Using Variable Chlorophyll-a Fluorescence to Assess the Impact of Ocean Alkalinity Enhancement on the Photochemical Efficiency of Phytoplankton

Ocean Alkalinity Enhancement (OAE) is a potential carbon dioxide removal strategy to mitigate climate change by enhancing oceanic carbon uptake. This thesis contributes to the biological risk assessment of OAE by examining its effects on phytoplankton photophysiology through laboratory and field experiments. In vitro studies (Chapter 3) revealed species-specific responses to elevated pH (~8.7), with varying resilience among phytoplankton. Mesocosm experiments (Chapter 4) showed changes in beam attenuation, particle size distribution, and pH following magnesium hydroxide additions, but no clear biological responses. Similarly, field trials with brucite altered optical properties but did not impair photosynthetic function. However, scattering artifacts in bio-optical sensors affected chlorophyll-a fluorescence readings, emphasizing the need for careful methodological consideration. Instrument design influenced sensitivity to scattering, affecting data reliability. Overall, findings support existing evidence that OAE, when applied at appropriate scales, is unlikely to pose significant risks to marine phytoplankton but highlight challenges in measurement accuracy

Women on the Water: Perceptions of Human-Nature Relationships from Female Kelp Farmers in Maine and Atlantic Canada

Kelp farming has gained traction over the last few years in North America due to its environmental benefits and its unique gender-inclusivity within the world of aquaculture. This study uses a phenomenological and feminist framework to inductively explore how women in the kelp farming industry of Atlantic Canada and Maine perceive and experience their role in the industry, climate change, adaptation, and how these factors may influence their relationship with the natural world. It builds on previous research demonstrating how women tend to adapt to the effects of climate change differently than men. For the study I recruited seven female-identifying participants using news articles and social media platforms who then engaged in semi-structured interviews and a photovoice activity. The results suggest that participants prefer to approach climate change adaptation by looking to reach a new harmony with nature, rather than joining the ranks to ‘fight’ against climate change. This involves decentering modern human needs and instead balancing them against the needs of our natural environment. The data also explores how place-attachment affected participants’ psychology regarding their relationship with the natural world and climate change, as well as some of the challenges that the participants foresee for the kelp farming industry and their involvement in it

Anticipatory Locomotor Adjustments During Walking Over Unilateral Obstacles In Able-Bodied Participants

Walking control was assessed by investigating the changes in net joint power while going over unilateral obstacles placed in the plane of progression. Participants performed obstructed walking trials across seven different obstacle heights (0 to 60 cm) while kinematic and kinetic data were collected. Anticipatory locomotor adjustments (ALA) were observed in both crossing and supporting legs. Notably, there were significant adjustments in the supporting leg with the emergence of a plantar flexor energy generation phase, accompanied by an increase in hip extensors energy generation at the onset of the stance phase for higher obstacles. Furthermore, a complementarity in the power bursts of the crossing leg muscles was noted. Specifically, the left leg exhibited a greater pulling motion at the knee due to an enhanced knee flexor energy generation. This thesis contributes to a greater characterization of ALA to unilateral obstacles and provides some evidence about the complementarity of these adjustments

Carboniferous Sarcopterygian Fossils and the Marine Paleoenvironment of the Joggins Formation, Nova Scotia, Canada

Earth and Environmental Sciences Undergraduate Honours ThesisJoggins Fossil Cliffs, a UNESCO World Heritage Site in Nova Scotia, Canada, is known for its Late Carboniferous (Pennsylvanian) coal seams and remarkably preserved ecosystems that represent terrestrial tropical Pangea. Of the five formations present, the most significant is the Joggins Formation (Fm) which is divided into approximately 15 sedimentary cycles based on the alternation of flooding plains, coals, and channel bodies. While the site records cyclic terrestrial and marine deposits, the marine influence of the Joggins Fm has rarely been studied. As a result, many fish fossils in the Joggins Fm collection remain unidentified, and there are ongoing debates about the source of the marine influence. I aim to (1) identify five unidentified sarcopterygian fish fossils from the Joggins Fm, and (2) determine their habitat and depositional environment. I have selected seven sarcopterygian fish fossils, most of which are scales, and I identified them to the family level using relevant literature. To learn more about the marine influence at a specific location within the formation, a carbonaceous limestone was chosen as a representative specimen for the marine depositional environment based on its thickness and history of producing determinate fish fossils. Thin sections were made for a vertical representation of the limestone band as well as a sedimentary log for greater marine influence context. Both thin section and microfossil analysis shows extensive bivalve and ostracod fossils layered in organic matter. Phosphate and bone fragments can also be seen in thin sections. The fossil assemblage for this location within the Joggins Fm suggests a paleoenvironment with moderate marine influence, likely a brackish or estuarine environment. Lastly, this work contributes to our complete understanding of both the terrestrial and marine environments of this important site and the animals that lived within it

Royal Fish, Sea Monsters, and the Great Leviathan: Whales in Seventeenth Century England

The relationship between humans and whales has been transforming for centuries. This thesis aims to uncover the multi-faceted way in which whales were perceived in seventeenth-century England. The early modern English had varying and sometimes conflicting views of whales, considering them “royal fish,” useful commodities, and preternatural beings. This thesis analyzes the role whales played in legal disputes – particularly in the Crown’s claim to the foreshore, – investigates mariners’ shifting attitudes towards whales during the development of early English whaling, and explores the differing reactions of people ashore to stranded whales. What it reveals is that the tie between humans and whales has always been far more complex and dynamic than a simple predator-prey interaction. This thesis seeks to reinsert whales into our understanding of early modern England, while providing a lens through which we can reevaluate our past and current relationship with these “wonderous” marine mammals

EFFECTS OF ENHANCED EFFICIENCY NITROGEN FERTILIZERS ON THE AGRONOMIC AND ENVIRONMENTAL PERFORMANCE OF GRAIN CORN

Proper nutrient management is crucial for high yields, economic viability and environmental sustainability in agriculture. Nitrogen fertilizers enhance grain corn yields, but excess application can lead to N loss. Enhanced efficiency nitrogen fertilizers (EENFs) could mitigate this loss, but their effects on grain yields, quality, and the environment in Maritime Canada is under-researched. This study investigated the effects of EENFs on the agronomic and environmental performance of grain corn at three sites in the Canadian Maritimes, through four main comparisons: urea vs. EENFs, reduced vs. standard application rate, split vs. single applications, and EENFs applied alone vs. mixed with urea. Urea acted as a control, while three EENFs (PurYield™, SuperU®, and EENF_X) were evaluated. Results suggest PurYield™ and SuperU® can replace urea at a standard application rate without yield penalty, while EENF_X may cause a marginal yield reduction. PurYield™ reduced N2O emissions marginally compared to urea, but EENF_X exacerbated post-harvest soil NO3- N concentrations compared to all other fertilizers. PurYield™ maintained yields at a reduced rate of 100 kg N ha-1 while SuperU® reduced Truro-2023 yields at this rate. An application rate of 75 kg N ha-1 presented marginal yield reductions for both PurYield™ and SuperU®. Various application rates of EENF_X show no significant effect on yields. PurYield™ and SuperU® reduced N2O emissions at a rate of 100 kg N ha-1 compared to standard rates at Truro-2023 and Truro-2024 respectively. SuperU® showed marginally lower yields for a single application at Truro-2023, but otherwise, there were no yield, protein, or environmental differences between single and split applications. Mixing EENFs with urea showed no yield differences compared to applying EENFs or urea alone, but urea had higher N2O emissions than all treatments containing EENFs at Truro-2024, and higher NO3- N concentrations than certain EENFs in some cases, although results were inconsistent. Upon performing a return on investment analysis, 125U2T (125 kg N ha-1 urea split applied at planting and V6-V8), 100PY2T (split application of 100 kg N ha-1 PurYield™), 125USU2T (split application of 125 kg N ha-1 mixture of SuperU® and urea), and 125UPY2T (split application of 125 kg N ha-1 mixture of PurYield™ and urea) were consistently in the top five highest, suggesting these may be the most economical choices for producers. These findings provide farmers with recommendations on fertilizer products and management techniques to reduce environmental impact while maintaining grain yield, quality, and profitability, thereby enhancing agricultural sustainability

MAST CELL STING ACTIVATION IN INFECTION AND CANCER IMMUNITY

Mast cells (MCs) are long-lived, tissue-resident immune cells essential for host defense. The STING pathway, a key innate immune response to infection and cellular stress, promotes strong type I interferon (IFN) and pro-inflammatory responses. While the STING pathway holds therapeutic potential in cancer and infection, its role in MCs remains underexplored. Our study demonstrates that MCs trigger type I IFN and NF-κB responses upon STING activation. We show that MCs are susceptible to Shigella flexneri infection, leading to an upregulation of type I IFN and interferon-stimulated gene expression, partially dependent on STING. In a murine ovarian cancer model, MC deficiency led to longer survival, whereas reconstituted MC-deficient mice surprisingly showed improved survival. Treatment with a STING agonist increased survival, but overexpressing STING in MCs within tumors provided no additional benefit. These findings offer valuable insights into STING-mediated immunity in MCs and highlight potential avenues for future therapeutic exploration

Effects of Irrigation and Heat on Skin Blemishes in Dark Red Norland Potatoes

Dark Red Norland is an important potato cultivar in the fresh market in North America mainly due to its attractive red coloured skin type. However, three typical skin blemishes, including surface cracking, silver patch, and russeting, can negatively influence the tuber skin quality and marketability of this cultivar. A three-year field trial was conducted in this project from 2019 to 2021 to study the causes of these skin blemishes. Results showed that irrigation played an important role in Dark Red Norland’s total yield and reduced surface cracking. Tubers grown without irrigation formed more suberized cell layers. Heat stress affected the incidence of silver patch by reducing the total anthocyanin content in tuber skins. More silver patch was found on the downside of the tubers lying in soil. The outcome of this study provides key information and potential strategies to improve tuber skin quality and minimize market loss

ENDOLYSOSOMAL TRPML3 / BK COMPLEX IN AUTOPHAGY INDUCTION AND PATHOGEN DEFENSE

We found the TRPML3/BK feedback loop is important for efficient autophagy induction during nutrient deprivation or bacterial infection.The transient receptor potential mucolipin 3 (TRPML3), encoded by the MCOLN3 gene, functions as a calcium (Ca²⁺) release channel localized to endolysosomal membranes. This channel is activated by phosphatidylinositol 3,5-bisphosphate (PI3,5P2), with its activity further enhanced by elevated luminal pH or substitution of luminal sodium (Na⁺) with potassium (K⁺). In this study, we identify a positive feedback loop between TRPML3 and the big-conductance Ca²⁺-activated potassium channel (BK). Ca²⁺ release through TRPML3 activates BK channels, which subsequently enhance TRPML3-mediated Ca²⁺ release, likely by providing a counter flux of K⁺ and alleviating the inhibitory effect of luminal Na⁺. We further demonstrate that TRPML3/BK and the mammalian target of rapamycin (mTOR) form another positive feedback loop. mTOR inhibition during nutrient starvation activates TRPML3/BK channels, which further suppress mTOR activity, thereby increasing autophagy induction. Mechanistically, this regulatory interplay is mediated by phosphatidylinositol 3-phosphate (PI3P), an endogenous TRPML3 activator that is enriched in phagophores and becomes upregulated as mTOR activity decreases. Importantly, bacterial infection triggers TRPML3 activation in a BK-dependent manner, with both TRPML3 and BK playing crucial roles in the suppression of mTOR and the promotion of autophagy in response to infection. Inhibition of TRPML3 or BK enhances intracellular bacterial survival, while upregulation of either protein facilitates bacterial clearance. Given that TRPML3/BK is inhibited at low luminal pH but activated by high luminal pH and PI3P in phagophores, we suggest that the TRPML3/BK and mTOR feedback loop via PI3P is critical for efficient autophagy induction during nutrient deprivation or bacterial infection. These findings reveal a pivotal role for TRPML3-BK coupling in maintaining cellular homeostasis and mediating intracellular bacterial clearance by regulating mTOR signaling pathways