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Browse more than 65,000 articles authored by our scientists over the past 100+ year history of the USGS and refine search by topic, location, year, and advanced search.

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Assimilation efficiency of rainbow trout fed natural diets Assimilation efficiency of rainbow trout fed natural diets

Assimilation efficiency is a critical assumption of stable isotope mixing models and bioenergetics models, yet few studies examine how assimilation efficiency influences modeling inferences. We conducted laboratory experiments to determine rainbow trout (Oncorhynchus mykiss) assimilation efficiencies. Assimilation efficiency averaged 55.8% (SE ± 0.90) and 64.5% (SE ± 1.98) at the 10% and...
Authors
Jon M. Flinders, Daniel D. Magoulick

Foraging benefits promote fitness in migratory mule deer Foraging benefits promote fitness in migratory mule deer

Although migration is widespread among ungulates, the fitness benefits associated with different migratory tactics have rarely been documented. Here, we evaluated a 9-year dataset on a migratory population of mule deer to test the hypothesis that long-distance migration provides access to seasonal forage which translates into demographic benefits. Mule deer that migrated long (>130 km)...
Authors
Anna C. Ortega, Tayler N. LaSharr, Patrick W. Burke, Patrick Lionberger, Miguel Valdez, Kevin L. Monteith, Matthew J. Kauffman

New methods provide a 300–year perspective on modern area burned in two wilderness areas of the southwest United States New methods provide a 300–year perspective on modern area burned in two wilderness areas of the southwest United States

Climate change, expanding human ignitions, and increased fuels from fire exclusion are driving increases in area burned and fire severity in dry conifer forests of the western United States. Increasing area burned is occurring against the backdrop of a large fire deficit caused by over a century of fire exclusion. A key land management question is whether historically frequent fire...
Authors
Calvin A. Farris, Ellis Q. Margolis, Jose Iniguez, D.A. Falk, K. Gerow, C.H. Baisan, C.D. Allen, T.W. Swetnam

Simulated ground motion dataset in the Azores Plateau, Portugal, on rock and soil sites Simulated ground motion dataset in the Azores Plateau, Portugal, on rock and soil sites

Building on a previously developed bedrock dataset, this study extends the Azores Plateau ground motion simulations to include soil-amplified records and introduces a comprehensive validation framework. Soil amplification is modeled using one-dimensional soil profiles. A stochastic source-based approach is employed to generate the dataset, incorporating randomization of input-model...
Authors
Shaghayegh Karimzadeh, S.M. Sajad Hussaini, Daniel Caicedo, Alexandra Carvalho, Sanaz Rezaeian, Paulo B. Lourenco

Estimating paleotemperature using stable isotopes of soil-formed phyllosilicates from paleosols: A review Estimating paleotemperature using stable isotopes of soil-formed phyllosilicates from paleosols: A review

Fossilized soils, or paleosols, contain soil-formed phyllosilicates whose stable isotopic compositions may be used to calculate paleotemperature and thus reconstruct ancient terrestrial environments. Though paleosols are common in the geologic record, the use of phyllosilicates as paleotemperature proxies is limited in the literature owing to difficulties with selecting optimal paleosols
Authors
Kate Andrzejewski, Julia A. McIntosh, Erik L. Gulbranson, Daniel Ibarra

Integrating climate and anthropogenic dynamics can inform multifaceted management for declining mule deer populations Integrating climate and anthropogenic dynamics can inform multifaceted management for declining mule deer populations

Wildlife and their habitats face profound challenges from climate and landscape-scale changes that extend beyond the influence and time horizon of most biologists and land managers. In this changing environment, long-term datasets can enhance assessments of how demographic trends respond to interactions among local (e.g., habitat restoration decisions) and broad extent drivers, including...
Authors
Teagan A. Hayes, Aaron N. Johnston, L. Embere Hall, Jill E. Randall, Matthew J. Kauffman, Christopher Keefe, Kevin Monteith, Tabitha A. Graves

Origin of the Pd/Pt ratio of the J-M Reef, Stillwater Complex, Montana, USA Origin of the Pd/Pt ratio of the J-M Reef, Stillwater Complex, Montana, USA

The J-M reef of the Stillwater Complex is characterized by a high Pd/Pt ratio (mean ~3.8 with a standard error of 0.03) with a homogeneous geospatial distribution at the deposit scale. In this contribution, we demonstrate that the Pd/Pt ratio of the reef is the product of equilibration of an immiscible sulfide liquid with a silicate melt rich in Pd relative to Pt. Despite the high tenors...
Authors
Michael Jenkins, William D. Smith

Long- versus short-term changes in seafloor elevation and volume of the Upper Florida Keys Reef Tract: 1935–2002 and 2002–2016 Long- versus short-term changes in seafloor elevation and volume of the Upper Florida Keys Reef Tract: 1935–2002 and 2002–2016

Coral reefs provide immense ecosystem and economic value, supporting biodiversity, fisheries, tourism, and coastal protection worth billions annually. However, widespread degradation from thermal stress, storms, disease, and human impacts has caused significant coral cover and reef structure loss, increasing coastal vulnerability and economic risks. While coral loss is well-documented...
Authors
Selena Anne-Marie Johnson, David G. Zawada, Kimberly Yates, Connor Monroe Jenkins

Understanding the resource potential of natural hydrogen on Earth: Scientific gaps, uncertainties and recommendations Understanding the resource potential of natural hydrogen on Earth: Scientific gaps, uncertainties and recommendations

A comprehensive scientific research roadmap is essential to bridge knowledge gaps and deepen the understanding of key geological, geochemical, and geophysical aspects of natural hydrogen (H2) as a potential new energy resource. This paper reviews major scientific uncertainties on natural H2, suggesting research priorities, as a guide for defining exploration strategies, techniques, and...
Authors
Giuseppe Etiope, Geoffrey S. Ellis, Omid H. Ardakani, Christopher J. Boreham, Peter Klitzke, Antonio Martín-Monge, Humberto L.S. Reis, Alexis S. Templeton, Hyeong Soo Kim, Eric Gaucher, Olivier Sissmann

Drinking water arsenic, urinary arsenic biomarkers, and cognitive impairment in the REGARDS study Drinking water arsenic, urinary arsenic biomarkers, and cognitive impairment in the REGARDS study

BackgroundThere are several pathways by which inorganic arsenic (iAs) exposure can affect cognition among adults. Few epidemiologic studies evaluate iAs in water and inter-individual differences in urinary arsenic toxicokinetics. We aimed to estimate the association between individual-level urinary arsenic biomarkers, county-level iAs in drinking water, and cognitive impairment in a...
Authors
Meghan Angley, Yijia Zhang, Anne E. Nigra, Melissa A. Lombard, Matthew O. Gribble, Liping Lu, Frederick W. Unverzagt, Leslie A. McClure, Suzanne E. Judd, Mary Cushman, John Brockman, Ka Kahe

Hakalau’s moving castle: How climate change and restoration are shifting an island fortress for forest birds Hakalau’s moving castle: How climate change and restoration are shifting an island fortress for forest birds

Hakalau Forest Unit of the Big Island National Wildlife Refuge Complex (hereafter, Hakalau) protects the largest area with the highest endemic forest bird diversity in Hawaiʻi, including four federally listed species. Hakalau’s higher elevation montane forest provides refuge from avian malaria (Plasmodium relictum), a primary driver of Hawaiian honeycreeper extinctions. However, recent...
Authors
Noah Hunt, Steve Kendall, Trevor Bak, Lucas B. Fortini, Richard J. Camp

Constraining the onset of carboniferous cyclicity in the Arkoma Basin of the Midcontinent, North America: Implications for calibrating a globally significant latest Bashkirian transgression Constraining the onset of carboniferous cyclicity in the Arkoma Basin of the Midcontinent, North America: Implications for calibrating a globally significant latest Bashkirian transgression

Cyclothems are defined by the repeat juxtaposition of littoral and open marine successions over short stratigraphic distances (meters to 10's of meters) and are interpreted to be driven by glacioeustatic forcing of sea level during the late Paleozoic Ice Age. The concept of cyclothems was defined in the Midcontinent region of the United States. However, correlating the Midcontinent...
Authors
Neil Patrick Griffis, Marieke Dechesne, Tyson Michael Smith, Mark R. Hudson, Charles M. Henderson, Roland Mundil, Mikel Shinn, Justin E. Birdwell, Laura Pianowski, Brandon Michael Lutz, Cameron Mark Mercer, Leah E. Morgan, Leland R. Spangler
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