• UAF's light-duty vehicle fleet lifecyle, maintenance costs and composition: ordinary least square regression and panel data analysis

      Hix, Edward R.; Wright, Christopher; Baek, Jungho; Little, Joe; Goering, Greg; Platt, Nathan (2020-08)
      The University of Alaska Fairbanks maintains a vehicle fleet for use by its staff, faculty, and students. Given the multifaceted needs of the campus and the impact that the harsh subarctic climate can have on vehicles, management of the fleet to meet the needs of its users is a complex task. One method UAF uses to manage the cost of the fleet is to extract the depreciation expense from each fleet vehicle into a non-interest bearing recharge account to eventually purchase its replacement. While several reviews have been conducted regarding the management of this fleet, a gap in research involves analysis of cost of this fleet over its lifecycle. This study examined the effects of fleet vehicle lifecycle extension beyond the predetermined 10-year useful life at UAF. Three novel datasets were created from UAF Facilities Services' archival maintenance work order data: a vehicle dataset, work order dataset, and a panel dataset. Ordinary least squares regression methods were used to examine the impact of model year on a vehicle's nominal purchase price and the impact of vehicle specification on real purchase price. Fixed and random effects panel methods were used to examine the impact of vehicle specification and vehicle age on maintenance costs. The effects of extending the fleet lifecycle from ten to twenty-years on maintenance and operational cost were estimated. Population dynamics models estimated the impact of the ten year lifecycle extension on the replacement fund. The results of this study suggested increasing vehicle lifecycles by ten years increased operating, maintenance, and replacement costs and effectively reduced the replacement fund purchasing power. The extension of vehicle lifecycles resulted in continually increasing rental rates and ultimately to the insolvency of the replacement fund.
    • Uncertainty quantification in unconventional reservoirs using conventional bootstrap and modified bootstrap methodology

      Okoli, Chukwuemeka; Awoleke, Obadare; Goddard, Scott; Ahmadi, Mohabbat (2020-12)
      Various uncertainty quantication methodologies are presented using a combination of several deterministic decline curve analysis models and two bootstrapping algorithms. The bootstrapping algorithms are the conventional bootstrapping method (CBM) and the modied bootstrapping method (MBM). The combined deterministic-stochastic combination models are applied to 126 sample wells from the Permian basin. Results are presented for 12 to 72 months of production hindcast given an average well production history of 120 months. Previous researchers used the Arps model and both conventional and modied bootstrapping with block re-sampling techniques to reliably quantify uncertainty in production forecasts. In this work, we applied both stochastic techniques to other decline curve analysis models∎namely, the Duong and the Stretched Exponential Production Decline (SEPD) models. The algorithms were applied to sample wells spread across the three main sub-basins of the Permian. A description of how both the deterministic and stochastic methods can be combined is provided. Also, pseudo-codes that describes the methodologies applied in this work is provided to permit readers to replicate results if necessary. Based on the average forecast error plot in the Permian Basin for 126 active wells, we can also conclude that the MBM-Arps, CBM-Arps, and MBM-SEPD combinations produce P50 forecasts that match cumulative production best regardless of the sub-basin and amount of production hindcast used. Regardless of concerns about the coverage rate, the CBM-Arps, MBM-Arps, CBM-SEPD, and MBMSEPD algorithm combinations produce cumulative P50 predictions within 20% of the true cumulative production value using only a 24-month hindcast. With a 12 month-hindcast, the MBM-Arps combined model produced cumulative P50 predictions with a forecast error of approximately 20%. Also, the CBM-SEPD and MBM-SEPD models were within 30% of the true cumulative production using a 12- month hindcast. Another important result is that all the deterministic-stochastic method combinations studied under-predicted the true cumulative production to varying degrees. However, the CBM-Duong combination was found to severely under-predict cumulative production, especially for the 12-month hindcast. It is not a suitable model combination based on forecast error, especially when hindcast fractions on the low end of the spectrum are used. Accordingly, the CBM- Duong combination is not recommended, especially if production history of no more than 24 months is available for hindcasting. As expected, the coverage rate increased, and the forecast error decreased for all the algorithm combinations with increasing hindcast duration. The novelty of this work lies in its extension of the bootstrapping technique to other decline curve analysis models. The software developed can also be used to analyze many wells quickly on a standard engineering computer. This research is also important because realistic estimates of reserves can be estimated in plays like the Permian basin when uncertainty is correctly quantied.
    • Understanding permafrost dynamics and geohazards with a terrain-cryofacies approach

      Stephani, Eva; Shur, Yuri; Doré, Guy; Darrow, Margaret; Kanevskiy, Mikhail (2021-12)
      The Arctic and its permafrost terrain are inherently dynamic, complex, and sensitive environments. Understanding the past and current changes occurring in these systems is key in predicting future variations, including the response of permafrost to climate change, and to terrain modifications resulting from natural processes or anthropogenic activities. This study contributes to advance our understanding of permafrost dynamics in varying permafrost environments of northern Alaska and northwestern Canada using a terrain-cryofacies approach. This unique approach helps to increase our understanding of permafrost dynamics from the site-specific scale to over extended areas by recognizing linkages between terrain and subsurface properties, and by identifying similar terrain units in remote sensing analysis. In the Colville River Delta (Alaska), our terrain-cryofacies study integrated data from 79 boreholes with a remote sensing analysis to evaluate the temporal changes in the Nigliq channel positions from 1948 to 2013 and the related permafrost dynamics. Most land cover changes occurred as land exposition (64%), whereas about 36% of the total changes were classified as eroded. The erosion of the older terrain units from the floodplain toposequence, such as the inactive-floodplain cover deposits, implied ground loss volumes of about one-fifth of soil solids and four-fifths of ground ice. Along this channel, we also identified the typical configuration and properties of taliks and cryopegs, as well as subsequent epigenetic permafrost growth. We found that the active channel was underlain by closed taliks, rather than through taliks and thus did not penetrate the entire layer of permafrost connecting supra- and sub-permafrost groundwater. A cryopeg connected to the active channel talik was identified from borehole data in the adjacent terrain units that developed following channel migration. We estimated the likelihood of encountering such taliks and cryopegs over extended areas. The terrain-cryofacies approach was also applied to understand permafrost dynamics of hillslope thermokarst located in multiple ecoregions of northern Alaska and northwestern Canada, including areas affected by interactions with infrastructure. Six features were studied through the combination of field-based and remote sensing methods, whereas 150 others were assessed solely by remote sensing. Studies along a pipeline indicated that embankment construction led to an increase in the active layer thickness, reaching the underlying ice-rich intermediate layer, and causing thaw settlement. This formed a thermokarst-ditch that facilitated channelization of cross-drainage water, and thermal erosion of the ice-rich permafrost that became affected by thermal denudation and caused a retrogressive thaw slump (RTS). The RTS later selfstabilized mainly due to the lateral discontinuity of massive ice (i.e., ice wedge) and the low-relief terrain. We suggested approaches to develop adaptation strategies for infrastructure at risk of RTS based on: these findings and conditions that favor or limit RTS growth by local feedbacks; considering the interaction patterns that we identified between RTS and infrastructure; and the main destabilization processes that we highlighted by terrain units. Further research is necessary, however, and must include testing potential mitigation techniques at multiple sites with monitoring programs to assess the variability in performance with respect to site-specific conditions.
    • Understanding the outcomes focused management production process: meta-analysis of the relationship between activities, settings, and the benefits of recreation participation

      Diamond, Kimberly; Fix, Peter J.; Peterson, Jen; Coker, Robert (2021-08)
      The 1958 Outdoor Recreation Resources Review Commission, through a 1962 report, tasked federal agencies to inventory supply and demand for outdoor recreation participation. Recreation managers are progressively focusing on demand for the beneficial outcomes of recreation, but have struggled to structure planning and management models to guide decisions that optimize recreationists' ability to attain desired benefits. The Outcomes Focused Management (OFM) framework links benefits to specific activity and setting combinations, giving managers a functional role in the process of benefit production. Past studies examining the OFM's activity-setting-benefit relationship reported weak results, but suggest activity is a stronger predictor of benefit attainment than setting. A better understanding of how activity and setting inputs affect recreationists' ability to realize desired benefits is needed for continued implementation of OFM, with the aim of improving attainment rates of positive recreation outcomes. This study used meta-analytic techniques with data compiled from 16 OFM studies to replicate and expand on published work. With the goal of improving the activity-setting-benefit model, this study introduced two predictor variables, previous visitation and visitors' residential proximity to the site, controlled for the desirability of the benefit, and re-conceptualized the setting variable by testing whether study site is a better predictor of benefit attainment than different settings within a site. Two-way analysis of variance tests measured the dependence of 40 personal (PER) and household, community, economic, environmental benefits (HCEE) on activity participation and setting, using effect sizes and significance levels to compare seven models. This meta-analysis reciprocated findings of a 2004 study, failing to offer definitive evidence of linkages among recreation opportunities in the context of the models tested. Benefit items exhibiting relatively higher sensitivity to activity and setting inputs were 1) "Restore my body from fatigue" (PER), 2) "Improved respect for privately owned lands" (HCEE), 3) "Increased self-confidence" (PER), and 4) "Greater respect for private property and local lifestyles" (PER). Suggestions for future OFM studies and research on the activity-setting-benefit relationship are made, in addition to a summary of potential implications for OFM based on the findings of this study.
    • Using ultraconserved elements to estimate gene flow between Asian and North American avian taxa

      Spaulding, Fern R.; Winker, Kevin; Drown, Devin; Takebayashi, Naoki (2021-08)
      Alaska is a prime location to study avian speciation, divergence, and gene flow. The area of Beringia, the region extending from the Russian Far East across the Bering Sea though Alaska, has historically experienced periodic cycles of glaciation. These cyclic fluctuations in climate have had genetic consequences on the organisms that reside in this region. In this thesis, I examine the genetic relationships between Old World and New World lineages of Holarctic avian taxa. Specifically, I examine how intercontinental movements (i.e., gene flow) have shaped divergence, speciation, and phylogenetic relationships in several key lineages of Holarctic waterbirds. Using ultraconserved elements (UCEs) as a molecular marker, I implemented population genomic analyses to better understand divergence, speciation, and levels of gene flow among several Beringian waterbird lineages. In the first of the two studies, I examine mitogenomic and nuclear DNA in a small clade of ducks with historically uncertain relationships and species limits: the Eurasian common teal (Anas crecca crecca), the North American green-winged teal (Anas crecca carolinensis), both seasonal migrants, and the sedentary Aleutian green-winged teal (Anas crecca nimia). In addition to the three subspecies of green-winged teal, I included the South American yellow-billed teal (Anas flavirostris), a close relative of Anas crecca, to fully resolve this teal complex. Phylogenetic relationships using nuclear DNA showed the three subspecies of Holarctic greenwinged teal (Anas crecca spp.) to form a polytomous clade with A. flavirostris being sister to this clade. However, mitogenomic data show a different phylogeny, with A. c. carolinensis being sister to A. flavirostris, while A. c. crecca was sister to A. c. nimia. Evidence for divergence with gene flow was present in all three pairwise contrasts of our demographic analyses. Given prior work, gene flow was expected among the Holarctic taxa, but gene flow between North American A. c. carolinensis and South American A. flavirostris, albeit low, was not. Three geographically oriented modes of divergence are likely involved: heteropatric speciation between A. c. crecca and A. c. nimia, parapatric speciation between A. c. crecca and A. c. carolinensis, and (mostly) allopatric speciation between A. c. carolinensis and A. flavirostris. In the second study, I applied genomic methods to estimate gene flow and the magnitude of intercontinental movements occurring in vector species of avian influenza. Many seasonally migratory birds that are vectors of avian influenza (i.e., waterbirds) fly between Eurasia and North America every year, but accurate numbers of birds crossing between continents have yet to be adequately determined. Vector species' movements are difficult to quantify, but population genomics can provide baseline rates of these intercontinental movements. My study examined the following species: northern pintail (Anas acuta), mallard (Anas platyrhynchos), greater scaup (Aythya marila), common eider (Somateria mollissima), green-winged teal (Anas crecca crecca - A. c. carolinensis), long-tailed duck (Clangula hyemalis), Eurasian and American wigeons (Mareca penelope - M. americana), and common and Wilson's snipe (Gallinago gallinago - G. delicata). Many of these species are also important as subsistence food for Alaskans, increasing the risk of direct bird-to-human avian influenza exposure. In addition to providing a robust intercontinental framework of movements (i.e., gene flow) for these vector species in the natural virus transport system, I examine them in the context of the importance of each species in Alaskan diets to understand the relative risk of these taxa to human Eurasian-origin avian influenza exposure. The inferred rates of movement between these populations varies greatly among lineages. These taxon-based intercontinental movement rates and relative risk rankings should help in modeling, monitoring, and mitigating the impacts of intercontinental host and avian influenza movements.
    • Utility of trace element studies for improving our understanding of geochemical processes within the arctic ocean environment

      Bolt, Channing; Aguilar-Islas, Ana; Rember, Robert; Reynolds, Jennifer; Rivera-Duarte, Ignacio; Simmons, Harper (2021-05)
      The Arctic Ocean is a dynamic region undergoing rapid change. Sea ice and meteoric water are intrinsic components of the Arctic environment that play key roles in its ecosystem, including the distributions and cycling of trace elements throughout the pan-Arctic Ocean. Meteoric water (e.g., rivers and snow deposition) contributes to the input of trace elements to surface waters, while sea ice dynamics contribute to the transport of these constituents across Arctic basins. Trace element distributions can provide insights into Arctic processes. The focus of Chapter One is on particulate (>0.2 μm) trace elements in Arctic pack ice, associated snow, and underlying surface waters collected from September-October 2015 during the US GEOTRACES Western Arctic cruise (GN01). This late-season pack ice provides a snapshot of sea ice characteristics in regions near the North Pole, within the Makarov and Canada Basins, and can estimate the impact melting sea ice may have on particulate trace element inputs to Arctic waters. Chapter Two presents on the utility of dissolved barium (dBa), a bio-intermediate element of lithogenic origin, as a tracer of meteoric water throughout the Siberian Arctic Ocean. Samples for Chapter Two were collected during the 2018 Nansen and Amundsen Basin Observatory System. The distribution of dBa in this region may provide useful insights into important shelf processes, such as tracing shelf waters along continental slopes. In Chapter 3, additional spatiotemporal geochemical parameters (δ¹⁸O and salinity) are considered alongside dBa to model how Arctic water mass fractions (meteoric, sea ice melt, and Atlantic waters) changed between 2013, 2015, and 2018 within the Siberian Arctic Ocean. This dissertation contributes to the understanding of Arctic Ocean processes through the application of trace element studies and highlights the usefulness of combining tracers to better understand this dynamic environment.
    • Vertebrate ichnology and paleoenvironmental associations of Alaska's largest dinosaur track site in the cretaceous Cantwell Formation (Maastrichtian) of Denali National Park and Preserve

      Stewart, Dustin G.; Druckenmiller, Patrick; Fowell, Sarah; McCarthy, Paul (2020-10)
      The Upper Cretaceous Cantwell Formation in Denali National Park and Preserve (DENA) has recently been recognized as a major high latitude dinosaur track-bearing unit in Alaska. The abundant trace fossil record of the Cantwell Formation, which represents a diverse community of avian and non-avian dinosaurs, compliments the body fossil record of the state's other major dinosaur-producing unit, the Prince Creek Formation of northern Alaska. However, research in the Cantwell Formation is still in its infancy due to its wide aerial extent and remoteness, and many questions remain concerning the temporal, ichnological, and paleoenvironmental relationships of the formation. Here I describe and analyze the largest known single track site currently known in DENA and all of Alaska -- a football field-sized outcrop named the Coliseum. This site is composed of 65+ meters of vertical section, with laterally extensive fine- to medium-grained sandstone, indurated mudstone, fissile shale, and bentonite. Trace fossils at the Coliseum include true tracks, undertracks, natural casts, and trackways that vary in their preservation from eroded, trampled surfaces to individual prints with skin impressions. The tracks were documented via handheld and UAV-assisted photogrammetry, enabling a large-scale 3-dimensional mapping of the Coliseum. Facies analysis of the site reveal the tracks were formed on crevasse splay and overbank deposits within a fluvial floodplain. U-Pb dating of zircons collected from a bentonite horizon return an age of 69.3±0.9 Ma (early Maastrichtian), improving the temporal constraints of the formation and revealing one of the youngest ages of deposition for the formation. Several new dinosaurian ichnotaxa previously unrecognized from the formation are described, revealing the presence of large-bodied ornithopods, ceratopsids, and non-avian and avian theropod trackmakers. The Coliseum provides a snapshot of an ancient forested environment inhabited by a diverse dinosaurian community deposited in the Late Cretaceous paleo-Arctic.
    • Vetting model and satellite-based estimates of regional scale carbon exchange at northern high latitudes using solar-viewing infrared spectroscopy

      Jacobs, Nicole; Simpson, William R.; Euskirchen, Eugénie S.; Guerard, Jennifer; Maxwell, David A. (2021-08)
      Carbon exchange in the Boreal Forest and its response to a warming climate is a critical process that needs to be understood for more accurate predictions of climate change. Therefore, we established a ground-based long-term monitoring site at the University of Alaska Fairbanks in Fairbanks, Alaska, USA (64.859°N, 147.850°W) operating a solar-viewing Bruker EM27/SUN Fourier transform infrared spectrometer (FTS). This instrument measures vertically integrated column abundances of carbon dioxide (CO₂), methane (CH₄), and carbon monoxide (CO), termed Xgas, i.e., XCO₂. These measurements are directly comparable to satellite-based measurements, for which these ground-based observations provide validation data. Measurements of XCO₂ and XCH₄ have to be extremely precise because variability in atmospheric columns of CO₂ and CH₄ is often less than 1% of the background levels of these long-lived gases. Therefore, the observations in Fairbanks were carefully vetted through comparisons of results from two retrieval algorithms applied to the same observed spectra, comparisons of observations from two EM27/SUN FTS operating side-byside, and comparisons between an EM27/SUN FTS and measurements from a Bruker IFS125HR in the Total Carbon Column Observing Network (TCCON) at Caltech, Pasadena, California. These data are all collected over a period of about 4.5 years. Comparisons of retrieval methods indicate that the results are tightly correlated, but there are offsets that could be corrected with an appropriate scaling factor. Observed biases between two colocated EM27/SUN FTS were in agreement within instrument precision. Biases between the EM27/SUN and TCCON retrievals at Caltech are larger and more variable than biases between the two EM27/SUN FTS in Fairbanks, which may be partially explained by differences in spectral resolution. These biases are also similar to those reported in previous studies. Vetted Fairbanks observations are used in combination with those from two TCCON sites in the Boreal Forest, East Trout Lake, Saskatchewan, Canada (54.354°N, 104.987°W) and Sodankylä, Finland (67.367°N, 26.631°E), to evaluate quality control methods and bias in XCO₂ from the NASA Orbiting Carbon Observatory 2 (OCO-2). This study yielded alternative quality control thresholds and bias correction, tailored to Boreal Forest regions that allow for increased data throughput and reduced seasonality in bias over northern high latitude regions. In particular, increased data throughput in spring and autumn months made it possible to measure XCO₂ seasonal cycles using satellite-based measurements. In this analysis, we found that the Asian Boreal Forest region stood out as having the largest seasonal amplitude and earliest seasonal drawdown of any region. There is also a pronounced west-to-east gradient of increasing seasonal amplitude and earlier seasonal drawdown across the Eurasian continent. Comparisons with two independent global CO₂ models are good, showing high correlation and spatial agreement. Analysis of modeled (GEOS-Chem) surface contact tracer contributions reveals that the largest seasonal amplitudes occur in regions that have the largest contributions from land-based surface contact tracers with 15 or 30 day atmospheric lifetimes, suggesting that accumulations of CO₂ exchanges during atmospheric transport on approximately monthly timescales play an important role in shaping observed XCO₂ seasonal cycles in northern high latitude regions. Furthermore, surface contact tracer contributions from land were more correlated with XCO₂ seasonal amplitude than estimates of total annual fluxes or seasonal amplitudes of flux estimates within a region, emphasizing the importance of understanding the effects of atmospheric transport when interpreting observations of XCO₂.
    • Western Gwich'in classificatory verbs

      Bushey, Scott T.; Tuttle, Siri; Peter, Hishinlai'; Vajda, Edward (2021-05)
      One of the many challenges faced by learners and teachers of Gwich'in, an endangered Athabascan or Dene language of Alaska and Canada, is a lack of instructional material for classificatory verbs. These verbs classify states and actions, such as lie, carry, and fall, by perceived qualities, such as cloth-like and stick-like, that indicate how and with which nominal entities the state or action takes place. For students of Gwich'in and other Dene languages, such as Navajo and Koyukon, classificatory verbs are an important grammar objective when included in the curriculum. Recognition and production of classificatory verbs is a main objective for students in the second year of the UAF Gwich'in class. Classificatory verb words are also present in vocabulary learned from the first year, such as gishreiin'ąįį "it's sunny" and OBJ naltsuu "I'm wearing OBJ [upper-body garment]". In this thesis I present a documentary, descriptive study of classificatory verbs and their qualities in modern spoken Gwich'in. The first goal of the study is to document examples of Gwich'in classificatory verbs in conversational and narrative discourse, and the second is to describe their morphosemantic properties and behavior. The third goal is to accomplish these documentary and descriptive aims in a way that can be adapted readily to the needs of not only linguists, but also Gwich'in language learners and teachers. Informed by previous documentary and descriptive work on classificatory verbs in other Dene languages, I attempt to provide a similarly useful text for Gwich'in, reconciling several competing nomenclatures and illustrating the relationship between classificatory verb theme sets, such as "carry", and semantic classes of verb stems, such as "animate", in a broad range of modal and aspectual contexts. Although this thesis is intended primarily as a reference work for learners and teachers, it also provides a resource for linguists comparing Gwich'in classificatory verbs with those in related Dene languages. The classificatory verb data in this thesis is drawn from a body of Gwich'in class notes and assignments, well as transcribed Gwich'in oral literature and consultation with a native speaker of the language. Classroom instruction took place between 2018 and 2020 at the University of Alaska Fairbanks and emphasized spoken language production with communicative aims. In addition to work from the Gwich'in language classroom, limited native speaker consultation regarding classificatory verbs was also conducted in February 2020. The third data source for this study is the rich body of narrative discourse available in the form of transcribed oral literature. These works record Gwich'in traditional narrative knowledge, lore, and history across a broad range of topics, in which classificatory verbs may be readily encountered and examined. Having drawn from these three pools of data, this thesis describes the morphosemantic qualities of Gwich'in classificatory verbs while considering the available data on other Dene languages and considers actual and potential application of this data in the language classroom.
    • Widespread capacity for denitrification in soils, streams, and thermokarst lakes of boreal Alaska

      Burnett, Melanie S.; Harms, Tamara K.; Ruess, Roger W.; Walter Anthony, Katey M. (2021-05)
      Rapid warming in Alaska is causing permafrost to thaw, especially in the region of discontinuous permafrost, where soil temperatures may only be a few degrees below 0 °C. An intensifying fire regime may also be exacerbating permafrost thaw with more frequent and severe fires removing insulating organic layers above permafrost. Permafrost thaw releases carbon and nitrogen (N) into the actively cycling pools, and whereas carbon emissions following permafrost thaw are well documented, the fates of N remain unclear. Denitrification and release of nitrous oxide (N₂O) or nitrogen gas (N₂) could result in N loss from ecosystems, but the contributions of these processes to the high-latitude N cycle remain uncertain. I quantified microbial capacity for denitrification and nitrous oxide production in boreal soils, lakes, and streams, and assessed correlates of denitrifying enzyme activity in interior Alaska to determine if denitrification could contribute significantly to N loss from the boreal forest. Across all landscape positions, median potential denitrification rate under anoxic conditions with nitrate and organic carbon amendment was 4.15 [mu]g N₂O-N /kg dry soil*h (range -6.39 to 479.94). Denitrification potential was highest within and along streams in both sediments and adjacent riparian soils, upland soils were intermediate, and lakes supported lower rates, whereas deep permafrost soils supported little denitrification. Time since last burn had no effect on denitrification potential in upland soils. Across all landscape positions, denitrification potential was negatively correlated with ammonium pools. In lakes, potential rate of denitrification declined with sediment depth, and was positively driven by organic matter content. In this era of anthropogenic climate change, pervasive N loss to denitrification in the boreal forest could constrain the capacity for N-limited primary producers to preserve carbon stocks in soils following permafrost thaw.
    • Zooplankton community composition in relation to environment and juvenile salmon diets in Icy Strait, Southeast Alaska

      Fergusson, Emily A.; Eckert, Ginny; McPhee, Megan; Heintz, Ron (2020-12)
      Zooplankton in the nearshore marine habitat function as an important prey resource for many pelagic fishes, are a major component of the lower tropic level, and serve as a vital ecosystem indicator. Understanding how the zooplankton community changes in response to fluctuations in biophysical factors is critical in a changing climate and is important to understanding the dynamics of commercially important upper-trophic level species that depend nutritionally on zooplankton. The Alaska Fisheries Science Center's Southeast Coastal Monitoring project has surveyed the pelagic ecosystem in eastern Icy Strait monthly from May to August since 1997 to understand how environmental variation affects the pelagic food web and the sustainability of salmon resources. I used this long-term dataset (1997-2017) to address the goals of this study: 1) to investigate the influence of temperature on the Icy Strait zooplankton community; and 2) to understand how juvenile salmon utilize zooplankton prey in relation to temperature driven fluctuations in the zooplankton community. In Chapter 1, I noted that the composition of the zooplankton community varied in years with anomalously high or low temperatures. I observed shifts in the timing of development in many key taxa during these anomalous years. For example, in anomalously cool years, several taxa were found in higher densities later in the summer than in anomalously warm years. In Chapter 2, I examined how oceanographic factors influenced the diet composition and quality of four species of juvenile Pacific salmon (Oncorhynchus spp.) in Icy Strait (Southeast Alaska) from 2013 to 2017. In 2015 I observed a change in diets, including zooplanktivorous (pink salmon O. gorbuscha, chum salmon O. keta, and sockeye salmon O. nerka) and piscivorous (coho salmon O. kisutch) species, from typically diverse diets to diets dominated by euphausiids. This year was notable for warm waters, deep pycnoclines, and below average zooplankton nutritional quality. Juvenile salmon appeared to supplement their lipid intake and meet nutritional requirements by switching to larger euphausiid prey. The results from these studies increase our understanding of zooplankton community dynamics, salmon trophic relationships, and the resilience and flexibility of the food web during climate-driven reorganizations of the pelagic marine ecosystem.