• Coupling the effects of dissolved organic matter and nutrient Stoichiometry with nutrient uptake in boreal forest headwater streams

      Fjare, Dana; Jones, Jeremy; Harms, Tamara; Kielland, Knut (2015-08)
      Discontinuous permafrost affects the hydrology and distribution of vegetation in boreal forest watersheds, which in turn influence stream water chemistry. I investigated how loss of discontinuous permafrost with projected climate change might affect nutrient cycling in boreal forest headwater streams. I hypothesized that 1) the carbon, nitrogen, and phosphorus (C:N:P) ratio in dissolved organic matter (DOM) affects nutrient uptake due to stoichiometric constraints on autotrophic and heterotrophic nutrient assimilation, and 2) labile DOM affects nutrient uptake by increasing heterotrophic production. I tested my hypotheses using a series of instantaneous nutrient additions in nine headwater streams, with a factorial design manipulating both nutrient stoichiometry and DOM source. DOM was added as either acetate or leachate from birch leaves. Ambient nutrient uptake velocity (Vf-amb) was within the upper range of previously published literature values, ranging from 4.1-67.2 mm/min for N, 4.0-25.0 mm/min for P, and 4.2-34.5 mm/min for acetate. Uptake efficiency was similar for N and P added alone, in co-additions, and with DOM. Acetate and birch-DOM had similar effects on nutrient uptake, because both were sources of highly labile carbon. In 30-day laboratory bioavailability assays, birch and acetate-DOM exhibited ≥ 70% carbon loss. Vf-amb was in part explained by ambient stream chemistry, with Vf-amb for N weakly positively correlated with ambient P concentration, while Vf-amb for P and acetate was weakly negatively correlated with ambient N and ambient dissolved organic carbon, respectively. Consequently, inorganic nutrient availability may affect uptake of solutes as well as DOM lability. High demand for nutrients in boreal forest headwater streams suggests that uptake could increase concurrently with greater inorganic nutrient flux following a loss in permafrost extent.
    • Cowboy professionalism: a cultural study of big-mountain tourism in the last frontier

      Wagner, Forest J.; Cole, Terrence; Ehrlander, Mary; Heyne, Eric (2017-08)
      Geographical features and cultural traits may influence the character of big-mountain tourism in Alaska. For example, Alaska's wild landscape, rich climbing and skiing history, and cultural mythos of wilderness and frontier fostered its status as a major destination for niche big-mountain tourism. Growth in the industry since the 1980s has been phenomenal, though a change threatens the identity of mountain guides of the region, demanding they accept international standards for their self-regulating and uniquely Alaskan version of big-mountain tourism. This research project explored big-mountain niche tourism in Alaska, considering the influences of wilderness and frontier concepts on the tourism culture and examining guides' and clients' motivations for participation in the industry. I queried clients and guides at two guiding services, the Alaska Mountaineering School and its Denali mountain climbers, and Alaska Powder Descents and its Coast mountain heli-skiers. The quantitative client survey assessed participant motivations for engaging in big-mountain tourism, for hiring a guide, and for travelling to engage in mountain tourism. The qualitative guide interview asked guides their motivations for working in big-mountain tourism, their experience with the management of big-mountain risk, and changes they had observed over time in the industry. I am a professional mountain guide and instructor in Alaska and use this experience as a third data point. The findings showed that Alaska's big-mountain tourism offers individuals a transcendental, sublime, yet physical encounter, one that is part of a globalized political and economic system. Except for the guides themselves, the high mountains are generally accessible only to those who are at the high end of the socioeconomic spectrum. Gender is also a defining characteristic of the industry, as the guiding ranks and the clientele in Alaska's big-mountain tourism are overwhelmingly male. For guides, the frontier mythos of intrepid and rugged individualism is a powerful motivator, an identity construction that relates well with the depictions of the region in early literature, and in images promoted by the tourism industry. Clients on the other hand may come to Alaska because it is geographically exceptional, but they are not as enamored of the frontier ideology that resonates so deeply with many permanent residents.
    • Creating, communicating and measuring strategic objectives through the application of a balanced scorecard: the case of the University of Alaska Fairbanks Police Department

      McGee, Sean Eric; Duke, Rob; Berry, Kevin; May, Jeffrey (2015-08)
      This project served to align the vision and mission of the University of Alaska Fairbanks Police Department with the needs of the University community through the employment of a balanced scorecard. The balanced scorecard itself is a strategic performance management framework that enables organizations to identify, manage and measure strategic objectives. While there have been instances where police agencies have attempted to implement the balanced scorecard in the past, these police agencies have been very large, and they failed to achieve the level of granularity in their balanced scorecard necessary to effectively identify and manage true strategic objectives. In case of the University of Alaska Fairbanks Police Department, the balanced scorecard served to answer four fundamental questions: how will they sustain their ability to change and improve, what business processes must they excel at, how should they be perceived by their community, and how can they be responsible stewards of the funds that they are given?
    • Critical Parameters In Magmatic Degassing

      Mongrain, Joanna; Larsen, Jessica (2008)
      Decompression experiments conducted at pressures up to 200MPa and temperatures of 825�C-880�C on hydrated K-phonolite and rhyolite melts were used to explore the critical parameters controlling nucleation, exsolution and degassing behavior. Experiments on the low viscosity/surface tension K-Phonolite melt highlighted the role of melt properties. Although the sample porosities deviated below equilibrium values for pressures less than ~40MPa, the melt exsolved water in equilibrium over all the pressures and decompression rates studied. Melt shearing is proposed to have caused bubble deformation and alignment, lowering the porosity at which extensive permeability develops and significant degassing occurs compared to rhyolite. Experiments on a rhyolite melt decompressed slowly from 100 MPa and then held at 10 MPa for up to 900 s highlighted the critical parameters controlling the formation and stability of a highly vesicular magma: bubble number density, bubble size distribution and porosity. The porosity of the interconnected, highly vesicular network decreased during "Stage I" degassing and the bubble size distribution evolved from a unimodal population to include a population of much larger bubbles. During Stage II degassing, the network collapsed. Pre-collapse and collapse degassing rates were obtained and a coalescence-induced coalescence model proposed to explain the rapid destabilization. The ability of a melt to efficiently exsolve volatiles and the ease of bubble coalescence are both a function of the initial distribution of nucleated bubbles. The development of a new method for quantifying this distribution using spatial statistics will allow future researchers to explore the underlying controls on nucleation such as melt structure and the occurrence of a prior nucleation event. To investigate the critical parameters controlling shallow dike intrusion and therefore magmatic ascent rate, the fracture mechanics of intrusion into homogeneous and layered (weak sandstone/strong granite) particle models under lithostatic, compressive and extensional regimes were examined. Although the scale of the model intrusions were an order of magnitude greater than field observations, extensive microfracturing across the weaker layers, parallel dike jointing in the stronger layers and a length scale dependence to fracture toughness were observed suggesting that the use of a particle code is a promising approach to intrusion modeling.
    • Critical points of the heat kernel on a compact semisimple Lie group

      Korotiaev, Mikhail B. (2002-08)
      Critical points of the heat kernel on a compact semisimple Lie group are studied. The necessary background topics from abstract harmonic analysis, Lie group and Lie algebra theory, and Riemannian geometry are discussed. The fact that the heat kernel is a smooth class function on a compact semisimple Lie group is used to obtain partial results concerning location and degeneracy of its critical points. Original results on critical points of smooth class functions on a compact semisimple Lie group are presented in the last chapter.
    • A critique of some dynamic analyses of Silver Bay, Alaska

      Calegari, James P. (1968-05)
      The equations of motion and energy for an estuarine system are set up. The mean equations are obtained and the averaging operator is investigated. A comparison between the Silver Bay theory is made. The importance of the averaging process, the mean steady state, the tidal velocity and the lateral velocity are re-evaluated. The simplified mean equations of flow are then obtained. The numerical equation for evaluation of pressure gradients and the velocity cross-products are obtained. Curvature effects are found to be of importance. Second order terms are investigated and numerical equations for the evaluation of vz are found. Some data from the Alaska Water Pollution Control Board is investigated. It is found that the Silver Bay Study neglected to consider some important factors. Lateral flows tidal motion and river run-off need more consideration. A Statistical consideration of data is found to be important. By hypothesis testing a clearer concept of the values of the assumptions can be made. It is found that much more data is needed.
    • Crop modeling to assess the impact of climate change on spring wheat growth in sub-Arctic Alaska

      Harvey, Stephen K.; Zhang, Mingchu; Karlsson, Meriam; Fochesatto, Gilberto (2019-05)
      In the sub-arctic region of Interior Alaska, warmer temperatures and a longer growing season caused by climate change could make spring wheat (Triticum aestivum L.) a more viable crop. In this study, a crop model was utilized to simulate the growth of spring wheat in future climate change scenarios RCP4.5 (medium-low emission) and RCP8.5 (high emission) of Fairbanks, Alaska. In order to fulfill such simulation, in 2018 high quality crop growth datasets were collected at the Fairbanks and Matanuska Valley Experiment Farms and along with historic variety trial data, the crop model was calibrated and validated for simulating days to maturity (emergence to physiological maturity) and yield of spring wheat in Fairbanks. In the Fairbanks 1989-2018 (baseline) climate, growing season (planting to physiological maturity) average temperature and total precipitation are 15.6° C and 122 mm, respectively. In RCP4.5 2020-2049 (2035s), 2050-2079 (2065s), and 2080-2099 (2090s) projected growing season average temperature and total precipitation are 16.7° C, 17.4° C, 17.8° C and 120 mm, 112 mm, 112 mm, respectively. In RCP8.5 2035s, 2065s, and 2090s projected growing season average temperature and total precipitation are 16.8° C, 18.5° C, 19.5° C and 120 mm, 113 mm, 117 mm, respectively. Using Ingal, an Alaskan spring wheat, the model simulated days to maturity and yield in baseline and projected climate scenarios of Fairbanks, Alaska. Baseline days to maturity were 69 and yield was 1991 kg ha-1. In RCP4.5 2035s, 2065s, and 2090s days to maturity decreased to 64, 62, 60 days, respectively, and yield decreased 2%, 6%, 8%, respectively. In RCP8.5 2035s, 2065s, and 2090s days to maturity decreased to 64, 58, 55 days, respectively, and yield decreased 1%, 3%, then increased 1%, respectively. Adaptation by cultivar modification to have a growing degree day requirement of 68 days to maturity in RCP4.5 2035s and RCP8.5 2035s resulted in increased yields of 4% and 5%, respectively. Climatic parameters of temperature and precipitation per growing season day are projected to become more favorable to the growth of spring wheat. However, precipitation deficit, an indicator of water stress was found to stay similar to the baseline climate. Without adaption, days to maturity and yield are projected to decrease. Selection and/or breeding of spring wheat varieties to maintain baseline days to maturity are a priority to materialize yield increases in the area of Fairbanks, Alaska.
    • Cross-seasonal effects on reproductive performance of Pacific black brant

      Schamber, Jason Lee (2001-12)
      We used re-sightings of Pacific Black Brant from San Quintin Bay, Ojo de Lieber Lagoon, and San Ignacio Lagoon, Baja California and Boundary Bay, British Columbia, to examine winter population structure, variation in structural size and the importance of winter location to individual reproductive performance at the Tutakoke River colony. Sexes of adults and juveniles were distributed equally among winter locations. Adult structural size and mean age were similar among winter locations. A higher proportion of juveniles over-wintered in San Quinton Bay and Ojo de Liebre Lagoon. Individuals wintering at Ojo de Liebre and San Ignacio lagoons were less likely to breed and initiated clutches later than those that wintered in Boundary Bay or San Quinton Bay. Maternal mass did not vary, although clutch size was slightly larger in individuals that wintered in southern areas. Variation in winter location and habitat quality could influence individual reproductive performance and population dynamics.
    • Crude oil bioremediation in Arctic seashore sediments

      Sharma, Priyamvada; Schiewer, Silke; Trainor, Thomas; Schnabel, William (2015-08)
      Oil is an important energy source but also an environment pollutant. Crude oil spills along Arctic shorelines might occur due to the expected increase in offshore oil production. To reduce adverse effects on the environment in the case of a spill, it is important to develop approaches to remove spilled oil. Bioremediation with addition of nutrients has shown promising results in enhancing oil degradation rates. This research focuses on determining the effect of different environmental conditions on the rate of crude oil biodegradation in laboratory experiments, as a proxy for oil spills at Arctic seashores. Laboratory microcosms were set up containing beach sediments collected from Barrow, spiked with North Slope Crude. These microcosms were incubated at varying temperatures (3°C vs. 20°C), salinities (30 vs. 35 g/L) and crude oil concentrations (1 vs. 5 mL/kg), all with a standard concentration of nutrients. Measurements of respiration rates (breakdown of hydrocarbons to CO₂), hydrocarbons remaining in the sediment (GC/FID), and hydrocarbons volatilized and sorbed to activated carbon (GC/MS) were performed. In all microcosms, higher respiration rates by naturally occurring microorganisms were observed at 20ºC compared to 3°C. Surprisingly, volatile organic compounds (VOC) release was similar at both temperatures, for different crude oil concentration and salinities. High total petroleum hydrocarbon (TPH) levels remained at 3°C for microcosms with high initial crude oil concentration. Regardless of temperature, increased salinity had a positive impact on the rate of crude oil removal, i.e. high CO₂ release, high VOC production and low amount of TPH in sediments. At higher crude oil dosages, a larger amount of volatiles was released, however CO₂ production did not significantly increase with the contaminant concentration. The results of this study will assist decision-makers in choosing effective spill response strategies for future crude oil spills in Arctic shorelines.
    • Crustal and upper mantle velocity structure in Alaska

      Searcy, Cheryl Kaye; Christensen, Douglas; Layer, Paul; Stringer, William; Kawasaki, Koji; Stone, David (1996)
      The crustal and upper-mantle velocity structure of Alaska testifies to a complex tectonic framework. Much of the structure and history of this framework remains to be conclusively determined. This thesis presents the results of three independent investigations of velocity structure in Alaska in an attempt to provide some insight into its tectonic development. The first study involved the analysis of receiver functions to determine velocity structure beneath College Station (COL), located in Fairbanks, Alaska. Receiver functions from several back azimuths facilitate a fairly detailed analysis of deep crustal velocity structure beneath COL, including an indication that Moho dips to the northeast. The second study also employed receiver function methods to investigate velocity structure for four temporary three-component seismic stations placed in the Brooks Range. Due to the short deployment of these stations in the Brooks Range only a rough estimate of crustal velocities were obtained. Nevertheless, crustal thickening beneath the Brooks range is clearly indicated by an increase in the depth to Moho. The final study undertaken was a three-dimensional tomographic P-wave velocity inversion for the subduction zone region of south central Alaska. Data for the tomographic inversion consisted of local and teleseismic ray paths. The resulting velocity perturbations indicate a positive velocity anomaly associated with the subducting Pacific plate. Furthermore, the tomographic images clarify physical characteristics of the subducting plate such as structure, thickness, and depth of penetration into the mantle.
    • Crustal Deformation Along The San Andreas Fault And Within The Tibetan Plateau Measured Using Gps

      Chen, Qizhi; Freymueller, Jeffrey T. (2002)
      Using the Global Positioning System (GPS), we study crustal deformation along the San Andreas Fault (SAF) in the San Francisco Bay area and within the Tibetan Plateau, and provide new constraints for the kinematics of these actively deforming plate boundaries. GPS measurements in 1996 and 1997 and Electronic Distance Measuring (EDM) data from the 1970s and 1980s at sites along the SAF in northern California were used to determine the near-fault strain rate and to investigate the slip rate, locking depth, and rheology. We found a pronounced high near-fault shear strain rate that can be explained by a 2-D inhomogeneous model in which a low-rigidity compliant zone concentrates strain near the fault. We suggest that the materials on either side of the fault and the cumulative fault offset play a role in the development of the compliant zone. If such a compliant zone is present but unmodeled, the geodetic estimates of slip rate and locking depth (seismogenic depth) would be biased. This would lead to a miscalculated seismic hazard. Thirteen GPS sites in southern Tibet, surveyed in 1995, 1998 and 2000, were merged with other data from China and Nepal into a single, self-consistent velocity field. The Himalaya and southern Tibet was modeled using a kinematically-consistent block model and elastic dislocation theory. We show a significantly lower convergence rate between India and Eurasia in central Himalaya than that previously estimated. We observe that southern Tibet undergoes non-uniform (spatial) east-west extension with one-half of the extension across the Yadong-Gulu rift. We infer that spatially non-uniform extension in southern Tibet results in variation of the arc-normal convergence rates along the Himalaya, and that the Yarlung-Zangbo suture or adjacent structure may be active as a right-lateral strike slip fault. From 44 GPS sites in the Tibetan Plateau, we show that deformation of Tibet is distributed and strain accumulation is spatially uniform across the entire plateau. We propose a kinematic model for the Tibetan Plateau to be a combination of rigid block motion, pure shear and uniaxial contraction in the direction of about N32�E, comparable to the convergence direction between India and Eurasia.
    • Crustal Deformation In Alaska Measured Using The Global Positioning System

      Fletcher, Hilary Jane; Freymueller, Jeffrey T. (2002)
      Repeat observations using the Global Positioning System at sites on the Earth's surface enable the velocity of those sites to be estimated. These velocity estimates can be used to model the processes of the crust's deformation by faulting and folding. The focus of this study is crustal deformation in Alaska and in particular the region of interior Alaska within 300km of Fairbanks, including the Denali fault; the Fairweather fault and Yakutat block in southern Alaska; and the Semidi region of the Aleutian arc. This deformation is driven by the relentless northwestward motion of the Pacific plate relative to North America. The Yakutat block, an allocthonous terrane located in the 'armpit' of southern Alaska is shown to be moving at neither the Pacific Plate rate nor is it attached to North America. Instead it has a velocity parallel to the Fairweather fault, which means that some offshore structure, possibly the Transition Zone, must accommodate some of the Pacific-North American relative motion. The slip on the Fairweather fault is estimated to be 44 +/- 3 mm/yr with a locking depth of 8 +/- 1 km, which implies a recurrence time of ~80 years for an MS 7.9 earthquake. Using a model of southern Alaska block rotation with the Denali fault as the northern boundary, the slip rate on the McKinley segment of the Denali fault is estimated to be ~6--9 mm/yr for a locking depth of 12 km. Moving to the southwest, data from sites in the Semidi segment of the Alaska subduction zone, between the fully-coupled segment to the northeast and the slipping Shumagin segment to the southwest are studied. This region, which sustained a magnitude 8.2 earthquake in 1938, is determined to be highly coupled and accumulating strain. Finally, all of these pieces are connected in a quantitative model for southern Alaska. This model involves three crustal blocks, the Yakutat block, Fairweather block and southern Alaska block, which lie between North America and the Pacific plate and move relative to these major plates.
    • Crustal Thickness Variation In South Central Alaska: Results From Broadband Experiment Across The Alaska Range

      Veenstra, Elizabeth (2009)
      The Broadband Experiment Across the Alaska Range (BEAAR) was a passive source seismic study in which 36 three-component broadband seismic stations were deployed over a period of 27 months to collect high quality data to study the Alaska Range and perhaps elucidate tectonic processes. The wavetrain of a teleseismic body wave may be interpreted in terms of reflection and transmission of waves converted at discontinuities. The recorded signal may be regarded as a convolution of the source-time function, the receiver function, and the instrument response. A receiver function is the contribution to the seismic waveform recorded at a single station due to the response of local crustal structure, and can be inverted for vertical velocity structure beneath the three-component broadband seismic station. Receiver function analyses reveal typical crust beneath the lowlands north of the Alaska Range is 26 km thick, while beneath the mountains typical crust is 35--45 km thick. Receiver function analysis of ~15,000 teleseismic waveforms recorded by BEAAR broadband seismometers provided over 100 crustal thickness data points. Similarity between crustal thicknesses determined from receiver function analysis and crustal thicknesses predicted from topography assuming Airy isostasy indicate the observed crustal root is sufficient to support the Alaska Range. North of the range, however, the crust is systematically thinner than predicted by simple Airy isostasy. A crustal density contrast of 4.6% across the Hines Creek Fault 2700 kgm-3 to the north and 2830 kgm-3 to the south, explains the observed difference between the crustal thicknesses predicted by simple Airy isostasy and the crustal thicknesses determined by receiver function analysis. Our results indicate that variations in both crustal thickness and density are required to explain the seismic and gravity data. Crustal thicknesses across the central Alaska Range suggest that these mountains are supported by a crustal root developed due to contractional thickening. Crustal thickness data reveal differences in terrane thickness: a thin Yukon-Tanana terrane north of the Hines Creek fault and thicker Kahiltna/Wrangellia terranes to the south. Finally, the pattern of thin crust to the north and thicker crust to the south appears to be modified by late Cenozoic structures such as the Denali fault, with contractional thickening in the Alaska Range, including areas north of the Hines Creek fault in the northern foothills fold and thrust belt. BEAAR crustal thickness data suggest that major faults extend to the base of the crust.
    • Cubesat Attitude Control Utilizing Low-Power Magnetic Torquers & A Magnetometer

      Mentch, Donald B.; Thorsen, Denise (2011)
      The CubeSat Project has lowered development time and costs associated with university satellite missions that conform to their 10 centimeter cube design specification. Providing attitude control to a spacecraft, of such small volume, with a very limited power budget has been a challenge around the world. This work describes the development of an attitude control system based on a very low-power magnetic torquer used in conjunction with a magnetometer. This will be the first flight use of this torquer which is composed of a hard magnetic material wrapped inside of a solenoid. By discharging a capacitor through the solenoid, the magnetic dipole moment of this permanent magnet can be reversed. The completed attitude control system will make the first use of the low-power magnetic torquer to arrest satellite tip-off rates. It will then make the first known use of a dual axis magnetic dipole moment bias algorithm to achieve three-axis attitude alignment. The complete system is standalone for high inclination orbits, and will align the spacecraft to within 5 degrees of ram, nadir, and local vertical, without any requirement for attitude determination. The system arrests tip-off rates of up to 5� per second (in all 3 axes) for a satellite in a 600 kilometer polar orbit expending 0.56 milliwatts of power. Once in the proper alignment, it utilizes 0.028 milliwatts to maintain it. The system will function for low inclination orbits with the addition of a gravity boom. The system utilizes the magnetometer to calculate spacecraft body rates. This is the only known use of a magnetometer to directly measure spacecraft body rates without prior knowledge of spacecraft attitude.
    • Cultivating Sustainability Through Participatory Action Research: Place -Based Education And Community Food Systems In Interior Alaska

      Henry-Stone, Laura R.; Barnhardt, Ray; Gerlach, Craig; Kofinas, Gary; Webster, Joan Parker (2008)
      As the environmental movement grows into a broader sustainability revolution, we must move beyond the traditional scope of environmental education to address social-ecological challenges through integrated education for sustainability. This research explores how place-based education can promote sustainability of a community food system in which feedbacks between production and consumption are integrated within a biocultural region. Through participatory action research, the project develops and demonstrates pedagogical components of sustainability that are applicable to formal and non-formal educational contexts. In this pedagogy, the purpose of sustainability education is to foster a community culture that will promote the emergence of sustainability in complex adaptive systems with social and ecological components. This work is based at the Effie Kokrine Charter School (EKCS), a junior-senior high school in Fairbanks, Alaska that teaches with an Alaska Native approach, emphasizing place-based, experiential, and holistic education by utilizing students' natural and human communities to facilitate learning. The collaborative design of an Interior Alaska gardening curriculum serves as both an organizing framework for the project's fieldwork as well as an outcome of the research. The resultant gardening curriculum and the rationale behind its design demonstrate components of pedagogy for sustainability, including systems thinking, place-based and problem-based learning, eco-cultural literacy, eco-justice values, and appropriate assessment. Sustainability pedagogy within settings of higher education should also include action research. The structure of this dissertation research reflects how action research incorporates components of sustainability pedagogy. This pedagogical framework has theoretical and practical implications in multiple educational settings and indicates ways for our educational institutions to participate in the global sustainability revolution.
    • Culturability, Temporal Change, Phylogenetic Analysis, And Yield Of Bacterial Communities In A Subarctic Lake: Harding Lake

      Zhao, Xiaoming; Button, Don (2005)
      Heterotrophic bacteria, adapted to small concentrations of substrate, are a main component of the microbial flywheel. However, understandings of their activity, isolation, genetics, and nutrition are restricted to the large, easily isolated and culturable bacteria. By using the dilution culture method, apparent culturabilities could approach 10% in unamended lake water and were inversely proportional to the number of cells inoculated from mixed species in a natural environment from Harding Lake. Substrate additions could not improve bacterial culturability in the dilution cultures. Comparative sequence analyses of 16S rDNA genes showed that all bacterial species have similar lengths in the phylogenetic tree, suggesting similar evolution rates. These indicated close relationships among the six bacterial divisions: alpha-proteobacteria, beta-proteobacteria, gamma-proteobacteria, cytophaga/flexibacter/bacteriodes, acidobacteria, and cyanobacteria. Possible reasons include that metabolic enzymes of these bacteria were modified to adapt to low temperatures from tropical temperatures in arctic areas at the same time. These findings may provide insight into the recent evolution of the bacteria in near polar freshwater. Moreover, a high abundance of alpha-proteobacteria and gamma-proteobacteria was found in Harding Lake, suggesting high growth rates of these bacteria in the freshwater region. This is consistent with a rapid continuous shift in the distribution of dominant species observed in Harding Lake, according to the TRFLP, DGGE, and flow cytometry data. Our results also suggested that input of dissolved organic matter derived from terrestrial plants and soils, introduction of terrestrial bacteria, and bacteria themselves led to the bacterial species shifts associated with the seasonal change. Bacterial growth yield is used to measure this carbon conversion efficiency. However, bacterial growth yields have been seriously underestimated in previous studies. Our in situ values for bacterial growth yield from an amino acid mix were actually closer to 50% and 70% in active systems by using a modified, sensitive and accurate method and increased with the increase of temperature between 1�C and 6�C.
    • Cultural activity and market enterprise: a circumpolar comparison of reindeer herding communities at the end of the 20th century

      Koskey, Michael Stephen (2003-12)
      Reindeer herding throughout the circumpolar North is in decline. Investigating this decline, this dissertation takes a comparative approach with a focus on four case studies: the Chukchi of Chukotskii Peninsula, the Iñupiat of the Seward Peninsula, the Saami of the Kola Peninsula, and the Saami of Finnmark. Because various rates and types of decline are occurring in these different cases, a comparative method leads to a systematic analysis of how patterns develop in the practice of contemporary reindeer herding, both locally and globally. Comparing and contrasting the trajectories of declines in reindeer herding identifies and explains the dimensions of specific local-global processes, and situates them in wider contexts. These dimensions include economic incompatibilities, ecological stresses, and power inequities. By focusing on changes in reindeer herding over the last decade, this study reveals the effects of the incorporation of reindeer herding into the global economy, which is heavily dependent on existing infrastructure. This study also demonstrates the social position of reindeer herders and the cultural meaning of reindeer herding to the herders themselves. The willingness of regional and national governments to subsidize herding, and to ensure its survival through consistent access to pastures, is critically important to the success of reindeer herding as a productive agricultural enterprise. Furthermore, changing ecological factors potentially threaten reindeer herding as a subsistence activity. The consequences of decline, then, are explained through the identification of decline-inducing factors, such as ecological change, political vagaries, and the inappropriateness of reindeer herding as a capital-based enterprise under existing conditions of market and transportation infrastructural development.