• Antibiotic resistance in a changing North: unearthing the effects of disturbance-induced permafrost thaw on the Alaskan soil resistome

      Haan, Tracie J.; Drown, Devin M.; Podlutsky, Andrej; Hueffer, Karsten; Burkhead, Jason (2021-08)
      The evolution of antibiotic resistance in pathogenic bacteria is a major threat at the forefront of public health today. By studying soils, one of the ancestral origins of antibiotic production and resistance, we can gain insight into how antibiotic resistance genes (ARGs) from the environment have contributed to the evolution and emergence of resistance in pathogens. These studies are particularly important in soils where polar amplification and human expansion has already impacted the frequency and intensity of soil disturbance events (e.g., wildfires, deglaciation, land-use). In Alaska these disturbances augment permafrost thaw shifting the biogeochemical properties of active layer soils that structure microbial community composition and hypothetically the resistome (i.e., summation of ARGs). Thus, the goal of this thesis was to assess how soil disturbance, and the subsequent shift in community composition, will affect the types, abundance, and mobility of ARGs that comprise the subarctic soil resistome. In the first chapter I cultured bacteria from a permafrost thaw gradient in Interior Alaska, tested the isolates for susceptibility to antibiotics, annotated their genomes for ARGs, and compared their resistance profiles to a global database of soil bacteria genomes. I found that phylogenic and ecological factors structured the resistome. Additionally, antibiotic resistance phenotypes and genotypes were widespread in the soil isolates suggesting resistance is an intrinsic component of bacterial evolution. In the second chapter, I used long read metagenomics to identify predominant ARGs, ARG host taxa, and the relationship between community composition and ARG abundance. From the long read data, I unearthed major trends in the types of ARGs at our study site and determined ARG abundance had a quadratic relationship with disturbance and negative relationship temporally by year highlighting the complex interplay soil conditions have in structuring the taxa that enrich ARGs in the community. To analyze how individual bacteria contribute to ARGs in the community, I generated metagenome assembled genomes (MAGs) using Hi-C proximity ligation. From the MAGs, I found a significant difference in ARGs per genome between phyla that emphasized how an enrichment of specific bacteria can affect the abundance of ARGs in subarctic soils. I also identified several plasmid-borne ARGs highlighting the potential for horizontal gene transfer. Overall, this thesis provides evidence that ARGs in permafrost-associated soil are structured by disturbance-induced community shifts. Thus, as climate change increases t the frequency of disturbance events that shift the microbial communities in active layer soils, One Health can be impacted by alterations to ARGs comprising the resistome.
    • Applicability of the Walder-Hallet frost fracture model to laboratory cyclic uni- and bi-direction freeze-thaw of limestone and sandstone

      Haas, Abram; Peterson, Rorik; Kim, Sunwoo; Zhang, Lei (2021-08)
      Due to changing climate conditions, new geographic areas are being impacted by diurnal and seasonal freezing and thawing conditions. Many geologic materials in far north latitude areas, that had not undergone significant freeze and thaw previously, are now expected to experience those conditions more often. The bedrock in these northern regions is often used as the foundation for many buildings and other infrastructure, and so it is extremely important to understand the integrity of this material with the changing conditions. Walder and Hallet created a theoretical model to analyze the temperature of fine cracks within a rock when subjected to freezing conditions, and the growth of fine cracks due to thermally-induced water migration followed by freezing. More recently, Dr. Murton conducted multiple cyclic unidirectional and bidirectional freeze-thaw experiments in the laboratory that simulated active layer rocks both with and without permafrost below. These experiments measured temperature and pore pressure of the rock, and monitored the formation and growth of macroscopic (i.e. observable) cracks. Using Walder and Hallet's model as a starting point, I have created a numerical model to analyze the cyclic fluctuating temperature conditions used by Murton in his experimental work, but is not accounted for in the original Walder and Hallet model. I then compared his laboratory results with the numerical model predictions of temperature and location of observable crack growth. This required adjusting some model parameters used by Walder and Hallet to correspond with the experimental conditions and geological materials used. I found that the model predicts the correct location of maximum cracking, and the time of observable crack growth, for the unidirectional experiments. However, it predicted nearly the opposite of the laboratory results for the bidirectional experiments. To obtain these numerical results, I had to adjust parameters that attempt to describe the flow resistance within a fine-grained freezing rock material; a difficult and little understood phenomenon. Future work should focus on improving some of the original model assumptions that do not apply to most experimental situations including those of Murton. These include the angle of cracks, and the potential interaction between adjacent cracks. While the results of this numerical model did not predict all the observed results of Murton's experiments, it has shown what portions of the numerical model appear to work correctly, and what assumptions from the original theoretical model by Walder and Hallet need to be adjusted and improved.
    • Applications of stable isotope analysis to advancing the understanding of brown bear dietary ecology

      Rogers, Matthew C.; Barnes, Brian; Welker, Jeffrey; Brinkman, Todd; Gustine, David; Hilderbrand, Grant (2021-08)
      Dietary ecology is one of the most important drivers of brown bear fitness at the individual and population levels. However, researchers do not have an in-depth understanding of the trophic niche breadth, diet composition, and seasonal diet variation for most Alaskan populations. I set out to better understand multiple facets of brown bear dietary ecology using stable isotope analysis (¹³C & ¹⁵N) as the primary tool to infer brown bear diet and gain insights into their trophic niche, dietary seasonality, dietary generalism and specialism, and isotopic trophic discrimination factors. I determined that using sectioned hair samples is the best practice for determining the isotopic trophic niche of brown bears. Additionally, I determined amino acid trophic discrimination factors for brown bears and explored the ability to separate salmon species in bear diets. I also used stable isotope mixing models with sectioned hair samples to infer seasonal dietary patterns of individual bears in five distinct Alaskan ecosystems. Approximately one-quarter of bears relied solely on vegetation over multiple years despite access to other sources of nutrition; these bears could be considered specialists. Other bears, approximately half, switched diets seasonally but had the same pattern of resource use year over year, a foraging class that I termed persistent seasonal generalism. Approximately one-quarter of bears did not have a persistent dietary pattern across years and could be considered true generalists. Most bears appear to have preferred dietary patterns that are persistent through time, which may be indicative of foraging inertia; maintaining foraging patterns even when faced with changing resource availability due to natural fluctuations, disturbance, or climate change. The sum of this work advances our understanding of brown bear dietary ecology from the individual seasonal level to population level degrees of generalism and specialism, and the methods developed can be applied to many species for which dietary ecology information is difficult to obtain.
    • Assessing adverse effects of mercury in two pinniped species

      Lian, Marianne; O'Hara, Todd M.; Rea, Lorrie D.; Kuhn, Thomas B.; Van Wijngaarden, Edwin (2020-08)
      This dissertation studies measures of adverse effects in free-ranging pinnipeds associated with relatively high total mercury ([THg]) or monomethylmercury ([MeHg+]) concentrations, relatively low total selenium ([TSe]) concentrations and/or low TSe:THg molar ratios. Both the Steller sea lion (SSL, Eumetopias jubatus) and Pacific harbor seal (HS, Phoca vitulina richardii) inhabit coasts of the North Pacific, and are considered important sentinel species for One Health (environmental, animal and human health). Relatively high [THg] is reported for some animals in both species, causing concern for adverse effects especially in the developing fetus. Maternal piscivorous diet can expose the fetus to MeHg⁺ at a vulnerable developmental stage, with potential for adverse effects on several organ systems. This dissertation focused on two of these: nervous system development and function and oxidant/antioxidant homeostasis. In Chapter 2 I outlined capture and field anesthesia of free-ranging SSL. I found faster induction times for sevoflurane over isoflurane, with a significant interaction for anesthetist. Difference among the two agents is most likely attributed to the different chemical properties for these gases (blood solubility), whereas personal experience/comfort level most likely explains the differences between the human operators. Severe hypothermia was also documented, associated with the time of year, sex and duration of anesthetic event. There was an overall low mortality rate, and the protocols were effective for relatively safe field anesthesia of a large mammal. Chapter 3 assessed oxidant/antioxidant status and associations with [THg], [MeHg⁺], [TSe] and TSe:THg molar ratio in anesthetized free-ranging SSL pups. The anesthesia protocols described in Chapter 2 were used as a physiological stressor for measuring oxidative stress in SSL. Pinnipeds as diving mammals are naturally adapted with high antioxidant activity to survive long breath-holds during foraging. However, the relatively high [THg] found in some SSL cause concern for sequestration of Se due to its high binding affinity to Hg, and subsequently decreased antioxidant capacity (Se-dependent glutathione peroxidase (GPx)). I found a significant negative relationship between lipid peroxidation and [TSe], suggesting the potential for decreased antioxidant protection from Se. There were also significant associations between increased GPx activity and lipid peroxidation, possibly protecting pups with relatively high [THg] and low TSe:THg molar ratios. In Chapter 4 I repeatedly evaluated live-stranded HS pups admitted to The Marine Mammal Center, using weekly clinical and behavior assessments, which were analyzed for associations with [THg]. There was a significant association between [THg] in hair and/or blood and decreased response to tactile stimulation, less movement and longer stays in rehabilitation. These findings will help us better assess similar [THg] in hair and blood of SSL in Alaska that we currently study as well as other pinnipeds. In summary, this dissertation confirms the potential for adverse effects in two free-ranging species of pinnipeds exposed to MeHg⁺ in utero.
    • Assessing the long-term growth response and age estimation precision for Arctic whitefishes in a rapidly changing nearshore environment

      Gatt, Kyle P.; Sutton, Trent M.; von Biela, Vanessa R.; McPhee, Megan V. (2021-05)
      Accurate monitoring of population-level health and productivity is essential for assessing the status and availability of subsistence harvested species at the forefront of climate change. This study used otolith biochronology to assess the long-term growth response of Arctic Cisco Coregonus autumnalis during a period of rapid environmental change in the Beaufort Sea region and to identify drivers of growth. A biochronology spanning 22 years (1996-2018) revealed significant interannual variation, with faster growth rates in years with warmer (R² = 0.31) and more saline (R² = 0.47) waters during the ice-free summer feeding period (July-September). These results suggested that warming may benefit Arctic Cisco. This study also compared age estimates made using fin rays, scales, and otoliths of four subsistence whitefishes (Arctic Cisco, Least Cisco Coregonus sardinella, Broad Whitefish Coregonus nasus, and Humpback Whitefish Coregonus pidschian) from the Beaufort Sea to compare the aging precision of non-lethal structures (fin rays and scales) to otoliths. Fin rays and scales provided similar age estimates as otoliths until the age of sexual maturity and underestimated otolith age for mature individuals. Scales underestimated age more often and were more difficult to which to assign age than the other two structures. Among Arctic Cisco in Alaska, fin rays and scales provided similar age estimates as otoliths for all age and size classes examined because most individuals in the study area were immature fish. These results suggested that dorsal fin rays may be used to estimate age in Least Cisco <300 mm, Broad Whitefish <450 mm, and Humpback Whitefish <350 mm, and that otoliths should remain the primary aging structure for the largest whitefishes. Overall, this research complements existing monitoring by providing evidence of an Arctic subsistence species that may benefit in part from warming and highlights non-lethal alternatives for monitoring the age structure of juvenile whitefishes.
    • Atmospheric modeling of natural hazards

      Hirtl, Marcus; Stuefer, Martin; Webley, Peter; Simpson, William; Grell, Georg (2021-05)
      Airborne hazards either in gaseous form or particulate matter can originate from a variety of sources. The most common natural airborne hazards are ash and SO₂ released during volcanic eruptions, smoke emitted caused by wildfires and dust storms. Once released into the atmosphere they can have a significant impact on different parts of the environment e.g. air quality, soil and water, as well as air traffic and ground transportation networks. This latter field is an important aspect of everyday life that is affected during hazardous events. Aviation is one of the most critical ways of transport in this century. Even short interruptions in flight schedules can lead to major economic damages. Volcanic eruptions comprise one of the most important airborne hazards to aviation. These are considered rare as compared to severe weather, but with an extremely high impact. This dissertation focusses on dispersion modeling tools and how they can support emergency response during different phases of volcanic eruption events. The impact of the volcanic ash cloud on the prediction of meteorological parameters and furthermore the dispersion of the ash is demonstrated by applying the Weather Research Forecasting (WRF) model with on-line integrated chemical transport (WRF-Chem) to simulate the 2010 Eyjafjallajökull eruption in Iceland. Comprehensive observational data sets have been collected to evaluate the model and to show the added value of integrating direct-feedback processes into the simulations. The case of the Eyjafjallajökull eruption showed the necessity to further develop the volcanic emission preprocessor of WRF-Chem which has been extended for flexible and complex ash and SO₂ source terms. Furthermore, the thesis describes how scientists could support operational centers to mitigate hazards during a large volcanic eruption event. The author of the dissertation coordinated a large exercise including experts across all Europe within a project funded by the European Union. The exercise aimed to develop and test new tools, models, and data to support real-time decision making in aviation flight planning during a volcanic crisis event. New state-of-the-art modeling applications were integrated into a flight planning software during a fictitious eruption of the Etna volcano in Italy with contributions from scientists, the military and the aviation community.
    • Beyond trending: using risking connection as a framework for moving agency culture toward trauma-informed care

      Healey, Michael J.; Renes, Susan L.; Strange, Anthony; Baker, Courtney; Anahita, Sine (2020-08)
      The prevalence and pervasive impact of adverse childhood experiences (ACEs), and more broadly, trauma, are well supported in the extant literature. Despite this evidence, there remains a significant dearth of formal training and educational programs that prepare staff who work with trauma survivors within complex behavioral health systems. Trauma-informed care (TIC) has moved beyond a trend in the mental health field and is gaining momentum as a leading philosophical paradigm that is being infused as an operational framework for agencies that work with survivors. Risking Connection (RC) is a curriculum-based training program that works with agencies interested in becoming trauma-informed. The current study examined the impact of RC on trainee outcomes for knowledge gain, attitude change, and vicarious trauma (VT) on 119 participants who all work for a therapeutic group home system being operated by a provincial government in Atlantic Canada. The findings in this study suggest that RC is effective in improving knowledge gain and attitude change in a favorable direction toward TIC. The study also supported previous findings associated with the improvement of VT.
    • Blood falls, Taylor Glacier, Antarctica: subglacially-sourced outflow at the surface of a cold polar glacier as recorded by time-lapse photography, seismic data, and historical observations

      Carr, Chris G.; Pettit, Erin; Carmichael, Joshua; Truffer, Martin; Tape, Carl (2021-05)
      Blood Falls forms when iron-rich, hypersaline, subglacially-sourced brine flows from a crack in the surface of Taylor Glacier, Antarctica. If air temperatures are low enough, the brine freezes to form a fan-shaped icing deposit. In chapter two, historical observations (including photos, oral histories, written descriptions, and field sketches) are evaluated using a confidence assessment framework to compile a history of brine icing deposit presence or absence during summer field seasons between 1903-1904 and 1993-1994. Additionally, an alternative explanation for a small, localized advance of a portion of the terminus is proposed: rather than temperature-driven ice viscosity changes, rising lake level drove temporary, localized basal sliding which induced advance, thinning, and collapse of a part of the terminus previously grounded on a proglacial moraine. In chapter three, time-lapse imagery is used to document a 2014 wintertime brine release that occurred in the absence of surface melt. This suggests that meltwater-driven fracture propagation of surface crevasses downward into the glacier was not a likely factor in this brine release event, as has been previously proposed. Further, there is no evidence for an increase in Rayleigh-wave activity prior to or during the brine release that would be characteristic of shallow seismic sources. Together, this suggests that sufficient pressure is built in the subglacial system to trigger basal crevassing and fracture propagation upward to allow brine release at the surface. In chapter four, two different seismic detectors that use ratios of short-term to long-term seismic energy variance to identify seismic events are compared. The detectors use different statistical distributions to determine what constitutes a large enough ratio to trigger an event detection. Differences between what the two detectors identify as events rather than background noise are interpreted as environmental microseismicity with a distinct diurnal and seasonal occurrence. Minimum detectable event sizes over 3-day time windows are compared. Together, these studies provide context for the history of brine release events, wintertime brine release characteristics, and descriptions of the local seismic environment at Taylor Glacier.
    • Born to burn: characterizing fuel loads, flammability and plant traits across spatio-temporal gradients of black spruce dominated communities

      Grzesik, Emilia J.; Ruess, Roger; Hollingsworth, Teresa; Turetsky, Merritt (2020-12)
      The flammability of black spruce forests is influenced by the fuel loadings and quality of fuels within a site, whereas the ability of a site to self-replace after fire, and thus forest resiliency, depends on the fire-ecological trait attributes of the plant community. Black spruce plant communities have been undergoing self-replacement succession from low to moderate severity fires for thousands of years, however, recent intensification of interior Alaska's fire regime is leading to shifts in post-fire successional trajectories, resulting in many ecological implications. This study focuses on understanding the variation in black spruce forest flammability, based on fuel load quantity and quality, and fire-ecological plant traits in 28 black spruce dominated sites ranging across age and moisture gradients in interior Alaska. I quantified tree canopy, understory and below-ground fuel loads, developed models to predict fuel loads and then utilized my measurements of above-ground fuel load quantity and quality to calculate a site-level flammability index. Based on my analyses, significantly greater flammability indices, and thus burning potential, occur in sites greater than 34 years in age, at elevations greater than 302 m and with dry site moisture, which are representative of dry, nonacidic upland black spruce and dry, acidic upland black spruce-lichen forest ecosystems. Furthermore, although fire-ecological plant trait attributes of Hylocomium splendens and Vaccinium uliginosum vary with age and moisture gradients, the amount of intra-specific trait variation within a site could not be explained by stand age or moisture and thus forest resiliency is also likely independent of age and moisture gradients. Further research is necessary to explore both abiotic and biotic explanatory variables related to intra-specific plant trait variation to better understand variation in black spruce forest resiliency on the landscape. The results from this study can assist fire managers in the prediction of black spruce forest burning potential and its vulnerability to ecosystem shift post-fire.
    • Bridging expert knowledge and fisheries data to inform assessment and management of rockfishes in the Gulf of Alaska

      Gordon, Jesse; Beaudrau, Anne; Carothers, Courtney; Williams, Benjamin (2021-08)
      Over the past few decades, nearshore rockfishes (Sebastes spp.) have experienced increased pressure from multiple fisheries throughout the Gulf of Alaska. The unique life history traits of rockfishes pose a host of challenges that make them difficult to monitor and vulnerable to overfishing. Rockfishes are economically and culturally important to coastal communities in the Gulf of Alaska. Therefore, the inclusion of fishers' knowledge in rockfish assessment and management will help to address biological goals and meet the needs of a growing fishery. This thesis examines the recent history and current management issues in nearshore rockfish fisheries in the Gulf of Alaska through triangulation of expert knowledge, fishery data, and biological surveys. We conducted semi-structured interviews with 43 fishers and agency staff who have long-term knowledge of and experience in rockfish fisheries within the Sitka and Kodiak areas. Chapter One presents a synthesis of changes in commercial and recreational rockfish fisheries since the 1970s, based on datasets from the Alaska Department of Fish and Game (ADF&G) and expert knowledge from interviews. Harvest data indicated both increases and decreases in nearshore fishing effort and harvest patterns, depending on the fishery sector, region, and rockfish species. Fishers and agency staff offered a longer-term and contextual understanding of changes in rockfish abundance. Most experts observed an overall decline in pelagic rockfishes near Sitka, AK and more variable patterns of abundance near Kodiak, AK. While many experts were hopeful about future sustainability of rockfish fisheries, others expressed concern about increases in localized fishing pressure, growth of charter fishing, barriers to access in some fisheries, and declines in rockfish biomass. Chapter Two identified institutional pathways and gaps in public engagement with rockfish fisheries management in Alaska. Fishers and agency staff highlighted the value of formal and informal institutions for effective engagement and emphasized the importance of relationship building and trust between fishers and agency staff. Fishers demonstrated stewardship over their fisheries through participation in local to state management processes, establishing norms of sustainability within fishing associations, and by taking personal actions to promote fishery conservation. Experts identified institutional gaps which included transparency issues regarding regulations, underrepresentation of recreational and subsistence harvesters in the Board of Fisheries public process, and communication barriers between the sport and commercial divisions of ADF&G. Our findings highlight the challenges of bringing together disparate data sources and the benefits of including multiple ways of knowing to produce a more complete understanding of dynamic fishery systems.
    • Bristol Bay dual permit operations, vessel heterogeneity, and the migration of Alaskan permit holders

      Gho, Marcus J.; Criddle, Keith; Adkison, Milo; Adkison, Milo; Twomley, Bruce; Brown, Benjamin (2020-08)
      This dissertation examines three aspects of Alaska's Limited Entry program. Chapter 1 explores the outcome of dual-permit regulations. The Alaska Board of Fisheries passed regulations allowing for dual permit operations in the Bristol Bay Pacific salmon drift gillnet fishery starting in 2004. These regulations allow two permit holders to fish from a single vessel with additional gear. Policymakers anticipated that the dual permit regulations would encourage young fishermen to enter the fishery and reduce the number of limited entry permits transferred from local fishermen to nonlocal fishermen and nonresidents. Statistical analyses reported in Chapter 1 indicate that the dual-permit program successfully offset part of the adverse influence of increases in the market value of permits on the number of new entrants and that implementation of dual-permit regulations was followed by a reduction in the median age of new entrants, particularly among nonresidents. However, the implementation of dual-permit regulation failed to staunch the outflow of limited entry permits. Chapter 2 examines the persistence of heterogeneity in the size of fishing vessels active in the Bristol Bay salmon drift gillnet fishery. When entry was limited, the commercial fishing fleet included a mix of vessels up to the long-established 32-foot maximum length. The race for fish that so often arises under license limitation favors the adoption of vessel and gear configurations that maximize catch-perday and could be anticipated to lead to increased homogeneity in fleet composition. Yet, statistical analyses indicate that even after over four decades, the composition of this fleet remains heterogeneous in vessel size and vessel value. Multivariate analysis of time series observations of vessel values indicates that vessels captained by permit holders who were given their permit are less capitalized than vessels captained by permit holders who purchased their permit. Likewise, vessels operated by local resident permit holders are less capitalized than vessels owned by nonlocal Alaskan or nonresident permit holders. In addition, vessels operated by older permit holders are less capitalized than vessels operated by younger permit holders. Chapter 3 examines the factors that influence the migration of permit holders. Since limitation, there have been concerns that ever more of the permits issued to individuals local to Alaska's fisheries would come to be held by individuals who were not local to the fisheries. The count of permit holders local to a fishery can change because of transfers, administrative cancellations, or because permit holders migrate either to or from fisheries where the permit is used. Chapter 3 considers possible factors that predict permit migration to or from different residency classes. Included in our analysis was a look at season length, fleet participation rates, permit transfers, the size of the fleet, gear type, wages of construction workers to serve as a proxy for substitute employment, and the local unemployment rate. Statistical analyses indicate that fisheries with longer seasons show slightly elevated migration from local to nonresident status of permit holders. Permit latency and permit holder migration have a negative relationship among the significant variables. Transfers serve as a substitute for permit migrations and provide the largest influence on permit migrations. For every resident type of migration, as the transfer rate increases, fewer permit holders migrate. The total number of permits within the fishery also affects the migration of permit holders, albeit only minimally. The second-largest influence on permit migration is gear type. Migrations to local setnet permit holders had a smaller magnitude of change than migrations from permit holders across most categories. Generally speaking, migration tends to move towards a nonresident status of permit holders. Wages of construction workers were only significant at the 5% level for transfers from locals to nonresidents and from nonresidents to locals, but both variables were positive. As the local unemployment rate increases, the rate of locals emigrating outside of Alaska increased.
    • Broad whitefish (Coregonus nasus) ecology and habitat use in Arctic Alaska: spawning habitat suitability, isotopic niches, life-history variations, and climate change risks to subsistence fisheries

      Leppi, Jason C.; Wipfli, Mark S.; Rinella, Daniel J.; Seitz, Andrew C.; Falke, Jeffrey A. (2021-08)
      Broad Whitefish (Coregonus nasus) is a critically important subsistence species for Alaska's Indigenous communities, yet little is known about the basic ecology of this species at the individual level. Understanding habitat use by Broad Whitefish is challenging due to their mobility and our limited ability to track fish throughout their lives as they move among a suite of habitats that are spatially dispersed, change over time, and are often temporary. The Arctic is undergoing major landscape and ecosystem transformation from climate change and oil and gas development, which may threaten Arctic ecosystems used by Broad Whitefish. This dissertation presents new information on the ecology of Broad Whitefish captured in the Colville River, Alaska. In Chapter 1, an intrinsic potential (IP) model for Broad Whitefish was used to estimate the potential of streams across the watershed to provide spawning habitat. Results were compared with movement patterns of radio-tagged prespawn Broad Whitefish. In Chapter 2, ecological niches utilized by Broad Whitefish were investigated via stable isotope analyses of muscle and liver tissue and otoliths from mature fish. In Chapter 3, strontium isotope (⁸⁷Sr/⁸⁶Sr, ⁸⁸Sr) otolith chronologies across individuals' lives were used to quantify life-history attributes and reconstruct migration patterns of fish. Finally, in Chapter 4, the current understanding of ongoing and future changes to the habitat, productivity, and behavior of Broad Whitefish were summarized to assess risks facing Arctic freshwater ecosystems and fishes more broadly. IP model results showed the majority of habitat with high IP (≥ 0.6) was located within the braided sections of the main channel, which encompassed > 1,548 km, and starting in mid-July, prespawn fish used habitats in the middle and lower watershed. Stable isotope analysis revealed a range of [delt]¹³C (-31.8- -21.9‰) and [delta]¹⁵N (6.6- 13.1‰) across tissue types and among individuals. Cluster analysis of muscle tissue δ¹³Cˈ, δ¹⁵N, δ¹⁸O, and δD indicated that Broad Whitefish occupied four different foraging niches that relied on marine-and land-based (i.e., freshwater and terrestrial) food sources to varying degrees across the summer period. Strontium isotopes revealed six main life histories, including three anadromous types (59%), one semi-anadromous type (28%), and two nonanadromous types (13%), suggesting greater complexity in life-history types than previously documented. Climate change is expected to continue to alter Arctic hydrology and, therefore, suitability, connectivity, and availability of habitats critical for Broad Whitefish population persistence. Warming and lengthening of the growing season will likely increase fish growth rates; however, the exceedance of threshold stream temperatures will likely increase physiological stress and alter life histories, which is likely to have mixed effects on Arctic subsistence fishes and fisheries. This information on Broad Whitefish spawning intrinsic potential, foraging niches, and life histories provides crucial knowledge to understand critical habitats used across time and space, which will help managers and conservation planners better understand the risks of anthropogenic impacts, such as climate change and oil and gas development, and help conserve this vital subsistence resource.
    • Brooks Range perennial snowfields : mapping and modeling change in Alaska's cryosphere

      Tedesche, Molly E.; Barnes, David L.; Fassnacht, Steven R.; Trochim, Erin D.; Wolken, Gabriel J. (2021-08)
      Perennial snowfields, such as those found in the Brooks Range of Alaska, are a critical component of the cryosphere. They serve as habitat for an array of wildlife, some of which are crucial for rural subsistence hunters. Snowfields also influence hydrology, vegetation, permafrost, and have the potential to preserve valuable archaeological artifacts. In this study, perennial snowfield extents in the Brooks Range are derived from satellite remote sensing, field acquired data, and snowmelt modeling. The remote sensing data are used to map and quantify snow cover area changes across multiple temporal scales, spatial resolutions, and geographic sub-domains. Perennial snowfield classification techniques were developed using optical multi-spectral imagery from NASA Landsat and European Space Agency Sentinel-2 satellites. A Synthetic Aperture Radar change detection algorithm was also developed to quantify snow cover area using Sentinel-1 data. Results of the remote sensing analyses were compared to helicopter and manually collected field data. Also, a snowfield melt model was developed using an adaptation of the temperature index method to determine probability of melt via binary logistic regression in two dimensions. The logistic temperature melt model considers summer season snow cover area changes per pixel in remotely sensed products and relationships to several independent variables, including elevation-lapse-adjusted air temperature and terrain-adjusted solar radiation. Evaluations of the Synthetic Aperture Radar change detection algorithm via comparison with results from optical imagery analysis, as well as via comparison with field acquired data, indicate that the radar algorithm performs best in small, focused geographic sub-domains. The multi-spectral approach appears to perform similarly well within multiple geographic domain sizes. This may be the result of synthetic aperture radar algorithm dependency on backscatter thresholding techniques and slope corrections in mountainous complex topography. Results indicate that perennial snowfield extents in the Brooks Range are decreasing over decadal time scales, with short-lived, interannual and seasonal increases. Results also show that perennial snowfields are more persistent at higher elevations over time with notable consistency in at least one of the Brooks Range sub-domains of this study, Gates of the Arctic National Park and Preserve. Climate change may be altering the distribution, elevation, melt behavior, and overall extents of the Brooks Range perennial snowfields. Such changes could have significant implications for hydrology, wildlife, vegetation, and subsistence hunting in rural Alaska.
    • The catalyst for contemporary jihad: the religious leaders and their strategies

      DeWitt, Ronnie; Duke, Rob; Skya, Walter; Sine, Don; Botros, Maged; Boylan, Brandon (2021-08)
      This dissertation provides insight in the methodologies utilized by leaders of jihadist terrorist organizations who create a dedicated following in their pursuit of establishing a global caliphate. The research in this project illustrates a linkage from these charismatic leaders to the sacred edicts of the Koran, the Hadith, the Sunna, Sharia (Islamic jurisprudence), and the prophet Muhammad. Moreover, it bears out a unique perspective in academic national security studies which delves deeper than similar published works regarding subject matter focused on both violent and stealth jihad (also known as the non-violent usurpation of non-Islamic cultures). These subjects are discussed in detail with real-world examples that focus on the surreptitious use of political propaganda and sustaining influence, which are key ingredients necessary to recruit empathetic followers into doing the bidding of Islamic-based terrorist organizations. Without studying the psychological aspect that motivates potential terrorists it would be a daunting task to develop countermeasures in defeating this global threat. This dissertation also reviews key literature related to this concept. This investigative study bears out a perspective that uniquely differs from any previously published work in this discipline due to the author's professional experience outside of academic research. This will become clear in chapter seven which focuses upon the infamous Day of Terror trial in the Southern District of New York Federal Court in 1995. This episode, coupled with other evidence, will prove that jihadists have been striving to establish a global Islamist caliphate by utilizing terrorism and cultural usurpation.
    • Changing glaciers in the Brooks Range and western Chugach Mountains, Alaska: mass loss, runoff increase, and supraglacial volcanic tephra coverage

      Geck, Jason; Hock, Regine; Coakley, Bernard; Dial, Roman; Loso, Michael (2020-12)
      Glaciers in Alaska cover over ~87,000 km² (~ 6 % of the state) with most glaciers thinning and retreating at an increasing rate. The thinning and retreating of glaciers worldwide can have an immediate socio-economic implication in addition to the longer-term glacier meltwater contribution to sea level rise. This dissertation investigated Alaskan glaciers in the Brooks Range for mass loss and area reductions over the period 1970-2001 (Chapter 2), historic mass balance and runoff for Eklutna Glacier, located in western Chugach Mountains, using a temperature index model over 1984-2019 period (Chapter 3), and the persistence of tephra from a volcanic eruption of Mt. Spurr in 1992 on seven western Chugach Mountain glaciers (Chapter 4). Glaciers in the Brooks Range in Arctic Alaska (> 68° N) are important indicators of climate change and provide information on long-term climate variations in an area that has few high elevation meteorological stations. Digital elevation models (DEMs) reconstructed from topographic maps were differenced from an interferometric synthetic aperture radar DEM to calculate the volume and mass changes of 107 glaciers (42 km²). Over the period 1970-2001, total ice volume loss was 0.69 ± 0.06 km³ corresponding to a mean (area-weighted) specific mass balance rate of -0.54 ± 0.05 m w.e. a⁻¹ (± uncertainty). The arithmetic mean of all glaciers' specific mass balance rates was -0.47 ± 0.27 m w.e. a⁻¹ (± 1 std. dev.). A subsample of 36 glaciers found a 26 ± 16 % mean area reduction over ~35 years. Alaska's largest city, Anchorage, is critically dependent upon the melt water of Eklutna Glacier (29 km²) for both drinking water and hydropower generation; however, the glacier is rapidly retreating. We used a temperature index model to reconstruct the glacier's mass balance for the period 1985-2019 and quantify the impacts of glacier change on runoff. Eklutna Glacier experienced a significant annual mean surface mass balance negative trend (-0.38 m w.e. Decade⁻¹). Mean annual cumulative melt increased by 24 % between the 1985-93 and 2011-19 period. Additionally, the day of the year when 95% of annual melt has occurred was eight days later in the later time period than in the earlier period, demonstrating a prolongation of the melt season. The modeled mean annual discharge increased at a rate of 0.2 m decade⁻¹. This indicates that peak water, i.e. the year when annual discharge starts decreasing as the glacier becomes smaller, has not been reached. The past increases in runoff quantity and melt season length provide opportunities for water resource managers that must be balanced against future decreased runoff as the glacier continues to shrink. Volcanic eruptions deposit volcanic tephra on glaciers in Alaska, modifying surface albedo and glacier melt. We mapped the distribution of tephra originating from the eruption of Mt. Spurr in 1992 using aerial photos and satellite imagery on seven glaciers located approximately 180 km east of the volcano in western Chugach Mountains in southcentral Alaska. The glaciers were completely covered with ≥ 500 g m⁻² tephra immediately after the event. Tephra deposits are still visible on all glaciers 26 years after the eruption. Using LandSat 8 surface reflectance bands, we quantified percentages of tephra glacier coverage. Results suggest an increasing tephra extent on five of the seven investigated glaciers over 2013-2018 period explained by firn line retreat. The mean percent increase for all glaciers was 4% with Troublesome Glacier showing greatest increase (~ 7 %) and Finch Glacier showing a slight decrease (~ 1 %). This long- term tephra persistence on glacier surfaces most likely enhanced melt although the precise effect remains unknown.
    • Characterization of water-soluble brown carbon (WS-BrC) from boreal forest wildfires in the summer season at northern high latitudes

      Banerji, Sujai; Mao, Jingqiu; Simpson, William R.; Guerard, Jennifer J. (2021-05)
      In the current study, we quantify the absorption Ångström exponent (AAE) and the mass absorption coefficient (MAC) of water-soluble brown carbon (WS-BrC) from boreal forest wildfires. We deployed a Particle into Liquid Sampler (PILS) - Liquid Waveguide Capillary Cell (LWCC)-Total Organic Carbon analyzer (TOC) system in downtown Fairbanks during the summer of 2019, to measure the light absorption by WS-BrC between around 200 nm to around 800 nm wavelength range every four minutes, and the concentration of the water-soluble organic carbon (WSOC), every two minutes. We then compute the AAE and MAC to examine the optical properties of brown carbon from boreal forest fires. During this period, several forest fires burned and we sampled particles from these fires. We explored a number of quantitative methods to compute the AAE and find that using the entire wavelength range of 300 nm to 350 nm appears to best represent the wavelength dependence of BrC absorption, in contrast to using just a pair of two wavelengths. The calculated AAE is observed to be ~3 for smaller wildfires and above ~3 for medium and large wildfires, whereas the calculated AAEnew is observed to be ~5 during the sampling of small, medium and large wildfires. The calculated MAC at 365 nm (MAC₃₆₅) tends to be ~1.0 m² g⁻¹ and remains relatively constant during wildfire events. We further compare these values to measurements reported from mid-latitude wildfires, to quantify the difference between the wildfires in Alaska and Canada from that of the wildfires in the contiguous U.S.
    • Climate change, moose, and subsistence harvest in Arctic Alaska

      Zhou, Jiake; Kielland, Knut; Kofinas, Gary; Tape, Ken D.; Prugh, Laura (2020-08)
      Arctic climate is resulting in transformative changes to Arctic social-ecological systems. With warming-induced increases in tall-shrubs, moose are expanding their range northwards. However, the socio-economic implications of this ecological change are unclear. Using field surveys, interviews, and modeling, I assessed the impact of climate change on moose harvest by hunters of Nuiqsut, an Inupiat community in arctic Alaska. Based on a 568 km transect of field sampling on shrubs and herbivore browsing levels, I estimated that the minimum shrub height for moose occurrence was ≥ 81 cm (95% CI: 65 - 96 cm). Patterns of moose geographic distribution mirrored tall-shrub distribution in arctic riparian areas. I also found that snowshoe hares may impact moose habitat via potential resource competition. Habitat suitability models, using Maxent and simpler temperature-threshold models, predicted that moose habitat may more than double by 2099 if current warming trends continue. The model outputs also suggested that climate warming will likely increase habitat connectivity, enhancing range expansion of moose in the Arctic. Finally, I used a coupled social-ecological systems (SES) framework to assess the implications of changes in tall-shrub habitat to moose harvest under future warming. Despite the expected increase in moose habitat and distribution, simulations of an agent-based model showed that the future may not translate into greater harvest opportunities, largely due to the limitation of river navigability for hunters. These findings provide an example in which rapid landscape and resource change may not translate into increased harvest. The integrated assessment with a SES framework revealed new and surprising outcomes, not evident when evaluating social and ecological components separately. This analysis highlighted how a coupled social-ecological framework can be used to assess the effects of climate change on ecosystem services.
    • Community composition and biogeography of beetles and spiders across an elevational gradient in Denali National Park, Alaska

      Haberski, Adam; Sikes, Derek S.; Hollingsworth, Teresa; Armbruster, W. Scott (2020-08)
      Anthropogenic climate change is rapidly altering alpine ecosystems in Alaska. Trees and woody shrubs are expanding upslope and displacing alpine tundra. As alpine tundra habitats shrink and fragment, arthropods and other animals face an increased risk of extirpation due to smaller population sizes and reduced geneflow. Arthropods--insects, spiders, and their relatives--are the most speciose component of the alpine fauna and perform key ecosystem services, such as pollination and nutrient cycling, and are food for vertebrates. Many species have responded by shifting their distribution to higher elevations, but species respond to change idiosyncratically, which could alter species interactions and disrupt communities. I compared beetle and spider communities along an elevational gradient in Denali National Park and Preserve, Alaska, an area with a complex biogeographic history and a poorly known arthropod fauna, in order to 1) examine differences in diversity, abundance, and community composition among forest, shrub, and alpine tundra habitats; 2) link the observed differences to abiotic factors relevant to climate change; and 3) test if shared habitat preferences lead to community-level patterns in geographic distribution. After three consecutive summers of sampling, I found that alpine tundra supports an unexpectedly diverse arthropod community with a high proportion of unique species and that vegetation cover and mean air temperature are strongly correlated with community composition. I therefore expect species losses among alpine tundra communities as shrubification continues. Community-level distribution patterns were not observed, but trends in the data point to a reduction of Holarctic distributions among forest-dwelling arthropods and an increased proportion of Beringian endemics among tundra species. This was the first systematic survey of Denali's terrestrial arthropods and added over 450 new park records.
    • A comparison of surface moisture budget and structural equation models in high latitudes: evapotranspiration and atmospheric drivers

      Thunberg, Sarah M.; Walsh, John; Euskirchen, Eugenie; Bhatt, Uma S. (2021-08)
      Arctic soil moisture is one of the most impactful and unknown aspects of the Arctic climate system. As the climate changes, surface soil moisture can impact water supplies, wildfire risk, and vegetation stress, all of which have consequences for terrestrial ecosystems and human activities. The present analysis is intended to (1) document seasonal and interannual variations of surface moisture fluxes in the Arctic region and (2) clarify the drivers of variations of net Precipitation minus Evapotranspiration (P-ET) across Arctic tundra and boreal vegetation and permafrost status. Forty-five flux tower sites were examined across boreal and tundra ecosystems across the Arctic and sub-arctic. The surface moisture budget at boreal forest sites in permafrost areas generally shows a moisture deficit in late spring and early summer, followed by a moisture surplus from late summer into autumn. The annual net P-ET is generally positive but can vary interannually by more than an order of magnitude. A factor analysis found the primary drivers of variations in evapotranspiration to be radiative fluxes, air temperature, and relative humidity, while a path analysis found windspeed to have the largest independent influence on evapotranspiration. Overall, the ET at boreal forest sites shows a stronger dependence on relative humidity, and ET at tundra sites shows the stronger dependence on air temperature. These differences imply that tundra sites are more temperature-limited and boreal sites are more humidity-dependent. Relative to nearby unburned sites, the recovery time of ET after disturbance by wildfire was found to vary from several years on the Alaska tundra to nearly a decade in the Alaska boreal forest.
    • Computational analysis of nanofluids flow and heat transfer in microchannels and fin tube air coils

      Ray, Dustin R.; Das, Debendra K.; Peterson, Rorik A.; Misra, Debasmita; Kim, Sunwoo (2021-05)
      The four goals of this dissertation were to investigate nanofluids' thermal and fluid dynamic performance in (i) an air coil, (ii) microchannel heatsink, using computational fluid dynamic (CFD) software, ANSYS Fluent, develop (iii) hydrodynamic entrance length correlation and (iv) apparent friction factor correlations in rectangular microchannels. In cold regions of the world, ethylene glycol mixed with water (EG/W) are used as a heat transfer fluid instead of water due to their freeze protection. EG/W has low thermal conductivity than water, which can be improved by dispersing nanoparticles and creating a new fluid called nanofluid. A computational scheme was developed based on the Effectiveness-Number of Transfer Unit (ε-NTU) method to compare nanofluids' thermal and fluid dynamic performance to the conventional ethylene glycol and water mixture. The nanofluid's performance was examined by conducting two studies: reducing pumping power and reducing the air coil's surface area via length. The results showed at a dilute concentration of 1% of Al₂O₃ can reduce the pumping power requirements by 35.3% or reduce the air coil length by 7.4% while maintaining the same heat transfer rate as EG/W. The results show nanofluids could provide significant savings in energy or material costs. The nanofluids' (Al₂O₃, CuO, and SiO₂) thermal and fluid dynamic performance used in a microchannel heatsink was explored using analytical and computational methods. The computational model was developed in ANSYS Fluent. Comparing analytical and computational results, good agreement was observed validating both methods. The three nanofluids had a maximum difference of 4.1% for pressure drop and 2.9% for the Nusselt number. Three performance studies were conducted using the analytical model based on constant Reynolds number, maximum surface temperature, and pumping power. A constant Reynolds number of nanofluids could reduce the maximum surface temperature by 6K, but at the cost of increased pumping power. Nanofluids showed the pumping power could be reduced by 23% compared to the base fluid while maintaining equal maximum surface temperature. In electronic cooling applications where microchannel heatsinks are used, nanofluids seem promising for lowering critical components' operating temperatures and contribute to increased life and system reliability. A detailed three-dimensional laminar flow CFD model was developed and ran for Reynolds numbers ranging from 0.1 to 1000 through six rectangular microchannels aspect ratios (α): 1, 0.75, 0.5, 0.25, 0.2, 0.125. The majority of the Reynolds numbers simulated were in the low regime (Re< 100) to fulfill the lack of literature for determining accurate hydrodynamic entrance length and apparent friction factor for microchannels. From these numerical simulations, improved correlations were developed to predict hydrodynamic entrance length with a mean error of less than 2% and a maximum error of 5.75% for 0.1 ≤ Re ≤ 1000 & 0 ≤ α ≤ ∞. For the apparent friction factor in microchannels, three correlations were derived from the numerical simulations: fully developed friction factor (fRe), developing incremental pressure drop number (K(z)), and fully developed incremental pressure drop (K(∞)). The three correlations were used to determine the local fapp,zRe, in the applicable range of 0.1 ≤ Re ≤ 1000 & 0.125 ≤ α ≤ 8. The correlations showed a mean deviation of less than 3% and a maximum deviation of less than 8.3% from the numerical data.