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Page 1772, results 44276 - 44300

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Use of habitats by female mallards wintering in Southwestern Louisiana
Paul T. Link, A. D. Afton, R. R. Cox Jr., B.E. Davis
2011, Waterbirds (34) 429-438
Habitat use by wintering Mallards (Anas platyrhychos) on the Gulf Coast Chenier Plain (GCCP) has received little study and quantitative data is needed for management of GCCP waterfowl. Radio-telemetry techniques were used to record habitats used by 135 female Mallards during winters 2004-2005 and 2005-2006 in south-western Louisiana. Habitat use...
Neoproterozoic extension in the greater dharwar craton: A reevaluation of the "betsimisaraka suture" in madagascar
R. D. Tucker, J.-Y. Roig, C. Delor, Y. Amlin, P. Goncalves, M.H. Rabarimanana, A.V. Ralison, R.W. Belcher
2011, Canadian Journal of Earth Sciences (48) 389-417
The Precambrian shield of Madagascar is reevaluated with recently compiled geological data and new U-Pb sensitive high-resolution ion microprobe (SHRIMP) geochronology. Two Archean domains are recognized: the eastern Antongil-Masora domain and the central Antananarivo domain, the latter with distinctive belts of metamafic gneiss and schist (Tsaratanana Complex). In the eastern...
San Andreas fault earthquake chronology and Lake Cahuilla history at Coachella, California
B. Philibosian, T. Fumal, R. Weldon
2011, Bulletin of the Seismological Society of America (101) 13-38
The southernmost ~100 km of the San Andreas fault has not ruptured historically. It is imperative to determine its rupture history to better predict its future behavior. This paleoseismic investigation in Coachella, California, establishes a chronology of at least five and up to seven major earthquakes during the past ~1100...
Characterization of the Cretaceous aquifer structure of the Meskala region of the Essaouira Basin, Morocco
L. Hanich, L. Zouhri, J. Dinger
2011, Journal of African Earth Sciences (59) 313-322
The aquifer of early Cretaceous age in the Meskala region of the Essaouira Basin is defined by interpretation of geological drilling data of oil and hydrogeological wells, field measurement and analysis of in situ fracture orientations, and the application of a morphostructural method to identify lineaments. These analyzes are used...
A behavior-oriented dynamic model for sandbar migration and 2DH evolution
K.D. Splinter, R.A. Holman, Nathaniel G. Plant
2011, Journal of Geophysical Research C: Oceans (116)
A nonlinear model is developed to study the time‐dependent relationship between the alongshore variability of a sandbar, a(t), and alongshore‐averaged sandbar position, xc(t). Sediment transport equations are derived from energetics‐based formulations. A link between this continuous physical representation and a parametric form describing the migration of sandbars of constant shape is established...
Cruise ships as a source of avian mortality during fall migration
Carol I. Bocetti
2011, Wilson Journal of Ornithology (123) 176-178
AAvian mortality during fall migration has been studied at many anthropogenic structures, most of which share the common feature of bright lighting. An additional, unstudied source of avian mortality during fall migration is recreational cruise ships that are brightly lit throughout the night. I documented a single mortality event of...
Early growth of Kohala volcano and formation of long Hawaiian rift zones
Peter W. Lipman, Andrew T. Calvert
2011, Geology (39) 659-662
Transitional-composition pillow basalts from the toe of the Hilo Ridge, collected from outcrop by submersible, have yielded the oldest ages known from the Island of Hawaii: 1138 ± 34 to 1159 ± 33 ka. Hilo Ridge has long been interpreted as a submarine rift zone of Mauna Kea, but the...
Hydrological mobilization of mercury and dissolved organic carbon in a snow-dominated, forested watershed: Conceptualization and modeling
J. Schelker, Douglas A. Burns, M. Weiler, H. Laudon
2011, Journal of Geophysical Research G: Biogeosciences (116)
The mobilization of mercury and dissolved organic carbon (DOC) during snowmelt often accounts for a major fraction of the annual loads. We studied the role of hydrological connectivity of riparian wetlands and upland/wetland transition zones to surface waters on the mobilization of Hg and DOC in Fishing Brook, a headwater...
Soil clay content underlies prion infection odds
W. David Walter, D.P. Walsh, Matthew L. Farnsworth, Dana L. Winkelman, M.W. Miller
2011, Nature Communications (2)
Environmental factors—especially soil properties—have been suggested as potentially important in the transmission of infectious prion diseases. Because binding to montmorillonite (an aluminosilicate clay mineral) or clay-enriched soils had been shown to enhance experimental prion transmissibility, we hypothesized that prion transmission among mule deer might also be enhanced in ranges with...
210Po in Nevada groundwater and its relation to gross alpha radioactivity
R. L. Seiler
2011, Ground Water (49) 160-171
Polonium-210 (210Po) is a highly toxic alpha emitter that is rarely found in groundwater at activities exceeding 1 pCi/L. 210Po activities in 63 domestic and public-supply wells in Lahontan Valley in Churchill County in northern Nevada, United States, ranged from 0.01 ± 0.005 to 178 ± 16 pCi/L with a...
Fish as major carbonate mud producers and missing components of the tropical carbonate factory
C.T. Perry, M.A. Salter, A.R. Harborne, S.F. Crowley, Howard L. Jelks, R.W. Wilson
2011, Proceedings of the National Academy of Sciences of the United States of America (108) 3865-3869
Carbonate mud is a major constituent of recent marine carbonate sediments and of ancient limestones, which contain unique records of changes in ocean chemistry and climate shifts in the geological past. However, the origin of carbonate mud is controversial and often problematic to resolve. Here we show that tropical marine...
Long-term biases in geomagnetic K and aa indices
Jeffrey J. Love
2011, Annales Geophysicae (29) 1365-1375
Analysis is made of the geomagnetic-activity aa index and its source K-index data from groups of ground-based observatories in Britain, and Australia, 1868.0–2009.0, solar cycles 11–23. The K data show persistent biases, especially for high (low) K-activity levels at British (Australian) observatories. From examination of multiple subsets of the K data we infer that the biases are not...
Rain pulse response of soil CO2 exchange by biological soil crusts and grasslands of the semiarid Colorado Plateau, United States
David R. Bowling, Edmund E. Grote, Jayne Belnap
2011, Journal of Geophysical Research G: Biogeosciences (116)
Biological activity in arid grasslands is strongly dependent on moisture. We examined gas exchange of biological soil crusts (biocrusts), the underlying soil biotic community, and the belowground respiratory activity of C3 and C4 grasses over 2 years in southeast Utah, USA. We used soil surface CO2 flux and the amount...
Deep long-period earthquakes beneath Washington and Oregon volcanoes
M.L. Nichols, S. D. Malone, Seth C. Moran, Weston A. Thelen, J.E. Vidale
2011, Journal of Volcanology and Geothermal Research (200) 116-128
Deep long-period (DLP) earthquakes are an enigmatic type of seismicity occurring near or beneath volcanoes. They are commonly associated with the presence of magma, and found in some cases to correlate with eruptive activity. To more thoroughly understand and characterize DLP occurrence near volcanoes in Washington and Oregon, we systematically...
CyberShake: A Physics-Based Seismic Hazard Model for Southern California
R. Graves, T.H. Jordan, S. Callaghan, E. Deelman, Edward H. Field, G. Juve, C. Kesselman, P. Maechling, G. Mehta, K. Milner, D. Okaya, P. Small, K. Vahi
2011, Pure and Applied Geophysics (168) 367-381
CyberShake, as part of the Southern California Earthquake Center’s (SCEC) Community Modeling Environment, is developing a methodology that explicitly incorporates deterministic source and wave propagation effects within seismic hazard calculations through the use of physics-based 3D ground motion simulations. To calculate a waveform-based seismic hazard estimate for a site of...
The effect of fire and permafrost interactions on soil carbon accumulation in an upland black spruce ecosystem of interior Alaska: Implications for post-thaw carbon loss
J. A. O'Donnell, J.W. Harden, A. D. McGuire, M.Z. Kanevskiy, M.T. Jorgenson, X. Xu
2011, Global Change Biology (17) 1461-1474
High‐latitude regions store large amounts of organic carbon (OC) in active‐layer soils and permafrost, accounting for nearly half of the global belowground OC pool. In the boreal region, recent warming has promoted changes in the fire regime, which may exacerbate rates of permafrost thaw and alter soil OC dynamics in...
Using normalized difference vegetation index to estimate carbon fluxes from small rotationally grazed pastures
R.H. Skinner, B.K. Wylie, T.G. Gilmanov
2011, Agronomy Journal (103) 972-979
Satellite-based normalized difference vegetation index (NDVI) data have been extensively used for estimating gross primary productivity (GPP) and yield of grazing lands throughout the world. However, the usefulness of satellite-based images for monitoring rotationally-grazed pastures in the northeastern United States might be limited because paddock size is often smaller than...
Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope: Coring operations, core sedimentology, and lithostratigraphy
K. Rose, R. Boswell, Timothy S. Collett
2011, Marine and Petroleum Geology (28) 311-331
In February 2007, BP Exploration (Alaska), the U.S. Department of Energy, and the U.S. Geological Survey completed the BPXA-DOE-USGS Mount Elbert Gas Hydrate Stratigraphic Test Well (Mount Elbert well) in the Milne Point Unit on the Alaska North Slope. The program achieved its primary goals of validating the pre-drill estimates...
Inter-specific coral chimerism: Genetically distinct multicellular structures associated with tissue loss in Montipora capitata
Thierry M. Work, Zac H. Forsman, Zoltan Szabo, Teresa D. Lewis, Greta S. Aeby, Robert J. Toonen
2011, PLoS ONE (6)
Montipora white syndrome (MWS) results in tissue-loss that is often lethal to Montipora capitata, a major reef building coral that is abundant and dominant in the Hawai'ian Archipelago. Within some MWS-affected colonies in Kane'ohe Bay, Oahu, Hawai'i, we saw unusual motile multicellular structures within gastrovascular canals (hereafter referred to as invasive gastrovascular...
Molecular detection of vertebrates in stream water: A demonstration using rocky mountain tailed frogs and Idaho giant salamanders
C.S. Goldberg, D. S. Pilliod, R.S. Arkle, L.P. Waits
2011, PLoS ONE (6)
Stream ecosystems harbor many secretive and imperiled species, and studies of vertebrates in these systems face the challenges of relatively low detection rates and high costs. Environmental DNA (eDNA) has recently been confirmed as a sensitive and efficient tool for documenting aquatic vertebrates in wetlands and in a large river...
Making United States Integrated Ocean Observing System (U.S. IOOS) inclusive of marine biological resources
H. Moustahfid, J. Potemra, P. Goldstein, R. Mendelssohn, A. Desrochers
2011, Conference Paper, OCEANS'11 - MTS/IEEE Kona, Program Book
An important Data Management and Communication (DMAC) goal is to enable a multi-disciplinary view of the ocean environment by facilitating discovery and integration of data from various sources, projects and scientific domains. United States Integrated Ocean Observing System (U.S. IOOS) DMAC functional requirements are based upon guidelines for standardized data...
Position of the Triassic-Jurassic boundary and timing of the end-Triassic extinctions on land: Data from the Moenave Formation on the southern Colorado Plateau, USA
S. G. Lucas, L.H. Tanner, L. Donohoo-Hurley, J. W. Geissman, H. W. Kozur, A.B. Heckert, Robert E. Weems
2011, Palaeogeography, Palaeoclimatology, Palaeoecology (302) 194-205
Strata of the Moenave Formation on and adjacent to the southern Colorado Plateau in Utah–Arizona, U.S.A., represent one of the best known and most stratigraphically continuous, complete and fossiliferous terrestrial sections across the Triassic–Jurassic boundary. We present a synthesis of new biostratigraphic and magnetostratigraphic data collected from across the Moenave...
Improving occupancy estimation when two types of observational error occur: Non-detection and species misidentification
David Miller, James D. Nichols, B.T. McClintock, Evan H. Campbell Grant, L.L. Bailey, L.A. Weir
2011, Ecology (92) 1422-1428
Efforts to draw inferences about species occurrence frequently account for false negatives, the common situation when individuals of a species are not detected even when a site is occupied. However, recent studies suggest the need to also deal with false positives, which occur when species are misidentified so that a...
Late Holocene slip rate of the San Andreas fault and its accommodation by creep and moderate-magnitude earthquakes at Parkfield, California
N.A. Toke, J.R. Arrowsmith, Michael J. Rymer, A. Landgraf, D.E. Haddad, M. Busch, J. Coyan, A. Hannah
2011, Geology (39) 243-246
Investigation of a right-laterally offset channel at the Miller's Field paleoseismic site yields a late Holocene slip rate of 26.2 +6.4/−4.3 mm/yr (1σ) for the main trace of the San Andreas fault at Parkfield, California. This is the first well-documented geologic slip rate between the Carrizo and creeping sections of...
Fish community and bioassessment responses to stream network position
N.P. Hitt, P. L. Angermeier
2011, Journal of the North American Benthological Society (30) 296-309
If organisms move beyond the boundaries of local sampling units, regional metacommunity dynamics could undermine the ability of bioassessment studies to characterize local environmental quality. We tested the prediction that fish dispersal influences local fish community structure and bioassessment metrics as a function of site position within stream networks. We...