• Landscape characteristics influence climate change effects on juvenile chinook and coho salmon rearing habitat in the Kenai River watershed

      Meyer, Benjamin; Rinella, Daniel; Wipfli, Mark; Schoen, Erik; Falke, Jeffrey (2020-08)
      Changes in temperature and precipitation as a result of ongoing climate warming in south-central Alaska are affecting juvenile salmon rearing habitat differently across watersheds. Work presented here simulates summer growth rates of juvenile Chinook and coho salmon in streams under future climate and feeding scenarios in the Kenai River (Alaska) watershed across a spectrum of landscape settings from lowland to glacially-influenced. I used field-derived data on water temperature, diet, and body size as inputs to bioenergetics models to simulate growth for the 2030-2039 and 2060-2069 time periods, comparing back to 2010-2019. My results suggest decreasing growth rates under most future scenarios; predicted changes were of lower magnitude in the cooler glacial watershed and main stem and more in montane and lowland watersheds. The results demonstrate how stream and landscape types differentially filter a climate signal to juvenile rearing salmon habitat and contribute to a broader portfolio of habitats in early life stages. Additionally, I examined two years of summer water temperature data from sites throughout our study tributaries to assess the degree to which lower-reach sites are representative of upstream thermal regimes. I found that the lower reaches in the lowland and glacial study watersheds were reasonably representative of daily and seasonal main stem thermal conditions upstream, while in the montane study watershed (elevation and gradient mid-way between the lowland watershed) upstream conditions were less consistent and thus less suitable for thermal characterization by a lower-reach site alone. Together, this work highlights examples of the importance of accounting for habitat diversity when assessing climate change impacts to salmon-bearing streams.
    • Life cycles of the kelps Saccharina latissima and Alaria marginata: implications for mariculture and ecology in Alaska

      Raymond, Annie E.T.; Stekoll, Michael S.; Eckert, Ginny L.; Bergstrom, Carolyn A. (2020-08)
      Kelp farming has the potential to economically diversify coastal communities of Alaska while offering other ecosystem services, including carbon sequestration and mitigation of eutrophication. Two bottlenecks to the expansion of the industry are understanding the natural kelp life cycle and manipulating the life cycle to produce seed. We address these questions with specific research aimed to increase knowledge of the expected natural variability of the kelp life cycle and test methods to effectively manipulate storage of kelp seed string to add flexibility to the kelp farming industry. First, in Chapter 1, we documented the patterns of sporophyte fertility for two commercially important kelp species, Saccharina latissima and Alaria marginata, in the wild. We found S. latissima exhibited both annual and perennial life history varying by location and year, with an increasing proportion of fertile sporophytes present in the fall and winter season. In contrast, A. marginata displayed a predictable annual life history, recruiting in spring with the proportion of fertile sporophytes increasing into the fall. Results from Chapter 1 suggest A. marginata has a more reliable brood stock availability and, therefore, has the potential to be a suitable commercial crop. Ecologically, Chapter 1 results suggest A. marginata may contribute consistently to habitat across Alaska in spring and summer months. In Chapter 2, we tested how different culture conditions, including light, temperature, and culture media, affected gametophyte growth with the goal of developing storage methods for kelp seed string. We found that low temperature is effective in slowing gametophyte growth and reducing gametogenesis and is the best condition for seed storage. Further experiments tested how storage in cold temperatures affects seed quality, leading to the development of a method called "cold banking," which enables extended seed storage or staggering of seed string for at least an additional thirty-six days in a storage setting without adverse effects to sporophyte density and length at the time of outplanting and up to three weeks after outplanting. Ecologically, Chapter 2 results demonstrate the diversification of microscopic stages used as an overwintering strategy by S. latissima. As the kelp mariculture industry is expected to grow in Alaska and around the world, we hope this information will be a jumping-off point for research promoting productive and sustainable commercial kelp production.
    • Long-term shifts in community structure, growth, and relative abundance of nearshore Arctic fishes: a response to changing environmental conditions

      Priest, Justin T.; Sutton, Trent M.; Mueter, Franz J.; Raborn, Scott W. (2020-08)
      Environmental conditions influence the presence, species composition, abundance, and growth of fish species in the nearshore Arctic ecosystem. With ongoing shifts in Arctic conditions due to climate change, how fish communities and individual species respond to such changes to environmental variability more broadly is unknown. This study analyzed catch and length data from a long-term fish monitoring project near Prudhoe Bay, Alaska, 2001-2018, to quantify the effects of environmental variables on the overall fish community and on the juveniles of two important whitefishes, Arctic Cisco Coregonus autumnalis and Broad Whitefish Coregonus nasus. Abundance data (n = 1.78 million fish) from daily sampling (July-August) at four stationary sampling locations showed distinct shifts in fish community metrics. Since 2001, annual species richness has significantly increased by one species per decade while water temperature warmed by over 1.4°C. The species composition based on biweekly catch data has significantly changed across years, with distinct variations among sample locations and throughout the season. Species composition was significantly affected by both salinity and water temperature. The effects of environmental conditions on growth showed that water temperature was positively and linearly associated with increases in growth for juvenile whitefish, while salinity negatively affected growth of age-0 Arctic Cisco. Changes in the abundance of juvenile whitefishes were related to both water temperature and salinity. Results from all analyses suggest that species positively associated with observed warming in the aquatic environment are generalist species such as Broad Whitefish. This study concluded that continued climate change, and especially Arctic warming, will likely increase growth, change the species composition, and alter abundance in the Arctic nearshore ecosystem. These changes will have impacts on subsistence harvests and on upper trophic level species that prey on nearshore fishes.
    • Mental health problems in the mountains: needs, assets, and recommendations for managing mental health problems in mountain-focused wilderness-based education and related fields

      Johnson, Samuel H.; Dulin, Patrick L.; Lopez, Ellen D. S.; Gifford, Valerie M.; Rivkin, Inna D. (2020-08)
      Background: Through controlled exposure to stress, wilderness-based education programs can buildcapacity for adaptive coping and produce long lasting improvements to participants' quality of life.However, stress can also overwhelm them, resulting in the emergence and exacerbation of mental health vulnerabilities in the field. However, empirically grounded best practices for training, pre-trip screening, and protocol/policy for mental health specific to the wilderness context are not well developed. Aim: The aim of this study was to assess needs and assets, and develop recommendations for training, pre-trip screening, and organizational protocol/policy to assist with successful management of mental health problems in mountain-focused, wilderness-based education and related fields such as outdoor leadership, guiding, environmental education, snow safety, search and rescue, and wilderness therapy. Methods:A pragmatic, two phase, sequential mixed methods approach was utilized to explore this topic within the context of an overarching collaborative community based participatory research (CBPR) framework with organizational partners: National Outdoor Leadership School, Outward Bound USA and Canada, the Wilderness Risk Management Conference, and the Alaska Mountaineering School. A preliminary quantitative study utilized a cloud-based survey to determine baseline characteristics for 64 wilderness-based educators, guides, outdoor leaders, snow safety professionals, and search and rescue personnel. Qualitative interviews with 16 experienced and prepared key informants addressed the study aim in more depth, consistent with partnering organization priorities, in the tradition of CBPR. Findings: Mental health topics and skills are underemphasized in current training, and training was found to be of less value than personal and professional experiences with mental health. In the future, mental health should be increased and emphasized, possibly through the utilization of existing resources such as the stress continuum or curriculum such as Psychological First Aid as well as practical training opportunities that emphasize experiential learning around mental health. Current screening can present both risks and benefits for clients, instructors, and organizations. Nondisclosure and the impacts of stigma and prejudice on the interpretation and utilization of mental health screening information were major concerns. However, screening can guide preventive and proactive efforts, and build working relationships with potential participants. Future screening should be used to inform participants about course stress, encourage disclosure, and direct curriculum development. Multi-step screening, utilizing multiple interactions with participants before the course, was identified as a utilitarian way to facilitate improvements for future screening. In protocol/policy, field management of mental health problems is underemphasized relative to evacuation, resulting in overutilization of disruptive evacuation processes. While many organizations do well at responding to instructor mental health needs after incidents such as a fatality in the line of work, inconsistencies in implementation can create unintended barriers to instructor self-care. Future protocol/policy should prioritize instructor mental health by addressing inconsistencies in implementation, removing barriers to self-care and guiding the deployment of resources such as responsive staffing or free counseling benefits. Implications: This study contributes uniquely to the literature by providing an empirically-based perspective into a little researched topic, and multiple avenues for implementation of findings such as increasing mental health content and experience-based training, utilization of multi-step screening processes, and consistent implementation of organizational protocol/policy in support of client and instructor mental health. Recommendations for implementation address weaknesses and build upon strengths already present in training, screening, and protocol/policy. Overall, practice and research in this area are in need of further investigation and development. Future dissemination, research, and practice development could help develop measures or resources to support the improvement of training, screening, and protocol/policy across wilderness-based education and related fields.
    • Metabolite influence on the hibernating Arctic ground squirrel

      Rice, Sarah A.; Drew, Kelly; Kuhn, Thomas; Coker, Robert; Ritter, Robert (2020-12)
      Hibernation is a state of extreme metabolic plasticity and fasting. How hibernators maintain nitrogen homeostasis and regulate amino acid metabolism and how those metabolites influence hibernation physiology remains unknown. We first utilized three approaches to understand nitrogen homeostasis and amino acid metabolism in hibernation: longitudinal metabolic profiling within individual animals over undisturbed torpor, in vivo amino acid isotope tracing in deep torpor, and ¹⁵N isotope tracing in vivo during arousal from hibernation in Arctic Ground Squirrels (AGS). We observed that in vivo whole body production (WBP) of metabolites in deep torpor are profoundly and selectively suppressed in deep torpor. Metabolic profiling over undisturbed torpor bouts shows amino acids with nitrogenous side chains accumulate over torpor while urea cycle intermediates remain unchanged. During arousal from hibernation, ¹⁵N isotope tracing demonstrates recycling of free nitrogen into non-essential amino acids, essential amino acids and the gamma-glutamyl system. We next utilized two approaches to understand potential metabolite influences on thermogenesis and behavior in hibernation: we infused ammonium acetate in deep torpor and fed diets high in omega 3 fatty acids and monitored body temperature and torpor bout length. We found high doses of a nitrogen donor, ammonium acetate, as well as diets high in omega 3 fatty acids both influence thermogenesis in hibernation. In conclusion, production of metabolites in deep torpor indicate highly regulated metabolism with accumulation of nitrogen carrying amino acids. We additionally show metabolites and nitrogen can exert thermogenic influence on hibernating AGS.
    • Meteorological drivers of lightning in Alaska on seasonal and sub-seasonal timescales

      Chriest, Jonathan; Bhatt, Uma S.; Bieniek, Peter A.; Walsh, John E. (2021-05)
      Wildfire has long been a part of the Boreal forest ecosystem in Alaska and the increasing number of large fire seasons over the past 2 decades has had substantial economic and health impacts. Boreal wildfires are expected to continue to increase over the next century in part due to a projected increase in lightning. This motivates developing lightning outlooks to inform fire management decisions regarding the economic allocation of shared firefighting resources including but not limited to personnel and air tankers. The goal of this research is to identify key meteorological parameters associated with lightning processes on a stroke-by-stroke spatial scale and at hourly-to-sub-seasonal timescales. This is a first step towards developing robust lightning outlooks. In order to identify the key parameters, lightning data for the Alaska Lightning Detection Network was paired with hourly European Center Reanalysis Version 5 (ERA5) over the 2012-2019 study period. This data was analyzed on the scale of Alaska Fire Service Predictive Service Areas (PSAs) and three sub-seasons of the Alaska fire season. This strategy helped to identify regional and sub-seasonal variability and made the research operationally relevant. Key results from this research include the following. The majority of lightning occurs in the duff driven sub-season across all PSAs. Lightning, particularly in the Interior PSAs, follows a diurnal pattern with lightning on average beginning earlier in the day in the eastern portion of Alaska and later in the day in the western portion of Alaska. This distinctive pattern is not as well defined in the Coastal PSAs. Results also suggested that dry lightning may be more prevalent in portions of the western Interior than in other regions of Alaska. Lightning events were more common under specific atmospheric flow directions at 500 and 700 hPa, where these directions varied by PSA. Northeasterly and northwesterly flow aloft were most favorable for lightning in the Tanana Valley West PSA, while southerly flow aloft was more favorable for lightning in the North Slope and Upper Yukon PSAs. Finally, easterly flow was a more common pattern during lightning strokes in the Seward Peninsula and Kuskokwim Valley PSAs.
    • Modeling permafrost dynamics and water balance of Arctic watersheds in a changing climate

      Debolskiy, Matvey Vladimirovich; Hock, Regine; Romanovsky, Vladimir E.; Alexeev, Vladimir A.; Nicolsky, Dmitry J. (2020-12)
      Changes in climate across the Arctic in recent decades and especially the increase of near-surface air temperature promote signicant changes in key natural components of the Arctic including permafrost (defined as soil experiencing subzero temperature for more than two consecutive years). Recent borehole observations exhibit signicant increase in ground temperatures below the depths of seasonal variations. Modeling studies on a global scale suggest a steady decrease in area underlain by near-surface permafrost in the northern hemisphere in recent decades. Global projections for the next century predict further permafrost degradation depending on the greenhouse gas concentration trajectory. Permafrost degradation is not only associated with climate feedbacks but can also result in signicant changes in coastal and terrestrial ecosystems and increased risks of costly infrastructural damage for Arctic settlements. In addition, permafrost plays an important role in the terrestrial part of the Arctic freshwater cycle as the volumes of frozen ground are practically impermeable for subsurface moisture transport and contain excess water in the form of ground ice. Since geophysical observations bear signicant costs in the Arctic, especially in the remote areas, simulations performed with physically based numerical models allow researchers to assess the current state of permafrost in Arctic regions and make future projections of its dynamics and resulting hydrological impacts. In this dissertation we use numerical modeling in two distinct ways: 1) to estimate current and future ground temperature distribution with high resolution on a regional scale and 2) to evaluate the role permafrost degradation plays in changes in water balance of watersheds under changing climate. First, we study the permafrost evolution of the Seward Peninsula, Alaska over the 20th and 21st century using a distributed heat transfer model. Model parameters are calibrated with a variational data assimilation and are distributed across the study domain with an ecosystem type approach. Simulations suggest that the peninsula will experience a reduction in the near surface permafrost extent of up to 90% and an average increase in ground temperature across the peninsula up to 4.4°C towards the end of the 21st century under the high greenhouse gas concentration trajectory. Second, we perform an ensemble of millennia-long experiments by simulating hypothetical idealized small-scale watersheds placed in a typical Sub-Arctic setting with a physically based distributed hydrological model. In these experiments we single out the effects of temperature dependent subsurface moisture transport by applying air temperature change in our forcing scenarios only to sub-zero temperatures within a given year. Results suggest a long-term increase in annual runoff of 7-15% and a similar decrease in evapotranspiration under a prolonged (up to a millennia) air-temperature increase. The short-term (< 100 years) water balance response highly depends on soil permeability and the watersheds slope and profile curvature. The simulated changes in water balance are a direct result of the decrease in near- surface soil moisture and intensified subsurface moisture transport in the deeper soil layers due to the permafrost thaw. Additional experiments suggest that simplied models that do not include lateral subsurface moisture transport, as typically done in Earth System Models, can reproduce similar changes in equilibrium water balance to the ones predicted by more sophisticated models for the watersheds with gentle slopes. We also find that if the air temperature trend is reversed and watersheds are experiencing prolonged cooling, a high degree of hysteresis in water balance behavior can be observed, however, the long-term changes in water balance are equal in their amplitude. Additionally, we find that initial soil moisture distribution in the deeper soil which is essentially a consequence of the paleoclimate (given the same permeability and topography) determines the overall soil moisture storage deciency which in turn results in the lag between the onset of warming and the increase in total runoff. The deficit in soil moisture storage is highly dependent on the watersheds topography.
    • Paleocene depositional history of the Cretaceous-Paleogene impact basin, Yucatan Peninsula, Mexico

      O'Malley, Katherine E.; Whalen, Michael; Fowell, Sarah; McCarthy, Paul (2020-12)
      In the spring of 2016, the International Ocean Discovery Program set out on Expedition 364 to recover core from the peak ring of Chicxulub Impact Crater at Site M0077. In total, 829 m of core was collected spanning granite to Paleogene sedimentary rocks. From this core, we have a well-preserved record of the Paleocene, which represents ~10 million years post impact in just under 10 m of sedimentary rock record. This has presented an incredible research opportunity, as we have gained invaluable information on how the environment responded and recovered from the global catastrophe that was the Chicxulub Impact. The Paleocene at M0077 is highly condensed and comprised of predominantly pelagic carbonate rocks. High resolution core logging and thin section analysis were used to identify facies in the Paleocene. Facies include marlstone, argillaceous wackestone, foraminiferal wackestone, and rare coarser grained lithologies such as packstone and grainstone. Overall, the Paleocene exhibits a succession of rhythmically bedded cycles composed of marlstones grading to argillaceous wackestones and capped by foraminiferal wackestones. Coarser grained lithologies only exist in the lower and uppermost portion of the core. In total, 72 cycles that ranged from 5-30 cm thick are identified and grouped into six larger packages based on pattern similarities in color, lithology, ichnofabric indices, and geochemical data. These cycles are interpreted as parasequences, and show predictable stacking patterns that allow us to make sequence stratigraphic analyses. Each package represents one to two systems tracts, and some can be correlated to eustatic sea level change. Recorded in this core is the progression of an initial sea level lowstand immediately post impact, and the fluctuation between highstands, lowstands, and transgressive systems tracts that follow. Major and trace elements were analyzed throughout the core, as well as delta¹³Corg and delta¹⁵Nbulk values. Three sets of geochemical proxies (paleoredox, detrital input, productivity) were used to provide insight into paleoecological conditions. Initial conditions in the crater show a period of high productivity, which tapers off within a million years post impact. Redox conditions vary, and show one major anoxic event, with other enrichments likely representing periods of pore water euxinia or increases in stratification leading to a more robust redox gradient.
    • Photosensitized degradation of chlorothalonil and chlorpyrifos in the presence of Arctic derived dissolved organic matter

      Quesada, Ginna; Guerard, Jennifer; Rasley, Brian; Green, Thomas (2021-05)
      Pesticides used at mid latitudes can accumulate in Arctic environments. Two commonly detected pesticides in Arctic lakes are chlorothalonil and chlorpyrifos. In surface waters, photolysis can play an important role in the attenuation of contaminants. The chemical characteristics of dissolved organic matter (DOM) can further alter the extent of photolytic degradation of pollutants. To determine the relative effect of natural Arctic lake water and its DOM on the photolysis of chlorpyrifos, experiments were conducted under natural Arctic irradiation and under artificial irradiation. Similarly, the effect of Arctic DOM was investigated for chlorothalonil under artificial irradiation. The fulvic acid (FA) fraction of DOM was isolated from Fog 1 and from Toolik Lake in May and July. Lake waters significantly enhanced the photodegradation of chlorpyrifos under natural light by up to an order of magnitude. FA's significantly increased the degradation of chlorpyrifos (>2x) and chlorothalonil (>100x) under artificial irradiation relative to 18 MΩ-cm Water. Toolik Lake FA isolated in May, significantly enhanced the photolysis of both contaminants relative to the isolate collected in July. In the presence of iron, a lower ratio of carbohydrates and peptides to aromatics in the FA's was associated with faster degradation for chlorothalonil.
    • Reevaluating recent temporal trends in animal body size: the role of demography

      Theriot, Miranda K.; Olson, Link; Doak, Patricia; Millien, Virginie (2021-05)
      Climate change over recent decades is associated with varied responses in animals, including both increases and decreases in body size. These opposing trends are often attributed to two primary hypotheses. In warm-blooded vertebrates, Bergmann's rule predicts decreases in average size with increasing temperature, based on the relationship between body size and thermoregulation. Alternatively, increased average body size is linked with changes in resource availability as summer growing seasons lengthen and winters becomes milder. We propose a third explanation, that shifts in demography underlie some of these observed trends, as many species change in size or shape throughout life. The influence of thermoregulatory demands, resources, and demography on body size trends are not mutually exclusive; disentangling these effects and identifying overarching patterns requires detailed analyses across multiple locations and taxa, which in turn necessitates repeatable and expandable studies. To that end, here we propose three best practices in body size research: defining and justifying measures of size, citing museum specimens, and accounting for demography. We employed these guidelines in a study on masked shrews (Sorex cinereus) in Alaska. We found evidence of age-based differences in total body length, tail length, skull length, and skull width; however, correcting for age did not have a strong effect on the apparent trends in size over time. Based on linear mixed models, mean total length and tail length increased from 1951-1991, consistent with previous findings. Additionally, our results revealed slight increases in mean skull length and toothrow length over the 40-year study period. There was some indication of differing trends between age classes in both of these measurements. These results were not statistically significant, but our sample size of overwintered adults was relatively small, so further study is needed to fully investigate age-specific size trends in masked shrews. In summary, this thesis highlights the importance of repeatability in body-size research and emphasizes the importance of demography in the study of these trends.
    • Reproduction and stress response endocrinology in blue (Balaenoptera musculus) and gray (Eschrichtius robustus) whales

      Melica, Valentina; Atkinson, Shannon; Mueter, Franz; Tamone, Sherry; Gendron, Diane; DeMaster, Doug (2020-12)
      Identification of biomarkers that reflect physiological status is fundamental for assessing population health, as well as providing more accurate estimates of life history parameters. Blue (Balaenoptera musculus) and gray (Eschrichtius robustus) whale populations feed on lower trophic levels and migrate between the eastern Tropical and the eastern North Pacific Ocean. With increasing disturbances (e.g., changing environment and human activities), understanding the stress response, resultant coping mechanisms, and the subsequent effects on reproduction, is of growing importance. While extensive knowledge is available on photo-identification and ecology of these two species, information on physiology is limited and what exists is outdated. This dissertation validated and measured a suite of steroid hormones in blubber tissue using an enzyme immunoassay technique to develop physiological biomarkers for reproduction and metabolism in these two species. Coupled with sighting history data, progesterone and testosterone were validated as biomarkers for reproductive physiology. In both species, progesterone concentrations were higher in pregnant females and mixture models were developed to estimate reproductive status for whales of unknown status. Testosterone showed greater variability in adult males and concentrations were higher in samples collected during fall, suggesting physiological preparation for mating. Additionally, progesterone concentrations in gray whales were higher in calves of both sexes, indicating maternal transfer through lactation, while in blue whales, testosterone was detectable only in males and in pregnant whales, suggesting its biosynthesis or metabolism is altered during gestation. Biomarkers for stress response were developed through analytical and biological validation of three corticosteroid hormones: cortisol, corticosterone and aldosterone. First, analytical validations (i.e., parallelism and accuracy tests) were used to determine detectability and measurement accuracy of these hormones using commercially available kits. Hormone concentrations were tested for any relationships with life history parameters (e.g., age and reproductive state) as well as with area and time of sampling within presumably "healthy" (biopsies) whales and "stressed" (stranded) whales. "Stressed" whales, especially those that perished due to trauma and/or nutritional stress, had higher concentrations of all three corticosteroid hormones than "healthy" whales, suggesting ongoing alteration of metabolic status due to a stress response. In female "healthy" whales, reproductive status appeared to be a major factor influencing corticosterone concentrations in blue whales and for cortisol in gray whales. Overall, cortisol was determined to be a valid marker for body conditions in both species. These results set a milestone for assisting to better understand the impact of a changing environment on the physiology of these species and can be used to develop more accurate reproductive and survival rates to use in population dynamics models for management of subsistence resources and for conservation of endangered species.
    • The reproductive biology of yelloweye rockfish (Sebastes ruberrimus) in Prince William Sound and the Northern Gulf of Alaska

      Arthur, Donald E.; Falke, Jeffrey; Beaudreau, Anne; Sutton, Trent; Blain-Roth, Brittany (2020-12)
      Over the last half century, Yelloweye Rockfish Sebastes ruberrimus have experienced dramatic declines along the West Coast of the United States and British Columbia. Efforts have been made throughout the species' range to rebuild and sustainably manage stocks, including the introduction of a Statewide Rockfish Initiative by the State of Alaska, which intends to develop management strategies for Yelloweye Rockfish in the Gulf of Alaska. To support this effort and address information gaps in Yelloweye Rockfish reproductive biology throughout their range, I estimated important reproductive parameters and life history information for Yelloweye Rockfish in Prince William Sound and the Northern Gulf of Alaska, Alaska, that included maturity, parturition timing, skip spawning, and fecundity relationships. I identified that ages-at-50% maturity (A50) for males and females were similar (A50 = 15 years and A50 = 16, respectively), but males reached full maturity (A95) earlier than females (male A95 = 19 years and female A95 = 31 years). Female Yelloweye Rockfish fork length-at-50% and 95% maturity (L50 and L95) was greater in the Northern Gulf of Alaska (L50 = 46.7 cm and L95 = 55.8 cm) than in Prince William Sound (L50 = 41.1 cm and L95 = 50.2 cm). Similarly, male L50 and L95 was greater in the Northern Gulf of Alaska (L50 = 44.0 cm and L95 = 49.2 cm) relative to Prince William Sound (L50 = 40.8 cm and L95 = 46.0 cm), and males matured at a smaller size than females. Female L50 was consistent with data from southern populations, but A50 was younger than predicted based on a latitudinal trend, indicating that Yelloweye Rockfish in this region may experience greater than expected growth rates. Yelloweye Rockfish underwent parturition between May and August and peaked in June and July, and parturition timing was earlier for larger and older females. I documented that female Yelloweye Rockfish skip-spawned at a rate of 9.8%. Skip spawning rate was associated with fork length and peaked at sizes between 40.2 cm and 52.3 cm; the peak in stock reproductive potential is shifted toward larger females in response to skip spawning. I conducted egg and larvae counting in an image-analysis software, which was more than four times faster than manual counting and was equally accurate and precise. Yelloweye Rockfish fecundity scaled hyperallometrically with FL and relative fecundity increased with length, indicating that spawning stock biomass may not be proportional to total egg production. Combining these results, I found that ignoring the hyperallometric fecundity relationship and skip spawning could overestimate reproductive potential by as much as 66% and 45% for Prince William Sound and the Northern Gulf of Alaska, respectively. The results of this study will improve the estimates of stock-recruitment dynamics and can be readily integrated into a stock assessment that will guide the sustainable management of Yelloweye Rockfish in Prince William Sound and the Northern Gulf of Alaska.
    • The rocky shores of Prince of Wales, Alaska: intertidal ecology, abalone, and community sustainability

      Bolwerk, Ashley; Eckert, Ginny L.; Carothers, Courtney; Dethier, Megan (2021-05)
      Rocky, nearshore ecosystems are diverse and dynamic environments that function as the link between land and sea and provide important resources for people. In this two-part thesis, I first examined rocky intertidal ecological communities to better understand biotic and abiotic drivers in this system, and then I investigated the abundance of pinto abalone (Haliotis kamtschatkana), a key subsistence resource that local community members identified as the most important because of limited harvest and drastic declines. Pinto abalone are tied to Haida subsistence, culture, and spiritual identity and have been a traditional harvest species for the Haida people for millennia. Pinto abalone were harvested by non-Native fishermen through heavy commercial (1970-1996) and personal use harvest, causing a crash of the population. In the rocky intertidal I surveyed the upper and lower extents of major biobands, frequency of occurrence of sessile organisms, and abundance of mobile invertebrates across a vertical gradient at 18 sites near the west coast of Prince of Wales Island. A multivariate approach was used to identify the major drivers of rocky intertidal community composition and structure. Sea otter (Enhydra lutris) occupation time, average fetch, beach aspect, rugosity, and rock texture were all identified as influential forces for at least one tidal zone and/or biological metrics. Sea otters were not found to restructure the ecosystem, as they do in deeper kelp forest habitats. To assess the current viability of pinto abalone harvest, concerns about sustainability, and their ecological relationships, I partnered with local harvesters within the community of Hydaburg on Prince of Wales Island to combine Indigenous Knowledge about pinto abalone harvest with SCUBA surveys at historically productive traditional harvest sites. Only four (out of 17) of our shallow transects (2 x 20 m), which are within the depth range for traditional harvest methods, had legal-sized pinto abalone (max = 1 abalone). The traditional pinto abalone harvest fishery failed three out of four fishery recovery criteria that were examined. Fourteen out of eighteen sites did not have large (≥ 100 mm) pinto abalone, and pinto large abalone densities were below 0.1 abalone/m2 at all sites. All intermediate size classes of pinto abalone were represented within the fishery, but only 20% of large size classes were observed. Low pinto abalone abundance leads to concerns about traditional harvest viability and spawning failure and thus recruitment failure, for this density-dependent spawning species. In our generalized linear models, pinto abalone presence, density, and biomass were affected by sea urchin biomass. This baseline study of the current state of pinto abalone at traditional harvest sites bestows critical information to a community that depends on pinto abalone as a resource. The Hydaburg Cooperative Association, as a federally recognized Tribe, can use this information to make local management decisions, which include adjustments to harvest guidelines, implementation of sea otter management zones, and/or the establishment of pinto abalone restoration projects. Working with the Tribe and community members throughout the research process led to better science, applicable data, and took a step toward equity and reciprocity in the research processes.
    • Safety analysis of off-highway vehicles use within public rights-of-way in Alaska

      Sayre, Tristan; Belz, Nathan; Barnes, David; Falchetto, Augusto (2020-08)
      Many Alaskans own and operate off-highway vehicles (OHVs) for recreational purposes or for use as primary and secondary modes of transportation. However, the reported crash rate shows that 80 on-road crashes, resulting in five fatalities, occur each year statewide. As a result, the use of OHVs has been identified as a safety concern in the Alaska State Highway Safety Improvement Plan. Minimal research dedicated to understanding OHV use in Alaska exists which limits the potential for improvements that address safety concerns in an equitable fashion. The research presented here contributes to better understanding of on-road OHV use through observational and retrospective analysis. Field-based observations were conducted within highway rights-of-way in 14 strategic locations across Alaska to quantify OHV use and the risk-taking behaviors of riding without helmets, passengers riding without a designated seat, and riding unlawfully on the road. Additional risk factors from the field observations and Alaska Department of Motor Vehicles (DMV) crash data for the period from 2000 through 2016 were identified using the Chi-Square test for independence. Spatial analysis of the Alaska DMV crash data for the period from 2009 through 2016 tested for complete spatial randomness of crashes and identified clusters of crashes by frequency and severity using neighborhood point density statistics. Frequent OHV use was observed with daily traffic volumes exceeding 40 vehicles per day in three field study locations. Several risk-tolerant behaviors were observed including users riding without helmets and vehicles carrying passengers without a designated seat an average of 70 and 20 percent of the time, respectively. Additionally, over half the OHV users were observed to be riding unlawfully using the road. Risk-tolerant behaviors were most frequently observed in communities where on-road use is legal and happened to be coincident with the highest on-road use rates. Overrepresented risk factors for high crash severity incidents included riding at night, in summer, on unpaved roads, on local roads or collectors, in rural areas, for single-vehicle crashes with the occupant not using safety equipment and riding under the influence of alcohol. Crashes were observed to be clustered around towns with the highest frequencies occurring near town centers. The prevalence of risk-tolerant riding behaviors and unlawful on-road riding indicates the need for improvements to existing laws and the education and enforcement thereof. Changes must address the unique needs of users while also considering local jurisdiction such that safety can be improved while also maintain transport equity for residents of rural and isolated communities in Alaska.
    • Salmonid distribution models to support restoration planning across the fragmented Chehalis River basin, WA

      Walther, Eric J.; Westley, Peter; Zimmerman, Mara; Falke, Jeffrey; Seitz, Andrew (2021-05)
      Understanding the factors that influence the distribution of species through time and across space is a fundamental goal of ecology and crucial information needed to effectively manage and recover populations. Anthropogenic fragmentation of habitat disrupts ecological processes and is an on-going threat to species persistence across taxa. River ecosystems are particularly vulnerable to disruptions in connectivity and are the focus of extensive restoration efforts and financial investment. For example, over $300 million/year is invested towards restoration in the Columbia River basin. However, restoration is often impeded by knowledge gaps in distribution that can result in omitting locations that would benefit from restoration. For mobile species within dendritic freshwater networks, the boundary that demarcates the total quantity of available habitat can be defined by the upper limit of occurrence (ULO) and is a useful metric for assessing the extent of habitat to consider for restoration. The first goal of this work was to identify the ULO boundary for three socially and ecologically important anadromous fishes (Oncorhynchus spp.) in a subset of representative streams across a complex river network in southwestern Washington State, USA, and quantify the relationship of the ULO with landscape attributes for these species. Extensive field surveys covering 669 river km across two years documented the ULO in 115 terminal streams (i.e., uppermost independent stream segment within a stream network) for coho salmon (O. kisutch), 97 terminal streams for steelhead trout (O. mykiss), and 57 terminal streams for chum salmon (O. keta). The landscape attributes associated with these ULO locations varied among species. For example, precipitation was an important predictor only for coho salmon, whereas slope was an important predictor only for steelhead trout. In contrast, drainage area, elevation, and geology were important predictors for all species; while the direction was the same for drainage area and elevation, the magnitude of the effect of each landscape attribute varied among species. I demonstrated that large-scale landscape attributes can accurately and consistently detect species-specific distribution boundaries across broad and diverse habitat (percent correct classification:78%-89%; area under the receiver operating characteristic curve: 0.87-0.96). The ability to quantify landscape attributes related to distribution boundaries illuminates how the biology and life history of a species is captured across the landscape. The second goal of this work was to predict the range of occurrence as a function of landscape attributes for coho salmon, steelhead trout, and chum salmon across a range of probability decision thresholds, that reflect different risk-tolerance scenarios and determine whether stream reaches are within or outside the range of occurrence. Generalized linear mixed models were used to compare the quantity of currently described distribution used in restoration planning in the basin and quantify the amount of habitat inaccessible due to anthropogenic barriers. The change in amount of habitat within the predicted range of occurrence across probability decision thresholds ranged from 60%-74% among species. Differences between the model predictions and the currently described distribution for each species ranged from -14% to 171%, which on a whole indicates that the amount of habitat being considered for restoration is currently underestimated. As predicted, species with a greater range of occurrence (e.g., coho salmon) had a greater percentage of predicted suitable habitat inaccessible due to anthropogenic barriers (coho salmon:17.4%-28.8%, 0.75-0.25 PDT; steelhead trout:10.2%-17.5%; chum salmon: 3.9%-12.3%), and the locations of these barriers varied among species. Modelling species distributions at multiple levels of risk-tolerance allows practitioners to weigh the ecological benefits and financial investment when considering locations for restoration. Ultimately, the effective consideration of restoration actions requires tools such that managers can weigh the trade-offs of their decisions given that not all actions equitably benefit all species.
    • Sea otter diet composition with respect to recolonization, life history, and season in southern Southeast Alaska

      LaRoche, Nicole; Pearson, Heidi C.; Eckert, Ginny L.; Miller, Todd (2020-12)
      Until translocation efforts in the 1960s, sea otters (Enhydra lutris) were absent from Southeast Alaska due to extirpation by the fur trade in the 18th and 19th centuries. About 400 sea otters were reintroduced to six Southeast Alaska locations, including two sites near Prince of Wales Island in southern Southeast Alaska. The most recent US Fish and Wildlife Service population count, completed in 2012, estimated that about 25,000 sea otters inhabited Southeast Alaska. Sea otters will reduce invertebrate prey biomass when recolonizing an area. By quantifying sea otter diets and caloric intake according to recolonization patterns, we can better understand the ecosystem impacts of sea otter population increase and range expansion. The goal of this study was to quantify changes in seasonal diet composition and assess the energetic quality of sea otter prey in southern Southeast Alaska. I made visual foraging observations of 3,385 sea otter dives around Prince of Wales Island (POW) to determine diet composition during the spring and summer months. I then collected vibrissae from 45 sea otters obtained from subsistence hunters to assess year-round sea otter diets using stable isotopes. I collected sea otter prey items throughout POW in three seasons (May 2018, August 2018, and February 2019) to measure energy, lipid and protein content, and delta¹³C (carbon) and delta¹⁵N (nitrogen) values. Sea otter diets mainly consisted of clams, as quantified both from visual observations and stable isotope analysis. However, there was more variation in the diet estimates from stable isotope analysis. Stable isotope analysis revealed variation among individual diets of sea otters and individuality in diet within the POW region of sea otters. Sea otters seasonally increased consumption of some prey when the prey was highest in lipid and overall caloric content. Sea otters switched prey types when the prey was more energetically valuable. The results of this study will aid in future management of shellfisheries, subsistence hunting, and implementing co-management of a protected species by providing quantitative diet composition data for stakeholders. This work is a part of a large-scale project examining how the recovery of sea otters structures nearshore marine ecosystems, provides ecosystem services, and affects community sustainability.
    • Sea otters in Southeast Alaska: subsistence harvest and ecological effects in seagrass communities

      Raymond, Wendel W.; Eckert, Ginny L.; Beaudreau, Anne H.; Galloway, Aaron W.E.; Mueter, Franz J. (2020-08)
      The recovery of sea otters (Enhydra lutris) to Southeast Alaska is a conservation success story, but their increasing population raises questions about sea otter population dynamics and the ecological role of this top-level predator. In Chapter 1, we addressed these questions by investigating patterns and population effects of subsistence sea otter harvest. Subsistence harvest reduced populations at a small scale, with potential to slow or stop population growth, but across Southeast Alaska the population continues to grow, even with an average 3% subsistence harvest rate. In Chapters 2 and 3 we investigated the ecological role of sea otters in seagrass (Zostera marina) communities. When we tested for generality in a sea otter - seagrass trophic cascade across a large spatial scale in Southeast Alaska, we found a positive relationship between sea otters and seagrass. However, we found no evidence of a relationship between crabs and epifauna, suggesting that the ecological mechanisms in Southeast Alaska may differ from other regions. Our comparison of carbon and nitrogen stable isotopes (SI) to assess the role of sea otters on trophic structure and energetic pathways of seagrass beds found little effect of sea otters in overall community trophic niche space, suggesting similar carbon sources and food chain length in seagrass meadows regardless of sea otters. Conversely, the FA profiles of diverse consumer suggest variation in dietary sources with and without sea otters. This result suggests that the trophic cascade may not be the only or primary energetic pathway in Southeast Alaska seagrass communities. In all, our studies have revealed that sea otters in Southeast Alaska are linked to both people and a common Southeast Alaska nearshore habitat, seagrass. These results describe the varied interactions of a recovering top predator and highlight a need to consider these diverse interactions in resource management, conservation, and ecological research.
    • Sea urchin ecology: effects of food-web modification, climate change, and community structure

      Weitzman, Benjamin P.; Esler, Daniel; Konar, Brenda H.; Hardy, Sarah M.; Johnson, Mark A.; Tinker, Martin T. (2020-08)
      Ecosystem structure and function of temperate rocky reef habitats are subject to change as a result of food-web modification, climate change, and changes in biological community interactions. Sea urchins are a global driver of change in nearshore marine habitats though their ability to heavily graze marine vegetation and force rocky reef ecosystems from kelp forest to sea urchin barren ground states. The Aleutian Archipelago in southwest Alaska provided an ideal natural laboratory to study sea urchin (Strongylocentrotus spp.) ecology following the functional loss of the keystone predator, the sea otter (Enhydra lutris) during the 1990s. The objectives of this dissertation were to 1) determine the important drivers of sea urchin demographics following the functional loss of their keystone predator; 2) determine how projected ocean warming and acidification may affect sea urchin physical condition; and 3) identify biological drivers of sea urchin recruitment in both kelp forest and barren ground habitats. To determine demographic drivers, I used a time series of benthic habitat, sea urchin demographic, and environmental data, dating back almost forty years. In the absence of sea otters, environmental conditions, specifically ocean temperatures, became more important to sea urchin demographics, but recruitment was the primary process affecting the resultant abundance and size class structure over time. To understand how predicted ocean warming and acidification could impact S. polyacanthus survival, growth, calcification, gonad development, and energy content, a 108-day laboratory experiment was conducted. This experiment determined that temperature caused a greater reduction in survival than acidification, and that projected changes in temperature and acidification will result in investment trade-offs between reproduction and maintenance or growth of somatic and calcified tissues. To determine how recruitment varied between kelp forest and sea urchin habitats, fine-scale surveys of benthic community structure found that specific taxa, and not overall community structure, correlated with sea urchin recruitment. Results from this dissertation will allow managers to make predictions about how sea urchin demography will change as a result of keystone predator loss and climate change and how that will affect nearshore community structure and function. Overall, my dissertation establishes likely pathways by which coastal habitats may change over time, in a system no longer under strong top-down control.
    • Seasonal variation in nutritional biomarkers and fecal cortisol concentrations in a northern population of snowshoe hares

      Montgomerie, Claire Kornet; Kielland, Knut; Breed, Greg; Lian, Marianne (2020-08)
      Blood biomarkers indicative of nutritional status, fecal cortisol metabolite concentrations and an established body condition index (BCI), were collectively examined from snowshoe hares(Lepus americanus) inhabiting northern Alaska in 2018, during five ecologically significant times of year. As a novel approach to increase our understanding of the effects of diet and predation pressure on hare physiology, I addressed how these markers were associated with seasonal timing of energetic demands and adult survival rates. Mean decreases in concentrations of total protein (TP), blood urea nitrogen (BUN), hematocrit (HCT) and glucose during spring and autumn, suggest that snowshoe hare nutritional status decreased during these two seasons in 2018. The shoulder seasons of spring and autumn coincide with energetic challenges, including molt, changes in diet and breeding. Because available forage during these seasons largely consists of winter-dormant twigs, the energy expenditure of growing a new winter coat (autumn) and breeding behavior (spring) may compromise the energy balance of hares during these periods. Male hares, whose activity levels increase during breeding, exhibited lower BCI scores and were slower to molt from white to brown than female hares in May. Furthermore, adult survival rates were lowest during spring months. Snowshoe hare mean fecal cortisol metabolite concentrations did not show associations with seasons of apparent low nutritional status. Adult hare survival rates peaked during summer and early autumn, during which mean values of TP, BUN, Hct, Cl (chloride), Na (sodium) and glucose also increased. By contrast, this period coincided with a 2-fold increase in mean fecal cortisol metabolite concentrations, suggesting that the apparent stressor was not related to nutrition. Interestingly, after having decreased in autumn, BUN, Hct, TP, and glucose mean concentrations increased in midwinter. Free calcium (iCa) and potassium (K) mean concentrations were also highest in December. Hares may have reduced activity during winter months, and metabolic rates may have increased to cope with thermoregulation demands. BCI scores decreased by December, suggesting use of endogenous reserves. Lowest seasonal mean cortisol metabolite concentrations were also observed in mid-winter. This study demonstrates the value of examining both physiological and morphological metrics of snowshoe hare condition to better our understanding of how seasonal trends in food and fear may unfold into cyclic patterns.
    • Sled dogs as a model for studying dietary vitamin D

      Striker, Kali; Dunlap, Kriya; Jerome, Scott; Drew, Kelly (2021-05)
      Vitamin D deficiency (VDD) has become a pandemic and has shown to be correlated with several poor health outcomes. Many factors that lead to VDD are environmental and lifestyle. Vitamin D has physiological implications involved in all areas of human health and is also important for animal health. Canines have shown adverse health outcomes similar to humans that correlate with vitamin D deficiency such as chronic kidney disease (CKD) and irritable bowel disease (IBD). Canine vitamin D requirements are largely unknown due to the lack of research and the wide ranges of supplementation throughout dog food manufacturers. Pre-active plasma vitamin D metabolites are used as the biomarker of vitamin D status in humans and dogs but may not be representative of overall vitamin D status. Therefore, other biomarkers representing vitamin D status are often used in conjunction to determine physiological relevance. To address this gap in knowledge, this study used parathyroid hormone concentrations as well as vitamin D binding protein concentrations to establish more of an overall status of vitamin D. In canines, clinical supplementation following VDD is usually administered orally with vitamin D olive oil tablets; however, supplementation is usually unsuccessful. Vitamin D and its metabolites are lipid soluble and stored in adipose tissue. Although few foods provide appreciable levels of vitamin D, wild salmon contain some of the highest dietary vitamin D levels. People living in Alaska are at an increased risk of VDD due to reduced zenith sun angles for much of the year. Consequentially sufficient vitamin D levels need to be acquired through diet or supplementation. Historically, Alaska Natives obtained sufficient amounts of vitamin D from traditional subsistence foods, but with the progressive shift away from these foods VDD has increased in Alaskan populations. The limited research available suggests that Alaskan sled dogs in particular are a group found to be generally VDD. Sled dogs are an important part of the traditional Alaska subsistence lifestyle and have evolved alongside humans in the circumpolar north. Sled dogs, therefore, provide a valuable model for studying health outcomes associated with VDD in both people and dogs in the far north. This study provides significant evidence showing wild Alaskan salmon as a dietary source of supplementation to raise 25(OH)Vitamin D serum in dogs after only 4 weeks. We also show significance in variation by confounding factors, age and sex.