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The contribution of fish movement to ecosystem function in Lake Superior
Get PDFEcosystems are complex, highly interconnected systems in which organisms interact with their physical environment. Often, to simplify our understanding of their function, populations within ecosystems are treated as either spatially ubiquitous or discrete and fail to fully consider the costs and benefits of organism movement within and across ecosystems. This is especially prevalent in considering the ecosystem function of large aquatic systems like Lake Superior. Though most fishes in Lake Superior are known to exhibit large scale movements to spawn in the fall or spring, the costs and benefits resulting from this interconnectedness and daily behaviours of fish undergoing these movements are poorly characterized. This knowledge gap is due, in part, to limitations of current survey and assessment methods (i.e., mobile down-looking sonar surveys), which are costly, have known biases that underestimate fish populations, and are inadequate for detecting fine scale fish movements. To combat these gaps, I first used a new stationary acoustic platform to improve the accuracy of fish density estimates in the upper water column compared to traditional down-looking surveys and provide insight into ship avoidance behaviours and temporal migration patterns. I then applied this technology to describe inter-annual, regional, and diel differences in fish behaviour across Lake Superior. Finally, I examined the productive Lake Superior Shoals lakemount and found strong evidence of a deep chlorophyll maxima and of diel-vertical migration behaviour in the fish and Mysis at the shoals, both of which are key components for evaluating current-dependent hypotheses for elevated shoal production. However, I conclude that this shoal system would benefit from the use of the stationary acoustic platform as the current standard sampling methods were unable to provide substantial direct support for these hypotheses. [...
PGE–Cu–Ni sulfide mineralization of the mesoproterozoic Escape intrusion, northwestern Ontario
Get PDFThe Escape intrusion is a tabular to bladed, mafic–ultramafic chonolith that hosts
economic concentrations of PGE–Cu–Ni magmatic sulfide mineralization. The Mesoproterozoic
intrusion is located about 50 km northeast of Thunder Bay, Ontario, and with the Current
intrusion makes up the Thunder Bay North Intrusive Complex (TBNIC). The intrusive rocks of
the TBNIC are part of the 1.1 Ga Midcontinent Rift System (MRS) of North America and were
emplaced into the Quetico Basins during early stages of rift development. The fractionated HREE
(Gd/Ybcn = 3.18–4.96) signature of the Escape rocks suggests magma derivation from a deep
mantle source. Primitive mantle-normalized trace element patterns of the Escape intrusive rocks
are similar to ocean-island basalt, as well as multiple MRS-related mafic–ultramafic intrusions
(e.g., Hele, Disraeli, Kitto), which is consistent with the mantle-plume hypothesis of MRS
formation.
The high-grade zone occurs within the (mostly wehrlitic) peridotite unit of the Escape
intrusion, which lies below the weakly mineralized gabbro and hybrid units. The high-grade zone
within the Escape intrusion is characterized by intercumulus sulfide mineralization that is nettextured at the core and disseminated at the margins. [...
Toward foodsheds: reimagining food systems in the Lake Superior watershed
Get PDFThe Lake Superior watershed is nested within multiple Indigenous territories, two
settler-colonial nation-states, and a globalized capitalist economic system. While water
flows freely, the pursuit of social and ecological transformation is constrained by the
physical and psychological enforcement of human-constructed boundaries. Despite these
realities, watersheds are sites of great potential. Grounded in specific places while water
flows through to others, watersheds enable multiple streams toward justice and entry points
into food systems transformations. Foodsheds, named after watersheds, are overlapping
webs of food relationships. They offer alternatives to the place-less and relation-less
imaginaries of industrial food systems by grounding food communities in the places and
relationships they nourish. [...
Tracking stand-level responses (mortality and recovery) in jack pine (Pinus banksiana Lamb.)- dominated stands following the recent jack pine budworm (Choristoneura pinus pinus F.) infestation across northwestern Ontario
Get PDFThis study investigates the stand-level responses (mortality and recovery) in jack pine-dominated forests
following a recent infestation of the jack pine budworm across northwestern Ontario. The aim is to
understand the extent and severity of the infestation's impact on these forests and to identify potential
factors influencing the response of the stands. The research utilizes field data collected from 2019 to
2022, including tree mortality surveys and forest inventory assessments. The results show that the
budworm infestation has caused changes in natural mortality in the stands. The results have shown a
significant difference in crown density, whereas live tree density shows insignificant differences from
2020 to 2022. The overall diameter distribution between the JPBW stands and control stands showed that
the control site had a higher diameter and volume over all and continued to grow over time whereas the
JPBW stands maintained a similar distribution over time. Factors such as stand density, site quality, and
diameter distributions are found to influence the stands' response to the infestation. The findings and
literature indicate that a commercial thin of the affected stands could prove to be beneficial in preserving
stands as a whole and creating short term profit
A review of forestry’s impacts on methylmercury in aquatic ecosystems and recommendations for best management practices in Ontario’s boreal forest
Get PDFMercury contamination in freshwater fish of Northern Ontario is exceeding
levels safe for consumption and is negatively impacting remote communities. This
literature review examines the impacts of specific forest operations on mercury
contamination to aquatic communities. Literature was reviewed from online sources
using peer reviewed journal articles that contained relevant information to mercury
cycling or impacts of forest operations. The studies found that forest harvesting and site
preparation were responsible for increasing soil concentrations of methylmercury
(MeHg) between 100-500%. There were not subsequent changes in aquatic mercury
concentrations if hydrological connections between soils and water were minimized.
Fire reduced overall mercury concentrations in the soil and lessened the impact of site
disturbance on aquatic mercury concentrations. Current management practices in
Ontario are insufficient at preventing significant mercury contamination to freshwater
ecosystems. Incorporating more modern technology and harvesting practices, and
management strategies that minimize movement of mercury from forest soils to waters
should be the focus of future management directions
Female care partners’ experiences of their relative's transition to nursing home: a critical feminist perspective
Get PDFThe decision to transition a relative to a nursing home is usually preceded by many months or
years of physical and emotional care. While women continue to do most of the care work
throughout their lives due to socially and culturally constructed gender roles, little research has
explored female caregivers’ experiences in the transition of a relative to a nursing home
particularly through a critical feminist lens. The purpose of the study was to explore care
partners’ perceptions of this transition through a gendered lens, including changes in
relationships with relatives and care workers. Semi-structured interviews were conducted with
seven female care partners of nursing home residents. Data were analyzed using the voicecentred relational method. Three main themes emerged: 1) Care as women’s work; 2) Relational
care; and 3) Nursing home care. The study provided insight into the situatedness of women who
transitioned a relative to a nursing home. Care was taken on willingly, with emotional
commitment and a sense of duty which society constructed for them. Care was always embedded
in relationships, before and after the transition, impacting the care partners and relatives’ quality
of life. The Covid—19 pandemic affected their experiences significantly. Future considerations
of nursing home care improvements should include relational aspects of care, an understanding
of the situatedness of women as care partners and of women as care workers. Further research is
needed exploring the impact on relational care among care partners, residents, and care workers
due to the Covid-19 nursing home restriction
Valorization of Kraft lignin via alkaline and acid- mediated aerobic oxidation processes
Get PDFLignin is a complex heterogeneous aromatic compound derived from renewable plant biomass.
Due to its aromatic backbone, it has grown interested in producing biochemicals and other
polymeric applications. Depending on the sources and isolation methods, lignin has a wide range
of functional groups, such as aliphatic/aromatic hydroxyl, carboxylic, sulphonic, and methoxyl
groups, which make lignin chemically reactive for modification towards versatile applications.
The main goals of this dissertation are categorized into two main sections. Firstly, KOH
mediated aerobic oxidation of kraft lignin (KL) was performed to produce water-soluble KL that
was applied as green fertilizer on maize seedlings and a mid-range cement plasticizer. Secondly,
oxalic acid mediated oxidation of KL was conducted to produce aromatic biochemicals such as
vanillin and vanillic acid.
In this dissertation, the KL was aerobically oxidized in KOH solution to produce water-soluble
anionic lignin. The oxidation reaction was optimized to achieve the maximum carboxylic acid
groups and charge density. The XPS, 1 H-NMR, and 31 P-NMR confirmed the introduction of the
carboxylic acid groups, while the FTIR, and HSQC-NMR confirmed the structural alterations in
the oxidized lignin. The extensive degradations of the aromatic moieties (G-units) of lignin
confirmed its ring openings during the alkaline oxidation. The fertilizing effects of the modified
lignin were investigated on Zea mays seedlings. [...
Floristic composition and functional stability of black spruce-Kalmia shrub savannah
Get PDFScope: In eastern Canada, black spruce (Picea mariana)-Kalmia angustifolia forest revert
into forest, or become Kalmia heath, or Kalmia-spruce shrub savannah (SS) depending on
fire severity. My main research objective was to identify the mechanisms that maintain
SS vegetation structure and function. I hypothesized that microhabitat conditions and
function of dominant plants of island and heath confer SS stability.
Methodology: I used a multivariate approach to quantify the difference in habitat
condition, floristic structure and composition between island and heath of SS. I compared
soil nutrient availability and litter decomposition between island and heath to assess
growth limitations and nutrient cycling. This was followed by determining functional
hypervolumes of the four most abundant species in island and heath considering four
functional traits representing resource acquisition and use. I used a dendrochronological
approach to determine island expansion rate to predict future island cover.
Results: Shrub cover, light availability, and soil moisture were positively related to heath,
and cryptogamic species and tree cover and organic matter depth were positively related
to island. Heath soil had higher total N, but lower total C, and K than island. All other
measured nutrients were similar. Black spruce litter decomposed faster than Kalmia. [...
A framework to avoid maloperation of transformer differential protection under geomagnetic disturbances
Get PDFGeomagnetically Induced Currents (GICs), which are generated due to Geomagnetic
Disturbances (GMDs), can saturate the cores of power transformers and their associated
Current Transformers (CTs). To avoid maloperation of Transformer Differential relays
in the presence of GICs, this family of relays is often equipped with Harmonic Blocking
(HB) or Harmonic Restrain (HR) functions. These two functions, however, negatively
impact the sensitivity and dependability of differential relays during GICs. Thus, if an
internal fault occurs in the presence of GICs, it might remain uninterrupted. On this
basis, this study proposes an auxiliary framework for single-phase transformers or threephase transformer banks to address the above-mentioned issues for differential relays and
their CTs without sacrificing the sensitivity and/or speed of differential protection. This
framework benefits from the Linear Parameter Varying (LPV) state-space equations
of CTs and power transformers, and convert them to their polytopic form. Then, it
employs LPV observers to estimate the states of the transformer and its CTs. To
counter CT saturation, the framework precisely calculates the primary currents of CTs
based on their secondary currents, allowing the differential scheme to use the estimated
primary currents rather than distorted secondary currents. Furthermore, the proposed
framework detects internal faults by comparing the estimated primary current of the
transformer with the measured one. The difference between the estimated and measured
currents is almost zero when no internal fault is present during GMDs; however, the
discrepancy between the two grows as soon as an internal fault occurs. The effectiveness
of the proposed framework is validated through simulations in Electromagnetic Transient
Program (EMTP
The association of rat prevalence and composting in Thunder Bay’s urban neighbourhoods
Get PDFLandfilling is the most common municipal solid and urban organic waste
disposal method in North America and comes with numerous negative environmental
side effects. Encouraging greater participation in community composting could help to
minimize or mitigate these effects while also improving social and economic
conditions within communities. However, there is still relatively low participation in
the practice and apprehension of urban pests may be a significant contributing factor.
In Thunder Bay, ON, the Norway rat (Rattus norvegicus) is a common pest that
may be contributing to the community’s hesitancy to embrace household composting
as an alternative waste management strategy. To determine if composting is associated
with rat presence and if apprehension of rats is a significant deterrent to household
composting within the city, residents of Thunder Bay’s urban neighbourhoods were
asked to participate in a survey examining their waste disposal habits and subsequent
experience with rats.
The survey found that there was no relationship between composting frequency
and rat abundance. A significant number of non-composting residents associated their
decision not to compost with the fear of attracting rats to their property. Despite these
fears, participants that were not composting more frequently experienced rats on or
around their property than those who were composting. Other contributing factors to
the relatively low numbers of urbanites composting were a lack of education on how to
compost properly and a lack of accessibility to composting services for those with too
little time or little desire to compost out of their own homes