• The ecology of the Arctic char and the dolly varden in the Becharof Lake drainage, Alaska

      Scanlon, Brendan P. (2000-12)
      Becharof Lake is home to both Arctic char (Salvelinus alpinus) and the closely related Dolly Varden (Salvelinus malma), two species known not only to be similar in appearance but also to exhibit similar life histories. The body morphometry, otolith microchemistry, and stomach contents of both species were studied in fish collected from May to September 1998. Morphometric and meristic analysis revealed clear separation in body structure between the two species, as well as potential sub-populations within each species. Otolith microchemistry revealed incidences of anadromy and non-anadromy in both species. Stomach content analysis revealed a broad feeding niche but smaller ranges in food types in individual Arctic char with little seasonal preference, whereas Dolly Varden showed seasonality in food choices. Data suggest that both species can move in and out of the lake system, and that little competition for food or habitat occurs between the two species in the summer months.
    • The ecology of wolverines in southcentral Alaska

      Gardner, Craig L. (1985-05)
      A study of wolverine (Gulo gulo) ecology was conducted within the upper Susitna Basin in south central Alaska between May 1980 and April 1982. The study was initiated in an attempt to identify potential impacts of hydroelectric development on the wolverine populations. Twelve wolverines (10 males) were fitted with radio transmitters and relocated 153 times. The mean winter and summer home ranges for adult males were 353 km2 and 385 km2, respectively. Adult male home ranges were primarily mutually exclusive, having an average overlap of 4.2% between neighbors. On an annual basis, wolverines appeared to select spruce cover types; this selection was strongest during the winter. The most important foods to wolverines were carrion of ungulates (winter) and ground squirrels (summer). The wolverine population in the Susitna Basin during the study period was not heavily exploited by man and was secure.
    • Effects of antimony mining on stream invertebrates and primary producers in Denali National Park, Alaska

      Wedemeyer, Kathleen (1987-12)
      Heavy metals, primarily antimony, arsenic and manganese from antimony mines in Denali National Park, Alaska impacted all levels of the stream ecosystem. Decreased algal, moss and macroinvertebrate abundance (but not changes in macroinvertebrate trophic organization) were all clearly associated with mining activity in Slate and Eldorado creeks. Crustacea, Chironomidae (Diptera), Hydracarina (Arachnida), Nemouridae (Plecoptera), and Zapada (Nemouridae) decreased in relative abundance with metal pollution while Capniidae (Plecoptera), Nemoura (Nemouridae), and Podmosta (Nemouridae) increased in relative abundance at mine sites. The data from Stampede Creek demonstrated that mineralized but unmined stream reaches may be impacted by heavy metals. Unexpectedly higher selenium levels upstream of the mine may account for the general lack of substantial differences in macroinvertebrates and periphyton upstream and downstream of the mine. However, macroinvertebrate and periphyton abundances were lower at both sites on Stampede Creek than at the unmined control stream, Jumbo Creek.
    • The effects of barotrauma and deepwater-release mechanisms on the reproductive viability of yelloweye rockfish in Prince William Sound, Alaska

      Blain, Brittany; Sutton, Trent; Seitz, Andrew; Erickson, Jack (2014-12)
      Previous research has shown that releasing sport-caught Yelloweye Rockfish Sebastes ruberrimus with a deepwater-release mechanism (DRM) can alleviate anatomical damage due to barotrauma. However, it is unknown if a Yelloweye Rockfish remains a viable member of the population and reproduces in subsequent years following a barotrauma event and recompression with a DRM. The objectives of my study were to: 1) determine if Yelloweye Rockfish were able to reproduce one to two years following known forced decompression and recompression event(s); and 2) evaluate if barotrauma and recompression affected the quality of developing embryos. In 2010, Yelloweye Rockfish were sampled from an isolated reef in Prince William Sound, Alaska. Fifteen females tagged in 2008 and 2009 were recaptured in 2010, and reproductive status was identified by visual observation of the gonads and hematological sampling (i.e., vitellogenin and calcium²⁺ plasma concentrations). Oil globule volume, percent lipid, and caloric content were also measured for the embryos from seven of these females and these values were compared to embryos from 13 females with no previously documented barotrauma and recompression events. These results showed that all 15 Yelloweye Rockfish recaptured in 2010 were gravid (with eggs) or spent (having released eggs). In addition, there were no differences in median oil globule volume, caloric content, and percent lipid between individual embryos from new captures and recaptures. Results indicated that there is no evidence that reproduction and embryo quality of Yelloweye Rockfish is adversely affected one to two years following forced decompression and recompression with a DRM at the depths sampled in this study. This research provides information on the utility of DRMS as a tool for rockfish conservation and supports the importance of utilizing these devices by sport anglers.
    • Effects of bear viewers and photographers on brown bears (Ursus arctos) at Hallo Bay, Katmai National Park and Preserve

      French, Howard Blair (2007-05)
      We investigated the effects of bear viewing and photography on brown bears (Ursus arctos) that used open habitats at Hallo Bay, Katmai National Park and Preserve (KNPP), Alaska. We also investigated how bear use of the area varied with season, human presence, and time of day. We found that the mean number of bears present varied significantly with season, time of day, and human presence. There were significantly more bears present before the salmon season than during the salmon season; bear numbers increased significantly during the day, and there were significantly more bears when humans were present. Humans at varying distances least affected activity budgets of sows with spring cubs, but foraging efficiency (bites per minute) of sows with spring cubs was significantly lower with humans <50 m away than with humans absent. Fishing success (chases per catch) of large males and single bears was lower when humans were present, but fishing success of sows with spring and older cubs was higher when humans were present. We conclude that humans are affecting brown bears that use Hallo Bay and therefore the Katmai NPP Bear Management Plan is being violated as well as the act establishing the National Park Service. We recommend that managers at KNPP restrict visitor use at Hallo Bay and enforce existing policy.
    • Effects of elevated sediment levels from placer mining on survival and behavior of immature arctic grayling

      Scannell, Patrick O. (1988-12)
      The effect of placer mining effluents on Arctic grayling (Thymallus arcticus) fingerling and egg survival was tested in mined and unmined streams in interior Alaska. Also the influence of turbidity on Arctic grayling reactive distance and avoidance behavior was tested in a laboratory choice chamber. Arctic grayling fingerlings suffered less than 1% mortality during a 96-hr toxicity test in both clear (mean NTU = 1.4) and mined (mean NTU = 445) streams. Arctic grayling eggs did not show significantly (p > 0.1) higher mortality in mined streams than in unmined streams. In a laboratory choice chamber test, Arctic grayling avoided water with a turbidity above 20 NTU (nephelometric turbidity units). Arctic grayling reactive distance diminished proportional to the natural logarithm of turbidity.
    • Effects of fish wheels on fall chum salmon (Oncorhynchus keta): non-esterified fatty acids and plasma indices of stress

      Cleary, Peter Mallon (2003-05)
      The effect of tagging and capture on plasma concentrations of cortisol, glucose, lactate, chloride, and non-esterified fatty acids (NEFA) in chum salmon was investigated. Adult chum salmon were captured in August-September 2000 and 2001 with a fish wheel on the lower Kantishna River. Tagged and untagged fish were subsequently captured on the lower Toklat River and sampled for blood. Tagged fish (males and females) at the Toklat recovery fish wheels had lower (P <0.04) plasma cortisol concentrations than untagged fish. Glucose concentrations were lower (P = 0.03) in tagged than untagged males but did not differ between tagged and untagged females. Lactate and chloride concentrations did not differ between tagged and untagged fish. Tagged chum salmon captured at the Toklat River recovery wheels had lower concentrations of NEFA (P = 0.02). Taken together, these results suggest there is a metabolic cost from capture and tagging using fish wheels.
    • The effects of intense fire on headwater streams of the Colville National Forest, WA

      Mellon, Cassie Danielle (2006-12)
      Forest fires play an important role in shaping ecosystems, and there has been growing concern on the effects of high intensity fires on forest and aquatic ecosystems. Headwater streams are highly connected to riparian and surrounding terrestrial systems, and to downstream aquatic systems, partly through prey and organic matter transfers via aquatic invertebrate drift and emergence. Because of their small size, headwater streams may experience the greatest initial impact from forest fire, but may also return to pre-fire conditions quicker than larger streams. In this study, headwater streams from replicated burned and control watersheds were sampled in the two years following an intense forest fire in northeastern Washington. Benthic, drift and emergence samples of aquatic invertebrates were taken and analyzed for differences in density, biomass and community composition between watershed types. There was significantly higher density of invertebrates in burned sites, but no difference in biomass except in invertebrate emergence which was greater at burned sites. There was lower diversity in the burned watersheds, and the invertebrate community was dominated by chironomids. These changes in invertebrate density and community composition could influence the food resources available to aquatic and riparian consumers.
    • Effects of migratory geese on plant communities and nitrogen dynamics in an Alaskan salt marsh

      Zacheis, Amy Beach; Ruess, Roger; Hupp, Jerry; Schwaegerle, Kent; Sedinger, James (2000-12)
      Herbivory is an integral component of ecosystems that impacts plant communities and ecosystem processes, and affects forage availability and quality for the herbivore. I investigated the effects of lesser snow geese (Anser caerulescens caerulescens) and Canada geese (Branta canadensis) on two salt marsh communities, a sedge meadow and an herb meadow, in Cook Inlet, Alaska. Geese used the marshes during spring migration for a brief period, and foraging intensity was low compared to other goose-grazing systems. Seventy percent of the snow goose diet was on belowground plant tissues, whereas 92% of the Canada goose diet was on aboveground shoots. In the sedge meadow, where feeding was primarily on aboveground shoots, there was no effect of grazing on biomass of the dominant species Carex ramenskii and Triglochin maritimum, or on shoot nitrogen concentrations in these species (an index of forage quality). An experiment with captive geese found no effect of herbivory on biomass or nitrogen concentrations at foraging intensity ten times greater than that imposed by wild geese, indicating that this community is highly resilient to herbivory. In the herb meadow, where snow geese fed on belowground tissues, biomass of Plantago maritima and Potentilla egedii was lower, and biomass of Carex ramenskii higher, on grazed compared to ungrazed plots. Plant species' response to herbivory was determined by plant growth form, the type of herbivory (above- or belowground), and competitive interactions. Light herbivore pressure in this community altered the relative abundance of forage species for geese. In the sedge meadow community, geese increased nitrogen mineralization rates by trampling litter into wet soils. Litter incorporated into soils increased organic nitrogren pool size, decreased soil C:N ratios, and facilitated the growth of nitrogen-fixing cyanobacteria, all of which led to increased mineralization rates in grazed areas. Fecal nitrogren inputs were small and did not affect nitrogen availability. A captive goose experiment found that fecal additions ten-fold larger also had no effect on nitrogen availability. In the herb meadow, geese did not affect nitrogen mineralization because soils were dry with little standing water, so that incorporation of litter into soils through trampling was less important.
    • Effects of milk intake, growth and suckling efficiency on suckling behavior of muskox (Ovibos moschatus) calves

      Tiplady, Barbara Ann (1990-12)
      General theory on parental provisioning predicts that mammalian offspring receiving more milk should show longer suckling bouts, greater total suckling time, longer intervals between bouts, and greater suckling success. For muskoxen I found that suckling bout duration and suckling success were positively correlated with milk intake during some but not all stages of lactation. Neither interval between suckling bouts, nor total suckling time, was correlated with milk intake. Growth of calves was positively related to milk intake, and among calves of the same age suckling efficiency (intake/min suckling) was highly related to body weight. Therefore, milk intake affects growth rate, which in turn affects suckling efficiency. The overriding influence of calf body size and suckling efficiency limits interpretation of differences in suckling behavior that can be attributed to milk intake by muskox calves and therefore to the provisioning strategy of the cow.
    • The effects of permafrost degradation on soil carbon dynamics in Alaska's boreal region

      O'Donnell, Jonathan A. (2010-12)
      High-latitude regions store large quantities of organic carbon (C) in permafrost soils and peatlands, accounting for nearly half of the global belowground C pool. Projected climate warming over the next century will likely drive widespread thawing of near-surface permafrost and mobilization of soil C from deep soil horizons. However, the processes controlling soil C accumulation and loss following permafrost thaw are not well understood. To improve our understanding of these processes, I examined the effects of permafrost thaw on soil C dynamics in forested upland and peatland ecosystems of Alaska's boreal region. In upland forests, soil C accumulation and loss was governed by the complex interaction of wildfire and permafrost. Fluctuations in active layer depth across stand age and fire cycles determined the proportion of soil C in frozen or unfrozen soil, and in turn, the vulnerability of soil C to decomposition. Under present-day climate conditions, the presence of near-surface permafrost aids C stabilization through the upward movement of the permafrost table with post-fire ecosystem recovery. However, sensitivity analyses suggest that projected increases in air temperature and fire severity will accelerate permafrost thaw and soil C loss from deep mineral horizons. In the lowlands, permafrost thaw and collapse-scar bog formation resulted in the dramatic redistribution of soil water, modifying soil thermal and C dynamics. Water impoundment in collapse-scar bogs enhanced soil C accumulation in shallow peat horizons, while allowing for high rates of soil C loss from deep inundated peat horizons. Accumulation rates at the surface were not sufficient to balance deep C losses, resulting in a net loss of 26 g C m⁻² y⁻¹ from the entire peat column during the 3000 years following thaw. Findings from these studies highlight the vulnerability of soil C in Alaska's boreal region to future climate warming and permafrost thaw. As a result, permafrost thaw and soil C release from boreal soils to the atmosphere should function as a positive feedback to the climate system.
    • Effects of recreational disturbance on breeding black oystercatchers: species resilience and conservation implications

      Morse, Julie Anne (2005-12)
      The potential conflict between increasing recreational activities and nesting birds in coastal habitats has raised concerns about the conservation of the black oystercatcher (Haematopus bachmani). To address these concerns, I studied the breeding ecology of black oystercatchers in Kenai Fjords National Park and examined the impact of recreational disturbance on breeding parameters. Most recreational disturbance of breeding territories was from kayak campers and occurred after June 13, the peak hatch of first clutches. Mean annual fledging success (24%) was low, but the results suggest that daily survival rates of nests and broods did not differ between territories with and without recreational disturbance. Nest survival varied annually and seasonally, and declined during periods of extreme high tides. Daily survival rate of broods was higher on island territories than mainland territories, presumably due to differences in predator communities. Most (95%) color-banded oystercatchers returned to their breeding territories in the subsequent year regardless of level of disturbance. On average, black oystercatchers decreased incubation constancy by 39% in response to experimental disturbance. However, I found no evidence that time off the nest was associated with probability of nest survival. Further, I found no evidence that oystercatchers habituated to recreational activity. The data suggest that black oystercatchers in Kenai Fjords National Park are resilient to the current low levels of recreational disturbance.
    • Effects of sample size and ageing error on estimates of sustained yield

      Coggins, Lewis G.; Quinn, Terrance J. II; Hasbrouck, James J.; Haldorson, Lewis J.; Reynolds, James B. (1997-12)
      A Monte Carlo simulation model of an exploited age-structured fish population was constructed, to evaluate the effects of sampling and ageing the catch on estimates of population parameters from catch-age analysis with auxiliary information and resultant estimates of sustained yield. A factorial experimental design was used where input parameters were varied among: small (100), medium (300) and large (900) catch sample sizes; high and low levels of ageing precision; and a range of ageing biases. Ageing bias and precision had dramatic effects on estimated sustained yield: positive ageing bias and ageing imprecision generally caused under-estimation of sustained yield, while negative ageing bias caused over-estimation of sustained yield. The multiple reader/reading ageing scenarios designed to mitigate ageing error were able to reduce the affects of ageing imprecision, but were unable to alleviate the problems associated with ageing bias. The simulation model can be modified for a variety of recreational fish populations; a diskette and user manual are available.
    • Environmental and evolutionary processes affecting population dynamics and life-history of arctic grayling in western and Interior Alaska

      Neyme, Jenny Lou (2005-08)
      I compared the life-history and population dynamics of arctic grayling Thymallus arcticus in western and Interior Alaska. Fish in western Alaska grew rapidly to a large maximum size, adult mortality rates were low and juvenile mortality rates were high. As a result, western populations consisted mainly of larger, older fish. Fish in Interior streams grew more slowly to a smaller maximum size, adult mortality rates were higher and juvenile mortality rates lower than in western streams. As a result, Interior populations consisted mainly of smaller, younger fish. The relationship between body size and ovary mass was similar between regions, but Interior fish allocated a greater proportion of their annual energy budget to reproduction. I also used a foraging model to test the hypothesis that regional differences in drift-feeding opportunities were responsible for faster growth and larger size in arctic grayling in western Alaska and to determine the relative contribution of invertebrate drift density and physical habitat characteristics to regional differences in profitability. The model predicted that drift-feeding would be more profitable in western Alaska and that regional differences in invertebrate drift density and size composition were responsible for this difference.
    • Environmental drivers of deer population dynamics and spatial selection in Southeast Alaska

      Gilbert, Sophie L.; Hundertmark, Kris; Boyce, Mark; Lindberg, Mark; Person, David (2015-08)
      The coastal temperate rainforest is one of the rarest ecosystems in the world, and a major portion of the global total is found in Southeast Alaska. In this ecosystem, Sitka black-tailed deer are the dominant large herbivore, influencing large carnivores that prey on deer such as wolves and bears, as well as plant species and communities through browsing. In addition, deer play an important economic and cultural role for humans in Southeast Alaska, making up the large majority of terrestrial subsistence protein harvested each year as well as providing the backbone of a thriving tourism industry built around sport hunting. Given the importance of deer in this system, there remain a surprisingly large number of key gaps in our knowledge of deer ecology in Southeast Alaska. These knowledge gaps are potentially troubling in light of ongoing industrial timber-harvest across the region, which greatly alters habitat characteristics and value to wildlife. This dissertation research project was undertaken with the aim of filling several connected needs for further understanding deer ecology, specifically 1) patterns of reproduction and fawn survival, 2) population dynamics in response to environmental variability, and the underlying drivers of spatial selection during 3) reproduction and 4) winter. To fill these knowledge gaps, I developed robust statistical tools for estimating rates of fawn survival, and found that fawns must be captured at birth, rather than within several days of birth, in order to produce unbiased estimates because highly vulnerable individuals died quickly and were thus absent from the latter sample. I then use this robust approach to estimate vital rates, including fawn survival in winter and summer, and developed a model of population dynamics for deer. I found that winter weather had the strongest influence on population dynamics, via reduced over-winter fawn survival, with mass at birth and gender ratio of fawns important secondary drivers. To better understand deer-habitat relationships, I examined both summer and winter habitat selection patterns by female deer. Using summer-only data, I asked how reproductive female deer balance wolf and bear predation risk against access to forage over time. Predation risks and forage were strong drivers of deer spatial selection during summer, but reproductive period and time within reproductive period determined deer reaction to these drivers. To ensure adequate reproductive habitat for deer, areas with low predation risk and high forage should be conserved. Focusing on winter, I evaluated deer spatial selection during winter as a response to snow depth, vegetation classes, forage, and landscape features. I allowed daily snow depth measures to interact with selection of other covariates, and found strong support for deer avoidance of deep snow, as well as changes in deer selection of old-growth and second-growth habitats and landscape features with increasing snow depth. Collectively, this dissertation greatly improves our understanding of deer ecology in Alaska, and suggests habitat management actions that will help ensure resilient deer populations in the future.
    • Estimation of abundance and mortality of emigrating chum salmon and chinook salmon in the Chena River, Alaska

      Peterson, Brent David (1997-05)
      During May-June, 1995 and 1996, the outmigration of juvenile chum salmon (Oncorkynchus keta) and chinook salmon (O. tschazvytscha) was sampled with floating traps in the area of the Chena River Lakes Flood Control Project, Chena River, Alaska. Catch-per-unit-effort (CPUE) was higher at night than day for chinook juveniles, but not for chum juveniles. CPUE of both species decreased as the season progressed, but usually increased during higher-discharge events. CPUE is standardized by time; discharge was monitored as a covariate but was not included in CPUE calculations. The Jolly-Seber family of models was used on recapture data of fin-dipped fish to obtain estimates of abundance and survival in 1996. Abundance estimates were 266,104 chum salmon (95% Cl 128,031 - 404,177) and 171,952 chinook salmon (95% Cl 146,342 - 197,561) during the May-June outmigration period. These abundance estimates are probably underestimates of the entire Chena River population. Survival estimates were 0.135 (95% Cl 0.042 - 0.228) for chum salmon and 0.713 (95% Cl 0.492 - 0.935) for chinook salmon over the same period.
    • Evaluating the hooking injury and immediate physiological response of wild rainbow trout to capture by catch-and-release angling

      Meka, Julie M. (2003-08)
      Rainbow trout from the Alagnak River watershed, Alaska, were captured by angling to determine the types of terminal gear contributing to hooking injury and the physiological response to angling based on concerns over high incidences of hooking injuries and the physiological impact of multiple recaptures on individual fish. Landing and hook removal times were recorded for a portion of fish captured, and plasma cortisol, glucose, ions (sodium, chloride, potassium), and lactate were evaluated in fish following capture to document physiological changes in relation to capture duration. The majority of new injuries resulted when fish were captured using barbed J hooks, and barbed J hooks took longer to remove than barbless hooks. Fish were hooked internally more frequently when captured with J hooks compared to circle hooks, but similar overall hooking injury rates were observed for both hook types. Novice anglers injured proportionally more fish than experienced anglers, and experienced anglers took longer to land fish than novice anglers. Plasma cortisol and lactate increased significantly with increasing landing and handling times. Fish captured at cooler water temperatures had significantly lower cortisol and lactate concentrations than fish caught at warmer temperatures indicating that water temperature influenced the magnitude of the physiological response.
    • Evaluation of wolf density estimation from radiotelemetry data

      Burch, John W. (2001-05)
      Density estimation of wolves (Canis lupus) requires a count of individuals and an estimate of area those individuals inhabit. With radiomarked wolves, the count is straightforward but estimation of area is more difficult and often given inadequate attention. The population area, based on the mosaic of pack territories, is influenced by sampling intensity similar to individual home ranges. If sampling intensity is low, population area will be underestimated and wolf density will be inflated. Using data from studies in Denali National Park and Preserve, I investigated these relationships using Monte Carlo simulation to evaluate effects of radiolocation effort and number of marked packs on density estimation. As the number of adjoining pack home ranges increase, fewer relocations are necessary to define a given percentage of population area. I evaluated the utility of nonlinear regression to adjust for biases associated with under sampling and present recommendations for monitoring wolves via radiotelemetry.