Biological Sciences - Theses, Dissertations, and other Required Graduate Degree Essays

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The biological effects of diluted bitumen (dilbit) on two species of Pacific salmonid: Sockeye (Oncorhynchus nerka) and pink salmon (Oncorhynchus gorbuscha)

Author: 
File(s): 
Date created: 
2020-10-16
Supervisor(s): 
Christopher J. Kennedy
Department: 
Science: Biological Sciences Department
Thesis type: 
(Thesis) Ph.D.
Abstract: 

The major petroleum product derived from the Canadian Alberta oil sands is bitumen, which is commonly mixed with diluents to produce several blends of diluted bitumen (dilbit). The prospected expansions of dilbit transportation capacity in coastal regions of British Columbia (BC) increase the risks of accidental releases of dilbit into freshwater and marine environments of particular concern are the potential risks of exposure to sensitive Pacific salmonids. The central goal of this research was to generate new empirical data to characterize the toxicity of the water-soluble fraction (WSF) of unweathered Cold Lake Blend dilbit to two Pacific salmon species: sockeye (Oncorhynchus nerka) and pink salmon (Oncorhynchus gorbuscha). A comprehensive suite of studies examined the acute and chronic toxic outcomes including lethality, effects on growth, swimming performance, exercise recovery capacity, body energetics, the interrenal stress response, iono-osmoregulatory ability, immune function, and genetic responses. Exposure of sockeye from the fertilized embryos to swim up stage resulted in increased mortality, impaired growth, as well as reductions in both critical (Ucrit) and burst swimming speed (Uburst) in free-swimming fry. These effects correlated with alterations in energy substrate reserves at all stage and an interference in the utilization of lipid energy sources and the ability to mount a physiological stress response. Exposure of juvenile salmonids to the WSF of dilbit (at TPAC concentrations at the ppb level) resulted in sublethal effects that included a classic physiological stress response, and alterations in iono-osmoregulatory homeostasis and immunological performance. Reductions in swimming performance were correlated with a significantly diminished aerobic scope following exposure and recovery following burst exercise was altered. In experiments with juvenile pinks, A 3 month exposure at varying salinity and temperature showed that higher temperatures and salinities affected dilbit-induced mortality, growth, osmoregulation, and energy storage. In a larger context, the findings here provide necessary toxicological information required for the development of risk assessment plans for managing salmon populations and restoring habitat in the event of potential pipeline failures or tanker spill.

Document type: 
Thesis

Satellite telemetry reveals habitat selection decisions by black oystercatchers across seasonal, diel, and tidal cycles

Author: 
File(s): 
Date created: 
2021-12-03
Supervisor(s): 
David Green
Department: 
Science: Biological Sciences Department
Thesis type: 
(Thesis) M.Sc.
Abstract: 

Habitat use of indicator species is used to prioritize management activities, but habitat use can vary temporally in response to changes in predation risk and foraging rewards. I examined black oystercatcher habitat preferences at four sites in BC, Canada, during the breeding and non-breeding season, and across diel and tidal cycles. Oystercatchers generally preferred islets and shoreline with limited tree cover that provide a refuge from predators and shoreline associated with freshwater outflows and larger intertidal areas that provide greater foraging rewards. However, preferences varied temporally in response to differences in predation risk and foraging rewards. Across the year, Individuals made greater use of larger islets with few surrounding trees and freshwater outflows with gravel substrates. My study highlights the importance of examining habitat use throughout the annual cycle and suggests that managers should protect a mosaic of marine shoreline providing both refuge from predators and productive foraging opportunities.

Document type: 
Thesis

Paying attention but not coordinating: Parental care in European starlings (Sturnus vulgaris)

Author: 
File(s): 
Date created: 
2021-09-15
Supervisor(s): 
Tony Williams
Department: 
Science: Biological Sciences Department
Thesis type: 
(Thesis) M.Sc.
Abstract: 

Sexual conflict occurs in biparental species because working together provides shared benefits while incurring individual costs. In birds, coordination of provisioning visits via turn-taking has been proposed as a strategy to mitigate this conflict. However, alternation of visits requires that birds have access to reliable information on their partner’s behaviour. I investigated coordination in the European starling, Sturnus vulgaris, where direct access to information is variable and limited. Using observational data and a short-term mate removal experiment, there was evidence that individuals adjusted their behaviour in response to their partner. Both sexes decreased their provisioning in the hour the partner was removed but returned to pre-experimental levels within 24 hours, which is consistent with “matching” of parental effort, rather than a “compensation” response widely reported in other studies. Despite this, there was no evidence of coordination, both alternation and synchrony of visits did not differ from that expected by chance.

Document type: 
Thesis

Disentangling the effects of biogeoclimatic factors and local stressors on breeding harlequin duck presence and abundance using field surveys, MaxEnt, and stable isotope turnover models

Author: 
File(s): 
Date created: 
2020-12-10
Supervisor(s): 
Ronald Ydenberg
Susan Bertram
Department: 
Science: Biological Sciences Department
Thesis type: 
(Thesis) Ph.D.
Abstract: 

Harlequin ducks breed at low densities on montane streams across a large geographic region. Variation within and between watersheds can make it difficult to isolate the effects of local stressors within a broader suite of overlapping and interacting environmental factors influencing harlequin presence and abundance. For example, fish introductions may lower harlequin breeding habitat quality, either directly, through competition for food resources, or indirectly, by inducing antipredator behaviours in shared invertebrate prey or attracting predators, such as eagles. However, fish presence can be confounded with stream size, elevation, and reach gradient. To disentangle these effects, I used field surveys and complementary habitat suitability modeling in MaxEnt. I constructed candidate models using suites of biogeographic variables hypothesized to affect breeding harlequin duck presence and abundance. Proportion of grassland and shrubland was the best predictor of true absences in the field surveys, denoting unsuitable harlequin habitat. Annual temperature range contributed the most information to the final MaxEnt model, with low temperature range being most suitable (coast and mountains). Both analyses found habitat suitability increased with stream order, but order alone was insufficient in predicting harlequin distributions, likely because stream orders were fairly evenly distributed. Overall, climate and distance to coast appeared to constrain harlequin distributions at the broadest spatial scale while stream order seemed to be a subsequent environmental “filter.” Lastly, I tested the feasibility of making inferences about breeding habitat using body tissue stable isotopes from recent arrivals to the wintering grounds. To account for the incorporation of wintering habitat isotopes, I created models of claw and blood cell isotopic turnover using flight feather regrowth as an index of time since arrival. Claw turnover mirrored blood cell turnover, but with a “lag” due to the time required for “current” claw tissue isotopes to grow from the base to the tip of the claw. In stream invertebrates collected during the field surveys, δ13C decreased with distance from the coast while δ15N increased with river order. As both factors were also associated with habitat suitability, isotope turnover back-calculations may offer a large scale method to examine harlequin duck breeding habitat usage.

Document type: 
Thesis

Range-wide life-history diversity and climate exposure in Chinook salmon

Author: 
File(s): 
Date created: 
2022-01-25
Supervisor(s): 
Jonathan Moore
Department: 
Science: Biological Sciences Department
Thesis type: 
(Thesis) M.Sc.
Abstract: 

Climate change risk for migratory species is intertwined with their life-history diversity. Here I quantify climate risk, exposure, and phenological adaptive capacity in Chinook salmon during their spawning migrations for populations from across their North American range. First, I assessed how migration timing varies with watershed characteristics. Populations with longer migration distances and from higher elevations entered freshwater earlier. Second, I quantified climate exposure and risk by linking migration timing data to recent (1990s) and future (2040s) water temperatures. Nearly a quarter of populations will be exposed to future temperatures above thermally stressful thresholds. Third, I assessed the rate and direction of phenological shifts that would enable Chinook to adapt to climate warming. Spring populations would need to shift earlier, while fall populations would need to shift later. Broadly, my thesis highlights that climate exposure, risk and adaptive capacity are structured by phenology and latitude in a diverse migratory species.

Document type: 
Thesis

Enhancing the growth and health of sockeye salmon (Oncorhynchus nerka) in land-based freshwater aquaculture

Author: 
File(s): 
Date created: 
2021-12-08
Supervisor(s): 
Vicki Marlatt
Department: 
Science: Biological Sciences Department
Thesis type: 
(Thesis) M.Sc.
Abstract: 

The goal of this research was to provide data to assist in optimizing freshwater aquaculture practices for sockeye salmon (Oncorhynchus nerka), and specifically, for LSL a land-based, freshwater sockeye salmon farm. Thus, this study successfully conducted inaugural trials using 17 beta-estradiol waterborne treatments (200 μg/L, 400 μg/L and 800 μg/L) to feminize genetic males to develop an enhanced male population to achieve larger sized sockeye at slaughter. In addition, this study tested the effects of weekly netting stress over 100 days and revealed a significant reduction in body weight and length of juveniles, and a change in the abundance of three liver proteins involved in the immune-responsive gene regulation, protein processing and cytoskeletal structure organization. However, bacterial kidney disease prevalence, leukocyte count, hematocrit, and whole-body cortisol level were not affected. This research shows that mild physical stress does compromise growth in juvenile sockeye salmon and would restrict commercial production substantially.

Document type: 
Thesis

Functional roles of sea cucumbers in a coral reef-seagrass ecosystem

Author: 
File(s): 
Date created: 
2021-08-16
Supervisor(s): 
Isabelle Côté
Department: 
Science: Biological Sciences Department
Thesis type: 
(Thesis) M.Sc.
Abstract: 

Animals can mediate energy and material movement within a system, which can drive ecosystem function. Through excretion and egestion, animals can supply ammonium to nutrient-poor tropical marine systems, potentially altering primary productivity. My thesis explores how sea cucumber identity influences rates of ammonium excretion and bioturbation, and how this affects seagrass growth in The Bahamas. I quantified ammonium excretion and bioturbation rates in two species, Holothuria mexicana and Actinopyga agassizii, and found that H. mexicana excretes ammonium and bioturbates sediment at higher rates per-individual. I conducted a manipulative field experiment to test whether the differences I found between species translate to differences in seagrass productivity when one sea cucumber species is replaced by the other. I found that fish biomass was more important in predicting seagrass responses than sea cucumber identity or density, and that reef proximity and sampling day best predicted all seagrass responses. My research suggests that species-specific differences in bioturbation and ammonium excretion rates by sea cucumbers do not extrapolate at the ecosystem level. Thus, H. mexicana and A. agassizii may be functionally redundant, at least in terms of nutrient provisioning, in the patch reef-seagrass system I investigated in The Bahamas.

Document type: 
Thesis

Assessment of biotransformation rates of organic compounds in mammals using in-vitro S9 bioassays

Author: 
File(s): 
Date created: 
2021-11-08
Supervisor(s): 
Frank Gobas
Department: 
Science: Biological Sciences Department
Thesis type: 
(Project) M.E.T.
Abstract: 

The overall objective of this study was to develop an in vitro based screening approach to determine the biotransformation rate constants of neutral hydrophobic organic chemicals in rats from rat liver S9 bioassays, and to test this screening approach by comparing in-vitro predicted biotransformation rates to in-vivo measured biotransformation rates. The test chemicals used for this study were pyrene, benzo(a)pyrene, hexachlorocyclohexane-beta, methoxychlor, mono-n-butyl phthalate, and 4-n-nonylphenol. In-vitro biotransformation rate constants were successfully obtained for all test chemicals and extrapolated to whole organism biotransformation rate constants using various IVIVE models. All the model outputs (IVIVE & QSAR) were compared to one another using descriptive statistical analysis. Various statistical parameters imply that all IVIVE models are very similar in performance. This indicates that the IVIVE-b model and IVIVE-Krause & Goss model (blood flow not considered), which require fewer biological parameters, could be used instead of the IVIVE-ph and IVIVE-Krause & Goss model (blood flow considered) for bioaccumulation assessment. Additionally, the IVIVE models were shown to perform slightly better than the QSAR models, indicating that the IVIVE models might be a better tool for estimating biotransformation rate constants compare the QSAR models. However, due to the variability in the in-vivo data and only a few chemicals being tested, a definitive conclusion cannot be made regarding which model performs the best. Furthermore, the IVIVE and QSAR models could be further upgraded in the future and only time will tell which models are the best for predicting whole organism biotransformation rate constants in rats.

Document type: 
Graduating extended essay / Research project

Managing emerging diseases of organic greenhouse vegetables: Interactions between vermicompost and biological control agents

Author: 
File(s): 
Date created: 
2021-05-07
Supervisor(s): 
Zamir Punja
Department: 
Science: Biological Sciences Department
Thesis type: 
(Thesis) Ph.D.
Abstract: 

Biological control agents and composted materials, including vermicomposts and their water extracts, are used to suppress plant diseases in organic production systems, where fungicide use is limited. The past decade has seen a doubling in organic horticulture and a dramatic increase in vermicompost research. As disease suppression by vermicomposts has been inconsistent, research in this area requires standardization of methods, and compatibility with current biocontrol agents has not been assessed. I tested the disease suppressive abilities and microbial communities of five vermicomposts with differing characteristics, and developed Petri dish and growth chamber assays to examine compatibility with biocontrol agents. In vitro suppression of the pathogens Fusarium oxysporum f. sp. radicis-cucumerinum D.J. Vakalounakis (Forc), and Rhizoctonia solani J.G. Kühn, as well as disease suppression on cucumber and radish plants, respectively, was assessed using vermicomposts incorporated into sterilized substrate and using aerated vermicompost water extract. All vermicomposts provided significant pathogen suppression in vitro as well as plant disease suppression. The mechanism for pathogen suppression was negated by autoclaving. A range of responses between the biocontrol agents Bacillus subtilis (Ehrenberg) Cohn strain QST 713 (Rhapsody®) and Clonostachys rosea f. catenulata Samuels, Seifert, and Gams (syn, Gliocladium catenulatum) strain J1446 (Prestop®), and vermicomposts, was observed in vitro. I tested for interactions between these biocontrol agents and vermicomposts as an example of application of a biological control agent to a microbially competitive growth medium using a mixed effects model approach. Consistent antagonistic to neutral interactions in vitro, and a range of interactions from antagonistic to additive in planta, suggest that the interaction between a biocontrol agent and a competitive microbial milieu is not additive. The testing strategies investigated provide an efficient screen of vermicomposts for compatibility with existing biocontrol agents, and of biocontrol agent efficacy in a competitive environment. With improved and consistent testing methods, vermicompost can be a reliable approach for plant disease management in organic agriculture.

Document type: 
Thesis

Foraging ecology of the Northern Goshawk in coastal British Columbia

Author: 
File(s): 
Date created: 
2021-07-21
Supervisor(s): 
David Green
Department: 
Science: Biological Sciences Department
Thesis type: 
(Thesis) M.Sc.
Abstract: 

Effective wildlife conservation requires understanding diet composition and its consequences for population demography. I measured the diet of an at-risk population of Northern Goshawks (Accipiter gentilis) in southwestern British Columbia during two breeding seasons using pellets, prey remains, and nest cameras. I compared diet composition across two ecological zones and assessed the impact of dietary diversity and specialization on goshawk productivity. Goshawks consumed 33 different species but primarily consumed pine squirrels (Tamiascuirus spp.), which composed 14-61% of dietary biomass, depending on source. Diet composition differed slightly between the coastal and transition zones. I also conducted a pilot study of goshawk breeding season movement using GPS-UHF transmitters. Male goshawks used more space and travelled further from the nest than female goshawks. While I found no correlation between dietary diversity or specialization on pine squirrels and goshawk productivity, the abundance of this key prey species may affect goshawk productivity and space use.

Document type: 
Thesis