• Influence of environmental attributes on intertidal community structure in glacial estuaries

      McCabe, Mary K.; Konar, Brenda; Iken, Katrin; Kelley, Amanda (2021-05)
      High-latitude coastal environments are experiencing dramatic changes due to climate warming. Increased glacier discharge rates modulate downstream environmental conditions in coastal watersheds. These fast-changing environments are predicted to influence the structure of nearshore marine communities. Here, rocky intertidal community structure, recruitment of key organisms, and environmental correlates were examined at nine watersheds in two regions (Kachemak Bay and Lynn Canal) that bookend the Gulf of Alaska, which were separated by approximately 1000km. Each watershed was part of a gradient in each of the regions that spanned 0-60% glacial coverage. Percent cover, biomass surveys, and recruitment of intertidal organisms, along with environmental monitoring of salinity, temperature, dissolved oxygen, river discharge, turbidity, and nutrient loading were completed from April - September 2019 in each watershed. Biological community structure and variance were analyzed by taxa and by ecological group (i.e., primary producer, filter feeder, omnivore, grazer, predator) and then in relation to the local environmental spatiotemporal profiles. In general, larger watersheds with more glacial coverage and river discharge resulted in higher cover of primary producers and less cover of filter feeders. This pattern was more apparent in the region with more oceanic influence as compared to the other region located within an inlet. In relation to specific environmental drivers, salinity was negatively correlated with primary producer cover (r = -0.52), but positively associated with barnacle cover (r = 0.40). Additionally, turbidity was positively correlated with primary producer biomass (r = 0.50), but negatively correlated with mussel cover (r = -0.30). In contrast, there was a positive relationship among mussel recruitment and discharge and turbidity. There was variability in within-ecological group response between regions that could be a response to local circulation and oceanic influences. Barnacles were the main filter feeder species driving patterns in the more saline region located close to the open ocean, while mussels drove patterns in the other less oceanic region. As glaciers recede, environmental conditions, such as salinity, will increase and turbidity will decrease, which may alter future intertidal community assemblages dominated by filter feeders.
    • Integration of remote sensing technologies into Arctic oil spill response

      Garron, Jessica I.; Meyer, Franz; Trainor, Sarah; La Belle-Hamer, Nettie; Lee, Olivia; Mahoney, Andrew (2020-12)
      Identifying the tools and pathways to successful integration of landscape level science into decision-making processes is vital for quality environmental stewardship. Remote sensing information can provide critical facts to decision makers that historically were only available via manned airplane flights and ground truthing expeditions. Remote locations like the Arctic are well suited for monitoring with remote sensing tools due to the lack of transportation infrastructure and communications bandwidth. Remote sensing tools can be valuable when monitoring specific Arctic targets like ocean going vessels, sea ice, coastal erosion, off-shore resource development infrastructure, and oil spills. This dissertation addresses how to mount a more efficient and informed response to Arctic oil spills by capitalizing on available RS tools. I posed three research questions to frame this work, 1) What remote sensing tools are currently available, as compared to those currently used in the Incident Command Structure of an oil spill response? 2) Are there barriers to additional remote sensing tool use for oil spill response support? 3) What process changes can improve or increase remote sensing data use in oil spill detection and response? I conducted a four-phased, exploratory sequential mixed methodological study to examine current remote sensing capacity and solutions to expand remote sensing use in support of oil spill response. Phase One defined the remote sensing tools available to support oil spill response, identified how those tools are being used in support of oil spill response actions, and was used as the foundational research to inform the following phases of the study. Phase Two used cloud-processing resources to establish an automated oil detection pipeline. Phase Three addressed human-driven barriers to remote sensing tool use identified in phase one through remote sensing tool training, knowledge coproduction, and remote sensing data integration into oil spill response exercises. Synthesizing all components of Phases One, Two and Three, a remote sensing protocol for the use of unmanned aircraft systems in support of oil spill response was developed and integrated into U.S. Coast Guard operational policy in Alaska to complete Phase Four of this research. This research identifies opportunities and solutions that support improved Arctic oil spill response decision-making through the application of remote sensing data and information.
    • Interpretations of climate change on grazing systems: the comparison of Arctic and Subarctic carex

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

      Brazhnikov, Dmitry; Simmons, Harper; Kowalik, Zygmunt; Johnson, Mark; Marchenko, Alexey; Horrillo, Juan J. (2021-05)
      Surface tides, when obstructed by bottom relief, give rise to periodic oscillations within the stratified oceanic interior. Such transformation of the depth independent (barotropic) tide into internally propagating (baroclinic) waves comprises 1/3 of the global energy losses from the surface tide. Internal waves of tidal period known as internal tides tend to have low vertical shear and hence are very stable and long lived. They have been observed to propagate essentially unchanged across ocean basins. Details of the internal tide wave life-cycle are not well known, yet turbulent dissipation powered by the slow decay of these waves is one of the key processes shaping deep ocean water properties. The Tasman Sea stands out as a natural laboratory to investigate the internal tide life cycle. In this dissertation, the generation and propagation of internal tides were examined by means of realistic simulations of ocean circulation under varying conditions, and were compared to observations obtained during the Tasman Tidal Dissipation Experiment (TTIDE). The simulations reveal that the barotropic-to-baroclinic conversion is intensified at the Macquarie Ridge near New Zealand by coupling with secondary, nonlocally produced internal tides. Because of this complexity, regionally varying hydrographic conditions drive remarkable temporal and spatial variability of internal tide generation. The internal tides that are created at the ridge constructively superpose into a spatially confined, beam-like feature (Tasman beam) that radiates across the Tasman Sea over 1000 kilometers from its generation region and reaches the Tasman shelf. The beam is described well at first order by simple plane wave propagation theory, but also exhibits non-plane wave characteristics associated with diffraction. Additional intricacy arises from development of a standing wave, the result of the beam's reflection near Tasmania. Temporal changes include hydrography-induced refraction and strong perturbations from interactions with eddies. It is concluded that in-situ mooring measurements and ship surveys of internal tides exhibit a great deal of apparent spatial and temporal variability that can be difficult to interpret. This variability can largely be eliminated in the analysis of numerical models which allow the underlying wave field energy life cycle to be quantified.
    • Investigations on the impacts of ship traffic in the Bering Sea on aerosol optical depth using automatic identification systems data, and MODIS collection 6.1 data

      Summers, Tyler; Mölders, Nicole; Friberg, Mariel; Fochesatto, Javier (2021-05)
      Increasing Arctic shipping requires study of the increasing aerosol emissions impact on aerosol optical depth (AOD) in the Bering Sea and the Bering Strait. This study used Moderate Resolution Imaging Spectroradiometer (MODIS) 550 nm AOD 3 km products to study the seasonal variability over the length of the Arctic shipping season, from June to October, over 2011 and 2014. Bucket resampling was used to project and downscale the MODIS AOD to a 0:25 by 0:25 grid during overpasses. An overpass is dened as consecutive MODIS granules from both the Terra and Aqua satellites. Ship positional data obtained from automatic identication systems (AIS) was aggregated to hourly data. Collocation of ships and AOD from overpasses were determined for all quarter degree grid cells and times. Area-weighted means for both grid-cells with ship occurrence and without ships were determined for each month. AOD decreases with increasing time in the shipping season due to the increasing frequency of low pressure system and hence aerosol removal via washout and scavenging. Comparison of the AOD of 2011 and 2014 revealed that the position of the Aleutian Low not only strongly aects the sample size, but also AOD over the Bering Sea. The sea-ice area seemed to be without notable impact on the number of ships and AOD. A weak positive correlation was found between AOD and the number of ships present in the same grid cell during a overpass for 7 out of the 10 months. A strong skewing towards October occurred in 2011 due to a strong positive correlation of the number of data points.
    • It's complicated: immigrant parents in Alaska navigating the process of raising bilingual children

      Dosch, Katerina; Sickmann, Sabine; Marlow, Patrick; Martelle, Wendy (2021-05)
      This qualitative study investigates the process of raising bilingual children in Fairbanks, Alaska. The study was guided by an overarching question: Why do some children in bilingual families become bilingual speakers, whereas other children who also have the chance to become bilingual do not? From that, two main research questions have evolved. 1. What are the elements involved in raising bilingual children in Fairbanks, Alaska as reported by the parents? 2. What is the role of a family's place of residence on their children's bilingualism? Data were collected through a socio- demographic questionnaire, semi-structured in-depth interviews, and focus groups. Three rounds of interviews were conducted with each participating family - an initial interview, a follow up interview, and a focus group interview. Seven families participated in the study and only parents were interviewed. These families consisted of either first generation immigrant parents (sharing or not sharing the same native language) or parents in mixed marriages (immigrants married to native- born Americans). Over 19 hours of data were audio recorded, manually transcribed ad verbum, and analyzed. From the method of grounded theory data coding, groups of elements that are involved in the process of raising bilingual children and the development of children's heritage language (HL) emerged, namely: parental and children's HL related actions, factors influencing bilingualism, factors determining bilingualism, and place of residence. The findings suggest that the process of raising bilingual children is positively or negatively influenced and determined by a complex net of interconnected elements. Raising bilingual children, thus, rests on a combination of supportive and detrimental elements, which are in a constant struggle. It seems that the process of raising bilingual children can absorb a certain amount of detrimental elements without collapsing. Considering the elements involved in raising bilingual children, it is not only parents and their actions that play an important role in the process of raising bilingual children. While parents are the instigators of the process, children greatly influence parental actions connected to the transmission of the HL. The findings of this study suggest though, that children and their actions alone do not decide if the process fails or succeeds. Parents seem to be able to mitigate children's detrimental influences (if they exist) through their consistent use of the HL. On the other hand, some parents hinder their own efforts either through their fears, beliefs, or other personal limitations. Finally, based on the data, place of residence does not seem to play a significant role in the process. Some parents are able to raise bilingual children despite living in a place that poses challenges to bilingual families. These parents are able to overcome obstacles through their own efforts and consistency of the HL use.
    • Landscape characteristics influence climate change effects on juvenile chinook and coho salmon rearing habitat in the Kenai River watershed

      Meyer, Benjamin; Rinella, Daniel; Wipfli, Mark; Schoen, Erik; Falke, Jeffrey (2020-08)
      Changes in temperature and precipitation as a result of ongoing climate warming in south-central Alaska are affecting juvenile salmon rearing habitat differently across watersheds. Work presented here simulates summer growth rates of juvenile Chinook and coho salmon in streams under future climate and feeding scenarios in the Kenai River (Alaska) watershed across a spectrum of landscape settings from lowland to glacially-influenced. I used field-derived data on water temperature, diet, and body size as inputs to bioenergetics models to simulate growth for the 2030-2039 and 2060-2069 time periods, comparing back to 2010-2019. My results suggest decreasing growth rates under most future scenarios; predicted changes were of lower magnitude in the cooler glacial watershed and main stem and more in montane and lowland watersheds. The results demonstrate how stream and landscape types differentially filter a climate signal to juvenile rearing salmon habitat and contribute to a broader portfolio of habitats in early life stages. Additionally, I examined two years of summer water temperature data from sites throughout our study tributaries to assess the degree to which lower-reach sites are representative of upstream thermal regimes. I found that the lower reaches in the lowland and glacial study watersheds were reasonably representative of daily and seasonal main stem thermal conditions upstream, while in the montane study watershed (elevation and gradient mid-way between the lowland watershed) upstream conditions were less consistent and thus less suitable for thermal characterization by a lower-reach site alone. Together, this work highlights examples of the importance of accounting for habitat diversity when assessing climate change impacts to salmon-bearing streams.
    • Liberal deradicalization in the adaptation of novels to film: defining antiheroes, from Heathcliff to Walter White

      Kraft, Benjamin; Carr, Richard; Hirsch, Alexander; Harney, Eileen (2021-08)
      Using research from the history of the Victorian novel and recent media, I demonstrate the value in re-examining the critical importance of the antihero. Using a methodology of combining neo-Marxian analysis, adaptation studies, and a re-thinking of what constitutes novels and television serials, I explore how antiheroes are defined and why those definitions are often not inclusive to controversial, but seemingly definitional antihero examples. As informed by a critique of how antiheroes are defined, I use my research to discuss the underlying characteristics of the antihero across genres. From a perspective of critiquing liberalism adopted from Emily Brontë's Wuthering Heights and Vince Gilligan's Breaking Bad, I structure textual evidence in support of antiheroes being identified according to three traits: sympathy, violence, and radical speech. The literary and real-world impact of each trait is argued according to evidence qualified by a neo-Marxian methodology, using an original synthesis of Louis Althusser's aleatory politics and the Marxist cultural critiques of Raymond Williams. Finally, these three traits are strongly evinced in the real-world systemic critiques of liberalism represented in both Heathcliff and Walter White.
    • Life cycles of the kelps Saccharina latissima and Alaria marginata: implications for mariculture and ecology in Alaska

      Raymond, Annie E.T.; Stekoll, Michael S.; Eckert, Ginny L.; Bergstrom, Carolyn A. (2020-08)
      Kelp farming has the potential to economically diversify coastal communities of Alaska while offering other ecosystem services, including carbon sequestration and mitigation of eutrophication. Two bottlenecks to the expansion of the industry are understanding the natural kelp life cycle and manipulating the life cycle to produce seed. We address these questions with specific research aimed to increase knowledge of the expected natural variability of the kelp life cycle and test methods to effectively manipulate storage of kelp seed string to add flexibility to the kelp farming industry. First, in Chapter 1, we documented the patterns of sporophyte fertility for two commercially important kelp species, Saccharina latissima and Alaria marginata, in the wild. We found S. latissima exhibited both annual and perennial life history varying by location and year, with an increasing proportion of fertile sporophytes present in the fall and winter season. In contrast, A. marginata displayed a predictable annual life history, recruiting in spring with the proportion of fertile sporophytes increasing into the fall. Results from Chapter 1 suggest A. marginata has a more reliable brood stock availability and, therefore, has the potential to be a suitable commercial crop. Ecologically, Chapter 1 results suggest A. marginata may contribute consistently to habitat across Alaska in spring and summer months. In Chapter 2, we tested how different culture conditions, including light, temperature, and culture media, affected gametophyte growth with the goal of developing storage methods for kelp seed string. We found that low temperature is effective in slowing gametophyte growth and reducing gametogenesis and is the best condition for seed storage. Further experiments tested how storage in cold temperatures affects seed quality, leading to the development of a method called "cold banking," which enables extended seed storage or staggering of seed string for at least an additional thirty-six days in a storage setting without adverse effects to sporophyte density and length at the time of outplanting and up to three weeks after outplanting. Ecologically, Chapter 2 results demonstrate the diversification of microscopic stages used as an overwintering strategy by S. latissima. As the kelp mariculture industry is expected to grow in Alaska and around the world, we hope this information will be a jumping-off point for research promoting productive and sustainable commercial kelp production.
    • Lipid accumulation in three species of Neocalanus copepod in the northern Gulf of Alaska

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

      Priest, Justin T.; Sutton, Trent M.; Mueter, Franz J.; Raborn, Scott W. (2020-08)
      Environmental conditions influence the presence, species composition, abundance, and growth of fish species in the nearshore Arctic ecosystem. With ongoing shifts in Arctic conditions due to climate change, how fish communities and individual species respond to such changes to environmental variability more broadly is unknown. This study analyzed catch and length data from a long-term fish monitoring project near Prudhoe Bay, Alaska, 2001-2018, to quantify the effects of environmental variables on the overall fish community and on the juveniles of two important whitefishes, Arctic Cisco Coregonus autumnalis and Broad Whitefish Coregonus nasus. Abundance data (n = 1.78 million fish) from daily sampling (July-August) at four stationary sampling locations showed distinct shifts in fish community metrics. Since 2001, annual species richness has significantly increased by one species per decade while water temperature warmed by over 1.4°C. The species composition based on biweekly catch data has significantly changed across years, with distinct variations among sample locations and throughout the season. Species composition was significantly affected by both salinity and water temperature. The effects of environmental conditions on growth showed that water temperature was positively and linearly associated with increases in growth for juvenile whitefish, while salinity negatively affected growth of age-0 Arctic Cisco. Changes in the abundance of juvenile whitefishes were related to both water temperature and salinity. Results from all analyses suggest that species positively associated with observed warming in the aquatic environment are generalist species such as Broad Whitefish. This study concluded that continued climate change, and especially Arctic warming, will likely increase growth, change the species composition, and alter abundance in the Arctic nearshore ecosystem. These changes will have impacts on subsistence harvests and on upper trophic level species that prey on nearshore fishes.
    • Mental health problems in the mountains: needs, assets, and recommendations for managing mental health problems in mountain-focused wilderness-based education and related fields

      Johnson, Samuel H.; Dulin, Patrick L.; Lopez, Ellen D. S.; Gifford, Valerie M.; Rivkin, Inna D. (2020-08)
      Background: Through controlled exposure to stress, wilderness-based education programs can buildcapacity for adaptive coping and produce long lasting improvements to participants' quality of life.However, stress can also overwhelm them, resulting in the emergence and exacerbation of mental health vulnerabilities in the field. However, empirically grounded best practices for training, pre-trip screening, and protocol/policy for mental health specific to the wilderness context are not well developed. Aim: The aim of this study was to assess needs and assets, and develop recommendations for training, pre-trip screening, and organizational protocol/policy to assist with successful management of mental health problems in mountain-focused, wilderness-based education and related fields such as outdoor leadership, guiding, environmental education, snow safety, search and rescue, and wilderness therapy. Methods:A pragmatic, two phase, sequential mixed methods approach was utilized to explore this topic within the context of an overarching collaborative community based participatory research (CBPR) framework with organizational partners: National Outdoor Leadership School, Outward Bound USA and Canada, the Wilderness Risk Management Conference, and the Alaska Mountaineering School. A preliminary quantitative study utilized a cloud-based survey to determine baseline characteristics for 64 wilderness-based educators, guides, outdoor leaders, snow safety professionals, and search and rescue personnel. Qualitative interviews with 16 experienced and prepared key informants addressed the study aim in more depth, consistent with partnering organization priorities, in the tradition of CBPR. Findings: Mental health topics and skills are underemphasized in current training, and training was found to be of less value than personal and professional experiences with mental health. In the future, mental health should be increased and emphasized, possibly through the utilization of existing resources such as the stress continuum or curriculum such as Psychological First Aid as well as practical training opportunities that emphasize experiential learning around mental health. Current screening can present both risks and benefits for clients, instructors, and organizations. Nondisclosure and the impacts of stigma and prejudice on the interpretation and utilization of mental health screening information were major concerns. However, screening can guide preventive and proactive efforts, and build working relationships with potential participants. Future screening should be used to inform participants about course stress, encourage disclosure, and direct curriculum development. Multi-step screening, utilizing multiple interactions with participants before the course, was identified as a utilitarian way to facilitate improvements for future screening. In protocol/policy, field management of mental health problems is underemphasized relative to evacuation, resulting in overutilization of disruptive evacuation processes. While many organizations do well at responding to instructor mental health needs after incidents such as a fatality in the line of work, inconsistencies in implementation can create unintended barriers to instructor self-care. Future protocol/policy should prioritize instructor mental health by addressing inconsistencies in implementation, removing barriers to self-care and guiding the deployment of resources such as responsive staffing or free counseling benefits. Implications: This study contributes uniquely to the literature by providing an empirically-based perspective into a little researched topic, and multiple avenues for implementation of findings such as increasing mental health content and experience-based training, utilization of multi-step screening processes, and consistent implementation of organizational protocol/policy in support of client and instructor mental health. Recommendations for implementation address weaknesses and build upon strengths already present in training, screening, and protocol/policy. Overall, practice and research in this area are in need of further investigation and development. Future dissemination, research, and practice development could help develop measures or resources to support the improvement of training, screening, and protocol/policy across wilderness-based education and related fields.
    • Metabolite influence on the hibernating Arctic ground squirrel

      Rice, Sarah A.; Drew, Kelly; Kuhn, Thomas; Coker, Robert; Ritter, Robert (2020-12)
      Hibernation is a state of extreme metabolic plasticity and fasting. How hibernators maintain nitrogen homeostasis and regulate amino acid metabolism and how those metabolites influence hibernation physiology remains unknown. We first utilized three approaches to understand nitrogen homeostasis and amino acid metabolism in hibernation: longitudinal metabolic profiling within individual animals over undisturbed torpor, in vivo amino acid isotope tracing in deep torpor, and ¹⁵N isotope tracing in vivo during arousal from hibernation in Arctic Ground Squirrels (AGS). We observed that in vivo whole body production (WBP) of metabolites in deep torpor are profoundly and selectively suppressed in deep torpor. Metabolic profiling over undisturbed torpor bouts shows amino acids with nitrogenous side chains accumulate over torpor while urea cycle intermediates remain unchanged. During arousal from hibernation, ¹⁵N isotope tracing demonstrates recycling of free nitrogen into non-essential amino acids, essential amino acids and the gamma-glutamyl system. We next utilized two approaches to understand potential metabolite influences on thermogenesis and behavior in hibernation: we infused ammonium acetate in deep torpor and fed diets high in omega 3 fatty acids and monitored body temperature and torpor bout length. We found high doses of a nitrogen donor, ammonium acetate, as well as diets high in omega 3 fatty acids both influence thermogenesis in hibernation. In conclusion, production of metabolites in deep torpor indicate highly regulated metabolism with accumulation of nitrogen carrying amino acids. We additionally show metabolites and nitrogen can exert thermogenic influence on hibernating AGS.
    • Meteorological drivers of lightning in Alaska on seasonal and sub-seasonal timescales

      Chriest, Jonathan; Bhatt, Uma S.; Bieniek, Peter A.; Walsh, John E. (2021-05)
      Wildfire has long been a part of the Boreal forest ecosystem in Alaska and the increasing number of large fire seasons over the past 2 decades has had substantial economic and health impacts. Boreal wildfires are expected to continue to increase over the next century in part due to a projected increase in lightning. This motivates developing lightning outlooks to inform fire management decisions regarding the economic allocation of shared firefighting resources including but not limited to personnel and air tankers. The goal of this research is to identify key meteorological parameters associated with lightning processes on a stroke-by-stroke spatial scale and at hourly-to-sub-seasonal timescales. This is a first step towards developing robust lightning outlooks. In order to identify the key parameters, lightning data for the Alaska Lightning Detection Network was paired with hourly European Center Reanalysis Version 5 (ERA5) over the 2012-2019 study period. This data was analyzed on the scale of Alaska Fire Service Predictive Service Areas (PSAs) and three sub-seasons of the Alaska fire season. This strategy helped to identify regional and sub-seasonal variability and made the research operationally relevant. Key results from this research include the following. The majority of lightning occurs in the duff driven sub-season across all PSAs. Lightning, particularly in the Interior PSAs, follows a diurnal pattern with lightning on average beginning earlier in the day in the eastern portion of Alaska and later in the day in the western portion of Alaska. This distinctive pattern is not as well defined in the Coastal PSAs. Results also suggested that dry lightning may be more prevalent in portions of the western Interior than in other regions of Alaska. Lightning events were more common under specific atmospheric flow directions at 500 and 700 hPa, where these directions varied by PSA. Northeasterly and northwesterly flow aloft were most favorable for lightning in the Tanana Valley West PSA, while southerly flow aloft was more favorable for lightning in the North Slope and Upper Yukon PSAs. Finally, easterly flow was a more common pattern during lightning strokes in the Seward Peninsula and Kuskokwim Valley PSAs.
    • The mineralogical associations, distribution, and mineral zoning of cobalt in the Bornite deposit, southwest Brooks Range, AK

      Mahaffey, Zachary B.; Newberry, Rainer; Schrader, Christian; Regan, Sean (2021-08)
      The Bornite Cu-Co deposit is predominately hosted in dolomitic marble with interstratified phyllite; the mineral resource is restricted to the Upper, Lower and South Reefs. Cobalt is primarily from carrollite (ideally CuCo₂S₄), cobaltite (ideally CoAsS), and cobaltiferous pyrite ((Fe,Co)S₂). The Co minerals can contain significant Ni, and the Ni rich endmembers, millerite (NiS) and gersdroffite (ideally NiAsS), also rarely occur. Detailed handheld XRF analyses on 15 drill holes, coupled with reflected light petrography, electron microprobe-based compositional maps, and electron microprobe analyses (EPMA) have shown complex compositions, textures, associations, and spatial distribution of the Co minerals in the Bornite deposit. Carrollite compositions and textures vary with the Cu-sulfide assemblage: carrollite with bornite is commonly porphyroblastic and approximated by Cu(Co,Ni)₂S₄, whereas carrollite lacking associated bornite is interstitial and represented by (Cu,Ni)(Co,Ni)₂S₄. Cobaltite occurs in two generations: early As-depleted, Ni-poor, and metastable ((Co,Fe)As₀.₅S₁.₅ to (Co,Fe,Ni₀.₀₆)As₀.₈₈S₁.₁₂), and late near stoichiometric ((Co,Fe,Ni₀.₀₁)As₀.₉S₁.₁ to (Co,Fe,Ni₀.₉₄)As₁S₁). The latter rims and (or) replaces the former. The virtual lack of cobaltite in assemblages containing bornite + pyrite, along with carrollite compositions, suggest a gradient in Cu and Co activity that increased with increasing fS₂. Distinct carrollite zones associated with higher Cu grades are present in the high-grade zone (Number One Orebody) of the Upper Reef and the South Reef. Decreasingly Cu-rich assemblages dominated by chalcopyrite + pyrite and cobaltite are outside the carrollite zones. The Lower Reef has lower Cu grades, lacks a carrollite zone, and variably contains cobaltite. Due to these different Co mineral distributions, the Bornite deposit cannot represent dismemberment of a single homogeneous body. Bornite pyrite can contain Ni and Cu (both inversely correlated to Co) and As (maximum 5.6%, generally correlates with Co). Compositions of Co-pyrite lacking significant As (up to 8.5% Co) and late cobaltite suggest temperatures of 400-500℃, consistent with Upper Blueschist to Greenschist conditions. Pyrite compositions can be extremely variable within a single sample and even within a single grain: nearly half of all EPMA pyrite analyses yield < 0.25% Co. Clearly metamorphic (porphyroblastic) pyrite displays concentric oscillatory Co + As zonation. Average Co content in pyrite generally increases with Cu grade, which suggests Devonian Co and Cu deposition occurred simultaneously. Co deportment is a function of location in the deposit, which correlates with Cu grade and Co mineral zonation. Based on metal balance calculations, more than half (on average 57%) of the Co in South Reef intervals with > 0.5% Cu is due to Co-pyrite. In the Lower Reef the proportion is much higher: 55-93%. High Cu grade intervals typically yield increased carrollite abundance and decreased cobaltite. Carrollite consistently reports to the Cu concentrate, however, cobaltite recovery is variable and can report to the tails with Co-pyrite. Thus, maximizing Co recovery from Bornite will require producing a pyrite concentrate in addition to the Cu concentrate.
    • Modeling permafrost dynamics and water balance of Arctic watersheds in a changing climate

      Debolskiy, Matvey Vladimirovich; Hock, Regine; Romanovsky, Vladimir E.; Alexeev, Vladimir A.; Nicolsky, Dmitry J. (2020-12)
      Changes in climate across the Arctic in recent decades and especially the increase of near-surface air temperature promote signicant changes in key natural components of the Arctic including permafrost (defined as soil experiencing subzero temperature for more than two consecutive years). Recent borehole observations exhibit signicant increase in ground temperatures below the depths of seasonal variations. Modeling studies on a global scale suggest a steady decrease in area underlain by near-surface permafrost in the northern hemisphere in recent decades. Global projections for the next century predict further permafrost degradation depending on the greenhouse gas concentration trajectory. Permafrost degradation is not only associated with climate feedbacks but can also result in signicant changes in coastal and terrestrial ecosystems and increased risks of costly infrastructural damage for Arctic settlements. In addition, permafrost plays an important role in the terrestrial part of the Arctic freshwater cycle as the volumes of frozen ground are practically impermeable for subsurface moisture transport and contain excess water in the form of ground ice. Since geophysical observations bear signicant costs in the Arctic, especially in the remote areas, simulations performed with physically based numerical models allow researchers to assess the current state of permafrost in Arctic regions and make future projections of its dynamics and resulting hydrological impacts. In this dissertation we use numerical modeling in two distinct ways: 1) to estimate current and future ground temperature distribution with high resolution on a regional scale and 2) to evaluate the role permafrost degradation plays in changes in water balance of watersheds under changing climate. First, we study the permafrost evolution of the Seward Peninsula, Alaska over the 20th and 21st century using a distributed heat transfer model. Model parameters are calibrated with a variational data assimilation and are distributed across the study domain with an ecosystem type approach. Simulations suggest that the peninsula will experience a reduction in the near surface permafrost extent of up to 90% and an average increase in ground temperature across the peninsula up to 4.4°C towards the end of the 21st century under the high greenhouse gas concentration trajectory. Second, we perform an ensemble of millennia-long experiments by simulating hypothetical idealized small-scale watersheds placed in a typical Sub-Arctic setting with a physically based distributed hydrological model. In these experiments we single out the effects of temperature dependent subsurface moisture transport by applying air temperature change in our forcing scenarios only to sub-zero temperatures within a given year. Results suggest a long-term increase in annual runoff of 7-15% and a similar decrease in evapotranspiration under a prolonged (up to a millennia) air-temperature increase. The short-term (< 100 years) water balance response highly depends on soil permeability and the watersheds slope and profile curvature. The simulated changes in water balance are a direct result of the decrease in near- surface soil moisture and intensified subsurface moisture transport in the deeper soil layers due to the permafrost thaw. Additional experiments suggest that simplied models that do not include lateral subsurface moisture transport, as typically done in Earth System Models, can reproduce similar changes in equilibrium water balance to the ones predicted by more sophisticated models for the watersheds with gentle slopes. We also find that if the air temperature trend is reversed and watersheds are experiencing prolonged cooling, a high degree of hysteresis in water balance behavior can be observed, however, the long-term changes in water balance are equal in their amplitude. Additionally, we find that initial soil moisture distribution in the deeper soil which is essentially a consequence of the paleoclimate (given the same permeability and topography) determines the overall soil moisture storage deciency which in turn results in the lag between the onset of warming and the increase in total runoff. The deficit in soil moisture storage is highly dependent on the watersheds topography.
    • Modeling supraglacial lake drainage and its effects on the seasonal evolution of the subglacial drainage system in a tributary glacier setting

      Franco, Nevil Arley; Truffer, Martin; Wackerbauer, Renate; Delamere, Peter (2021-08)
      This work aims to gain a better understanding of the relationship between glacier motion and water distributed through subglacial drainage systems. A numerical scheme (GlaDS) is used to model both inefficient and efficient drainage systems to see which dominates after the draining of a supraglacial lake on a synthetic glacier that is made up of an outline that features a main branch and a tributary. The geometry is based on the surgetype Black Rapids Glacier (Ahtna Athabascan name: Da lu'itsaa'den) in Alaska, where a lake develops in the higher ablation zone, and drains rapidly early in the melt season. It has also been observed that this lake drainage causes a twofold or threefold speed-up of the main branch, with some acceleration of the lower-lying Loket tributary. This speed-up can be considered a surrogate for a surge, which also initiates in the main branch, while, during times of quiescence, the ice flow on the tributary is dominant. We investigate the effects of varying timing and volume inputs of lake drainage with a focus on its effects beneath the tributary. We find that the response of the glacier depends on the seasonal timing, the amount of water from the draining lake, and its location on or near the margins of the glacier. Results show that an inefficient drainage system is the cause of the glacier speed-up, both when the lake drains rapidly or when there is an extended time in drainage, at any time of the season. The speed signals vary throughout the glacier depending on the location of the lake relative to that of an evolved efficient drainage system.
    • Neuroendocrine and glial cell remodeling in a hibernating mammal

      Duncan, Cassandra; Williams, Cory; O'Brien, Kristin; Christian, Helen (2021-08)
      In most seasonally breeding vertebrates, changes in photoperiod trigger the remodeling of neuroendocrine and glial cells known to be involved in activation of the reproductive axis. We used electron microscopy to determine whether similar remodeling occurs under conditions of continuous darkness during hibernation in arctic ground squirrels (Urocitellus parryii). Immediately prior to the reproductive season, arctic ground squirrels naturally sequester themselves in a persistently dark hibernacula for 6-8 months where they experience only muted fluctuations in ambient temperature. Hibernation consists of two to three week-long bouts of torpor, during which body temperature and metabolism are depressed, periodically interrupted by short (<24h) interbout arousals where animals become euthermic and metabolism returns to "normal" levels. Although their exact functions are unknown, interbout arousals are generally thought to be associated with homeostatic processes. With the exception of brief dynamic changes during interbout arousals, brain activity and neuroendocrine pathways are generally thought to be relatively static across hibernation. We hypothesized that interbout arousals may allow for cellular ultrastructural remodeling of pars tuberalis thyrotroph cells, hypothalamic tanycytes, and pars distalis gonadotroph cells across hibernation, allowing for animals to activate their reproductive axis in anticipation of the active season. To test this, we sampled brains from arctic ground squirrels during early, mid-, and late hibernation, as well as post hibernation. We found evidence for cellular remodeling and activation of the reproductive axis across hibernation including decreases in neuronal contacts with the hypothalamic basal lamina, increases in the cell area and decreases in granule density of pars distalis gonadotrophs, increases in gonadal mass, and upregulation of steroidogenic genes in gonadal tissue. We hypothesize that the return to euthermy during interbout arousals allows for remodeling of the hypothalamus and pituitary, which we tested by exposing male arctic ground squirrels to a warm ambient temperature (30°C) during midhibernation, which causes animals to prematurely end hibernation. However, the premature termination of hibernation resulted in limited ultrastructural changes, suggesting that temperature alone is insufficient to activate reproductive maturation. Altogether, our study reveals a previously underappreciated physiological dynamism during hibernation that allows animals to rapidly transition between seemingly incongruous life-history states.
    • A nonlethal, whole oocyte approach to determining spawn readiness in Pacific sand lance, Ammodytes personatus, in Southeastern Alaska

      Neff, A. Darcie; Norcross, Brenda L.; López, J. Andrés (2021-08)
      Knowing when a fish spawns is fundamental to understanding and sustainably managing it. The annual reproductive cycle of the iteroparous, total-spawning sand lances and sandeels (Ammodytidae) has been described almost exclusively using gonadal macroscopy and gonadosomatic indices (GSI), with little attention to gamete changes indicative of imminent ovulation and spawning. The latter was the focus of this study, in which spawn readiness of a southeastern Alaska population of Pacific sand lance (Ammodytes personatus) with unknown spawning phenology was assessed using light microscopy of whole oocytes. Oocytes were cannulated from spawning-capable females age-3 to age-9, measured for diameter, and classified into five developmental stages based on the coalescence of lipids and the position and integrity of the germinal vesicle. Oocyte maturation lasted 5-6 weeks, as determined by weekly cannulation of captive females. Diameter and developmental stage of oocytes were more precise metrics of readiness to spawn than macroscopy or GSI and indicated spawning in early- to mid-December. The examination of nonlethally collected whole oocytes is a quick, easy, and low-cost approach to the accurate and reliable assessment of spawn readiness in Pacific sand lance and offers the potential of success with congenerics and other total-spawning fish species.
    • Ocean and stream ecology of adult hatchery and wild pink salmon

      McMahon, Julia; Westley, Peter; Gorman, Kristen; McPhee, Megan; Rand, Peter (2021-08)
      In this thesis I investigate potential interactions of hatchery and wild pink salmon (Oncorhynchus gorbuscha) at sea and on the spawning grounds, in the context of the ecological and economic importance of modern Alaskan hatcheries. Although hatchery and wild salmon are known to interact, the nature and outcome of those interactions remain unclear. Here, I identify potential mechanisms of competition and hatchery salmon fitness with two datasets from Prince William Sound, Alaska, home to the largest pink salmon hatchery program in the world. First, I compared fitness-related traits such as body length, return timing, instream lifespan, and egg retention between straying hatchery and homing wild pink salmon to identify potential barriers or bridges to gene flow with over 120,000 individuals sampled over six years (2013-2018). Predicted lengths of hatchery and wild fish depended on the even or odd year lineage, return timing, and sex. Odd year pink salmon were smaller on average than even year pink salmon, odd year hatchery fish were smaller than wild fish, odd year length decreased over the season, and odd year males tended to be larger than females. In even years, hatchery pink salmon were larger on average than wild pink salmon, length increased over the season, and hatchery females were larger on average than any other group. I found no statistically significant differences in instream lifespan (2017: t-test (₂₀.₅₄), P = 0.41; 2018: t-test(₆.₂₆), P = 0.556) or egg retention (x²₍₂₎= 4.5, p = 0.11; 2017 and 2018 combined) between hatchery and wild fish. In contrast, I detected significant differences in stream life of the wild fish between two different sized streams in a manner consistent with observed black bear (Ursus americanus) predation; specifically stream life was shorter in the smaller stream with markedly higher predation. Second, I used stable carbon and nitrogen isotope analysis to test the hypothesis that hatchery and wild pink salmon have distinct foraging niches during their last months at sea, which could underpin observed differences in length between hatchery and wild pink salmon. Using data from 2015, I fit linear models and detected no difference in broad-scale foraging locations (delta¹³C values) of hatchery and wild pink salmon. However, trophic positions (delta¹⁵N values) for hatchery and wild pink salmon were inversely related to size where large wild salmon and small hatchery salmon tended to have the highest delta¹⁵N values. Because delta¹³C values and delta¹⁵N values of wild fish were positively associated with body size, it is likely that hatchery and wild pink salmon have size-dependent, yet still overlapping foraging niches. Overall, these results are consistent with the potential for hatchery and wild pink salmon to compete for resources on the spawning grounds and at sea to the extent that resources are limiting.