For Marine Biology, see the Marine Sciences collection.

Recent Submissions

  • Effects of calcium magnesium acetate on small ponds in interior Alaska

    Rea, Caryn L. (1986-09)
    Deicing winter roads with chlorides has been common practice in northern areas. Corrosion of vehicles, structures, and pavements has resulted in damage, and roadside vegetation and public water supplies have been severely impacted by heavy salt usage. Calcium magnesium acetate (CMA) was identified as a promising alternative to chloride salts. This research focused on the effects on planktonic algae and bacteria in small ponds, to help assess the environmental acceptability of CMA in Alaska. The most serious consequence resulting from CMA was a dissolved oxygen concentration decrease, partly attributable to increased bacteria populations utilizing oxygen during degradation of acetate. Algal biomass recovered toward the end of the summer indicating that the algae may be utilizing some of the carbon dioxide being released by the bacteria. Rapid turnover times of acetate by bacteria in the fall and continued low dissolved oxygen indicated that some of the acetate was being recycled.
  • Seasonal changes in body mass and composition of northern red-backed voles (Clethrionomys rutilus) in interior Alaska

    Zuercher, Gerald Lawrence (1995-12)
    Northern red-backed voles (Clethrionomys rutilus) undergo a pronounced annual cycle in body mass: highest in summer, lowest in winter. I trapped voles throughout 1994 to determine how body composition and relative size of body components contributed to this cycle. Seasonal changes in body mass were primarily due to changes in body water and lean dry matter. Total body fat was low throughout the year, peaking in spring and early summer. Relative ash content was lowest in early summer. Most body components declined in dry mass and percent water during autumn, with skeletomuscular components contributing most to loss of body mass. Most body components declined in proportion to declines in body mass, but a few components declined proportionally greater than or less than body mass. Total Body Electrical Conductivity (TOBEC) of live voles explained 94% of the variation in lean mass and body water, but accuracy of fat estimates was poor.
  • Effects of military overflights on habitat use and selection by female Dall's sheep, Yukon-Tanana uplands, Alaska

    Wendling, Bradley R. (2008-12)
    "My objective was to assess the potential effects of military overflights on home range size, movement rates, habitat use, and habitat selection of female Dall's sheep (Ovis dalli) during 2-week sequential periods, April-July, 1999-2002. I examined sheep in 2 study areas overlain with designated military training airspace within the Yukon-Tanana uplands, Alaska. I examined the effects of study area, year, and sequential time period on: 1) mean home range size, 2) mean minimum hourly distance traveled by sheep, and 3) mean use and selection ratios for the habitat variables of elevation, slope, terrain ruggedness, aspect, and landcover class. Mean number of daily military sorties within sequential periods was used as a covariate in all analyses. I assessed habitat selection at 3 successive spatial scales defined as: 1) the regional geographical range of female Dall's sheep in the Yukon-Tanana uplands, 2) study areas (defined as the distribution of sheep within a localized area), and 3) selection within individual 2-week home ranges. Sheep home range size, movement rates, habitat use and selection ratios at the scale of region and study area differed between study areas, among years within study areas, and among sequential time periods within years within study areas, but did not vary in relation to military overflight intensity. I detected an effect of sorties on selection ratios at the home range scale; however, sorties explained <4% of the residual variation in these variables. I conclude that increases in intensity of military training operations during Major Flying Exercises (MFE's) over the Yukon-Tanana uplands were a relatively insignificant source of variance in activity and habitat use compared to the effects of seasons, years, and study areas"--Leaf iii
  • Human impacts on brown bears at Pack Creek, Admiralty Island, Alaska

    Warner, Susan H. (1987-05)
    Human disturbance of brown bears (Ursus arctos) was studied at Pack Creek on Admiralty Island in Southeast Alaska during 1983 and 1984. The Pack Creek watershed is closed to bear hunting. Use of the area by bear-watchers is increasing. Instantaneous scan sampling was used to observe bears at a control area with negligible human activity and at the popular Pack Creek area. Six bears were radio-collared to assess movements away from Pack Creek. Bears were crepuscular in the two areas. Individuals that were highly tolerant of visitors used the Pack Creek area during the mid-day period of high visitor use more than other bears. Over 80% of the observations of Pack Creek bears were of females, suggesting that visitor use may differentially affect sexes. Food-conditioned bears showed boldness that could cause undesirable incidents. Except for occasional sallies, Pack Creek females remained within the watershed. Males frequented several watersheds.
  • The morphology and chemistry of two willow species in relation to moose winter browsing

    Suter, Suzanne M. (1992-12)
    This study examines the interaction between moose (Alces alces gigas) and winter dormant willows (Salix alaxensis and Salix pulchra) in Alaska, emphasizing the impact of moose browsing on the forage produced by willow. In a two year field study, plant responses were examined with clipping treatments designed to simulate browsing by moose. The plant responses examined included biomass production, plant architecture, and concentration of plant tannins. Forage selection by moose in the study area is also addressed. Results suggest that a plant response of increased growth, decreased chemical defense, and redistribution of new biomass may explain the pattern of repeated browsing of plants by moose. The responses of clipped plants indicate that moose improve the quality of their willow hosts by browsing and repeated browsing negatively affects carbon reserves of willows. Among and within plant variation in tannin content was also examined among 5. alaxensis trees. Observations are related to within and among tree measurements of growth rate.
  • Marbled murrelet distribution and abundance in relation to the marine environment

    Speckman, Suzann G. (1996-08)
    I examined the effects of the physical variables season, time of day, tide stage, sea surface temperature, and weather and the biological variables phenology and productivity on Marbled Murrelet (Brachyramphus marmoratus) abundance and distribution in Auke Bay and Fritz Cove, Alaska. I surveyed murrelets daily from the shore and a small boat from May through August, 1992 and 1993, and evaluated the impacts of murrelet abundance patterns on a monitoring strategy. I also examined the breeding biology, behavior, and social structure of Marbled Murrelets in an effort to gauge the effects of declining populations on their daily activities, such as foraging and courtship behavior of adults, and foraging strategies of juveniles. I found significant effects of year, season, time of day, and tide stage on Marbled Murrelet numbers at sea that have important implications for designing monitoring surveys to assess changes in Marbled Murrelet populations in Alaska and elsewhere.
  • Distribution, abundance, and quality of forage within the summer range of the central Arctic caribou herd

    Smith, Michael D. (1996-12)
    Distribution, abundance, and quality of summer forage available to caribou (Rangifer tarandus granti) of the Central Arctic Herd were determined in July and August, 1989 -1990. Plant cover, an index of available biomass, was measured at three sites within 50 km of the arctic coast. In general, plant cover increased with distance from the coast. Cover of forbs and evergreen shrubs was higher at inland sites (P < 0.001), whereas cover of willows (Salix spp.) was highest at the coastal site (P < 0.001). Higher plant cover inland is largely attributable to a greater proportion of drier habitats. Differences in forage quality among sites, however, were small and inconsistent. I conclude that by feeding inland during insect-free periods, caribou realize a net energy benefit, because of higher plant biomass, higher proportion of drier habitat, and greater species diversity than coastal areas.
  • Seasonal distribution and winter habitat use by Sitka black-tailed deer in the Prince William Sound region, Alaska

    Shishido, Neil (1986-05)
    Intensity of winter use of a variety of forest stands by deer (Odocoileus hemionus sitkensis) was measured. Information on vegetation, timber type, and topography was collected to find relationships between deer use and habitat variables. Seasonal use of forest stands by deer is best described in terms of: basal area of trees, amount of deer forage (Vaccinium spp. and Coptis aspleniifolia)r deviation in crown closure, and timber volume. Information from radio-collared deer indicated high use of forest habitat, particularly during winter. Alpine areas received more use than any other habitat during summer. South-facing slopes were used more often than other aspects across all seasons. Average winter home range size was 160 ha, significantly smaller than the spring average (282 ha). Most radio-collared deer made seasonal elevational movements within a single drainage. Retention of high timber volume, old growth forest is recommended to maintain preferred deer habitat in Prince William Sound.
  • Walrus feeding: a re-examination

    Sheffield, Gay Glover (1997-08)
    A new approach for analyzing walrus (Odobenus rosmarus) diet was examined. Controlled gastric digestion experiments determined the relative rates at which different kinds of food items became unidentifiable. The ability to identify prey items varied within and among prey types. The laboratory experiments provided a new basis for examining diet data by characterizing the condition of stomach samples based on the rates at which different prey types were digested. Stomach content data acquired during 1952-1991 from 798 Pacific walruses were compiled, and interpretations about feeding habits were re-examined. Walruses regularly consumed a wider assortment of benthic prey than was previously thought. The diet of the Pacific walrus varied seasonally and regionally. Males and females consumed essentially the same food items when in the same location.
  • Effects of weather and parasitic insects on summer ecology of caribou of the Delta herd

    Mörschel, Frank Matthias (1996-08)
    The roles of weather and parasitic insects in caribou (Rangifer tarandus) ecology were investigated to determine their influence on population dynamics of the Delta Herd. Data on weather, insect abundance, and caribou behavior were collected during two summers. Mosquito season started 21 and 11 June and oestrid fly season 11 July and 21 June in 1994 and 1995, respectively. Mosquito activity was limited by windspeed at temperatures >7°C. Oestrid fly presence was influenced mainly by temperature. Presence of insects and temperature positively influenced, and windspeed negatively influenced rate of activity changes of caribou. Feeding decreased and standing increased with insect presence and temperature. Increasing temperature affected activity budgets even in the absence of insects by decreasing feeding activities. Weather, especially temperature, and parasitic insects, especially oestrid flies, affected caribou mainly by limiting forage intake and increasing energy expenditure. Estimated activity budgets in summers of 1976-1995 indicated possible limiting effects of temperature on population dynamics.
  • Habitat selection and reproductive ecology among Townsend's warblers (Dendroica townsendi) in southcentral Alaska

    Matsuoka, Steven Mark (1996-05)
    I investigated habitat selection and reproductive ecology among Townsend's Warblers (Dendroica townsendi) in mature mixed forests near Anchorage, Alaska. I examined selection of territories, nest sites, and foraging sites to identify habitat features associated with each resource. Male pairing and nest survival were monitored to identify factors influencing reproductive success. Females were highly selective for large white spruce (Picea glauca) as nest sites. Foraging behavior varied temporally and was specialized toward medium white spruce early in the breeding season but subsequently generalized across substrates. Territories were heterogeneous in habitat and were characterized by habitat features selected for nesting and foraging, suggesting specific demands for resources influenced choice of territories. Pairing success (98%) and nest success (51%) were generally higher than that of migratory songbirds breeding in forest fragments. Nest predation and blow fly (Protocalliphora) parasitism, factors constraining reproductive output, varied with microhabitat, suggesting that habitat selection may mitigate their effects.
  • Climate and caribou: effects of summer weather on the Chisana caribou herd

    Lenart, Elizabeth A. (1997-08)
    In 1989, the Chisana caribou (Rangifer tarandus) herd in the northern Wrangell Mountains, Alaska declined substantially in population size and productivity. Summers were significantly warmer and slightly drier during years the herd was declining (1989-1995) compared with years when the herd was stable or increasing (1981-1988). We increased air temperature and decreased precipitation with a plastic tent, decreased light intensity with a shade cloth, and increased precipitation by adding water to determine climatic effects on nutrient content and biomass of caribou forage during summer in 1994 and 1995 in the subarctic tundra. We determined that short-term variations in climate affected nutrient quality, particularly nitrogen content, in above-ground biomass of caribou forage. The warmer, drier summers (1989-1995) may have affected the Chisana population adversely by increasing insect harassment and decreasing nitrogen content in their forage.
  • Phylogeographic variation and the island syndrome in holarctic tundra voles (Microtus oeconomus)

    Lance, Ellen Weintraub; Cook, Joseph A.; Klein, David R. (1995-12)
    Phylogeographic patterns of genetic and morphologic variation were explored among six subspecies of the Holarctic tundra vole (Microtus oeconomus). but focused on those populations occurring in southcoastal Alaska. Allozyme electrophoresis and karyotyping revealed that, although levels of intraspecific variation were low compared to other species of Microtus. allozymic divergence was concordant with regional glacial history. Tundra voles from interior Alaska became established prior to the last glacial retreat. However, populations from southcoastal Alaska were founded more recently. Tundra voles from Montague Island, an endemic subspecies, exhibited features of the island syndrome (i. e., gigantism, older age structure). Factors potentially responsible for insular gigantism were assessed. The findings of this study fail to support the hypothesis that the island syndrome is a direct result of interspecific competition. Other density-dependent factors, such as predation, may be responsible for body size and demographic changes in these insular rodents.
  • Diet and nestling growth of red-legged and black-legged kittiwakes: an interspecies cross-fostering experiment

    Lance, Brian K. (1996-05)
    I conducted an interspecific cross-fostering experiment to investigate how diet composition and feeding rates affected nestling survival, growth, and gastrointestinal development of Red-legged and Black-legged kittiwakes on St. George Island, Alaska. Red-legged Kittiwakes (Rissa brevirostris) fed nestlings primarily lanternfish (Myctophidae), a high-lipid diet, whereas Black-legged Kittiwakes (R. tridactyla) fed nestlings mostly walleye pollock (Theragra chalcogramma), a low-lipid diet. Nestling meal size was similar for the two species, but Red-legged Kittiwakes fed nestlings at about half the rate of Black-legged Kittiwakes. Interspecific differences in nestling growth were explained by differences in adult body mass. Survival rates and lean body mass did not differ between fostered nestlings and conspecific controls. Nestlings raised by Red-legged Kittiwakes had 50% larger fat reserves than those raised by Black-legged Kittiwakes. Thus growth rates of lean tissue were genetically constrained, while rates of fat deposition were determined by diet Interspecific differences in gastrointestinal anatomy were partly genetic and partly dietary in origin.
  • Life-history consequences of maternal condition in Alaskan moose

    Keech, Mark A. (1999-05)
    We studied characteristics of life-history of Alaskan moose (Alces alces gigas) including the effects of maternal condition of adult females on survival and physical condition of young during their first year-of-life. We also examined the relation between maternal condition and reproductive parameters of individual adult moose. We found that females in better physical condition, as indexed by rump-fat thickness, had higher rates of pregnancy, gave birth to more twins, and produced young with higher birth masses than did females with less rump fat. Expected time-to-death for individual young increased as birth mass increased and decreased with increasing birth date and litter size. Our results indicated maternal condition influenced subsequent variables associated with birth, which ultimately influenced future survival of offspring. Timing of parturition also occurred earlier for individual females with greater rump-fat thickness. That outcome suggested that timing of parturition was the result of environmental factors acting on females prior to birth.
  • Angler effort, exploitation, and values on the upper Chena River, Alaska

    Holmes, Rolland A.; Jack, Stephen L.; Reynolds, James B. (1981-05)
    Methods of improving accuracy and efficiency of creel census estimates were tested during the summers of 1979 and 1980 on the grayling (Thymallus arcticus) fishery of the upper Chena River. Roving counts of fishermen accurately (within 10%) reflected angler use. Incomplete trip catch-per-unit-effort estimates obtained from a roving creel census were free from sampling bias. Stratification (weekends vs. weekdays) resulted in a twofold increase in precision of use estimates. A two-stage sampling design (time periods within days) improved efficiency of sampling. Motivations and values of interior Alaskan anglers were evaluated using survey questionnaires. Aspects of the fishing ex­perience not related to catching fish, such as companionship, out­door enjoyment, and relaxation, were primary motivations for most (94%) anglers. The catch-related motivations were also important to a large portion (63%) of anglers. The upper Chena River fishery had many attributes which, when taken together, provided satisfactory fishing experiences to a wide range of angler types.
  • Summer habitat relationships and foraging ecology of the Delta bison herd

    Berger, Maria (1996-05)
    Investigations of habitat use, diet composition and diet selection of introduced plains bison (Bison bison bison) in interior Alaska in summer were conducted during 1989 through 1991. Bison used early- and mid-successional plant communities on the floodplain of the Delta River and wetlands above the floodplain. Grasses predominated in summer diets of bison, but substantial amounts of willow (Saiix) were included. Other shrubs were used much less than available, as were sedges. The role of sedges in bison diets may be changing as bison increasingly have exploited sedge-dominated wetland habitats. Experimental studies of the effects of bison grazing on forage productivity, forage quality and plant species composition were conducted in the mid-successional graminoid meadow, the traditional summer range of Delta bison. Bison grazing had no effect on productivity but did increase nitrogen concentration of graminoids. Changes in plant species composition occurred in response to protection from grazing for 9 years.
  • Habitat use by parturient and nonparturient caribou of the Mentasta caribou herd

    Barten, Neil L. (1998-08)
    I compared habitat use and diet characteristics among preparturient female caribou (Rangifer tarandus), and between parturient and nonparturient caribou during and after parturition, in the Mentasta Caribou Herd, Alaska, to explain movements by parturient females just prior to giving birth. I monitored 39 radio-collared females in 1994 and 40 animals in 1995. I estimated forage biomass, collected forage for determination of nitrogen and in-vitro dry matter digestibility (IVDMD), and collected fecal pellets to calculate indices of diet composition and diet quality at sites used by caribou. I also recorded sightings of predators throughout the study area. During peak parturition, females with young used habitat with fewer predator sightings, a lower abundance of forage species, but with nearly equal forage quality as that used by females without young. I hypothesized that parturient females used birth sites that lowered the risk of predation, and did so at little cost nutritionally.
  • Seasonal drivers of amplitude patterns in a population of red-backed voles (Clethrionomys rutilus)

    Swanson, Sarah; Kielland, Knut; Crimmins, Shawn; Wagner, Diane; Flamme, Melanie (2023-08)
    Northern red-backed voles (Clethrionomys rutilus) are an important species in the Interior Alaska boreal forest ecosystem, both as important herbivores and as a key food source for many mammalian and avian predators. However, they exhibit dramatic inter- and intra-annual population fluctuations, for which causes are not entirely known. Winter mortality is often very high and altered weather conditions due to climate change, such as rain on snow or delayed snowfall in autumn, may increase stress during an already difficult season. These considerations prompted this investigation into overwinter survival of northern red-backed voles in Denali National Park and Preserve, with the goal of examining a time series of population densities and assessing how weather variables influenced patterns of mortality. Using a 30-year record of mark-recapture data, I applied spatially-explicit methods to calculate density estimates for autumn and early summer trapping sessions. I also assessed cyclic behavior and used post-hoc linear modeling to examine patterns in amplitude and period of population fluctuations. I found that this microtine population appears to be cycling on a 2-4 year period, with some differentiation among sampling sites. Models of autumn amplitudes suggested a linkage between white spruce (Picea glauca) seed mast, either an important source of food during winter seasons, or as a coincidental product of the underlying multi-annual environmental triggers that promote high seed fall. I also found a negative effect of combined late snowfall and cold temperatures, a scenario that may become more prominent under future climate changes. Lastly, my models of early summer density showed an apparent negative density dependence, in which high population densities in autumn were followed by low densities the following spring. Continued monitoring of voles, alongside more thorough assessments of snow conditions, habitat, diet, and predator status would assist further attempts to cast light upon the complex population dynamics of this species and their many predators.
  • Adapting density surface models for complex survey areas: application to humpback whale (Megaptera novaeangliae) abundance and distribution estimation in Southeast Alaska

    Schiffmiller, Abigail; Breed, Greg A.; Zerbini, Alexandre; Doak, Pat (2023-08)
    Population abundance and distribution estimates are foundational to understanding and managing populations. Increasing accuracy and resolution of such estimates increases their utility for researchers and managers. Line transect surveys analyzed using both traditional design-based distance sampling (dbDS) and spatially explicit density surface modeling (DSM) are used across systems and taxa to estimate abundance and distributions of populations. DSM has the advantages of being able to increase the resolution of density estimates and evaluate the correlation between density and environmental factors as well as accepting data from a wider variety of surveys. In this thesis I used a soap film smoother to apply DSM in a more complex habitat than it has previously been used for. I compared abundance and distribution estimates from dbDS and DSM, using line transect survey data of humpback whales (Megaptera novaeangliae) in southeast Alaska, to explore and evaluate the applicability of DSM in extremely complex habitats. I found that DSM estimated distribution at a more useful higher resolution than dbDS. Abundance estimates from dbDS were approximately 50% higher than for DSM, and while further comparisons are needed to clarify relative accuracy, the abundance estimates are reasonable compared with other sources. The results demonstrate that DSM is applicable in habitats with extremely complex boundaries.

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