Browsing by Subject "Alaska"
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Item Characterizing and Modeling Arctic Shrub Expansion on the North Slope of Alaska, USA(2014-07-30) Naito, Adam TakashiShrub expansion is one of the most recognized components of terrestrial Arctic change and has been documented in studies involving fine-scale experimental manipulations or broad-scale satellite remote sensing. The characteristics and drivers of this phenomenon at the landscape scale, however, are understudied. The motivation of this dissertation was to develop an improved understanding of the historic spatial characteristics of shrub expansion on the North Slope of Alaska and its environmental drivers at this landscape scale. This work has three objectives, which include: 1) mapping and quantifying historic shrub expansion patterns; 2) examining a relationship between shrub expansion and its hydrological controls; and 3) designing and implementing a spatially-explicit simulation model to develop hypotheses regarding the landscape-scale drivers of shrub expansion (i.e., modes of reproduction, hydrological constraints, and their interactions). Shrubs maps were generated from semi-automated classification of historic vertical aerial photographs and contemporary high-resolution satellite imagery within a GIS. The spatial patterns of historic shrub expansion were quantified using FRAGSTATS and the multi-scale information fractal dimension. Relationships between shrub expansion and local hydrology was determined statistically through associations between areas that gained shrub cover and topographic wetness index values derived from a digital elevation model. The contribution of shrub reproductive characteristics was determined by developing a C#-based spatially-explicit simulation model that simulates clonal and sexual reproduction of shrubs. The reproductive mode(s) producing spatial patterns most similar to the observed patterns was determined through principal components analyses. Results from this work suggest that: 1) the shrub-tundra ecotone within river valleys on the North Slope is has either initiated or completed a phase transition from tundra to shrubland; 2) shrub development is promoted in areas where the potential for water accumulation or throughflow is higher; and 3) vegetative reproduction appears to have been dominant mode of reproduction . Considering our current understanding of the fine-scale relationships between shrub expansion and hydrology, surface energy balances, and C and nutrient cycling, continued expansion may have considerable implications for circumpolar tundra ecosystems. These findings will facilitate the development of improved projections of the structure and function of these ecosystems and their feedbacks to climate change.Item Cumulative effects assessment and sustainable development under the National Environmental Policy Act(2004-12) Senner, Robert Glenn; Ward, Peter M., 1951-This dissertation presents a clear and systematic method for conducting cumulative effects assessments in the United States in a manner consistent with the 1997 guidelines of the President's Council on Environmental Quality and the 1999 guidance of the U.S. Environmental Protection Agency's Office of Federal Activities. This method has been developed in a collaborative process with federal and State of Alaska regulatory agency scrutiny during the renewal of the federal and state right-of-way leases for the Trans Alaska Pipeline System in 2004 and in the June 2004 Alaska Groundfish Fisheries Final Programmatic Supplemental Environmental Impact Statement prepared for the U.S. Department of Commerce, National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Alaska Region. The dissertation describes the process through which the cumulative effects assessment method presented here was developed and presents this approach as a predictive tool with the potential to improve the implementation of sustainable development in the United States. In this context, the dissertation presents an overview of sustainability theory, distinguishing and reviewing representative examples from two major sectors of the sustainable development literature, called here the intergenerational equity strand and the human development strand. It identifies weaknesses in three key areas of the intergenerational equity strand -- lack of theorectical cohesion, insufficient tools for implementation, and an imbalance between normative goals and practical feasibility -- and argues that the human development strand, with its empirical emphasis on metrics and institutional frameworks, offers a model that can serve as a basis for unifying the two strands by providing a theoretical core, implementation tools, and practicable goals. Finally, the dissertation argues that sustainable development is implemented most effectively when it is enabled by institutions that facilitate public involvement, particularly participation by the broadest feasible representation of the affected stakeholders, and that such institutional mobilization can provide a stable and enduring basis to foster the intergenerational equity that is the central, distinguishing feature of sustainability.Item Marine-continental transitions in a greenhouse world : reconstructing late Cretaceous deltas of paleopolar Arctic Alaska and Utah(2016-05) Van der Kolk, Dolores A.; Kerans, C. (Charles), 1954-; Hasiotis, Stephen T.; Steel, Ron; Snedden, John; Dalziel, IanNear horizontal (6° dipping) outcrop exposures of Upper Cretaceous (Santonian-Campanian) strata at Shivugak Bluffs in northern Alaska preserve an extensive record of a clinoform-topset system. These strata are generally subdivided lithostratigraphically into proximal shelf, deltaic, and shallow marine deposits of the Schrader Bluff Formation and lower delta plain, coastal plain, and fluvial deposits of the continental Prince Creek Formation. Shivugak Bluffs includes 400 m of continuous marine deposits overlain by 140 m of strata containing the marine–continental transition between the lower Schrader Bluff and Prince Creek formations. The marine-continental transition is one of the few outcrop expressions of an ancient, muddy, prograding river-dominated deltaic system that contains interdistributary bays that shoal upward into floodbasins with pedogenic modification. The lowermost 400 m of the lower Schrader Bluff Formation is divided into the Rogers Creek, Barrow Trail, and Sentinel Hill members interpreted as recurring deposits of river-dominated deltas comprising distributary mouth bars (DMBs), subaqueous terminal distributary channels (TDCs), interdistributary bays, medial delta front deposits, distal delta front deposits, and prodelta deposits interbedded with proximal shelf deposits. One interval within the Rogers Creek Member comprising the most hummocky cross-stratified (HCS) interval at Shivugak Bluffs is interpreted as wave-reworked DMB-TDC complexes or storm sheets. The Schrader Bluff (West Sak and Tabasco equivalent in the subsurface) and Prince Creek (Ugnu equivalent in the subsurface) formations are relevant to industry as outcrop analogs for numerous shallow, viscous- to heavy-oil reservoirs on the central North Slope, Alaska. From a reservoir perspective, a 36-m-thick subset of the Alaska succession within the Rogers Creek Member is compared to 36- and 34-m-thick wave-dominated successions of the Kenilworth and Grassy Members of the Blackhawk Formation in the Book Cliffs in eastern Utah. The Rogers Creek Member includes amalgamated DMB-TDC complexes (54%) with minor HCS wave-reworked deposits (46%). This succession is compared with the Kenilworth and Grassy members that exhibit predominantly swaley and HCS intervals (75–81%) with minor channel complexes (14–25%). The Blackhawk Formation, based on this analysis, is a poor reservoir analog for the lower Schrader Bluff Formation of Arctic Alaska.Item New geophysical parameters for understanding the evolution of the St. Elias Orogen, southern Alaska(2010-12) Worthington, Lindsay Lowe; Gulick, Sean P. S.; van Avendonk, Harm J; Pavlis, Terry L; Horton, Brian K; Cloos, Mark; Lavier, Luc LThe St. Elias Orogen is the result of oblique collision and flat-slab subduction in the Gulf of Alaska between North America (NA) and the Yakutat microplate (YAK). Extensive glaciation and a complex tectonic environment make this region a unique case study in which to examine the details of terrane accretion and the possible coupled influence of climate and tectonic drivers on the structural and topographic evolution of an orogenic wedge. The dataset for this project includes: 3 multi-channel seismic reflection surveys (~4000 km total seismic reflection data) and a ~450 km-long wide-angle seismic refraction profile. Reflection seismic profiles across the offshore YAK-NA deformation front, provide constraints for quantifying Pleistocene deformation recorded in the glaciomarine Yakataga formation. Growth strata and kinematic fold analysis allow comparison of relative timing of fault activity, which reveals temporal and spatial shifting of deformation within the margin towards the onshore eastern corner of the orogen. This information is important not only for the development of regional tectonic models, but also for understanding how climatic shifts may have affected the evolution of margin architecture during Pleistocene glacial-interglacial periods. Joint tomographic inversion of coincident reflection and refraction profiles constrains YAK crustal velocity and thickness. The offshore YAK crust ranges in thickness from 15 to 35 km, considerably thicker than normal oceanic crust. The crustal thickness and velocity structure support an oceanic plateau origin for the YAK microplate. Crustal velocity and structure are continuous across the YAK shelf except for a regional dip of the top of YAK crust of ~3° to the west. Moho arrivals across the profile do not mimic the dipping trajectory of the basement, indicating that the offshore YAK crust is doorstop-shaped, thinning in the convergence direction. This geometry leads to the following implications for the YAK-NA collision: first, uplift and deformation have intensified through time as successively thicker, more buoyant YAK crust attempts to subduct; second, current topography, exhumation and deformation patterns are partially controlled by underlying crustal geometry of converging YAK crust.Item Paleoreconstruction of Particulate Organic Carbon Inputs to the High-Arctic Colville River Delta, Beaufort Sea, Alaska(2013-01-09) Schreiner, Kathryn 1983-High Arctic permafrosted soils represent a massive sink in the global carbon cycle, accounting for twice as much carbon as what is currently stored as carbon dioxide in the atmosphere. However, with current warming trends this sink is in danger of thawing and potentially releasing large amounts of carbon as both carbon dioxide and methane into the atmosphere. It is difficult to make predictions about the future of this sink without knowing how it has reacted to past temperature and climate changes. This dissertation summarizes the results of the first study to look at long term, fine scale organic carbon delivery by the high-Arctic Colville River into Simpson?s Lagoon in the near-shore Beaufort Sea. Modern delivery of organic carbon to the Lagoon was determined to come from a variety of sources through the use of a three end-member mixing model and sediment biomarker concentrations. These sources include the Colville River in the western area of the Lagoon near the river mouth, marine sources in areas of the Lagoon without protective barrier islands, and coastal erosional sources and the Mackenzie River in the eastern area of the Lagoon. Downcore organic carbon delivery was measured on two cores in the Lagoon, one taken near the mouth of the Colville River (spans about 1800 years of history) and one taken on the eastern end of the Lagoon (spans about 600 years of history). Bulk organic parameters and biomarkers were measured in both cores and analyzed with Principle Component Analysis to determine long-term trends in organic carbon delivery. It was shown that at various times in the past, highly degraded organic carbon inputs of what is likely soil and peat carbon were delivered to the Lagoon. At other times, inputs of fresher, non-degraded, terrestrially-derived organic carbon inputs of what are likely higher amounts of plant and vegetative material was delivered to the Lagoon. Inputs of degraded soil carbon were also shown to correspond to higher temperatures on the North Slope of Alaska, likely indicating that warmer temperatures lead to a thawing of permafrost and in turn organic carbon mobilization to the coastal Beaufort Sea.Item Photo Identification, Summer Activity Pattern, Estimated Field Metabolic Rate and Territory Quality of Adult Male Sea Otters (Enhydra lutris) in Simpson Bay, Prince William Sound, Alaska(2010-07-14) Finerty, Shannon E.This project describes a portion of a long-term study of the behavioral ecology of sea otters. Sub-studies of this project include the development of an individual recognition program for sea otters, the construction of male sea otter activity and energy budgets, and the assessment of male sea otter territory quality. The Sea Otter Nose Matching Program, or "SONMaP", was developed to identify individual sea otters in Simpson Bay, Prince William Sound, Alaska, using a blotch-pattern recognition algorithm based on the shape and location of nose scars. The performance of the SONMaP program was tested using images of otters collected during the 2002-03 field seasons, and previously matched by visually comparing every image in a catalog of 1,638 animals. In 48.9% of the visually matched images, the program accurately selected the correct image in the first 10% of the catalog. Individual follows and instantaneous sampling were used during the summers of 2004-06, to observe male sea otter behavior. Six behaviors (foraging, grooming, interacting with other otters, patrolling, resting, and surface swimming) were observed during four time periods (dawn, day, dusk, night) to create 24-hr activity budgets. Male sea otters spent 27% of their time resting, 26% swimming, 19% grooming, 14% foraging, 9% patrolling and 5% interacting with other otters. Field Metabolic Rate (FMR) was estimated by combining the energetic costs for foraging, grooming, resting, and swimming behaviors of captive otters from Yeates et al. (2007) with these activity budgets. "Swimming" accounted for the greatest percentage (43%) of energy expended each day followed by grooming (23%), resting (15%), feeding (13%) and other (5%). With a peak summer sea otter density of 5.6 otters km-2, the low percentage of time spent foraging indicates that Simpson Bay is below equilibrium density. Territory quality was assessed for male sea otters using four attributes: territory size, shoreline enclosure, accessibility, and number of females observed feeding in each territory. Each attribute was coded with a score of 0-2, and total quality scores ranged from 0.14-1.96 (0.9 + 0.61 SD). High quality territories had large areas, moderate shoreline enclosure, high accessibility, and many foraging females.Item Seasonal dynamics of organic matter and inorganic nitrogen in surface waters of Alaskan Arctic streams and rivers(2015-12) Khosh, Matthew Solomon; McClelland, James W.; Dunton, Kenneth H; Liu, Zhanfei; Shank, Gerald C; Townsend-Small, AmyClimate-linked changes in hydrology and biogeochemical processes within Arctic watersheds are likely already affecting fluvial export of waterborne materials, including organic matter (OM) and dissolved inorganic nitrogen (DIN). Our understanding of Arctic watershed OM and DIN export response to climate change is hampered by a lack of contemporary baselines, as well as a dearth of seasonally comprehensive studies. This work focuses on characterizing OM and DIN concentrations and sources in six streams/rivers on the North Slope of Alaska during the entirety of the hydrologic year (May through October) in 2009 and 2010. The highest OM concentrations occurred during spring snowmelt, with results indicating that terrestrial vegetation leachates are the major source of dissolved OM, while particulate OM originates from a degraded soil source. Over the hydrologic year, soils became a progressively increasing source of dissolved OM, while autochthonous production made up a sizeable proportion of particulate OM during base flow conditions. DIN concentrations were low throughout the spring and summer and increased markedly during the late summer and fall. Our findings suggest that penetration of water into thawed mineral soils, and a reduction in nitrogen assimilation relative to remineralization, may increase DIN export from Arctic watersheds during the late summer and fall. Although recent studies of Arctic rivers have emphasized the importance of the spring thaw period on OM export, our understanding of the mechanisms that control water chemistry observations during this time are still lacking. Experimental leaching results, from experiments conducted in 2014, suggest that aboveground plant biomass is a major source of dissolved OM in Arctic catchments during the spring, and that the timing of freezing and drying conditions during the fall may impact dissolved OM leaching dynamics on that same material the following snowmelt. Improved knowledge of OM and DIN temporal trends and the mechanisms that control seasonal concentrations is essential for understanding export dynamics of these water constituents in Arctic river systems. Perhaps more importantly, increased understanding of the seasonal controls on OM and DIN export in Arctic rivers is critical for predicting how these systems will respond under future climate change scenarios.Item Seismic and morphologic analysis of the Gulf of Alaska Yakutat margin : evidence for recent trough mouth fan growth(2014-08) Swartz, John Marshall; Gulick, Sean P. S.; Goff, John; Catania, GinnyThe active St. Elias Orogen in southern Alaska was created by collision of the offshore Yakutat Terrane with North America. These mountains exhibit the highest coastal relief in the world and also are home to temperate tidewater glaciers, one of the most powerful erosive agents known. Glaciation in Southern Alaska has occurred since the Miocene, but climatic shifts associated with the intensification of Northern Hemisphere glaciation at ~2.5 Ma and the mid-Pleistocene transition at ~1 Ma have led to drastic increases in glacial erosion and associated offshore sediment transport and deposition. The Yakutat continental shelf has hosted ice streams during glacial advances since the mid-Pleistocene, but it is only recently that ice has reached the continental shelf edge itself. Quantitative morphologic analysis finds significant variability along the slope, with an relatively gentle gradient trough mouth fan building off the Yakutat Sea Valley, a shelf-crossing glacial trough, due to massive sediment supply from the heart of the St. Elias Orogen, while farther to the east the extremely steep continental margin is heavily gullied and sediment bypasses the slope reaching the offshore Surveyor fan. Seismic stratigraphy indicates that ice streams first reached the shelf edge with the mid-Pleistocene climate transition, a shift from 41 ka to 100 ka glacial-interglacial climate cycles. This increase in glacial durations allowed not only the ice to sustain advances to the shelf edge, but led to amplified erosion and climate-tectonic feedback effects.Item The Wicked Problem of Oil & Gas Development in the Beaufort and Chukchi Seas: Current Permitting and Evaluation of Marine Spatial Planning as a Potential Management Tool(2014-06-02) Johannes, Emilie AnnChanging climatic conditions and shifting global economics have thrust the Arctic into the spotlight for many scientists, academics, and policymakers as well as those in offshore industries, particularly in shipping and oil and gas. This research provides an overview of current U.S. Federal and State of Alaska environmental permitting requirements for offshore oil and gas development in the Beaufort and Chukchi Seas, highlighting the wicked problem of Arctic development: activities undertaken in the region are highly complex, involving significant political, social, environmental, and technical challenges. The economic opportunities that these Seas afford, and the high risks posed by pursuing these opportunities, call for the development of effective management strategies to avoid environmental catastrophes and maintain safe conditions for the stakeholders involved. The general questions guiding this research are: 1) How do Federal and State management of Beaufort and Chukchi Sea offshore oil and gas resources differ and how do the environmental permitting processes reflect this difference? 2) Is marine spatial planning (MSP) a viable tool for integrating these regulatory processes into a comprehensive planning process that balances stakeholder engagement, economic interests, and protection of the marine environment, all elements of the wicked problem? The analysis shows that MSP is worthy of consideration at the local or State level as a tool to help address these wicked problems elements, potentially allowing for a smoother permitting process.