Skip to main content
U.S. flag

An official website of the United States government

Articles

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.

Filter Total Items: 74057

Non-mercury methylating microbial taxa are integral to understanding links between mercury methylation and elemental cycles in marine and freshwater sediments

The goal of this study was to explore the role of non-mercury (Hg) methylating taxa in mercury methylation and to identify potential links between elemental cycles and Hg methylation. Statistical approaches were utilized to investigate the microbial community and biochemical functions in relation to methylmercury (MeHg) concentrations in marine and freshwater sediments. Sediments were collected fr
Authors
Yong-Li Wang, Kaoru Ikuma, Scott C. Brooks, Matthew S. Varonka, Amrika Deonarine

20th century warming in the lower Florida Keys was dominated by increasing winter temperatures

Long-lived Atlantic coral species like Orbicella faveolata are important archives of oceanographic change in shallow, marine environments like the Florida Keys. Not only can coral-based records extend for multiple centuries beyond the limits of the instrumental record, but they can also provide a more accurate representation of in situ conditions than gridded interpolated sea-surface temperature (
Authors
Jennifer A. Flannery, Julie N. Richey, Lauren Toth, Madelyn Jean Mette

Urbanization and water management control stream water quality along a mountain to plains transition

Urbanization can have substantial effects on water quality due to altered hydrology and introduction of constituents to water bodies. In arid and semi-arid environments, streams are further stressed by dewatering as a result of diversions. We conducted a high-resolution synoptic survey of two streams in Colorado, USA that transition abruptly from granitic/metamorphic forested mountains to sediment
Authors
Sheila F. Murphy, Robert L. Runkel, Edward G. Stets, Alex J Nolan, Deborah A. Repert

USGS and social media user dialogue and sentiment during the 2018 eruption of Kīlauea Volcano, Hawaii

Responsive and empathic communication by scientists is critical for building trust and engagement with communities, which, in turn, promotes receptiveness toward authoritative hazard information during times of crisis. The 2018 eruption of Hawai‘i's Kīlauea Volcano was the first volcanic crisis event in which communication via the U.S. Geological Survey (USGS) social media group, “USGS Volcanoes,”
Authors
Robert T. Goldman, Sara McBride, Wendy K. Stovall, David Damby

Determinants of spring migration departure dates in a New World sparrow: Weather variables reign supreme

Numerous factors influence the timing of spring migration in birds, yet the relative importance of intrinsic and extrinsic variables on migration initiation remains unclear. To test for interactions among weather, migration distance, parasitism, and physiology in determining spring departure date, we used the Dark-eyed Junco (Junco hyemalis) as a model migratory species known to harbor diverse and
Authors
Allison J. Byrd, Katherine M. Talbott, Tara M. Smiley, Taylor B. Verrett, Michael S. Gross, Michelle Hladik, Ellen D. Ketterson, Daniel J. Becker

Stable isotopes reveal that foraging strategy dictates trophic response of salt marsh residents to black mangrove Avicennia germinans range expansion

Climate warming has facilitated the expansion of black mangrove Avicennia germinans (hereafter ‘Avicennia’) into smooth cordgrass Spartina alterniflora (hereafter ‘Spartina’) salt marshes in southeastern Louisiana (USA). As macrophytes contribute to soil organic matter (SOM) and primary production, this transition could alter the basal energy pathways supporting salt marsh food webs. We used bulk-
Authors
Katherine B. Loesser, Christina E. Powell, Brandeus Davis, Melissa Millman Baustian, Michael J. Polito

Strong variation in Brook Trout trends across geology, elevation, and stream size in Shenandoah National Park

ObjectiveLandscape context structures fish abundance and dynamics, and understanding trends in fish abundance across the landscape is often prerequisite for effective conservation. In this study, we evaluated the status and trends of Brook Trout Salvelinus fontinalis in Shenandoah National Park to understand how these are structured across bedrock geology, elevation, and stream size.MethodsWe used
Authors
Evan S. Childress, David E Demarest, John E.B. Wofford, Nathaniel P. Hitt, Benjamin Letcher

A biodynamic model predicting copper and cadmium bioaccumulation in caddisflies: Linkages between field studies and laboratory exposures

Hydropsyche and Arctopsyche are filter-feeding caddisflies (Order: Trichoptera; Family: Hydropsychidae) that are commonly used to monitor metal exposures in rivers. While tissue residue concentrations provide important bioaccumulation data regarding metal bioavailability, they do not provide information regarding the mechanisms of uptake and loss, or exposure history. This study examined the physi
Authors
Michelle I. Hornberger

Wildfire burn severity and stream chemistry influence aquatic invertebrate and riparian avian mercury exposure in forested ecosystems

Terrestrial soils in forested landscapes represent some of the largest mercury (Hg) reserves globally. Wildfire can alter the storage and distribution of terrestrial-bound Hg via reemission to the atmosphere or mobilization in watersheds where it may become available for methylation and uptake into food webs. Using data associated with the 2007 Moonlight and Antelope Fires in California, we examin
Authors
Garth Herring, Lora B. Tennant, James Willacker, Matthew Johnson, Rodney B. Siegel, Julie S. Polasik, Collin Eagles-Smith

Outcomes of control and monitoring of a widespread riparian invader (Tamarix spp.): A comparison of synthesis approaches

Effective ecological restoration requires empirical assessment to determine outcomes of projects, but conclusions regarding the effects of restoration treatments on the whole ecosystem remain rare. Control of invasive shrubs and trees in the genus Tamarix and associated riparian restoration in the American Southwest has been of interest to scientists and resource managers for decades; dozens of st
Authors
Alexander R.B. Goetz, Eduardo Gonzalez-Sargas, Mayra C. Vidal, Patrick B. Shafroth, Annie L. Henry, Anna A. Sher

Upper limits for post-wildfire floods and distinction from debris flows

Upper magnitude limits and scaling with basin size for post-wildfire floods are unknown. An envelope curve was estimated defining post-wildfire flood upper limits as a function of basin area. We show the importance of separating peak flows by floods versus debris flows. Post-wildfire flood maxima are a constant 43 m3 s−1 km−2 for basins from 0.01 to 23 to 34 km2 and then declining with added basin
Authors
Brian A. Ebel

Tracking cycles of Phanerozoic opening and closing of ocean basins using detrital rutile and zircon geochronology and geochemistry

Sedimentary basins provide a deep time archive of tectonic and Earth-surface processes that can be leveraged by detrital mineral U-Pb dating and geochemistry to track paleogeography, magmatism, and crustal evolution. Zircon preserves the long-term (billions of years) record of supercontinent cycles; however, it is biased toward preserving felsic crustal records. Detrital rutile complements the det
Authors
Margaret L. Odlum, Tomas N. Capaldi, Kelly David Thomson, Daniel F. Stockli