Publications
USGS research activities relevant to Alaska have yielded more than 9400 historical publications. This page features some of the most recent newsworthy research findings.
Filter Total Items: 3104
Recent ecological divergence despite migration in sockeye salmon (Oncorhynchus nerka) Recent ecological divergence despite migration in sockeye salmon (Oncorhynchus nerka)
Ecological divergence may result when populations experience different selection regimes, but there is considerable discussion about the role of migration at the beginning stages of divergence before reproductive isolating mechanisms have evolved. However, detection of past migration is difficult in current populations and tools to differentiate genetic similarities due to migration...
Authors
Scott A. Pavey, Jennifer L. Nielsen, Troy R. Hamon
Survival and breeding of polar bears in the southern Beaufort Sea in relation to sea ice Survival and breeding of polar bears in the southern Beaufort Sea in relation to sea ice
1. Observed and predicted declines in Arctic sea ice have raised concerns about marine mammals. In May 2008, the US Fish and Wildlife Service listed polar bears (Ursus maritimus) - one of the most ice-dependent marine mammals - as threatened under the US Endangered Species Act. 2. We evaluated the effects of sea ice conditions on vital rates (survival and breeding probabilities) for...
Authors
E.V. Regehr, C.M. Hunter, H. Caswell, Steven C. Amstrup, I. Stirling
Intercontinental reassortment and genomic variation of low pathogenic avian influenza viruses isolated from northern pintails (Anas acuta) in Alaska: examining the evidence through space and time Intercontinental reassortment and genomic variation of low pathogenic avian influenza viruses isolated from northern pintails (Anas acuta) in Alaska: examining the evidence through space and time
Migration and population genetic data for northern pintails (Anas acuta) and phylogenetic analysis of low pathogenic avian influenza (LPAI) viruses from this host in Alaska suggest that northern pintails are involved in ongoing intercontinental transmission of avian influenza. Here, we further refine this conclusion through phylogenetic analyses which demonstrate that detection of...
Authors
Andrew M. Ramey, John M. Pearce, Paul L. Flint, S. Ip, Dirk V. Derksen, J. Christian Franson, Michael J. Petrula, Bradley D. Scotton, Kristine M. Sowl, Michael L. Wege, Kimberly A. Trust
Cytochrome P4501A biomarker indication of oil exposure in harlequin ducks up to 20 years after the Exxon Valdez oil spill Cytochrome P4501A biomarker indication of oil exposure in harlequin ducks up to 20 years after the Exxon Valdez oil spill
Hydrocarbon-inducible cytochrome P4501A (CYP1A) expression was measured, as ethoxyresorufin-O-deethylase (EROD) activity, in livers of wintering harlequin ducks (Histrionicus histrionicus) captured in areas of Prince William Sound, Alaska, USA, oiled by the 1989 Exxon Valdez spill and in birds from nearby unoiled areas, during 2005 to 2009 (up to 20 years following the spill). The...
Authors
Daniel Esler, Kimberly A. Trust, Brenda E. Ballachey, Samuel A. Iverson, Tyler L. Lewis, Daniel Rizzolo, Daniel M. Mulcahy, A. Keith Miles, Bruce R. Woodin, John J. Stegeman, John D. Henderson, Barry W. Wilson
Population dynamics of long-tailed ducks breeding on the Yukon-Kuskokwim Delta, Alaska Population dynamics of long-tailed ducks breeding on the Yukon-Kuskokwim Delta, Alaska
Population estimates for long-tailed ducks in North America have declined by nearly 50% over the past 30 years. Life history and population dynamics of this species are difficult to ascertain, because the birds nest at low densities across a broad range of habitat types. Between 1991 and 2004, we collected information on productivity and survival of long-tailed ducks at three locations...
Authors
Jason L. Schamber, Paul L. Flint, J. Barry Grand, Heather M. Wilson, Julie A. Morse
Enumeration of Pacific walrus carcasses on beaches of the Chukchi Sea in Alaska following a mortality event, September 2009 Enumeration of Pacific walrus carcasses on beaches of the Chukchi Sea in Alaska following a mortality event, September 2009
On September 14, 2009, we encountered substantial numbers of fresh walrus carcasses on the Alaskan shores of the Chukchi Sea near Icy Cape. We enumerated 131 carcasses using geo-referenced strip transect photography and visual counts of solitary carcasses. All appeared to be young animals based on review of aerial photographs and reference to 12 carcasses that we examined on the ground...
Authors
Anthony S. Fischbach, Daniel H. Monson, C.V. Jay
Europium-rich dark monazite - a potential new ore mineral for Alaska, USA? Europium-rich dark monazite - a potential new ore mineral for Alaska, USA?
No abstract available.
Authors
Richard B. Tripp, William Benzel, David T. Adams, Heather A. Lowers, Gregory K. Lee, Elizabeth A. Bailey
Application of the multi-dimensional surface water modeling system at Bridge 339, Copper River Highway, Alaska Application of the multi-dimensional surface water modeling system at Bridge 339, Copper River Highway, Alaska
The Copper River Basin, the sixth largest watershed in Alaska, drains an area of 24,200 square miles. This large, glacier-fed river flows across a wide alluvial fan before it enters the Gulf of Alaska. Bridges along the Copper River Highway, which traverses the alluvial fan, have been impacted by channel migration. Due to a major channel change in 2001, Bridge 339 at Mile 36 of the...
Authors
Timothy P. Brabets, Jeffrey S. Conaway
Preliminary geologic map of the Cook Inlet region, Alaska-Including parts of the Talkeetna, Talkeetna Mountains, Tyonek, Anchorage, Lake Clark, Kenai, Seward, Iliamna, Seldovia, Mount Katmai, and Afognak 1:250,000-scale quadrangles Preliminary geologic map of the Cook Inlet region, Alaska-Including parts of the Talkeetna, Talkeetna Mountains, Tyonek, Anchorage, Lake Clark, Kenai, Seward, Iliamna, Seldovia, Mount Katmai, and Afognak 1:250,000-scale quadrangles
The growth in the use of Geographic Information Systems (GIS) has highlighted the need for digital geologic maps that have been attributed with information about age and lithology. Such maps can be conveniently used to generate derivative maps for manifold special purposes such as mineral-resource assessment, metallogenic studies, tectonic studies, and environmental research. This report...
A case study of carbon fluxes from land change in the Southwest Brazilian Amazon A case study of carbon fluxes from land change in the Southwest Brazilian Amazon
Worldwide, land change is responsible for one-fifth of anthropogenic carbon emissions. In Brazil, three-quarters of carbon emissions originate from land change. This study represents a municipal-scale study of carbon fluxes from vegetation in Rio Branco, Brazil. Land-cover maps of pasture, forest, and secondary growth from 1993, 1996, 1999, and 2003 were produced using an unsupervised
Authors
K. Barrett, J. Rogan, J.R. Eastman
Detrital zircon geochronology of Cretaceous and Paleogene strata across the south-central Alaskan convergent margin Detrital zircon geochronology of Cretaceous and Paleogene strata across the south-central Alaskan convergent margin
Ages of detrital zircons are reported from ten samples of Lower Cretaceous to Paleogene metasandstones and sandstones from the Chugach Mountains, Talkeetna Mountains, and western Alaska Range of south-central Alaska. Zircon ages are also reported from three igneous clasts from two conglomerates. The results bear on the regional geology, stratigraphy, tectonics, and mineral resource...
Authors
Dwight Bradley, Peter J. Haeussler, Paul O'Sullivan, Rich Friedman, Alison Till, Dan Bradley, Jeff Trop
Channel incision and water-table decline along a recently rormed proglacial stream, Mendenhall Valley, southeastern Alaska Channel incision and water-table decline along a recently rormed proglacial stream, Mendenhall Valley, southeastern Alaska
Retreat of the Mendenhall Glacier, in southeastern Alaska, resulted in the formation of Mendenhall Lake, which has reduced the supply of coarse sediment to the proglacial Mendenhall River. Channel geometry surveys conducted in 1969 and 1998 over a 5.3 km reach of the Mendenhall River revealed reductions in mean bed elevations ranging from 0.4 to 1.5 meters based on cross sections...
Authors
Edward G. Neal