Now showing items 414-433 of 3496

• #### Calcareous fen vegetation and ecology and the disjunct Betula glandulosa in Southeastern Alaska

Calcareous fens are rare within southeastern Alaska due to their unique geochemical setting, as are the plant communities produced by these environs. On a global scale these wetland types have been identified as valuable for their biodiversity and have received special protection. The first objective of this research was to characterize the floristics and hydrogeochemistry of a subset of calcareous fens on Chichagof Island in the northern Alexander Archipelago through intensive sampling within each site. Multivariate analyses were used to describe these wetland systems. The second objective of this study included investigating whether or not the disjunct Betula glandulosa (dwarf birch) population was restricted to its current site. B. glandulosa is a habitat generalist in its known range; however, it is found in only one location within the Alexander Archipelago. Germination and seedling transplant experiments were conducted that tested for the effects of site, competition, and the interaction between site and competition. In this manner a subset of calcareous fens in the region was described and abiotic parameters associated with B. glandulosa evaluated. Obtaining baseline information and understanding mechanisms behind these sources of regional biodiversity are important for monitoring purposes and detecting disturbance effects
• #### Calibration of an on-line analyzer using neural network modeling

The goal of the project was to predict the ash content of raw coal in real time using the Americium-137 and Cesium-241 scintillation counts from an on-line analyzer. Rather than regression methods (that are current industrial practice), neural networks were used to map the scintillation counts to percentage ash. Quick stop training was used to prevent overfitting The noise and sparseness of the data required that the training, calibration and prediction subsets are statistically similar to each other. Therefore, Kohonen networks were first used to detect the features present in the data set. Three subsets were then built such that they had representative members from each feature. Neural network models were developed for the screened coal, the unscreened coal and the combined data respectively. The results show that the performance of the combined model was comparable to the performance with two different models for the screened and unscreened data. Due to the variance in the sample data, the neural networks (screened, unscreened and combined) did not predict individual samples well. The network predictions were, however, accurate on the average. Compared to the common regression approach, neural network modeling demonstrated much better performance in ash prediction based on certain criteria.
• #### Calibration of microbolometer infrared cameras for measuring volcanic ash mass loading

Small spacecraft with thermal infrared (TIR) imaging capabilities are needed to detect dangerous levels of volcanic ash that can severely damage jet aircraft engines and must be avoided. Grounding aircraft after a volcanic eruption may cost the airlines millions of dollars per day, while accurate knowledge of volcanic ash density might allow for safely routing aircraft around dangerous levels of volcanic ash. There are currently limited numbers of satellites with TIR imaging capabilities so the elapsed time between revisits can be large, and these instruments can only resolve total mass loading along the line-of-sight. Multiple small satellites could allow for decreased revisit times as well as multiple viewing angles to reveal the three-dimensional structure of the ash cloud through stereoscopic techniques. This paper presents the design and laboratory evaluation of a TIR imaging system that is designed to fit within the resource constraints of a multi-unit CubeSat to detect volcanic ash mass loading. The laboratory prototype of this TIR imaging system uses a commercial off-theshelf (COTS) camera with an uncooled microbolometer sensor, two narrowband filters, a black body source and a custom filter wheel. The infrared imaging system detects the difference in attenuation of volcanic ash at 11 μm and 12 μm by measuring the brightness temperature at each band. The brightness temperature difference method is used to measure the column mass loading. Multi-aspect images and stereoscopic techniques are needed to estimate the mass density from the mass loading, which is the measured mass per unit area. Laboratory measurements are used to characterize the noise level and thermal stability of the sensor. A calibration technique is developed to compensate for sensor temperature drift. The detection threshold of volcanic ash density of this TIR imaging system is found to be from 0.35 mg/m3 to 26 mg/m3 for ash clouds that have thickness of 1 km, while ash cloud densities greater than 2.0 mg/m3 are considered dangerous to aircraft. This analysis demonstrates that a TIR imaging system for determining whether the volcanic ash density is dangerous for aircraft is feasible for multi-unit Cubesat platforms.
• #### Calving ground habitat selection: Teshekpuk Lake and Western Arctic caribou herds

Barren-ground caribou (Rangifer tarandus granti) exhibit relative fidelity to calving grounds each spring. The Western Arctic Herd (WAH) and Teshekpuk Lake Herd (TLH) calve separately on Alaska's north slope, each selective of the dominant vegetation type. The WAH consumed mostly sedges, though the TLH diet varied. Despite differing snow conditions between the calving grounds, both herds were selective of the lowest snow cover class. Rugged terrain was avoided by both herds. While the TLH selected a high rate of increase in biomass, the WAH selected high biomass at calving and at peak lactation. Climate trends (1985-2001) were variable. There was a warming trend on the WAH calving ground, though no significant trends were present on the TLH calving ground, as expressed by median NDVI on 21 June. These herds have similar winter ranges and population trends, yet they differ in respect to habitat composition, selection and climate patterns during calving.
• #### Can I tell you what really happened?: learning to make decisions in response to indigenous student voice in a high school language arts classroom

This study focuses on engaging high school students in reading and the decisions I make to sustain that engagement. I learned that one way to enhance the engagement in my classroom is to listen to my students' stories and to incorporate culturally relevant texts. All of the students in this study were previously in our school's language intervention program: Read 180. While teaching this intervention-based class, I noticed this class was a behavior management nightmare. The students' challenging behavior led me to question the intervention program's ability to sustain my students' engagement through the prescribed texts. This study aims to describe my observations in a 10th grade Language Arts II class in Chefornak, Alaska. Specifically, this thesis describes my findings and analysis as it relates to how students show engagement and how I make (and revise) decisions in response to my students' voices. I used teacher action research (TAR) to research the events in my classroom. During an 11-week period, I collected audio recordings, student work samples, and teacher action research journal entries. At the end of the research, I also wrote memos about the data. I used constructive grounded theory (CGT) to make sense of the story the data tells and to see what kind of patterns were present. This research is important to me because it helps me to understand the weaknesses and the strengths in my own instructional planning as well as how I interpret students' participation in class. After this research, I am convinced that learning outcomes are preceded by learner engagement, and that learner engagement is complex.
• #### Can tax policy change exploration levels? A case of Alaska oil legislation.

This thesis applies modern Autoregressive Distributed Lag modeling techniques to estimate the effects of oil tax policy in the case of the 2007 ACES legislation on exploratory drilling within Alaska. This analysis uses recently released public data to examine the period of 1986 to 2013 in quarterly intervals which includes all periods in which ACES was in place. While this subject has become a popular subject of debate within the state and industry, no similar statistical analysis has been conducted to date. According to the results, ACES had a significantly negative and lasting effect on exploration levels while it was in effect. The oil price and interest rate are also found to be important variables in characterizing exploration activity.
• #### Can We Remain Yup'ik In These Contemporary Times? A Conversation Of Three Yugtun-Speaking Mothers

The Yup'ik people of southwestern Alaska are experiencing language shift from Yugtun to English. This study is a conversation between three Yugtun speaking mothers who are trying to understand this shift and wondering if they can maintain their identity, and that of their children, in this changing world. The study takes place in the village of Kuiggluk. Data collection included a research journal and focus group discussions. In this study, I have tried to paint a picture of who we are as Yup'ik mothers in our contemporary lives. Qayaruaq, Mikngayaq and I carry with us our own mothers' teachings, while at the same time we face different situations in school and schooling. Through our discussions we sought to understand the reasons for language loss/shift -- a shift that seems to be driving us away from our culture.
• #### Canenermiut lifeways and worldview and western fish and wildlife management

The Canenermiut inter-generational worldview embodies the proper use and conservation of the resources necessary to sustain life from time immemorial. The classical Yupiaq conservation ethics in the utilization of subsistence resources are well established and practiced to this day by Canenermiut that is geared to the survival of their culture and community. When western fish and wildlife managers promulgate regulations from urban areas of Alaska on the taking of subsistence resources in rural Alaska they often find out that rural residents such as the Canenermiut ... are unwilling to follow the regulations. Caneneq is a coastal area between Kusquqvak (Kuskokwim) Bay up to Qaluyaaq (Nelson Island). Canenermiut is made up of two Yupiaq words, Caneneq as defined earlier and the suffix miut is a Yup'ik word defined as occupant of that geographic area or a place. The people from these villages see the imposition of the western precepts of fish and wildlife management systems as efforts by outsiders to control their way of life. They see this effort as inconsistent with their worldview of how a human should fit within the creation of a higher being. These people do not participate in the formulation of public policies or the promulgation of the regulations that affect their lives and as a consequence do not have a sense of ownership of them. The Canenermiut worldviews are fundamentally different from the worldview of the people of European origin who brought with them concepts of lifeways foreign to Alaska's indigenous people. The author of this thesis is one of Canenermiut from the Native Village of Kipnuk, who was raised by his parents the traditional Yupiaq way of life and taught by his uncle the art of hunting and fishing. He is also one who was also educated in schools of the dominant western society. As one of many other Alaska Native children who were subjected to the assimilation effort of the United States government in the image of the Other, the author is very cognizant of both the Other's lifeways and the classical Yupiaq lifeways ... The author having lived in both worlds, the world of Canenermiut in the Native Village of Kipnuk and in Anchorage will attempt to articulate the major components of Canenermiut worldview. This is a worldview that western fish and wildlife managers do not understand but ones that may help in enhancing the conservation and utilization of these subsistence resources. Secondly, the author will attempt to articulate the degree of the paradigm shift in the Canenermiut indigenous value system that has occurred among this generation. The desire of the Canenermiut to retain their cultural value system and to control their destiny is affirmed by the author. In addition, as the precepts of fish and wildlife management systems are accepted over time by Alaska Native people outside of the geographic area of Caneneq, the Canenermiut do not want to be left behind and have a strong desire to- participate in these management systems.
• #### Capacitance measurements of bulk salinity and brine movement in first-year sea ice

Sea ice is an important component of the global climate system, as it changes the properties of the ocean-atmosphere interface. Understanding sea ice requires detailed knowledge of its temperature and bulk salinity. To measure these attributes using non-destructive in-situ techniques, instruments were frozen into first-year sea ice, and analysed jointly with ice-core, mass balance and climate data. The bulk salinity of the ice is calculated from measurements of temperature and complex dielectric permittivity at 50 MHz in landfast ice in McMurdo Sound, Antarctica, the Chukchi Sea, Alaska, and in an outdoor tank experiment in Fairbanks, Alaska. A simple relation for estimating brine volume fraction and bulk salinity in columnar, bubble-free ice from the real part of the complex dielectric permittivity was derived. For relative brine volumes below 50-70 % the error in the derived bulk salinity was below 15%. The observed brine movement events are analyzed. The data clearly indicate the extent and impact of brine movement on ice temperature and salinity. The analysis of a drainage event recorded by both the temperature and dielectric permittivity probe provided insight into gravity drainage of brine driven by a large brine reservoir in the freeboard layer.
• #### CARBON AND NITROGEN ASSIMILATION IN THE CLAMS NUCULANA RADIATA AND MACOMA MOESTA FROM THE BERING SEA

The predicted climate-induced reduction in sea ice presence in the Bering Sea could impact benthic trophic interactions; however, species-specific consumer dependence on ice algal production is largely unknown. My objective was to track feeding in the benthic clams, Nuculana radiata and Macoma moesta, using stable carbon and nitrogen isotopes. Nuculana radiata had slow isotopic assimilation rates, with lipids taking up isotope markers fastest and muscle tissue the slowest. Lipids may thus be particularly suitable to track the immediate ingestion of sea ice algal export in benthic consumers. When isotopically enriched food was added to natural sediment cores, N. radiata assimilated 60% less of the isotope markers than when feeding on algal food in isolation. Possibly, this difference is related to the ingestion of other, naturally present food sources in the sediment. Macoma moesta showed 30% higher isotopic assimilation compared to N. radiata in sediment cores. I suggest that differing feeding behaviors between the species provide differential access to the sedimented algal food. Based on these results, N. radiata is likely better able to utilize food sources buried in the sediment and may be more competitive over M. moesta under conditions of reduced ice algal production in the northern Bering Sea.
• #### Carbon And Nitrogen Flows In Zero -Water Exchange Shrimp Culture: Inferences Using Stable Isotope Tracers

Nutrient and energy flow in cultures of Pacific White Shrimp, Litopenaeus vannamei, were examined in zero-water exchange, 1200--1300 L mesocosms at the Oceanic Institute (OI), Waimanalo, Hawaii. A technique was developed for monitoring shrimp use of formulated feeds through the addition of stable isotopically labeled nutrients to the feed ingredients. Crystalline amino acid compounds were ineffective as labels due to their rapid dissolution in the tank water with feed pellet break-up. Labels which were 'packaged' as algal cells prior to addition to the feed pellets were more effectively incorporated into shrimp tissues than crystalline label (approximately 27% versus 8% for crystalline label). The 'packaged' label technique was also used to test soluble proteins from pollock processing wastes (stickwater) as a feeding stimulant for Litopenaeus vannamei. Indoor controlled condition experiments and outdoor experiments with natural pond biota compared stickwater amended feed to squid liver powder amended feed for growth and assimilation by the shrimp. Initial results indicated that pollock processing by-products might function as a feeding stimulant in shrimp aquaculture. The addition of 15N-ammonium to outdoor shrimp tanks showed that natural tank production contributed significantly to shrimp growth requirements providing between 17 and 77% of the growth nitrogen. When labeled ammonium was added to black covered tanks, shrimp had slower growth rates (0.5 g/wk as compared to 0.7 g/wk for uncovered ammonium addition tanks) but significant uptake of this label, with a tank biota contributing 23%. This finding supported a bacterial role in shrimp nutrition that will require further study. Isotopic analysis of individual amino acids in shrimp muscle from outdoor tanks with and without added 15N-ammonium further established the role of tank natural populations to shrimp nutrition. Rapid increases in delta 15N for threonine one day after label addition suggested an increased requirement for this essential amino acid. Further identification of the contribution of tank biota to shrimp amino acid profiles will require profiles of the delta 15N of specific amino acids for suspended particulate organic matter.
• #### Carbon And Nitrogen Isotope Ratios In Bowhead Whales (Balaena Mysticetus) And Their Zooplankton Prey As Indicators Of Feeding Strategy And Environmental Change.

This study details regional, seasonal and inter-annual differences in $\delta\sp{13}$C and $\delta\sp{15}$N of zooplankton in the Bering and Chukchi Seas. These isotopic variations were correlated with inter-annual and long-term variations in $\delta\sp{13}$C and $\delta\sp{15}$N of bowhead whale baleen.<p> Statistical analyses indicate significant $\sp{13}$C-enrichment in Bering/Chukchi seas zooplankton relative to Beaufort Sea zooplankton, supporting the observed trends of $\sp{13}$C-depletion at higher latitudes and enrichment at lower latitudes. Bering/Chukchi seas zooplankton show a weak trend in $\sp{13}$C-depletion between 1987-1990, possibly due to inter-annual environmental changes affecting phytoplankton $\delta\sp{13}$C. The $\delta\sp{13}$C of baleen produced in fall/winter months is inversely correlated to sea surface temperature trends in the Bering Sea. Long-term changes in baleen $\delta\sp{13}$C may be helpful in assessing past climatic change.<p> The observed $\delta\sp{15}$N oscillations in baleen may be due to changes in trophic level of prey between seasonal feeding grounds or from physiological cycles in the bowhead whale. <p>
• #### Carbon and nitrogen uptake dynamics during 1997 and 1998 anomalous conditions in the Bering Sea

During 1997 and 1998, unusual physical conditions caused dramatic changes in the regional oceanic environment and function of the southeastern Bering Sea ecosystem. The changes in ecosystem function were examined using ¹³C and ¹⁵N tracer techniques. In 1997, unusually clear and calm conditions allowed an ice-related early bloom over the middle shelf of the southeastern Bering Sea and resulted in nitrate uptake below the pycnocline. In 1998, the duration of phytoplankton growth was extended by warm temperatures and frequent storms that resulted in slow growth of phytoplankton and prevented rapid utilization of nitrate over the shelf. In coccolithophorid bloom regions, ammonium concentrations were high (>3 uM), while nitrate concentrations had a larger range (O.1-10.8 uM). Nitrate utilization rates, which estimate 'new' production, were similar for both years and were somewhate greater (ca. 30%) than those observed during the 70's and 80's PROBES studies. The fate of primary production may have differed in 1997 and 1998.
• #### Carbon biogeochemistry of the eastern Bering Sea shelf

The uptake of anthropogenic carbon dioxide (CO₂) has caused perturbations to marine biogeochemistry in recent years, including decreasing ocean pH and carbonate mineral saturation states (Ω). Collectively termed ocean acidification (OA), these conditions hinder the growth of calcium carbonate shells and effectively reduce habitat for some marine calcifiers. Given that the Bering Sea is one of the world's most productive marine ecosystems and supports both commercial fishing industries and subsistence communities, it is integral to understand its susceptibility to OA. Here, new observations of the organic and inorganic carbon systems are used to identify mechanisms leading to CO₂ accumulation and sub-regional enhancement of vulnerability to OA processes. Chapter 1 describes the state of knowledge of OA in this area, highlighting two regions where low Ω conditions are consistently observed: near the coast, and over the northern shelf. Chapter 2 describes net heterotrophic processes near the coast, in conjunction with low bottom water Ω. Chapter 3 examines this heterotrophy in more detail, showing that focused deposition of organic matter and its subsequent respiration. Chapters 4 and 5 focus on very low Ω values observed over the northern shelf. In combination with natural respiration processes, anthropogenic CO₂ was shown to cause low Ω and seasonal dissolution of carbonate minerals in Chapter 4. Chapter 5 illustrates how sea ice cover inhibits the flux of CO₂ from the surface ocean to the atmosphere, which raises the inventory of CO₂ in the water column. These results are synthesized in Chapter 6. Low-Ω conditions and areas of carbonate mineral dissolution will continue to expand as anthropogenic CO₂ accumulates in shelf waters in the coming decades, further reducing viable habitat for key calcifiers. Model projections of future surface water conditions indicate that average Ω over the Bering Sea shelf will drop below the observed natural variability by 2100, with average conditions favoring carbonate mineral dissolution in surface waters by 2150. Presently, episodic events will cause regions of the Bering Sea to be undersaturated in Ω, which could have significant and cascading impacts throughout the Pacific-Arctic region.
• #### Carbon Cycling In Three Mature Black Spruce ( Picea Mariana [Mill.] B.S.P.) Forests In Interior Alaska

Climate warming in high latitudes is expected to alter the carbon cycle of the boreal forest. Warming will likely increase the rate of organic matter decomposition and microbial respiration. Faster organic matter decomposition should increase plant available nutrients and stimulate plant growth. I examined these predicted relationships between C cycle components in three similar black spruce forests (Picea mariana [Mill] B.S.P) near Fairbanks, Alaska, that differed in soil environment and in-situ decomposition. As predicted, greater in-situ decomposition rates corresponded to greater microbial respiration and black spruce aboveground growth. However root and soil respiration were both greater at the site where decomposition was slowest, indicating greater C allocation to root processes with slower decomposition. It is unclear what environmental factor controls spruce allocation. Low temperature or moisture could cause spruce to increase belowground allocation because slower decomposition leads to low N availability, but foliar N concentration was similar across sites and root N concentration greater at the slow decomposition site. The foliar isotopic composition of 13C indicated soil moisture was lower at the site with greater root and soil respiration. From a literature review of mature black spruce forests, it appears drier (e.g. Alaska) regions of the boreal forest have greater soil respiration because of greater black spruce C allocation belowground. Organic matter characteristics identified with pyrolysis gas chromatography-mass spectrometry correlated with microbial processes, but organic matter chemistry less influenced C and N mineralization than did temperature. Also, differences among sites in C and net N mineralization rates were few and difficult to explain from soil characteristics. Warming had a greater influence on C and N mineralization than the mediatory effect of soil organic matter chemistry. In this study, spruce root C allocation varied more among the three stands than other ecosystem components of C cycling. Spruce root growth most affected the annual C balance by controlling forest floor C accumulation, which was remarkably sensitive to root severing. Predicting the response of black spruce to climate change will require an understanding of how spruce C allocation responds to available moisture and soil temperature.
• #### Carbon exchange and permafrost collapse: implications for a changing climate

With a warmer climate, the wetlands of Interior Alaska may experience more frequent or extensive stand-replacing fires and permafrost degradation. This, in turn may change the primary factors controlling carbon emissions. I measured carbon exchange along a moisture transect from the center of a sphagnum-dominated bog into a burned forest (2001 Survey Line Fire) on the Tanana River Floodplain. Both the bog and the surrounding burn were sinks for CO₂, and the bog was a CH₄ source in the abnormally dry summer of 2004. Thermokarst and subsiding soils were observed on the margin of the bog in the three years since the fire, increasing the anaerobic portion of the soil landscape. I observed the greatest variation in carbon fluxes in this portion of the transect. I conclude that permafrost collapse is altering the pattern of emissions from this landscape. I tracked historical changes in vegetation, hydrology and fire at this site through macrofossil, charcoal and diatom analysis of peat cores. The paleoecological record suggests that fire mediates permafrost collapse in this system. This study indicates that future changes in temperature and precipitation will alter carbon cycling and vegetation patterns across this boreal landscape.
• #### Carbon flux and particle-associated microbial remineralization rates in the northern Bering and southern Chukchi seas

It has been hypothesized that climate change will reduce the strength and episodic nature of vernal phytoplankton blooms, increase heterotrophy of microbes and zooplankton, and weaken the tight coupling between pelagic and benthic production that is characteristic of Arctic continental shelves. As a part of the Arctic Shelf Growth, Advection, Respiration, and Deposition rates measurement (ASGARD) project, I quantified sinking particle fluxes and incubated sinking particles to measure the rate of microbial respiration associated with those particles. These measurements were used to characterize the strength of the pelagic-benthic connection. After a record-breaking year of warm temperatures and low-ice conditions in the northern Bering and southern Chukchi Seas, we observed massive vernal fluxes of sinking particulate organic carbon, ranking amongst the highest observed in the global oceans. Moreover, low rates of particle-associated microbial respiration indicate negligible recycling of sinking organic matter within the water column. These results suggest that the strength of the biological carbon pump may be maintained or enhanced in a warming Arctic, supporting strong benthic and upper trophic level productivity and carbon export.
• #### Carbon isotopic composition of polycyclic aromatic hydrocarbons and their weathering in Kachemak Bay sediment

Identification of sources of polycyclic aromatic hydrocarbons (PAH) in sediments is an important step in reducing anthropogenic contamination. Identifications based solely on the composition of PAH can be confounded by compositional changes during weathering and biodegradation. Stable isotopic composition of individual PAH offer a source marker that may be less susceptible to alteration. The [alpha]¹³C values of PAH in major potential sources to the Kachemak Bay area were analyzed. To determine the stability of the [alpha]¹³C values of PAH in crude and diesel oil, microbial degradation experiments using sediment from the Kachemak Bay, Alaska, area were conducted over a one-year period. The impact of weathering on the isotopic composition of North Slope crude oil and diesel oil was also examined over a five-week period in aquaria with Macoma balthica, an intertidal bivalve. For both degradation experiments, PAH concentrations decreased and their composition changed, but the [alpha]¹³C values of individual PAHs remained stable. Hence, [alpha]¹³C values of individual PAHs have excellent potential as a relatively stable indicator of their sources. Based on isotopic and compositional data, the PAH in Kachemak Bay sediments appear to have several sources.