• Winter foraging ecology of moose in the Tanana Flats and Alaska Range foothills

      Seaton, C. Tom (2002-12)
      I studied woody browse distribution, production, removal, species composition, twig size, moose diets, and predicted daily intake of resident and migratory moose in the Tanana Flats and adjacent Alaska Range Foothills, Alaska, 1999-2000. Density of moose in these areas was high (1.1 moose/km²). Moose were experiencing density-dependent effects on reproduction and growth, exhibited by low adult twinning rate (6%) and absence of pregnant yearlings, yet 17.5 kg higher 10-month-old calf body weights in the migratory segment. Of all willow, poplar, and paper birch plants sampled, 74% had a broomed architecture, which I attributed to heavy use by moose. Using a model of daily moose intake based on bite mass and bite density, I estimated that 1) migratory moose met expected intake during winter while intake of resident moose was marginal, 2) moose could not meet their expected daily intake with the mean twig dry mass (0.26 g) remaining unbrowsed at end of winter, and 3) higher predicted intake by migratory moose than resident moose was consistent with their higher 10-month-old calf weights.
    • Winter movements of Arctic foxes in Northern Alaska measured by satellite telemetry

      Pamperin, Nathan J.; Follman, Erich H.; Lindberg, Mark S.; Huettmann, Falk; Person, Brian (2008-12)
      We studied winter movements of 37 arctic foxes (Alopex lagopus) collared within a petroleum development area at Prudhoe Bay, Alaska (n = 20), and an undeveloped area in the National Petroleum Reserve-Alaska (NPR-A, n = 17) during the winters of 2004, 2005, and 2006 using satellite telemetry. Comparing Prudhoe Bay and NPR-A, differences in mean movement rates of juveniles was 23.9 ± 2.7 km per duty cycle and 10.6 ± 2.8 km per duty cycle for adults, and mean difference in maximum distance from capture site for juveniles was 265.2 ± 63.2 km and 205.5 ± 128.9 km for adults. Juveniles and adults collared in NPR-A were highly mobile and made long distance movements (up to 782 km) while foxes from Prudhoe Bay remained in or near the oil field throughout winter. Extensive use of sea-ice by three juvenile foxes from NPR-A was documented during the winter of 2005-2006. Three juvenile foxes traveled long distances (904, 1096, and 2757 km) during the winter and remained on the sea-ice for extended periods of time (76, 120, and 156 days). These findings verify the use of sea-ice by arctic foxes and raise concerns that the diminishing ice cover may negatively impact populations by limiting access to marine food sources. We conclude that the oilfields are having a strong effect on the winter movements of arctic fox and suggest differences in movements are likely attributable to the availability of anthropogenic foods at Prudhoe Bay.
    • Winter Range Studies Of The Western Arctic Caribou Herd, Northwest Alaska

      Joly, Kyle; Chapin, F.S.; Rupp, T.S.; Klein, David R.; Verbyla, David L. (2011)
      Climate change is likely to bring a myriad of interrelated changes to the Arctic. One change is warmer and drier conditions that could increase the prevalence of wildfire in northwest Alaska. Wildfires destroy terricolous lichens that Western Arctic Herd caribou (Rangifer tarandus ) rely on during winter; taking decades to recover. My goals were to assess the recent (1950--2007) fire regime within the herd's range, identify characteristics of habitat selected by overwintering caribou, and determine the potential impacts of climate change on the fire regime and caribou winter range. I used a combination of existing data and information collected at vegetation plots to conduct these analyses. I found that wildfires in the tundra were relatively common from 1950--2007, covering approximately 10% of northwest Alaska. Tundra was > 4.5 times more likely to re-burn than boreal forest. This novel, yet intuitive finding could have serious implications if fire starts to become more common in the Arctic. I found that the average annual area burned more than doubled in years where mean August temperatures exceeded 11.7�C (53�F). Caribou use tundra and forested during winter but avoided recently (< 58 years) burned areas in both habitat types likely because they contained < 1/4 of the abundance of forage lichen species than unburned habitats. I found that lichen abundance was 3 times greater in the herd's current winter range versus its historic range -- supporting the theory that caribou shift ranges to compensate for deteriorating grazing conditions. Stand age was the most consistent correlate with lichen abundance. Dwarf birch (Betula spp.) was more abundant in recent burns which may facilitate the intensification of the future fire regime in the region. My modeling efforts revealed that wildfire is likely to become more prevalent, especially on the herd's core winter range, which could have deleterious impacts on caribou winter range and provide quality habitat for moose ( Alces alces). My results should provide a solid foundation to develop a science-based fire management plan for the Western Arctic Herd.
    • Winter vertebrate browsing of birch: effects on the use of leaf litter leachates by stream microorganisms

      Estensen, Jeffrey L. (2001-05)
      Winter browsing of birch leads to chemical changes in leaves of the following growing season, potentially generating differences in the quality of leachates derived from leaf litter and in leachate use by stream microorganisms. The effects of moose browsing were tested on leachates from leaves collected from browsed and unbrowsed trees and inoculated with microbial communities. Respiration and bacterial abundance were used to assess qualitative differences in leachates. Microbes cultured in leachates derived from leaves of browsed trees had significantly higher rates of oxygen uptake. There were no significant differences in bacterial abundance between treatments. The basis for the qualitative difference in leachates is likely due to an 89% greater concentration of amino acides in leachates derived from leaves of previously browsed trees. This study provides evidence that winter herbivory of birch can influence the use of leaf leachates by stream microbes, demonstrating coupling between riparian zones and stream ecosystems.
    • Wintering strategies of an Arctic-nesting goose: costs of migration and over-wintering for Pacific black brant

      Mather, Danielle D. (2005-05)
      Birds wintering in different climates may have different strategies for storing and using energy. We documented changes in body morphology and composition of Pacific Black Brant (Branta bernicla nigricans) wintering in Alaska and Baja California and modeled the energetic costs of wintering at each location. We compared costs associated with two different wintering strategies: 1) to remain in an unstable and harsh environment but close to breeding grounds, or 2) to migrate long distances to a mild environment, but distant from breeding grounds. Despite dramatic differences in the timing and magnitude of energetic costs between sites, Brant stored similar amounts of lipid and maintained similar body mass throughout winter. Brant operate under similar physiological bounds but changes in organ mass and nutrient storage took place within these bounds. This flexibility allowed Brant to employ two contrasting winter strategies. We suggest that there may be reproductive and energetic advantages associated with shortening migration distance and remaining in Alaska over winter. The number of Brant wintering in Alaska should continue to increase if constraints on food intake do not impede energy storage and survival is similar between sites.
    • X-ray fluorescence spectrometry using synchrotron radiation with applications in unmanned aircraft environmental sensing

      Barberie, Sean Richard Gopal; Cahill, Catherine F.; Hatfield, Michael C.; Iceman, Christopher R. (2015-12)
      In this thesis I present an analytical optimization of the Synchrotron Radiation X-Ray Fluorescence (SR-XRF) technique for applications in unmanned aircraft aerosol studies. In environmental and atmospheric science, there is a pressing need for aerosol measurements at various altitudes in the atmosphere and spanning large regions. This need is currently either ignored, or met to a limited degree by studies that employ manned aircraft. There is, however, a great deal of opportunity to improve and expand on these studies using the emerging technology of unmanned aircraft systems. A newly developed aerosol sampler makes this opportunity a near-reality by its ability to collect aerosol samples in-situ from unmanned aircraft platforms. The challenge lies in analyzing these samples for elemental composition. In airborne aerosol studies, the ability to resolve where a sample was collected both spatially and temporally is limited by the sensitivity of the analysis technique. In aircraft-based aerosol collection, the length of the aerosol sample spot corresponds to distance. Thus the spatial resolution of an airborne study is limited by the amount of mass that must be collected for analysis. The SR-XRF optimizations outlined in this thesis decrease the amount of sample mass required for detectable elemental concentrations, allowing aerosol samples to be analyzed in smaller areas corresponding to smaller time steps. Since, in a flight path, time steps are directly correlated with distance, analysis of smaller time steps results in the ability to measure aerosols at higher spatial resolution. Four SR-XRF analysis configurations were experimentally tested: monochromatic beam, white beam, filtered white beam, and filtered white beam-filtered detector to determine which configuration gave the highest elemental sensitivity and selectivity. Of these tested methods, the straight polychromatic white beam configuration resulted in the best sensitivity for elements across a large range of x-ray energies for small amounts of mass collected on thin film substrates. The research in this thesis provides researchers with an optimized method for non-destructively analyzing a wide variety of environmental samples with high elemental sensitivity and selectivity. This research also has important implications for the ability to perform in-situ aerosol studies with unmanned aircraft on a systematic basis.
    • Zinc oxide nanoparticles and SH-SY5Y cell line

      Zheng, Jinghui; 郑, 静慧; Duffy, Lawrence; Dunlap, Kriya; Drew, Kelly; Das, Debendra (2013-08)
      The Arctic and sub-arctic regions are impacted by the growth of the global nanotechnology industry. Nanomaterials have unique chemical and physical properties that may lead to toxicological effects that interfere with normal cellular metabolism. Zinc oxide nanoparticles (ZnO NPs) are now very common and widely used in daily life. In industry, ZnO NPs are used to protect different materials from damage caused by UV exposure. The scientific literature suggests that ZnO NPs can have negative impacts on both living organisms and plants. However, there is a paucity of research on the mechanisms by which ZnO NPs may affect the neuronal cells. This study investigates how ZnO NPs interact with the neuroblastoma cell line SH-SY5Y. Using transmission electron microscopy, we observed that the ZnO NPs form 36 nm particles on average, and increase the level of vascular endothelial growth factor (VEGF) in extracellular fluid, as measured by an enzyme-linked immunosorbent assay (ELISA). Moreover, ZnO NPs, in presence of tumor neucrosis factor- α (TNF-α), can also decrease the level of extracellular VEGF compared with TNF-a treatment alone. These findings suggest the basis for more studies on understanding the mechanism by which ZnO NPs impact cytokine signaling. Another direction is using ELISA technology to observe the interactions of NPs with different cell types such as neuronal stem cells.