Recent Submissions

  • The STEM trail: Alaska Native undergraduates find the right path in higher education

    Skinner, Olga J.; Leonard, Beth; Williams, Maria; Gilmore, Perry; Mercier, Ocean (2022-05)
    The goals of this research are twofold. (1) This research explores decision making and college experiences of Alaska Native undergraduates pursuing degrees in the science, technology, engineering, and mathematics (STEM) fields, and (2) this research, using participant observation explores the Indigenous metaphor of "the trail" to frame student persistence towards their degrees. Twelve participants, representing various STEM fields, Alaska Native cultures, and K12 schooling experiences, shared their motivations and aspirations through interviews and photographs. Key findings indicate the significant role that Indigenous Knowledge plays in influencing student decisions around majoring in STEM degrees. Findings also illuminate the variety of K12 STEM experiences and the influence on decisions to major in STEM. Awareness (ellangeq) and self-authorship as student development theory, also impact decision making. The use of "the trail" as a metaphor for persistence illustrates a strength-based model for persistence, that notes the importance of the individual and the role of the individual as a community member. This metaphor also displays aspects of preparation, finding the right path, obstacles, supports, and destinations. This metaphor also calls into question the role of the institution as students work to navigate the terrain towards their degrees.
  • Marine debris in the Bering Sea: combining historical records, toxicology, and local knowledge to assess impacts and identify solutions

    Padula, Veronica M.; Beaudreau, Anne; Causey, Douglas; McDonnell, Andrew; Konar, Brenda; Hollmen, Tuula (2022-05)
    Marine debris, particularly plastic marine debris, has numerous impacts on the environment, wildlife, and human communities. This research examines dimensions of marine debris in the Bering Sea and Aleutian Islands, Alaska, including impacts of marine debris pollution on wildlife and the environment; the history of marine debris research, monitoring, and cleanup activities; and community perspectives on local to global solutions. The first chapter of this dissertation is an integrative literature review to better understand the current status of marine debris knowledge in the Bering Sea region and identify critical knowledge gaps. We synthesized the depth and breadth of research, monitoring, and cleanup activities to better understand the sources, prevalence, and impacts of marine debris on wildlife and coastal communities. Our review revealed several knowledge gaps, including two that were a focus of the final chapters of the dissertation: measuring the extent of plastic-associated contaminants in the Bering Sea and capturing community perspectives and concerns about marine debris in the Bering Sea. The second chapter examined variation in phthalates, a class of plastic-associated chemicals, in Aleutian Islands seabirds, to refine hypotheses regarding ecological and environmental factors that affect phthalate exposure in marine wildlife. We quantified phthalates in seabirds collected across >1700 km of the Aleutian Islands, Alaska, and measured six phthalate congeners in seabirds representing ten species and four feeding guilds. Phthalates were detected in 100% of specimens (n = 115) but varied among individuals (range 3.64 - 539.64 ng/g). Total phthalates did not vary geographically, but differed among feeding guilds, with significantly higher concentrations in diving plankton-feeders compared to others. Our findings suggest feeding behavior could influence exposure risk for seabirds and lend further evidence to the ubiquity of plastic pollutants in marine ecosystems. The final chapter of the dissertation explored perspectives and concerns of St. Paul Island community members regarding marine debris and plastic pollution. This component of the research aimed to catalyze the inclusion of local knowledge in marine debris solutions for St. Paul Island, Alaska, by documenting community members' perceptions of marine debris, including its origin, impacts, and proposed solutions. We interviewed thirty-six St. Paul Island community members from 2017 to 2020 about the types, amount, distribution, and impacts of marine debris they have observed on the island and its surrounding waters over recent decades. Research participants reported increases in plastic debris since the 1980s, particularly plastic bottles. Nearly 80% expressed concern about impacts to subsistence resources, including entanglement and ingestion of plastic particles by marine mammals and fishes. St. Paul Island community members' experiences highlight that solving the problem of marine debris cannot rely on local efforts alone but requires broader policies and mitigation strategies to address the sources of debris and advance environmental justice for coastal communities. Overall, this dissertation contributes an improved understanding of the social and ecological impacts of plastic pollution in the Bering Sea region and the potential science and policy solutions that can stem the tide of marine debris.
  • The linguistic dreamstate: Freud, Lacan, and intertextuality in Samuel Beckett's The Unnamable

    Kay, Michael R.; Coffman, Chris; Holt, Joseph; Carr, Richard; Brightwell, Gerri (2022-05)
    This thesis focuses on the process of symbolization and signification in Samuel Beckett's novel, The Unnamable. The introduction presents readers with important and relevant critical interpretations of the novel, primarily those that are focused on the self, the use of language, and psychoanalytic theory. Then, the thesis introduces readers to key concepts in semiotic and psychoanalytic criticism, such as that of the signifier, sign, big-O Other, and the Lacanian Imaginary, Symbolic, and Real, by applying these concepts to a reading of The Unnamable. The next section, "The Linguistic Dreamstate," argues that the novel's narrator occupies a state tangential to consciousness, subconsciousness, and unconsciousness. In occupying this state, one that is outside of physical reality, the narrator is confronted with a language he does not understand and, while speaking, seeks to understand what he has previously said, mirroring the process of psychoanalysis as it concerns the meaning of dreams. Finally, it is shown that the narrator attempts to use language to as a means to stop using language. In so doing, the narrator illustrates the inability of language (and the Symbolic) to reconstruct the Real, and the innate desire for the Real (or objet a) even in those who do not have a reality within which they see the lack of the Real.
  • Control problems for the wave and telegrapher's equations on metric graphs

    Alam, Gazi Mahmud; Avdonin, Sergei A.; Rhodes, John A.; Rybkin, Alexei; Avdonina, Nina (2022-05)
    The dissertation focuses on control problems for the wave and telegrapher's equations on metric graphs. In the first part, an algorithm is constructed to solve the exact control problems on finite intervals. The algorithm is implemented numerically to solve the exact control problems on finite intervals. Moreover, we developed numerical algorithms for the solution of control problems on metric graphs based on the recent boundary controllability results of wave equations on metric graphs. We presented numerical solutions to shape control problems on quantum graphs. Specifically, we presented the results of numerical experiments involving a three-star graph. Our second part deals with the forward and control problems for the telegrapher's equations on metric graphs. We consider the forward problem on general graphs and develop an algorithm that solves equations with variable resistance, conductance, constant inductance, and constant capacitance. An algorithm is developed to solve the voltage and current control problems on a finite interval for constant inductance and capacitance, and variable resistance and conductance. Numerical results are also presented for this case. Finally, we consider the control problems for the telegrapher's equations on metric graphs. The control problem is considered on tree graphs, i.e. graphs without cycles, with some restrictions on the coefficients. Specifically, we consider equations with constant coefficients that do not depend on the edge. We obtained the necessary and sufficient conditions of the exact controllability and indicate the minimal control time.
  • Understanding permafrost dynamics and geohazards with a terrain-cryofacies approach

    Stephani, Eva; Shur, Yuri; Doré, Guy; Darrow, Margaret; Kanevskiy, Mikhail (2021-12)
    The Arctic and its permafrost terrain are inherently dynamic, complex, and sensitive environments. Understanding the past and current changes occurring in these systems is key in predicting future variations, including the response of permafrost to climate change, and to terrain modifications resulting from natural processes or anthropogenic activities. This study contributes to advance our understanding of permafrost dynamics in varying permafrost environments of northern Alaska and northwestern Canada using a terrain-cryofacies approach. This unique approach helps to increase our understanding of permafrost dynamics from the site-specific scale to over extended areas by recognizing linkages between terrain and subsurface properties, and by identifying similar terrain units in remote sensing analysis. In the Colville River Delta (Alaska), our terrain-cryofacies study integrated data from 79 boreholes with a remote sensing analysis to evaluate the temporal changes in the Nigliq channel positions from 1948 to 2013 and the related permafrost dynamics. Most land cover changes occurred as land exposition (64%), whereas about 36% of the total changes were classified as eroded. The erosion of the older terrain units from the floodplain toposequence, such as the inactive-floodplain cover deposits, implied ground loss volumes of about one-fifth of soil solids and four-fifths of ground ice. Along this channel, we also identified the typical configuration and properties of taliks and cryopegs, as well as subsequent epigenetic permafrost growth. We found that the active channel was underlain by closed taliks, rather than through taliks and thus did not penetrate the entire layer of permafrost connecting supra- and sub-permafrost groundwater. A cryopeg connected to the active channel talik was identified from borehole data in the adjacent terrain units that developed following channel migration. We estimated the likelihood of encountering such taliks and cryopegs over extended areas. The terrain-cryofacies approach was also applied to understand permafrost dynamics of hillslope thermokarst located in multiple ecoregions of northern Alaska and northwestern Canada, including areas affected by interactions with infrastructure. Six features were studied through the combination of field-based and remote sensing methods, whereas 150 others were assessed solely by remote sensing. Studies along a pipeline indicated that embankment construction led to an increase in the active layer thickness, reaching the underlying ice-rich intermediate layer, and causing thaw settlement. This formed a thermokarst-ditch that facilitated channelization of cross-drainage water, and thermal erosion of the ice-rich permafrost that became affected by thermal denudation and caused a retrogressive thaw slump (RTS). The RTS later selfstabilized mainly due to the lateral discontinuity of massive ice (i.e., ice wedge) and the low-relief terrain. We suggested approaches to develop adaptation strategies for infrastructure at risk of RTS based on: these findings and conditions that favor or limit RTS growth by local feedbacks; considering the interaction patterns that we identified between RTS and infrastructure; and the main destabilization processes that we highlighted by terrain units. Further research is necessary, however, and must include testing potential mitigation techniques at multiple sites with monitoring programs to assess the variability in performance with respect to site-specific conditions.
  • Celebrating Alutiiq cultural revitalization: pathways to holistic individual health and community wellness

    Mete, Margaret Susan Draskovich; John, Theresa; Koskey, Michael; Counceller, April; Drabek, Alisha; Topkok, Sean Asiqłuq (2021-12)
    It is well understood that disease is a consequence of varied causation. Despite the fact that many health care providers acknowledge the importance of treating patients in a comprehensive manner in order to successfully cure sickness or alleviate symptoms, the contemporary medical system dispenses care in a fragmented and frequently incomplete manner. The essential differences between Indigenous epistemologies and the predominant Western worldview has had a more devastating impact on well-being and infirmity than is often recognized. The intention of this research is to explore the importance of promoting balanced holistic health care at a deeper and more essential level in order to address root causes, accessed through communication with the natural and spiritual realms, versus merely treating the physical expressions of illness.
  • Melt on Antarctic ice shelves: observing surface melt duration from microwave remote sensing and modeling the dynamical impacts of subshelf melting

    Johnson, Andrew Carl; Hock, Regine; Fahnestock, Mark; Aschwanden, Andy; Bueler, Ed (2021-12)
    Melt on the surface and underside of Antarctic ice shelves are important to the mass balance and stability of the ice sheet, and therefore pose significance to global sea levels. Satellite-based passive microwave observations provide daily or near-daily coarse resolution surface observations from 1978 on, and we use this record to identify days in which melt water is present on the ice sheet and ice shelf surfaces, called melt days. There are significant differences in the results of melt detection methods however, and we evaluate four different passive microwave melt detection algorithms. There is a lack of sufficient ground truth observations, so we use Google Earth Engine to build time series of Sentinel-1 Synthetic Aperture Radar images from which we can also detect melt to serve as a comparison dataset. A melt detection method using a Kmeans clustering algorithm developed here is shown to be the most effective on ice shelves, so we further apply this method to quantify melt days across all Antarctica ice shelves for every year from 1979/80 to 2019/20. The highest sums of melt days occur on the Antarctic Peninsula at 89 melt days per year, and we find few linear trends in the annual melt days on ice shelves around the continent. The primary mode of spatial variability in the melt day dataset is closely related to the Southern Annular Mode, a climate index for the southward migration of Southern Westerly Winds, which has been increasing in recent decades. Positive Southern Annular Mode index values are associated with decreased melt days in some regions of Antarctica. We also present a novel application of passive microwave analysis to detect changes in firn structure due to unusually large melt events in some regions and we show how this method detects ice lens formation and grain growth on specific ice shelves. To study the impacts of subshelf melt we focus on the Filchner-Ronne region of Antarctica, which contains the second largest ice shelf on the continent. We performed an ensemble of ice sheet model runs for a set of ocean warming scenarios. Each ensemble used a realistic range of physical parameters to control ice dynamics and sliding, generated by a Bayesian analysis of a surrogate model and observed velocities. Increased ocean temperatures were associated with increased mass loss, and by the year 2100 this region contributed 14 mm to sea level per degree of ocean warming at depth between +0°C and +4°C of ocean potential temperature. Beyond +4°C, the rate mass loss increased substantially. This mass loss corresponded to grounding line retreat across the region.
  • Rooted in environmental justice: phytogeography and ethnoecology of Serianthes

    Demeulenaere, Else; Ickert-Bond, Stefanie M.; Lovecraft, Amy Lauren; Yamin-Pasternak, Sveta; Jernigan, Kevin; Rubinstein, Donald H. (2021-12)
    Serianthes Benth. (Fabaceae) is one of the most endangered plant genera in the world, with 12 of the 18 species listed on the IUCN Red List of Threatened Species. Serianthes trees are culturally important to island communities of the Indo-Pacific region for canoes, boats, traditional houses, and medicine. Habitat loss and ecosystem degradation increased pressure on these trees, also threatening its Indigenous cosmology and traditional practices. This interdisciplinary study integrated genomic, biogeographic and ethnoecological approaches to develop appropriate policies that protect the Indigenous biocultural diversity of Serianthes. Phylogenomics of 401 nuclear exons and non-coding flanking regions using both a multi-species coalescent model and a partition gene tree analysis confirmed the monophyly of the genus and inferred the biogeography and phylogenetic relationships within Serianthes. The Guåhan (Guam) and Luta (Rota) endemic Serianthes nelsonii (known locally as Håyun lågu and Tronkon guåfi respectively) are closely related to South Pacific species. Serianthes kanehirae from Belau (Palau) and Wa'ab (Yap) are closely related to Malesian and Papuasian species. Phylogeographical patterns of Serianthes in Micronesia are discussed to inform conservation management. The ethnoecological study revealed interspecies relationships between people, animals, and plants remain strong. The traditional use of Ukall and Gumor (Serianthes kanehirae) on Belau and Wa'ab respectively remain part of Belau and Wa'ab's culture and are intertwined with rituals respecting the spiritual world. On Luta, Tronkon guåfi is an established flagship for endangered species conservation, while the last adult Håyun lågu tree on Guåhan became a rallying point for spiritual resistance when its habitat became threatened by military plans to construct a firing range. Despite its listing as critically endangered by the Endangered Species Act, its habitat is still at risk of being lost. The social movement guided by Prutehi Litekyan brought the community together to protect the Håyun lågu tree based on Indigenous belief systems. The social movement and policy research used a qualitative mixed-method approach to evaluate the dimensions of the Endangered Species Act in relation to environmental justice and biocultural rights. I concluded that a bottom-up co-management approach with polycentric networks best fits the social-cultural system of Guåhan. I propose Indigenous participation and the creation of an advisory council, comprising traditional and scientific knowledge holders, to advise on biocultural diversity preservation in the Mariana Islands.
  • 3T3-L1 adipocytes as a model of Glut4 translocation

    Collin, Aline; Duffy, Lawrence; Coker, Robert; Coker, Melynda Sheri; Drew, Kelly (2021-12)
    Type 2 diabetes (T2D), a lethal disease, reveals an alarming increase of epidemic proportions and, by 2050, an estimated 1 in 3 adults in the US will suffer from it. Persistent and systemic inflammatory and oxidative stress in adipose tissue and skeletal muscle are recognized as key players in the progression of T2D. T2D is characterized by insulin resistance, the inability of cells to respond to standard circulating levels of insulin, resulting in hyperglycemia. In adipocytes and skeletal muscle, glucose uptake, a vital step in blood glucose regulation, predominantly occurs via the glucose transporter 4 (Glut4) in an insulindependent recruitment from a cytosolic vesicle. Under inflammatory stress, these cells have demonstrated a lack of Glut4 presence in the plasma membrane, leading to a lack of glucose transport within these cells. 3T3-L1 murine adipocytes are a key model to study insulin signaling in vitro. Mature adipocytes are converted from fibroblasts in a lengthy process requiring chemical induction. Several inducers have been tested in hopes to shorten the time span required for differentiation. However, the use of different inducers and changes in the differentiation programming could have consequences on the phenotype of the mature adipocytes. For this reason, we sought to evaluate the differences in 3T3-L1 fibroblasts induced with either 3-isobutyl-1-methylxanthine (IBMX), or troglitazone. In addition to pharmaceutical recourse to restore insulin signaling and glucose uptake in cells under inflammatory duress, a dietary approach has been considered. Natural products such as blueberries have been of particular interest due to their health benefit including antioxidant benefits and their ability to modulate biochemical pathways. Wild Alaskan blueberries are of particular interest due to their link to a reduced prevalence of T2D in Alaskan Native populations. Here, we report differences in the phenotype of 3T3-L1 adipocytes based on the inducer of adipogenesis and a lack of increase in plasma membrane Glut4. Our studies demonstrate a higher expression of adipocyte biomarkers in cells treated with troglitazone compared to IBMX, but a higher expression of total Glut4 in cells treated with IBMX compared to troglitazone. In both phenotypes, we note a lack of insulin-induced increase of plasma membrane levels of Glut4 in 3T3-L1 mature adipocytes. Finally, we demonstrate an insulin-like benefit of Alaskan blueberry extracts on plasma membrane Glut4.
  • Naturally occurring etiologic factors affecting the health of breeding seabirds in the Bering Sea

    Branson, Maile; Winker, Kevin; Bortz, Eric; Causey, Douglas; Murphy, Molly; Chen, Jack (2021-12)
    Seabird populations across the globe have experienced both significant instability and consistent overall declines in recent history. Seabirds in the Bering Sea of Alaska, USA appear to be severely affected by environmental changes, exhibiting large-scale shifts in behavior and distribution and increases in unusual mortality events (UMEs) in recent years. I analyze a selection of the naturally occurring pathogenic and toxicological factors affecting breeding seabirds in the Bering Sea region using an approach focusing on zoonoses and bioaccumulating toxins. Specimens were collected at three breeding colonies in the Bering Sea in 2018 and 2019, and were evaluated for the presence of several pathogens and toxins. First, I examined the frequency of Influenza A Virus (IAV) in several understudied clades of seabird host species (n=146 individuals) across the Bering Sea. Second, I used a novel set of genetic amplification and sequencing techniques for metagenomic analysis both to determine the respiratory microbiome and to detect the presence of potentially pathogenic microorganisms in northern fulmars (Fulmarus glacialis) on St. Matthew and Hall islands (n = 15). Finally, I sought to evaluate the levels of paralytic shellfish toxins (PSTs) in the digestive tracts of northern fulmars from St. Matthew and Hall islands (n = 14). Together, these studies detected several viral and bacterial pathogens, many with zoonotic potential. These included Coxiella, Plasmodium, Toxoplasma, and IAV. PSTs were also detected in birds sampled from 2019, indicating the presence of harmful algae in the Beringian food web. The detection of these etiologic factors along with the incidence of major morbidity and mortality events suggest these birds might serve as sentinel species, indicating variations in environmental change that can pose a significant risk to both ecological stability and human health in the region.
  • Novel applications of remote sensing and GIS in mass wasting hazard assessments for two fjords of South-Central Alaska

    Balazs, Matthew S.; Prakash, Anupma; Wolken, Gabriel; Meyer, Franz; Darrow, Margaret (2021-12)
    The fjords of South-Central Alaska are dynamic environments and host to a number of natural hazards that have not received much attention from the research community. The cities of Seward and Whittier are two of Alaska's most important marine transportation hubs, home to commercial fishing fleets, termini of the Alaska Railroad, and home to thousands of residents. This doctoral research focuses on landslides and their associated hazards in these under-studied areas. Chapter 2 involves surficial mapping of the study areas and documents the role of the underlying geologic processes that threaten the safety of people and infrastructure in the Passage Canal-Portage Valley area (including the town of Whittier), to better inform community planning, mitigation, and emergency response activities. Chapter 3 builds on the successes and lessons learned from the mapping efforts made in Chapter 2. A surficial geology and landslide inventory map were made using very high resolution orthoimagery, DEMs, and 3D models which were viewed in an immersive Virtual Reality (iVR) system. Chapter 4 examines the hazards associated with large amounts of sediment entering the alluvial fan system from further upslope. A collection of six Digital Elevation Models (DEMs) and meteorological data collected over a ten-year period were used to estimate flood-related sedimentation. Uncertainties in each DEM were accounted for, and a DEMs of Difference (DoD) technique was used to quantify the amount and pattern of sediment introduced, redistributed, or exiting the system. The study shows that the DoD method and using multiple technologies to create DEMs is effective in quantifying the volumetric change and general spatial patterns of sediment redistribution between the acquisition of DEMs. Correlations of the changes in sediment budget with rainfall data and flood events were made. During the years of average rainfall, the reaches in the corridor experienced an overall decrease in sediment load, while heavy rainfall events both saw large influx of new sediment and the reworking of existing sediment. This research is the first to collect and use high resolution data for generating digital elevation models, for using a DoD method for mapping elevation changes over time, and for using these products along with available ancillary data for a hazard assessment in these regions. This doctoral work lays out a solid foundation for further work in hazard assessment that will also guide decision-makers in the future on mitigation measures in these important population centers in south central Alaska.
  • Coastal wetland carbon and mineral responses to storm and climate change through time, at Cape Espenberg Alaska

    Smith, Lindsey Michelle; Maio, Chris; Bigelow, Nancy; Eagle, Meagan (2022-05)
    The Arctic is experiencing warming and ecological shifts due to climate change and the compounded effects of polar amplification. There is a deficit of information surrounding the carbon cycle response in Arctic Alaskan coastal marsh environments to these forces. The Cape Espenberg barrier beach system has been mostly preserved through time as a shoreline-parallel, linear geometry prograding geomorphic feature. This study determines the Arctic carbon and mineral accumulation trends in marsh environments at Cape Espenberg for both paleo (pre 1850 AD) and modern (post 1850 AD) timeframes. This project makes connections between the responses of carbon and mineral materials to paleo and modern climate changes, and how this relationship may have evolved through time. Analytical analyses through radioisotope ¹³⁷Cs and ²¹⁰Pb, ¹⁴C, stable isotope spectrometry (δ¹³C), elemental (%C, %N, C:N), and dry bulk density and carbon density measurements yield a comprehensive physical and chemical dataset. Radioisotope dating techniques in the Arctic have proved challenging due to the dynamism of the environment. However, the combination of Constant Rate of Supply and Constant Initial Concentration age depth models has helped constrain ages to sediment cores even under variable conditions. Results indicate carbon and mineral accumulations have increased from paleo to modern times which indicates better growing and/or preservation conditions for organic matter (OM) under a modern climate. This agrees well with paleoclimate trends in the Medieval Climate Anomaly (MCA), and warm periods interspersed within the Little Ice Age (LIA), which correlate to greater productivity of terrestrial organic matter and isotopically lighter δ¹³C values (a terrestrial signature). Cold climate periods within the Little Ice Age correlate with increased aquatic organic matter sourcing and heavier δ¹³C values. Modern warming will likely continue to drive carbon sourcing towards terrestrial signatures as future temperatures are predicted to rise with global climate change. If the swale environments at Cape Espenberg can maintain ideal growing conditions (i.e. wet/anoxic soils and lower salinity to limit organic material decay, higher temperatures to promote growth) then Cape Espenberg will likely remain a viable carbon reservoir in the future. However, the question of whether the barrier system as a whole will continue to prograde under a regime of rising sea levels and increased storm impacts is unclear. The results of this study contribute towards understanding the dynamism of Arctic coastline mineral and carbon cycling and their ecological response to the current warming climate.
  • Acoustic detection and characterization of sea ice and surface waves in the northeast Chukchi Sea

    Sandy, Savannah J.; Danielson, Seth; Iken, Katrin; Mahoney, Andy; Simmons, Harper (2022-05)
    Monitoring the status of Arctic marine ecosystems is aided by oceanographic moorings that autonomously collect data year-round. Near Hanna Shoal in the northeast Chukchi Sea, the Chukchi Ecosystem Observatory moorings include an ASL Environmental Sciences Acoustic Zooplankton Fish Profiler (AZFP) datalogger, a multi-frequency upward-looking sonar that is programmed to collect data from across the upper 30 m of the water column every 10-20 seconds. Using six years of nearly continuous data, here we describe a statistical analysis of the datalogger's 455 kHz acoustic backscatter return signal. When used in conjunction with a selforganizing map machine learning algorithm, these data allow us to accurately differentiate between the presence of sea ice and open water and characterize surface waves. The approach detects short-duration (e.g., 15 minutes or longer) sea ice leads that pass over the mooring in winter, and sparse ice floes that pass over in summer. The ability to algorithmically identify small-scale features within the information-dense acoustic dataset enables rich characterizations of sea ice conditions and the ocean surface wave environment. Example applications include quantifying the recurrence of leads during ice-covered seasons, sparse ice in otherwise open water, statistics of ice keels and level ice, and wave height statistics. By automating the acoustic data processing and alleviating labor- and time-intensive analyses, we can maximize the use of these year-round acoustic data. Beyond applications to newly produced datasets, the approach opens possibilities for the efficient extraction of new information from existing upward-looking sonar records from recent decades.
  • Theory, design, and development of an open-source 3D printed peristaltic pump for microfluidics applications

    MacEachern, Joshua M.; Chen, Cheng-fu; Peterson, Rorik; Huang, Daisy; Laughlin, Bernard (2022-05)
    Microfluidics research is a constantly evolving and developing field of research in the biological, chemical, and medical sciences. To perform microfluidic analyses, various types of pump designs have been developed or optimized. These pumps are generally capable of pumping flow in the range of 0.1-100s of microliters (µL) per minute, with the goal of pumping fluid with an extremely consistent flow rate. These pumps include, but are not limited to, peristaltic, syringe, membrane, and lobe pumps. Both commercial and open-source designs have been developed to meet the needs of continued research. Commercial designs are very expensive, but offer limited flexibility to tailor the usage for custom assays. Open-source designs that have been presented may lack support, or may be designed to use fabrication technologies that are less commonly available than conventional desktop 3D printing. Due to this, many laboratories may be limited in their microfluidic research work due to either availability of commercial pumps, or usability of open-source pump designs. This work presents two iterations of a novel design for a 3D-printable microfluidic peristaltic pump. The pumps developed herein have been tested to demonstrate consistent performance operating over long-term periods of up to ten days continuously. These pumps have been tested to demonstrate capability of delivering aqueous flow as slow as flow ranges of 10s of µL/min. These pumps are capable of maintaining an outlet pressure of up to 220 kilopascals (kPa). In a tube of 1 mm inner diameter, this pressure would drive a flow rate of 10 µL/min through tubing up to 6.6 meters long. Finally, this design has been optimized to improve the user experience and make these peristaltic pumps both easy to maintain and easy to operate by a non-technical user.
  • Assessing the demographic and genetic contributions of precocial males in a naturally spawning population of coho salmon

    King, Erika M.; McPhee, Megan; Tallmon, David; Vulstek, Scott; Cunningham, Curry (2022-05)
    Despite the importance of alternative life history strategies to population productivity, little is known about the mating structure of precocial ('jack') males in Pacific salmon. The number of successful matings obtained by jacks in the wild is not well characterized and the impact of including or excluding jacks in the management of Pacific salmon populations is unknown. This study aims to fill knowledge gaps in the understanding of jack life history by 1) determining the typical contribution of jacks to the next generation in a natural mating population; and 2) estimating the impact of jacks on genetic diversity. The study capitalizes upon 11 years of demographic and genetic data from a naturally spawning population of Coho Salmon from Auke Creek, in Juneau, Alaska. Individuals returning over this time period (~8,000 individuals) were genotyped at ~250 single-nucleotide polymorphism (SNP) loci. Using these genotypes, we quantified the adult-to-adult reproductive success of different male types using parentage analysis for each of seven return years and compared genetic and demographic estimates of effective population size. We demonstrated that although jacks were less successful than full-size males on a per individual basis, they contributed substantially to the population and influenced population and evolutionary dynamics.
  • Technical and economic evaluation of the first ever polymer flood field pilot to enhance the recovery of heavy oils on Alaska's North Slope via machine assisted reservoir simulation

    Keith, Cody D.; Zhang, Yin; Ahmadi, Mohabbat; Dandekar, Abhijit (2022-05)
    Polymer flooding has become globally established as a potential enhanced oil recovery method for heavy oils. To determine whether this technology may be useful in developing the substantial heavy oil resources on the Alaska North Slope, a polymer flood field pilot commenced at the Milne Point Unit in August 2018. This study seeks to evaluate the results of the field pilot on a technical and economic basis. A reservoir simulation model is constructed and calibrated to predict the oil recovery performance of the pilot through machine-assisted reservoir simulation techniques. To replicate the early water breakthrough observed during waterflooding, transmissibility contrasts are introduced into the simulation model, forcing viscous fingering effects. In the ensuing polymer flood, these transmissibility contrasts are reduced to replicate the restoration of injection conformance during polymer flooding. Transmissibility contrasts are later reinstated to replicate fracture overextension interpreted in one of the producing wells. The calibrated simulation models produced at each stage of the history matching process are used to forecast oil recovery. These forecasts are used as input for economic analysis, incremental to waterflooding expectations. The simulation forecasts indicate that polymer flooding significantly increases the heavy oil production for this field pilot compared to waterflooding alone, yielding attractive project economics. However, meaningful variations between simulation scenarios demonstrate that a simulation model is only valid for prediction if flow behavior in the reservoir remains consistent with that observed during the history matched period. Critically, this means that a simulation model calibrated for waterflooding may not fully capture the technical and economic benefits of an enhanced oil recovery process such as polymer flooding. Subsequently, the simulation model and economic model are used in conjunction to conduct a sensitivity analysis for polymer flood design parameters, from which recommendations are provided for both the continued operation of the current field pilot and future polymer flood designs. The results demonstrate that a higher polymer concentration can be injected due to the development of fractures in the reservoir. The throughput rate should remain high without exceeding operating constraints. A calculated point-forward polymer utilization parameter demonstrates the decreasing efficiency of the polymer flood at later times in the pattern life. Future projects will benefit from starting polymer injection earlier in the pattern life. A pattern with tighter horizontal well spacing will observe a greater incremental benefit from polymer flooding.
  • Interpretations of climate change on grazing systems: the comparison of Arctic and Subarctic carex

    Harritt, Iris Cato; Wolf, Diana; Ruess, Roger; Takebayashi, Naoki; Flint, Paul (2022-05)
    Stresses imposed by climate change are altering arctic and subarctic ecosystem structure and function. On the Yukon-Kuskokwim River Delta (YKD) in subarctic western Alaska, Pacific Black Brant geese (Branta bernicla nigricans) are losing their available grazing lawns of shortstatured Carex subspathacea due to its conversion into a taller, less nutritious growth form. However, C. subspathacea on Alaska's Arctic Coastal Plain (ACP) grows in extensive lawns that remain short even when ungrazed. Our goal was to compare the growth responses between arctic C. subspathacea and subarctic C. subspathacea when grown in arctic and subarctic conditions. We used reciprocal common gardens to study the variation in height, tiller density, aboveground biomass, and green leaf nitrogen percentage between these reputed taxa. We explored the growth responses that occur in C. subspathacea when grown in the arctic and subarctic using linear mixed effect models. We found that environmental differences between these regions influence the morphology of these taxa. Subarctic C. subspathacea is phenotypically plastic, and was able to grow tall in subarctic conditions, while remaining short in the Arctic. However, arctic C. subspathacea was short in both gardens, suggesting arctic C. subspathacea will not grow tall under warming conditions. Understanding the functional causes of the difference between these two grazing systems is important for predicting the effects of future climate change on both regions. This study provides insight to how changing climate will impact these different growth forms and affect future grazing dynamics along arctic and subarctic coasts.
  • Application of probabilistic decline curve analysis to unconventional reservoirs

    Egbe, Uchenna C.; Awoleke, Obadare; Goddard, Scott; Ahmadi, Mohabbat (2022-05)
    This work presents the various probabilistic methodology for forecasting petroleum production in shale reservoirs. Two statistical methods are investigated, Bayesian and frequentist, combined with various decline curve deterministic models. A robust analysis of well-completion properties and how they affect the production forecast is carried out. Lastly, a look into the uncertainties introduced by the statistical methods and the decline curve models are investigated to discover any correlation and plays that otherwise would not be apparent. We investigated two Bayesian methods - Absolute Bayesian Computation (ABC) and GIBBS sampler - and two frequentist methods - Conventional Bootstrap (BS) and Modified Bootstrap (MBS). We combined these statistical methods with five empirical models - Arps, Duong, Power Law Model (PLE), Logistic Growth Model (LGA), and Stretched Exponential Decline Model (SEPD) - and an analytical Jacobi 2 theta model. This allowed us to make a robust comparison of all these approaches on various unconventional plays across the United States, including Permian, Marcellus, Eagle Ford, Haynesville, Barnett, and Bakken shale, to get detailed insight on how to forecast production with minimal prediction errors effectively. Analysis was carried out on a total of 1800 wells with varying production history data lengths ranging from 12 to 60 months on a 12-month increment and a total production length of 96 months. We developed a novel approach for developing and integrating informative model parameter priors into the Bayesian statistical methods. Previous work assumed a uniform distribution for model parameter priors, which was inaccurate and negatively impacted forecasting performance. Our results show the significant superior performance of the Bayesian methods, most notably at early hindcast size (12 to 24 months production history). Furthermore, we discovered that production history length was the most critical factor in production forecasting that leveled the performance of all probabilistic methods regardless of the decline curve model or statistical methodology implemented. The novelty of this work relies on the development of informative priors for the Bayesian methodologies and the robust combination of statistical methods and model combination studied on a wide variety of shale plays. In addition, the whole methodology was automated in a programming language and can be easily reproduced and used to make production forecasts accurately.
  • Spatial and temporal variability of fish and mussel distributions revealed through eDNA metabarcoding

    Dokai, William; McPhee, Megan; Larson, Wesley; Tallmon, David; Zanatta, David (2022-05)
    Unionid mussels (order Unionida) are freshwater bivalves distributed worldwide and are among the world's most endangered taxonomic groups. Unionid mussels utilize various fish species as obligate hosts for their parasitic larval stage, and as a result, native fish species are vital to unionid persistence. One of the primary conservation needs for both unionids and fishes is more complete distributional data. However, these data are labor and resource intensive to collect using traditional survey methods. Here, we utilized an eDNA metabarcoding approach to detect unionid mussels and fishes within a large portion of the lower peninsula of Michigan, USA, with the goal of validating this method for the paired detection of these two groups of taxa. We investigated whether communities of fishes and mussels varied between the tributaries of Lake Michigan and the Grand River watershed, between early- and late-summer sampling events, and between areas of high and low mussel diversity. We detected 21 unique mussel taxa and 46 unique fish taxa within the Grand River watershed and 20 Lake Michigan tributaries. We detected differences in fish and mussel communities across different sampling regions and between sampling events. We also found fish taxa associated with areas of high and low mussel diversity. Notably, we detected more mussel taxa within the Grand River watershed compared to Lake Michigan tributaries, more fish in the August sampling event compared to June, three fish taxa more frequently at areas of high mussel diversity, and four fish taxa more frequently at areas of low mussel diversity. This study demonstrates the utility of combining unionid and fish metabarcoding primers to efficiently describe the co-distribution of these interdependent taxa within the Great Lakes region.
  • Lipid accumulation in three species of Neocalanus copepod in the northern Gulf of Alaska

    Coleman, Delaney M.; Hopcroft, Russell; Danielson, Seth; Hennon, Gwenn (2022-05)
    The Northern Gulf of Alaska experiences pronounced seasonality and inter-annual variability characterized by a significant bloom of phytoplankton in the spring. Neocalanus copepods in the NGA have evolved to match their lifecycle to the seasonality of the Gulf of Alaska and feed upon the spring phytoplankton bloom. All three of these Neocalanus species utilize diapause as an over-wintering strategy; acquiring large stores of lipid to sustain them through winter hibernation and subsequent reproduction. Zooplankton were sampled with 150 and 505 µm mesh nets from 0 to 1200 m along the Seward Line and within Prince William Sound in the Northern Gulf of Alaska during 2018-2020 to track the physiological process of Neocalanus copepods preparing for diapause. We measured lipid sac area, lipid volume and percent lipid to quantify lipid content. Neocalanus showed significant interannual variability in final lipid accumulation both at depth and in the surface during the study period. For all three species, lipid content increased with increasing stage and prosome length. Lipid content increased from spring to summer for N. flemingeri, remaining steady into fall as animals molted into adults and descended to depth for diapause. Neocalanus plumcrhus stored lipid from spring to summer before descending slightly after N. flemingeri. Neocalanus cristatus exhibited dissimilar behavior to the other two species, storing consistently low amounts of lipid, alluding to a different lifecycle. Each Neocalanus species displayed similar lipid accumulation behavior with offset timing from one another. Neocalanus exhibits an earlier developmental timing as compared to other lipid accumulating copepods giving them a competitive advantage to reach maturity in time to feed on the early phase of the spring phytoplankton bloom faster than other species. Our data provided some evidence for both the lipid accumulation hypothesis and the developmental program hypothesis being utilized in Neocalanus populations in the Northern Gulf of Alaska. This work serves as the first detailed study of body condition and lipid sac condition in Neocalanus populations throughout the water column within the Northern Gulf of Alaska.

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