• Population status and patterns of distribution and productivity of kittiwakes on St. George Island, Alaska

      Kildaw, Stewart Dean (1998)
      I studied populations, distributions, and reproductive performance of red-legged and black-legged kittiwakes on St. George Island in the summers of 1993-1995, where populations of both species have experienced generally poor reproductive performance and population declines of ca. 40% over the past 20 years. In 1995, I conducted a whole-island census of kittiwakes on St. George Island and found estimated breeding populations of 193,930 red-legged kittiwakes (81% of their global population), and 62,568 black-legged kittiwakes. In addition, I analyzed census trends on 51 land-based census plots on St. George Island and found that numbers of both species have stabilized in recent years. I experimentally evaluated the hypothesis that nesting red-legged kittiwakes on St. George Island are competitively displaced by larger-bodied black-legged kittiwakes to narrower rock ledges and higher elevations. I determined nest-site preferences of both species by attaching narrow and wide artificial nesting ledges within high-and low-elevation areas of St. George Island and found no evidence of competitive displacement: red-legged kittiwakes preferred narrow ledges, black-legged kittiwakes preferred wide ledges, and both species preferred ledges in areas where conspecifics nested at high density. Multiple regression analyses suggested that kittiwakes breed earlier and more successfully in summers preceded by cold winters and that inter-annual variability in kittiwake breeding success was unrelated to weather conditions during the breeding season itself. These results suggest that winter weather has indirect effects on breeding kittiwakes by influencing prey abundance several months later. Furthermore, strong winds impaired growth rates of kittiwake chicks in exposed nest sites and the growth of black-legged kittiwake chicks relative to red-legged kittiwake chicks. I identified two prominent patterns of within-colony spatial variability in kittiwake productivity and suggest that patchy "bird quality" or localized "information neighborhoods" may be responsible because traditional explanations do not apply. The "information neighborhood" is a new hypothesis which proposes that individuals are influenced by the breeding status of neighbors because their status represents an additional source of information about current breeding conditions that can be used to better tailor parental investment.
    • Population Structure And Hybridization Of Alaskan Caribou And Reindeer: Integrating Genetics And Local Knowledge

      Mager, Karen H.; Hundertmark, Kris J.; Chapin, F. Stuart III; Kielland, Knut; Schneider, William S. (2012)
      Alaskan caribou (Rangifer tarandus granti) are a valued game species and a key grazer in Alaska's terrestrial ecosystem. Caribou herds, defined by female fidelity to calving grounds, are management units. However, the extent to which herds constitute genetic populations is unknown. Historical fluctuations in herd size, range, and distribution suggest periods of contact and isolation between herds. Likewise, historical contact between caribou and introduced domestic reindeer (R.t. tarandus) created opportunities for hybridization, but its extent is not known. I conducted an interdisciplinary study to understand how historical processes influence genetic identity and population structure of caribou and reindeer. Interviews with herders and hunters in Barrow, Alaska, revealed that many reindeer migrated away with caribou in the 1940s despite herder efforts to prevent mixing. Local observations of reindeer-like animals in caribou herds today suggest feral reindeer may survive and interbreed. Using genetic analysis of North Slope caribou and Seward Peninsula reindeer (n = 312) at 19 microsatellite loci, I detected individuals with hybrid ancestry in all four caribou herds and in reindeer. Selective hunting of reindeer-like animals, along with herd size and natural selection, may remove reindeer from caribou herds over time. I used genetics as well to describe caribou population structure and determine how it is influenced by geography, historical demography, and ecotypes. I found that Alaskan caribou from 20 herds (n = 655) are subdivided into two genetic clusters: the Alaska Peninsula and the mainland. Alaska Peninsula herds are genetically distinct, while many mainland herds are not. I hypothesize that Alaska Peninsula herds have diverged due to post-glacial founder effects and recent bottlenecks driven by constraints to population size from marginal habitat and reduced gene flow across a habitat barrier at the nexus of the peninsula. I hypothesize that mainland herds have maintained genetic connectivity and large effective population size via range expansions and shifts over time. However, I find evidence that herds of different ecotypes (migratory, sedentary) can remain differentiated despite range overlap. Genetic evidence provides information for herd-based management, while also demonstrating the importance of spatial connectivity of herds and their habitats over the long-term.
    • Post eruptive source modeling for Okmok Volcano, Alaska using GPS and InSAR

      Miller, Summer A.; Freymueller, Jeffrey; Meyer, Franz; Atwood, Don (2014-12)
      Okmok volcano is one of the most active volcanoes in the Aleutian Island chain, showing significant non-linear deformation as it progresses through eruption cycles. Okmok most recently erupted in July 2008, creating a new cone (~250m in height) and greatly changing the topography inside the caldera. Due to these changes within the caldera and magma system, new modeling of the volcanic source was completed. This study compiles both GPS and SAR measurements to constrain the post eruptive behavior, examines the possible changes below the surface, and explores modeling and optimization techniques. With continuous and campaign GPS stations and L-band radar imagery from the JAXA ALOS PALSAR satellite spanning August 2008 to October 2010, a variety of source models were tested and a best fit source model for the post eruptive behavior was found. Previously, a simple Mogi model was used in describing the behavior seen at Okmok, but post eruptive analysis showed a Double Mogi source for the initial first year of refilling. A 2 Mogi model did provide a better fit for the second year of deformation, but residual features due to compaction and erosion may have affected the modeling. These multiple Mogi models should be tested in future studies at Okmok and other shallow magma systems.
    • Post-caldera eruptions at Okmok Volcano, Umnak Island, Alaska, with emphasis on recent eruptions from cone A

      Grey, Delenora M. (2003-12)
      Okmok volcano has undergone two caldera-forming eruptions, 12,000 and 2050 BP, and has been quite active in historic time. The historic eruptive record has been compiled and augmented with descriptions and photographs of recent eruptions. Eruptions in 1958 and 1997 produced the first post-caldera lava flows to traverse most of the caldera floor. The source of these flows, Cone A, has been constructed largely during the 20th century. Major element analysis of lavas from eight major intracaldera cones reveals two chemically and spatially separate trends, which suggest two separate magma sources beneath the caldera, one feeding an arc of cones extending from the west to north margin of the caldera, the other feeding an arc running from southwest to east. Recent geodetic results by other workers show a single active inflation source related to Cone A but located beneath the center of the caldera. A rheologic study of the 1997 lava flow was undertaken to determine how viscosities calculated from flow morphology compare with viscosities and eruption temperatures obtained from petrology. This may be a useful tool for constraining composition of new flows observed by satellite imagery, and for constraining eruptive conditions for older flows when chemistry is known.
    • Post-fire variability in Siberian alder in Interior Alaska: distribution patterns, nitrogen fixation rates, and ecosystem consequences

      Houseman, Brian Richard; Ruess, Roger; Hollingsworth, Teresa; Verbyla, Dave (2017-12)
      The circumpolar boreal forest is responsible for a considerable proportion of global carbon sequestration and is an ecosystem with limited nitrogen (N) pools. Boreal forest fires are predicted to increase in severity, size, and frequency resulting in increased losses of N from this system due to volatilization. Siberian alder (Alnus viridis ssp. fruticosa) N-fixation is a significant source of N-input within the interior Alaskan boreal forest and likely plays a pivotal, though poorly understood, role in offsetting losses of N due to fire. This study disentangles the effects of fire severity, post-fire age, and environmental variables on Siberian alder N-input across the upland boreal forest and quantifies the landscape-level implications of Siberian alder N-input on N pool balance. Stand types of an early- and intermediate-age burn scar were determined by relevé plot sampling, hierarchical clustering, and indicator species analysis. Alder growth traits (density, nodule biomass, nodule N-fixation, and other traits) were sampled across all stand types, burn scars, and a fire severity gradient. Pre- and post-fire landscape-level N-fixation inputs were quantified within the early-age burn scar by scaling-up Siberian alder growth traits to the stand-level and then mapping the total area of pre- and post-fire stand types. Results show that fire severity shares a complex relationship with Siberian alder N-input in black spruce stands, wherein moderate fire severity has a negligible effect on Siberian alder N-input, moderate to high fire severity increases Siberian alder N-input, and high fire severity reduces Siberian alder N-input. Fire likely limited alder vegetative propagation in post-fire black spruce trajectory stands but enhanced propagation in post-fire deciduous trajectory stands that experienced moderate severity. Following the 2004 Boundary Fire, Siberian alder N-input showed an overall increase across the landscape, mostly within post-fire deciduous stand types. Future increases of fire severity and subsequent conversions of stand type from black spruce to deciduous dominance have the potential to increase total short-term N-input on the landscape, but a majority of those gains will be concentrated within a small proportion of the post-fire landscape (i.e. deciduous trajectory stand types). In the boreal forest, the temporal and spatial pattern of ecosystem processes that rely on N fixation inputs is dependent on the recruitment and growth of Siberian alder, which is in turn dependent on a complex relationship between fire severity, stand type, and post-fire age.
    • Postbreeding Ecology Of Shorebirds On The Arctic Coastal Plain Of Alaska

      Taylor, Audrey R.; Powell, Abby N.; Lanctot, R. B.; Huettmann, F.; Kitaysky, A. S.; Williams, T. D. (2011)
      Previous research on the Arctic Coastal Plain (ACP) of Alaska has shown that postbreeding shorebirds congregate at coastal sites prior to fall migration. Relatively little has been done to compare distribution, community characteristics, or behavior broadly across the ACP landscape, but this information is necessary to set the context for interpreting population demographics and setting conservation priorities. I collected data on distribution, species composition, phenology, and habitat use of postbreeding shorebirds in 2005--2007. I found that distribution of shorebirds across the ACP was not uniform: I identified persistent "hotspots" at Peard Bay, Pt. Barrow/Elson Lagoon, Cape Simpson, Smith Bay to Cape Halkett, and at the Sagavanirktok and Kongakut Deltas. Staging phenology varied by species and location, and differed than that reported in previous studies for several species. Three foraging habitat guilds existed with birds favoring gravel beach, mudflat, or salt marsh/pond edge habitats. Using VHF telemetry. I examined how shorebirds moved from tundra breeding sites to and between coastal postbreeding sites. I found that most species exhibited a variable direction of movement compared to their ultimate migration direction; this may be related to each species' overall length of stay on the ACP. I also found species-specific patterns of movements and residence time that were indicative of differing life history strategies. Lastly, I examined the use of physiological tools (triglyceride and corticosterone levels) to assess function and quality of foraging sites for postbreeding shorebirds, taking into account varying molt strategies. I determined that molt strategies affected physiological profiles and physiologic metrics varied through space and time. However, my hypotheses for variation in physiological patterns for shorebirds employing different molt strategies and using sites of varying quality were not completely upheld. I suggest that assessments of site quality for postbreeding shorebirds should consider species-specific life history strategies, and use multiple species and physiological metrics as indicators. Given suspected declines in North American shorebird populations, and accelerated rates of environmental change in northern Alaska, this contextual information regarding postbreeding distribution, population characteristics, behavior, and physiology may help interpret changes in shorebird populations or behavior and establish strategies to protect important habitat.
    • Potential muskox habitat in the National Petroleum Reserve-Alaska: a GIS analysis

      Danks, Fiona Susan (2000-08)
      Muskoxen (Ovibos moschatus), reestablished in northern Alaska in recent decades, have been increasing in number and distribution. However, their selection of habitat within the landscape, historically and presently, remains inadequately documented. This project produced maps of predicted muskox habitat in the National Petroleum Reserve-Alaska (NPR-A), that provide a basis for management of muskoxen and protection of their habitat in relation to proposed oil, gas and mineral exploration. Vegetation analyses showed compositional differences and interactions between vegetation and terrain. Within a geographical information systems (GIS) database, muskox locations, satellite-based vegetation maps and terrain data for the Kuparuk River drainage basin were assimilated, and a maximum likelihood classification developed to produce a habitat selection model incorporating the interactive effects of these characteristics. Using NPR-A GIS data, the model was extrapolated to produce maps showing suitable summer habitat in lower-lying drainages and wetter areas, and suitable winter habitat in drier, more rugged, exposed areas.
    • Predatory Hymenopteran assemblages in boreal Alaska: associations with forest composition and post-fire succession

      Wenninger, Alexandria; Wagner, Diane; Hollingsworth, Teresa; Skies, Derek (2018-05)
      Predatory Hymenoptera play key roles in terrestrial foodwebs and affect ecosystem processes, but their assemblage composition and distribution among forest habitats are poorly understood. Historically, the boreal forest of interior Alaska has been characterized by a fire disturbance regime that maintains vegetation composition dominated by black spruce forest. Climate-driven changes in the boreal fire regime have begun to increase the occurrence of hardwood species in the boreal forest, including trembling aspen and Alaska paper birch. Replacement of black spruce forests with aspen forests may influence predatory hymenopteran assemblages due to differences in prey availability and extrafloral nectar provisioning. Furthermore, changes in the frequency and extent of boreal forest fires increase the proportion of forests in earlier successional stages, altering habitat structure. The primary goal of this study was to characterize predatory hymenopteran assemblages in post-fire boreal forests of interior Alaska. To investigate this, the abundance, species richness, and composition of predatory hymenopteran assemblages were compared among forests at different stages of succession that were dominated by black spruce pre-fire, but that vary in their tree species composition post-fire. Predatory hymenopterans were separated into three groups: ants, macropterous wasps, and micropterous wasps. Ant species richness and abundance were not related to forest composition, but both were significantly higher in early-successional forests than in mid-late successional forests. In contrast, macropterous wasp morphospecies richness and abundance, as well as micropterous wasp abundance, were positively related to the basal area of aspen, suggesting that aspen forests benefit macropterous and micropterous wasps, perhaps due to extrafloral nectar provisioning and the availability of greater quality prey than is provided by black spruce. Wasp assemblages did not differ between successional stages. This study is the first to characterize the influence of post-fire succession on predatory hymenopteran assemblages of the boreal forest at a large spatial scale. The results suggest that continued warming of the boreal forest will have cascading influences on the insect assemblages of boreal Alaska.
    • Predictive modeling of Alaskan brown bears (Ursus arctos): assessing future climate impacts with open access online software

      Henkelmann, Antje (2011-02-21)
      As vital representative indicators of the state of the ecosystem, Alaskan brown bear (Ursus arctos) populations have been studied extensively. However, an updated statewide density estimate is still absent, as are models predicting future occurrence and abundance. This kind of information is crucial to ensure population viability by adapting conservation planning to future needs. In this study, a predictive model for brown bear densities in Alaska was developed based on brown bear estimates derived on the best publicly available data (Miller et al. 1997). Salford’s TreeNet data mining software was applied to determine the impact of different environmental variables on bear density and for the first state-wide GIS prediction map for Alaska. The results emphasize the importance of ecoregions, climatic factors in December, human influence and food availability such as salmon. In order to assess the influence of changing climate conditions on brown bear populations, two different IPCC scenarios (A1B and A2) were applied to establish different predictive climate models. The results of these projections indicate a large expansion of brown bear densities within the next 100 years. High density habitat would thus expand from southern coastal areas towards central Alaska. Based on the modeling results, optimum potential protected areas were determined by means of the program Marxan. According to the outcome, the protection of brown bear populations and bear habitat should accordingly focus on areas along the southern coast of Alaska. The study provides a first digital GIS modeling infrastructure for bear densities in Alaska. Through the pro-active temporal and spatial identification of important brown bear habitats and connectivity zones ahead of time, measures ranging from conservation to the planning of transport facilities could be more effectively focused on minimizing and mitigating impacts to these critical areas before real-world problems occur, as well as in an Adaptive Sustainability Management framework.
    • Predictive Modeling of Avian Influenza in Wild Birds

      Herrick, Keiko; Huettmann, Falk; Taylor, Barbara; Runstadler, Jonathan; Ickert-Bond, Stephanie; Bortz, Eric (Veterinary Research, 2013-05)
      Over the past 20 years, highly pathogenic avian influenza (HPAI), specifically Eurasian H5N1 subtypes, caused economic losses to the poultry industry and sparked fears of a human influenza pandemic. Avian influenza virus (AIV) is widespread in wild bird populations in the low-pathogenicity form (LPAI), and wild birds are thought to be the reservoir for AIV. To date, however, nearly all predictive models of AIV focus on domestic poultry and HPAI H5N1 at a small country or regional scale. Clearly, there is a need and an opportunity to explore AIV in wild birds using data-mining and machinelearning techniques. I developed predictive models using the Random Forests algorithm to describe the ecological niche of avian influenza in wild birds. In “Chapter 2 - Predictive risk modeling of avian influenza around the Pacific Rim”, I demonstrated that it was possible to separate an AIV-positivity signal from general surveillance effort. Cold winters, high temperature seasonality, and a long distance from coast were important predictors. In “Chapter 3 - A global model of avian influenza prediction in wild birds: the importance of northern regions”, northern regions remained areas of high predicted occurrence even when using a global dataset of AIV. In surveillance data, the percentage of AIV-positive samples is typically very low, which can hamper machine-learning. For “Chapter 4 - Modeling avian influenza with Random Forests: under-sampling and model selection for unbalanced prevalence in surveillance data” I wrote custom code in R statistical programming language to evaluate a balancing algorithm, a model selection algorithm, and an under-sampling method for their effects on model accuracy. Repeated random iv sub-sampling was found to be the most reliable way to improved unbalanced datasets. In these models cold regions consistently bore the highest relative predicted occurrence scores for AIV-positivity and describe a niche for LPAI that is distinct from the niche for HPAI in domestic poultry. These studies represent a novel, initial attempt at constructing models for LPAI in wild birds and demonstrated high predictive power.
    • Prefledging survival and reproductive strategies in black brant

      Flint, Paul Leroy; Sedinger, James S. (1993)
      We develop a general model useful for estimating survival of young waterfowl between hatching and fledging. Our model allows for interchange of individuals among broods and relaxes the assumption that individuals within broods have independent survival probabilities. We consider point estimation of survival rates and corresponding variances of the point estimators. We estimated gosling survival of black brant (Branta bernicla nigricans) during summers of 1987-89 on the Yukon-Kuskokwim Delta, Alaska. Eight-two percent of females radio-marked at hatch fledged at least 1 gosling (brood success). Survival of goslings within broods was estimated by 3 methods: (1) changes in mean brood size through time, (2) observation of goslings associated with marked adults, and (3) age ratios of brant captured in banding drives. Estimates of survival within successful broods averaged 77% and ranged from 57 to 90%. Combining brood success and survival of young within broods yields estimates of overall gosling survival which averaged 64% and ranged from 77% in 1987 to 52% in 1989. We analyzed variation in egg size of black brant in relation to clutch size, laying date, female age, year, and position in the laying sequence. Egg size increased with clutch size and female age, and decreased with laying date, year, and position in the laying sequence. We did not detect a negative phenotypic correlation between clutch size and egg size. However, overlap in total clutch volumes for clutches of different sizes indicated trade offs occurred among individuals with comparable investments in their clutches. We web-tagged black brant goslings at hatch, recorded their egg size, position in the egg-laying sequence, initial brood size, hatch date, and nesting density and examined the effect of these characteristics on their probability of recapture. Larger broods from larger eggs, and with earlier hatch dates were more likely to be recaptured. There was a tendency for young females to be less successful in rearing their broods; however, this may be related to their egg size, initial brood size, and hatch date, rather than age per se.
    • Presence points and behavioral data of Sarus Crane in Lumbini-Nepal September and October 2014

      Huettmann, Falk; Karmacharya, Dikpal Krishna; Duwal, Rabita (EWHALE Lab, University of Alaska Fairbanks, 2015-06-27)
      This dataset presents geo-referenced summaries of Sarus Crane (Grus antigone) and their behavioral sightings from field work. The Lumbini region is the hot spot with more than 250 species of birds and included as an Important Bird Area (IBA) of Nepal. It comprises beautiful cultural and religious resources. Hence, it is under the World Heritage Site of UNESCO. The occurrence of Sarus Crane in this region has religious value related with Buddhism. The 'presence only' data of Sarus Crane are provided for low land Nepal covering most of the VDCs of Rupandehi and Kapilbastu districts. The bounding box (decimal degrees) of the data coverage is 27.30015 til 27.576548 latitude (North) and 83.36193 til 82.990292 longitude (East), and an altitude covering 72m til 111m above sea level. Eight human resources including two experts and six local observers compiled the field-based data. The data consist of an MS Excel which includes 19 rows and 74 columns with the the following column headings: Time, Day, Month and Year of sightings, Observers, Latitude, Longitude and Elevation (m) of the sighting points, Geo-referencing method, Geographic datum, Location, District, Country, Male, Female, ClusterTotal, Habitat, Behaviour and Remarks. While this data set is relatively small, it reflects a large and complex set of representative information for the entire lowland of Nepal. Altogether 201 Sarus Cranes individuals weer counted including 104 male and 97 female within three habitats and four behaviours of birds are also described in the data. Naturalists, bird watchers, modelers as well as investigators of cranes and other birds in the region of Nepal and Northern India will find good value in this data set.
    • 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.
    • Production of vascular aquatic plants in wetlands of Alaska: A comparative study

      Larsen, Amy Sophia (1997)
      I examined the effects of climate and hydrology on aboveground biomass of macrophytes in wetlands across Alaska by investigating the effects of latitude, July mean air temperature, lake type (open, periodically inundated, and closed), hydrology, and water and sediment chemistry on emergent and submersed vascular plant biomass to determine environmental variables that influenced wetland plant growth. I sampled aboveground biomass of macrophytes in four wetland complexes within Alaska: Kenai and Tetlin National Wildlife Refuges, Minto Flats State Game Refuge, and the Arctic Coastal Plain near Prudhoe Bay, Alaska. In addition to peak aboveground biomass, I also collected water and sediment samples from each lake that were analyzed for water temperature, color, alkalinity, turbidity, pH, orthophosphate, $\rm NO\sb3/NO\sb2$-N, NH$\sb4\sp+$, and total sediment C, N, and P. I found a quadratic relationship between emergent plant biomass and latitude. Minto, the second most northern site, had the greatest plant biomass, Prudhoe Bay, the most northern site had the least, and Kenai and Tetlin had moderate levels of biomass. I found a positive linear relationship between emergent plant biomass and July mean temperature, suggesting that on-site summer condition is important in predicting biomass. Submersed plant biomass was better related to alkalinity, turbidity and sediment P than to latitude, which suggests that climate is not as important in predicting submersed plant biomass as it is in predicting emergent plant biomass. Emergent plant biomass differed spatially and temporally, while submersed plant biomass showed no distinct patterns in variation across the landscape and with changes in hydrologic input. Many water and sediment chemistry variables differed among lake types and between flood regimes. Emergent plant biomass was associated with changes in water level as well as changes in water. Plant species composition differed among lake types and tended to change with flood regime as well. A separate suite of species occupied closed lakes, while open and periodically inundated lakes tended to contain more similar plant species. Both climate and hydrology appear to have a significant impact on emergent and submersed plant biomass and species composition in wetlands of Alaska. These spatial and temporal differences have direct influences on secondary producers living in wetlands of Alaska.
    • Proinflammatory cytokines induce a Rac1-mediated superoxide-dependent reorganization of the actin cytoskeleton in neuronal cells

      Smeets, Shelli Stewart (2002-12)
      A dynamic actin cytoskeleton in central nervous system (CNS) neurons is pivotal for regeneration. Following acute CNS trauma, the proinflammatory cytokines TNF[alpha] and IL-1[beta] become expressed in cells and induce Rac 1-mediated actin filament reorganization. Also, Rac 1 regulates a NAD(P)H oxidase activity that generates superoxide (·O₂). This study's objective was to determine whether TNF[alpha] and/or IL-1[beta] induce a Rac 1-dependent actin filament reorganization in SH-SY5Y neuroblastoma cells and in chick spinal cord neurons via the signaling intermediate, superoxide. SH-SY5Y cells respond to soluble TNF[alpha] or IL-1[beta] with transient, biphasic actin filament reorganization. Over a time period of 30 min, increased membrane ruffling precedes formation of stress fibers and arrest of cell motility, compared to controls. Similarly, in chick growth cones soluble TNF[alpha] or IL-1[beta] for 15 and 30 minute time periods caused increased lamellipodia formation. The actin filament reorganization in both SH-SY5Y cells and chick spinal cord neurons was inhibited by DPI, an irreversible inhibitor of NAD(P)H oxidase, and MnTBAP, a superoxide dismutase mimetic. Conclusively, TNF[alpha] and IL-1[beta] a transient Rac 1-mediated actin filament reorganization, which could block regeneration of injured axons. Our findings that DPI and MnTBAP prevent this reorganization reveals a potential therapy to mitigate the inflammatory response.
    • Properties of sodium sodium chloride brine on laboratory ice

      Gleason, Erin P.; Simpson, William; Trainor, Thomas; Larsen, Jessica (2014-12)
      Snow and ice surfaces are ubiquitous in the environment. Heterogeneous reactions on those surfaces are responsible for a wide range of phenomena such as the Antarctic stratospheric ozone hole, depletion of boundary-layer ozone, and deposition of mercury. Little is known about the location of impurities on ice surfaces or how that structure depends upon temperature and time after contamination. Therefore, we investigated microscopic structures created by depositing sodium chloride particles onto laboratory-grown ice below the hydrohalite-water eutectic temperature. As the temperature was increased above the eutectic, sodium chloride solution (brine) formed around the particle and spread across the air-ice interface. Literature indicated that ice crystal grain boundaries are the most thermodynamically stable site for brine; yet, on our time scale (minutes), the brine does not drain down the grain boundary and is instead present on the ice surface. Either the surface energetics of the system differ from expectations or a barrier inhibits the brine from moving down the grain boundary on the observational timescale. The area of the brine was used to relate surface coverage by our contamination mechanism to bulk composition. We find that brine does not fully coat the surface for typical snow properties.
    • Protein Status Of Muskoxen And Caribou In Late Winter

      Gustine, David D.; Barboza, Perry S. (2010)
      The conservation and management of northern ungulates depends upon our understanding of the influence of habitat associations on the nutritional condition of individuals and population productivity. Adverse foraging conditions in late winter may reduce the availability of body proteins for reproduction. Therefore, assessing nitrogen (N) or protein status in late winter could be a valuable tool to monitor populations of northern ungulates. I collected >1,800 excreta samples to evaluate isotopic metrics of protein status [proportion of serum amino acid N derived from body N (p-AN), proportion of urea N derived from body N (p-UN), and the difference between the isotopic ratios of N (delta15N) in body tissues and urinary urea (DeltaBody-urea)] in captive and wild populations of muskoxen (Ovibos moschatus) and caribou (Rangifer tarandus) in late winter. I evaluated the dynamics of body protein and delta15N in a captive population of female muskoxen (2007). Diets and protein status were assessed in populations of wild muskoxen in northern Alaska (2005--2008); a semi-captive (penned) population of wild, pregnant caribou (2006); and wild populations of migratory and sedentary ecotypes of caribou (2006--2008). Captive female muskoxen lost body protein (~6%) in late gestation and these losses corresponded with the protein deposited in reproductive tissues. The concentration of plasma urea, the p-AN, and p-UN tended to increase throughout winter. During late gestation, most penned pregnant caribou on an ad libitum feeding schedule lost core body mass (55%) and were in negative protein status (54%). For groups of wild muskoxen (n = 30), abundance of preferred forages improved protein status (p-UN; R2 = 0.45). At the foraging sites of wild caribou (n = 32), the amount of shrubs in a lichen-rich diet had a positive effect on protein status (DeltaBody-urea, r2 = 0.26). Foraging constraints in late winter will decrease the amount of body proteins available for reproduction. However, considerable challenges remain to applying the p-UN as a monitoring tool at broad scales for caribou, but with appropriate consideration, isotopic proxies may be used to evaluate environmental constraints for northern ungulates at small scales.
    • Proton transport and auroral optical emissions

      Shen, Deli; Rees, M. H.; Deehr, C. S.; Lummerzheim, D.; Smith, R.; Stamnes, K.; Stenbaek-Neilsen, H. (1993)
      The hydrogen lines are the characteristic emissions of proton aurora and have been used to study the impact of protons upon the atmosphere. Observations of hydrogen emission on the long wavelength side of the unshifted lines were not explained by previous theories. To explain the observed optical emissions, a numerical code is developed to solve the one dimensional, steady state, linearly coupled transport equations of H$\sp+$/H in a dipole magnetic field. For the first time, the mirror force is included in the transport equations to produce backscattered particles which are responsible for emission at wavelengths longward of the unshifted lines. Both downward and upward particle intensities of H$\sp+$/H are calculated. The mirror reflectivities of energy and particles are defined, and their dependences on proton input spectra and pitch angle distributions are studied. The results show that the mirror reflectivity increases both with characteristic energy and with pitch angle of the input proton flux, but is more sensitive to angular distributions than to energy spectra. Energy deposition rate, ionization rate, H$\sb\alpha$, H$\sb\beta$ and Nitrogen First Negative bands emission rates and profiles are calculated. Calculated fluxes of H$\sp+$/H and emission properties of Hydrogen Balmer lines are compared with a rocket measurement. The efficiency for production of the Balmer lines and the Nitrogen First Negative bands is obtained in terms of the energy input rate and the H$\sp+$ particle flux. A Doppler shift of about 3.0 A toward the blue for magnetic-zenith profiles of H$\sb\alpha$ is obtained, compared with observational results of $6.0 \pm 2.0$ A. The calculated emissions on the red side of the unshifted hydrogen atomic emission lines when convolved with the instrumental function accounts for the observed emissions on the long wavelength side of the unshifted hydrogen Balmer lines.
    • Provenance and diagenesis of the Miocene Bear Lake Formation, Bristol Bay basin, Alaska

      Hartbauer, Cheryl Lynne (2010-08)
      The Miocene Bear Lake Formation (BLF) is a prospective hydrocarbon reservoir exposed on the southwestern Alaska Peninsula, extending into the subsurface to the northwest (reaching 2,360 m maximum thickness). This study comprehensively characterizes composition of BLF sandstones, and develops important implications for varying reservoir quality. Unique integration of standard petrographic methods, electron microprobe analysis (EMPA), and ⁴⁰Ar/³⁹Ar dating of detrital hornblende strengthens interpretations by providing multiple lines of evidence and a more complete picture of composition, source units and terrane, and diagenetic history than possible with petrography alone. EMPA provides superior classification of volcanic rock fragments and identification of diagenetic minerals. Results indicate a pressure-controlled diagenetic system, and a provenance more complicated than recycling of older strata, as currently interpreted. Simultaneous derivation from the Meshik Volcanics and recycling of Tolstoi, Chignik, and Naknek formations suggests erosion of a structurally-deformed source terrain (e.g. reverse-faulted anticlines). Abundance patterns of pore-filling zeolites, calcite, albite, and kaolinite likely represent variations in Pco₂ caused by variations in burial depth. Optimal reservoir quality is likely present in the subsurface upper BLF along the northwestern coast (and deeper in the basin), where sandstone composition is presumably more quartz-rich, less volcaniclastic, and has experienced higher Pco₂ fluid migration.
    • Putative pheromones in the urine of male moose: evolution of honest advertisement?

      Whittle, Chris Linda (1999-12)
      I tested hypotheses about how olfactory communication is related to mating behavior in Alaskan moose (Alces alces gigas). Males dig rutting pits where urine is deposited to which females strongly respond. Consequently, male urine may contain primer pheromones that synchronize estrus of females. Urine samples were collected from captive moose on the Kenai Peninsula, Alaska. Samples included those from the mating season and from the nonrutting period for two adult males, one yearling male, and one male and one female calf. After pH adjustment, samples were extracted with methylene chloride to yield 3 fractions (acidic, neutral, and basic), which were analyzed by gas chromatography-mass spectrometry. Putative pheromones include unsaturated alcohols and homologs of tetrahydro-6-methyl pyranone, and 2-nonen-4-one. I hypothesize that these compounds are related to hypophagia and catabolism of body reserves by rutting males, and thereby provide an honest advertisement of body condition in moose.