2021 Fall Convocation

The following students will receive their degrees/certificates during the University of Saskatchewan (USask) virtual Fall Convocation on November 10, 2021.  

Click on the bars below for more information.

Veterinary Microbiology

  • Supervisor: Dr. Janet Hill, Department of Veterinary Microbiology, WCVM
  • Thesis title: “Determination of factors affecting the community structure of Gardnerella spp. in the vaginal microbiome.”
  • Click here to read thesis

Snapshot

Gardnerella spp. bacteria are a hallmark of bacterial vaginosis (BV) — an imbalance that occurs when the healthy, Lactobacillus spp.-dominated vaginal microbiota is replaced by BV-related bacteria. BV is highly prevalent in women during their reproductive years and known to be associated with pre-term delivery and increased susceptibility to sexually-transmitted diseases.

Gardnerella spp. are diverse bacteria that likely differ in their roles in causing the development of BV. Multiple subgroups of Gardnerella usually colonize simultaneously, and due to the limited nutrients available, they likely interact to secure resources, especially when dominating the microbiome.

The study’s first objective was to determine the types of interaction between Gardnerella spp. subgroups, which are divided into A, B, C and D, corresponding to 13 different “genome species.” The research found that subgroup D grew with increasing numbers of competitors.

Despite its ability to thrive under increased competition, no one understands why Gardnerella subgroup D is so rarely abundant in the real world. This led Khan to test whether the growth rate of competing species and biofilm formation may affect the success of the subgroup.

  • Supervisor: Dr. Joe Rubin, Department of Veterinary Microbiology, WCVM
  • Thesis title: “Improving diagnostic methods and processes for the identification and characterization of Brachyspira.”
  • Click here to read thesis

Snapshot

There are no standardized tests to determine the effectiveness of antimicrobial drugs against Brachyspira spp., a bacterium that can cause swine dysentery. Instead, laboratories rely heavily on in-house methods, which produce highly variable test results. Treatment choices for swine dysentery are often made empirically, which can lead to increasing levels of antimicrobial resistance.

The study had several goals: to develop a standardized method for understanding how effective antimicrobials are against a collection of Brachyspira isolates; to develop feasibility methodology for antimicrobial susceptibility testing to include in the diagnostic workflow; to develop tools to help make decisions around what the diagnostic objectives are, and to investigate the genetic basis for resistance to protein synthesis inhibitory drugs (antibacterial drugs).

As part of this research, Kulathunga created a standard antibiotic susceptibility test with good reproducibility and calculated material and technical cost for all diagnostic tests. Kulathunga also created decision trees that can guide clinicians in selecting the most cost-effective tests needed to meet their diagnostic objectives. The research team also identified the isolates that carried resistance genes to two different types of antimicrobials and developed a test to screen for the two resistance genes and predict resistance of clinical isolates.

Overall findings and these novel test methods will help improve the diagnostic workflow for the identification of Brachyspira-associated diseases and support veterinarians for rapid diagnosis and evidence-based selection of antimicrobials to improve treatment outcome.

  • Supervisor: Dr. Jeffrey Chen, Department of Veterinary Microbiology, WCVM
  • Thesis title: “Experimental infection of pigs with Mycobacterium bovis and Mycobacterium tuberculosis: towards a porcine model of human tuberculosis.”
  • Click here to read thesis

Snapshot

While the study of the origin and development of tuberculosis disease (TB) has benefited from the use of animal models such as mice, guinea pigs and rabbits, these models have limitations in how they mimic different aspects of human tuberculosis — with the exception of non-human primates (NHPs). The domestic pig, which shares many similarities to humans with respect to pulmonary anatomy, physiology and immunology, is an equally suitable but more economical alternative to the NHP model. 

To determine the efficacy of pigs as a model for human tuberculosis, Niroula infected groups of mix-breed pigs with M. tuberculosis and M. bovis and monitored them. The pigs were infected both intravenously and through aerosolized forms of the diseases to naturally mimic the route of infection.

Pigs infected intravenously with M. bovis experienced more severe sickness and earlier death, accompanied by higher tissue bacterial burden and tissue death necrosis compared to pigs challenged intravenously with M. tuberculosis. Pigs given high doses of aerosolized M. bovis showed lower weight gain than pigs given high doses of aerosolized M. tuberculosis. The M. bovis group also showed more severe disease and lesions in the lungs than the M. tuberculosis group. Those given a high dose of M. bovis showed higher bacterial burden and reactivation of infection. Niroula noted that the peripheral immune responses — evaluated by the level of interferon gamma (IFN-y) cytokine, or immune system cells, that regulate immune response — were similar for both M. bovis- and M. tuberculosis-challenged pigs for all doses. 

Based on their results, the research team concluded that M. bovis is more virulent in domestic pigs than M. tuberculosis. Domestic pigs also seem better at tolerating M. tuberculosis infection. M. bovis or M. tuberculosis can be used to model tuberculosis in domestic pigs, depending on whether a researcher is attempting to model an active or latent TB infection.

Veterinary Biomedical Sciences

  • Supervisor: Dr. Michael Wu, Department of Veterinary Biomedical Sciences, WCVM
  • Thesis title: “Genetic regulators of stress-induced RNA mis-splicing in Caenorhabditis elegans.”
  • Click here to read thesis

Snapshot

Splicing of pre-mRNA, the “messenger” that tells cells how to behave, is essential for all eukaryotic dividing cells. Animals, plants, fungi and protists are all considered eukaryotic organisms, as their cells divide to replicate. Problems with the way this pre-mRNA divides during replication are involved in many human diseases including Alzheimer’s disease and cancer. However, its role isn’t clearly understood.

Scientists can study gene splicing using a tiny worm called Caenorhabditis elegans that’s about one millimetre in length. One recent discovery by the Wu lab is that exposure to the heavy metal cadmium can cause disruption of RNA splicing.

Chomyshen’s research showed that by manipulating the expression of certain protein translation related genes during splicing (by “knocking-down” or suppressing them), they could improve RNA splicing under stress – increasing the lifespan of the worms and enhancing resistance to cadmium survival.

The study’s results may imply a new mechanism through which physiological benefits can be realized by improving the quality of RNA splicing.
  • Supervisor: Dr. Dylan Olver, Department of Veterinary Biomedical Sciences, WCVM
  • Thesis title: “Exercise training improves cerebrovascular oxidative stress regulation and insulin stimulated vasodilation in juvenile and mature pigs.”
  • Click here to read thesis

Snapshot

This study examined the effect of insulin on blood vessels in the brains of pigs that took part in high-intensity interval training for eight weeks. Selective insulin resistance — shown by increased constriction of blood vessels in response to insulin — may relate to enhanced sensitivity to endothelin 1, a 21-amino acid peptide secreted by vascular endothelial cells (thin membrane lining the inside of the heart and blood vessels), or increased oxidative stress, which would lead to reduced signalling of nitric oxide (NO). This cellular messenger mediates signalling pathways and is known to play an important role in many physiological processes.

The researchers first found that the blood vessels of pigs in training responded by dilating (grew larger) in response to insulin, whereas the muscles around the blood vessels of non-exercising pigs vasoconstricted (tightened)in response to insulin.

To test the connection to oxidative stress and the role of endothelin, the researchers pre-treated the blood vessels of both groups of pigs with SOD mimetic or NOX inhibitor – compounds that change the body’s response to oxidative stress. The researchers found no difference between the two groups.  

Karsh concluded that insulin-stimulated vasoconstriction was reversable by using SOD mimetic or NOX inhibitor compounds, which connects impaired oxidative stress regulation with selective insulin resistance. Exercise training coincided with improved oxidative stress regulation simultaneously with greater insulin-stimulated cerebral vasodilation. Because the reaction of the blood vessels to endothelin 1 was similar between both groups, increased insulin-stimulated dilation of the blood vessels in exercise-trained pigs was likely the result of improved oxidative stress regulation — giving way to improvements in the NO signalling.

  • Supervisor: Dr. Dylan Olver, Department of Veterinary Biomedical Sciences, WCVM
  • Thesis title: “Cerebral blood flow during cardiopulmonary resuscitation.”
  • Thesis under embargo

Snapshot

Marshall’s research team tested if the placement of chest compressions could influence the amount of blood — and therefore, oxygen — pumped to the brain. Blood flow to the brain is vitally important for survival and recovery following a cardiac incident. Using ultrasound technology to measure brain blood flow, the team found that performing compressions over the left ventricle of the heart — as opposed to over the sternum — increased the amount of blood pumped by the heart and, most importantly, to the brain.  

This is the first research to demonstrate the effects of chest compression location on the amount of blood flow to the brain. This new knowledge could lead to more lives saved and improved recoveries for patients following a cardiac episode. Click here to read story.

Large Animal Clinical Sciences

  • Supervisor: Dr. Tasha Epp, Department of Large Animal Clinical Sciences, WCVM
  • Paper title: “The epidemiology and economics of pooled testing for disease investigations of lead exposure involving beef cattle in Saskatchewan (2007-2019).”
  • Supervisor: Dr. Yolande Seddon, Department of Large Animal Clinical Sciences, WCVM
  • Thesis title: “Practical alternatives for managing castration pain in piglets.”
  • Click here to read thesis

Snapshot

Surgical castration of piglets is a common procedure performed on males to reduce aggression, sexual behaviours and boar taint — a strong odour or taste that affects the meat of non-castrated male pigs.

The National Farm Animal Care Council’s Code of Practice for the care and handling of pigs requires producers to provide analgesics (painkilling drugs) to help control post-procedural pain. Piglets older than 10 days of age must be given an anesthetic. The code does not provide recommendations on optimal age of castration, or optimal timing to administer these drugs.

This research expands on understanding of when to castrate male piglets and how to optimally control pain. The researchers studied behaviour — navigation time in a handling chute as well as tail-wagging — and stress hormone response, as well as average daily weight gain to evaluate the differences between performing castration at three days versus 10 days of age. They also evaluated the effects of administering ketoprofen (non-steroidal anti-inflammatory pain medication) immediately versus one hour before the procedure.

The studies provide evidence that providing piglets with ketoprofen one hour before castration reduces cortisol concentrations (stress hormone response) and benefits their welfare.

  • Supervisor: Dr. Murray Jelinski, Department of Large Animal Clinical Sciences, WCVM
  • Thesis title: “An investigation of antimicrobial susceptibility and genotypes of Mycoplasma bovis isolates derived from western Canadian feedlot cattle.”
  • Click here to read thesis

Snapshot

Veterinarians and livestock producers need more information about Mycoplasma bovis (M. bovis), the bacterium that causes illness in cattle and poses a significant threat to the Canadian beef industry, particularly in feedlots. M. bovis is associated with bovine respiratory disease, chronic pneumonia and polyarthritis syndrome. Chronic M. bovis infections are resistant to antimicrobials, which result in animal welfare and economic concerns. There is no vaccine, and antibiotic drugs remain the primary option for treatment and control of M.bovis infections.

Continual surveillance of antimicrobial susceptibility is crucial for both antimicrobial stewardship and proper therapeutic treatment of M. bovis-related disease. However, the difficulty of implementing surveillance methods underscores the need for innovation — such as using whole genome sequencing, which can provide more information for investigating different aspects of the bacteria, including its susceptibility to antimicrobials and its virulence.

This study used samples from western Canadian feedlot cattle over a 12-year period, with three goals: to describe antimicrobial use and antimicrobial resistance profiles causing M. bovis deaths in feedlot cattle; to investigate antimicrobial resistance on a genetic level; and to investigate the genetic makeup of the samples, then apply and assess four different methods of genotyping.

Kinnear tested how nine commonly used antimicrobials affected the samples, and more than 90 per cent of cattle sampled had received antibiotic drugs. On average, the cattle that died of an M. bovis-related pneumonia infection received three different antibiotics.

The study increased understanding of the types of antimicrobial treatment to which the bacteria is resistant as well as the changing relationship between bacteria samples. The diversity of strain types also highlighted the structure of Canada’s cattle industry and how cattle are procured for western Canadian feedlots, illustrating how some strains of bacteria became dominant over geographical areas and over time.

  • Supervisor: Dr. Tasha Epp, Department of Large Animal Clinical Sciences, WCVM
  • Thesis title: Important canine zoonoses from a public health perspective and the introduction of companion animal surveillance in the Prairie provinces of Canada.”
  • Click here to read thesis

Snapshot

While researchers have created disease surveillance networks for people, wildlife and livestock in Western Canada, there no surveillance network for disease-causing organisms among companion animals. Gathering information on dogs — the population of animals most closely associated with people – is valuable from a One Health perspective, as the health of humans and animals is closely connected.

Sims identified this gap in public health information gathering and established a framework for monitoring of infectious disease in companion animals in the region.

Sims identified a subset of pathogens with a public health significance specific to dogs in the Prairie provinces by creating a comprehensive list of any pathogens reported in dogs, including bacteria, parasites, fungi and viruses. The list was then pared down to those significant to Canada and the Prairies, using a collaborative prioritization exercise with experts in the field of veterinary medicine, public health and epidemiology. The research team identified the five highest priority pathogens from a final list of 84 canine pathogens upon which to focus their surveillance program.

Next, Sims examined the role of clinical veterinarians and veterinary clinics in the surveillance program. Results showed that clinical veterinarians are willing to participate, and from a disease monitoring standpoint, important in-clinic veterinary data is not being captured. Through this work, the researchers determined domestic dogs can serve as a good warning for Lyme disease risk in humans, specific to the Prairies.

Sims also identified which dog-related pathogens pose a significant public health risk in Canada and the Prairies and prioritized these pathogens from highest to lowest concern using expert opinion. The study’s results established the importance of co-operation with practicing veterinarians and veterinary clinics for a companion animal surveillance program to be successful.

Read more about Sims' research project on WCVM Today.

  • Supervisor: Dr. Cheryl Waldner, Department of Large Animal Clinical Sciences, WCVM
  • Thesis title: “Agent-based modelling to address emerging threats from antimicrobial resistance to the sustainability of the beef industry.”
  • Click here to read thesis

Snapshot

Antimicrobial resistance (AMR) is a global public health concern for human and animal health, and rising AMR has increased scrutiny of antimicrobial use in feedlot cattle. Metaphylactic use, or routinely medicating a group of animals to prevent disease occurrence when an outbreak is expected, is a common practice for high-risk cattle at feedlot entry. The impact of transmission of resistant microorganisms and/or the genes encoding for resistance hasn’t been fully investigated in feedlot cattle.

Thompson developed a computer model and used a technique called agent-based modelling to explore the emergence and transmission of AMR among feedlot cattle. By running simulations using a dynamic model, researchers can explore the effectiveness of potential interventions without the expense or possible adverse consequences of implementing new interventions in the real world.

After developing the model, Thompson created two separate experiments. The first investigated the influence of on-arrival injectable antibiotic options on AMR in feedlot cattle and tested how resistant two types of bacteria were to three different types of antimicrobials used for on-arrival metaphylaxis at feedlots. The bacteria causing bovine respiratory disease (BRD) showed less resistance to antimicrobials in the animals that received on-arrival metaphylaxis when compared to none, but only when the BRD treatment differed from the preventive therapy. These results suggest that the on-arrival metaphylaxis causes a reduced need to treat animals in response to infections, which creates less opportunity for resistance to form in the BRD-causing bacteria. Preventive use of the antimicrobials could also potentially minimize resistance to other more medically important drugs used for treating BRD, when compared to no preventive drugs used on arrival.

The second experiment explored the transmission of resistant genes and mutations through animal-to-animal contact and contact with fecal contamination of the environment. The computer model successfully replicated previously observed resistance prevalence for M. haemolytica and E. coli in a typical western Canadian feedlot assuming selection due to antimicrobial use, transmission of antimicrobial resistance and a combination of both. The potential importance of transmission of AMR directly from animal to animal or through the environment must be considered when evaluating expected benefits to antimicrobial stewardship efforts.

If on-arrival metaphylactic AMU in high-risk calves was eliminated without suitable health management alternatives, it could result in greater disease incidence and subsequently higher use of medically important antimicrobials for therapeutic treatment. Therefore, the research suggests that metaphylaxis is warranted to reduce disease incidence throughout the feeding period. But metaphylaxis should use products that have lower importance to human medicine to minimize the potential public health impact since researchers saw an increase in resistance prevalence within the same drug class as the antimicrobial drug administered for metaphylaxis.

 

  • Supervisor: Dr. Yolande Seddon, Department of Large Animal Clinical Sciences, WCVM
  • Thesis title: “Motivated for movement? Exercise and the gestation environment on sow performance and welfare.”
  • Click here to read thesis

Snapshot

The current Canadian Code of Practice for the Care and Handling of Pigs permits operating existing stall barns if pregnant female pigs are given access to periodic exercise. The goal of this research was to determine how motivated the female pigs are to spend time out of their stall, and to determine whether periodic exercise can increase sow welfare and reduce stress in comparison to housing in stalls and groups throughout gestation.

Tokareva first compared motivation for movement and food using an operant panel, a device that determines the strength of an animal’s motivation by allowing it to make a choice that triggers a reward. The research team then fed sows differing amounts of feed and used operant panel testing to compare sows’ motivation to exit the stall.  Finally, they compared the welfare and productivity of the gestating sows that exercised versus those housed in in stalls and groups during pregnancy.

Both gilts (female pigs that haven’t produced a litter) and sows demonstrated equal motivation to exit the stall, with sows more motivated for food than the gilts. Feed-restricted sows were more motivated for movement, and group-housed sows lay more, sat less and performed fewer stereotypies than sows housed in stalls or given exercise.

The study’s results suggest gestating female pigs are motivated for movement, which has a strong exploratory/foraging component. While group housing improved sow comfort and reduced stress, periodic exercise only improved reproductive performance in older sows. Tokareva concluded that low levels of periodic exercise didn’t provide any welfare or production benefits and advised a transition to group housing rather than gestation stalls.   

Veterinary Pathology

  • Supervisor: Dr. Melissa Meachem, Department of Veterinary Pathology, WCVM
  • Thesis title: “Evaluation of nesfatin-1 expression in lean, overweight and diabetic cats.”
  • Click here to read thesis

Snapshot

Rates of obesity and diabetes mellitus are increasing in domestic cats. Diabetes mellitus is a disease of the pancreas, which causes the body to no longer regulate blood sugar. In cats, this typically results in increased thirst, increased urination, weight loss and increased appetite. Nesfatin-1 is a protein hormone implicated in controlling food intake and maintaining glycemic control. So far, no one has evaluated the protein’s role in the pathophysiology of obesity and diabetes mellitus in cats. 

The study aimed to characterize nesfatin-1 mRNA expression in feline tissue of cats and to evaluate how the protein’s expression differs between lean, overweight and diabetic cats.

Toh’s results suggest that changes in plasma nesfatin-1 concentrations may be more related to diabetic status and the presence of insulin resistance as opposed to differences in fatness or body condition, though further research is required to determine the significance of this relationship. There may be additional, currently unknown factors that increase nesfatin-1 concentrations in cats. Future studies may include extended studies to investigate if nesfatin-1 concentrations change as cats become obese, develop insulin resistance, and eventually become clinically diabetic.

  • Supervisor: Dr. Bruce Wobeser, Department of Veterinary Pathology, WCVM
  • Thesis title: “IIB or not IIB: Endometrial biopsy evaluation in horses using the Kenney-Doig scale.”
  • Click here to read thesis

Snapshot

The Kenney-Doig scale is the standard test used in equine theriogenology (reproduction). Introduced in the 1980s, veterinary pathologists use this scale to evaluate equine endometrial biopsies — a common test for assessing a mare’s fertility and her chances of having a healthy, live foal. However, the descriptive modifiers, or classifications of “absent,” “mild,” “moderate,” or “severe” used for the scale are potentially subjective and may not produce repeatable results.

The study focused on the level of agreement between veterinary pathologists when using the Kenney-Doig scale. To test the specialists’ conformity, the WCVM researchers gave the same endometrial samples to different pathologists and asked them to grade the samples using the scale.

The Kenney-Doig scale rates a mare’s ability to carry a live, healthy foal on four levels. Westendorf performed a retrospective analysis of all equine endometrial submissions to the WCVM and Prairie Diagnostic Services between 1998 and 2018 and determined the grading distribution between the four levels. She then performed a retrospective literature review and included six different studies reporting Kenney-Doig grading distributions.

Westendorf found significant differences between the grading distribution found at WCVM/ Prairie Diagnostic Services and the distribution reported in the six studies. Through further analysis, Westendorf found significant differences in grading tendencies, suggesting the presence of observer variation. She then completed a prospective study of agreement between eight board-certified veterinary pathologists who blindly graded the same set of samples. This study’r results suggest the system may be unreliable and subject to significant variability between those conducting the test.

  • Supervisor: Dr. Susan Detmer, Department of Veterinary Pathology, WCVM
  • Thesis title: “Strain diversity of Borrelia burgdorferi and the mode of infection influence 1 variation in microscopic lesions in C3H/HeJ mice.”

Snapshot

Lyme disease is the most common vector-borne disease (transmitted by blood-feeding insects such as mosquitoes and ticks) in people and animals in the Northern Hemisphere. In eastern North America, Lyme disease is caused by the bacteria Borrelia burgdorferi sensu stricto (Bbss) and is transmitted by the black-legged tick. Populations of Bbss consist of different strains, which can cause the disease to present differently in its host.

Zvionow tested the presentation of Lyme disease in research mice by experimentally infecting them with one of three strains of Bbss: Bb16-198, Bb16-174 and Bb16-167. Infection was done by needle inoculation and tick bite, while the control group was infected by uninfected ticks or given a sham inoculation.

Ninety-four days after infection, the research team microscopically analyzed tissue samples. Lesions associated with infection by all three strains of Bbss were found in the animals’ ventral skin, kidney, tibiotarsal (joint connecting the shin and the foot) and arteries of the rear limb. Inflammation of the arteries near the tibiotarsal joint was more pronounced in mice infected with the Bb16-198 strain compared to the other two strains. Across the three strains, female mice had more severe lesions in the ventral skin compared to male mice. Future studies should investigate the difference between the sexes in the skin’s response to Bbss.

Toxicology

  • Supervisor: Dr. Steven Siciliano, USask College of Agriculture and Bioresources
  • Thesis title: “Benzene oral bioavailability assessment using in vitro digestion model in combination with cell culture methodology.”
  • Click here to read thesis

Snapshot

Volatile organic compounds (VOCs) include a variety of chemicals, some of which may have short- and long-term adverse health effects. They are emitted as gases from certain solids or liquids. The bioavailability, or the rate at which VOCs enter circulation, is challenging to assess, and the lack of standard methods for introducing VOCs into in vitro bioassays — a testing method for measuring the effect of a substance on living cells — can lead to poorly defined bioavailable concentrations. 

As a result, in vitro tests normally conducted in wells of cell culture plates for risk assessment of volatile and hydrophobic organic chemicals (VHOCs) have always faced significant experimental difficulties due to high volatility (change to a vapour state) and high water resistance (hydrophobicity). This compromises the test’s true amount of substance by causing it to decline in the test medium. It also limits the quality of the toxocological response and the understanding of them.

The researcher developed a dosing method to assess the bioavailability of benzene — a model for VHOCs — in aqueous tests and to better characterize exposure estimates for an improved risk assessment during in vitro biotests. This study introduces an effective approach to passive dosing and demonstrates the use of passive dosing over solvent spiking for in vitro toxicity testing of hydrophobic chemicals with high volatility. 

This has fundamental implications for a better understanding of the interactions between VHOCs’ exposure to humans and the toxic effects on the human intestine to help set remediation objectives and to further improve future risk assessment and standard setting for VHOCs.

  • Supervisor: Dr. David Janz, Department of Veterinary Biomedical Sciences, WCVM
  • Thesis title: “Differential selenium uptake by periphyton in boreal lake ecosystems.”
  • Click here to read thesis

Snapshot

Selenium is a naturally occurring trace element with a narrow margin between essentiality and toxicity in many organisms. It’s a contaminant of concern in North America’s boreal forest region because certain human activities increase the loading of selenium into cold-water aquatic ecosystems, which can have adverse effects on species such as fish, amphibians and birds. The element is rapidly and efficiently assimilated from water into organisms and transferred to larger species that consume them — a process that isn’t well understood.

Complex networks of algae, bacteria, fungi and detritus known as periphyton live at the bottom of the water and play a key role in incorporating selenium into more harmful organic forms. Due to site-specific differences in incorporating the element into the aquatic food web, it’s difficult to predict the ecotoxicological effects of increased selenium loading into the environment.

Most studies focused on the ecological risk assessment of selenium have been conducted in warm-water systems, and more research is needed on the effects of increased selenium loading in cold freshwater ecosystems. Boreal lakes can be at greater risk to selenium toxicity due to the low presence of other compounds such as sulfate and phosphate, which have been known to interfere with selenium uptake by organisms.

This study’s goals were to address research gaps to better understand how organisms assimilated selenium. The trends demonstrated by different water chemistry and periphyton community variables among multiple boreal lakes could serve as representative factors to consider when assessing potential risks of selenium toxicity in different freshwater lakes and ponds. Research results provide further insight on the biodynamics of selenium assimilation at the base of boreal lake food webs at environmentally relevant concentrations, which can potentially inform selenium ecological risk assessments in cold, freshwater ecosystems in North America.

  • Supervisor: Dr. Christy Morrisey, USask College of Arts and Science
  • Thesis title: “Role of vegetated buffer zones for mitigating wetland pesticide contamination and protecting aquatic invertebrate communities in northern prairie wetlands.”
  • Click here to read thesis

Snapshot

The Prairie Pothole Region (PPR) is made up of millions of shallow pools left behind by glaciers during the last ice age, spanning southern Alberta, Saskatchewan, Manitoba and extending into North Dakota, South Dakota, Iowa, Minnesota and Montana. The PPR wetlands are a unique resource that provide a number of benefits to the surrounding ecosystem. However, most of these wetlands have been drained or degraded by agricultural activities.

PPR wetlands are frequently contaminated by agrochemicals from surrounding agriculture, which has previously demonstrated to have negative impacts on wetland ecology. Vegetation buffers have been proven to be effective in mitigating pesticide and nutrient contamination of water bodies, but no one has studied their efficacy in protecting PPR wetlands.

Wade examined how multiple agricultural stressors affect PPR wetland health and whether natural wetland vegetation or producer-implemented perennial plantings are effective buffers that can mitigate some of the negative effects of agriculture. The research methods included measuring pesticides, nutrients and water quality, as well as studying aquatic invertebrate populations in order to evaluate the health of selected PPR wetlands.

Presence of the buffers significantly associated with greater abundances of aquatic life and insects, which may benefit the many wildlife species that depend on wetland invertebrate productivity for food. This work establishes a framework for using wetland invertebrate communities as an integrative biomonitoring tool for assessing effects of complex agricultural stressors to PPR wetlands.

Results demonstrate negative effects of multiple agricultural stressors on wetland health, as measured by changes in the aquatic invertebrate community. These findings suggest that leaving or planting wetland vegetation around PPR wetlands could increase community richness and abundance of beneficial insects, but it’s not sufficient for protecting wetlands from pesticide contamination.

However, surrounding wetlands with perennial vegetation plantings in addition to other natural vegetation could reduce pesticide and nutrient contamination of wetlands and increase the abundance and diversity of aquatic invertebrates. These findings may help guide producers and land managers who are motivated to improve wetland health and ecosystem services in prairie agricultural landscapes.

  • Supervisors: Dr. George Graham and Dr. Ingrid Pickering, USask College of Arts and Science; Dr. Patrick Krone, USask College of Medicine

  • Thesis title: "Accumulation, distribution and chemical form of organic mercury in brain tissue and larval zebrafish (Danio rerio)."

Thesis under embargo.

Certificates

  • Fernando de Paula Freitas
  • Alexandra Paige Focken
  • Olivia Montgomery Saunders
  • Go Togawa
  • Tsung Han Tu
  • Sheena Wing Sze Wong
  • Alexandra Frey Belotta, medical imaging
  • Danica Rianne Lucyshyn, ophthalmology
  • Cheyenne Nadbrzezna, avian, exotic and wildlife medicine and surgery
  • Mathieu Victor Paulin, small animal internal medicine
  • Upkardeep Singh Pandher