetic model, I show that ecological conditions also affect evolutionary responses in maturation to harvest by altering selective pressures. Finally, using the same eco-genetic model, I provide a much-needed validation of the robustness of the probabilistic maturation reaction norm (PMRN) approach, an approach that is widely used to assess maturation and infer its evolution, to ecological and evolutionary processes experienced by exploited stocks in the wild. These findings together highlight the important role that ecological conditions play, not only in determining fishery yield and sustainability, but also in shaping evolutionary responses to harvest. Future studies evaluating the relative effects of ecological and evolutionary change and how these processes interact in harvested populations, especially with respect to freshwater versus marine ecosystems, could be especially valuable. Author Keywords: Coregonus clupeaformis, density-dependent growth, fisheries-induced evolution, individual-based eco-genetic model, Lake Huron, stock-recruitment
Biogeography of Carabidae (Coleoptera) in the Boreal forest
Basic biogeographic information is lacking for many species, such as where species are found, and how they dispersed there. Using ground beetles collected during 2008-2015 from across northern Ontario and Akimiski Island, Nunavut, I present new information on ground beetle distribution in this eastern Nearctic boreal forest, including 2 first Canadian records, 9 first provincial and 48 first territorial records, as well as 74 new records that extend the known range of many large and common ground beetles several hundred kilometres. I used these distributions to redress the knowledge gap that includes fundamental distribution data, i.e. the Wallacean shortfall, and to inform later chapters in my thesis.In Chapter 3, I examine the range expansion pattern of Carabus granulatus, a non-native species, as it spread across northeastern North America and I provide a new range record. Northern Ontario is already under threat from non-native species entering the region and it is important to conduct studies in the region before more disturbance associated with development occurs. In Chapter 4, I examine the hypothesis that northern Ontario effectively acts as a climate plateau for poikilotherms, using the predictions from Bergmann's rule as my metric. The body length of ground beetles does not appear to change over the small temperature gradient that exists across northern Ontario latitudes, supporting the climate plateau hypothesis. In Chapter 5, I test hypotheses about dispersal mechanisms that contributed to post glacial re-establishment of ground beetles using predictions of geographic distribution patterns as metrics. I found that ground beetles were likely carried downstream by rivers which aided their dispersal northward from southern refugia. I infer from the current geographic distributions that flightless ground beetle species are still expanding their range in this boreal region. Finally, I argue that there is an urgent need for more basic research on species distributions while it is still possible in regions like northern Ontario, before increased industrial and agricultural development, and expanding resource extraction projects obliterate evidence of historic ecological processes. Author Keywords: Boreal forest, Carabidae, Coleoptera, Passive dispersal, Post-glacial distribution, Range extension
Indirect Effects of Hyperabundant Geese on Sympatric-Nesting Shorebirds
Rising populations of Lesser Snow and Ross’ geese (hereafter collectively referred to as light geese) breeding in the North American Arctic have caused significant environmental change that may be affecting some populations of nesting shorebirds, which in contrast to geese, have declined dramatically. In this thesis I examine the indirect effects of light geese on sympatric-nesting shorebirds. I first conduct a literature review of the effects of light geese on northern wildlife and outline multiple mechanisms in which geese may affect shorebirds in particular. Using bird survey data collected in plots situated across the Canadian Arctic from 1999 to 2016, I then identify spatial effects of light goose colonies on shorebird, passerine, and generalist predator densities. The densities of cover- nesting shorebirds and passerines were depressed near goose colonies while the densities of open-nesting shorebirds were less so. Next, using habitat data collected at random sites and shorebird nest sites situated at increasing distances from a goose colony on Southampton Island, Nunavut, I outline the effects of geese on shorebird nest site selection. I found that the availability of sedge meadow and amount of lateral concealment increased as a function of distance from goose colony; cover-nesting shorebirds selecting nest sites with less concealment and sedge meadow near the colony. Then, to characterize spatial effects of light geese on predators and risk of predation I used time-lapse cameras and artificial shorebird nests placed at increasing distances from the goose colony. Activity indices of gulls, jaegers, and foxes were all negatively correlated with distance from the goose colony while the reverse was true for artificial nest survival probability. Finally, I relate changes in ground cover to goose use and link these changes to variation in invertebrate communities. I then use DNA metabarcoding to characterize the diet of six shorebird species across study sites and identify inter-site variation in the biomass of dominant shorebird prey items. Prey item biomass was elevated at the two study sites near the goose colony potentially indicating an enhancing effect of goose fecal deposition. Overall, I show that light geese interact with shorebirds in multiple ways and negatively affect their habitat availability, nest site selection, and risk of predation, effects that likely outweigh the positive effects of enhanced prey availability. Author Keywords:
Patterns of Vegetation Succession on Nickel-Copper Mine Tailings near Sudbury, Ontario
Natural establishment of vegetation on mine tailings is generally limited. Understanding the processes leading to vegetation germination and the survival mechanisms that vegetation species employ in these harsh environments is critical to future remediation efforts. As metalliferous mine tailings are generally nutrient-poor, high in harmful metals, and acidic, vegetation species require distinct mechanisms to germinate and survive in such harsh environments. In this study, edaphic and biotic factors linked to vegetation establishment and diversity were studied at two nickel-copper (Ni-Cu) tailings sites near Sudbury, Ontario. One site had experienced minimal treatment, and the second site was split into partial (hand-distribution of lime) and full (lime, fertilizer, seeding) treatment areas. Tailings were generally acidic, low in organic matter and “available” nutrients, and high in metals such as Al, Cu, Fe, and Ni, but these physical and chemical properties were extremely spatially variable. At both sites, vegetation was distributed in sparse patches, with the greatest diversity in treated areas. There was no clear link between metals and vegetation establishment/diversity at the sites. The primary limiting nutrients on the tailings were phosphorous (P) and potassium (K), and while there were areas of increased soil fertility at the sites, they were not clearly associated with increased vegetation diversity. Both traditional ecological succession and nucleation succession patterns were observed on the site, and the chief species associated with nucleation were primary colonizing trees such as B. papyrifera and P. tremuloides. The relationship between B. papyrifera nutrient retranslocation and tailings restoration was assessed and while B. papyrifera at the sites were deficient in P and K, the trees efficiently retranslocated both P and K during senescence. This research can provide insight into possibilities for future revegetation of similar tailings, enabling industry to make educated decisions when choosing where and how to revegetate, mimicking natural succession patterns. Author Keywords: Acid-mine drainage, Betula papyrifera, ecosystem health, metals, Sudbury, tailings
multi-faceted approach to evaluating the detection probability of an elusive snake (Sistrurus catenatus)
Many rare and elusive species have low detection probabilities, thereby imposing unique challenges to monitoring and conservation. Here, we assess the detection probability of the Eastern Massasauga (Sistrurus catenatus) in contrast to a more common and conspicuous species, the Eastern Gartersnake (Thamnophis sirtalis). We found that patterns of detection probability differed between species, wherein S. catenatus was detected less often and under a more specific set of sampling conditions. Correspondingly, detection trials with S. catenatus found a high non-detection rate, while detection trials with artificial models suggest that regional differences in detection probability are driven by variation in population density and habitat use. Our results suggest that current monitoring efforts are not sufficient, and that S. catenatus is frequently undetected. Accordingly, we highlight the importance of species-specific monitoring protocols when monitoring rare and elusive species, and recommend a multi-faceted approach that estimates detection probability and identifies species-specific challenges to monitoring. Author Keywords: detection probability, elusive species, monitoring programs, non-detection, S. catenatus, snakes


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