• Carbonate facies and sequence stratigraphy of the carboniferous Lisburne group, Upper Nanushuk River Region, Central Brooks Range, Alaska

      White, Jesse Garnett (2007-12)
      This study documents the stratigraphy, facies, facies associations, depositional environment, sequence stratigraphy, and conodont biostratigraphy of the upper Nanushuk River section of the Lisburne Group. 1621 meters of Kayak Shale and Lisburne Group rocks were measured and studied for facies analysis. Sixteen lithofacies and eleven microfacies were identified composing six facies assemblages. Facies analysis, stacking patterns, and associations suggest that the Nansushuk River section represents a homoclinal carbonate ramp recording an intertidal (Kayak Shale) and open marine to basin transitional sequence. Facies associations, stacking patterns and marine flooding surfaces helped to delineate major sequence boundaries and maximum flooding surfaces. Six 3rd order stratigraphic sequences have been identified in the Nanushuk River section. The section ranges in age from Osagean to lower Morrowan based on conodont biostratigraphy. The reservoir rock potential of the Nanushuk River section resides primarily in the dolomite of the Wachsmuth Limestone. The remainder of the section is considered 'tight' from a microfacies standpoint. Regionally, this study is important for paleogeographic reconstruction of the Lisburne Group across northern Alaska and adds to the general geologic knowledge of the Lisburne Group by obtaining stratigraphic data from a relatively isolated area in the Brooks Range.
    • Carboniferous Lisburne Group Carbonates Of The Porcupine Lake Valley: Implications For Surface To Subsurface Sequence Stratigraphy, Paleogeography, And Paleoclimatology

      Mcgee, Michelle Marie; Whalen, Michael T. (2004)
      This study utilizes high-resolution stratigraphy and sequence stratigraphy to document the response of the Carboniferous Lisburne Group carbonate platform during a change from greenhouse to icehouse conditions. The Lisburne Group in northern Alaska represents a laterally extensive carbonate ramp deposited on a passive continental margin during a greenhouse to icehouse transition. The Lisburne Group is subdivided into the Mississippian Wachsmuth and Alapah Limestones and Mississippian to Pennsylvanian Wahoo Limestone. I have identified six depositional sequences and corresponding systems tracts within the Lisburne Group based on bounding surfaces, cycle stacking patterns, and lateral lithofacies relationships. The Wachsmuth Limestone (Sequences I and II) is comprised of relatively thick cycles that have a "layer cake" stacking pattern that records minor migration of facies. Cycles in the uppermost Wachsmuth Limestone and the Alapah Limestone (Sequences III and IV) are thick, less "layer cake"-like, have deep water tongues at the base, and record significant migration of facies. Cycles in the uppermost Alapah Limestone and the Wahoo Limestone (Sequences V and VI) are thin, juxtapose deep water over shallow water facies, and record significant migration of facies. An unconformity marked by paleosols and karst features has been documented near the Mississippian-Pennsylvanian boundary in the Wahoo Limestone. I interpret the distinct change in cycle stacking patterns between the Mississippian and Pennsylvanian Lisburne Group to be related to changes in Paleoclimate. I interpret Sequences I through IV to be deposited during a greenhouse and transitional climate; whereas, Sequences V and VI were deposited during an icehouse climate.
    • Caribou migration, subsistence hunting, and user group conflicts in northwest Alaska: a traditional knowledge perspective

      Halas, Gabriela; Kofinas, Gary; Fix, Peter; Joly, Kyle (2015-08)
      Alaska Natives of northwest Alaska are highly dependent on barren-ground caribou (Rangifer tarandus) for meeting their nutritional and cultural needs. The Alaska Native village of Noatak borders the Noatak National Preserve (NNP), an area historically and presently used by Iñupiaq for subsistence caribou hunting and other traditional activities. Interactions between local and non-local caribou hunters were analyzed through the lens of common pool resource theory, which I linked to traditional Iñupiaq management of access and use of resources. This study examined changes in caribou migration and its effect on local caribou hunting success, which have been perceived to be the result of the interaction with non-local hunters and commercial aircraft operators transporting non-locals. Past research, decades old at this point, was undertaken prior to some regulations in place today, such as zoned use areas. To understand the implications of these changes, I documented the perceptions of local hunters by drawing on their traditional ecological knowledge (TEK), using a mixed methods approach to capture information on caribou ecology and human-caribou interactions. Mixed methods included a survey of active hunters, semi-structured participatory mapping interviews with local caribou experts of Noatak, key informant interviews, and participatory observation. Local hunters reported that caribou migration has changed, and there has been a decrease in the population of the region's caribou herd, the Western Arctic Herd (WAH). Hunters also reported that caribou hunting has changed substantially in the last five years, with fewer caribou harvested and hunters adapting to accommodate caribou migration shifts. Local hunters ranked aircraft and non-locals hunters as having the greatest negative impact to caribou migration and local hunting, followed by predation, climate change and habitat change. Noatak hunters perceived that their harvest of caribou is most impacted by non-local activity in the Noatak region. As well, local hunters reported that aircraft are a greater disturbance than on-the-ground non-local hunters. Participatory mapping revealed that use-areas are shared by local and non-local users along the Noatak River corridor, including both inside and outside zoned use areas. Suggestions by respondents for improved caribou management and conflicts with non-locals ranged from reducing non-local activity, working together with non-locals and aircraft operators, improving economic development for Noatak, and teaching youth of the village traditional hunting practices. Findings of this research demonstrate that local hunters have a rich, localized knowledge of human-caribou systems, which can contribute further to understanding of caribou-human interactions and in turn help to inform wildlife management decision-making.
    • Caries differences among Sub-Saharan Africans

      Carter, Fawn; Irish, Joel D.; Clark, Jamie; Hoover, Kara (2014-08)
      Teeth are a vital source of data for interpreting ancient lifestyles because of their high preservation potential and direct association with food. Understanding dental pathologies such as dental caries (cavities), can provide valuable information regarding diet and health. The objective of the present study is to compare caries prevalence among sub-Saharan African populations to determine whether any significant differences exist through space, time, economy, and between the sexes. A few small-scale dental pathology studies have been undertaken on specific populations and regions, but until now none have encompassed the entirety of sub-Saharan Africa from the Late Stone Age through modern times. Data on caries counts and severity from 1963 individuals comprising 44 sub-Saharan samples are compared using Mann-Whitney U and factorial ANOVA statistics. Results suggest: 1) major changes in diet related to widespread movement of people caused a general increase in caries; 2) there is no statistically significant difference in the frequency of caries between males and females; 3) people living in the savanna have more caries because of their dependence on high carbohydrate foods; and 4) subsistence strategy plays a role in caries frequencies. These findings reveal that global trends in caries susceptibility as described by other researchers do not always apply and that each population should be considered in turn.
    • Caries prevalence in ancient Egyptians and Nubians

      Triambelas, Konstantine; Irish, Joel; Hoover, Kara; Clark, Jamie (2014-08)
      This thesis presents an expanded bioarchaeological perspective to quantitative analyses of dental caries in the remains of 1842 ancient Egyptians and Nubians. The skeletal samples from 17 Egyptian and 15 Nubian cemeteries are represented by both sexes, and span a period from 14000 BCE-1450 CE. Considering that a skeletal population of this size has never been previously evaluated for dental caries, this thesis can make a considerable contribution to a better understanding of the variability encountered in dental caries patterns over time, as these are manifested within the bio/cultural/ecological context of the Nile Valley. Dental caries are the decomposition of tooth enamel resulting from the chemical breakdown of dietary carbohydrates by oral bacteria. In archaeological populations, increasing rates of dental caries have been positively correlated with consumption of agriculturally-based cereals such as wheat and barley. Dental caries rates thus provide a reliable indicator of human biocultural transitions to agriculture, as well as information on diet, general oral health, and social organization of the group. In the context of ancient Egypt and Nubia, dental caries frequencies have been previously used to evaluate regional variability in dietary practices, as well differential access to resources based on sex and social class/status. This thesis reevaluates much of the above information using a larger and more statistically-representative sample. Quantitative analyses based on both non-parametric and parametric statistical techniques were used to assess intra- and inter-sample differences in mean tooth caries, mean individual caries, and mean ante mortem tooth loss (AMTL). These variables were compared across samples by region, time period, economic organization, sex, and social status. Results for Egypt were in agreement with previous research showing overall low caries prevalence increasing through time. Significant regional and inter-cemetery differences existed between Lower Egypt and Upper Egypt, as well as between late Dynastic samples and earlier ones. In Nubia, significant differences according to region and sex were shown to exist in the prehistoric/preagricultural component of the study. In contrast with previous findings, Nubian dental caries were higher in the earlier phases and declined during the agriculturally-intensive periods of later Nubian history. The exception to this last finding was the Christian period when both dental caries and AMTL experienced considerable increases.
    • Carpenters daughter

      Osier, Jill N. (2000-05)
      Carpenter's Daughter reveals the construction and reconstruction a woman understands her life to be. Acknowledging the creation of identity through the tools of history, memory, dream, and imagination, it further explores where these worlds converge at different points along the path from child to girl to woman. The poems are equally concerned with dynamics beyond a sense of self--particularly how things come together and come apart. In both the realm of nature and that of human emotion, the speakers are confronted by tenuous connections and surprising holds, moved by the frailties lying beneath solid foundations and the grace witnessed in failing frames. Though several poems use formal patterns of line or stanza, most work in free verse and are driven by narrative, image, or voice. These also provide thematic links throughout the collection, their echoes serving to fully present ideas as well as celebrate sound.
    • Carving Alaska Soapstone

      Eubank, Mary Louise Reed (1968)
    • A case/control analysis and comparison of indoor air quality in Alaskan homes

      Dinakaran, Satish; Johnson, Ron; Naidu, Sathy; Lin, Chuen-Sen; Seifert, Rich (2005-08)
      Indoor Air Quality (IAQ) parameters such as CO, CO₂, relative humidity, temperature, radon, particulate matter, formaldehyde, benzene, toluene, hexane, Total Volatile Organic Compounds (TVOC) and microbial matter were monitored before and after remediation in 36 low-income homes in Alaska (Hooper Bay and Fairbanks). The objective was to see if there was any improvement in IAQ with remediation. Hooper Bay homes had significantly higher levels of CO₂ and relative humidity compared to Fairbanks homes both before and after remediation. There was a general reduction in CO₂ with remediation, although it was not statistically significant. When IAQ in two moderate-income homes in Fairbanks was compared with that in the remediated low-income homes, it was observed that indoor CO₂ levels were affected by ventilation rates and per capita floor area. A single zone model to predict concentration of indoor pollutants was constructed, using steady state and transient mass conservation, to predict, metabolically produced CO₂, and particulate matter when no indoor sources were present. The cost of energy to reduce indoor CO₂ levels in one of the homes by increasing ventilation by either using an exhaust-only system or a Heat Recovery Ventilator (HRV) is discussed.
    • Causes and consequences of coupled crystallization and vesiculation in ascending mafic magmas

      Lindoo, Amanda N.; Larsen, Jessica F.; Freymueller, Jeffrey; Izbekov, Pavel; Trainor, Tom (2017-08)
      Transitions in eruptive style and eruption intensity in mafic magmas are poorly understood. While silicic systems are the most researched and publicized due to their explosive character, mafic volcanoes remain the dominant form of volcanism on the earth. Eruptions are typically effusive, but changes in flow behavior can result in explosive, ash generating episodes. The efficiency of volatiles to degas from an ascending magma greatly influences eruption style. It is well known that volatile exsolution in magmas is a primary driving force for volcanic eruptions, however the roles vesicles and syn-eruptive crystallization play in eruption dynamics are poorly understood. Permeability development, which occurs when gas bubbles within a rising magma form connected pathways, has been suspected to influence eruption style and intensity. Numerous investigations on natural eruptive products, experimental samples, and analog experiments have extended the understanding of permeability development and fragmentation processes. However, these studies have focused on silicic, high viscosity, crystal-poor magmas. Little progress has been made in understanding fragmentation mechanisms in mafic or alkali magmas. Mafic systems involve lower viscosity magmas that often form small crystals, also known as microlites, during ascent. Because the merging of bubbles in magma is mitigated by melt viscosity, it is predicted that permeability development in mafic magma will occur at lower bubble volume fractions than in silicic magma. However, no study has been performed on experimental samples to provide evidence for this hypothesis. Furthermore, it is unknown how microlites affect the degassing process in terms of facilitating or hindering permeability development. This thesis employs experimental petrology to: 1) experimentally observe how melt viscosity alone affects permeability development, 2) Understand the effects of syn-eruptive crystallization in vesiculating mafic magmas and synergizes these results to 3) relate experimental findings to the 2008 eruption of Kasatochi volcano.
    • Causes and consequences of geophagy in snowshoe hares (Lepus americanus), an important generalist herbivore of the boreal forest

      Worker, Suzanne; Kielland, Knut; Barboza, Perry; Ruess, Roger (2013-12)
      Geophagy, the consumption of mineral soil, is believed to have several benefits for herbivores. Soils high in clay are often implicated in the detoxification of plant secondary metabolites. High mineral concentrations in soils may also provide nutrients that are poorly available from plants. Local observers report that snowshoe hares (Lepus americanus) use a lick in the foothills of the Brooks Range, Alaska. Using soil from this lick and other mineral supplements, I conducted a series of feeding trials on captive snowshoe hares fed felt-leaf willow (Salix alaxensis) or a formulated ration to determine whether geophagy resulted in a physiological benefit and, if so, which soil constituents are therapeutic. When fed willow leaves, hares ate more and lost less weight when they had access to soil. Access to soil increased sodium intake and dietary ratios of sodium to potassium in hares fed willow. Soil consumption resulted in higher calcium to phosphorous ratios for both diets. Across diets, higher sodium to potassium and lower calcium to phosphorus ratios corresponded to reduced weight loss. Access to pure calcium carbonate resulted in reduced weight loss in hares fed winter dormant willow twigs, suggesting that carbonates may also be an important component of this lick.
    • Causes and consequences of variable extrafloral nectar secretions in quaking aspen (Populous tremuloides Michx.)

      Newman, Jonathon R.; Wagner, Diane; Doak, Patricia; Green, Thomas (2014-05)
      Extrafloral (EF) nectaries mediate a defensive mutualism in many plant populations, wherein plants attract predatory arthropods by providing nectar rewards. The primary objectives of this study were to identify abiotic and biotic factors that may affect secretion by EF nectaries in quaking aspen (Populus tremuloides Michx.) and to determine how variation in secretion rate affects attractiveness of P. tremuloides ramets to predatory arthropods such as ants. I investigated the effects of water stress, defoliation, and genotype on extrafloral sugar secretions in P. tremuloides and tested how variations in EF sugar quantity affect ant visitation to P. tremuloides ramets in interior Alaska. Additionally, I analyzed P. tremuloides sugar composition from three genotypes. Extrafloral sugar secretions were inducible by defoliation, and the induction response was not inhibited by water stress. Irrespective of defoliation, water stress had a variable effect on sugar secretion rates between genotypes, with one out of four genotypes exhibiting a reduction in secretion rate in response to low water availability. Genotypes differed in secretion rates overall, which could potentially influence defensive levels among clonal stands. Ant visitation to ramets with experimentally increased sugar availability was increased for one of three genotypes in early summer, though in mid-summer ants did not respond to nectar supplementation. There was no effect of nectar reduction on ant visitation in either early or mid-summer trials. Genotypes attracted different average numbers of ants, which may have been a result of intrinsic variation in volatile organic compound emission, EF nectar secretion rates, or nectar composition. Analysis of EF sugar secretions of P. tremuloides using nuclear magnetic resonance spectroscopy revealed that EF nectar tends to be dominated by sucrose over glucose and fructose. This composition may increase attractiveness to mutualistic ant species, which tend to favor sucrose dominated nectar blends. This study expands our knowledge of the sources of variation in EF nectar secretion and their impact in a widespread, ecologically important tree species.
    • Cecal Function In Ptarmigan

      Gasaway, William Clifton (1974)
    • Cenozoic tectono-thermal history of the southern Talkeetna Mountains, Alaska: multiple topographic development drivers through time

      Terhune, Patrick J.; Benowitz, Jeffrey; Freymueller, Jeffrey; Gillis, Robert (2018-08)
      Intraplate mountain ranges can have polyphase topographic development histories reflecting diverse plate boundary conditions. We apply ⁴⁰Ar/³⁹Ar, apatite fission track (AFT) and apatite (U-Th)/He (AHe) geochronology-thermochronology to plutonic and volcanic rocks in the southern Talkeetna Mountains of Alaska to document regional magmatism, rock cooling and inferred exhumation patterns as proxies for the deformation history of this long-lived intraplate mountain range. High-temperature ⁴⁰Ar/³⁹Ar geochronology on muscovite, biotite and K-feldspar from Jurassic granitoids indicates post-emplacement (~158-125 Ma) cooling and Paleocene (~61 Ma) thermal resetting. ⁴⁰Ar/³⁹Ar whole rock volcanic ages and AFT cooling ages in the southern Talkeetna Mountains are predominantly Paleocene-Eocene, suggesting that the Range is partially paleotopography that formed during an earlier tectonic setting. Miocene AHe cooling ages within ~10 km of the Castle Mountain Fault suggest ~2-3 km of vertical displacement that also contributed to mountain building, likely in response to the inboard progression of the subducted Yakutat microplate. Paleocene-Eocene volcanic and exhumation ages across interior southern Alaska north of the Border Ranges Fault System are similar and show no N-S or W-E progressions, suggesting a broadly synchronous and widespread volcanic and exhumation event that conflicts with the proposed diachronous subduction of an active west-east sweeping spreading ridge beneath south-central Alaska. To reconcile this, we propose a new model for the Cenozoic tectonic evolution of southern Alaska. We infer that slab breakoff sub-parallel to the trench and subsequent mantle upwelling drove magmatism, exhumation and rock cooling synchronously across south-central Alaska and played a primary role in the development of the southern Talkeetna Mountains.
    • Central CO2 chemosensitivity in tadpoles: impairment and the role of serotonin

      Audie, Spencer D.; Taylor, Barbara E.; Harris, Michael B.; Duffy, Lawrence K. (2012-05)
      Nicotine and ethanol are known neuroteratogens and prenatal exposure correlates with Sudden Infant Death Syndrome (SIDS), which is thought to result from failure to maintain pH homeostasis through respiratory adjustments. This failed homeostatic control is believed to be serotonergic in origin. In previous studies nicotine or ethanol exposure ablated the robust hypercapnic response of early-stage tadpoles. These findings lead us to question if the ablation occurred through a serotonindependent mechanism. This study investigated the role of serotonin (5- HT) in the nicotine- or ethanol-induced abolishment of the hypercapnic response. We found that toxin-exposed animals were insensitive to hypercapnia and also failed to respond to concomitant exposure to hypercapnia and 8-OH-DPAT, supporting our hypothesis that toxininduced abolishment of the hypercapnic response is mediated by 5-HTia receptors. Immunofluorescence data from brainstem slices of ethanolexposed animals showed a decrease in 5-HTia receptors and the serotonin-synthesizing enzyme tryptophan hydroxylase. In contrast, 3- wk nicotine-exposed animals displayed no significant difference in immunofluorescence for either protein. Taken together the electrophysiological and immunofluorescence data suggest the effects of ethanol or nicotine exposure, which impair the hypercapnic response, include a failure of serotonergic signaling and that this failure is not simply the reflection of a global reduction in serotonin levels.
    • Central Nervous System Regulation Of Metabolic Suppression In Arctic Ground Squirrels

      Jinka, Tulasi Ram; Drew, Kelly L. (2010)
      The main focus of this dissertation is central nervous system regulation of metabolic suppression in hibernating mammals in general, and the Arctic ground squirrel (Urocitellus parryii) as a model for seasonal hibernation. Hibernation is a unique physiological, morphological, and behavioral adaptation to overcome the periods of resource limitation. Metabolic suppression seen in torpor during hibernation has several biomedical applications. A multitude of studies have revealed the role of the central nervous system in regulating hibernation, including a role for neurotransmitters and neuromodulators. Previous studies have shown that the neuromodulator adenosine mediates altered thermoregulation during induction of torpor in facultative hibernators, but it is not clear how adenosine influences torpor in seasonal hibernators. The main focus of the current project was to test the hypothesis that a seasonal change in purinergic signaling is necessary for the onset of spontaneous torpor in the Arctic ground squirrel. My dissertation reports that adenosine meets all of the necessary requirements for an endogenous mediator of torpor in the hibernating Arctic ground squirrel. A progressive increase in sensitivity to adenosine A 1 receptors mediated signaling defines the seasonal transition into the hibernation phenotype. I show that adenosine A1 receptor activation is necessary and sufficient to induce torpor in the Arctic ground squirrel. Glutamate is an excitatory neurotransmitter which is widely studied in hibernation research. My dissertation demonstrates that N-methyl-D-aspartate type glutamate receptors, located in the periphery or circumventricular organs, are involved in inducing arousal from torpor in the hibernating Arctic ground squirrel. This dissertation also presents evidence that dietary restriction sensitizes adenosine A1receptors in rats through an increase in surface expression in thermoregulatory regions of the brain (hypothalamus). This contributes to the decline in body temperature and respiratory rate in animals subjected to a restricted diet, which mimics a torpor-like effect.
    • Ceramide Metabolism Regulates A Neuronal Nadph Oxidase Influencing Neuron Survival During Inflammation

      Barth, Brian M. (2009)
      Inflammation is a major component of acute and chronic pathologies of the central nervous system, including psychiatric disorders. Microglia respond to pathogens, injury, and toxins by secreting inflammatory mediators including pro-inflammatory cytokines in an event known as neuroinflammation. This thesis research investigated a link between neuroinflammation and oxidative stress, and ultimately neurodegeneration. The cytokine tumor necrosis factor alpha was shown to stimulate a neuronal NADPH oxidase (NOX), specifically by stimulating the production of ceramide and ceramide-1-phosphate via Mg 2+-neutral sphingomyelinase (Mg2+-nSMase) and ceramide kinase. Intriguingly, glucosylceramide blocked NOX activation, linking ceramide neutralization directly to a decline in oxidative stress. Most importantly, NOX activity interfered with actin and sphingosine kinase-1 via oxidation, demonstrating a positive and detrimental feedback mechanism that impedes neuronal survival pathways. Interestingly, crude extracts from wild Alaskan bog blueberries showed the ability to interfere with Mg2+-nSMase, demonstrating a specific neuroprotective property of the berry. Altogether, this thesis research defined a key neuronal pathway linking inflammation to oxidative stress via ceramide metabolism, potentially allowing for future therapeutic development to improve neuronal function and survival.
    • Change of heart among aboriginal Canadians toward the Mackenzie Valley Pipeline Project, 1970-2003

      Kirsanova, Galina V. (2004-05)
      The last three decades witnessed an astonishing change of heart among the Mackenzie Valley and Delta's aboriginal groups toward the reemerged Mackenzie Valley Pipeline project and associated industrial development. Vehement confrontation between indigenous residents of the northern Homelands and proponents of a new industrial Frontier has given way to mutually beneficial cooperation. This thesis examines the factors of this attitudinal change. First, the Berger Report and aboriginal testimonies are used to reveal the roots of the previous native opposition to the project, i.e., lack of control, inadequate capacities, and possible threats to subsistence. Next is the analysis of the current aboriginal support of industrial development, particularly anticipated revenues, business and employment opportunities, and the prospect of effective resource co-management, which are ensured by various aboriginal-industrial-governmental agreements, as well as by modem needs of the indigenous societies. This longitudinal analysis leads to the emergence of the factors which have prompted native people to change their attitudes (demographic and cultural changes) and empowered them to undertake the proposed development for the sake of their own sustainability (native legal, political, economic and informational capacity-building). The findings suggest that these same factors could contribute to a similar evolution in other Homeland- Wilderness-Frontier regions.
    • Changes in embryonic development, hatching, and zoeae of snow crab with variation in incubation temperature

      Webb, Joel Benjamin (2005-08)
      The effect of incubation temperature on duration of embryonic development and morphology, weight and energetic content of post-hatch zoeae was described for snow crab, Chionoecetes opilio, from the eastern Bering Sea held at -1, 0, 1, 3, and 6° C in the laboratory from collection to hatch. The mean incubation time increased with decreasing temperature by 32% (113 d) between 6 and -1° C. Extrusion success of females at 6° C was lower versus 0 or 3° C, but the duration of hatching did not vary significantly with incubation temperature. A one-year cycle of embryo incubation was observed, indicating that switching from one to two-year duration of embryo incubation may occur early in development. The energy content and individual weights of post-hatch zoeae were not significantly affected by temperature, indicating that longer incubation periods may not have an energetic cost. The rostro-dorsal length of zoeae incubated at 6° C was smaller than those from cooler temperatures. Conversely, the length of the 3rd abdominal somite increased significantly with decreasing temperature, perhaps serving as an indicator of incubation temperature in field collected zoeae. The consequences of varying incubation temperature appear on post-hatch zoeae appear to be limited between -1° and 6° C.
    • Changes in extreme hydroclimate events in Interior Alaskan boreal forest watersheds

      Bennett, Katrina; Hinzman, Larry; Lindsey, Scott; Hiemstra, Christopher; Walsh, John; Cherry, Jessica (2014-12)
      The high latitude regions of the globe are responding to climate change at unprecedented magnitudes and rates. As the climate warms, extreme hydroclimate events are likely to change more than the mean events, and it is the extreme changes that present a risk to society, the economy and the environment of the north. The subarctic boreal forest is one of the largest ecosystems in the world and is greatly understudied with respect to hydroclimate extremes. Thus, defining a baseline for changing extremes is the first step towards planning and implementing adaptation measures to reduce risk and costs associated with the changing extremes. This thesis focuses on quantitative analysis of extreme events using historical data and future model projections of changing temperature, precipitation and streamflow in the Interior forested region of boreal Alaska. Historically, shifts in the climate have resulted in declining magnitudes of peak flow for snow dominated and glacial Interior Alaskan basins. However, changes are variable and dependent upon watershed topography, permafrost conditions, and glacial extents. Therefore, adjacent basins respond in considerably different ways to the same climate drivers. For example, peak streamflow events in the adjacent Salcha and Chena River basins had different responses to changes in climate. In the higher elevation Salcha basin, maximum streamflow increased as spring temperatures increased but in the lower elevation Chena, winter precipitation was a control on increases in maximum streamflow, while both were influenced by the Pacific Decadal Oscillation. Analysis of hydrologic change must take this variability into account to understand extreme hydroclimate responses and correctly account for process shifts. To examine future changes in peak streamflow, the implementation and parameterization of hydrologic models to simulate hydroclimate extremes is required. In the northern latitudes of the world, there is a sparse observational station network that may be used for evaluation and correction of hydrologic models. This presents a limitation to science in these regions of the globe and has led to a paucity of research results and consequently, a lack of understanding of the hydrology of northern landscapes. Input of observations from remote sensing and the implementation of models that contain parameterizations specific to northern regions (i.e. permafrost) is one aim of this thesis. Remote sensing of snow cover extent, an important indicator of climate change in the north, was positively validated at snow telemetry sites across Interior Alaska. Input of the snow cover extent observations into a hydrologic model used by the Alaska Pacific River Forecast Center for streamflow flood forecasting improved discharge estimates for poorly observed basins, whereas the discharge estimates in basins with good quality river discharge observations improved little. Estimates of snow water equivalent were improved compared to station results and the adaptation of the model parameters indicated that the model is more robust, particularly during the snowmelt period when model simulations are error prone. Use of two independent hydrologic models and multiple global climate models (GCMs) and emission scenarios to simulate changes in future hydroclimate extremes indicated that large regime shifts are projected for snowmelt dominated basins of Interior Alaska. The Chena River basin, nearby Fairbanks, Alaska, is projected to be rainfall dominated by the 2080s, with smaller snowmelt peaks. Return intervals for flooding will increase by one-and-one half to double the flow volume magnitude compared to the historical return interval. Frequency of extreme streamflow events will increase five times the mean increase. These changes in extreme streamflow events necessitate further research on the implications for infrastructure, ecology and economy to constrain risk associated with the projected regime shift in boreal forested watersheds of Interior Alaska.
    • Changes in the spring sea ice concentration in the Bering Sea from 1972-2000 in relation to spotted seal (Phoca largha) pregnancy rates

      Picco, Candace M. (2005-08)
      Spotted seals are most dependent on the seasonal sea ice in the Bering Sea during the spring pupping and mating season. Changes in sea ice characteristics, as related to recent documented changes in climate, may have an effect on spotted seal reproduction. This study investigates the relation between changes in the spatial and temporal patterns of the spring sea ice concentration in the Bering Sea from 1972-2000 to changes in the pregnancy rates of the spotted seal (Phoca largha). Multinomial time-series regressions were used to determine the influence of different climatic variables on the sea ice concentration. Different statistical methods were used to compare the ice conditions of defined regions in the Bering Sea and spotted seal pregnancy rates among 20 years from 1964- 2003. The results showed no definitive patterns relating the monthly climatic variables and sea ice concentration averages; however, noticeable trends in sea ice were found. The variability of the seal pregnancy rates coincided with changes in the Bering Sea ecosystem and ice concentration. This study demonstrated that seal pregnancy rates and sea ice concentration varied temporally and spatially, the direct causality of these variations was uncertain.