• Kelp beds as fish and invertebrate habitat in southeastern Alaska

      Calvert, Elizabeth L.; Stekoll, Michael; Shirley, Thomas; Hillgruber, Nicola (2005-08)
      Throughout the temperate marine regime, the shallow subtidal is dominated by rocky reefs and algal assemblages. The ecological significance of high-latitude, cold-water kelp systems is poorly understood particularly for Alaska. Two large-scale experiments conducted near Juneau, Alaska were designed to study fish and invertebrate assemblages in regard to (1) canopy forming Nereocystis luetkeana (1500 m² manipulations) and (2) sub-canopy forming Laminaria bongardiana (600 m²). Fish and invertebrates were quantified using Standard Monitoring Units for the Recruitment of Fish (SMURFs), light traps, and visual surveys. The canopy kelp experiment revealed significantly greater abundance (X=0.57 fish/SMURF; X=0.28 fish/SMURF) and biomass (X=0.95 g/SMURF; X =0.23 g/SMURF) of benthic fishes at Nereocystis sites versus sites without canopy kelp. In contrast, a direct negative effect of Nereocystis was observed for schooling fish; significantly more fish were observed at sites without canopy kelp as compared to Nereocystis sites (X=27.3 fish/15 m³; X=4.2 fish/15 m³). Fish assemblages were independent of L. bongardiana, yet invertebrates were twice as abundant at sub-canopy sites. Nereocystis has direct and indirect effects on fish distributions through behavioral and habitat modifications. Overall, canopy kelps with associated sub-canopy kelps promote more abundant and rich fish assemblages in southeastern Alaska, while invertebrate assemblages are greater in sub-canopy areas.
    • Kelp forests and barren grounds: phlorotannin production and holdfast community structure in the Aleutian dragon kelp, Eualaria fistulosa

      Schuster, Martin D.; Konar, Brenda; Iken, Katrin; Coyle, Kenneth (2012-12)
      The canopy forming kelp Eualaria fistulosa inhabits two organizational states throughout the Aleutian archipelago, kelp forests and barren grounds. Urchin abundance and behavior determines which state dominates in any given area. Sporophyll phlorotannin content and holdfast epibiont fauna were investigated at multiple islands along the Aleutian archipelago to determine how the organizational state affects the production of secondary metabolites and the taxon richness, abundance and biomass of holdfast communities. Barren ground sporophylls had higher phlorotannin content than kelp forest sporophylls, although grazing rates on sporophylls from each state did not differ during in situ grazing experiments. The taxon richness, abundance and biomass of holdfast communities were similar between kelp forests and barren grounds at all islands, although these communities varied among islands and were mostly driven by holdfast volume. These results suggest that physical differences such as light and nutrient availability in the kelp forest structure between organizational states may be responsible for differences in phlorotannin content, but that these differences are not reflected in the holdfast community structure. It appears that barren ground holdfast communities are remnants of a once forested area.
    • Kelvin-Helmholtz Instability And Magnetic Reconnection At The Earth's Magnetospheric Boundary

      Ma, Xuanye; Otto, Antonius; Lummerzheim, Dirk; Newman, David; Ng, Chung-Sang; Zhang, Hui (2012)
      Magnetic reconnection and Kelvin-Helmholtz (KH) instability are the two most important mechanisms for plasma transport across the Earth's magnetospheric boundary layer. Magnetic reconnection is considered as the dominant process for southward interplanetary magnetic field (IMF), and the KH instability is suggested to play an important role for northward IMF. It is interesting to note that this plasma entry is associated with a dramatic entropy increase, which indicates the existence of strong nonadiabatic heating during the entry process. Observations indicate a plasma entropy increase by two orders of magnitude during the transport from solar wind into the Earth's magnetosphere. Therefore, it is important to examine whether magnetic reconnection can provide sufficient nonadiabatic heating to explain the observed plasma properties and to identify plasma conditions that allow strong nonadiabatic heating. This thesis demonstrates that the entropy can indeed strongly increase during magnetic reconnection provided that the plasma beta, i.e., the ratio of thermal to magnetic energy density is small. A realistic three-dimensional configuration of the Earth's magnetopause for southward IMF conditions includes large anti-parallels magnetic components with a fast perpendicular shear flow. Thus, it is expected that KH modes and magnetic reconnection operate simultaneously and interact with each other. This thesis provides a systematic study on this interaction between reconnection and KH modes by means of three-dimensional MHD and Hall MHD numerical simulations. It is demonstrated that both reconnection and nonlinear KH waves change the other modes onset condition by changing the width of the transition layer. It is shown that dynamics of the system can be strongly modified by a guide field or Hall physics. In the presence of plasma flow, magnetic reconnection is also associated with the generation of field-aligned currents (FACs), which play a critical role in the coupling between the magnetosphere and ionosphere. This thesis also examines systematically the generation of FACs. It is demonstrated that such currents are generated either by a guide magnetic field, by shear flow, or by the inclusion of Hall physics already in two-dimensional magnetic reconnection.
    • Kids Getting Away With Learning: Student Perceptions Of Learning In One To One Laptop Programs

      Standley, Mark; Monahan, John; Crumley, Robert; Jorgensen, Spike; Lang, Rob; Richey, Jean; Roehl, Roy (2012)
      This research explores students' perceptions of learning in one to one laptop programs in rural Alaska. This research used constructing grounded theory methods by conducting five focus groups in rural high schools in order to gather and analyze data from the students themselves. The research intent was to let the students' words and experiences shape a new theory how about they learn with these laptop programs. From an epistemological standpoint the goal of this qualitative research was to create a more complete picture of learning in one to one programs using grounded data through gathering, analyzing, and working directly with the students in these programs as "co-participants" to learn from their perceptions of learning using laptops. The new literacies student develop through being 21st century learners were reflected in the student perceptions in one to one programs and challenge researchers to re-examine learning theory in light of the ubiquitous nature of digital learning. This research was part of a larger collaboration with the Tech Cohort (Appendix A) to conduct mixed methods research using the same population to create a more complete picture of the research topics and participants.
    • The kinetics of glucose limited growth by a marine yeast

      McNab, Allen David (1969-05)
      The kinetics of glucose limited growth by a marine yeast, shown to be a Rhodotorula species, have been studied in a continuous culture apparatus. The saturation constant, in synthetic media, has been calculated to be 0.25 mg/l, on the assumption that saturation kinetics are followed, The maximum growth rate was determined in both synthetic media, and artificial sea water. On the basis of inhibition kinetics, the kinetic behavior of this yeast in the marine environment has been predicted. The effect of temperature on the maximum growth rate has been determined and, on the assumption of a similar effect on the saturation constant, the saturation constant has been postulated to be in agreement with similar values determined for other microorganisms.
    • King eider migration and seasonal interactions at the individual level

      Oppel, Steffen; Powell, Abby; Murphy, Edward; Verbyla, Dave; O'Brien, Diane (2008-12)
      Seasonal interactions describe how events during one season of the annual cycle of a migratory bird affect its fitness in subsequent seasons. Understanding the strength and mechanism of seasonal interactions is important to predict how migratory birds will respond to future challenges caused by habitat loss and climate change. This dissertation explores seasonal interactions between different stages of the annual cycle in an arctic-breeding sea duck, the King Eider (Somateria spectabilis). Concerns over recent population declines and potential effects of climate change on marine habitats used by the species highlight the need for a better understanding of its life history. I used satellite telemetry to describe migration routes, timing of migration events, and geographic regions used by King Eiders throughout the year. I found highly variable movement patterns, and wide dispersion of King Eiders to three regions in the Bering Sea during winter. I then developed stable isotope techniques to examine seasonal interactions at the individual level. First, I examined the relative contribution of body reserves to egg production using stable isotope analysis of egg components and blood. I found that most birds use only small proportions of body reserves to produce eggs, but rather rely on nutrients obtained on breeding grounds to form a clutch. Thus, contrary to general expectation, King Eiders use an income strategy to produce eggs, and I hypothesize that they may retain body reserves for incubation. Body reserves may reflect the residual body condition from the previous winter. I further examined whether females wintering in different regions in the Bering Sea had different rates of nest survival. The northern Bering Sea has a higher benthic biomass and is closer to breeding grounds than winter regions farther south. However, nest survival rates of female King Eiders in northern Alaska did not differ between females that had wintered in the northern or southern Bering Sea. Overall, I found large individual variation in movement and breeding strategies, and little evidence for strong seasonal interactions between winter, spring, and summer. This indicates that King Eiders are a very adaptable species that depend on resources acquired on breeding grounds to a larger extent than previously assumed.
    • King eider wing molt: inferences from stable isotope analyses

      Knoche, Michael J. (2004-12)
      The western North American population of the king eider is thought to have declined by over 50% between 1974 and 1996 without an apparent cause. The non-breeding period of king eiders consists of 80-100% of their annual cycle if not impossible by observation. I used stable carbon and nitrogen isotope values of feathers and muscle to examine the wing molt and migration ecology of king eiders in 2003. Eider primary feathers were isotopically homogenous along the length of the feather, implying invariable diets during wing molt. Captive eiders in their hatch-year did not fractionate nitrogen isotopes, potentially indicating preferential protein allocation associated with growth. Six percent of female eiders sampled molted primary feathers on their breeding grounds, which had not been previously substantiated. Tissue samples from both genders corroborated dietary shifts inherent in switching from a marine to terrestrial diet. Carbon isotopes of feathers from satellite-transmittered males were correlated with longitude of their known wing molt locations indicating that the gradient of carbon isotopes can be used to draw inferences about molt location of eiders.
    • Kuiggluk Speech Community

      Amos-Andrew, Barbara; Marlow, Patrick (2010)
      This thesis explores language shift in the Kuiggluk speech community through interviews, observation, and surveys. Kuiggluk is a Yup'ik community in Southwestern, Alaska that is undergoing language shift from the indigenous language, Yugtun, to English. The interviews examine four mothers and their daughters' speech patterns and their schooling and cultural history. The observations reflect the four girls' speech patterns and their daily conversations. The surveys examine the Kuiggluk youth's speech patterns and goals for Yugtun more broadly.
    • The Kyoto protocol and the Arctic Region: a case study of Finland and Canada

      Shnoro, Reija (2006-08)
      The Kyoto Protocol is part of the international climate change regime. Its objective is to mitigate climate change by reducing greenhouse gas emissions. This thesis uses three criteria derived from regime theory to evaluate the effectiveness of the Protocol: objectives of a regime, the difference a regime makes, and regime evolution. But the Protocol has proven ineffective in both a regional policy framework and in the context of a national and sub-national framework. In this thesis Finland - a member of the European Union - is presented as an example of implementation through a regional framework. Canada - a federal state - provides an example of implementation through a national and sub-national framework. Three categories of analysis are used to evaluate national approaches: interests, institutions, and policies. This thesis concludes that the Kyoto Protocol is not a viable vehicle for policy on greenhouse gas emission reduction, regardless of a member state's institutional structures, due to critical flaws in the Protocol itself in Finland's and Canada's political structures; an over-reliance on flexible (market-based) mechanisms, unrealistic targets, inability to compensate for unanticipated events, and inability to overcome political and economic resistance at the national level.
    • Labelling studies on sesquiterpene lactones and phytosterols of Gaillardia pulchella

      Seaton, Pamela Jo (1977-08)
      The flowering plant, Gaillardia pulchella, contains sesquiterpene lactones which act as anti-tumor agents. Biosynthetic studies were undertaken to elucidate the metabolic pathway to these compounds and to find other potential anti-tumor agents or compounds for structure-activity relationship studies. Compounds which showed incorporation of radioactivity from 2-¹⁴C-mevalonic and 2--¹⁴C-acetic acids were isolated and identified. It was found that incorporation of both 2-¹⁴C-mevalonic and 2--¹⁴C-acetic acids into the sequiterpene lactones was extremely low: less than 0.7 percent of the total plant-contained radioactivity with mevalonic acid and less than 1.5 percent with acetic acid. Incorporation into phytosterols was much higher, approximately 10 percent for both mevalonic acid and acetic acid. The results indicate that sequiterpene lactone biosynthesis is compartmentalized into structures impermeable to exogenously fed mevalonate and acetate.
    • Laboratory investigation of infiltration process of nonnewtonian fluids through porous media in a non-isothermal flow regime for effective remediation of adsorbed contaminants

      Naseer, Fawad; Misra, Debasmita; Metz, Paul; Awoleke, Obadare; Najm, Majdi Abou (2019-12)
      Contamination of soil and groundwater have serious health implications for man and environment. The overall goal of this research is to study a methodology of using nonNewtonian fluids for effective remediation of adsorbed contaminants in porous media under nonisothermal flow regimes. Non-Newtonian fluids (Guar gum and Xanthan gum solutions) provide a high viscous solution at low concentration and these fluids adjust their viscosities with applied shear rate and change in temperature. Adjustment of viscosity with an applied rate of shear is vital for contaminant remediation because non-Newtonian shear thinning fluids can penetrate to low permeability zones in subsurface by decreasing their viscosities due to high shear rates offered by low permeability zones. The application of non-Newtonian shear thinning fluids for contaminant remediation required the improvement in understanding of rheology and how the factors such as concentration, temperature and change in shear rate impacted the rheology of fluids. In order to study the rheology, we studied the changes in rheological characteristics (viscosity and contact angle) of non-Newtonian fluids of different concentrations (i.e., 0.5g/l, 1g/l, 3g/l, 6g/l and 7g/l) at different temperatures ranging from 0 ºC to 30 ºC. OFITE model 900 viscometer and Tantec contact angle meter were used to record the changes in viscosity of fluids for an applied range of shear rate (i.e., 17.02 s⁻¹ to 1021.38 s⁻¹) and contact angles, respectively, for different concentrations of non-Newtonian fluids. Understanding the flow characteristic of non-Newtonian fluids under low temperature conditions could help in developing methods to effectively remediate contaminants from soils. Results of rheological tests manifested an increase in the viscosity of both polymers with concentration and decrease in temperature. Mid (i.e., 3g/l) to high (i.e., 6g/l and 7g/l) concentrations of polymers manifested higher viscosities compared to 0.5g/l for both polymers. Flow of high viscous solutions required more force to pass through a glass-tube-bundle setup which represented a synthetic porous media to study the flow characteristic and effectiveness of Newtonian and non-Newtonian fluids for contaminant remediation. Low concentrations of 0.5g/l were selected for flow and remediation experiments because this concentration can flow through porous media easily without application of force. The 0.5g/l of Xanthan gum and de-ionized water were used to conduct the infiltration experiments to study the flow characteristics of Newtonian and non-Newtonian fluids at 0.6°C, 5°C and 19°C in synthetic porous media. Infiltration depth of both Newtonian and non-Newtonian fluids would decrease with the decrease in temperature because of the change in their properties like dynamic viscosity, density and angle of contact. The result of comparison of Newtonian and non-Newtonian fluids showed water to be more effective in remediating a surrogate adsorbent contaminant (Dichlobenil) from the synthetic porous media at 19°C. This result was counter-intuitive to what we began with as our hypothesis. However, it was also observed later that 0.5 g/l concentration of Guar gum behaved more like a Newtonian fluid and 0.5 g/l concentration of Xanthan gum had not shown strong non-Newtonian behavior compared to higher concentrations of Xanthan gum. Hence more analysis needs to be done to determine what concentration of non-Newtonian fluid should be more effective for remediation.
    • Laboratory studies of gas permeability of frozen soil

      Lin, Qing (2003-08)
      A preliminary investigation on the gas permeability of frozen soil was conducted in this study. A unique low-temperature permeability testing system was designed and developed. Widely accepted standard procedures were followed to prepare soil samples. A number of experiments were conducted in a cold chamber with controlled temperature. The impact of several parameters upon the gas permeability of frozen soil was investigated. The experiment results indicated that among the parameters examined, moisture content had the most significant impact on the gas permeability of frozen soil and the effect of temperature was less significant than that of moisture content. It was also found that there seemed to be a transition zone around 10% of moisture content. With moisture content above this level, the permeability was less sensitive to temperature change, while below this level the permeability was more sensitive to temperature change. Another finding was that the permeability increased when the temperature fell below 20ʻF. In addition, applying loads decreased permeability by 10% to 30% dependent on the setting of other parameters. Some suggestions for improvement of the experiments and future research works were also presented.
    • Lake Area Change In Alaskan National Wildlife Refuges: Magnitude, Mechanisms, And Heterogeneity

      Roach, Jennifer; Griffith, Brad; Harden, Jennifer; Verbyla, David; Jones, Jeremy (2011)
      The objective of this dissertation was to estimate the magnitude and mechanisms of lake area change in Alaskan National Wildlife Refuges. An efficient and objective approach to classifying lake area from Landsat imagery was developed, tested, and used to estimate lake area trends at multiple spatial and temporal scales for ~23,000 lakes in ten study areas. Seven study areas had long-term declines in lake area and five study areas had recent declines. The mean rate of change across study areas was -1.07% per year for the long-term records and -0.80% per year for the recent records. The presence of net declines in lake area suggests that, while there was substantial among-lake heterogeneity in trends at scales of 3-22 km a dynamic equilibrium in lake area may not be present. Net declines in lake area are consistent with increases in length of the unfrozen season, evapotranspiration, and vegetation expansion. A field comparison of paired decreasing and non-decreasing lakes identified terrestrialization (i.e., expansion of floating mats into open water with a potential trajectory towards peatland development) as the mechanism for lake area reduction in shallow lakes and thermokarst as the mechanism for non-decreasing lake area in deeper lakes. Consistent with this, study areas with non-decreasing trends tended to be associated with fine-grained soils that tend to be more susceptible to thermokarst due to their higher ice content and a larger percentage of lakes in zones with thermokarst features compared to study areas with decreasing trends. Study areas with decreasing trends tended to have a larger percentage of lakes in herbaceous wetlands and a smaller mean lake size which may be indicative of shallower lakes and enhanced susceptibility to terrestrialization. Terrestrialization and thermokarst may have been enhanced by recent warming which has both accelerated permafrost thawing and lengthened the unfrozen season. Future research should characterize the relative habitat qualities of decreasing, increasing, and stable lakes for fish and wildlife populations and the ability of the fine-scale heterogeneity in individual lake trends to provide broad-scale system resiliency. Future work should also clarify the effects of terrestrialization on the global carbon balance and radiative forcing.
    • Lake trout (Salvelinus namaycush) otoliths as indicators of past climate patterns and growth in Arctic lakes

      Torvinen, Eric S.; Falke, Jeffrey; Arp, Christopher; Zimmerman, Christian; Sutton, Trent (2017-05)
    • Land cover change on the Seward Peninsula: the use of remote sensing to evaluate the potential influences of climate change on historical vegetation dynamics

      Silapaswan, Cherie Sumitra (2000-12)
      Vegetation on the Seward Peninsula, Alaska, which is characterized by transitions from tundra to boreal forest, may be sensitive to the influences of climate change on disturbance and species composition. To determine the ability to detect decadal-scale structural changes in vegetation, Change Vector Analysis (CVA) techniques were evaluated for Landsat TM imagery of the Seward Peninsula. Scenes were geographically corrected to sub-pixel accuracy and then radiometrically rectified. The CVA results suggest that shrubbiness is increasing on the Seward Peninsula. The CVA detected vegetation change on more than 50% of the burned region on TM imagery for up to nine years following fire. The use of both CVA and unsupervised classification together provided a more powerful interpretation of change than either method alone. This study indicates that CVA may be a valuable tool for the detection of land-cover change in transitional regions between tundra and boreal forest.
    • Landfast sea ice formation and deformation near Barrow, Alaska: variability and implications for ice stability

      Jones, Joshua M.; Hajo, Eicken; Shapiro, Lewis; Hutchings, Jennifer; Weingartner, Thomas (2013-12)
      Climate change in the Arctic is having large and far-reaching effects. Sea ice is declining in annual extent and thinning with a warming of the atmosphere and the ocean. As a result, sea ice dynamic behaviour and processes are undergoing major changes, interacting with socio-economic changes underway in the Arctic. Near Barrow, Alaska, landfast sea ice is an integral part of native lñupiaq culture and impacts the natural resource extraction and maritime industries. Events known as breakouts of the landfast ice, in which stable landfast ice becomes mobile and detaches from the coast, have been occurring more frequently in recent years in northern Alaska. The current study investigates processes contributing to breakout events near Barrow, and environmental conditions related to the detachment of landfast sea ice from the coast. In this study, synoptic scale sea level pressure patterns are classified in an attempt to identify atmospheric preconditioning and drivers of breakout events. An unsupervised classification approach, so called Self-Organizing Maps, is employed to sort daily sea level pressure distributions across the study area into commonly observed patterns. The results did not point to any particular distributions which favored the occurrence of breakouts. Because of the comparatively small number of breakout events tracked at Barrow to date (nine events between 2006 and 2010), continued data collection may still yield data that support a relationship between breakout events and large scale sea level pressure distributions. Two case studies for breakout events in the 2008/09 and 2009/10 ice seasons help identify contributing and controlling factors for shorefast ice fragmentation and detachment. Observational data, primarily from components of the Barrow Sea Ice Observatory, are used to quantify stresses acting upon the landfast ice. The stability of the landfast ice cover is estimated through the calculation of the extent of grounded pressure ridges, which are stabilizing features of landfast ice. Using idealized ridge geometries and convergence derived from velocity fields obtained by coastal radar, effective grounding depths can be calculated. Processes acting to destabilize or precondition the ice cover are also observed. For a medium-severity breakout that occurred on March 24, 2010, the calculated atmospheric and oceanic stresses on the landfast ice overcame the estimated grounding strength of ridge keels, although interaction with rapidly moving pack ice cannot be ruled out as the primary breakout cause. For another medium-severity breakout that took place on February 27, 2009, the landfast ice was preconditioned by reducing the draft of grounded ridge keels, with subsequent detachment from the shore during the next period of oceanic and atmospheric conditions favoring a breakout. For both of these breakouts, in addition to their potential role in destabilizing the landfast ice by overcoming the ridge grounding strength, current and/or wind forcing on the landfast ice were found to be important factors in moving the stationary ice away from shore.
    • Landscape Control Of Thunderstorm Development In Interior Alaska

      Dissing, Dorte; Verbyla, David (2003)
      General Circulation Models suggest a future climate of warmer and possibly drier summers in the boreal forest region, which could change fire regimes in high latitudes. Thunderstorm development is a dominant factor in the continental boreal forest fire regime, through its influence as a fire starting mechanism. Global Climate Change research has identified the land-atmosphere interface as a vital area of a needed research in order to improve our predictions of climate change. This dissertation has focused on the development of thunderstorms and lightning strike activity in a boreal forest region in Interior Alaska and on how the underlying surface can influence their development. I have examined the distributions and correlations between lightning strikes, thunderclouds, thunderstorm indices (CAPE and LI), elevation, and vegetation variables in Alaska. The relationships were examined at scales ranging from the Interior region of the state to individual wildfire burn scars, and at temporal scales ranging from the annual to daily. The objective is to understand the influential factors and processes responsible for thunderstorm development in Alaska, such that we may produce well-founded predictions on future thunderstorm regimes caused by a changing climate. The scale-related studies of this dissertation show that both processes and important variables for development of thunderstorms and lightning activity vary within and between the scales. It appears that on the larger scales, the combined effects of boreal forest and elevation on increased lightning strike activity were more prevalent than at the smallest scale (local). When the scale gets too small for the boundary layer to be affected (<10km), land surface effects on lightning cannot be. My results suggest that the underlying surface (in the form of areal forest coverage and vegetation) has more of an influence on convective development on days with airmass storms than on days with synoptic storms.
    • Landscape modeling of threespine stickleback occurrence in small Southeast Alaska lakes

      Gregovich, Dave (2007-12)
      Although threespine stickleback (Gasterosteus aculeatus L) are known to inhabit a wide range of habitats, their distribution in lakes across Southeast Alaska is not known. Threespine stickleback are an important prey item for many consumers in freshwater ecosystems. Additionally, isolated populations may be genetically unique and thus important from a conservation perspective. This study focused on identifying' landscape factors and models useful in predicting the presence of threespine stickleback in small (0.5-5 ha) lakes of Southeast Alaska. Stickleback occurrence was assessed via snorkeling and minnow trapping in 54 lakes, which were divided into calibration (n=36) and prediction (n=18) data sets. A number of models representing four methodologies-generalized linear models, generalized additive models, classification trees, and artificial neural networks-were built based on the calibration set, cross-validated, and evaluated by prediction to the test set of lakes. Lake elevation, distance from saltwater, and slope of lake outlet stream were the most useful predictors of stickleback occurrence. Results suggest that the likelihood of stickleback presence is highest in low elevation lakes near the coast. Human development and recreational activity also tends to be common in these areas, and so land-use planning should account for the high potential occurrence of threespine stickleback here