• Ecological and physiological aspects of caribou activity and responses to aircraft overflights

      Maier, Julie Ann Kitchens (1996)
      I investigated the use of remote-sensing of caribou (Rangifer tarandus) activity to assess disturbance of low-altitude overflights by jet aircraft. Resource management agencies are concerned about the potential effects of these overflights on important species of ungulates. I hypothesized that low-altitude overflights would affect activity and movements of caribou, and thereby constitute a disturbance with negative consequences on energetics. I used caribou of the Delta Herd (DCH) and captive animals at the Large Animal Research Station (LARS) to address the hypotheses: caribou (1) exhibit equal activity day and night; (2) do not time activity to light; and (3) activity patterns do not change seasonally in response to daylength. Caribou were nychthemeral and exhibited uniform activity with no apparent timing to light. DCH caribou responded to seasonal changes in the environment by modifying activity (increased activity in response to insect harassment), whereas LARS caribou altered activity in response to fluctuating physiological variables (increased activity during rut). Changes in daylength did not affect activity. Data on activity from LARS and DCH caribou were compared with extant data on caribou of the Denali and Porcupine herds. Poor quality forage in winter was inferred from long resting bouts, and low availability of forage was inferred from long active bouts of post-calving caribou of the DCH. In midsummer, caribou of the DCH exhibited significantly longer active and shorter resting bouts than did LARS caribou, consistent with a moderate level of insect harassment. Responses of caribou to overflights were mild in late winter and, thus, overflights did not constitute a disturbance. Post-calving caribou responded to overflights by increasing daily activity, linear movements, incremental energy cost, and average daily metabolic rate. Energetic responses and movements were significantly related to the loudest overflight of the day. In the insect season, activity levels increased significantly in response to overflights but with no corresponding increase in linear movements or energetics. My recommendations are to prohibit aircraft overflights of caribou during calving and post-calving periods and during key feeding times in insect harassment seasons. Research indicates the possibility of more severe effects in nutritionally stressed animals.
    • Ecological effects of invasive European bird cherry (Prunus padus) on salmonid food webs in Anchorage, Alaska streams

      Roon, David A.; Wipfli, Mark; Prakash, Anupma; Wurtz, Tricia (2011-08)
      Invasive species are a concern worldwide as they can displace native species, reduce biodiversity, and disrupt ecological processes. European bird cherry (Prunus padus) (EBC) is an invasive ornamental tree that is rapidly spreading and possibly displacing native trees along streams in parts of urban Alaska. The objectives of this study were to: 1) map the current distribution of EBC along two Anchorage streams, Campbell and Chester creeks, and 2) determine the effects of EBC on selected ecological processes linked to stream salmon food webs. Data from the 2009 and 2010 field seasons showed: EBC was widely distributed along Campbell and Chester creeks; EBC leaf litter in streams broke down rapidly and supported similar shredder communities to native tree species; and EBC foliage supported significantly less terrestrial invertebrate biomass relative to native deciduous tree species, and contributed significantly less terrestrial invertebrate biomass to streams compared to mixed native vegetation, but riparian EBC did not appear to affect the amount of terrestrial invertebrate prey ingested by juvenile coho salmon (Oncorhynchus kisutch). Although ecological processes did not seem to be dramatically affected by EBC presence, lowered prey abundance as measured in this study may have long-term consequences for stream-rearing fishes as EBC continues to spread over time.
    • Ecological factors influencing fish distribution in a large subarctic lake system

      Plumb, Miranda Paige (2006-05)
      The coastal climate and frequent wind storms in southwest Alaska create an atypical thermal environment (non-stratified in summer) in the remote Ugashik lakes. This study documents the distribution of lake trout 'Salvelinus namaycush, ' arctic char 'S. alpinus', Dolly Varden 'S. malma, ' arctic grayling 'Thymallus arcticus, ' round whitefish 'Prosopium cylindraceum, ' and pygmy whitefish 'P. coulterii' relative to depth, substrate particle size, food habits, length, and age in the absence of strong thermal structure. Sample sites were randomly chosen within sampling strata and gill nets were set at each site. Lake trout and round whitefish were most abundant and had the oldest individuals in the catch. In more typical thermally stratified lake systems lake trout and Arctic char usually move to colder, deeper water in summer. In the Ugashik lakes, however, both species were abundant in shallow water all summer. Prior to this study pygmy whitefish were undocumented in this system. The fish examined in the Ugashik lakes were opportunistic feeders, consuming organisms such as isopods and amphipods. Fish in the Ugashik lakes were found in locations different from what one would expect from predominant literature. Fisheries managers may need to take this into account in their fisheries management.
    • Ecology of Prince of Wales spruce grouse

      Nelson, Aleya R. (2010-12)
      Recently, spruce grouse on Prince of Wales Island (POW) in southeast Alaska have been proposed as a separate subspecies. Furthermore, life-history of spruce grouse on POW, which is temperate coastal rainforest, varies sufficiently from birds in mainland areas, mostly boreal forest, to warrant specific management. Therefore, I examined the ecology of spruce grouse on POW to determine how timber harvest influences their survival and habitat selection and ultimately to provide recommendations for their conservation. During 2007-2009, we found that the greatest variation in survival probability was attributed to breeding status. The annual survival of non-breeding birds was 0.72±0.082 (S±) while for breeding birds it was 0.08±0.099. Logging did not adequately predict survival, with no differences among habitats. Conversely, I found differences in selection among habitats. At the watershed scale, spruce grouse preferred unharvested forest. At both watershed and homerange scales, spruce grouse avoided edges and preferred roads. Road-related mortality was the largest known source of death. POW spruce grouse and mainland subspecies exhibit sufficiently different survival rates and habitat preference to warrant specific management. We recommend limited road closures during periods when POW spruce grouse are most vulnerable due to the high rates of mortality associated with this preferred habitat.
    • Ecology of slimy sculpin (Cottus cognatus) in the Chena River, Alaska

      Sonnichsen, Sandra K. (1981-12)
      The purpose of this study was to gather information on the ecology of slimy sculpin (Cottus cognatus) in the upper Chena River. Three major topics were examined: age and growth, food habits, and habitat preferences. Age of fish was analyzed by length frequency and otoliths. Chena River sculpin were slow growing, reaching a maximum length of 86 mm in 7 years. Stomach contents were examined to determine contribution of different prey to the diet. Chironomids and large mayflies were most important in the diet; electivity indices indicated positive selection for them. Habitat preferences were examined by capturing fish, and measuring habitat variables at the point of capture. These data were analyzed using multiple regressions on principal components. No significant correlation was found between number of sculpin caught and habitat variables of depth, velocity, and substrate type.
    • 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.