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11370 results.

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Interactions between soil thermal and hydrological dynamics in the response of Alaska ecosystems to fire disturbance
Shuhua Yi, A. David McGuire, Jennifer Harden, Eric Kasischke, Kristen L. Manies, Larry Hinzman, Anna K. Liljedahl, J. Randerson, Heping Liu, Vladimir E. Romanovsky, Sergey S. Marchenko, Yongwon Kim
2009, Journal of Geophysical Research: Biogeosciences (114)
Soil temperature and moisture are important factors that control many ecosystem processes. However, interactions between soil thermal and hydrological processes are not adequately understood in cold regions, where the frozen soil, fire disturbance, and soil drainage play important roles in controlling interactions among these processes. These interactions were investigated with...
Estuarine Ecology of Juvenile Salmon in Western Alaska: a Review
Christian E. Zimmerman, Nicola Hillgruber
2009, Book chapter, American Fisheries Society Symposium
In the late 1990s and early 2000s, large declines in numbers of chum salmon Oncorhynchus keta and Chinook salmon O. tshawytscha returning to the Arctic-YukonKuskokwim (AYK) region (Alaska, USA) illuminated the need for an improved understanding of the variables controlling salmon abundance at all life stages. In addressing questions about...
Multi-segment earthquakes and tsunami potential of the Aleutian megathrust
I. Shennan, R. Bruhn, George Plafker
2009, Quaternary Science Reviews (28) 7-13
Large to great earthquakes and related tsunamis generated on the Aleutian megathrust produce major hazards for both the area of rupture and heavily populated coastlines around much of the Pacific Ocean. Here we use paleoseismic records preserved in coastal sediments to investigate whether segment boundaries control the largest ruptures or...
Evaluating the validity of using unverified indices of body condition
J.L. Schamber, Daniel Esler, Paul L. Flint
2009, Journal of Avian Biology (40) 49-56
Condition indices are commonly used in an attempt to link body condition of birds to ecological variables of interest, including demographic attributes such as survival and reproduction. Most indices are based on body mass adjusted for structural body size, calculated as simple ratios or residuals from regressions. However, condition indices...
Disentangling effects of growth and nutritional status on seabird stable isotope ratios
J. Sears, Scott A. Hatch, D. M. O’Brien
2009, Oecologia (159) 41-48
A growing number of studies suggest that an individual’s physiology affects its carbon and nitrogen stable isotope signatures, obscuring a signal often assumed to be only a reflection of diet and foraging location. We examined effects of growth and moderate food restriction on red blood cell (RBC) and feather δ15N...
Multi-offset GPR methods for hyporheic zone investigations
T.R. Brosten, J.H. Bradford, J. P. McNamara, M.N. Gooseff, J.P. Zarnetske, W.B. Bowden, M.E. Johnston
2009, Conference Paper, Near Surface Geophysics
Porosity of stream sediments has a direct effect on hyporheic exchange patterns and rates. Improved estimates of porosity heterogeneity will yield enhanced simulation of hyporheic exchange processes. Ground-penetrating radar (GPR) velocity measurements are strongly controlled by water content thus accurate measures of GPR velocity in saturated sediments provides estimates of...
Suspended sediment and carbonate transport in the Yukon River Basin, Alaska: Fluxes and potential future responses to climate change
Mark M. Dornblaser, Robert G. Striegl
2009, Water Resources Research (45)
Loads and yields of suspended sediment and carbonate were measured and modeled at three locations on the Yukon, Tanana, and Porcupine Rivers in Alaska during water years 2001–2005 (1 October 2000 to 30 September 2005). Annual export of suspended sediment and carbonate upstream from the Yukon Delta averaged 68 Mt...
Late Quaternary paleoclimate of western Alaska inferred from fossil chironomids and its relation to vegetation histories
Joshua Kurek, Les C. Cwynar, Thomas A. Ager, Mark B. Abbott, Mary E. Edwards
2009, Quaternary Science Reviews (28) 799-811
Fossil Chironomidae assemblages (with a few Chaoboridae and Ceratopogonidae) from Zagoskin and Burial Lakes in western Alaska provide quantitative reconstructions of mean July air temperatures for periods of the late-middle Wisconsin (~39,000-34,000 cal yr B.P.) to the present. Inferred temperatures are compared with previously analyzed pollen data from each site...
Relationships between hepatic trace element concentrations, reproductive status, and body condition of female greater scaup
Shannon S. Badzinski, Paul L. Flint, Kristen B. Gorman, Scott A. Petrie
2009, Environmental Pollution (157) 1886-1893
We collected female greater scaup (Aythya marila) on the Yukon–Kuskokwim Delta, Alaska during two breeding seasons to determine if concentrations of 18 trace elements in livers and eggs were elevated and if hepatic concentrations correlated with body condition or affected reproductive status. Fifty-six percent, 5%, and 42% of females, respectively,...
Observation and modeling of source effects in coda wave interferometry at Pavlof volcano
Matthew M. Haney, Wijik K. van, L.A. Preston, D.F. Aldridge
2009, The Leading Edge (28) 554-560
Sorting out source and path effects for seismic waves at volcanoes is critical for the proper interpretation of underlying volcanic processes. Source or path effects imply that seismic waves interact strongly with the volcanic subsurface, either through partial resonance in a conduit (Garces et al., 2000; Sturton and Neuberg, 2006)...
A distal earthquake cluster concurrent with the 2006 explosive eruption of Augustine Volcano, Alaska
M. A. Fisher, N.A. Ruppert, R.A. White, Frederic H. Wilson, D. Comer, R. W. Sliter, F. L. Wong
2009, Tectonophysics (469) 25-36
Clustered earthquakes located 25 km northeast of Augustine Volcano began about 6 months before and ceased soon after the volcano's 2006 explosive eruption. This distal seismicity formed a dense cluster less than 5 km across, in map view, and located in depth between 11 km and 16 km. This seismicity was contemporaneous with sharply increased...
Implications for the dynamic health of a glacier from comparison of conventional and reference-surface balances
W.D. Harrison, L.H. Cox, R. Hock, R.S. March, E.C. Pettit
2009, Annals of Glaciology (50) 25-30
Conventional and reference-surface mass-balance data from Gulkana and Wolverine Glaciers, Alaska, USA, are used to address the questions of how rapidly these glaciers are adjusting (or 'responding') to climate, whether their responses are stable, and whether the glaciers are likely to survive in today's climate. Instability means that a glacier...
Utilizing chromophoric dissolved organic matter measurements to derive export and reactivity of dissolved organic carbon exported to the Arctic Ocean: A case study of the Yukon River, Alaska
R.G.M. Spencer, G. R. Aiken, K.D. Butler, M.M. Dornblaser, Robert G. Striegl, P.J. Hernes
2009, Geophysical Research Letters (36)
[1] The quality and quantity of dissolved organic matter (DOM) exported by Arctic rivers is known to vary with hydrology and this exported material plays a fundamental role in the biogeochemical cycling of carbon at high latitudes. We highlight the potential of optical measurements to examine DOM...
Rupture imaging of the Mw 7.9 12 May 2008 Wenchuan earthquake from back projection of teleseismic P waves
Y. Xu, K.D. Koper, O. Sufri, L. Zhu, Alexander R. Hutko
2009, Geochemistry, Geophysics, Geosystems (10)
[1] The Mw 7.9 Wenchuan earthquake of 12 May 2008 was the most destructive Chinese earthquake since the 1976 Tangshan event. Tens of thousands of people were killed, hundreds of thousands were injured, and millions were left homeless. Here we infer the detailed rupture process of the Wenchuan earthquake by...
Petrology and geochronology of crustal xenoliths from the Bering Strait region: Linking deep and shallow processes in extending continental crust
V.V. Akinin, E. L. Miller, J. L. Wooden
2009, Special Paper of the Geological Society of America 39-68
Petrologic, geochemical, and metamorphic data on gneissic xenoliths derived from the middle and lower crust in the Neogene Bering Sea basalt province, coupled with U-Pb geochronology of their zircons using sensitive high-resolution ion microprobe-reverse geometry (SHRIMP-RG), yield a detailed comparison between the P-T-t and magmatic history of the lower crust...
Breeding-season sympatry facilitates genetic exchange among allopatric wintering populations of Northern Pintails in Japan and California
Paul L. Flint, Kiyoaki Ozaki, John M. Pearce, Brian Guzzetti, Hiroyoshi Higuchi, Joseph P. Fleskes, Tetsuo Shimada, Dirk V. Derksen
2009, Condor (111) 591-598
The global redistribution of pathogens, such as highly pathogenic avian influenza, has renewed interest in the connectivity of continental populations of birds. Populations of the Northern Pintail (Anas acuta) wintering in Japan and California are considered separate from a management perspective. We used data from band recoveries and population genetics...
Advancing landscape change research through the incorporation of Inupiaq knowledge
Wendy R. Eisner, Chris J. Cuomo, Kenneth M. Hinkel, Benjamin M. Jones, Ronald H. Brower Sr.
2009, Arctic (62) 429-442
  Indigenous knowledge is a valuable but under-used source of information relevant to landscape change research. We interviewed Iñupiat elders, hunters, and other knowledge-holders in the villages of Barrow and Atqasuk on the western Arctic Coastal Plain of northern Alaska to gain further insight into the processes governing the ubiquitous lakes...
Lesser scaup breeding probability and female survival on the yukon flats, Alaska
K. H. Martin, M. S. Lindberg, Joel A. Schmutz, M.R. Bertram
2009, Journal of Wildlife Management (73) 914-923
Information on the ecology of waterfowl breeding in the boreal forest is lacking, despite the boreal region's importance to continental waterfowl populations and to duck species that are currently declining, such as lesser scaup (Aythya affinis). We estimated breeding probability and breeding season survival of female lesser scaup on the...
Strategies for nest-site selection by king eiders
R.L. Bentzen, A.N. Powell, R.S. Suydam
2009, Journal of Wildlife Management (73) 932-938
Nest site selection is a critical component of reproduction and has presumably evolved in relation to predation, local resources, and microclimate. We investigated nest-site choice by king eiders (Somateria spectabilis) on the coastal plain of northern Alaska, USA, 2003-2005. We hypothesized that nest-site selection is driven by predator avoidance and...
Numerical study of tsunami generated by multiple submarine slope failures in Resurrection Bay, Alaska, during the MW 9.2 1964 earthquake
E. Suleimani, R. Hansen, Peter J. Haeussler
2009, Conference Paper, Pure and Applied Geophysics
We use a viscous slide model of Jiang and LeBlond (1994) coupled with nonlinear shallow water equations to study tsunami waves in Resurrection Bay, in south-central Alaska. The town of Seward, located at the head of Resurrection Bay, was hit hard by both tectonic and local landslide-generated tsunami waves during...
Exhumation along the Fairweather fault, southeastern Alaska, based on low-temperature thermochronometry
R.J. McAleer, J.A. Spotila, E. Enkelmann, A.L. Berger
2009, Tectonics (28)
The southern Alaskan syntaxis marks the spectacular junction between the >1000-km-long Pacific-North America transform margin and the Chugach-St. Elias belt, where subduction and terrane accretion drive rapid convergent deformation and rock uplift. New low-temperature thermochronometry reveals that intense orogenic deformation is not restricted to one side of the syntaxis but...
Interactive effects of fire, soil climate, and moss on CO2 fluxes in black spruce ecosystems of interior Alaska
J. A. O'Donnell, M.R. Turetsky, J.W. Harden, K.L. Manies, L.E. Pruett, G. Shetler, J. C. Neff
2009, Ecosystems (12) 57-72
Fire is an important control on the carbon (C) balance of the boreal forest region. Here, we present findings from two complementary studies that examine how fire modifies soil organic matter properties, and how these modifications influence rates of decomposition and C exchange in black spruce (Picea mariana) ecosystems of...
Cobble cam: Grain-size measurements of sand to boulder from digital photographs and autocorrelation analyses
J.A. Warrick, D. M. Rubin, P. Ruggiero, J.N. Harney, A.E. Draut, D. Buscombe
2009, Earth Surface Processes and Landforms (34) 1811-1821
A new application of the autocorrelation grain size analysis technique for mixed to coarse sediment settings has been investigated. Photographs of sand- to boulder-sized sediment along the Elwha River delta beach were taken from approximately 1??2 m above the ground surface, and detailed grain size measurements were made from 32...
Red-throated loons (Gavia stellata) breeding in Alaska, USA, are exposed to PCBs while on their Asian wintering grounds
Joel A. Schmutz, K.A. Trust, A.C. Matz
2009, Environmental Pollution (157) 2386-2393
Red-throated loons (Gavia stellata) breeding in Alaska declined 53% during 1977-1993. We compare concentrations of environmental contaminants in red-throated loons among four nesting areas in Alaska and discuss potential ramifications of exposure on reproductive success and population trends. Eggs from the four areas had similar total polychlorinated biphenyl (PCB) concentrations,...