• Multi-sensor techniques for the measurement of post eruptive volcanic deformation and depositional features

      McAlpin, David B.; Meyer, Franz J.; Begét, James; Webley, Peter W.; Dehn, Jonathan (2019-08)
      Remote sensing of volcanic activity is an increasingly important tool for scientific investigation, hazard mitigation, and geophysical analysis. These studies were conducted to determine how combining remote sensing data in a multi-sensor analysis can improve our understanding of volcanic activity, depositional behavior, and the evolutionary history of past eruptive episodes. In a series of three studies, (1) optical photogrammetry and synthetic aperture radar are combined to determine volumes of lahars and lava dome growth at Redoubt Volcano, Alaska; (2) applied data from multiple synthetic aperture radar platforms are combined to model long-term deposition of pyroclastic flow deposits, including past deposits underlying current, observable pyroclastic flow deposits at Augustine Volcano, Alaska; and finally (3) combined, low-spatial-resolution thermal data from Advanced Very High Resolution Radiometer sensors are combined with high resolution digital elevation models derived from the microwave TanDEM-X mission, to increase the accuracy of eruption profiles and effusion rates at Tolbachik Volcano on the Kamchatka Peninsula, Russian Far East. As a result of this study, the very diverse capabilities of multiple remote sensing instruments were combined to improve the understanding of volcanic processes at three separate locations with recent eruptive activity, and to develop new methods of measurement and estimation by merging the capabilities of optical, thermal, and microwave observations. With the multi-sensor frameworks developed in this study now in place, future efforts should focus on increasing the diversity of sensor types in joint analyses, with the objective of obtaining better solutions to geophysical questions.
    • Phylogeography and population genetics of a Beringian endemic: Dallia (Esociformes: Teleostei)

      Campbell, Matthew A.; López, J. Andrés; Takebayashi, Naoki; Olson, Matthew (2011-08)
      In this thesis I examine the population genetics of an endemic Beringian freshwater fish genus, Dallia (blackfish). The current distribution of blackfish was heavily influenced by paleoclimatic instability during the Pleistocene. Beringian paleoclimatic changes during the Pleistocene included the fluctuating growth and decline of glaciers and an overall decrease in temperature and increased aridity in areas not adjacent to the Bering Sea. Pleistocene glacial advances resulted in the cyclical emergence of the Bering land bridge. The effects of paleoclimatic instability on blackfish distribution and abundance can be inferred through the distribution of genetic variation across the Beringian landscape. I address three basic questions: 1: Are separate populations of blackfish taxonomically distinct entities? I found that while there is clear genetic structuring and isolation, there is insufficient information to make a strong statement in this regard. 2: Did blackfish survive Pleistocene glaciations within multiple Beringian refugia? My results indicate that blackfish persisted in at least four broad geographic areas. 3: How did the Bering land bridge influence intercontinental aquatic interchange? My evidence points to close genetic relationships and potentially high exchange of blackfish across the Bering land bridge, which supports the Bering land bridge as conduit for freshwater aquatic migration.
    • Remote sensing and GIS analysis of the spatial and morphological changes of thermokarst lakes: Kolyma lowlands, northeast Siberia

      Tillapaugh, Meghan L. (2011-05)
      Thermokarst lakes develop when changes in the permafrost thermal regime cause degradation leading to surface subsidence and ponding. The degree of thermokarst development depends upon permafrost characteristics, topography, and geology. Changing thermokarst lake dynamics affect arctic ecosystems, hydrological patterns, albedo, and the carbon cycle through the mobilization of organic matter in the permafrost. This study used remote sensing and GIS techniques to relate lake dynamics in the Kolyma Lowlands, Siberia, to geology, elevation, geomorphological features, hydrology, and air temperature. Highest limnicity and largest lake sizes were found in regions with low elevation, limited alluvial processes, high ground-ice content, and lithologies with small particle sizes. New lake development and erosion occurred as well. One subregion studied showed lake area increases (Cherskii: +7.6%) while another showed a decrease (Duvanny Yar: -5.2%). Differences are attributed to variations in elevation and fluvial influences. A major cause of drainage was river tapping of lakes. Lake coalescence, flooding during river water level high stands, and lakeshore erosion were the main causes of lake expansion. The Kolyma Lowland soils have high ice and organic matter contents as well making the monitoring of thermokarst lake dynamics important as large amounts of freshwater and carbon could potentially be released.
    • Reproductive ecology and morphometric subspecies comparisons of Dunlin (Calidris alpina), an arctic shorebird

      Gates, Heather River; Powell, Abby N.; Hunter, Christine M.; Lanctot, Richard B. (2011-12)
      The Arctic region provides globally important breeding and migratory habitat for abundant wildlife populations including migratory shorebirds. Due to their remote breeding locations, basic information on breeding ecology, annual productivity, and factors that regulate their populations are poorly studied. Wildlife biologists managing migratory bird populations require detailed information on avian breeding biology, in addition to information on migration ecology including connectivity of migratory stopover and wintering locations. To address information gaps in fecundity, I conducted an experimental study investigating the renesting ecology of Dunlin (Calidris alpina arcticola) by removing clutches at two stages of incubation and by following adults marked with radio transmitters to their replacement clutch. In contrast to predictions for arctic-breeding species, Dunlin had high (82-95%) rates of clutch replacement during early incubation and moderate (35-50%) rates during late incubation. Female body condition and date of clutch loss were important variables explaining propensity for females to replace a clutch; larger females that lost their nest early in the season were more likely to renest than smaller females who lost their nest later in the season. To delineate Dunlin subspecies in areas where they overlap, I used morphological and molecular approaches to determine sex and subspecies of five subspecies of Dunlin breeding in Alaska and eastern Russia. This analysis yielded discriminant function models to correctly classify unknown individuals to sex (79-98%) and subspecies (7385%) via morphometric measures. Correct classification of mixed assemblages of subspecies improved when sex, determined though molecular techniques, was known. The equations I derived using discriminant function models can be used to identify the sex and subspecies of unknown Dunlin individuals for studies investigating breeding and migration ecology.