• Design, manufacture, and testing of a modular array for three-dimensional photovoltaics

      Fiscus, Trevar; Peterson, Rorik; Huang, Daisy; Denkenberger, David (2020-08)
      The emerging technology of three-dimensional photovoltaics is explored, shedding light on past research, current developments, and recommendations for future work. Research was performed at the University of Alaska Fairbanks analyzing six different geometric configurations of solar cells, both computationally and experimentally. The primary work described in this paper is the design and production of a modular solar array prototype and the experimental setup used to test the power output of the different configurations. Data collected from hundreds of tests were processed and analyzed to find optimum configuration angles and recommendations for future research. Working through the process of designing and manufacturing the equipment, and then subsequently using it for experimentation, provided many insights into recommended improvements. This text is organized into eight chapters that detail the background of research in using three-dimensional space for solar power generation, the recent project completed at the University of Alaska Fairbanks, and the proposed guidance for future work on this topic. This paper and use of the sources cited herein should provide the reader with the background and tools necessary to continue research. The latter chapters should act as a guide for the future design of components to be used in laboratory experimentation. It is hoped that this report, the collected data, and associated files from this project will add to the knowledge base of threedimensional solar arrays and help advance the technology one step closer to real-world application.
    • The development and initial testing of the vertical comet assay, a novel technique for the study of DNA damage and repair

      Williams, Robert T. D.; Pdlutsky, Andrej; Chen, Cheng-fu; Drew, Kelly (2021-05)
      Gene-specific repair is the idea that certain segments of the genome repair at a faster rate than others. This idea, if demonstrated with adequate evidence, would have large implications for the field of biology as a whole, with special significance for the fields of oncology, gerontology, and molecular and cell biology. The concept of gene-specific repair is not new, with the earliest references in the literature dating back to 1985, and there is a small volume of evidence derived over the years. However, the evidence generated so far is not enough to conclusively prove the existence of gene-specific DNA repair. Generally, the reason for the lack of evidence is that currently available assays and techniques are not adequate for the study of gene-specific repair on a large scale as the techniques that are available require a great deal of time, funding, and skill to generate a reliable and conclusive data set for a single gene, let alone the entire genome. The vertical comet technique described here-in is a response to the perceived need for a robust and relatively high-throughput technique for the study of gene-specific DNA repair. In the traditional comet assay, cells are fixed in agarose gel. Electrophoresis is performed, following several treatment steps, to create a ball of nuclear material embedded in the agarose gel with a 'tail' of smaller pieces of nominally damaged DNA extending to one side. The vertical comet captures this tail DNA in a buffer, allowing for its further analysis with processes such as quantification, PCR/qPCR, and sequencing. The capture of the tail DNA not only makes genespecific repair studies possible, it also allows the vertical comet to fulfill the role of the traditional comet assay with a number of advantages - a reduction in human bias, a reduction in labor-hours required for work, and a reduction in inter-lab variability of results.
    • Development of a vertical oscillator energy harvester: design and testing of a novel renewable resource power conversion system

      Wise, Michael A. Jr.; Al-Badri, Maher; Wies, Richard Jr.; Kasper, Jeremy (2020-12)
      Remote Alaska communities have historically dealt with elevated electric power expenses due to high cost of transporting diesel fuel for power generation. To offset this cost, the installation of various renewable resources have been utilized, particularly wind and solar power. Hydrokinetic generation by harnessing river flows is an emerging and less commonly implemented renewable resource that offers great potential for power generation. Specifically, this study investigates the behavior of a novel concept for harnessing vertical oscillation that occurs when a bluff body is inserted into a flow path. Unlike traditional rotating turbines used in hydrokinetic energy, this particular device utilizes the fluid structure interactions of vortex-induced-vibration and gallop. Due to the unique characteristics of this vertical motion, a thorough examination of the proposed system was conducted via a three-pronged approach of simulation, emulation, and field testing. Using a permanent magnet synchronous generator as the electrical power generator, an electrical power conversion system was simulated, emulated, and tested to achieve appropriate power smoothing for use in microgrid systems present in many Alaskan rural locations.
    • Development of scalable energy distribution models to evaluate the impacts of renewable energy on food, energy, and water system infrastructures in remote Arctic microgrids of Alaska

      Karenzi, Justus; Wies, Richard; Huang, Daisy; Al-Badri, Maher (2020-08)
      Experience and observations from remote Alaska communities have shown that energy is inarguably at the center of food, energy, and water (FEW) security. The availability of potable water, fresh produce, food storage, or processed seafood ultimately depends on a reliable and adequate energy supply. For most communities, diesel fuel is the primary source of power, which comes at high cost because of the logistics associated with importing the fuel to these relatively isolated communities. Integrating locally available renewable energy resources not only enhances energy supply, but the impacts further translate to food and water security in remote microgrids. The focus of this work is to investigate how intermittent renewable energy sources impact community level food and water infrastructure systems in a remote Arctic microgrid. Energy distribution models are mathematically developed in MATLAB® Simulink® to identify, describe, and evaluate the connections between intermittent renewable resources and the FEW loads. Energy requirements of public water systems, greenhouses, cold storage units, seafood processing loads, and modular water and food system loads are evaluated. Then energy sources including solar PV, solar thermal collectors, wind, hydro, energy storage, and diesel electric generation are modeled and validated. Finally, simulations of scenarios using distributed energy resources to serve water and food infrastructure loads are carried out including the incorporation of dispatchable loads. The results indicate that the impacts of renewable energy on FEW infrastructure systems are highly seasonal, primarily because of the variability of renewable resources. The outcome of this work helps in gaining firsthand insights into FEW system dynamics in a remote islanded microgrid setting.
    • Development of working fluid control techniques for improved ramping response in geothermal-based organic Rankine cycle generation systems

      Shofowora, Abayomi John; Wies, Richard; Denkenberger, David; Al-Badri, Maher (2021-05)
      Small-scale low-temperature geothermal-based electricity generation systems are under development for use as grid supporting and grid forming power sources in remote locations. Conversion of low-temperature heat to electrical energy in an organic Rankine cycle using working fluids such as refrigerants is challenging due to the low energy conversion efficiency of the process and the significantly slower thermal response rate in comparison to the time response of the electrical grid for changes in electrical generation and load. There is a need to investigate techniques for controlling the flow of the working fluid in combination with the use of a secondary heat exchanger to improve ramping response of these systems. This research project develops and models a working fluid control technique that incorporates power electronic technologies that could help to improve the ramping response of geothermal-based organic Rankine cycle generation systems. The performance of the model is examined with the aid of simulations in MATLAB® Simulink®. The results from these simulations are used to develop a functional and reliable control technique for ramping response improvement in geothermal-based electricity generation systems using organic Rankine cycles.
    • Drivers of life history variation in a long-lived, marine predator: individual heterogeneity in reproductive performance of grey seals (Halichoerus grypus)

      Badger, Janelle Jean; Breed, Greg; Bowen, W. Don; Doak, Pat; Mueter, Franz; Kitaysky, Alexander (2021-08)
      Fitness variation among individuals is a key tenet of eco-evolutionary theory, as natural selection acts upon this variation to bring about evolutionary change. Our understanding of individual heterogeneity and its evolutionary consequences in wild populations is limited, particularly for long-lived animals which are difficult to observe on a biologically relevant scales. This dissertation explores the dynamics of reproductive heterogeneity in a long-lived, iteroparous animal stemming from individual variation, energetic trade-offs, and ecological conditions using over 35 years of longitudinal data on a large sample of marked female grey seals (Halichoerus grypus) breeding on Sable Island, Nova Scotia. Using mixed-effects regression and novel mark- recapture techniques, I investigate three topics. First, I evaluated the evidence for and structure of individual heterogeneity in reproductive performance and determined how this heterogeneity interacts with increasing population size. In particular, I assessed whether population density affects individual-level reproduction, and may alter or amplify differences among individuals. Next, I investigated the relative contributions of individual heterogeneity and energetic trade-offs as drivers of life history variation by exploring the relationship between age-specific reproductive performance and survival. Finally, I determined how physical characteristics in early ontogeny may be a source for individual variation in reproductive success. Overall, I showed that individual heterogeneity is a prevalent and important feature of the Sable Island breeding population that interacts with ecological conditions. Variation among individuals in reproductive ability appears to be a main driver of variation in life history trajectories, and this variation may in part stem from physical characteristics and conditions during early ontogeny. These results have important implications for future demographic and ecological analyses on this population as it reveals that individual variation cannot be ignored to accurately estimate vital rates and underlying individual trade-offs. This work is one of few on long-lived marine mammals and may provide insights into drivers of life history variation of other systems of long-lived, iteroparous animals that are not so well observed.
    • The effect of sea otter predation and habitat structure on nearshore crab assemblages in Southeast Alaska

      Cates, Rebecca Jeanette; Eckert, Ginny L.; Cunningham, Curry; Siddon, Christopher (2022-05)
      Sea otter Enhydra lutris predation has resulted in conflict with humans for shared marine resources, as sea otters reduce the abundance and size of nearshore crabs. Several species of crab in Southeast Alaska are prey for sea otters including Cancer magister, a highly valued commercial and subsistence species, as well as Cancer gracilis, Cancer productus, and Telmessus cheiragonus, species that are abundant in the nearshore and of ecological and subsistence importance. Understanding the influence of sea otters and habitat structure on valuable crab species is of particular importance in Southeast Alaska as the abundance and range of sea otters expands across important crab nursery habitat. We 1) conducted breakpoint analyses to identify sea otter density thresholds that affect the abundance and biomass of nearshore crab species, 2) used a two-factor type III Analysis of Variance (ANOVA) to test the impact of sea otter presence and year on crab size, and 3) used general linearized models (GLM) to test the impacts of sea otter density and habitat structure on crab species abundance and size distribution. We found evidence of sea otters decreasing crab species' abundance, biomass, and size. C. magister, C. gracilis, and C. productus experienced a significant decline in size in the presence of sea otters, while T. cheiragonus size did not differ as a function of sea otter presence. We found a significant decrease in biomass in C. magister and in biomass and abundance in C. productus, associated with increasing sea otter density. Different responses across crab species are likely attributed to size distributions and sea otter foraging behavior. Habitat characteristics, such as eelgrass biomass and shoot density, had a small influence on crab abundance and size that depended on the species of crab. These results suggest that populations of large crabs do not persist in the presence of sea otters, small crabs may co-occur with sea otters, and eelgrass biomass and density marginally influence crab abundance and size.
    • The effect of Siberian alder on the activities of three extracellular enzymes and their implications for soil decomposition in Arctic and boreal Alaska

      Heslop, Calvin; Ruess, Roger; Bret-Harte, Syndonia; Kielland, Knut (2020-08)
      As tall shrubs increase in extent and abundance in response to a changing climate, they have the potential to substantially alter ecosystem nutrient availability and carbon (C) balance. Siberian alder (Alnus viridis ssp. fruticosa), a nitrogen (N) fixing shrub, is among the species responding to climate warming in both the Arctic and boreal forests. Alder-fixed N has the potential to increase decomposition of labile C, by relieving N limitation on microbial activity. Simultaneously, it has the potential to decrease decomposition of recalcitrant C by downregulating microbial N mining. The net effect of N additions is influenced by the relative quality of the soil C and could determine whether alder N additions result in a net sink or source of C to the atmosphere. We measured the activities of three extracellular enzymes in bulk organic soils under and away from alder canopies, in stands differing in soil organic matter quality, in both arctic and boreal forest regions of Alaska, USA. In the Alaskan arctic, the proximity of alder increased the activities of both recalcitrant and labile C-degrading enzymes regardless of soil C quality, potentially resulting in increased C losses. In the boreal forest, enzyme activities did not differ with alder proximity nor stand soil C quality, possibly due to long legacies of alder N inputs relieving microbial N limitation in these stands. As arctic and boreal forest ecosystems experience shifts in the distribution and abundance of this N fixing shrub, alders' influence on soil decomposition could have significant consequences for high latitude soil C budgets.
    • Effectiveness, environmental pathways and operational readiness of OP-40 chemical herder when used in conjunction with in-situ burning for oil spill reponse in the offshore Arctic

      Bullock, Robin J.; Perkins, Robert A.; Aggarwal, Srijan; Schnabel, William; Barnes, David; Allen, Alan (2021-05)
      The Arctic is the northern most part of the Earth, and within Alaska (United States), is home to approximately 10,000 people, the majority of which are indigenous populations. It contains some of the largest reserves of natural resources and the most extensive and continuous wilderness areas in the world. As the Earth's climate changes, so does the Arctic and its economy, its commercial opportunities as well as the associated risks. One such risk is the unintentional release of oil into the offshore Arctic environment from resource extraction, commercial fishing, tourism or marine shipping. Oil spills in this environment prove damaging to the marine population, as well as logistically challenging given the remote landscape, harsh temperatures, ice cover and difficult working conditions. The primary oil spill response methods are mechanical recovery, chemical dispersion, and/or in-situ burning. Regarding possible spills in Arctic seawaters, the choice of response option depends on ice cover, along with other factors. In-situ burning is a possible primary response option if the oil slick is thick enough to sustain burning and may be one of the few options available for use in ice-covered waters. Chemical agents, known as thickening agents or "herders", may enhance the opportunities for in-situ burning by temporarily thickening of the oil slick in order to sustain a burn. With careful evaluation of the physical and chemical processes involved with herder application and subsequent burning and their ultimate fate within the environment; industry, government, Alaska native and other interested parties would be better able to assess the usefulness of this response option and judge the safety and effectiveness of herder use in the Arctic, as well as estimate its effects on the environment.
    • The effects of individual and environmental heterogeneity on long-term population dynamics of Cassin's auklets (Ptychoramphus aleuticus)

      Johns, Michael E.; Breed, Greg; Lindberg, Mark; Kitaysky, Alexander; Doak, Pat (2020-12)
      Reproductive output and survival are expected to be balanced through a tradeoff between current success and future potential, in response to environmental conditions that vary on spatial and temporal scales. Long-term datasets that follow uniquely marked animals through time are excellent tools for describing how heritable or derived traits that influence reproduction and survival can be attributed to individual quality, and how the added reproductive performance of these individuals influence population dynamics. A 37-year record of breeding histories from known-aged Cassin's auklets from Southeast Farallon Island, a colony off the coast of central California, was used to examine these ideas in the context of a behavior unique to long-lived birds called double brooding. The results of generalized linear mixed modeling and multistate mark-recapture models revealed that double brooding, a form of increased immediate breeding effort, was associated with both higher reproductive output and longer lifespans. Older individuals that initiated breeding early in the season were most likely to attempt a second brood, particularly when food availability was high. Multistate mark-recapture analyses showed individuals that double brooded many times throughout their lives incurred no apparent longterm costs to survival or longevity. Oceanographic conditions related to prey abundance in the summer months affected the rates of double brooding, and using three years of movement data were shown to be important drivers of winter habitat selection as well. Findings at the individual level present strong evidence of a positive relationship between double brooding and survival that can only be attributed to some measure of individual quality. At the population level, when competition for breeding sites was relaxed, higher rates of double brooding had a positive effect on future recruitment rates; buffering the population against climate-driven periods of low adult survival.
    • The effects of ocean acidification and warming on the metabolic physiology of juvenile northern spot shrimp (Pandalus platyceros)

      Musbach, Jamie Lee; Tamone, Sherry; Kelley, Amanda; Eckert, Ginny (2021-12)
      Northern spot shrimp (Pandalus platyceros) support important commercial, subsistence, sport, and personal use fisheries in Alaska. This species is currently experiencing population declines in Southeast Alaska, mandating fishery closures in previously productive regions. Northern spot shrimp are harvested as adults and declining populations may be a result of limited recruitment into the fishery. Very little is known about the physiology of P. platyceros early life history stages and no known data exists on how early life history stages may be affected by environmental stressors such as ocean acidification (OA) and ocean warming (OW). OA is a result of increased anthropogenic carbon dioxide (CO₂) input into the ocean. Increased pCO₂ affects both the physical and chemical properties of the ocean, which, in turn, affects the marine biota. In addition to OA, ocean warming (OW) is another environmental stressor associated with ocean change. The Intergovernmental Panel on Climate Change (IPCC) predicts an oceanic pH decrease of 0.2-0.4 units and an increase in ocean temperatures up to 5°C by the year 2100. The goal of this thesis is to characterize potential individual and interactive effects of increased pCO₂ and increased temperature on the metabolic rate (MO₂), gene expression of heat shock protein 70 (Hsp70), and gene expression of carbonic anhydrase (CA) in juvenile P. platyceros. In order to assess the individual and interactive effects of these environmental stressors on juvenile P. platyceros physiology, I built a low-cost open hardware OA and OW system in the seawater lab at the University of Alaska Southeast. This pH-stat system, based on open-source Arduino platform, allowed manipulation of pH and temperature in line with the IPCC's future predicted ocean conditions. Juvenile P. platyceros are a model organism for this type of research due to predictions that early developmental stages, the requirement of calcification for growth, and cold-water marine organisms may be most susceptible to OA and OW stressors. Understanding how this ecologically and economically important species may be affected by environmental stressors can highlight the capacity of P. platyceros to withstand ocean change.
    • Effects of sea ice seasonal evolution and oil properties on crude oil upward migration through sea ice

      Oggier, Marc; Eicken, Hajo; Collins, Eric; Barnes, David L.; Pettit, Erin; Truffer, Martin (2020-12)
      Sea ice plays an essential role in polar ecosystems as a habitat for organisms at the base of the food web. Receding Arctic perennial sea ice, potential oil and gas reserves, and increasing industrial activities in the Arctic are likely to increase oil extraction and transport in the maritime Arctic. Despite a decrease in summer sea ice extent, Arctic waters remain covered with sea ice for much of the year, increasing the risk of an oil spill in and under Arctic sea ice. This dissertation addresses the need for a quantitative understanding of the timing of and constraints on oil mobilization through the full seasonal cycle as well as the resulting oil distribution within the ice cover. All of these factors have major implications for spill clean-up efforts and habitat damage assessments. In Chapter 1, I assemble sea ice physical properties derived from long-term observations to characterize sea ice seasonal development stages. In Chapter 2, guided by results from three sets of oil-in-ice tank experiments, I present a semi-empirical multistage oil migration model linked to sea ice seasonal stages. I also find that ice stratigraphy plays a major role in oil movement, with granular ice hindering oil movement. In Chapter 3, I quantify the microstructural differences between granular and columnar ice texture. While both pore spaces have similar pore and throat size distribution, the higher tortuosity of granular ice increases the distance oil and brine have to travel by up to 30% to cover the same vertical distance as in columnar ice. With a less connected pore space, granular ice permeability is estimated as one order of magnitude smaller than that of columnar ice during winter and at the onset of spring warming. Chapter 4 introduces a simple 1D vertical model with a small set of initial conditions to describe oil movement along a connected pore pathway, I constrain the oil flow by accounting for the lateral displacement of brine into the surrounding ice volume to improve prediction of the timing and distribution of oil-in-ice flow. Future coupling of this model to a model of ice growth and melt may help inform oil spill response and clean-up operations, and improve the understanding of oil migration in the context of natural resource damage assessments.
    • Efficient alternative food systems for earth and space

      Alvarado, Kyle A.; Denkenberger, David; Schiewer, Silke; Karlsson, Meriam (2020-12)
      Alternative foods are a source of human-edible calories derived from an unconventional source or process. This thesis includes two alternative foods: (i) crops grown under low-tech greenhouses in low sunlight environments and (ii) hydrogen-oxidizing bacteria (HOB) in space and Earth refuges, such as to repopulate the Earth. The purpose of alternative foods is to ensure food security for human survival. During a global catastrophic risk (GCR) scenario, such as nuclear winter or super volcanic eruption, the sun may be obscured, causing lack of crop production and therefore global food shortages. The purpose of this thesis was to improve the cost and energy use of producing food during a GCR by avoiding the need to use artificial light photosynthesis. As a solution, a low-tech greenhouse scaling method was designed that could feed the Earth as quickly and cost-effectively as possible during a GCR, such as nuclear winter. Using concepts derived for scaling HOB single cell protein (SCP), a cost analysis was conducted for space that relates to Earth refuges. The cost of HOB was compared to that of microalgae SCP and of dry prepackaged food in a closed-loop system. Low-tech greenhouses were designed with basic materials to continue the production of non-cold tolerant crops at low cost; cold tolerant crops would be able to grow outside of greenhouses where it does not freeze. Scaling of low-tech greenhouses, which would add a cost to food of $2.30 /kg dry, is currently one of the most effective alternative foods for Earth. HOB is an effective method of converting electrical energy into food, having an electricity to biomass energy conversion efficiency of 18% versus 4.0% for artificial light (vertical farming) of microalgae (other crops would be even less efficient).
    • Enhancing tumor antigen presentation with complement targeted liposomes

      Francian, Alexandra; Kullberg, Max; Kuhn, Thomas; Burkhead, Jason; Knall, Cindy (2021-08)
      Tumor-mediated immune evasion and suppression can be prohibitive to successful cancer treatment and recovery. A defining trait of cancer progression is when tumor cells develop the ability to evade detection by the immune system. Advanced tumors can suppress the presentation of antigens to effector immune cells by secreting regulatory cytokines and by downregulating the expression of major histocompatibility complex I (MHC I) receptors on the surface of tumor cells. Effective anti-tumor immunity requires the processing and persistent presentation of tumor antigens to effector cells. The cells responsible for this are antigen presenting cells (APCs), which initiate the immune response against cancer by engulfing and presenting tumor antigens to effector immune cells. APCs present tumor antigens, which provide specific targets for helper T cells and cytotoxic T lymphocytes, allowing the immune system to distinguish cancer cells from noncancerous cells. There are many different types of tumor antigens, and the increased effort to sequence reactive epitopes and establish a database makes tumor antigen immunotherapy a promising avenue for treatments and vaccines. Immunotherapies have been developed to restore the immune response against tumors without the toxic side effects of chemotherapeutic drugs. This research describes a promising cancer immunotherapy utilizing a liposome nanoparticle that binds to endogenous complement C3 proteins in serum and is internalized by APCs through the complement C3 receptor, resulting in direct delivery of encapsulated compounds. APCs were shown to internalize C3-bound liposomes containing ovalbumin (OVA), a model antigen, resulting in a significant increase in activated T cells that recognize OVA, reduced tumor growth in all mice (n=5), and complete elimination of both treated and distal tumors in two out of five mice (40%). Blood from treated mice had lower percentages of immunosuppressive cells, higher percentages of B cells, and increased anti-OVA IgG1. Collectively, treatment with OVA C3-liposomes is able to induce the activation of both cell-mediated and humoral immune responses. C3-liposomes encapsulating a melanoma tumor antigen, TRP-2, were able to reduce and eliminate established tumors in a melanoma tumor model in 6 out 7 mice (86%), with the addition of checkpoint blockade, anti-CTLA-4, improving the results (tumor reduction in all mice; n=3). C3-liposomes were also able to induce expression of costimulatory molecules and the production of proinflammatory cytokines and factors in targeted APCs. These results indicate that C3-liposome delivery of tumor antigens to APCs initiates a potent and systemic antitumor immune response.
    • Environmental drivers of fish communities and food webs in Gulf of Alaska estuaries

      Lundstrom, Nina; Beaudreau, Anne; Mueter, Franz; Konar, Brenda (2021-05)
      The coastal Gulf of Alaska (GOA) is experiencing rapid, climate-driven ecological change. Climate forecasts predict increased temperatures and more precipitation as rainfall, but these changes will not have uniform effects across nearshore ecosystems. Estuarine habitats will be dynamically affected by changes in neighboring watersheds as glaciers melt and recede. Because estuaries provide critical habitat for many fishes, including some that support fisheries, it is important to understand how changing estuarine conditions may impact nearshore fish communities. The overall goal of this thesis was to investigate how environmental conditions, fish communities, and food webs vary across estuaries fed by watersheds with varying glacial coverage (0-60%). We conducted monthly beach seining and measured environmental conditions from April to September 2019 at ten estuary sites in two regions of the GOA, Lynn Canal in southeastern Alaska and Kachemak Bay in southcentral Alaska. The goal of Chapter One was to characterize differences in estuarine fish communities along the glacial gradient, between regions, and throughout the sampling season. We then focused on two abundant species in Lynn Canal, starry flounder (Platichthys stellatus) and Pacific staghorn sculpin (Leptocottus armatus), and used multiple years of data (2014, 2016-2017, 2019) to determine environmental drivers of size structure for each species. Fish communities showed the greatest differences between regions and across months, and temperature and salinity were significant drivers of variation in species composition. Variation in mean length of Pacific staghorn sculpin was best explained by year and the interaction of site and month, whereas variation in mean length of starry flounder was best explained by temperature, salinity, and turbidity. The goal of Chapter Two was to provide foundational information on the diet of juvenile coho salmon (Oncorhynchus kisutch) during the estuarine life stage and characterize variation in diets between years and regions. Juvenile coho salmon have a diverse diet of terrestrial and marine invertebrates and fishes, and they exhibited a shift to piscivory during this transitional period in nearshore habitats. Site differences accounted for most of the variability in diet, while temperature and salinity only accounted for a total of 12% of the variability in diet. Overall, we found that fish communities in GOA estuaries vary with environmental and habitat conditions, but that the glacial to non-glacial watershed gradient was less important in explaining variation in fish community structure than regional and interannual differences.
    • Environmental impacts on reproductive responses of Pacific walruses (Odobenus rosmarus divergens) and subsistence users of St. Lawrence Island

      Larsen Tempel, Jenell T.; Atkinson, Shannon; Kruse, Gordon H.; Fugate, Corey; Pyenson, Nick (2020-08)
      An interdisciplinary approach is used in understanding change and resiliency in St. Lawrence Island (SLI) resources and resource users throughout this dissertation. Historically SLI inhabitants have relied on the Pacific walrus (Odobenus rosmarus divergens) for their survival and this resource is still highly valued for cultural and dietary purposes. The responses of Pacific walruses and SLI subsistence users to environmental change was analyzed. In walruses, reproductive capacity was analyzed using an anatomical approach as well as reproductive plasticity which was determined using a physiological approach to characterize their estrus cycle. A suite of anatomical measurements were developed to characterize reproductive capacity of walruses by analyzing ovaries from three distinct time frames during a 35-year period. Reproductive capacity was reduced during time frames when carrying capacity (K) was reached and when large environmental changes occurred in the Bering Sea, including years of very low sea ice extent. Reproductive capacity was high in times when K was lower and harvest levels were greater. Our results explained how perturbations in K and environmental changes may have influenced reproductive capacity of the population in the past. Endocrine techniques were used in ovarian tissues to determine if progesterone and total estrogens are useful indicators of female reproductive status in walruses harvested during the spring hunt. Progesterone and total estrogen concentrations were greater in the reproductive tissues of unbred and pregnant females than postpartum females, however neither hormone could distinguish between pregnant and unbred animals. These results provide the first physiological evidence for pseudopregnancy in this species, rather than a postpartum estrus. Lastly, discussions were held with SLI community members to determine changes in key subsistence resources and community resiliency with regard to food security. Walruses ranked highest among key resources. Stakeholders reported limited access and increased effort to hunt walruses, changes in crab abundance, and increases in commercially exploitable fish stocks. Changes were attributed to loss of sea ice, "bad" weather, and climate change. In order for SLI communities to continue their subsistence-based way of life, inhabitants may need to expand their diet to include less-preferred food items in place of harvested ice-associated species. In conclusion, loss of sea ice and rapid environmental changes in the Bering Sea have the potential to greatly impact walrus reproduction and the marine subsistence way of life that is practiced by SLI stakeholders.
    • Environmental influence on size frequency distributions of the Pacific blue mussel (Mytilus trossulus) in two glacially inlfuenced estuaries

      Dowling, Amy; Konar, Brenda; Iken, Katrin; Horstmann, Lara (2021-12)
      The Pacific blue mussel (Mytilus trossulus) is a foundation species in high-latitude intertidal and estuarine systems that can create complex habitats, provide sediment stability, serve as food for top predators, and act as connectors between the water column and the benthos. M. trossulus also makes an ideal model species to assess biological responses to environmental variability, as its size frequency distributions can be influenced by the environment in which it lives. Size frequency distributions can provide valuable information about ecological systems that are experiencing environmental change (e.g., increased global temperatures). M. trossulus populations in high latitude estuaries receive freshwater runoff from snow and glacial-fed rivers or can be under oceanic influence. These hydrographic conditions work together with local static environmental variables, such as substrate, fetch (potential for wave action), beach slope, distance to freshwater, and percent glaciation (glacial discharge) to influence recruitment, growth, and mortality of mussels. In 2019 and 2020, M. trossulus was collected from 15 intertidal sites in two Gulf of Alaska ecoregions with varying hydrographic conditions to determine if and how mussel size frequencies change over spatial and hydrographic scales, and whether any static environmental characteristics correlated with this variability. This study demonstrated that M. trossulus size frequencies were most comparable at sites with similar hydrographic conditions and grouped according to the ecoregion and year of collection. M. trossulus recruits (0-2 mm) were mostly seen at sites with higher fetch, while large mussels (> 20 mm) were mostly seen at more protected sites (low fetch) and in areas with more freshwater influence. Hydrographic conditions explained approximately 43% of the variation in M. trossulus size frequencies for both years, which was three times more than the variation explained by ecoregion and four times more than collection year. Fetch and distance to a freshwater source explained most of the variation in mussel size frequencies for both years, while substrate type was also important in 2019, and percent glaciation in 2020. M. trossulus recruitment was significantly different between 2019 and 2020, possibly resulting in the different static variable correlates between the two years. This study suggests that hydrographic conditions play an important role in structuring M. trossulus size frequencies, and that these differences also depended on environmental conditions.
    • An evaluation of GPR techniques for analyzing the safety of Interior Alaskan ice roads under varying river ice and environmental conditions

      Richards, Elizabeth M.; Stuefer, Svetlana; Maio, Chris; Belz, Nathan; Daanen, Ronald (2021-05)
      Ice roads and bridges are necessary routes to transport heavy equipment, supplies and food in the winter months to and from isolated cold region communities off the road system. Ice roads allow for community members to avoid the high costs of air shipments and obtain equipment and vehicles that would otherwise not be available. These ice roads traverse frozen bodies of water (e.g., rivers, estuaries, and lakes), and require extreme safety when driving over. To achieve this, calculations are frequently completed to determine the maximum acceptable loading on the ice cover. River ice tends to have increased safety concerns and uncertainty for travel that stem from warmer air temperatures and other factors such as precipitation, snow drifting, and ice cover forming differently each year. The necessity of obtaining time intensive ice thickness measurements by hand puts the responsible personnel at considerable risk of injury or fatality. Ground penetrating radar (GPR), which has gained much popularity in the last few decades, is a quicker and more effective non-invasive method for measuring ice thickness and other properties. The GPR system was tested for its accuracy in measuring ice thickness on common transportation routes on the Yukon River and the Tanana River. Identification of varying ice type layers in river ice cover using GPR was also attempted. While layers could not be identified using the 450 MHz and 750 MHz central frequency antennas, an accuracy analysis of GPR ice thickness measurements under various environmental conditions was completed. This analysis contributes to a comprehensive understanding of the safety of ice roads for community members in remote northern villages and provides the basis for further research on identifying layers in river ice cover.
    • Experimental investigation of polymer induced fouling of heater tubes in the first-ever polymer flood pilot on Alaska North Slope

      Dhaliwal, Anshul; Dandekar, Abhijit; Zhang, Yin; Goering, Douglas J. (2021-08)
      Mineral fouling in heat exchangers has been extensively investigated by researchers in recent times. The oil and gas industry has a long history of fouling issues in production systems as a result of produced fluids treatment. Due to decline in production rates in oilfields new technologies are being developed and field tested in pilots. Polymer flooding is one such technology that involves addition of polymers to injection fluids to enhance oil production. A polymer flood pilot has been set up in the Schrader Bluff viscous oil reservoir at Milne Point field on the Alaska North Slope (ANS). The results from the pilot are encouraging, however a major concern of the operator is the influence of polymer on the production system after breakthrough, especially the fouling in heat exchangers. This study investigates the propensity of polymer fouling on the heater tubes as a function of different variables, with the ultimate goal of determining safe and efficient operating conditions. This work applies a multi-experimental approach to study the severity of polymer-induced fouling in both dynamic and static states of produced fluids as well as studying the stability of polymer solutions at different temperatures. A unique experimental setup was designed and developed in-house to simulate the fouling process on the heating tube. The influence of heating tube skin temperature, tube material, and polymer concentration on fouling tendency was investigated. Each test was run five times with the same tube, and in each run, the freshly prepared synthetic brine and polymer solution was heated from 77°F to 122°F to mimic field-operating conditions. The heating time and fouling amount were recorded for each run. Dynamic Scale Loop (DSL) tests were conducted to study fouling due to polymer at different temperatures (165°F to 350°F) in a dynamic state of fluid flow where the fluids mimic the residence time of fluids in the heat exchanger on the field pilot. Cloud point measurement has also been conducted to find the critical temperature at which the polymer in solution becomes unstable and precipitates out. The morphology and composition of the deposit samples were analyzed by environmental scanning electron microscopy (ESEM) and X-ray diffraction (XRD), respectively. It was found that the presence of polymer in produced fluids would aggravate the fouling issues on both carbon steel and stainless-steel surfaces at all tested skin temperatures. Only higher skin temperatures of 250°F and 350°F could cause polymer-induced fouling issues on the copper tube surface, and the fouling tendency increased with polymer concentration. At the lower skin temperatures of 165°F, no polymer-induced fouling was identified on the copper tube. A critical temperature that is related to the cloud point of the polymer solution was believed to exist, below which polymer-induced fouling would not occur, and only mineral scale was deposited but above which the polymer would aggravate the fouling issue. The cloud point of the tested polymer solution was determined to be between 220°F and 230°F. In the DSL tests it was found that at higher skin temperatures of 250°F and 350°F tube blocking was observed in the DSL tests whereas the tests at 165°F and 200°F did not show any tube blocking in the same time period. These experiments also manifested the influence of cloud point of the solution as deposit rate increased significantly in both carbon steel and stainless-steel tubes when the skin temperature was higher than the solution cloud point. The results of this study have provided guidance to the operator for the field-operations.
    • Experimental investigation of the role of different clays in low salinity waterflooding

      Ivuawuogu, Henry; Zhang, Yin; Dandekar, Abhijit; Khataniar, Santanu; Awoleke, Obadare (2020-08)
      Various studies have demonstrated that Low Salinity Water Flooding (LSWF) can enhance oil recovery effectively, and its typical recovery mechanisms have been recognized. However, there is still a significant debate on the functions of clay during LSWF. This study investigates the impact of different clays, including montmorillonite, illite, and kaolinite, on the performance of LSWF. The zeta potentials of sand, montmorillonite, illite, and kaolinite in the presence of high salinity water (HSW) and low salinity water (LSW) were first examined. Then, the swelling factors of the three clay minerals in the HSW and LSW were measured in succession to determine their swelling characteristics. Subsequently, coreflooding experiments were conducted using one clay-free sand pack column and five sand pack columns respectively containing 10 wt% of montmorillonite, 10 wt% of illite, 10 wt% of kaolinite, compound clays (5 wt% of montmorillonite + 2.5 wt% of illite + 2.5 wt% of kaolinite), and 5 wt% of montmorillonite and the cumulative oil production and pressure drops were recorded. A produced crude oil sample with the American Petroleum Institute (API) gravity of 34° and viscosity of 14 cP (60°F) was used in the experiments. The total dissolved solids (TDS) of the HSW and LSW are 27,501 mg/L, and 2,485 mg/L respectively. It has been found that LSW could generate more negative zeta potential values for sand, montmorillonite, illite, and kaolinite, which made them more water-wet and thus favor oil recovery. Montmorillonite obviously swelled in HSW, and it could further swell significantly by contacting LSW. Although illite showed some swelling in HSW, LSW could not further expand it. Kaolinite did not swell in both HSW and LSW. The results from six coreflooding experiments showed that after high salinity waterflooding, the subsequent LSWF could generally further improve the oil recovery. The sand pack columns containing montmorillonite showed higher incremental oil recovery during LSWF (17.42% from sand pack column with 10 wt% of montmorillonite, 10.27% from sand pack column with compound clay, and 8.90% from sand pack column with 5 wt% of montmorillonite). Also, LSWF could improve oil recovery for the clay-free sand pack column, the sand pack column with kaolinite, and the sand pack column with illite by 0.73%, 0.83%, and 1.03%, respectively. Therefore, clay minerals would play an important role in determining oil recovery performance in LSWF, and the more swelling there is in clay in LSW, the more favorable it is in LSWF. This study proved that both clay swelling and wettability alteration could attribute to the improved oil recovery by LSWF.