• The taphonomy and phylogenetic relationships of the Talkeetna mountains hadrosaur

      Stack, Kevin P. (2012-05)
      The fossil record of hadrosauroids (Ornithopoda, Hadrosauroidea) from the Albian to Santonian is very sparse, with few described North American and Asian taxa compared to the diverse record of Campanian to Maastrichtian hadrosaurids. In 1994, the partial postcranial remains of a hadrosauriform dinosaur were found in the Matanuska Formation of southern Alaska. The Matanuska Formation is a thick succession of Albian¬to Maastrichtian-aged, dominantly marine, sediments deposited in a forearc basin along the actively accreting western North American margin. The Alaskan specimen is assigned a Turonian age based on molluscan biostratigraphy. The skeleton consists of postcranial elements including cervical, dorsal and caudal vertebrae, a partial pectoral girdle, proximal elements of the forelimbs, a partial pelvic girdle, and representative portions of the hindlimbs. This fossil represents the most complete, single skeleton of a dinosaur known from Alaska, and one of the few skeletal remains recovered outside of the North Slope. It is only the second North American Turonian hadrosauroid described, the other being jeyawati rugoculus from New Mexico. This specimen also represents a new taxon of basal hadrosauroid that can be diagnosed by its unique combination of humeral, filial, and femoral characters. A phylogenetic analysis recovers the new taxon nested within a paraphyletic assemblage of non-hadrosaurid hadrosauroids, being more derived than the North American Cenomanian taxa Eolambia and Protohadros but more basal than stratigraphically younger hadrosauroids from Asia, including Tanius, Bactrosaurus, and Gilmoreosaurus. The temporal and geographic occurrence of the Alaskan taxon provides an important new data point for hypotheses of hadrosauroid biogeography in the Late Cretaceous.
    • Targeting Of Her-2 Overexpressing Breast Cancer Cells With Immunoliposomes

      Kullberg, Max P.; Kuhu, Tom; Owens, Jesse (2010)
      The goal of the research described in this thesis is to develop a liposome based drug delivery system which targets Her-2 overexpressing breast tumors with high specificity. Overexpression of the Her-2 receptor occurs in many cancers but is most prevalent in breast tumors, with 20--30 percent of all cases displaying overexpression of the receptor. In addition, Her-2 overexpressing breast tumors are often aggressive and have a high probability of metastasizing. In the research reported here, a drug delivery system has been created that selectively targets Her-2 overexpressing mammary cells by combining three liposomal technologies. First, a Her-2 targeting antibody was conjugated to the outer surface of the liposomes, resulting in highly specific binding and internalization of liposomes into mammary epithelial cells that overexpress Her-2. Second, the liposomes were designed to be thermosensitive, only releasing their encapsulated cargo in response to mild hyperthermia at 42�C. Finally, the liposomes were attached to a pore-forming protein, listeriolysin O (LLO), which compromises the target cell endosome, allowing for drug delivery directly to the cellular cytoplasm. The liposomes delivered a 22-fold higher concentration of fluorescent marker to cells overexpressing Her-2 than to normal cells, demonstrating the delivery system's potential for targeting Her-2 overexpressing tumors. When a cytotoxin, gelonin, was encapsulated within the liposomes, the delivery system selectively targeted and killed Her-2 overexpressing cells in vitro. To further increase specificity for Her-2 overexpressing cells, the concept of a two-component delivery system was explored. This system would require internalization of two different types of liposomes within a cell endosome for effective drug delivery. Experiments using fluorescent markers show that this method greatly increased targeting specificity for Her-2 overexpressing cells.
    • Taxonomy and phylogeny of the Rove beetle genus Phlaeopterus (Coleoptera: staphylinidae: Omaliinae: anthophagini)

      Mullen, Logan J.; Sikes, Derek; Lopez, Andres; Olson, Link (2017-08)
      The rove beetle genus Phlaeopterus contained 15 species prior to this work, which are found in mountainous regions of northwestern North America, and in East Siberia for one species. These beetles can be found in perpetually cold, wet habitats, usually living in close association with permanent or long-lasting alpine snowfields. Very little is known of the life history of Phlaeopterus, but they have been observed on the surface of snowfields mating as well as feeding on windblown arthropods that have become stranded on snowfield's surface. In this thesis, I present a taxonomic revision of the genus Phlaeopterus as well as a phylogeny using Bayesian and maximum likelihood methods with 46 morphological characters and the mitochondrial gene COI. I found discordance between the morphological and molecular phylogenies, as well as between maximum likelihood and Bayesian methods. Phlaeopterus castaneus and Phlaeopterus loganensis, species with distinct morphology but identical COI sequence data, appear to have undergone recent hybridization in the Rocky Mountains where their ranges overlap. I found strong support for the synonymy of the monotypic genus Vellica with Phlaeopterus. Published taxonomic hypotheses were mostly supported and a priori hypotheses received mixed support. Additionally, the genus Phlaeopterus is re-described, a dichotomous key of all species is provided, and eight new species are described. Two of these, Phlaeopterus bakerensis n. sp., and Phlaeopterus olympicus n. sp., are highly endemic snowfield-associated species, and have not been collected since the late 1970s and early 1980s respectively, lending concern to their conservation status.
    • Tectono-thermal history modeling and reservoir simulation study of the Nenana basin, central Alaska: implications for regional tectonics and geologic carbon sequestration

      Dixit, Nilesh C.; Hanks, Catherine; Coakley, Bernard; Ahmadi, Mohabbat; McCarthy, Paul (2017-05)
      Central Interior Alaska is an active tectonic deformation zone highlighted by the complex interactions of active strike-slip fault systems with thrust faults and folds of the Alaska Range fold-and-thrust belt. This region includes the Nenana basin and the adjacent Tanana basin, both of which have significant Tertiary coal-bearing formations and are also promising areas (particularly the Nenana basin) with respect to hydrocarbon exploration and geologic carbon sequestration. I investigate the modern-day crustal architecture of the Nenana and Tanana basins using seismic reflection, aeromagnetic and gravity anomaly data and demonstrate that the basement of both basins shows strong crustal heterogeneity. The Nenana basin is a deep (up to 8 km), narrow transtensional pull-apart basin that is deforming along the left-lateral Minto Flats fault zone. The Tanana basin has a fundamentally different geometry and is a relatively shallow (up to 2 km) asymmetrical foreland basin with its southern, deeper side controlled by the northern foothills of the central Alaska Range. NE-trending strike-slip faults within the Tanana basin are interpreted as a zone of clockwise crustal block rotation. Seismic refection data, well data, fracture data and apatite fission track data further constrain the tectonic evolution and thermal history of the Nenana basin. The Nenana basin experienced four distinct tectonic phases since Late Paleocene time. The basin initiated as a narrow half-graben structure in Late Paleocene with accumulation of greater than 6000 feet of sediments. The basin was then uplifted, resulting in the removal of up to 5000 feet of Late Paleocene sediments in Eocene to Oligocene time. During Middle to Late Miocene time, left lateral strike-slip faulting was superimposed on the existing half-graben system. Transtensional deformation of the basin began in the Pliocene. At present, Miocene and older strata are exposed to temperatures > 60°C in the deeper parts of the Nenana basin. Coals have significant capacity for sequestering anthropogenic CO₂ emissions and offer the benefit of enhanced coal bed methane production that can offset the costs associated with the sequestration processes. In order to do a preliminary assessment of the CO₂ sequestration and coal bed methane production potential of the Nenana basin, I used available surface and subsurface data to build and simulate a reservoir model of subbituminous Healy Creek Formation coals. The petroleum exploration data were also used to estimate the state of subsurface stresses that are critical in modeling the orientation, distribution and flow behavior of natural coal fractures in the basin. The effect of uncertainties within major coal parameters on the total CO₂ sequestration and coal bed methane capacity estimates were evaluated through a series of sensitivity analyses, experimental design methods and fluid flow simulations. Results suggest that the mature, unmineable Healy Creek Formation coals of the Nenana basin can sequester up to 0.41 TCF of CO₂ while producing up to 0.36 TCF of CH₄ at the end of 44-year forecast. However, these volumes are estimates and they are also sensitive to the well type, pattern and cap rock lithology. I used a similar workflow to evaluate the state of in situ stress in the northeastern North Slope province of Alaska. The results show two distinct stress regimes across the northeastern North Slope. The eastern Barrow Arch exhibits both strike-slip and normal stress regimes. Along the northeastern Brooks Range thrust front, an active thrust-fault regime is present at depths up to 6000 ft but changes to a strike-slip stress regime at depths greater than 6000 ft.
    • Temperature index modeling of the Kahiltna Glacier: comparison to multiple field and geodetic mass balance datasets

      Young, Joanna; Arendt, Anthony; Hock, Regine; Motyka, Roman (2013-12)
      Glaciers of Alaska, USA, and Northwestern Canada are shedding mass at one of the highest rates of any mountain glacier system, with significant impact at the global and local scales. Despite advances in satellite and airborne technologies, fully characterizing the temporal evolution of glacier mass change in individual watersheds remains a challenge. Temperature index modeling is an approach that can be used to expand on sparse ground observations, and that can help bridge the gap between regional and individual watershed estimates of the time series of glacier mass change. Here we present a study on temperature index modeling of glacier-wide mass balance for the large Kahiltna Glacier (502 km�_, 270 to 6100 m in elevation) in the Central Alaska Range, using a combination of ground observations and past climate data products. We reproduce mass changes from 1991 to 2011, and assess model performance by comparing our results to several field and remote sensing datasets. First, we compare our results to a 20-year record of mass balance measurements at a National Park Service index site at the glacier's equilibrium line altitude. We find low correlation between index site measurements and modeled glacier-wide balances (R�_ = 0.24), indicating that the index site may not be representative of the glacier-wide mass balance regime. We compare next to glacier-wide mass balances derived from airborne laser altimetry, to assess the model's long-term mass change estimates. We find disagreement between the mean annual balances for 1995 to 2010 (-0.95 �0.49 m w.e. yr����_ from the model versus -0.69 +0.07/-0.08 m w.e. yr����_ from laser altimetry). To validate the laser altimetry methods, we then compare estimates from 1951 to 2011 from laser altimetry and digital elevation model differencing, finding close agreement (-0.48 +0.08/-0.09 m w.e. yr����_ and -0.41 �0.26 m w.e. yr����_, respectively), and lending strength to the laser altimetry centerline extrapolation techniques. We also examine estimates derived from regionally-downscaled satellite gravimetry. While gravimetry likely underestimates long-term mass loss for this glacier (-0.36 �0.13 m w.e. yr����_ for 2003 to 2010), it correlates well to individual modeled annual balances (R�_ = 0.72) and to the time series of mass balance at an ablation stake location (R�_ = 0.81). Given ongoing refinements to gravimetry downscaling and geodetic techniques, our results point to the potential for integrating multiple methods to obtain the most information on subannual and long-term mass changes at the basin scale for remote sites such as the Kahiltna Glacier.
    • Temperature-index modeling of mass balance and runoff in the Valdez glacier catchment in 2012 and 2013

      Davis, Jennifer L.; Arendt, Anthony; Wolken, Gabriel; McCarthy, Paul; Lilijedahl, Anna (2015-05)
      Glaciers play an important role in both storage and generation of runoff within individual watersheds. The Valdez Glacier catchment (342 km²), located in southern Alaska in the Chugach mountains off of Prince William Sound, is characterized by large annual volumes of rain- and snowfall. As Valdez Glacier and other glaciers within the catchment (comprising 58% of the catchment area) continue to melt in a warming climate, it is unclear how the runoff will be affected. Temperature-index modeling is one method used to estimate glacier mass balance and runoff in highly glacierized catchments, and may be suitable for predicting future runoff regimes. In this study, we used a combination of field measurements (air temperature, glacier mass balance, streamflow, and ground-penetrating radar (GPR)-derived snow water equivalent (SWE) from a parallel study) and modeled climate data (PRISM) to a) calibrate a temperature-index model to glacier mass balance in 2012; b) validate the model to laser altimetry; and c) calibrate a temperature-index model to runoff measurements in fall of 2012 and in spring, summer and fall of 2013. We calibrated the snow-radiation coefficient (r_snow), ice-radiation coefficient (r_ice), and melt factor (MF) of the temperature-index model to glacier mass balance measurements from 2012. Using the calibrated- r_snow, r_ice, and MF (i.e. r_snow, r_ice, and MF = 0.20, 0.50 and 4.0, respectively), we calculated 2012 annual glacier mass balance (Ba) at 0.05 ± 0.49 meters water equivalent (m w.eq.). We next validated the model to 2012 laser altimetry annual glacier mass balance estimates (Ba = 0.20 ± 0.6 m w.eq.). We then modeled glacier mass balance in 2013 using r_snow, r_ice, and MF from the 2012 calibration. The model underestimated summer glacier mass balance in 2013, resulting in annual glacier mass balance (Ba = 0.55 m w.eq.) that did not fall within the 2013 laser altimetry annual balance estimate (Ba = -1.15 +0.29/-0.30 m w.eq.). We therefore re-calibrated MF to 2013 laser altimetry measurements, resulting in an annual glacier mass balance (Ba) of -1.10 ± 0.49 m w. eq. We next calibrated the storage constants of the runoff model to hydrographs from mid-September until mid-October 2012, and from May until October 2013, with r_snow, r_ice, and MF set to values from the 2012 glacier mass balance calibration. Total modeled runoff in mid- September until mid-October 2012 was within 3% of measured runoff (E- and lnE- were 0.54 and 0.76, respectively). Modeled runoff in 2013 was calculated to within 5% of 2013 runoff measurements (E- and lnE-values of 0.79 and 0.70, respectively). We next modeled runoff in 2013 using MF from the 2013 glacier mass balance calibration to laser altimetry (i.e. MF = 7.0). The fit of 2013 modeled to measured runoff was reduced (E- and lnE- values of 0.44 and 0.54, respectively), suggesting that additional glacier mass balance measurements are necessary in 2013 in order to properly calibrate the model. Results indicate that glacier melt parameters likely vary inter-annually. Therefore, the temperature-index model is capable of modeling both glacier melt and runoff in a maritime catchment, provided that ablation stake, air temperature, precipitation, and streamflow measurements are available for the simulation period.
    • Temperatures, thermal fluxes and effusion rates associated with the growth of Bezymianny Volcano using spaceborne thermal infrared data

      Steffke, Andrea Marie (2005-08)
      Bezymianny Volcano located on the Kamchatka Peninsula, Russia erupts one to two times annually. Often the eruption pattern follows the same cyclic process from slow growth to dome failure and collapse. These dome processes were analyzed during the Fall 2000 eruption using A VHRR, MODIS, ASTER and Landsat ETM + satellite data and field measurements using a Forward Looking Infrared Radiometer (FLIR). These data have a range of resolutions which provide different levels of information which are compared in this thesis. The satellite data showed an increase in thermal flux up to the collapse of the dome and then a sharp decrease there after. Four phases of activity were identified during the Fall 2000 eruption period; precursory, low-level eruption, explosive eruption and the end of the eruption based on temperatures, thermal fluxes, effusion rates, visual and seismic observations. Integrating these different data sets and measurements provided a useful tool to predict future explosive eruption at Bezymianny Volcano. A comparison of thermal data between sensors with variable resolutions allows a better understanding of volcanic processes at lava domes which improves volcano monitoring and eruption predictions.
    • The temporal and spatial distribution of dissolved and particulate iron over the Gulf of Alaska shelf

      Roberts, Megan Victoria; Aguilar-Islas, Ana M.; Trainor, Thomas P.; Simpson, William (2018-08)
      The Gulf of Alaska (GOA) is a region with contrasting ecosystems where the availability of the essential micronutrient iron (Fe) contributes to the observed productivity. However, knowledge on the temporal and spatial variability of iron species over the GOA shelf is limited. The offshore GOA displays lower annual production and residual nitrate in surface waters throughout the year due to low Fe supply, while high spring production is observed over the shelf due to ample nitrate and Fe supply, but these waters become nitrate limited by mid-summer. Processes promoting the exchange of the Fe rich shelf waters with the nitrate rich offshore GOA waters create favorable conditions for phytoplankton to bloom. Mechanisms for Fe introduction and transport are seasonal freshwater input, alongshore advection from the Alaska Coastal Current eddies, deep wintertime mixing, downwelling, downwelling relaxation, and/or upwelling conditions. Additional Fe sources from subsurface waters and sediment re-suspension can impact Fe distributions. Highly seasonal glacial and river input bring in an abundance of both particulate and dissolved Fe species, which differ in their biological availability. For example, dissolved Fe (DFe) is much more readily available than particulate Fe (PFe). The PFe pool can be separated into a labile fraction, which is potentially transferable to the dissolved phase on time scales relevant to phytoplankton blooms, and a refractory fraction, which is considered biologically unavailable. Seawater samples to determine Fe speciation were collected in spring and early fall of 2013 during three GOA scientific cruises. Trace metal clean procedures were followed during sample collection, processing and analysis. Seawater samples were collected by two methods: 1) Vertical samples were obtained using custom-made samplers (UAF vanes) and filtered offline for PFe analysis; 2) surface samples were obtained by using a towed pump system ("the Fe fish") and filtered in-line for DFe analysis. The PFe fractions of suspended particles were further processed using chemical separation: a) 25 % acetic acid leach with a reducing agent to determine leachable particulate Fe; b) complete digestion of the filter using strong acids to determine refractory particulate Fe. Quantitative determination was by inductively coupled plasma mass spectrometry. Results indicate the broader Western GOA shelf displayed higher average concentrations of total particulate Fe (~121 nM on average) compared to the narrower Southeastern GOA shelf (~18 nM on average). Areas of high glacial input, such as in the vicinity of the Copper River discharge (western side of Kayak Island) and within Prince William Sound near Columbia Glacier, exhibited highly elevated concentrations of total particulate Fe (~430 nM to ~1100 nM). When comparing geographic location, the suspended leachable particulate Fe was higher (~ 22%) over the Southeastern shelf, while the Northern and Western shelf had lower percentage of leachable Fe (11 - 12 %). Over the Southeastern shelf, DFe concentrations were higher in late spring ranging (0.22 - 3.13 nM), while in early fall concentrations were lower (0.07 - 0. 84 nM). Surface water results indicate that there is a significant input of PFe and DFe that occurs in the early fall that extends over much of the Northern shelf and at the inner Western shelf. Variability in downwelling, downwelling relaxation, and upwelling conditions were observed to impact Fe distributions over the Southeastern shelf. These results highlight the impact that the intense environmental variability characteristic of the GOA has on the distribution of Fe species seasonally and geographically.
    • Temporal and spatial distribution of interior Alaska white-fronted geese (Anser albifrons frontalis)

      Webb, Deborah Dawn (2006-05)
      To address the question if white-fronted geese molting in Interior Alaska could be temporally and spatially delineated from the rest of the mid-continent white-fronted goose population, I (1) determined interannual variation in temporal and spatial distribution of geese from Interior Alaska during fall and winter, (2) contrasted temporal and spatial distribution of Interior Alaska geese with Arctic Slope (Alaska) geese, and (3) contrasted migration timing of Interior Alaska geese with Canadian Arctic geese on fall staging areas in prairie Canada. Migration of Interior Alaska geese occurred synchronously and earlier than migration of Arctic Slope geese between Alaska and fall staging grounds in prairie Canada, but was individually highly variable further south on wintering grounds. Spatial distribution of Interior Alaska geese hardly varied between years on fall staging grounds but varied on wintering grounds. Spatial distribution of Interior Alaska geese and Arctic Slope geese differed mostly on fall staging grounds in prairie Canada. Interior Alaska geese staged longer in the study area in prairie Canada than Canadian arctic geese because they arrived earlier and left at the same time. I conclude that delineation of Interior Alaska white-fronted geese is possible on fall staging grounds in prairie Canada, but not on wintering grounds.
    • Temporal and spatial trends of fine particulate matter composition in Fairbanks, Alaska

      Nattinger, Kristian C.; Simpson, William R.; Guerard, Jennifer J.; Cahill, Catherine F. (2016-08)
      Fairbanks, AK experiences extreme winter pollution episodes that result in violations of the Fine Particulate (PM₂.₅) National Ambient Air Quality Standards and pose significant health risks for inhabitants. We analyzed the 2006-2014 wintertime (November 1 to the end of February) PM₂.₅ composition from four sampling sites in the Fairbanks North Star Borough (FNSB) to provide insight into sources and trends. We developed conversions for particulate carbon measurements that were sampled/analyzed with different methods to allow quantitative comparisons. Using these conversions, we found excellent mass closure between PM₂.₅ mass concentration reconstructed from particulate composition and directly measured PM₂.₅ mass concentration. The North Pole Fire Station #3 site (NPFS3) PM₂.₅ mass concentration is nearly double the concentration at other sites in the FNSB and significantly different (t-test on log normalized data, 95% conf.). We observe significant differences (t-test, 95% conf.) in the PM₂.₅ composition between the NPFS3 site and all other sites for most components. Comparison to source profiles indicates that the difference in SO₄²⁻/PM₂.₅ and organic carbon (OC)/PM₂.₅ ratios is attributable to greater use of wood heat in the areas surrounding the NPFS3 site than in Fairbanks. This interpretation is supported by the results of the Home Heating Survey, which found a greater reported use of wood for heat in North Pole than in Fairbanks. Interannual variability is observed in the PM₂.₅ composition. The increase in fuel oil price in 2009 is correlated with an increase in OC/PM₂.₅ ratio and a decrease in the SO₄²⁻/PM₂.₅. The interannual variability of the SO₄²⁻/PM₂.₅ and NH₄⁺/PM₂.₅ ratios are correlated. The particles appear to be neutralized until 2010 when a drop in NH₄⁺ is not accompanied by as large of a drop in anions leaving the particles acidic. The mean sulfur oxidation ratio is 5%, attributable to primary and possible secondary oxidation of SO₂. The results of our analysis supports modeling results that wood smoke contributes a large fraction to the Fairbanks area PM₂.₅. Our work also identified changes in the concentration, composition and spatial distribution of PM₂.₅ that may help air quality managers in identifying effective PM₂.₅ control strategies.
    • Temporal and spatial variability of microclimate and permafrost conditions in Fairbanks Regions, Alaska

      Yershova, Galina E. (2003-10)
      Spatial variability of the climate and permafrost conditions in the Fairbanks region was studied using the temperature measurements at a number of sites in the area of approximately 100x100 km around Fairbanks. The effect of climatic and surface parameters (air temperature, vegetation and snow cover, soil properties including water content) on thermal regime of the ground was studied using the temperature and water content measurements at five sites that represent various landscapes and form the Smith Lake profile. The effect of the topographic gradient and slope aspect on the thermal regime of the ground was studied using the temperature measurements and site moisture characterization along three local topo-sequences in the Fairbanks region. In both considered cases, across various landscapes and along local topo-sequences, the main factor that influences the thermal regime of the ground during the cold period was the snow cover (its depth and duration on the ground) and its combination with the water content on the surface and in the near-surface soils; during the warm period, the main factor was the water content at the surface and in the near surface soils due to the effect of evaporation from the surface that causes cooling of the ground, and the type of local ground surface vegetation.
    • Temporal patterns of migration, molt, and fat storage among high-latitude passerine migrants

      Benson, Anna-Marie (2000-08)
      Aspects of migration, fattening, and molt in trans-continental passerine migrants were examined during spring and autumn migration in Fairbanks, Alaska (64°50’ N, 147°50’ W). From 1992-1998, 25,718 birds of 18 species were banded. Based on median dates of spring and autumn passage, species-level estimates of the duration of breeding range occupation ranged from 48 to 129 days. Adults departed significantly later than immatures in 11 of the 18 species examined and significantly earlier than immatures in only one species, the Alder Flycatcher. Adults had significantly higher fat scores than immatures in most species, but these differences were attributable to the influence of ambient temperatures, length of preceding night, and the time of day the bird was captured. Adults of many species overlapped the final stages of the prebasic molt with autumn migration, and individuals that did so had less stored fat than those that were not molting.
    • Terminus dynamics and deformation of proglacial sediments at the advancing Taku Glacier, Alaska, U.S.A.

      Kuriger, Elsbeth Maria (2005-08)
      Taku Glacier has advanced about 7 km since 1890. The continuing advance is the result of the tidewater-glacier cycle. In the last several decades, the glacier has bulldozed a berm of marine and fluvial sediments from the fjord bottom and produced so-called push moraines. The mobilization of these sediments, which were locally lifted more than 20 m above sea level by 2004, has happened episodically rather than steadily. The last major proglacial sediment deformation was observed in 2001. Since then, most deformation has been localized within some meters of the terminus. Between 2002 and 2004 surface velocities and displacements were measured across the terminus and in the proglacial area. The displacements were highest between March and June and decreased with distance from the terminus. The sediments were presumably deforming internally rather than moving along a basal décollement. A simple model and sensitivity analysis show that major movement along this layer will most likely happen if (1) the glacier steepens its surface topography, (2) the proglacial sediment wedge shortens and steepens its surface slope or (3) the water pressure increases in order to reduce the frictional resistance.
    • Terrestrial invertebrate prey for juvenile chinook salmon: abundance and environmental controls in an Interior Alaska river

      Gutierrez, Laura; Wipfli, Mark S.; Blanchard, Amy L.; Rosenberger, Amanda E. (2011-12)
      Terrestrial prey subsidies can be a key food source for stream fish, but their importance and environmental controls on their abundance have not been widely documented in high latitude ecosystems. This study investigated terrestrial invertebrate prey availability and predation by age-0+ juvenile chinook salmon (Oncorhynchus tshawytscha), overlap between terrestrial infall and drift to diet, and the relationship between diet to stream temperature and discharge in the Chena River, Interior Alaska. Terrestrial infall, drift, and juvenile chinook diet varied widely through the summers (May-September) of 2008 and 2009. Drift was comprised of 33% terrestrial and 67% aquatic invertebrate mass, while juvenile chinook diet contained 19% terrestrial, 80% aquatic, and 1% unidentifiable invertebrate mass. The proportion of terrestrial invertebrate mass consumed increased through summer and, at times, made up to 39% of total diet. Low similarity of invertebrates in diet and infall, and diet and drift suggested that fish were, in part, prey-selective, selecting hymenopterans and chironomid midges (Diptera). In both years, prey mass consumed and discharge varied inversely, but no correlation was found between proportion of terrestrial invertebrates consumed and discharge. However, the two sampling dates with the highest proportion of terrestrial invertebrates consumed occurred shortly after a 60-year flood, indicating that terrestrial invertebrates may be important during rain and associated high water. This study found that, although terrestrial infall and drift are highly variable, terrestrial invertebrates are an important prey resource for rearing chinook salmon in this high latitude riverine system, especially later in the summer.
    • Testing environmental DNA sampling and predictive modeling as means to investigate wood frog (Rana sylvatica) distribution in Alaska and Northern Canada

      Spangler, Mark Anthony; Huettmann, Falk; López, J. Andrés; Barnes, Brian M. (2017-12)
      Global amphibian declines over the past 30+ years have led to a greater awareness of amphibian conservation issues. Few amphibian species occur in northern landscapes, however, and the species that do occur are widely dispersed and at the northern extent of their range. Accordingly, amphibian research is not prioritized in northern landscapes. Deficient monitoring practices have resulted in incomplete distribution knowledge that impedes the management of wood frogs (Rana sylvatica) in Alaska and northern Canada. I developed an environmental DNA detection assay to complement monitoring practices at the northern extent of the wood frog's range. This assay was tested to be species-specific, allowing it to be implemented in areas where wood frogs may co-occur with other amphibian species. It can detect wood frog DNA in environmental samples to a concentration of 1.83 x 10⁻³ pg/μL. I further demonstrate that environmental DNA occurrence data can be used to predict wood frog distribution in the Fairbanks North Star Borough. I combined environmental DNA occurrence data with environmental GIS data and analyzed the resulting dataset with machine learning algorithms to define an ecological niche for the wood frog. This niche, when extrapolated to the landscape, results in a species distribution model that attains 74% predictive accuracy. Lastly, I conducted an environmental DNA mega-transect survey along the Elliot/Dalton Highway corridor in Alaska. I combined the results of this survey with citizen science occurrence data from past and current monitoring projects to create a set of alternative occurrence data. This alternative data was combined with environmental GIS data and analyzed with machine learning algorithms to create a species distribution model that achieves 92% predictive accuracy across Alaska and the Yukon Territory, Canada. These results improve upon prior species distribution models developed for wood frogs in Alaska. They provide deeper insights into potential wood frog distribution at high latitudes and elevations in Alaska, where anecdotal observations have previously been recorded. Adoption and widespread use of an environmental DNA monitoring protocol in under-sampled regions of Alaska and northern Canada will generate larger datasets with wider geographic coverage, leading to models with even higher predictive accuracy. Alternative data, including that obtained from environmental DNA and citizen science monitoring, can boost efforts to further develop baseline knowledge of wood frog occurrence in these areas. Species distribution models generated in this research can help guide these efforts. Increasing knowledge of wood frog distribution may assist conservation managers to designate critical habitat, study climate impacts, and make more informed decisions regarding amphibians in northern landscapes.
    • Testing multispecies coalescent simulators with summary statistics

      Baños Cervantes, Hector Daniel; Allman, Elizabeth; Rhodes, John; Goddard, Scott; McIntyre, Julie; Barry, Ron (2018-12)
      The Multispecies coalescent model (MSC) is increasingly used in phylogenetics to describe the formation of gene trees (depicting the direct ancestral relationships of sampled lineages) within species trees (depicting the branching of species from their common ancestor). A number of MSC simulators have been implemented, and these are often used to test inference methods built on the model. However, it is not clear from the literature that these simulators are always adequately tested. In this project, we formulated tools for testing these simulators and use them to show that of four well-known coalescent simulators, Mesquite, Hybrid-Lambda, SimPhy, and Phybase, only SimPhy performs correctly according to these tests.
    • The 1993-1994 Surge Of Bering Glacier, Alaska Observed With Satellite Synthetic Aperture Radar

      Roush, James Joseph (1996)
      Sequential synthetic aperture radar (SAR) images acquired by the First European Remote Sensing Satellite (ERS-1) were employed for observation of the 1993-'94 surge of Bering Glacier, Alaska. Evidence of accelerated motion became visible in late April 1993. Subsequently the surge front propagated down-glacier at a mean velocity of 90 m/day between 19 May and 25 August, reaching most of the 34 km perimeter of the terminus by shortly after 25 August. The calving terminus then advanced rapidly into proglacial Vitus Lake at a maximum rate, during 9 August to 18 October, of 19 m/day in its central area. The propagating surge front consisted of a distributed region of undulations and bulges on the glacier surface having heights, estimated from SAR data, of 40 to 110 m and widths varying from 0.7 to 1.5 km. The measurements were made using terrain-corrected, geocoded and coregistered images. <p>
    • The anesthetic isoflurane influences baseline firing and disrupts chemosensitivity of 5-HT and GABA raphe neurons

      Johansen, Sara L.; Harris, Michael; Taylor, Barbara; Duffy, Larry (2014-05)
      General anesthetics are widely used in clinical and scientific contexts, but their molecular mechanisms, and how these mechanisms give rise to the state of anesthesia, are poorly understood. We investigated the influence of the volatile anesthetic isoflurane on serotonin (5-hydroxytryptamine; 5-HT) and γ-aminobutyric acid (GABA) synthesizing raphé neurons. These cell types have been proposed as central chemoreceptors, cells that sense changes in arterial CO₂/pH and stimulate respiratory output to regain homeostasis. We tested the hypotheses that isoflurane inhibits 5-HT neuron baseline firing, enhances GABA neuron baseline firing, and disrupts the chemosensitivity of both neuron types. We performed extracellular recordings in the medullary raphé using the unanesthetized in situ perfused brainstem preparation. Subsets of neurons were labeled with biotinamide using the juxtacellular labeling method and immunohistochemically identified by neurotransmitter phenotype. Results indicated that isoflurane inhibited action potential discharge in 5-HT neurons. Isoflurane inhibited action potential discharge in a subset of CO₂-inhibited putative GABA neurons and enhanced action potential discharge in a different subset of these neurons. Isoflurane disrupted the chemosensitivity of both 5-HT and GABA neurons. Disruption of 5-HT and GABA neuron chemosensitivity by isoflurane may contribute to the blunted hypercapnic ventilatory response that is a secondary effect of general anesthesia.
    • The behavioral ecology of Arctic grayling distribution in interior Alaskan streams

      Hughes, Nicholas Farrar (1991)
      During the summer months Arctic grayling in interior Alaskan streams get bigger as you travel from downstream reaches to the headwaters. On a smaller scale, within individual pools, the largest fish holds position in the middle of the current, near the deepest part of the pool, and smaller fish hold positions progressively further downstream or to the side of the pool. The results of this study support the hypothesis that a single process--competition for profitable feeding positions--produces both the whole-stream and within-pool distribution pattern. Field experiments showed that competition for desirable positions is responsible for the distribution patterns adopted by groups of fish sharing a pool, and for the size-gradient of fish over the length of the stream. In both cases large fish excluded smaller ones from the most desirable positions. Modeling work suggested that Arctic grayling locate and rank positions on the basis of profitability. Within pools this conclusion was supported by a close fit between the positions predicted by a foraging model and the positions actually selected by Arctic grayling. Over the length of the whole stream this conclusion was supported by the model's prediction that feeding positions become more profitable as you go upstream.