Theses (Geography)

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    Characterizing Phytoplankton Community Composition in the Open and Coastal Waters of the Subarctic Northeast Pacific Using In situ and Remote Sensing Techniques
    (2024) Perumthuruthil Suseelan, Vishnu; Costa, Maycira
    Phytoplankton are the foundation of the marine food web and play a central role in global biogeochemical cycles. The overarching phytoplankton community contains a diverse array of species with distinct ecological and biogeochemical traits and niches. As a result, variations in the composition of phytoplankton communities can significantly affect energy transfer through the marine food web, fisheries production, and the vertical export of carbon into the deep ocean. In the subarctic northeast Pacific (SNEP), phytoplankton plays a distinct role in sustaining fisheries through match-mismatch dynamics. Previous studies in this region have mainly relied on in situ measurements, such as HPLC pigment data, Chemical taxonomy software (CHEMTAX), light microscopy, and physical-biological models, to study phytoplankton communities, but lacking the utilization of satellites. This study employs a comprehensive approach, integrating in situ observations, Earth Observation satellite data, and above-water radiometry, to thoroughly examine the composition of phytoplankton communities. To achieve this goal, first we provide evaluation of the Ocean Land Color Instrument (OLCI)-derived products for Case-1 waters, specifically total chlorophyll-a concentration (TChla; mg/m³) and remote sensing reflectance (Rrs; sr⁻¹), obtained from the POLYMER (POLYnomial-based algorithm applied to MERIS) and the European Space Agency’s (ESA) Baseline Atmospheric Correction (BAC) algorithms. Here, we determined that POLYMER performed better than the BAC algorithm across all bands, with the latter resulting in a loss of approximately 60% of valid data points due to the inability to retrieve products under winter cloud conditions. Additionally, POLYMER successfully captured the regional dynamic range of TChla and aligns well with in situ HPLC TChla data. Next, the study characterizes the composition of phytoplankton communities in Case-1, iron-poor open ocean waters and highly dynamic Case-2 coastal waters in the northeast Pacific using data from the Sentinel 3 OLCI satellite. Utilizing an empirical orthogonal function (EOF) approach, a Sentinel 3 OLCI-based algorithm trained with a regional matchup dataset consisting of phytoplankton groups Chlorophyll-a (Chla) and EOF scores derived from Rrs is employed. Additionally, the robustness of the algorithm is statistically assessed through cross-validation. The Sentinel 3 retrievals from 2019 indicate low biomass for all groups in open ocean Case-1 waters, with minimal variability observed across multiple composites. However, increased biomass is observed for all groups except Hapto/Pelago/Cyano towards the northern Gulf of Alaska (GoA), which aligns with CHEMTAX analysis. Conversely, the 2020 composites reveal a longitudinal gradient from the open ocean to the continental shelf/coast for Diatoms/Dino/Green Algae, but an inverse trend is observed for the Hapto/Pelago/Cyano group. Redundancy analysis (RDA) demonstrates that open ocean flagellate groups are positively correlated with Mixed Layer Depth (MLD) and sea surface salinity (SSS), while Diatoms/Dino/GA are negatively correlated with MLD and SSS. In contrast, satellite-based retrievals for the Case-2 water of the west coast of Canada illustrate seasonal spring and fall blooms dominated by diatoms in the Strait of Georgia (SoG), with the highest biomass concentrated in the central, northern, and Juan de Fuca Strait. During the summer, a similar diatom-dominated trend is observed, with the highest biomass recorded on the southwestern coast of Vancouver Island. Interestingly, raphidophytes exhibit the highest average biomass during the summer, with blooms observed off the southwest coast of Vancouver Island and near the Fraser River mouth. The study further explores the spatial-temporal dynamics of phytoplankton composition within the SoG using EOF retrievals from high-resolution hyperspectral Rrs obtained from autonomous platforms. The results indicate better retrievals for all groups than those obtained using Sentinel 3 OLCI data. Overall, the algorithm successfully predicts the localized, diatom-dominated spring bloom and reveals high variability in flagellate communities, with the highest average biomass occurring in the summer. Furthermore, our algorithm captured strong raphidophyte blooms composed of the harmful algae species, Heterosigma akashiwo. Additionally, our high-resolution transect data derived from the algorithm highlighted peaks in raphidophyte and diatom coinciding with a sharp decline in SSS suggesting a frontal region within the Fraser River plume. In summary, using data from in situ measurements, satellites, and autonomous platforms, along with supporting environmental driver data, provides a more comprehensive understanding of the dynamics of individual phytoplankton groups, including harmful algal bloom dynamics with significant implications for water quality monitoring and fisheries management in this region.
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    Drivers of Coastal Morphodynamics on a Deltaic Barrier in the Colombian Caribbean
    (2024) Gómez, Juan Felipe; Kwoll, Eva; Walker, Ian J.
    This research presents results from a series of analyses focussed on the overarching goal of identifying and understanding drivers of coastal morphodynamics on a deltaic barrier in the Colombian Caribbean coast, eastward from the Magdalena River mouth. Forcing mechanisms operating at different temporal scales were considered, including the influence of vertical land motion (VLM), storms, river discharge, trade winds, and wave conditions. These forcing mechanisms were related to geomorphic changes determined from satellite imagery taken before and after specific events. Satellite imagery and synthetic aperture radar acquisitions were used to assess decadal-scale coastline changes and VLM for the period 2007–2021. The findings revealed that VLM rates are highly variable alongshore, and that subsidence occurs mainly landward of highly erosive stretches of coastline associated with former mangrove forest. Drivers of coastal morphodynamics operating on time spans from days to seasons were assessed by focusing on four lagoons located along the back-barrier to better understand the interplay between extreme events and the breaching and healing of inlets that are temporarily formed between the lagoons and the ocean. Satellite data in conjunction with hourly readings from weather stations spanning the past 50 years helped to determine the conditions that enabled the breaching and healing processes to transpire in the lagoons. Aligned with the predominantly erosive regime along the study area, the findings indicated that the cumulative effect of the breaching and healing of the lagoons resulted in a deltaic barrier that has rolled over the lagoons, modifying their size over time. The occurrence of meteotsunamis and their role in coastal morphodynamics was investigated using a wavelet analysis applied to water-level readings in three tide gauges for the period 2013–2022. After the discovery of one event with meteotsunami-like characteristics, the atmospheric conditions and total water levels associated with this event were analyzed. The results indicated that total water levels related to the meteotsunami are similar to those produced by moderate storms and both phenomena can induce breaching of lagoons. To date, the barrier has responded to external forcers through a landward displacement of the coastline driven by cycles of lagoon breaching and healing as well as overwashes on lagoons, wetlands, and beaches. Seasonal storms have been critical in forcing these processes and have substantially influenced the barrier evolution during the last 50 years. Taken as a whole, this body of work provides knowledge about the response of deltaic barriers to geomorphologic forcers based on a study area in an understudied region of the Caribbean. At a regional level, the findings are relevant for science-based coastal planning and managing policies. Moreover, this research used a variety of methodological approaches to track causality on coastal landscapes in a manner that can be replicated in other areas with limited pre-existing information and without ongoing monitoring programs.
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    Assessment of Arctic sea ice properties during advanced melt using C- and L-band polarimetric synthetic aperture radar
    (2024-01-03) Tavri, Aikaterini
    Over recent decades, there have been significant changes in Arctic sea ice, marked by a shift from thicker to thinner ice, and reductions in extent and volume. These changes, along with extended melt seasons, have accelerated sea ice melt and the ice-albedo feedback. This dissertation leverages Synthetic Aperture Radar (SAR) to analyze sea ice dynamics and thermodynamics at various scales. Focusing on the advanced melt season, this dissertation examines the relationships between sea ice geophysical properties and SAR backscatter signatures at C- and L-bands. Our analysis uses RADARSAT-2 (C-band) and ALOS-2/PALSAR-2 (L-band) imagery in different polarimetric modes to assess sea ice type separability and the effects of incidence angle and melt ponds on backscatter. We discover that C-band SAR is more effective early in the melt season, while L-band SAR provides clearer delineation of ice features later in the season. Additionally, the co-pol ratio (VV/HH) was found to be a consistent indicator of the melt ponds for FYI, despite environmental changes, such as wind-roughened melt ponds, for both frequencies and incidence angles in the near and far range. Utilizing our findings, we developed a dual frequency, dual-incidence angle sea ice classification approach using a random forest classifier. We achieved over 70% accuracy in sea ice type classification, validated by airborne measurements. This research underscores the value of a dual-frequency approach in improving sea ice classification, particularly for first-year and multi-year ice during advanced melt stages, while considering the evolution of deformed ice types in the advanced melt season. The findings contribute significantly to climate studies and operational services and are pertinent to future dual-frequency SAR missions.
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    Assessing the ability to detect and identify forage fish schools and species from Remotely Piloted Aircraft Systems video surveys in Coastal BC
    (2023-10-26) Houtman, Nicola; Costa, Maycira; Robinson, Clifford L. K.
    Remotely piloted aircraft systems (RPAS) present a potentially efficient method for quantifying surface-schooling forage fish species in important nearshore habitats. In British Columbia, this method could help fill data gaps in the distribution and abundance of key forage fish species (e.g. Pacific herring, Northern anchovy, Pacific sand lance). However, the ability to detect subsurface targets in marine habitats in aerial imagery is subject to errors caused by poor environmental conditions (e.g. high turbidity, waves, sun glint) and influenced by target characteristics (e.g. depth in the water column, contrast with background, size). Here, we aimed to evaluate the effects of environmental and target variables on fish detection in RPAS imagery through a controlled experiment (Objective 1) and tested this method at natural conditions in nearshore sites around Vancouver Island, BC (Objective 2) to create a method that can be used to quantify forage fish with maximum accuracy for future conservation purposes. In objective 1, by collecting imagery of a model fish school placed at different depths under a wide range of environmental conditions, we determined that RPAS surveys should target clear skies, low to moderate sun altitudes, glassy seas, low winds, and low turbidity. Target colour and depth also impacted the ability to detect the forage fish-like lures. In objective 2, we detected 612 forage fish schools in 750 minutes of RPAS video imagery collected around coastal Vancouver Island. We were able to identify shiner surfperch with high confidence but were not able to differentiate sand lance and herring very often. Additionally, we found that among school fish characteristics and environmental conditions, school size and contrast, and wave height and sun altitude greatly impacted the detectability of forage fish schools in RPAS imagery. These results will help inform future RPAS forage fish surveys and minimize detectability errors.
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    Conflict in Complex Social-Ecological Systems: Understanding conservation conflicts in Canada towards their transformation
    (2023-09-26) Eckert, Lauren E.; Darimont, Chris
    In the 21st century, human pressure on Earth has resulted in widespread ecosystem degradation and biodiversity loss, and proposed solutions often spark conflict. These resulting conservation conflicts take many forms, occurring across geographical scales and locations, and within and between stakeholder groups, communities, nations, and species. These multifaceted conflicts are often considered among the most intractable problems in modern conservation sciences. Scholarly frameworks and practical methods are urgently needed to support our understanding of these conflicts, and our ability to pursue human- and environmental-well being. In this dissertation, I examine three conservation conflicts, two among people, and one between wildlife and people, which vary in scale and other system characteristics. My dissertation answers three core questions: i) How can a CCT approach inform assessment of Canadian environmental-decision making processes as they attempt to embrace multiple forms of knowledge and many interested parties?, ii) What existing bodies of scholarship and social science-derived methodologies and models might be mobilized within a CCT framework? Might some of these other models and supporting scholarship contribute repeatable methodologies to the CCT literature?), and iii) How can a CCT approach inform studies of human-wildlife conflict? Can CCT processes be aligned with ecological research assessing human-wildlife conflict to examine these conflicts more holistically? In the process of answering these questions, I develop new methods, frameworks, and data towards better understanding these and other conflicts and supporting their transformation. In Chapter 2 (published in FACETS, 2020), my coauthors and I assess conflict between knowledge types in environmental decision-making processes. In the last 50 years, many western societies have used environmental assessment (EA) processes to deliberate on industrial proposals, informed by scientific information, though results of these processes often spur conflict. Recently, some EA processes have attempted to incorporate Indigenous knowledge (IK), but practitioners and scholars have criticized the ability of EA to meaningfully engage IK. We considered these tensions in Canada, a country with economic focus on resource extraction and unresolved government-to-government relationships with Indigenous Nations. In 2019, the Canadian government passed the Impact Assessment Act; addressing this opportunity, we examined obstacles between IK and EA via a systematic literature review and qualitative analysis. Our results identify obstacles preventing the Act from meaningfully engaging IK, some of which are surmountable (e.g., failures to engage best practices, financial limitations), whereas others are deep-rooted (e.g., knowledge incompatibilities, effects of colonization). We offer recommendations towards transforming conflicts between IK and EA towards improved decision-making and recognition of Indigenous rights. In Chapter 3 (submitted to Conservation Science and Practice), my coauthors and I examine stakeholder conflict over how best to manage marine species of shared concern. A first step in overcoming conflicts is examining their roots in people’s identities and beliefs - rather than focusing solely on the visible conflicts at hand. In the Salish Sea region of British Columbia (BC), Canada, conflict has emerged surrounding Southern Resident Killer Whales (SRKW) (Orcinus orca) and Chinook salmon (Oncorhynchus tshawytscha). SRKW are critically endangered due to intersecting stressors – among them depletion of Chinook. The Department of Fisheries and Oceans Canada has passed measures that restrict recreational fishing of Chinook to protect SRKW. Public response to protection measures has been conflict-laden and is especially tense between so-called angler and conservation-oriented communities – two stakeholder groups assumed to be distinct and at opposite sides of conflict. Employing social science methods, we used online surveys to examine the social identity, environmental identity, beliefs, and opinions of those involved in this conflict. Most survey participants (n = 816) self-identified as either conservation-supporters (49%) or anglers (33%). Our analyses revealed demographic differences, with anglers generally overrepresented by men, those with higher incomes, and those with 2-year terminal degrees. Both groups scored similarly high in environmental identity and stakeholder identify affiliation scores, also showing positive correlations between the intensity of identities with participation in public discourse. Stakeholder groups differed strongly in management opinions and beliefs. Ultimately, our results identify conflicts between Salish Sea stakeholder groups as deeply-embedded. Commonalities (especially in beliefs regarding Chinook salmon), however, identify a path forward that draws on conflict transformation theory. Our approach offers new generalizable insight into the levels-of-conflict framework within conservation conflict transformation theory to inform scholarly and practical endeavours. In Chapter 4, my coauthors and I assess the social-ecological drivers of human-wildlife conflict. Conflict between humans and wildlife presents significant threats to human and wildlife well-being. Research that comprehensively examines the ecological and social dimensions of human-wildlife relationships can provide new insight into management interventions that promote coexistence. In BC, human-wildlife conflicts have increased substantially in the last two decades, with most occurring between humans and black bears (Ursus americanus). Despite mitigation attempts, conflict in the Qathet Regional District is pervasive. How social and ecological factors concurrently predict conflict is poorly understood in the region and the scientific literature. We examined the spatially-relevant ecological (e.g., bear relative use, land cover) and social (e.g., beliefs, behavior) predictors of conflict to understand how they might explain variation in its frequency and distribution. . Via a mixed methods approach, we used remote sensing, camera traps, property audits, and social surveys across 27 randomly selected 200-metre by 200-metre grids within the Qathet Regional District (n = 1,271 households). Social surveys revealed variation in participant beliefs about bears; most (52%) considered their overall experience with bears positive, while others reported neutral (32%) or negative (13%) overall experiences. Moreover, our generalized linear mixed-model and an information-theoretic approach identified which variables (or combination) predicted conflict outcomes. We found that road density, household garbage, and participant perception of risk increased the probability of conflict, whereas human density had a negative effect. An interaction term between household garbage and risk perception revealed a positive association between conflict and garbage only when risk perception was high. Relative variable importance determined that household garbage and risk perception were the most important predictors. The interplay between these social and ecological predictors and their resulting influence on conflict reveal new targets for intervention by local collaborating organizations via education, monitoring, and enforcement. More broadly, we showcase an interdisciplinary methodological framework that spans ecological and social approaches, offering promise to confront and mitigate enduring conflict between people and wildlife. By analyzing three disparate case studies of conflict across policy, environmental decision-making, intergroup conflict, and human-wildlife conflict contexts, I contribute to scholarly understanding of the anatomy and complexity of conservation conflicts. In this dissertation, I provide new insight, methodologies, and contributions to understand and, hopefully, transform conservation conflicts.
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    Working Together: The Role of Maasai Youth in Local Economies
    (2023-09-12) Herchak, Katelynne; Tremblay, Crystal; Carodenuto, Sophia
    This thesis examines the relationship between Maasai youth and their role in local economies in the community of Elerai in Tanzania. Through a community-based participatory research partnership, photovoice was used as a methodology to explore this primary inquiry, and also providing additional insights into the impacts of youth migration and the ongoing threats due to climate change on the community. Maasai youth acted as community co-researchers during several focus group discussions to explore research questions about the role of Maasai youth in local economies. In particular, my thesis investigates several sub-questions: How do Masaai youth feel about young people leaving the community? and What do Maasai youth perceive to be the future of their economies? This research is part of a broader community-based research partnership with several Maasai communities and took place during the summer of 2022. This work is intended to be a form of art and medicine for Maasai youth teaching and learning from each other.
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    Traders as Implementors of Sustainability in Tropical Agriculture Supply Chains
    (2023-09-11) Silverman, Sofia; Carodenuto, Sophia
    Tropical agriculture commodities such as cocoa, coffee, and palm oil are popular ingredients across the globe. Despite their abundance, these crops have geographically few growing regions and are often concentrated in countries in the Global South. In order for products to transform from their raw form to their final consumable form, the commodities undergo significant travel and transformation across supply chains. Along these supply chains, known environmental and socioeconomic challenges are embedded at all stages. Stakeholders along the supply chain have long tried to remedy barriers and seek sustainable practices with little scalable success. But recent studies have realized there needs to be increased research dedicated towards a relatively opaque actor, traders. Traders are actors at the center of supply chains and mainly facilitate the movement of crops from upstream producers to downstream consuming markets, but they also serve as communicators along supply chains. This central position provides traders significant insight vertically across supply chains and horizontally across different crop markets. Still, little is known about how traders use this advantageous position and specialized knowledge to advance sustainability and equity goals. This thesis investigates the identified research gap using the Delphi Method and engages with traders not only as the research target but also as research participants. Working alongside academic and trading practitioners, the overall aim of this thesis is to address barriers preventing traders from operationalizing sustainability and looks at traders' self-perceived roles, responsibilities, and opportunities in furthering sustainability objectives in tropical agriculture supply chains.
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    Biofouling growth risk assessment on Atlantic Salmon (Salmo salar) farm nets: exploring links to environmental factors
    (2023-09-07) Johnson, Devan; Flaherty, Mark S.; Pearce, Christopher Michael
    Recently, salmon aquaculture companies in British Columbia, Canada, have experienced significant fish losses resulting in tens to hundreds of millions of dollars in damages due to gill disorders and mouth lesions. Hydroids, the colonial stage of some cnidarians, are the most likely problematic species. Field studies were conducted to examine biofoulant composition, gill health, and the interactions between water parameters, biofoulants, and gill health. In 2020, biofouling was observed at two fish farm sites in the Broughton Archipelago from April 20 to October 30 by suspending 30x30 cm net patches at five depths (1, 5, 10, 15, and 20 m). Net patches remained in the water for 1-3 weeks between pen cleanings (via power washing). After collection, the biofoulants were identified and counted, with hydroids removed and weighed separately. In addition, tow samples were collected weekly to identify any free-swimming stinging-capable species. Biofoulant compositions were mainly composed of Mollusca (mostly Mytilus sp.) and Arthropods (mostly Harpacticoids), hydroids were mostly composed of Obelia sp., and tow samples were composed of mostly medusa-form Obelia sp. GLMMs were built to examine the relationships between the water parameters and the biofoulant species counts, hydroid biomass, and tow sample counts. Both sites saw nearly every parameter significantly associated with biofoulant counts, with the effects stronger at Wicklow Point. Similarly, nearly all parameters were associated with hydroid biomass, however the effects were stronger at Doctor Islets. Only two (ammonia and nitrate levels) and one (ammonia) parameters were associated with the counts of sting-capable species in the tow samples from Doctor Islets and Wicklow Point, respectively. CLMMs were built to examine the relationships between gill health, biofoulant counts and biomass, and water parameters. Iron, nitrate levels, and pH were significantly associated with gill health at Doctor Islets, and temperature, pH, and dissolved oxygen were significant at Wicklow Point. No biofoulant species counts or hydroid biomass from the net patches were associated with gill health, however, when the gill health scores were sampled after a net patch collection gill scores were significantly higher at both sites. At Doctor Islets, no stinging-capable species counts were associated with gill health and at Wicklow Point, counts of Sarsia sp., Bourgainvilla sp., Clytia gregaria, and Diphydae spp. were significantly associated with gill scores. Like the net patch samples, when gill scores were recorded after a tow collection, gill scores were significantly higher.
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    Perspectives on Indigenous knowledge governance in collaborative environmental stewardship
    (2023-08-24) Hodgson, Jean; Tremblay, Crystal; Bone, Christopher
    Growing from inherent rights to steward territories, the weaving of Indigenous knowledge into environmental stewardship is increasingly being acknowledged and mandated for, both in Canada and internationally. The deep settler colonial roots of environmental stewardship and resource management in Canada, as well as the violence enacted on communities within these spaces and through resource management practices, make this a contentious and deeply complicated task. Furthermore, engagement with Indigenous peoples and their knowledge systems has historically been, and continues to be, extractive, dismissive, and paternalistic, disrupting Indigenous ways of being and failing to recognize inherent rights. In tandem with environmental stewardship rights, Indigenous peoples have articulated and asserted their inherent right to govern their knowledge and data. Indigenous knowledges come from and are practiced on lands and waters and, as such, Indigenous knowledge governance and environmental stewardship are deeply interconnected. However, there are tensions between the recognition of and interest in weaving Indigenous knowledge into environmental stewardship, while adhering to Indigenous knowledge governance principles that ensure protection and prevent extraction, exploitation, or misuse. Growing from this tension, this study is situated in a collaborative Marine Spatial Planning (MSP) program on the South Coast of British Columbia where federal, provincial, and First Nations governments are partnering to envision and plan marine use in the region. Using community-based participatory research methodologies, this study was developed with First Nations partners at the First Nations Fisheries Council of British Columbia (FNFC) and asks how Indigenous knowledges may be ethically and equitably woven into the marine planning process. To do this, I hosted focus groups and interviews with individuals working for each of the MSP partners and sought to better understand perspectives on and experiences with knowledge governance in collaborative environmental stewardship work. The intention driving this study was to provide insight and potential recommendations that may support the FNFC and partners in establishing an MSP process that adhered to and was founded in Indigenous knowledge governance principles and practices. Project findings demonstrate that, rather than understanding knowledge as an object or evidence base separate from people and governance, knowledge systems must be recognized. Thus, expanding mainstream conceptualizations of knowledge governance to include support for and recognition of the systems and people that generate, practice, and hold knowledge. From this vantage, operational considerations include both technical approaches and tools, as well as transformational change required at a societal and individual level. This transformational change must be situated in decolonizing theory and grounded in everyday realities and practices.
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    From Diversity to Disruption: Revisiting the Keystone Species Concept
    (2023-08-22) Shukla, Ishana; Darimont, Chris T.
    The keystone species concept has been a staple of community ecology since its conception by Robert Paine in 1969. However, despite its prominence in community ecology, literature synthesizing the landscape of keystone diversity is lacking. Similarly, how keystones respond to an increasingly human-dominated world is also unknown. To address this, we created a database of keystone species identified by the literature and classified overarching patterns in keystone traits. We additionally measure the magnitude of community response associated with a keystone’s extirpation or decline via human disturbances. After compiling a list of 230 animal keystones, we identified 5 distinct archetypes via a k-means clustering analysis: high trophic level (or “high level”) vertebrate consumers, low-level vertebrate consumers, low level invertebrate consumers, low level invertebrate modifiers, and low-level vertebrate modifiers. We also found that communities respond to a keystone’s loss with a similar magnitude whether resulting from lethal or non-lethal-caused extirpation. Finally, we found the largest community responses were elicited from small, modifier keystones. These results challenge current cultural perception of keystones as exclusively large carnivores, and instead place an emphasis on smaller, less charismatic keystones. These results, along with our novel database, can aid policymakers and scientists alike in approaching keystone conservation from a more holistic perspective.
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    Carbon Sequestration of Eelgrass Meadows in Clayoquot Sound, BC: An Identification of the Environmental Drivers of Sediment Carbon Variability
    (2023-06-01) Prior, Jordan; Kwoll, Eva
    Carbon storage mechanisms have seen increased attention to remove atmospheric carbon with the capability of seagrass meadows to sequester and store carbon becoming a key research objective within the Pacific Northwest (PNW). This study attempts to identify the environmental drivers of sediment carbon variability with a differentiation between allochthonous and autochthonous carbon. Seven seagrass meadows within Clayoquot Sound, BC were selected as determined by seagrass and morphological characteristics (tidal velocity, grainsize, slope, depth etc.). Carbon stocks varied among sites with five sites ranging between 21.1 ± 1.4 gC m-2 and 28.9 ± 1.6 gC m-2. Two outliers were observed with 56.6 ± 2.8 gC m-2 and 15 ± 1.8 gC m-2 – resulting from a low D50 reflecting the propensity to sequester allochthonous carbon at the first site and a high velocity limiting deposition of allochthonous carbon at the other site. Average carbon stock (to 25 cm depth) throughout Clayoquot Sound for this study is 653.6 gC m-2with a range of 366.3 to 1421 gC m-2. Carbon accumulations aligns with previous studies with this study showing a range of 0.5 to 47 gC m-2 y-1. Analysis of isotopic signatures, conducted via a Bayesian mixing model, show a strong allochthonous signal primarily from marine sources with terrestrial sources seen nearer to river mouths. Through the use of multivariate linear regression analysis, high tidal velocity is seen to be related to high autochthonous carbon due to suspension of sediment. In contrast, velocity and grainsize are seen to be related to marine carbon and terrestrial carbon is related to grainsize. This understanding shows that seagrass characteristics and spatial extent are not the only important variable to estimate carbon stocks and that there are definitive linkages between tidal velocity, grainsize, morphology (depth and slope) and carbon stocks. The extrapolation of carbon stocks beyond Clayoquot Sound could be better accounted for by using meadows, tidal measures, local bathymetry and local sediment characteristics. However, these variables are currently under-used in the modelling of carbon stocks for the PNW and around the world.
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    Using Geovisualisation to Show the Outcomes of Invasive Species Management Strategies
    (2023-05-18) Willyono, Elvia; Bone, Christopher; Newell, Robert
    3D geovisualisations are potential tools that can facilitate spatial decision-making processes by providing realistic representations of the local environment. Geovisualisations allow decision-makers to explore scenarios and assess potential impacts of different management options. While there exists a broad range of geovisualisation applications, lacking from the literature is an evaluation of the degree to which geovisualisations can assist in the management of invasive species, particularly related to non-native plants. With the increase of globalisation and climate change, invasive plant species are becoming a growing threat to biodiversity and the management of parks and protected areas. The spread of invasive plants continues to rise through continued increased in globalised trade and travel, and climate change may provide additional pathways as changes to temperature and precipitation regimes provide hospitable conditions for non-native vegetation to establish and flourish. Thus, controlling invasive species is essential and a necessary step towards the long-term conservation of natural vegetation and fauna in parks and protected areas. The overall goal of this thesis is to evaluate the utility of geovisualisation for facilitating the management of invasive plants in protected areas. Specifically, this thesis aims to determine how geovisualisations can potentially bridge the gap between research-generated knowledge and applied implementation of invasive species management. This work is centred on a case study involving stakeholders involved with the management of a protected area, whereby individual perceptions of the utility of a geovisualisation for facilitating decision-making are assessed. The results of this study demonstrate that the geovisualisation tool can be an effective tool for enhancing understanding of the management of invasive species in parks and protected areas. The geovisualisation tool enabled stakeholders to better understand the spatial distribution and impacts of invasive species on Mitlenatch Island, thereby strengthening their sense of place. However, further research is needed to explore alternative approaches for visualising the effectiveness of invasive species management strategies.
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    An Assessment of Seasonal Source Water Contributions to Streamflow in the Athabasca River Basin, Utilizing a Novel Approach to Obtain a Record of Winter Streamflow From River Ice Stratigraphy
    (2023-01-09) Taulu, Jasmine; Atkinson, David
    The objective of this thesis is to quantify seasonal source water contributions to the Athabasca River in Alberta Canada. A secondary objective was to evaluate a novel method for reconstructing the isotopic composition of streamflow over the ice-on period and utilize this data to quantify source water contributions to winter streamflow. Quantifying source water contributions to streamflow is important because the Athabasca is a large, snow-dominated catchment where climate change is expected to impact the quantity and timing of source waters. The water resources in the Athabasca River Basin (ARB) are essential in supporting communities, the economy and ecosystems in the province of Alberta. This includes water needs of municipalities, oil sands operations and sensitive ecosystems, such as the Peace Athabasca Delta, an internationally recognized protected area. While the lower reaches of the Athabasca has been the subject of many studies, stable water isotope analysis has been limited in the upper portion of the ARB leaving a knowledge gap around existing snow and glacial melt water resources. This research focuses on the Upper and Middle reaches of the Athabasca and includes a subset of data for the McLeod catchment, which is nestled in the Middle Athabasca. To assess source water contributions three synoptic studies were undertaken to collect stable water isotope samples over a hydrological year from August 2016 to August 2017. This dataset was supplemented by winter streamflow data calculated using a novel method that reconstructs the isotopic composition of winter streamflow using river ice stratigraphy. The reconstruction of streamflow in the ARB produced accurate results as validated against streamflow sampling obtained over the same time period. This method also resulted ice-water fractionation values that were in alignment with the existing literature. While these results support the future use of this emerging methodology, additional studies will be required to better define the limitations to this methodology. Source water contributions to streamflow were calculated for all field samples and reconstructed values using hydrograph separation. This allowed the relative contributions of snowmelt, glacial melt, groundwater and evaporatively enriched surface waters, such as from lakes and wetlands, to be quantified. The results from this analysis have established a spatially explicit, baseline understanding of the major contributions of seasonal and annual source waters in the region. Observed patterns included an accumulation of surface water downstream in the ARB and annual source water cycling in the McLeod catchment, that aligned with results found in other studies in the Mackenzie River Basin. Trends differed in 2016 and 2017 but were linked to differences in temperature and precipitation over the two years. While this research has established baseline source water information across the Upper and Middle Athabasca, future studies to conduct a higher temporal and spatial resolution sampling of streamflow and source waters across the catchment are recommended.
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    Assessing RADARSAT Constellation Mission sea ice surface topography retrievals using data from ICESat-2
    (2023-01-06) Rezania, Parnian; Scharien, Randall
    Recent sea ice dynamics research and ice forecasts focus on the importance of sea ice topography and thickness. Sea ice topography is a critical component in sea ice drag forces, understanding sea ice motion and extent, heat transfer at the ocean-atmosphere interface, and safe ice-related decisions in marine navigation. The overarching objective of this study is to assess the inter-relationships of optical laser altimeter Ice, Cloud, and Land Elevation Satellite-2 (IS-2, 2019-Present) and the C-band frequency RADARSAT Constellation Mission (RCM, 2019-Present) synthetic aperture radar (SAR) to provide near-continual measurements of sea ice topography at the regional scale. For this study, a survey of first-year ice (FYI) and multi-year ice (MYI) in the McClintock Channel portion of the Canadian Arctic Archipelago (CAA) is completed during the winter and spring/summer seasons. RCM ScanSAR mode scenes are regionally co-located with the heights and calculated surface roughness for sea ice from Advanced Topographic Laser Altimeter System (ATLS 07) on IS-2. The IS-2 measured sea ice parameter data provide a vital cross-comparison of RCM measured backscatter variables. An object-based image analysis is used to link the IS-2 measured variables and RCM backscatter quantitatively. For data optimization, 12 bands from RCM are analyzed, including calibrated backscatter channels (HH and HV), their combinations (ratio, addition, subtraction, and multiplication), and a set of grey-level co-occurrence matrix (GLCM) based texture parameters derived from each backscatter channel, following the derivations provided in Scharien and Nasonova (2020). IS-2 ATL07 data are studied to measure sea ice surface elevation and roughness. Overall, strong positive linear relationships between backscatter and IS-2-derived surface roughness and elevation are found during the late winter (April and May) period, which supports the use of dual-polarization (HH and HV) RCM scenes and the combination of these channels (HH+HV) as complements to ATL07/IS-2 for understanding winter FYI and MYI ice topography. Generally, RCM derived backscatter is more strongly correlated to IS-2 derived variables than is RCM derived texture. At high incidence angles (>42o) and during late winter conditions, the IS-2 sea ice surface elevation from MYI strongly correlates (r ~ 0.74) with backscatter. However, the correlation between MYI surface height and RCM backscatter during winter is reduced at low and moderate incidence angles (≤42°). The relationship between RCM backscatter and FYI elevation shows a high correlation (r ~0.74 to 0.75) at low and moderate incidence angles. Considering melting conditions, relationships between IS-2 and RCM variables are much weaker compared to winter conditions, though much stronger later in the melting season (July) than earlier (June). The results of this study suggest that the following techniques should be used to map the elevation of sea ice during the winter using RCM: (1) HH-polarization backscatter (r ~ 0.74) and a low incidence angle (FYI only), and (2) HH+HV polarization (r ~ 0.64) and low incidence angle (MYI only); (3) HH+HV polarization (r ~ 0.74) and high incidence angle (MYI only); and (4) HH-HV polarization (FYI) or HV (MYI) (r ~ 0.75 and 0.72, respectively) and moderate incidence angle. Overall, HH+HV can be the best representative band for FYI topographic investigations using RCM image with low incidence angle during winter.
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    Mortality and Growth of Residual Whitebark Pine in High Elevation Variable Retention Harvest Sites in Southeastern British Columbia
    (2023-01-04) Berg, Jenny; Smith, Dan J.
    The rapid decline of whitebark pine (Pinus albicaulis) throughout its range is a pressing conservation issue. This keystone species endures multiple pressures toward local extirpation including forest health agents, forest succession, and climate change. Currently, silviculture practices are categorized as a stand-level strategy aimed at effective whitebark pine restoration/conservation. In this thesis I retrospectively evaluated the mortality and growth of whitebark pine at five low-retention ESSF silviculture treatments located in southeastern British Columbia, Canada. I found that whitebark pine reserve trees in low retention silviculture prescriptions were prone to elevated post-harvest mortality due to windthrow within the initial five-year post-harvest interval. Post-harvest growth rates indicated that mature reserve trees were likely to demonstrate increased radial growth after disturbance and that pre-harvest growth rates due to suspected forest health agents can minimize these increases. A two sample Welch t-test found no significant difference between the resistance index of control and reserve trees one year after harvest in three of the four sites examined, suggesting that radial growth reduction was negligible for surviving trees. Visual examination of the post-harvest reserve tree chronologies, however, showed a common two to three-year growth lag. Reserve trees indicated a significant difference in the recovery period for the harvest event year with a one-year lag in two of the four sites. However, this result was confounded by the following: (1) one of the sites showed a negative radial growth trend pre-harvest; and, (2) a pointer year analysis identified an inflated growth response in the control trees for the same year for the second site. These growth-climate relationships indicated that whitebark pine tree chronologies in closed-canopy forests were energy-limited systems with a significant negative correlation to July SPEI.
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    Characterizing the spatial and temporal dynamics of phytoplankton phenology in the British Columbia and Southeast Alaska coastal oceans using satellite ocean colour data
    (2023-01-03) Pramlall, Sejal; Costa, Maycira; Jackson, Jennifer
    The coastal waters of British Columbia (B.C.) support diverse food webs and provide habitats for various species of Pacific salmon, which are of vital importance to the regional economy and for First Nations culture and subsistence. To effectively monitor marine environmental health of these regions and any changes thereof, it is necessary to employ ecological indicators to provide objective and quantitative metrics upon which to evaluate the state of the ecosystem and their response to environmental and climatic perturbation. Phytoplankton phenology is an important ecological indicator that characterises the timing of annually occurring phytoplankton growing periods and has been typically synthesized into a set of indices encompassing the timing, duration, and magnitude of bloom events. Observing changes in phytoplankton phenology in this region requires vast spatial coverage and short temporal frequencies, which is achieved through ocean colour satellite imagery. Here, we evaluate the performance of the merged multi-sensor ocean colour chlorophyll-a products, GlobColour and OC-CCI, in the British Columbia coastal waters via a statistical match-up analysis and a qualitative analysis to determine whether the data reflects the region's large-scale seasonal trends and latitudinal dynamics. Using the chlorophyll-a product that is best suited to our purpose, we then derive a suite of phenological indices on a pixel-by-pixel basis, which is used to partition the study area into phenological bioregions using an objective, unsupervised partition strategy (Hierarchical Agglomerative Clustering method). The delineated bioregions are then used to describe region-specific phytoplankton phenological patterns associated with bloom magnitude, frequency, duration, and timing. The interannual variability of spring bloom initiation was evaluated considering interactions with environmental variables, sea surface temperature anomaly and the El Nino Southern Oscillation index. The GlobColour interpolated chlorophyll-a product revealed sound statistical results (r2 = 0.63, slope = 0.88, bias = 0.81, MdAD = 1.69, RMSE = 0.37, n = 797) and demonstrated the expected seasonal and local dynamics for this region, and average concentrations within ranges reported for satellite-derived observations. The derived phenology indices showed longitudinal gradients. From east to west, bloom initiation along the coast was observed in spring, gradually progressing to fall dominated blooms further offshore, with peak chlorophyll concentrations of 38.5mg.m-3 and 3mg.m-3, respectively. The spatial patterns of number of blooms per pixel has shown to be inversely correlated to average bloom duration, with lower number of blooms having longer durations and vice versa. Four coherent bioregions were identified over the study region with distinctive phytoplankton phenological properties: two coastal regions, one shelf region and an offshore region. We found that early spring blooms were associated with a positive SST anomaly and El Nino conditions. Conversely, average or late spring blooms occurred in years where there was a negative SST anomaly and La Nina conditions. Furthermore, the relationship between spring bloom initiation and principal bloom initiation was evaluated, and we found that when there is a later spring bloom initiation we can expect a later principal bloom initiation, and vice versa. The findings of this study can help better inform fisheries management and conservation programs, by being able to infer the timing of spring bloom initiation in relation to SST anomalies and ENSO index.
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    Between a ship and a hard place: Inferring fin whale behaviours and vulnerability with acoustic localizations in a fjord system
    (2022-12-19) Shine, Chenoah; Darimont, Chris; Bone, Christopher
    Large whales face increased threats from vessel traffic. Current threat mitigation strategies are difficult in constricted geographies, such as fjords, and direct observations of whales during nighttime, which can inform approaches, remains challenging. However, technological advances in whale research are also facilitating new methods to understand vulnerability during day and night. Passive acoustic monitoring, and specifically localization, provides spatial and behavioural information on species in continuous space and time. The objective of this thesis research is to examine how acoustic localizations might inform behaviour investigations of fin whale (Balaenoptera physalus) vulnerability throughout diurnal cycles. I first examined how passive acoustic localization data and species distribution modeling can be used to inform behavioural context of different fin whale calls. I then investigated the degree to which whales’ vulnerability to different vessel traffic types (associated with different threats) varies among whale behaviours. This research focuses on two call types of fin whales sensed by a four-hydrophone array on a northern latitude foraging site within Gitga'at Territory in the Pacific Northwest. This site is characterized by a narrow channel at the entrance to a fjord system and serves as a particularly relevant point of study as it faces rapid expansion of large vessel traffic in the coming decade and its constricted geography limits traditional management solutions. I found selected habitat features varied among whale behaviours, which confirmed expected social and foraging partitioning of distinct whale calls. Results also suggested potential for nighttime foraging in this area. Social calling fin whales were more vulnerable to cruise ships during daytime, while foraging callers were more vulnerable to passenger, pleasure craft, tug/towing, and fishing vessels, especially at night. It is expected that nighttime foraging callers will likely be the most vulnerable to planned increases in large vessel traffic in this region.
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    Bio-morphodynamics of the Choked Passage seagrass meadow on Calvert Island, British Columbia, Canada
    (2022-12-08) Paterson, Keegan; Kwoll, Eva
    Seagrasses are ecosystem engineers, forming extensive meadows that provide critical habitat and modulate local morphodynamics. Their canopies induce drag on flow to attenuate mean flow and reduce near-bed flow velocities, which can shield the bed from erosion and sediment suspension. Alternatively, seagrass loss can enhance erosion and sediment suspension, which can be initiated through short-lived extreme events, or chronic long-term disturbances. Physical process and disturbances can govern the evolution of seagrass meadow ecosystems. In two separate chapters, this research examined 1) the influence of climate variability and storms on seagrass loss and erosion at a high spatial resolution, and 2) how flow attenuation by seagrass varies across tidal cycles and at different locations in the Choked Passage meadow, on the Central Coast of British Columbia. We used high resolution multibeam echosounder (MBES) bathymetry and backscatter data from 2018 to 2021, drone mapped seagrass delineations from 2014 to 2021, and wind and wave data from 2014 to 2021. Flow data (i.e. velocity magnitude, velocity direction, and acoustic backscatter) above the seagrass canopy was collected with an Acoustic Doppler Current Profiler (ADCP) along transects and moored to the seafloor over a tidal cycle. Sediment samples were collected from the bed to estimate critical shear stress and verify sediment classes from an acoustic backscatter analysis. From 2018 to 2021, the meadow experienced significant erosion (net surface lowering of -18,768 m3) and loss of seagrass (10% reduction), which we attribute to the preceding winter storm activity driven by moderate La Niña conditions. The spatial patterns of erosion and seagrass loss was non-uniform across the meadow. Coupled erosion and seagrass loss resulted in the generation and/or expansion of blowouts. We observed a trend of a reduction in seagrass coverage following winters with a high number of storm events and/or high recorded storm intensity from 2014 to 2021. We believe the Choked Passage seagrass meadow undergoes cyclic behaviour with reduction in seagrass coverage during energetic ENSO years, followed by a recovery period during weak years. The ADCP was used to detect the seagrass canopy height, measure flow, and estimate shear stress. Overall, flow is fastest in the northern section of the main meadow, particularly in the north-west corner where the meadow is patchy. Moreover, flow appears to accelerate through the meadow interior, which suggests that topographic steering and the strength of incoming currents exceeds the ability of seagrass to dampen flow velocity. During the transition from peak flood to ebb, flow velocity remained heightened for longer above the southern meadow and lagged the other sections. Shear stress results indicate that sediment can be transported as bedload and in suspension under peak flow velocities at some of the sites examined within the meadow. Shear stress is largest in the meadow center and lower towards the southern margin of the main meadow. Based on our results, when sediment transport is initiated under peak tidal and/or extreme conditions, sediment is likely primarily transported as bedload, creating the observed sand wave and blowout bedforms. This research demonstrated linkages between extreme storms (during ENSO years), seabed morphology, and seagrass coverage, and examined the variability in the interaction between flow, seagrass, and sediment transport. Geomorphic processes and disturbances have an important influence on ecosystem structure and function over time, therefore, it is important to understand how these processes operate and are modified by external drivers. The results of this study have significant implications on seagrass conservation, restoration, and the evolution of coastal landscapes.
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    The influence of winter lake surface cover conditions on under-ice light regimes and primary productivity in small, hydrologically disconnected lentic systems
    (2022-11-24) Barrett, David Clem; Wrona, Frederick John; Atkinson, David
    As the Earth undergoes continued climatic change, shifts in the cryosphere are occurring at increasingly rapid rates. As a significant proportion of global freshwater is located in the mid- to high-latitudes of the northern hemisphere and is often seasonally ice covered, it is vital to understand how surface cover quality influences biological activity in these systems. Ice and surface cover conditions have been noted to be very effective at limiting light availability, and therefore influencing the photosynthetically active radiation (PAR) available for primary production. To quantify the relationship between winter surface cover and under-ice hydroecological variables, two complimentary controlled experiments were conducted over two winter periods at the University of Calgary Aquatic Experimental Facility. Above-ground polyethylene mesocosms were utilized to remove the influence of littoral and benthic activity influences on measured biological endpoints. Two paired experimental ponds, that are hydrologically disconnected and located immediately adjacent to the mesocosm enclosures were utilized to further develop the relationships, while including a slightly more complex food web structure. Surface cover manipulations were done by either adding snow (snow-on-ice), or slushing snow (white ice), and resulted in distinct differences in under-ice light regimes, dissolved oxygen (DO) levels, but not primary production measured as chlorophyll-α values. However, in the pond systems, surface cover had minimal impact on the DO levels, with both the control and treatment systems trending towards hypoxic conditions quickly after ice-on conditions, as measured using high temporal resolution probes embedded in the ponds. Chlorophyll-α levels in the pond systems, however, was significantly different with the snow-on-ice (control) pond having lower values than the pond where snow was mechanically removed, over two adjacent winter observation periods. In the second observation period, dissolved organic carbon (DOC) values were also manipulated in the mesocosm systems, with the elevated DOC systems exhibiting a decrease in DO values when compared to control systems. The utilization of controlled experimental systems and high-resolution data loggers allowed this study to offer unique insights into the relationship between ice and surface cover composition, under-ice light regimes, and corresponding biological activity under-ice. As shifts in annual winter climatic and associated meteorological conditions are predicted to continue to occur, generally towards increased precipitation and warmer mean air temperatures, the relationships derived in the study will be valuable in understanding and potentially predicting the implications of climate variability and change on seasonally ice-covered systems
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    Drivers of Change in Haida Gwaii Kelp Forests: Combining Satellite Imagery with Historical Data to Understand Spatial and Temporal Variability
    (2022-10-27) Gendall, Lianna; Costa, Maycira
    Globally, kelp forests provide the foundation of temperate coastal ecosystems through the creation of three-dimensional habitat which supports many significant economic, cultural, and ecological species. With the increasing threat of local and global anthropogenic stressors including climate change, the long-term, large-scale monitoring of kelp forests is crucial in understanding the response of these foundation ecosystems to spatio-temporal drivers in a time of rapid global change. On the coast of British Columbia, Canada, kelp forests of Macrocystis pyrifera and Nereocystis luetkeana show highly variable patterns of change, however, lack sufficient time series data to truly understand trends, threats, and drivers. In particular, Haida Gwaii, an archipelago off the main coast of British Columbia, supports some of the most expansive kelp forests in the province. However, local Haida people have observed drastic declines at traditional harvesting sites leading to the prioritization of the management, monitoring and protection of these crucial ecosystems throughout their territory. Remote sensing technology now provides an effective way to track changes and trends in remote kelp forest ecosystems at large scales like that of the Haida Gwaii coastline. Specifically, Earth Observation satellite imagery of a variety of spatial resolutions exists back to the 1970s which can be leveraged for mapping kelp forest canopies through time. This research aims to quantify the distribution, variability, and drivers of change of Haida Gwaii kelp forests with the use of satellite imagery and historical data. Specifically, to address this goal, (i) we develop a methodological framework that enables the creation of a long-term dataset of kelp canopy area using archived multispectral satellite imagery from multiple satellite sensors that vary in their spatial resolution (0.5 m – 60 m) and temporal coverage (1973-2021). To do this, we combine a workflow of standardized remote sensing practices and an adaptable image-to-image object-based classification approach to create the multi-satellite kelp mapping (MSKM) framework including an analysis of the impact spatial resolution has on the detectability of kelp forests and highlight ocean floor slope as a metric to understand uncertainties associated with using products from a range of spatial resolutions. In particular, we find that ocean floor slopes higher than 11.4 % led to high uncertainties when using medium-resolution imagery and as such, these areas were removed from further analyses. Next, (ii) we define changes in Haida Gwaii kelp forest canopy in association with drivers of change over the last 100 years using historical data (1867-1945) and medium- to high-resolution archived satellite imagery (1973-2021) at regional to local scales of analysis. Overall, kelp forest canopy area varied with low- and high-frequency climate indices where lower kelp forest canopy area occurred during warmer conditions. Additionally, patterns of kelp forests change varied across subregions where areas in the North showed considerable losses associated with a strong local gradient of sea surface temperature coupled with the cool to warm regime shift that occurred within the Pacific Decadal Oscillation in the late 1970s. In comparison, kelp forests in the cooler areas in the South showed long term resilience persisting for over a century throughout multiple heatwaves and regime shifts.