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  Differential use of willow species by moose in Alaska

  Machida, Steven (1979)

  Patterns of differential winter utilization of willow by moose in Interior Alaska and the Kenai Peninsula were studied during 1977 and 1978. Knowledge of such patterns is important to the wildlife manager who must evaluate the relative importance of different habitat types for moose. The study areas were composed of sites dominated by mature and seral habitat types.
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  Iceberg calving dynamics of Jakobshavn Isbræ, Greenland

  Amundson, Jason Michael; Truffer, Martin; Motyka, Roman; Bueler, Ed; Hock, Regine; Pettit, Erin (2010-05)

  Jakobshavn Isbræ, a fast-flowing outlet glacier in West Greenland, began a rapid retreat in the late 1990's. The glacier has since retreated over 15 km, thinned by tens of meters, and doubled its discharge into the ocean. The glacier's retreat and associated dynamic adjustment are driven by poorly-understood processes occurring at the glacier-ocean interface. These processes were investigated by synthesizing a suite of field data collected in 2007 2008, including timelapse imagery, seismic and audio recordings, iceberg and glacier motion surveys, and ocean wave measurements, with simple theoretical considerations. Observations indicate that the glacier's mass loss from calving occurs primarily in summer and is dominated by the semi-weekly calving of full-glacier-thickness icebergs, which can only occur when the terminus is at or near flotation. The calving icebergs produce long-lasting and far reaching ocean waves and seismic signals, including "glacial earthquakes". Due to changes in the glacier stress field associated with calving, the lower glacier instantaneously accelerates by ~3% but does not episodically slip, thus contradicting the originally proposed glacial earthquake mechanism. We furthermore showed that the predominance of calving during summer can be attributed to variations in the strength of the proglacial ice melange (dense pack of sea ice and icebergs). Sea ice growth in winter stiffens the melange and prevents calving; each summer the mélange weakens and calving resumes. Previously proposed calving models are unable to explain the terminus dynamics of Jakobshavn Isbræ (and many other calving glaciers). Using our field observations as a basis, we developed a general framework for iceberg calving models that can be applied to any calving margin. The framework is based on mass continuity, the assumption that calving rate and terminus velocity are not independent, and the simple idea that terminus thickness following a calving event is larger than terminus thickness at the event onset. Although the calving framework does not constitute a complete calving model, it provides a guide for future attempts to define a universal calving law.
• The avialan fauna of the late Cretaceous Prince Creek Formation, Alaska

  Wilson, Lauren N.; Druckenmiller, Patrick; Fowell, Sarah; Ksepka, Daniel (2024-05)

  Modern polar regions are critical breeding grounds for over 250 species of birds. Some migrate to high latitudes for access to seasonally abundant resources during reproductive periods, whereas others are year-round residents. Despite the major role these birds play in polar ecosystems, we know very little of the origins of the utilization of polar ecosystems for nesting due to the rarity of avialan fossils from high latitudes. The avialan fossil record spans 150 million years, yet evidence for high-latitude bird reproduction extends only to the Eocene La Meseta Formation of Antarctica (56-33.6 Ma). Here, we report a remarkable polar avifauna from the northernmost fossil-bearing Late Cretaceous ecosystem in the world, the Prince Creek Formation of northern Alaska (PCF). The PCF was deposited at 80-85°N paleolatitude, where continuous summer daylight would have lasted nearly six months. It preserves an ancient polar ecosystem including avian and non-avian dinosaurs, mammals, and fishes. The PCF avialan material was found as part of a decade-long microfossil analysis of channel lag deposits. Numerous skeletal elements, representing almost the entire avialan skeleton, constitute one of the most comprehensive and well-preserved Late Cretaceous avifaunas in the world. These fossils share morphological affinities with hesperornithines, ichthyornithines, and crown birds. Further, abundant perinatal fossils represent the youngest-known growth stages of Mesozoic euornithines. This is the oldest direct evidence for polar bird reproduction and demonstrates that multi ---taxic bird nesting has occurred in the High Arctic for at least 73 million years--nearly half the tenure for birds on Earth. Likewise, these fossils demonstrate that this behavior originated in the Mesozoic ancestors of modern birds, millions of years before the radiation of crown group birds following the end-Cretaceous mass extinction.
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  Effects of hunting pressure on the spatial dynamics of a subarctic caribou herd

  Wells, Jeffrey; Crimmins, Shawn; Brinkman, Todd; Bentzen, Torsten (2024-05)

  Indirect effects of hunting can have important ecological and hunt management implications, and little has been done to quantify these indirect effects on caribou (Rangifer tarandus). To assess effects of hunting pressure on caribou spatial dynamics, we used GPS locations that spanned fall and winter 2010-2022 from the semi-migratory Fortymile caribou herd in interior Alaska. We analyzed these locations using integrated step selection analysis to evaluate step lengths (i.e., movement rates) and selection of distance to roads and trails, and forest cover across 3 hunting pressure levels (none, low, and high) as well as road crossings during hunting compared to non-hunting periods. We found that the caribou response to hunting pressure varied by season and, within the fall season, by hunting pressure level. Relative to no hunting pressure, caribou in fall showed a very strong avoidance of roads at high hunting pressure and a lower avoidance at low hunting pressure. Similarly, caribou in fall showed an avoidance of trails at high hunting pressure although, unlike roads, the avoidance continued at low hunting pressure. Conversely, relative to no hunting pressure, caribou did not change their selection of forest cover in either season nor did they alter their selection of roads or trails in winter. Furthermore, in both seasons, changes in step lengths in response to hunting pressure were less than we expected. Last, caribou avoided road crossings more during hunting compared to non-hunting periods in both seasons. Overall, caribou response to hunting pressure could have implications for caribou availability to hunters, especially during the fall season, as well as caribou distribution in relation to roads across both seasons. Hunt managers and public stakeholders could use our results to inform how changes to caribou harvest management might indirectly impact caribou movements and hunter opportunity.
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  Early life biology and ecology of king and tanner crabs in the Bering and Chukchi seas

  Weems, Jared; Eckert, Ginny; Mueter, Franz; Kimmel, David; Long, W. Christopher (2024-05)

  Pelagic larvae and early benthic juveniles are believed to be the most vulnerable life stages for crabs. Where and when young crab occur and their response to environmental conditions is poorly understood. I present two case studies that demonstrate the importance of monitoring crab early life stages of economically and ecologically important species in the Bering and Chukchi Seas. First, collapsed fisheries and poor juvenile recruitment are recurring issues for many Alaska king crab stocks. Among the most notable examples, Pribilof Islands blue king crab is a federally overfished stock that has failed to rebuild after decades of conservation. Comparison of field assessments from modern and historical periods suggests a current bottleneck in larval supply, severely limiting blue king crab recruitment. Supplementary assessments showed available nursery habitats and fish predation pressure do not appear to be limiting for juvenile king crabs. Blue king crab are unlikely to recover by natural means, therefore juvenile enhancement may be an appropriate tool for possible restoration. Second, larval crab dispersal during the pelagic life phase is relatively unknown across the Pacific Arctic. A multiyear study of larval crab abundance and distribution during late summer months, and their association with environmental covariates, was completed for the north Bering and Chukchi Seas. Larval community structure varied strongly across regions from south to north and many species and stages had specific associations with coastal or offshore water masses. Snow crab larvae were relatively abundant and ubiquitous across the study region and appear to originate from both Pacific and Arctic spawning stocks. Blue king crab larvae were relatively rare in the Chukchi Sea and likely dispersed away from north Bering Sea natal areas. Larvae likely experience increased growth rates and northward dispersal in warm years, which could impact delivery to and survival of settling crabs in nursery habitats. Across analyses, these results improve our understanding of early life dispersal, settlement processes, and possible recruitment bottlenecks for Arctic crab stocks.
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  Synthesis and stereoselective reduction of α-fluoro-β-ketoesters by ketoreductases

  Vanagel, Matthew G.; Green, Tom; Rasley, Brian; Kuhn, Thomas (2024-05)

  Using commercially available ketoreductase (KRED) enzymes, α-fluoro-β-hydroxy esters were stereoselectively synthesized from racemic α-fluoro-β-keto esters through dynamic reductive kinetic resolution (DYRKR). The α-fluoro-β-keto esters were synthesized via Reformatsky reactions between an aromatic aldehyde and ethyl bromofluoroacetate and subsequent oxidation with Dess Martin Periodinane (DMP). Two enzymes were selected for their ability to yield either syn or anti diastereomers. Three aromatic substrates were reduced in high diastereomeric and enantiomeric excess and good yields. The KRED products were derivatized with (R)- and (S)-α-methoxy-α-trifluoromethylphenylacetic acid (MTPA) and analyzed via ¹⁹F NMR spectroscopy to determine their absolute stereochemistry via Mosher ester analysis. For the three substrates, KRED 110 yielded the anti 2S,3S isomer. KRED 130 predominantly yielded the syn 2S,3R isomer but with less specificity. The use of these commercially available KRED enzymes provides access to enantio- and diastereomerically pure α-fluoro-β-hydroxy esters from readily accessible racemic substrates. Optically pure α-fluoro-β-hydroxy esters may serve as useful intermediates in the synthesis of medicinally relevant compounds such as fluorinated amino acids or fluorinated sphingolipid derivatives.
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  Heat transfer techniques in large-scale hydrogen storage using metal hydride materials

  Thomas, Seth A.; Kim, Sunwoo; Peterson, Rorik; Huang, Daisy (2024-05)

  One of the methods being investigated for storing hydrogen is the use of metal hydride materials. Metal hydrides are able to absorb and release hydrogen, giving them a wide range of potential applications for hydrogen storage. These materials are generally considered to be safe, stable, reusable, and are able to store and release hydrogen at lower pressures and near ambient temperatures. Despite these benefits, there are still existing limitations that hinder their widespread applicability. One of the main issues presented is the necessity for effective heat removal during the absorption process. When hydrogen is being absorbed by the metal hydride material, a large amount of heat is generated, which must be efficiently removed from the metal hydride reactor in order to achieve reasonable charging times. The first section of this thesis investigates the existing methods that have been proposed and studied for heat removal during this process. Some of these methods include the use of embedded cooling tubes, external water jackets, phase change materials, and high thermal conductivity additives. A method to characterize each type of reactor is also introduced in this section, based on certain parameters, which include characteristic length, mass of metal hydride material stored, mass of hydrogen stored, and cooling time. The following section simulates cooling times for two proposed large-scale shell-and-tube metal hydride reactors. The first reactor tested has embedded cooling tubes and metal hydride powder packed into the shell side. It was found that the absorption process could be completed in 1500-2000 s, depending on the tube bundle configuration. Additionally, a large hydrogen supply pressure (30 bar) was needed for reasonable reaction times to be achieved. The other reactor packed embedded tubes with annular metal hydride pellets, with the cooling fluid passing through the shell side of the reactor. This type of reactor showed a promising cooling time of 430 s with a hydrogen supply pressure of 10 bar. This type of reactor was more limited though by the percent volume that could be occupied by metal hydride material.
• Climate influences emerge within two decades of observations for pelagic tunicates and pelagic snails in the northern Gulf of Alaska

  Stidham, Emily; Hopcroft, Russell; Hennon, Gwenn; Danielson, Seth (2024-05)

  Mucus-net feeders are under-appreciated organisms that can have large impacts on how organic matter moves through food webs. In the Northern Gulf of Alaska and Prince William Sound they are represented primarily by pelagic tunicates (larvaceans, doliolids, salps) and pelagic snails (pteropods). Over a 20-year time-series (2001-2021) there was strong seasonality of larvacean abundance and species composition. Spring was dominated by Oikopleura labradoriensis and Fritillaria borealis, with higher diversity during autumn, due largely to the periodic presence of warm-water species. There was a distinct cross-shelf gradient with Oikopleura dioica, spreading across the lower salinity shelf during the autumn, and Fritillaria species becoming more prominent at offshore stations. Up to 45% of individual species and 19% to 28% of the tunicate community variation could be explained by physical variables (Temperature, Salinity, Chlorophyll α) and climate indices (ENSO, PDO, NPGO) during the spring and autumn, respectively. There were pronounced shifts in species composition and abundance during marine heatwaves. Limacina helicina showed a negative relationship to climate indices, with strongest correlation to the North Pacific Gyre Oscillation during spring. These long-term species-level records in subarctic waters provide improved understanding of how the mucus-net feeding community may continue to shift in a changing ocean climate.
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  Sediment characteristics and economic potential of large methane seeps in Esieh Lake, NW

  Sharp, Janelle Marie Anasuk; Anthony, Katey Walter; Meyer, Franz; Miller, Lance (2024-05)

  My thesis evaluates lake sediment characteristics and how they have been affected as large geologic methane (CH₄) seeps formed in Esieh Lake (informal name), a lake in Northwest Alaska. I provide extensive background of the lake, including a synthesis of studies and reports that characterize the geology around this lake which, to date, contains the largest known CH₄ seeps in the Arctic. In addition to providing background information on Esieh Lake and characterizing the lake's sediments, I evaluate the economic potential for the CH₄ seeps and compare flux values to natural gas projects which were previously completed in Alaska and Canada. The evidence suggests the possibility that CH₄ seeps initiated in Esieh Lake sometime within the last century via an explosive event that formed large pockmarks in the lake bottom. Rapid expansion of the seep field occurred between 1952 and 1972. Seepage continued after the blowout event and is still present today, albeit at a more quiescent stage. An economic evaluation of the seep as an energy source found that the capital cost for infrastructure to transport gas to a nearby community resulted in high energy costs, higher than the current cost of electricity in Noatak from imported diesel. However, if infrastructure capital costs were not a factor, then the cost of electricity for Noatak using Esieh Lake seepage as natural gas, would be much lower that current electricity costs. Through existing technologies, Esieh Lake is not economically viable as a resource but as technology progresses, developing a very small-scale gas resource may become a viable option.
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  Deep learning detection and quantification of volcanic thermal signals in infrared satellite data

  Saunders-Shultz, Pablo; Lopez, Taryn; Dietterich, Hannah; Girona, Társilo; Grapenthin, Ronni (2024-05)

  Volcanic eruptions pose hazards to human lives and livelihoods (Loughlin et al., 2015). To mitigate these hazards, volcano monitoring groups aim to detect signs of unrest and eruption as early as possible. Prior to eruption volcanoes may show various signals of unrest, including: increased surface temperatures, surface deformation, increased seismicity, increased degassing, and more. Here we focus on one approach to monitor volcanic unrest: detecting high-temperature localized volcanic heat emissions, otherwise known as hotspots. The presence of hotspots can indicate subsurface and surface volcanic processes that precede, or coincide with, eruptions. Space-borne infrared sensors can identify hotspots in near-real-time; however, automatic hotspot detection systems are needed to efficiently analyze the large quantities of data produced. While hotspots have been automatically detected for over 20 years with simple thresholding algorithms, new computer vision technologies, such as convolutional neural networks (CNNs), enable improved detection capabilities. Here we introduce HotLINK: the Hotspot Learning and Identification Network, a CNN-based model to detect volcanic hotspots in VIIRS (Visible Infrared Imaging Radiometer Suite) imagery. We find that HotLINK achieves an accuracy of 96% when evaluated on a validation dataset of ~1,700 unseen images from Mount Veniaminof and Mount Cleveland volcanoes, Alaska, and 95% when evaluated on a test dataset of ~3,000 images from six additional Alaska volcanoes (Augustine Volcano, Bogoslof Island, Okmok Caldera, Pavlof Volcano, Redoubt Volcano, Shishaldin Volcano). Additional testing on ~700 labeled MODIS images demonstrates that our model is applicable to this sensor's data as well, achieving an accuracy of 98%. We apply HotLINK to 10 years of VIIRS data and 22 years of MODIS data for the eight aforementioned Alaska volcanoes. From these time series we find that HotLINK accurately characterizes background and eruptive periods, similar to a threshold-based method, MIROVA, but also detects more subtle warming signals, potentially related to volcanic unrest. In particular, analysis of the Mount Veniaminof record demonstrates that HotLINK is able to detect subtle hotspot signals that are coincident with elevated seismicity, potentially indicative of surface heating due to shallow magma intrusion and/or degassing. We identify three advantages to our model over its predecessors: (1) the ability to detect more subtle volcanic hotspots and produce fewer false positives, especially in daytime imagery; (2) the incorporation of probabilistic predictions for each detection that provide a measure of detection confidence; and (3) its transferability to multiple sensors and multiple volcanoes without the need for threshold tuning, suggesting the potential for global application. HotLINK is able to identify eruptions and potentially precursory warming signals in infrared satellite data, making it a valuable tool for monitoring volcanoes and tracking their heat released over time.
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  Synergistic effects of climate and invasions: a case study of juvenile Pacific salmon and their introduced freshwater predator (Esox lucius) in a changing Alaska river

  Rich, Benjamin; Westley, Peter; Sepulveda, Adam; Falke, Jeff; Rinella, Daniel (2024-05)

  Climate change and invasive species are major individual drivers of declines in freshwater productivity and diversity, yet the potential for these factors to interact is poorly understood. I explored the synergistic effects of climate change and invasion to better understand observed changes in a freshwater community comprised of socially valuable salmonid fishes. I modeled daily predation and annual consumption of juvenile salmon by an introduced apex predator, Northern Pike (Esox lucius), as a function of time, streamflow, water temperature, and Northern Pike demography in a rapidly warming system in Southcentral Alaska. I hypothesized that Northern Pike predation would shift from juvenile salmon to alternative prey as a function of progressed invasion and that salmon predation would peak during species-specific out migrations. I also hypothesized that predation on juvenile salmon would be positively correlated with streamflow because high water would cause juvenile salmon to seek refuge in off-channel habitats instigating interaction with Northern Pike. Daily predation and annual consumption of Northern Pike in this system have shifted away from salmon-dominated to dominated by resident fishes over the past decade (2011 to 2022). Streamflow was positively correlated with daily predation on juvenile Chinook Salmon and total Oncorhynchus species in diets. Between 2011-2012 and 2021-2022 the population of Northern Pike shifted to younger individuals with increased growth. Estimates revealed that annual consumption of Chinook Salmon and Coho Salmon by Northern Pike decreased between time periods. Bioenergetic simulations revealed increases of 6 to 12.5% in total per capita consumption of prey by Northern Pike under end of century scenarios. These findings collectively suggest that Northern Pike have switched to alternative fish prey as salmon declined. Seasonal high streamflows and increased water temperature consistent with observed and predicted climate change in Southcentral Alaska appear to increase predation rates on juvenile Chinook Salmon by Northern Pike, while patterns in predation for juvenile Coho Salmon are more uncertain. Predicted future temperatures may increase total consumption of Northern Pike enough to appreciably increase mortality of salmon exacerbating changes in species composition and community structure and further jeopardizing struggling salmon runs. These findings suggest that invasive predators may also become more impactful in other systems undergoing rapid climate change.
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  An intertaxon dissimilarity for level-1 phylogenetic networks from rooted triples

  Palmer, Noah; Allman, Elizabeth; Rhodes, John; Faudree, Jill (2024-05)

  An important problem in evolutionary biology is how to infer the evolutionary history of a set of taxa in the presence of hybridization. In this work, we present an important first step in the establishment of an algorithm for the inference of a level-1 species network under the Network Multispecies Coalescent Model using rooted triples. In particular, we define a new intertaxon dissimilarity, dRT , which can be directly computed from the topology of the rooted triples displayed on a network, and might be estimated from data. In our main result we prove that this dissimilarity is equivalent to an intertaxon splits dissimilarity, dλRT , which can be used to reconstruct a level-1 species network using the NeighborNet and Circular Network Algorithms.
• CO₂ transport at a supercritical state: Nikiski, Alaska pipeline study and cost analysis

  Ophoff, Mike; Chen, Cheng-fu; Zhang, Yin; Paskvan, Frank; Nguele, Ronald (2024-05)

  CO₂ in the supercritical state is suitable for long-distance transportation because of the denser flowing fluid, almost the same density as liquid CO₂ but has lower viscosity and surface tension. Albeit this well-known principle, it is nontrivial to implement a scheme for single-phase, supercritical CO₂ transportation on a given pipeline. As the pressure and temperature are the major state variables governing the state of the transported CO₂, the state of the fluid is determined by a complex interaction among the key parameters: the inner diameter, insulation material, inlet pressure and temperature, and the boundary conditions (including the ambient temperature and inner pipeline wall roughness) of the pipeline; the mass flow rate and distance of transportation. This paper applies the PIPESIM software, with MATLAB for auxiliary calculations, to illustrate a parametric study of the supercritical CO₂ transportation over a 10.618-mile (17,080 m) long model pipeline connecting from Nikiski to the Osprey platform in the Redoubt oil field in Cook Inlet, Alaska, USA. This study aims to understand the limitations and optimize transportation efficiency while maintaining the supercritical state of transported CO₂ throughout the pipeline. With the geographic location, elevation profile of the pipeline, and the ambient conditions considered in the simulations, we calculate the pressure and temperature profiles, erosion kinetics, and the fluid state in the combinatorial set of various diameters, inlet pressures, and temperatures of the pipeline and the mass flow rates of the transported fluid. The major findings are that a larger pressure loss will be expected in better-insulated pipelines because of the warmer transported CO₂ that flows faster. Turbulent flows will be more likely to occur in transportation through pipelines of smaller diameters and will impact on possible change from the supercritical state to the two-phase state. The parametric modeling results offer a scenario-driven approach to determine the optimal range of mass flow rates, pipeline inner diameters, and inlet pressures. A cost analysis was conducted for the construction and operating expenditures of pipelines over a 20-year lifetime span. We highlight the trade-offs between maintaining supercritical conditions, minimizing heat loss, and increasing financial viability for efficient transportation.
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  Implementation of community-based natural resource management at Hustai National Park, Mongolia

  Nyamdavaa, Tsermaa; McBeath, Jennifer; Duffy, John; Drew, Elaine; Carroll, Jennifer; Finstad, Greg (2024-05)

  Community-based natural resource management (CBNRM) combines scientific knowledge with community involvement to manage a variety of common pool resources (CPR) in a sustainable manner. In Mongolia, CBNRM has been implemented to manage rangelands in response to severe winters and rangeland degradation. In particular, Hustai National Park (HNP) has faced challenges due to the increased number of livestock which has led to exceeding the carrying capacity of the Buffer Zone rangelands despite efforts to implement CBNRM since 2004. The overarching question guiding the research is: How have CBNRM principles been implemented at HNP? In order to answer the research question, the research design employed the case study method, with HNP as the case. A convergent parallel design was utilized. Data collection methods consisted of survey questionnaires, semi-structured interviews, and archival document reviews. Survey questionnaires and semi-structured interviews were conducted to obtain data from the stakeholder groups, which consisted of HNP officials, local government officials, and herders. The research revealed that CBNRM principles have not been fully implemented for protecting the Buffer Zone rangelands. More specifically, most CBNRM principles have not been met; the use of a top-down approach has been employed; and there are conflicts between CBNRM principles and interpretations of the Mongolian Constitution. Furthermore, the research indicated that CBNRM principles have not protected the Buffer Zone rangelands, as evidence indicates the state of the Buffer Zone rangelands has moved to a degraded state between 2010 and 2020, primarily due to overgrazing. Also, the study suggests that there have been some improvements; however, CBNRM methods have generally failed to improve the livelihood of the majority of herders. Therefore, the research emphasizes the need for a more effective implementation of CBNRM principles at HNP.
• Statistical analysis of stream sediments in the Mt. Freegold area of the Dawson Range, Central Yukon Territory, Canada

  Mueller, Heiko; Meyer, Franz; Newberry, Rainer; Nadin, Elisabeth (2024-05)

  The study uses data and samples from a 2009 and 2012 stream sediment sampling program, conducted in part by the author. With the aim to identify gold-bearing prospects, a data set of 417 samples was digested with aqua regia and analyzed using inductively coupled plasma mass spectrometry (ICP-MS). I had leftover material from the original samples reanalyzed by ICP-MS after 4 acid (nitric + hydrochloric + hydrofluoric + perchloric) digestion. I compared the compositional data for the two sample sets (308 samples, 45 elements). Accuracy and precision (reproducibility) for all elements of the aqua regia sample set is noticeable lower than that of the 4 acid digestion set. Accuracy is computed by the relative error that compares the assay of the standard sample to the known concentration of the standard. Precision is an estimate of the reproducibility of the sampling and analytical system. Precision is calculated by fractional uncertainty. Field duplicates are produced by splitting samples in two. Fractional uncertainty is calculated for each pair of original sample and field duplicate. Gold shows the lowest precision of all elements for both data sets, most likely due to the nugget effect. Using a paired sample T-Test I concluded that the mean concentrations of 42 elements are different for aqua regia versus 4 acid digestions. Only for three elements (sulphur, bismuth and copper) were non-distinguishable average element concentrations found for both digestion methods. A negative t-statistic (based on aqua regia vs. 4 acid digestion-based compositions) implies higher elemental recovery by 4 acid digestion. The aqua regia data set record only a portion (presented in brackets) of the values for 4 acid digestions for these elements: Na (1%), Hf (2%), Zr (3%), K (4%), Nb (5%), Sr (7%), Al (11%), Ti (12%), Rb (14%), Ba (16%) and Ca (19%). The digestion method determines the degree of element recovery from the solids (i.e., dissolution into solution) and consequently 'trustworthiness' of a given element's concentrations. This, in turn, dictates the element's usefulness for identifying prospective targets. The digestion method sets the frame for the spectrum of possible discoveries. As demonstrated 4 acid digestion has a high trustworthiness of a given element's concentrations over a broad spectrum of rock composition. Since the majority of elements have a high recovery, it is tempting to incorporate all analyzed elements in an analytical scheme for the evaluation of prospective targets. Thus I developed a new statistical method Mahalanobis Principal Component Analysis (MPCA) that considers element associations for all elements. Mahalanobis distance is used for identifying sample of odd element composition relative to the bulk of element compositions. The scheme is based on assuming that mineralization is not restricted to a few elements (pathfinders) rather than it is a multi-element affair. Principal Component Analysis is employed to determine the contribution of each element to the 'oddness' of the element composition of the anomalous sample. Hence the cause of a sample's abnormal element composition is revealed. Elements with a high contribution to the oddness provide clues about the type of abnormality and its exploration potential. Pearson correlation of samples composition is used for identifying similar samples. Samples of similar element composition share the same rock genesis and belong to the same lineage. Thus by plotting similar samples the spatial distribution of anomalies can be shown and it is used for the further evaluation of the target potential. The more reliable data set 4 acid is used to appraise the exploration potential of the Mt. Freegold sample area using MPAC. Fifteen exploration targets are identified. Not all of them are gold related.
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  Biogeographic history of the world's marmots and the genetic basis of melanism in an Alaskan population of hoary marmots

  Mills, Kendall K.; Olson, Link E.; Drown, Devin M.; Fedorov, Vadim B.; Weber, Jesse N.; Wolf, Diana E. (2024-05)

  This dissertation addresses questions related to the phylogenetics, molting phenology, and genetic basis of melanism in marmots. Marmots (genus Marmota) are large, diurnal ground squirrels that hibernate for 7-8 months each year and have a broad Holarctic distribution. In Chapter 1, I use ultraconserved elements from all 15 extant species to better resolve the phylogeny of Marmota and shed light on the biogeographic history of marmots. The results indicate marmots originated in North America ~16.3 Ma and crossed the Bering Land Bridge into Eurasia ~3-4 Ma. In addition, the Woodchuck (M. monax) and the Alaska Marmot (M. broweri) are more closely related to Eurasian species than to other North American species, and the Hoary Marmot (M. caligata) may be paraphyletic with respect to the Vancouver Island Marmot (M. vancouverensis) and the Olympic Marmot (M. olympus). Chapter 2 is a review of molt phenology in mammals, with a primary emphasis on marmots. Molting is a metabolically expensive process that is generally timed around other costly events such as lactation, parturition, and dispersal. In this chapter I summarize what is known of molting phenology in marmots, which may be particularly informative as to how precise control over molt timing evolved because of the short active period over which molting and all other costly life history events must occur. In addition, I present evidence that the Olympic Marmot only molts once annually, in contrast to other reports that it is the only biannually molting marmot. Chapter 3 is an investigation of melanism in the Hoary Marmot, which is observed in this species only in SE Alaska. I show that melanism is at least partially caused by a gain-of-function mutation in melanocortin-1-receptor (MC1R), a gene that affects melanin deposition in the skin and hair. The mutation affects hair agouti banding such that the middle light band is reduced in length relative to the brown base and black tip, resulting in the melanistic phenotype.
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  A method for automatic surface water extent mapping from Sentinel-1 SAR data for improved response to weather related hazards

  Meyer, Thomas J.; Meyer, Franz J.; Osmanoglu, Batuhan; Maio, Chris (2024-05)

  Torrential rains, flooding, and storm surges are all considered meteorological and hydrological hazards. These hazards can quickly transition into disasters whenever they begin to effect human life or infrastructure. When these disasters occur, they can lead to devastating outcomes such as damage or complete loss of infrastructure, reduced crop yields and related impacts on food security, as well as risks to human life. For decades, these events have been monitored and tracked primarily from visible/infrared sensors. Unfortunately, flooding and storm surges often occur during extensive weather and cloud cover conditions, which can make monitoring these hazards across large spatial scales difficult if not impossible, especially in poorly developed regions. Synthetic Aperture Radar (SAR), with its capability to penetrate through clouds and monitor during both day and night cycles, may provide substantial improvements to flood hazard management, once robust techniques for the detection of surface water extent were developed. This thesis details the development of HYDRO30, an automatic algorithm to map surface water extent from Sentinel-1 SAR data. At its core the HYDRO30 approach automatically creates surface water extent maps by preforming adaptive thresholding on dual-polarized and radiometrically terrain corrected (RTC) SAR images. We use data from the Sentinel-1 C-band SAR constellation as input, as this constellation provides global access to free and open medium resolution SAR data that comes at a reliable sampling rate of six-to-twelve days. Such free-and-open, regularly sampled data is indispensable for hazard monitoring across regional to continental scales. In this thesis, I will show that the HYDRO30 algorithm achieves promising results in delivering robust and accurate surface water extent maps within an efficient timeline. The work presented in this thesis was developed as part of the HydroSAR project, a NASA-funded effort led by UAF to develop an automatic service for the monitoring of weather-related hazards in the Hindu Kush Himalaya. The thesis will also show an application of the HYDRO30 technology for the monitoring of flood hazards in northern Bangladesh during the 2020 south-Asian monsoon season.
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  Improving species identification, age, and life history information for shortraker rockfish (Sebastes borealis) in Prince William Sound, Alaska, using sagittal otolith analyses

  McNeel, Kevin W.; Kruse, Gordon H.; Mueter, Franz J.; von Biela, Vanessa R.; Black, Bryan A. (2024-05)

  Shortraker rockfish (Sebastes borealis) are a long-lived species found in the North Pacific Ocean. Limited life history information compels fishery managers to apply conservative estimates of allowable bycatch for this species. To improve the available life history information, we analyzed sagittal otoliths, targeting fish from Prince William Sound, to assess (1) age estimation errors, (2) species misidentification, and (3) relationships between environmental factors and annual growth. To assess errors in age data, otoliths were analyzed for core Δ¹⁴C activity. Those values were compared with bomb radiocarbon reference curves for other North Pacific species (i.e., known age Pacific halibut, Hippoglossus stenolepis, and yelloweye rockfish, S. ruberrimus). Shortraker rockfish Δ¹⁴C activity followed reference curves, partially validating current age estimation techniques. To identify species, otolith shape analyses were performed on putative shortraker and rougheye rockfish (S. aleutianus). Clusters of shortraker, rougheye, and blackspotted rockfish (S. melanostictus) data were identified using random forest algorithms and otolith wavelet estimates. Misidentification rates were examined using out-of-sample error estimates and otoliths from fish whose species was validated using single nucleotide polymorphisms. Model classification errors suggest that historically assigned species were accurate and shortraker rockfish can be identified with 94% success. To investigate potential drivers of fish growth, a chronology of shortraker rockfish otolith increment widths was developed and related to environmental variables using dendrochronology methods. Model comparisons showed significant correlations between annual increment widths (i.e., an indicator of fish somatic growth) and environmental variables, specifically negative correlations with winter temperature at depth, spring surface salinity, and the North Pacific Gyre Oscillation, and positive correlations with spring and winter upwelling and the Pacific Decadal Oscillation 2-years earlier. These three analyses validate and improve data and life history information and support incorporating age and growth data into stock assessment models used to calculate allowable bycatch levels for shortraker rockfish.
• Analyzing vegetation effects on snow depth variability in the Caribou Poker Creeks Research Watershed, Alaska

  May, Lora Dawn; Stuefer, Svetlana; Goddard, Scott; Panda, Santosh; Barnes, David (2024-05)

  Seasonal snowpack plays a critical role in hydrologic and ecologic processes. In boreal forest regions snow depth is known to be markedly different across land cover types. Identifying the vegetation metrics responsible for possible snow depth and snow water equivalent (SWE) spatial variability continues to be a challenge. Airborne lidar has advanced our understanding of links between forest snow distribution and vegetation impacts. This study analyzes high resolution (0.5 meter) lidar data sets acquired during NASA's SnowEx field campaign in Alaska and compares them statistically across the vegetation metrics of land cover class and lidar-derived canopy height. Airborne lidar data was collected for a boreal forest site, the Caribou Poker Creeks Research Watershed (CPCRW), during snow-off and peak snow-on accumulation in March of 2022 and May of 2023. Lidar snow depth (98 ± 15 cm) and canopy height maps, both at 0.5 m resolution, were created from lidar data sets. Lidar snow depth and canopy height maps were resampled to 1.5 m resolution to account for spatial autocorrelation. A total of 85.9 million lidar snow depth and canopy height values were available for this study. Three subsets totaling 6.1 million snow depths and canopy heights were processed to run the analysis. A USGS National Land Cover Database (NLCD) 2016 map of Alaska was used to determine land cover classes. Extensive in situ field snow depth measurements were collected concurrently with the peak snow-on lidar survey and were used to validate lidar accuracy. Analysis results from the three subsets showed statistically significant differences in median snow depths for all land cover classes and canopy height (p < 2.2e-16). Statistical comparison within land cover classes showed the largest significant difference in snow depths between shrub and deciduous forest (6-15 cm) and shrub and wetlands (7-14 cm). For canopy height classes, forest and treeless (12-14 cm) and forest and shrub/short stature trees (SSS) (8-14 cm) had snow depths that were significantly different. This thesis will further summarize results on quantifying snow depth variability between land cover and canopy height classes within boreal forests using NASA SnowEx Alaska data.
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  Nurturing teacher agency to influence teacher professionalism through teacher action research

  Martin, Karen J. A.; Kaden, Ute; Gifford, Valerie; Topkok, Sean Asikłuk; Ickert-Bond, Stefanie (2024-05)

  The research described in this study sought to understand how teacher agency was influenced by engaging teachers in action research-based professional development. Teacher agency is a critical component of teacher professionalism and nurturing teachers to recognize and enact greater agency has the potential to elevate the profession of teaching. A mixed methods methodology was employed to study the lived experience of six teachers who engaged in teacher research in a rural Alaskan school district. The research addressed this overarching question: How does engaging teachers in action research-based professional development about their professional practices influence teacher agency? In addition, data was collected to understand these supporting research questions: 1) How does participating in the action research-based professional development influence teachers' professional practices? 2) How does participating in the action research-based professional development influence collaborative practices? Findings and results suggest that the teachers' agency was influenced in the following ways: teacher engagement, knowing impact, empowerment by trust, and critical consciousness. Findings and results suggest that the teachers' professional practices were influenced in the following ways: intention and design, research capacity, determining impact, and dispositions. Findings and results suggest that the teachers' collaborative practices were influenced in the following ways: shared experience and a culture of willingness to learn. Convergence was observed between qualitative results and quantitative findings. Implications for influencing teacher agency through specific contextual conditions of professional learning and development are discussed and recommendations for the direction of future research.

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