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At least 1,009 records · Page 56Linked to original sources
USGS2016

Genetic structure of faucet snail, Bithynia tentaculata populations in North Americal based on microsattelite markers

Bithynia tentaculata is believed to have been extirpated from North America during the last glacial maximum. It was reintroduced into North America via the Great Lakes basin in the 1800’s and has recently been expanding its geographic range. This snail serves as intermediate host for three trematodes that cause extensive recurring morbidity and mortality events in migratory water birds along the Mississippi River. Using twelve microsatellite loci for ~200 individual snails from 11 populations in North America and Europe, we examined one of the three major geographic regions from which founding populations into the Great Lakes typically originate. Our data supports a single recolonization of North America into the Great Lakes Basin followed by subsequent introduction events from the Great Lakes to other large watersheds in North America. However, additional watersheds in Europe require sampling to confirm this result. No populations with genetic signatures indicative of North American glacial relics were found. The initial invasion of North America was likely not from the Ponto-Caspian basin, the usual source of freshwater invasive species to the Laurentian Great Lakes.

Freshwater Mollusk Biology and Conservation↗
USGS2010

Projected climate impacts for the amphibians of the western hemisphere

Given their physiological requirements, limited dispersal abilities, and hydrologically sensitive habitats, amphibians are likely to be highly sensitive to future climatic changes. We used three approaches to map areas in the western hemisphere where amphibians are particularly likely to be affected by climate change. First, we used bioclimatic models to project potential climate-driven shifts in the distribution of 413 amphibian species based on 20 climate simulations for 2071–2100. We summarized these projections to produce estimates of species turnover. Second, we mapped the distribution of 1099 species with restricted geographic ranges. Finally, using the 20 future climate-change simulations, we mapped areas that were consistently projected to receive less seasonal precipitation in the coming century and thus were likely to have altered microclimates and local hydrologies. Species turnover was projected to be highest in the Andes Mountains and parts of Central America and Mexico, where, on average, turnover rates exceeded 60% under the lower of two emissions scenarios. Many of the restricted-range species not included in our range-shift analyses were concentrated in parts of the Andes and Central America and in Brazil's Atlantic Forest. Much of Central America, southwestern North America, and parts of South America were consistently projected to experience decreased precipitation by the end of the century. Combining the results of the three analyses highlighted several areas in which amphibians are likely to be significantly affected by climate change for multiple reasons. Portions of southern Central America were simultaneously projected to experience high species turnover, have many additional restricted-range species, and were consistently projected to receive less precipitation. Together, our three analyses form one potential assessment of the geographic vulnerability of amphibians to climate change and as such provide broad-scale guidance for directing conservation efforts.

Conservation Biology↗
USGS2016

Evidence for common ancestry among viruses isolated from wild birds in Beringia and highly pathogenic intercontinental reassortant H5N1 and H5N2 influenza A viruses

Highly pathogenic clade 2.3.4.4 H5N8, H5N2, and H5N1 influenza A viruses were first detected in wild, captive, and domestic birds in North America in November–December 2014. In this study, we used wild waterbird samples collected in Alaska prior to the initial detection of clade 2.3.4.4 H5 influenza A viruses in North America to assess the evidence for: (1) dispersal of highly pathogenic influenza A viruses from East Asia to North America by migratory birds via Alaska and (2) ancestral origins of clade 2.3.4.4 H5 reassortant viruses in Beringia. Although we did not detect highly pathogenic influenza A viruses in our sample collection from western Alaska, we did identify viruses that contained gene segments sharing recent common ancestry with intercontinental reassortant H5N2 and H5N1 viruses. Results of phylogenetic analyses and estimates for times of most recent common ancestry support migratory birds sampled in Beringia as maintaining viral diversity closely related to novel highly pathogenic influenza A virus genotypes detected in North America. Although our results do not elucidate the route by which highly pathogenic influenza A viruses were introduced into North America, genetic evidence is consistent with the hypothesized trans-Beringian route of introduction via migratory birds.

Infection, Genetics and Evolution↗
USGS2012

Inoculation of bats with European Geomyces destructans supports the novel pathogen hypothesis for the origin of white-nose syndrome

White-nose syndrome (WNS) is an emerging disease of hibernating bats associated with cutaneous infection by the fungus Geomyces destructans ( Gd ), and responsible for devastating declines of bat populations in eastern North America. Affected bats appear emaciated and one hypothesis is that they spend too much time out of torpor during hibernation, depleting vital fat reserves required to survive the winter. The fungus has also been found at low levels on bats throughout Europe but without mass mortality. This finding suggests that Gd is either native to both continents but has been rendered more pathogenic in North America by mutation or environmental change, or that it recently arrived in North America as an invader from Europe. Thus, a causal link between Gd and mortality has not been established and the reason for its high pathogenicity in North America is unknown. Here we show that experimental inoculation with either North American or European isolates of Gd causes WNS and mortality in the North American bat, Myotis lucifugus . In contrast to control bats, individuals inoculated with either isolate of Gd developed cutaneous infections diagnostic of WNS, exhibited a progressive increase in the frequency of arousals from torpor during hibernation, and were emaciated after 3–4 mo. Our results demonstrate that altered torpor-arousal cycles underlie mortality from WNS and provide direct evidence that Gd is a novel pathogen to North America from Europe.

Proceedings of the National Academy of Sciences↗
USGS2020

Climate- versus geographic-dependent patterns in the spatial distribution ofmacroinvertebrate assemblages in New World depressional wetlands

Analyses of biota at lower latitudes may presage impacts of climate change on biota at higher latitudes. Macroinvertebrate assemblages in depressional wetlands may be especially sensitive to climate change because weather‐related precipitation and evapotranspiration are dominant ecological controls on habitats, and organisms of depressional wetlands are temperature‐sensitive ectotherms. We aimed to better understand how wetland macroinvertebrate assemblages were structured according to geography and climate. To do so, we contrasted aquatic‐macroinvertebrate assemblage structure (family level) between subtropical and temperate depressional wetlands of North and South America using presence–absence data from 264 of these habitats across the continents and more‐detailed relative‐abundance data from 56 depressional wetlands from four case‐study locations (North Dakota and Georgia in North America; southern Brazil and Argentinian Patagonia in South America). Both data sets roughly partitioned wetland numbers equally between the two climatic zones and between the continents. We used ordination methods (PCA and NMDS) and tests of multivariate dispersion (PERMDISP) to assess the distribution and the homogeneity in variation in the composition of macroinvertebrate assemblages across climates and continents, respectively. We found that macroinvertebrate assemblage structures in the subtropical depressional wetlands of North and South America were similar to each other (at the family level), while assemblages in the North and South American temperate wetlands were unique from the subtropics, and from each other. Tests of homogeneity of multivariate dispersion indicated that family‐level assemblage structures were more homogeneous in wetlands from the subtropical than the temperate zones. Our study suggests that ongoing climate change may result in the homogenization of macroinvertebrate assemblage structures in temperate zones of North and South America, with those assemblages becoming enveloped by assemblages from the subtropics. Biotic homogenization, more typically associated with other kinds of anthropogenic factors, may also be affected by climate change.

Global Change Biology↗
USGS2021

Mycobiome traits associated with disease tolerance predict many western North American bat species will be susceptible to white-nose syndrome

White-nose syndrome (WNS), a fungal disease that has caused catastrophic population declines of bats in eastern North America, is rapidly spreading across the continent and now threatens previously unexposed bat species in western North America. The causal agent of WNS, the fungus Pseudogymnoascus destructans , can infect many species of hibernating bats, but susceptibility to WNS varies by host species. We previously reported that certain traits of the skin microbiome, particularly yeast diversity and abundance, of bat species in eastern North America are strongly associated with resistance to WNS. Using these traits, we developed models to predict WNS susceptibility of 13 species of western North American bats. Based on models derived from yeast species diversity, only one bat species, Myotis velifer , was predicted to be WNS resistant (i.e., may develop the disease, but with low mortality rates). We also screened yeasts found on western bats for P. destructans -antagonistic properties by spore germination and growth inhibition/competition assays and found the ability of yeasts to inhibit P. destructans in vitro to be strain specific. Similar to results of inhibition assays performed with yeasts isolated from bats in eastern North America, few yeasts isolated from bats in western North America inhibited P. destructans in vitro. Continued monitoring of western bat populations will serve to validate the accuracy of the mycobiome analysis in predicting WNS susceptibility, document population and susceptibility trends, and identify additional predictors to assess the vulnerability of naive bat populations to WNS.

Microbilogy Spectrum↗
USGS2006

Biodiversity management of fens and fen meadows by grazing, cutting and burning

Question: Can the biodiversity of fens in Europe and North America be maintained through the use of grazing (especially cattle grazing), fire, and/or cutting? Location: European and North American fens. Methods: This paper is a review of the literature on the effects of grazing, fire and cutting on fens, to explore the relationship between management and biodiversity in fens. Results: A reduction of cattle grazing, mowing and burning in fens has led to a reduction in biodiversity in fens. The vegetation of abandoned fens shifts to trees and shrubs after 10-15 years, which shade the smaller and rarer species of these wetlands. While careful use of fire is used to manage fens in North America, it is not widely used in European fens, perhaps because the peat of drained fens may catch fire. Cattle grazing cannot be considered a natural disturbance in North America, since cattle did not evolve on that continent. In Europe, cattle do not generally graze in unaltered fens, but they do use slightly drained fen meadows. Conclusions: Three approaches have been used to control the dominance of tall woody and herbaceous species in abandoned fens, including the re-introduction of cattle, mowing, and burning. Overgrazing results in a permanent reduction in biodiversity, therefore cattle re-introduction must be approached cautiously. In Europe, but not in North America, mowing has been an important management tool, and mowing has been successful in maintaining species richness, particularly in fens that have been mowed annually for centuries. Fire has been the most common and successful management tool in North America although it is not effective in removing shrubs that have become large. Because the problems and solutions are similar, the literature of both European and North American fen management can be analyzed to better assess the management of fens on both continents. Many management questions require further study and these are listed in the paper. ?? IAVS; Opulus Press.

Conference Paper↗
USGS2006

A unified strategy for monitoring changes in abundance of birds associated with North American tidal marshes

An effective approach to species conservation involves efforts to prevent species from becoming threatened with extinction before they become listed as endangered. Standardized monitoring efforts provide the data necessary to estimate population trajectories of many species so that management agencies can identify declining species before they reach the point of endangerment. Species that occur in tidal saltmarshes in North America are under sampled by existing broad-scale monitoring programs. We summarize existing local and regional survey efforts for saltmarsh birds and propose a standardized continental protocol for assessing the status and population trends of birds that breed in saltmarshes in North America. The objective of this proposed survey effort is to create a series of interconnected monitoring efforts that will provide information on the status and the changes in status of terrestrial birds living in saltmarsh systems of North America. We describe detailed field protocols for standardized surveys of saltmarsh birds across North America. We recommend morning point-count surveys with an initial 5-min passive period followed by a period of call broadcast. Surveyors record all individual birds detected (regardless of distance) for all species that are associated with saltmarshes and estimate the distance to each individual bird detected. We provide recommendations for standardizing distance between adjacent survey points, how repeat detections across points are recorded, daily and seasonal timing of surveys, timing of surveys relative to tidal cycles, number of replicate surveys per year, and focal species for this standardized survey effort. Recommended survey protocols include methods that allow estimation of various components of detection probability so that stronger inferences can be made based on trends in count data. We explain why the various survey recommendations are made so that potential participants understand the rationale for various aspects of the survey protocols. We also provide sample data forms and an example of how to fill out a data form. These protocols build upon the Standardized North American Marsh-Bird Monitoring Protocols by encouraging those interested in saltmarsh passerines (and other saltmarsh birds) to conduct surveys using a standardized protocol similar to that being used for secretive marsh birds. Standardization of this sort will allow data from surveys focusing on saltmarsh passerines to be easily pooled with data from surveys focusing on secretive marsh birds. Implementing these standardized surveys in saltmarshes across North America will help document regional and continental patterns in distribution and abundance of all birds associated with tidal marshes.

Book chapter↗
USGS2007

Workshop: Western hemisphere network of bird banding programs

Purpose: To promote collaboration among banding programs in the Americas. Introduction: Bird banding and marking provide indispensable tools for ornithological research, management, and conservation of migratory birds on migratory routes, breeding and non-breeding grounds. Many countries and organizations in Latin America and the Caribbean are in the process of developing or have expressed interest in developing national banding schemes and databases to support their research and management programs. Coordination of developing and existing banding programs is essential for effective data management, reporting, archiving and security, and most importantly, for gaining a fuller understanding of migratory bird conservation issues and how the banding data can help. Currently, there is a well established bird-banding program in the U.S.A. and Canada, and programs in other countries are being developed as well. Ornithologists in many Latin American countries and the Caribbean are interested in using banding and marking in their research programs. Many in the ornithological community are interested in establishing banding schemes and some countries have recently initiated independent banding programs. With the number of long term collaborative and international initiatives increasing, the time is ripe to discuss and explore opportunities for international collaboration, coordination, and administration of bird banding programs in the Western Hemisphere. We propose the second ?Western Hemisphere Network of Bird Banding Programs? workshop, in association with the SCSCB, to be an essential step in the progress to strengthen international partnerships and support migratory bird conservation in the Americas and beyond. This will be the second multi-national meeting to promote collaboration among banding programs in the Americas (the first meeting was held in October 8-9, 2006 in La Mancha, Veracruz, Mexico). The Second ?Western Hemisphere Network of Bird Banding Programs? workshop will continue addressing issues surrounding the coordination of an Americas? approach to bird banding and will review in detail the advances made on the first workshop such as, coordination of bands and markers, coordination in recovery reporting, permit issues, data management and data sharing and archiving, data security, training, etc. Workshop Goals: Build on accomplishments of the network?s first workshop (Oct 8-9, 2006). Identify and explore new opportunities for data sharing, data archiving, data access, training, etc. Initiate strategies to support international collaboration and coordination amongst bird banding programs in the Western Hemisphere. Workshop structure: One day workshop of guided discussions. Participants: Representatives of government agencies, program managers and NGOs.

Book chapter↗
USGS2008

Ticks

The most common vector-borne diseases in both Europe and North America are transmitted by ticks. Lyme borreliosis (LB), a tick-borne bacterial zoonosis, is the most highly prevalent. Other important tick-borne diseases include TBE (tick-borne encephalitis) and Crimean-Congo haemorrhagic fever in Europe, Rocky Mountain spotted fever (RMSF) in North America, and numerous less common tick-borne bacterial, viral, and protozoan diseases on both continents. The major etiological agent of LB is Borrelia burgdorferi in North America, while in Europe several related species of Borrelia can also cause human illness. These Borrelia genospecies differ in clinical manifestations, ecology (for example, some have primarily avian and others primarily mammalian reservoirs), and transmission cycles, so the epizootiology of LB is more complex in Europe than in North America. Ticks dwell predominantly in woodlands and meadows, and in association with animal hosts, with only limited colonization of human dwellings by a few species. Therefore, suburbanization has contributed substantially to the increase in tick-borne disease transmission in North America by fostering increased exposure of humans to tick habitat. The current trend toward suburbanization in Europe could potentially result in similar increases in transmission of tick-borne diseases. Incidence of tick-borne diseases can be lowered by active public education campaigns, targeted at the times and places of greatest potential for encounter between humans and infected ticks. Similarly, vaccines (e.g., against TBE) are most effective when made available to people at greatest risk, and for high-prevalence diseases such as LB. Consultation with vector-borne disease experts during the planning stages of new human developments can minimize the potential for residents to encounter infected ticks (e.g., by appropriate dwelling and landscape design). Furthermore, research on tick vectors, pathogens, transmission ecology, and on geographic distribution, spread, and management of tick-borne diseases can lead to innovative and improved methods to lower the incidence of these diseases. Surveillance programs to monitor the distribution and spread of ticks, associated pathogens, and their reservoirs, can allow better-targeted management efforts, and provide data to assess effectiveness and to improve management programs.

Book chapter↗
USGS2012

Coastal wetlands of Chesapeake Bay

Wetlands are prominent landscapes throughout North America. The general characteristics of wetlands are controversial, thus there has not been a systematic assessment of different types of wetlands in different parts of North America, or a compendium of the threats to their conservation. Wetland Habitats of North America adopts a geographic and habitat approach, in which experts familiar with wetlands from across North America provide analyses and syntheses of their particular region of study. Addressing a broad audience of students, scientists, engineers, environmental managers, and policy makers, this book reviews recent, scientifically rigorous literature directly relevant to understanding, managing, protecting, and restoring wetland ecosystems of North America.

Book chapter↗
USGS2002

United States streamflow probabilities and uncertainties based on anticipated El Niño, water year 2003

During the course of spring and summer 2002, tropical sea-surface temperatures in the eastern Pacific Ocean have warmed and the wind and pressure fields have shifted, so that by August, there was considerable confidence that water year (October–September) 2003 will be characterized by a weak to mild El Niño climate (http://iri.columbia.edu/climate/ENSO/currentinfo/archive/200208/QuickLook.html). At the same time, the Pacific Decadal Oscillation pattern of sea-surface temperatures in the North Pacific (Mantua et al., 1997) has shifted towards a more neutral state than in the past several years and will not be considered in detail here. Previous studies of the connections between El Niños and streamflow in the United States by the authors (e.g., Redmond and Koch, 1991; Cayan and Webb, 1992; Cayan et al., 1999; Dettinger et al., 2001) indicate that El Niño conditions influence historical streamflow distributions to varying extents. These conclusions, along with those of other researchers, suggest that foreknowledge of El Niño conditions can inform seasonal outlooks for streamflows throughout the Americas and elsewhere. For example, Dettinger et al. (2001), as distilled here into Fig. 1, showed that historical annual streamflow totals have correlated negatively with the Southern Oscillation Index (SOI, which is negatively associated with El Niños) in the U.S. Southwest as well as in the subtropics of South America, and correlate positively in the U.S. Northwest, in much of tropical South America, and, perhaps, in southernmost South America. These interhemispheric bands of El Niño influence are a matter of considerable concern for water- and land-managers throughout the Americas, and expand upon results from previous studies in the western United States (e.g., Redmond and Koch, 1991; Cayan and Webb, 1992), including a recent analysis by Pizarro and Lall (2002), where water availability and hydrologic extremes are particularly pressing issues.

Experimental Long-Lead Forecast Bulletin↗
USGS2016

Animated tectonic reconstruction of the Lower Colorado River region: Implications for Late Miocene to Present deformation

Although the majority of late Miocene to present Pacific-North America plate boundary strain has been accommodated by faults of the San Andreas and Gulf of California systems, growing evidence of dextral shear east of the San Andreas Fault indicates that a component of plate boundary deformation occurred in the lower Colorado River (LoCR) region. Large-scale tectonic reconstructions across the Gulf of California and Salton Trough (GCAST) region (Fig. 1), a ~500 km-wide zone of deformation that affected the western margin of North America, provide important constraints on the location, timing, style, and magnitude of crustal deformation in the LoCR region (Fig. 2). Characterizing Miocene to present deformation in the LoCR region is important to resolve the presence and kinematics of upper crustal structures that accommodated intracontinental strain and improves our understanding of the processes that promoted localized or diffuse strain during reorganization of the Pacific-North America plate boundary. Map-view translations of crustal blocks influence the relative motions of adjacent blocks, an approach adhered to in global plate-circuit models (Atwater and Stock, 1998; 2013). Thus, a synthesis of the magnitude and timing of horizontal strain across a broad zone of distributed deformation can provide insight into processes of strain partitioning and potential kinematic links between adjacent structural domains. Furthermore, it can help prioritize and guide future work by identifying gaps in our understanding of plate boundary deformation and provide a degree of predictability for palinspastic reconstructions in areas where little information exists. At present, detailed geologic studies of crustal deformation related to the Pacific-North America plate boundary in the LoCR region are limited, leading to considerable uncertainty in the late Cenozoic tectonic evolution of the region. This uncertainty limits our understanding of how plate coupling evolves during the transition from a convergent margin to a transform margin. In this paper, we utilize animated palinspastic fault-based reconstructions to evaluate the tectonic evolution of the LoCR region and to examine potential inconsistencies of the spatio-temporal evolution of the late Cenozoic Pacific-North America plate boundary. Based on revised palinspastic reconstructions and remaining inconsistencies, we hypothesize that (1) late Miocene transtensional faulting related to the Gulf of California shear zone and eastern California shear zone promoted tectonic subsidence in the LoCR region that permitted the subsequent southward lake spillover of the Colorado River and connection with the northern Gulf of California, (2) distributed Pliocene transtensional faulting likely occurred within the southern LoCR region, and is presently unaccounted for in most studies of geologic units related to the Pliocene Colorado River, and (3) the Chocolate Mountains anticlinorium can be reconstructed to a broadly linear, E-W-oriented structure at ca. 11 Ma, consistent with reconstruction of several other strain markers along the southern San Andreas Fault system.

Lower Colorado River↗
USGS2015

Preface

This book grew out of a topical session on “Central Virginia Earthquakes of 2011: Geology, Geophysics, and Significance for Seismic Hazards in Eastern North America” at the 2012 The Geological Society of America (GSA) Annual Meeting in Charlotte, North Carolina (USA). It also benefitted from related sessions at other meetings. The goal of this volume, The 2011 Mineral, Virginia, Earthquake, and Its Significance for Seismic Hazards in Eastern North America , is to bring together as much information as possible on lessons learned from this rare event. Chapters encompass a wide range of geoscience, engineering, and related studies of this earthquake and its effects from the epicentral area in central Virginia to Washington, D.C., and beyond. The intended audience is a broad spectrum of geoscientists, engineers, and decision makers interested in understanding earthquakes and seismic hazards in eastern North America and other intraplate settings. Chapters by Berti et al. (21), Chapman (2), Costain (8), Davenport et al. (15), Green et al. (9), Heller and Carter (10), Horton et al. (14), Hughes et al. (19), Powars et al. (23), Pratt et al. (16), Roeloffs et al. (7), Shah et al. (17), Stephenson et al. (3), Walsh et al. (18), and Wells et al. (12) are expansions of presentations at the 2012 GSA meeting. The volume also contains chapters from recent studies that were not presented at the GSA meeting, including those by Bobyarchick (22), Burton et al. (20), Dreiling and Mooney (5), Li et al. (11), McNamara et al. (4), Pollitz and Mooney (6), and Shahidi et al. (13). Following an overview and synthesis by the volume editors (1), chapters are arranged under the topical headings “Seismology and Regional Effects,” “Earthquake Damage, Geotechnical, and Engineering Investigations,” “Aftershocks, Geophysical Imaging, and Modeling,” “Geologic Investigations—Epicentral Area,” and “Geologic Investigations— Central Virginia Seismic Zone and Nearby Faults.” We thank the authors for their contributions and the many scientists and engineers who contributed time and expertise in reviewing manuscripts to substantially improve the quality of the volume. These reviewers include Gail Atkinson, Christopher Bailey, Richard Berquist, Kimberly Blisniuk, Paul Bodin, Aaron Bradshaw, Clive Collins, Ariel Conn, Randy Cox, Haitham Dawood, James Dewey, John Ebel, David Fenster, Alexander Gates, Kathleen Haller, Gregory Hancock, Robert Hatcher, William Henika, Paul Hsieh, Steven Jaumé, Jeffrey Kimball, Charles Langston, Jongwon Lee, Andrea Llenos, John McBride, Scott Olson, Michael Oskin, Brent Owens, Gilles Peltzer, Mark Quigley, Dhananjay Ravat, David Saftner, Arthur Snoke, Jamison Steidl, Kevin Stewart, Alice Stieve, Danielle Sumy, Ertugrul Taciroglu, Roy Van Arsdale, Mason Walters, Chiyuen Wang, Yang Wang, Richard Whittecar, Lorraine Wolf, Clint Wood, Liam Wotherspoon, and some anonymous reviewers.

Virginia↗
USGS2013

The regional forcing of Northern hemisphere drought during recent warm tropical west Pacific Ocean La Niña events

Northern Hemisphere circulations differ considerably between individual El Niño-Southern Oscillation events due to internal atmospheric variability and variation in the zonal location of sea surface temperature forcing over the tropical Pacific Ocean. This study examines the similarities between recent Northern Hemisphere droughts associated with La Niña events and anomalously warm tropical west Pacific sea surface temperatures during 1988–1989, 1998–2000, 2007–2008 and 2010–2011 in terms of the hemispheric-scale circulations and the regional forcing of precipitation over North America and Asia during the cold season of November through April. The continental precipitation reductions associated with recent central Pacific La Niña events were most severe over North America, eastern Africa, the Middle East and southwest Asia. High pressure dominated the entire Northern Hemisphere mid-latitudes and weakened and displaced storm tracks northward over North America into central Canada. Regionally over North America and Asia, the position of anomalous circulations within the zonal band of mid-latitude high pressure varied between each La Niña event. Over the northwestern and southeastern United States and southern Asia, the interactions of anomalous circulations resulted in consistent regional temperature advection, which was subsequently balanced by similar precipitation-modifying vertical motions. Over the central and northeastern United States, the spatial variation of anomalous circulations resulted in modest inter-seasonal temperature advection variations, which were balanced by varying vertical motion and precipitation patterns. Over the Middle East and eastern Africa, the divergence of moisture and the advection of dry air due to anomalous circulations enhanced each of the droughts.

Climate Dynamics↗
USGS2024

A systematic review of the effects of climate variability and change on black and brown bear ecology and interactions with humans

Climate change poses a pervasive threat to humans and wildlife by altering resource availability, changing co-occurrences, and directly or indirectly influencing human-wildlife interactions. For many wildlife agencies in North America, managing bears ( Ursus spp.) and human-bear interactions is a priority, yet the direct and indirect effects of climate change are exacerbating management challenges. Understanding the underlying ecological drivers of bear responses to climate variability and change, and the implications for conflict, will be critical for maintaining human-bear coexistence in North America. We synthesized 120 articles that identified direct and indirect mechanisms by which climate variability and change affect brown bears ( Ursus arctos ) and American black bears ( Ursus americanus ) in North America. The literature focused on examining climate impacts on bear diet, body size, habitat selection, space use, activity, denning chronology, and population demographics and dynamics. Across these categories, we summarized the documented and projected bear responses and resulting implications for human-bear interactions. Climate-driven changes in natural food availability were frequently implicated in influencing bear behavior and demography, and creating conditions under which interactions with humans are likely to increase. Bears in North America may face increased challenges as habitat and natural food availability continue to be altered by climate change. Our review provides a foundation upon which to identify climate drivers of bear ecology, conditions conducive to human-bear interactions, and adaptive management strategies. Given substantial evidence of climate impacts to bears, incorporating climate considerations into bear management can help managers strategically allocate resources and promote human-bear coexistence.

Biological Conservation↗
USGS2006

North American prairie wetlands are important nonforested land-based carbon storage sites

We evaluated the potential of prairie wetlands in North America as carbon sinks. Agricultural conversion has resulted in the average loss of 10.1 Mg ha- 1 of soil organic carbon on over 16 million ha of wetlands in this region. Wetland restoration has potential to sequester 378 Tg of organic carbon over a 10-year period. Wetlands can sequester over twice the organic carbon as no-till cropland on only about 17% of the total land area in the region. We estimate that wetland restoration has potential to offset 2.4% of the annual fossil CO2 emission reported for North America in 1990. ?? 2005 Elsevier B.V. All rights reserved.

Science of the Total Environment↗
USGS2024

Formation and evolution of the Pacific-North American (San Andreas) plate boundary: Constraints from the crustal architecture of northern California

The northward migration of the Mendocino triple junction (MTJ) drives a fundamental plate boundary transformation from convergence to translation; producing a series of strike-slip faults, that become the San Andreas plate boundary. We find that the 3-D structure of the Pacific plate lithosphere in the vicinity of the MTJ controls the location of San Andreas plate boundary formation. At the time of initiation of the Pacific-North America plate boundary (∼30 Ma), the sequential interaction with the western margin of North America of the Pioneer Fracture Zone, soon followed by the Mendocino Fracture Zone, led to the capture of a small segment of partially subducted Farallon lithosphere by the Pacific plate, termed the Pioneer Fragment (PF). Since that time, the PF has translated with the Pacific Plate along the western margin of North America. Recently developed, high-resolution seismic-tomographic imagery of northern California indicates that (a) the PF is extant, occupying the western half of the slab window, immediately south of the MTJ; (b) the eastern edge of the PF lies beneath the newly forming Maacama fault system, which develops to become the locus for the primary plate boundary structure after approximately 6–10 Ma; and (c) the location of the translating PF adjacent to the asthenosphere of the slab window generates a shear zone within and below the crust that develops into the plate boundary faults. As a result, the San Andreas plate boundary forms interior to the western margin of North America, rather than at its western edge.

California↗