• Arctic fox winter movement and diet in relation to industrial development on Alaska's North Slope

      Lehner, Neil S.; Person, Brian; Kielland, Knut; O'Brien, Diane; Hunter, Christine (2012-12)
      I examined winter movement and diet of Arctic foxes (Vulpes lagopus) in the Prudhoe Bay oilfields and an adjacent undeveloped area (National Petroleum Reserve-Alaska (NPR-A)). Movement metrics were compared between these areas using data from satellite collars. Daily travel rate was approximately 5 times greater in the undeveloped area than in Prudhoe Bay. Four adult foxes collared in NPR-A used the sea ice for extensive time periods. One of these foxes traveled 338 km in three days while another traveled to Banks Island (Northwest Territories, Canada), over 1050 km from its capture location. Prudhoe Bay foxes did not make these long distance movements and remained near their summer capture location throughout winter. I used stable isotope analysis and a mixing model (SIAR) to estimate the contribution of marine, terrestrial, and anthropogenic foods to fox diet. Based on muscle tissue, the average contribution of anthropogenic foods to Prudhoe Bay fox diet was more that 50%. Marine foods were utilized in NPR-A, but not in Prudhoe Bay. Results demonstrate that anthropogenic foods are heavily utilized by foxes that overwinter in the oilfields and this food source is likely responsible for reduced winter movements of Prudhoe Bay foxes. Therefore, industrial development strongly affects winter movement and diet of foxes.
    • Common ravens in Alaska's North Slope oil fields: an integrated study using local knowledge and science

      Backensto, Stacia Ann (2010-05)
      Common ravens (Corvus corax) that nest on human structures in the Kuparuk and Prudhoe Bay oil fields on Alaska's North Slope are believed to present a predation risk to tundra-nesting birds in this area. In order to gain more information about the history of the resident raven population and their use of anthropogenic resources in the oil fields, I documented oil field worker knowledge of ravens in this area. In order to understand how anthropogenic subsidies in the oil fields affect the breeding population, I examined the influence of types of structures and food subsidies on raven nest site use and productivity in the oil fields. Oil field workers provided new and supplemental information about the breeding population. This work in conjunction with a scientific study of the breeding population suggests that structures in the oil fields were important to ravens throughout the year by providing nest sites and warm locations to roost during the winter. The breeding population was very successful and appears to be limited by suitable nest sites. The landfill is an important food source to ravens during winter, and pick-up trucks provide a supplemental source of food throughout the year. Further research will be necessary to identify how food (anthropogenic and natural) availability affects productivity and the degree to which ravens impact tundra-nesting birds.
    • Global and local contributors to the historical and projected regional climate change on the North Slope of Alaska

      Cai, Lei; Alexeev, Vladimir A.; Arp, Christopher D.; Bhatt, Uma S.; Liljedahl, Anna K. (2018-05)
      This thesis includes four studies that explore and compare the impacts of four contributing factors resulting in regional climate change on the North Slope of Alaska based on a numerical simulation approach. These four contributing factors include global warming due to changes in radiative forcing, sea ice decline, earlier Arctic lake ice-off, and atmospheric circulation change over the Arctic. A set of dynamically downscaled regional climate products has been developed for the North Slope of Alaska over the period from 1950 up to 2100. A fine grid spacing (10 km) is employed to develop products that resolve detailed mesoscale features in the temperature and precipitation fields on the North Slope of Alaska. Processes resolved include the effects of topography on regional climate and extreme precipitation events. The Representative Concentration Pathway (RCP) 4.5 scenario projects lower rates of precipitation and temperature increase than RCP8.5 compared to the historical product. The increases of precipitation and temperature trends in the RCP8.5 projection are higher in fall and winter compared to the historical product and the RCP4.5 projection. The impacts of sea ice decline are addressed by conducting sensitivity experiments employing both an atmospheric model and a permafrost model. The sea ice decline impacts are most pronounced in late fall and early winter. The near surface atmospheric warming in late spring and early summer due to sea ice decline are projected to be stronger in the 21st century. Such a warming effect also reduces the total cloud cover on the North Slope of Alaska in summer by destabilizing the atmospheric boundary layer. The sea ice decline warms the atmosphere and the permafrost on the North Slope of Alaska less strongly than the global warming does, while it primarily results in higher seasonal variability of the positive temperature trend that is bigger in late fall and early winter than in other seasons. The ongoing and projected earlier melt of the Arctic lake ice also contributes to regional climate change on the Northern coast of Alaska, though only on a local and seasonal scale. Heat and moisture released from the opened lake surface primarily propagate downwind of the lakes. The impacts of the earlier lake ice-off on both the atmosphere and the permafrost underneath are comparable to those of the sea ice decline in late spring and early summer, while they are roughly six times weaker than those of sea ice decline in late fall and early winter. The permafrost warming resulted from the earlier lake ice-off is speculated to be stronger with more snowfall expected in the 21st century, while the overall atmospheric warming of global origin is speculated to continue growing. Two major Arctic summer-time climatic variability patterns, the Arctic Oscillation (AO) and the Arctic Dipole (AD), are evaluated in 12 global climate models in Coupled Model Intercomparison Program Phase 5 (CMIP5). A combined metric ranking approach ranks the models by the Pattern Correlation Coefficients (PCCs) and explained variances calculated from the model-produced summer AO and AD over the historical period. Higher-ranked models more consistently project a positive trend of the summer AO index and a negative trend of summer AD index in their RCP8.5 projections. Such long-term trends of large-scale climate patterns will inhibit the increase in air temperature while favoring the increase in precipitation on the North Slope of Alaska. In summary, this thesis bridges the gaps by quantifying the relative importance of multiple contributing factors to the regional climate change on the North Slope of Alaska. Global warming is the leading contributing factor, while other factors primarily contribute to the spatial and temporal asymmetries of the regional climate change. The results of this thesis lead to a better understanding of the physical mechanisms behind the climatic impacts to the hydrological and ecological changes of the North Slope of Alaska that have been become more severe and more frequent. They, together with the developed downscaling data products, serve as the climatic background information in such fields of study.
    • Human-bear interactions in the North Slope oilfields of Alaska (USA): characteristics of grizzly bear sightings and use of infrared for bear den detection

      Pedersen, Nils J. S.; Brinkman, Todd J.; Shideler, Richard T.; Brainerd, Scott; Lindberg, Mark (2019-05)
      Minimizing unsafe human-bear (Ursus spp.) interactions in the North Slope oilfields of Alaska (USA) requires knowledge of where they occur and methods to prevent them. My research goals were to characterize the spatial and temporal dynamics of grizzly bear (U. arctos) sightings during the non-denning season around industrial infrastructure in the North Slope oilfields over the past 25 years (Chapter 2), and to evaluate the efficacy of forward-looking infrared (FLIR) systems to detect grizzly bears and polar bears (U. maritimus) in their winter dens (Chapter 3). I used reports (n = 2,453) of summer grizzly bear sightings collected by oilfield security officers from 1990-2014 to estimate how the spatial distribution of sightings for food-conditioned (FC) and natural food (NF) bears changed following restriction of bear access to anthropogenic food waste (to be known hereafter as "treatment") in 2001. I found that concentrations of FC bear sightings shifted toward the landfill with medium-low effect (Hedges' g = 0.41), one of the only remaining areas with available food waste, after the treatment. The treatment also decreased NF bear sighting distances to landfill with low effect (Hedges' g = 0.15). My findings suggested that grizzly bear access to food waste should be prevented to minimize negative human-bear interactions and that an active bear reporting system facilitates adaptive management of human-bear interactions. During the winter, grizzly bears and pregnant female polar bears enter dens in areas that overlap anthropogenic activity. FLIR techniques have been used to locate occupied dens by detecting heat emitted from denned bears. However, the effects of environmental conditions on den detection have not been rigorously evaluated. I used a FLIR-equipped Unmanned Aircraft System (UAS) to collect images of artificial polar bear (APD) and grizzly bear (AGD) dens from horizontal and vertical perspectives from December 2016 to April 2017 to assess how odds of detection changed relative to den characteristics and environmental conditions. I used logistic regression to estimate effects of 11 weather variables on odds of detection using 291 images. I found that UAS-FLIR detected APDs two times better than AGDs, vertical perspective detected 4 times better than horizontal, and that lower air temperatures and wind speeds, and the absence of precipitation and direct solar radiation increased odds of detection for APDs. An increase of 1°C air temperature lowered the odds of detection by 12% for APD, and 8% for AGDs, but physical den characteristics such as den snow wall thickness determined detectability of AGDs. UAS-FLIR surveys should be conducted on cold, clear days, with calm winds and minimal solar radiation, early in the denning season. UAS-FLIR detectionof bear dens can be effective but should be confirmed by a secondary method.
    • Petrographic and microfacies analysis of the Shublik formation, northern Alaska: implications for an unconventional resource system

      Knox, April Rae; Whalen, Michael; Hanks, Catherine; Wartes, Marwan (2018-08)
      The North Slope of Alaska includes a world-class conventional petroleum system that has been producing for approximately 40 years. While the regional stratigraphy includes multiple proven source and reservoir rocks, the Middle to Upper Triassic Shublik Formation (Fm.) is the most prolific. The decline in conventional hydrocarbon production on the North Slope and the presence of high quality source rocks inspire the evaluation of the Shublik Fm. as an unconventional petroleum system where oil or gas are produced directly from source rocks. The Shublik Fm. is a heterogeneous calcareous shale and limestone interval that has been interpreted to indicate deposition influenced by marine upwelling. Lithofacies observed in outcrop consist of intervals of non-resistant organic-rich packages that are interbedded with resistant coarsening upward rhythmic depositional successions of phosphatic and carbonate parasequences. The heterogenous characteristics of the microfacies is one of the challenges in the unconventional exploration of the Shublik Fm. Detailed microfacies descriptions, as part of this study, document the complex lithologies and identify patterns in the occurrence of the microfacies. Microfacies descriptions are the building blocks to identify stacking patterns that define the parasequences. The parasequences observed in core, outcrop, and petrographic analysis are calibrated to well logs to map relevant stratigraphic intervals on a regional scale. A targeted interval for the unconventional exploration of the Shublik Fm. is identified using a relative brittleness index. Flat clam and phosphatic parasequences are the primary packages present within the targeted interval. The parasequences are comprised of small-scale brittle and ductile couplets. High resolution pore imaging and mechanical stratigraphy characteristics are documented within the interval. Pore types and networks provide potential storage and migration pathways within unconventional resource systems. Pore types were imaged at a high resolution using scanning electron microscopy. Pore types that are present within the Shublik Fm. include interparticle, intraparticle, porous floccules, moldic, microfracture, and microchannel. The phosphatic limestone facies contains the greatest amount of porosity including interparticle, intraparticle, and moldic within the phosphate nodules and matrix and fractures surrounding phosphate nodules. Microfracture, microchannel, and intraparticle porosity are the primary pore types within the flat clam facies. Mechanical stratigraphy has a direct impact on the success of hydraulic fracturing. The microfacies descriptions identify laminae scale mechanical stratigraphy characteristics which include erosional surfaces, laminations, graded bedding, mineralogical variation, and textural anisotropy and isotropy. A regional correlation of the targeted interval was developed building upon previous work and utilizing sequence stratigraphic models. Significant parasequence surfaces are readily identified in the well log signatures. The challenge of the heterogeneity of the Shublik Fm. is simplified first by identifying a targeted interval consisting of brittle and ductile packages enriched in TOC. Then recognizing the parasequences contained as part of the interval which include significant characteristics pertaining to pore networks and mechanical stratigraphy. Combining methods and results of this study provides an important component to evaluating the Shublik Fm. as a potential unconventional resource system.
    • Processes controlling thermokarst lake expansion rates on the Arctic coastal plain of Northern Alaska

      Bondurant, Allen C.; Arp, Christopher D.; Jones, Benjamin M.; Daanen, Ronald P.; Shur, Yuri L. (2017-08)
      Thermokarst lakes are a dominant factor of landscape scale processes and permafrost dynamics in the otherwise continuous permafrost region of the Arctic Coastal Plain (ACP) of northern Alaska. Lakes cover greater than 20% of the landscape on the ACP and drained lake basins cover an additional 50 to 60% of the landscape. The formation, expansion, drainage, and reformation of thermokarst lakes has been described by some researchers as part of a natural cycle, the thaw lake cycle, that has reworked the ACP landscape during the course of the Holocene. Yet the factors and processes controlling contemporary thermokarst lake expansion remain poorly described. This thesis focuses on the factors controlling variation in extant thermokarst lake expansion rates in three ACP regions that vary with respect to landscape history, ground-ice content, and lake characteristics (i.e. size and depth). Through the use of historical aerial imagery, satellite imagery, and field-based data collection, this study identifies the controlling factors at multiple spatial and temporal scales to better understand the processes relating to thermokarst lake expansion. Comparison of 35 lakes across the ACP shows regional differences in expansion rate related to permafrost ice content ranging from an average expansion rate of 0.62 m/yr on the Younger Outer Coastal Plain where ice content is highest to 0.16 m/yr on the Inner Coastal Plain where ice content is lowest. Within each region, lakes vary in their expansion rates due to factors such as lake size, lake depth, and winter ice regime. On an individual level, lakes vary due to shoreline characteristics such as local bathymetry and bluff height. Predicting how thermokarst lakes will behave locally and on a landscape scale is increasingly important for managing habitat and water resources and informing models of land-climate interactions in the Arctic.
    • Social-ecological soundscapes: examining aircraft-harvester-caribou conflict in Arctic Alaska

      Stinchcomb, Taylor R.; Brinkman, Todd J.; Hundertmark, Kris; Fritz, Stacey A. (2017-12)
      As human development expands across the Arctic, it is crucial to carefully assess the impacts to remote natural ecosystems and to indigenous communities that rely on wild resources for nutritional and cultural wellbeing. Because indigenous communities and wildlife populations are interdependent, assessing how human activities impact traditional harvest practices can advance our understanding of the human dimensions of wildlife management. Indigenous communities across Arctic Alaska have expressed concern over the last four decades that low-flying aircraft interfere with their traditional harvest practices. For example, communities often have testified that aircraft disturb caribou (Rangifer tarandus) and thereby reduce harvest opportunities. Despite this longstanding concern, little research exists on the extent of aircraft activity in Arctic Alaska and on how aircraft affect the behavior and perceptions of harvesters. Therefore, the overarching goal of my research was to highlight the importance of aircraft-harvester conflict in Arctic Alaska and begin to address the issue using a scientific and community-driven approach. In Chapter 1, I demonstrated that conflict between aircraft and indigenous harvesters in Arctic Alaska is a widespread, understudied, and complex issue. By conducting a meta-analysis of the available literature, I quantified the deficiency of scientific knowledge about the impacts of aircraft on rural communities and traditional harvest practices in the Arctic. My results indicated that no peer-reviewed literature has addressed the conflict between low-flying aircraft and traditional harvesters in Arctic Alaska. I speculated that the scale over which aircraft, rural communities, and wildlife interact limits scientists' ability to determine causal relationships and therefore detracts from their interest in researching the human dimension of this social-ecological system. Innovative research approaches like soundscape ecology could begin to quantify interactions and provide baseline data that may foster mitigation discourses among stakeholders. In Chapter 2, I employed a soundscape-ecology approach to address concerns about aircraft activity expressed by the Alaska Native community of Nuiqsut. Nuiqsut faces the greatest volume of aircraft activity of any community in Arctic Alaska because of its proximity to intensive oil and gas activity. However, information on when and where these aircraft are flying is unavailable to residents, managers, and researchers. I worked closely with Nuiqsut residents to deploy acoustic monitoring systems along important caribou harvest corridors during the peak of caribou harvest, from early June through late August 2016. This method successfully captured aircraft sound and the community embraced my science for addressing local priorities. I found aircraft activity levels near Nuiqsut and surrounding oil developments (12 daily events) to be approximately six times greater than in areas over 30 km from the village (two daily events). Aircraft sound disturbance was 26 times lower in undeveloped areas (Noise Free Interval =13 hrs) than near human development (NFI = 0.5 hrs). My study provided baseline data on aircraft activity and noise levels. My research could be used by stakeholders and managers to develop conflict avoidance agreements and minimize interference with traditional harvest practices. Soundscape methods could be adapted to rural regions across Alaska that may be experiencing conflict with aircraft or other sources of noise that disrupt human-wildlife interactions. By quantifying aircraft activity using a soundscape approach, I demonstrated a novel application of an emerging field in ecology and provided the first scientific data on one dimension of a larger social-ecological system. Future soundscape studies should be integrated with research on both harvester and caribou behaviors to understand how the components within this system are interacting over space and time. Understanding the long-term impacts to traditional harvest practices will require integrated, cross-disciplinary efforts that collaborate with communities and other relevant stakeholders. Finally, my research will likely spark efforts to monitor and mitigate aircraft impacts to wildlife populations and traditional harvest practices across Alaska, helping to inform a decision-making process currently hindered by an absence of objective data.