Environmental and Life Sciences

The Great Lakes represent nearly a fifth of the global freshwater surface supply, and support culturally, economically, and ecologically important fish species such as Walleye (Sander vitreus). With water temperatures projected to rise by several degrees in the coming century, understanding the energetic impacts on fishes is crucial for effective habitat and fisheries management. I measured the swimming performance, accelerometer-based activity, and metabolism of walleye in relation to body size, sex, and water temperature to assess potential responses to climate variability. Both acceleration and swim speed predicted metabolic rate with reasonable accuracy. Temperature had a positive effect on oxygen consumption whereas body mass had a negative effect. Critical swimming speed increased with temperature, and tailbeat frequency had positive relationships with swim speed and acceleration. My laboratory-based calibrations should enable remote field monitoring of energy use of walleye (via accelerometers) and help conserve an important species through bioenergetic modelling.

Author Keywords: accelerometry, bioenergetics, climate change, metabolism, respirometry, walleye

In Ontario, farmers commonly use a MZ (Maize (Zea mays L.))-SB (Soybean (Glycine max))/WW (Winter wheat (Triticum aestivum)) – CC (mixed cover crop) rotation to maximize economic benefits. This study aimed to investigate the short-term impacts of the crop rotation phases and their associated management practices in this diversified cash crop rotation on soil health and the abundance of nitrogen (N)-cycling soil microbial communities (SMCs). Additionally, the abundance of N-cycling SMCs and plant-available N in both surface (0-5 cm) and rooting zone (5-15 cm) depths were characterized in tile-drained (TD) and non-TD fields. In the present study, soils collected under the CC phase had the highest labile carbon levels (10-17% higher) and water-stable aggregates (35-50% higher) compared to the other two crop phases. Lower nitrifying (amoA) gene abundances and soil NO3--N levels were observed in the CC phase compared to the MZ and SB-WW phases, suggesting a potential for decreased nitrification in the CC phase. The presence of SB potentially influenced the soil N concentration in the subsequent WW phase likely due to the release of symbiotically fixed N in the SB-WW phase. Further, higher amoA abundances and NO3--N in the SB-WW phase imply a potential for increased nitrification in the SB-WW phase. Additionally, higher amoA/nosZI and nirS+nirK/nosZI ratios were observed in the MZ phase than in SB-WW and CC phases, suggesting a potential capacity for increased N2O emissions from the reactions mediated by N-cycling SMCs in soils planted to MZ during fall sampling days. In the TD and NTD field study, higher NO3--N levels were observed in TD-SB-WW fields at 5-15 cm vs. 0-5 cm depths, which was possibly facilitated by tile drainage. The TD-CC fields displayed higher nosZI gene abundances and lower nirS+nirK/nosZI abundance ratios, suggesting a greater potential capacity for decreased N2O emissions in soils planted to CCs during the spring sampling days. When examining changes in plant available N by soil depth, reduced downward movement of NO3- through shallow soil depths (0-15 cm depth) was observed in the CC phase compared to cash crops. This short-term study highlights the potential contribution of the CC phase, particularly within TD agricultural fields, for improving soil health and reducing potential N2O emissions. Together, these results suggest that management-associated differences in crop rotation phases have temporary effects on soil health and the abundance of SMCs. Future studies linking N-cycling SMC's potential activity and field-scale N2O fluxes will provide a better insight into the longer-term sustainability of Ontario's cash crop management systems.

Author Keywords: denitrification, maize-soybean-winter wheat- cover crop rotation, nitrification, soil depth, Sustainable agriculture, tile-drainage

The detection of ciguatoxins (CTXs) in biological samples is challenging due to their low concentrations, the presence of various congeners, and the absence of standardized methods. This study uses high resolution mass spectrometry (HRMS) with P-CTX-3B as a reference standard. The protonated molecules ([M+H]+) were most prevalent, especially when acetonitrile/water was utilized, providing enhanced sensitivity. Optimized collision energies of 15 eV for protonated molecules and flow rates of 10 µl/min enhance sensitivity and peak intensities, respectively. Acetonitrile/water (ACN/H2O) is recommended as the primary solvent for HRMS method, an aspect underexplored in existing literature. The detection of CTX-3B in fish tissue samples proved to be challenging, caused by variations in ion peak intensities and matrix effects, requiring a deeper exploration of the impact of complex matrices on CTX detection. The study emphasizes the need for a reliable internal standard to mitigate these effects and highlights the ongoing challenge of developing a rapid, simple, and sensitive detection method. The study's specific focus on the P-CTX-3B analogue significantly contributes to methodology development for this congener, serving as a foundational step in understanding and detecting CTX. Despite notable progress, the study acknowledges the absence of an ideal assay, outlining key challenges for future research on ciguatera analysis. It underscores the continuous necessity for method reevaluation, testing, and the broader goal of establishing a more clarified and rugged method for the identification of CTX in fish.

Author Keywords: Analytical Chemistry, Ciguatera Fish Poisoning, Ciguatoxin, High-Resolution Mass Spectrometry, Optimization, P-CTX-3B

Northern flying squirrels (NFS) are mycophagous specialists (fungi-dominated diet) thatmay be displaced with southern flying squirrel (SFS) range expansion, thereby limiting fungal dispersal in forest communities. To understand the implications of squirrel species turnover on mycophagy, we investigated the home ranges of both flying squirrel species who are living in stable sympatry. We found no significant difference in home range sizes and identified spatial overlap between the two species. Through habitat selection ratios we found SFS were strongly selecting for deciduous-dominated habitats more than NFS. Lastly, we conducted microscopy on flying squirrel scat and found NFS were eating more fungi than SFS. We conclude that the squirrels are sharing the same habitat landscape but are finding ways to partition the habitat accordingly to allow for sympatry. SFS may contribute to the spore-dispersal cycle similarly to their northern counterpart through moderate fungus consumption and large home range sizes.

Author Keywords: diet, flying squirrels, Glaucomys, home range, mycophagy, sympatry

Climate change is a major conservation concern, especially for many cold-adapted species. The rate of warming due to climate change will likely outpace adaptive responses, and many populations will likely need to rely on phenotypic plasticity to cope with environmental warming. It is currently unclear whether plasticity in physiological responses to warming will be sufficient to offset the negative consequences of chronic environmental warming in ectotherms. I studied within-generation and transgenerational plasticity in two cold-adapted species of fishes, lake trout (Salvelinus namaycush) and brook trout (S. fontinalis), following temperature acclimation. Adults of both species were acclimated to either cold or warm temperatures and offspring were generated using a fully factorial breeding design, whereby the family thermal histories included crosses made within each temperature treatment and bidirectional crosses between temperatures. Offspring families were subdivided into two groups and acclimated to either warm or cold temperatures, so that offspring thermal experience matched or mismatched that of one or both parents. Offspring metabolic rate and critical thermal maximum during an acute thermal challenge were measured for both species. Limited transgenerational plasticity was detected in both species, but had a lesser effect than within-generationacclimation. In brook trout, the paternal contribution was greater than the maternal contribution. In lake trout, a mismatch in thermal acclimation, where the offspring were cold-acclimated but the parents warm-acclimated, resulted in elevated offspring metabolic rate without a corresponding increase in growth, suggesting that a mismatch in temperatures across generations could be detrimental to offspring. Using RNA-sequencing, transgenerational plasticity was linked to differential gene expression in the liver of lake trout offspring, in that genes were differentially expressed depending on the parental acclimation temperatures. Within-generation warm acclimation had the greatest effect on gene expression profile of offspring, with more genes differentially expressed under conditions of within-generation warm acclimation compared with transgenerational warm acclimation. Although it has been suggested that transgenerational plasticity may help to buffer the impact of warming due to climate change, my work implies that transgenerational plasticity, like within-generation plasticity, will be insufficient for these two species of cold-adapted salmonids to cope with climate change.

Author Keywords: Brook trout, Climate change, Lake trout, Phenotypic plasticity, Thermal tolerance, Transgenerational plasticity

The Wabigoon River is known for an historic mercury (Hg) pollution source, caused by a chlor-alkali facility operating in the 1960s. As legacy Hg contamination continues to cause serious adverse health effects to the local communities living in the Wabigoon River region, it is imperative to undertake additional research to understand the deposition and transport of historical mercury in this system and more importantly, its conversion into methylmercury (MMHg) which renders it bioavailable for ongoing bioaccumulation. The aim of this dissertation was to evaluate the transport and accumulation of Hg species by doing a spatial and temporal analysis of concentrations of mercury and methylmercury along the Wabigoon River, as well as assessing rates of methylation and demethylation, identifying areas of higher methylmercury production. Results show that locations downstream from the pollution source still show elevated mercury concentrations, with levels at least five times higher in water and up to 134 times higher in sediments compared to background levels. Among selected study sites, the Hydroelectric dam, the Wabigoon Rapids wetland and Clay Lake were identified to have high capacity for methylmercury production in the system, with notably Clay Lake presenting a higher potential for methylmercury accumulation due to the observed lower methylmercury demethylation rate. Furthermore, the impact of wetting and drying cycles on Hg methylation in riverbed and wetland locations within the Wabigoon River system was investigated through a laboratory simulation. Findings indicated increased susceptibility of riverbed locations to wetting and drying cycles.

Author Keywords: Demethylation, Mercury, Methylation, Methylmercury, Wabigoon River

Access to human blood for forensic research and training in bloodstain pattern analysis (BPA) can be difficult due to many ethical, safety and cost concerns. Mammalian blood alternatives can be sourced, especially from local and willing abattoirs, but some concerns remain, and the added difficulties of high variation and species-specific differences in cellular components pose other issues. Therefore, synthetic alternatives to human blood provide practical options for the BPA community. This thesis explores the use of alginate hydrogels as a base material for forensic blood substitute (FBS) development. Hydrogels are first explored as a suitable environment for DNA stability and functionality and compared to other polymer systems. The ability of DNA to remain intact while undergoing electrospray ionization (ESI) is also investigated. The FBS design focuses on mimicking the fluid properties and genetic capabilities of whole human blood – a material not developed in FBSs previously. ESI was used to develop microparticles (MPs) that serve as cellular components of human blood (the red blood cells – RBCs, and white blood cells – WBCs). The microparticles were ionically crosslinked using calcium to provide small MPs (RBCs) or covalently crosslinked with functional DNA to provide larger WBC-like functional particles. The integration of these novel MPs into alginate-based materials is optimized and their use in BPA scenarios is explored. The FBS is tested in BPA scenarios of dripping experiments, impact patterns, and the ability to extract and amplify the contained DNA. In addition, the stability (or shelf-life) of the FBS was also assessed. The FBS exhibited similar spreading ratios to blood and demonstrated feasibility in use for impact angle (a) determination and impact pattern creation. Importantly, the DNA contained within the FBS could be processed with analogous protocols used in DNA evidence processing, enhancing its applicability to BPA research and training.

Author Keywords: Alginate hydrogels, Bloodstain pattern analysis, Electrospray ionization, Forensic blood substitutes, Forensic materials, Synthetic DNA design

Objectives/purpose: This study examined the psychosocial health (including resilience, hope, social functioning, mental wellbeing, and stress) of childhood cancer patients attending a recreational oncology camp (ROC).Methods: Childhood cancer patients enrolled for ROC participated in a survey on the first (T1) and last (T2) day of camp, and 3 months post-camp (T3). This survey included the: Child and Youth Resilience Measure (CYRM), Children's Hope Scale (CHS), Social Provisions Scale (SPS-5), and Short Warwick-Edinburgh Mental Wellbeing Scale (SWEMWBS). Afternoon saliva samples were collected at T1 and T2 to determine cortisol (ELISA). Results: CYRM, SPS-5, and SWEMWBS scores were high but did not differ between timepoints. CHS scores at T3 were lower compared to T1 and T2 (F=9.388, p=0.008). Salivary cortisol levels were within normal ranges. Conclusion/clinical implications: Childhood cancer patients have high levels of positive psychosocial variables and normal stress levels while attending ROC.

Author Keywords: cancer, children, hope, oncology camp, psychosocial health

Acoustic communication is vital for mediating interactions between individuals and their environment. From echolocating bats to isolated rodent pups, ultrasonic vocalizations are a useful mechanism for producing localized and cryptic acoustic signals. Flying squirrels have been demonstrated to produce almost exclusively ultrasonic calls which is rare in both squirrels and mammals, though the significance of this acoustic range is unknown. To investigate the context of ultrasonic calls in these gliding mammals, I created phylogenetic comparative analyses to compare ecological and morphological traits against call frequencies. I found that nocturnality, a trait entangled with gliding in squirrels, was related to higher-frequency calls. Furthermore, by comparing all gliding mammals and their non-gliding counterparts, I found that gliding mammals produce significantly higher frequencies than these relatives. This form of cryptic communication is likely used to avoid predation, which was further supported by behavioural experiments wherein flying squirrels used significantly higher frequencies when predation risk increased. While high frequency communication was used by most gliders, I found that ultraviolet-induced photoluminescence, another potential form of crypsis, was strongly associated with nocturnality, with half of the tested gliding mammals showing evidence of this unique colouration. While ultrasonic vocalizations are widespread in echolocating bats and echonavigating mammals, I did not find evidence to support echonavigation in flying squirrels. Instead, I found that ultrasonic vocalizations are used in a variety of social contexts and during solitary foraging and exploration. These combined results demonstrate the unique ecological and evolutionary pressures acting on small-bodied, nocturnal gliding taxa and the resulting cryptic behaviours and communication.

Author Keywords: communication, flying squirrels, gliding mammals, Sciuridae, ultrasound, ultraviolet-induced photoluminescence

Fungi are a diverse group of organisms that play crucial roles in various ecological processes and have immense economic importance. Understanding the intricate mechanisms underlying fungal growth and development is fundamental to harnessing their potential and exploring their applications in different fields. Signalling molecules, such as hormones, have been identified as key regulators in fungal physiology, orchestrating intricate processes and modulating biological responses to the environment. Phytohormones, commonly associated with plants, have been proposed as potential myco-hormones due to their production in a wide variety of fungi. Metabolomic analyses were performed via LC-MS/MS to investigate the role of phytohormones, specifically cytokinins (CKs) and indole-3-acetic acid (IAA), along with lipids and energetic metabolites such as organic acids during the growth and development of the model fungus Sordaria macrospora. The results revealed a clear switch between CK ribosides and CK free bases during the ascosporegenesis stage, with increased levels of cZ and iP and decreased levels of iPR and cZR. A similar pattern was observed in the mutant strain smgpi1 but demonstrating higher levels of CK free bases and increased fruiting body formation compared to the wild type. These findings provide insights into the regulation of phytohormones especially during fungal fruiting body development. In terms of IAA, the levels increased during the transition to sexual development in all strains, with the per5 mutant, unable to produce lipids via the cytosol, demonstrating a higher concentration than the wild type. The interplay between energetic metabolites and IAA suggests a potential role in the transition to sexual development. Additionally, the dose-dependent effects of exogenous CK application were investigated, showing the potential of low concentrations, from 1 to 10 μM, of CKs in promoting biomass accumulation or sexual development. Furthermore, gene editing in S. macrospora was proposed as a future direction to explore the functions of CKs and other metabolites during fungal development. Overall, this research contributes to our understanding of phytohormone-mediated processes in fungi and opens avenues for future investigations in fungal biology.

Author Keywords: fungi, LC-MS, metabolomics, myco-hormone, phytohormone, sexual development