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Assessing effects and fate of environmental contaminants in invasive, native, and endangered macrophytes

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Creator (cre): Sesin, Verena, Thesis advisor (ths): Freeland, Joanna R, Thesis advisor (ths): Davy, Christina M, Degree committee member (dgc): Gilbert, Janice M, Degree granting institution (dgg): Trent University
Abstract:

Macrophytes play an important role in aquatic ecosystems, and thus are integral to ecological risk assessments of environmental contaminants. In this dissertation, I address gaps in the assessments of contaminant fate and effects in macrophytes, with focus on glyphosate herbicide use for invasive plant control. First, I evaluated the suitability of Typha as future standard test species to represent emergent macrophytes in risk assessments. I concluded that Typha is ecologically relevant, straight-forward to grow, and its sensitivity can be assessed with various morphological and physiological endpoints. Second, I assessed effects from glyphosate (Roundup WeatherMAX® formulation) spray drift exposure on emergent non-target macrophytes. I performed toxicity tests with five taxa, Phragmites australis, Typha × glauca, Typha latifolia, Ammannia robusta, and Sida hermaphrodita, which in Canada collectively represent invasive, native, and endangered species. I found significant differences in glyphosate sensitivity among genera, and all species' growth was adversely affected at concentrations as low as 0.1% (0.54 g/L), much below the currently used rate (5%, 27 g/L). Third, I assessed the potential for glyphosate accumulation in and release from treated plant tissues. I found that P. australis and T. × glauca accumulate glyphosate following spray treatment, and that accumulated glyphosate can leach out of treated plant tissues upon their submergence in water. Finally, I assessed effects of released glyphosate on non-target macrophytes. I found that P. australis and T. × glauca leachate containing glyphosate residues can stimulate the germination and seedling growth of T. latifolia, but can exert an inhibiting effect on A. robusta, although leachate without glyphosate caused similar responses in both plants. Additionally, I found no negative effects in A. robusta when exposed to glyphosate residues in surface water, or when grown with rhizosphere contact to an invasive plant that was wicked (touched) with glyphosate. My results show that non-target macrophytes can be at risk from glyphosate spray for invasive plant control, but risks can be mitigated through informed ecosystem management activities, such as targeted wick-applications or removing plant litter. Integrating contaminant fate and effect assessments with emergent macrophytes into ecological risk assessments can support the protection of diverse macrophyte communities.

Author Keywords: Ecosystem management, Ecotoxicology, Glyphosate, Herbicide, Invasive plant, Species at risk

2021

Robust assessment of changes in wild mammal occupancy and activity relative to livestock and human disturbance

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Creator (cre): Scott, Carly Marie, Thesis advisor (ths): Murray, Dennis L, Thesis advisor (ths): Thornton, Daniel H, Degree committee member (dgc): Beresford, David V, Degree granting institution (dgg): Trent University
Abstract:

Anthropogenic activities such as human activity and livestock grazing are responsible for the global rise in disturbance impacts on wildlife and may underlie regional changes in biodiversity and ecosystem dynamics. Few studies have tried to disentangle the effects of different anthropogenic activities on wildlife behaviour, leaving a major gap in our understanding of conservation and management needs in disturbed areas. Human activity and livestock grazing are increasing in spread and intensity worldwide, thereby imposing pressure on both wildlife and natural areas. In this thesis, I used a camera trapping and occupancy modeling framework to assess whether human presence and livestock grazing had different impacts on site occupancy and activity of 10 wild mammal species, and how responses differed across taxa. Specifically, I predicted that all species would be sensitive to disturbance, but the type and intensity of the response would depend on disturbance type. I detected different responses to each disturbance type across species, but response type (displacement, activity change, crepuscularity) was not associated with species characteristics such as body. Importantly, disturbance intensity had a strong effect on wildlife activity levels, with many species exhibiting marked reductions in activity at high human or livestock disturbance intensity. It remains unclear whether all species' responses are a direct consequence of disturbance versus indirect outcomes of shifts in behaviour of other species in the wildlife community (i.e., disturbance-related changes in prey activity may affect predator activity). Although on the whole disturbance intensity and effect sizes tended to be relatively low in this study, responses were exhibited across all species, implying that disturbance responses may be universal in wild mammals and largely underestimated. Ultimately, my work offers a template for the robust assessment of disturbance impacts on wildlife and provides new avenues for future research to deepen our understanding of wildlife sensitivity to anthropogenic activities.

Author Keywords: activity, anthropogenic disturbance, human activity, livestock, occupancy, wildlife

2021

Evidence of an Interaction Between Memory Stores for Long-Term Context Fear Memory in the Rat

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Creator (cre): Roberts, Kassidy, Thesis advisor (ths): Lehmann, Hugo, Degree committee member (dgc): Fournier, Neil M, Degree committee member (dgc): Sparks, Fraser T, Degree granting institution (dgg): Trent University
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Memories which typically require the hippocampus (HPC) can become represented in structures outside of the HPC, and therefore resistant to HPC damage, but, the properties of these memories are poorly understood. Some research has suggested that the HPC continually contributes to memories that are resistant to hippocampal damage, and without this support, they are weaker and more susceptible to loss. However, this hypothesis has yet to be tested experimentally. We examined this possibility in rats by assessing decay and extinction of a context fear memory that had become independent of the HPC via repeated learning episodes. We found that HPC-independent context fear memories decay and extinguish faster without continued HPC support, suggesting that the HPC plays a continued role in long-term memory. We also provide new evidence of a persistent interaction between the HPC and other memory systems, which strengthens non-HPC representations so that they withstand HPC damage at longer intervals.

Author Keywords: consolidation, context fear, hippocampus, memory, retrograde amnesia

2022

Desire to be Zine: Feminist Zine Culture and Materiality in the Digital Age

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Creator (cre): Rayner, Sarah, Thesis advisor (ths): Epp, Michael, Degree committee member (dgc): McGuire, Kelly, Degree granting institution (dgg): Trent University
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This thesis explores access to feminist zine culture and community, specifically if, and how, access has been altered in the age of digital technologies and increased access to digital spaces. Results from a questionnaire completed by 8 young feminist zine-makers and readers of marginalized genders indicated that though the modern boundaries of what a zine is has been expanded to include e-zines, there remains a preference toward print zines in zine-making and reading practices. Results also revealed that while there is a preference toward accessing feminist zine culture and community in-person in theory, participants were more likely to access feminist zine culture and community online in reality. This project found that digital technologies and the Internet have affected feminist zine culture in multiple ways, ranging from the Internet creating a new access points to community, to the Internet making it easier to find, purchase, and distribute zines.

Author Keywords: Digital Media, Feminism, Feminist Zine Culture, Feminist Zines, Materiality, Print Media

2021

Peers, Props & Play: Complexity of Pretend Play and Early Academic Skills

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Creator (cre): Pascoe, Paige, Thesis advisor (ths): Im-Bolter, Nancie, Degree committee member (dgc): Eastabrook, Jennifer, Degree committee member (dgc): Agostino, Alba, Degree granting institution (dgg): Trent University
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This study examined the relation between complexity of pretend play during preschool and early academic skills two years later. Preschool children (n =19), aged 3 years, were observed during self-directed free play, which was then coded for complexity of symbolic thought with respect to symbolic agent (ability to direct self or other's play) and symbolic substitution (abstractness of props). Children's literacy and numeracy skills were assessed concurrently and two years later when children were 5 years old. We found that children who directed others' play compared to children who focused on their own play had higher mathematics achievement at 5 years. In addition, children who engaged in more complex object substitutions (abstract props) had better counting at 3 years and better early reading skills at 5 years than their peers, who showed few complex substitutions. Our findings suggest that encouraging specific aspects of pretend play in preschool could be a relatively simple way to promote early academic achievement.

Author Keywords: Math , Play complexity, Preschool , Pretend Play, Reading

2021

Drink my beer, smoke my weed, my good friends are all I need: Attachment representations and substance use in an university sample

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Creator (cre): Robertshaw, Ashley, Thesis advisor (ths): Eastabrook, Jennifer, Thesis advisor (ths): Im-Bolter, Nancie, Degree committee member (dgc): Smith-Chant, Brenda, Degree granting institution (dgg): Trent University
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Past research has predominately supported an association between insecure attachment and substance use. More recent research has found that while individuals with secure attachment may use substances, they do so with less risk. The current study attempted to replicate the finding regarding secure attachment and substance use and examined the motivational drives behind why students use substances. A total of 318 undergraduate students completed self-report questionnaires examining peer attachment, alcohol and marijuana use, as well as motivations for use. Results indicated that students who reported low frequency use of alcohol or marijuana did not have significantly higher security ratings compared to students who reported increased use. Additionally, although hypothesized, secure attachment ratings were not associated with social facilitation or enhancement motivations. However, fearful and dismissing attachment ratings were both significantly associated with coping motives as predicted, while preoccupied and fearful attachment ratings were significantly associated with conformity motives. Lastly, results from multiple regressions suggest that coping and enhancement motivations are significant predictors of alcohol use, while enhancement motivations are marginally significant in predicting marijuana use.

Author Keywords: alcohol, attachment, marijuana, motivation

2021

Calcium Stress in Daphnia Pulicaria and Exposure to Predator-Derived Cues: Making a Bad Situation Worse?

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Creator (cre): Rice, Marcus James, Thesis advisor (ths): Frost, Paul P. C., Degree committee member (dgc): Paterson, Michael M.P., Degree committee member (dgc): Beresford, David D.B., Degree granting institution (dgg): Trent University
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In recent decades, declining calcium concentrations have been reported throughout lakes across the southern edge of the Canadian Shield. This raises concern as Daphnia populations have shown to be decreasing as they require calcium not only for survival but to mitigate predation risks. Therefore, the purpose of my thesis was to study the adaptability of Daphnia under calcium limitation and predation risk from Chaoborus. Firstly, I examined the effects of calcium limitation and Chaobours kairomones on daphniid life-history and population growth. I found that low calcium concentrations and Chaoborus kairomones affected Daphnia calcium content, life-history traits, and survival. Next, I focused on how calcium concentrations and Chaoborus abundance affected the calcium content and abundance of daphniids. During this study, I also examined the relationship between the abundance of Daphnia and a competitor Holopedium. I found that calcium concentrations and the abundance of Chaoborus affects daphniid abundance. Overall, results from this study show the importance of considering both predation risk and calcium declines to better determine daphniid losses.

Author Keywords: anti-predator responses, Chaoborus, competition , Life-History traits, predator cues, Zooplankton

2021

An Exploration of Partnership Models for Urban Conservation Land Management in Ontario

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Creator (cre): Radcliffe, Dylan, Thesis advisor (ths): Whillans, Tom, Degree committee member (dgc): Attridge, Ian, Degree granting institution (dgg): Trent University
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Partnerships for management of public parks have a long history, but little attention has been given to the current models of partnerships during a period of municipal austerity in Ontario. Using a qualitative assessment of transcripts from representatives of 10 municipal partner groups, this research considers what some of the current models are, the impact that they may have, and how municipalities may foster these partnership arrangements. The participating organizations demonstrated that their governance models evolved to suit their mandate, activities, and scope of interaction with their municipality. Additionally, this research corroborates past findings that efficacy of an organization is tied to their ability to partner with other agencies and act as a capacity amplifier. These results demonstrate how municipal conservation partnerships can be effectively applied to create enhanced financial outcomes and improved community engagement, while delivering community based environmental programming.

Author Keywords: Conservation, Environmental Stewardship, Municipal Management, Partnership, Social Ecology, Urban Parks

2020

Morphology, Production and Trade: An Investigation of African Export Amphoras in the Mid-Roman Imperial Period

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Creator (cre): Racine, Karl, Thesis advisor (ths): P. Moore, Jennifer J. P. M., Degree committee member (dgc): Elton, Hugh H. E., Degree committee member (dgc): Conolly, James J. C., Degree committee member (dgc): Stone, David D. S., Degree granting institution (dgg): Trent University
Abstract:

The Africana IIA, an amphora subtype of the Africana II class, was produced in Africa Proconsularis (the present-day Tunisian Sahel) during the mid-Roman Imperial period (from the late 2nd c. A.D. to the middle decades of the 3rd c. A.D.), and was distributed around the western Mediterranean. Scholars have noted meaningful morphological variations on this subtype's rim but had overlooked the information that these rims may convey. The preliminary analysis of the variations found on Africana IIA amphora rims yielded possible connections to various production sites or regions, distribution samples, and/or consumption sites, and suggested that at least some of the rim variants were indicative of origin. The rim variants also seemed to correlate to different trade routes, and potentially, different trade mechanisms, including private versus State interests.

Author Keywords: Africa Proconsularis, Africana IIA amphora, ancient economy, Byzacena, ceramics, fabric analysis

2021

Developing Social-Emotional Competencies in Youth: Validation of the Short Form for the Emotional Quotient Inventory Youth Version (EQ-i:YV-S)

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Creator (cre): Storey, Emily, Thesis advisor (ths): Parker, James, Degree committee member (dgc): Summerfeldt, Laura, Degree granting institution (dgg): Trent University
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Trait Emotional Intelligence (TEI) plays an important role in the health and wellness of children and adolescents. Not surprisingly, the literature on TEI and youth has expanded dramatically. Although the quality of this work continues to be uneven due to the continued proliferation of TEI-related measures with questionable psychometric features. One over-looked TEI measure in the field is the short form developed for the Emotional Quotient Inventory Youth Version (EQ-i:YV-S). The core goal of Study 1 was to examine the overall reliability and validity of the EQ-i:YV-S. The aim of Study 2 was to evaluate the utility of the EQ-i:YV-S as a measure of the effectiveness of a new school-based social and emotional learning program for elementary school students. Results from Study 1 demonstrated that the EQ-i:YV-S had good internal reliability, 6-month test-retest reliability, and convergent validity. Study 2 found that Total EI and most key EI-related dimensions had significant improvement from pretest to post test on the EQ-i:YV-S. These findings have important implications for TEI measurement in youth and the effectiveness of school-based psychoeducational programming for TEI, with the EQ-i:YV-S as a viable option for research in this area.

Author Keywords: emotional intelligence, psychoeducational programming, social-emotional competencies

2021