Search USGS⌕ Search

SEARCH · Search USGS

Results for “Nature Genetics”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 433 records · Page 24Linked to original sources
USGS2016

A moving target—incorporating knowledge of the spatial ecology of fish into the assessment and management of freshwater fish populations

Freshwater fish move vertically and horizontally through the aquatic landscape for a variety of reasons, such as to find and exploit patchy resources or to locate essential habitats (e.g., for spawning). Inherent challenges exist with the assessment of fish populations because they are moving targets. We submit that quantifying and describing the spatial ecology of fish and their habitat is an important component of freshwater fishery assessment and management. With a growing number of tools available for studying the spatial ecology of fishes (e.g., telemetry, population genetics, hydroacoustics, otolith microchemistry, stable isotope analysis), new knowledge can now be generated and incorporated into biological assessment and fishery management. For example, knowing when, where, and how to deploy assessment gears is essential to inform, refine, or calibrate assessment protocols. Such information is also useful for quantifying or avoiding bycatch of imperiled species. Knowledge of habitat connectivity and usage can identify critically important migration corridors and habitats and can be used to improve our understanding of variables that influence spatial structuring of fish populations. Similarly, demographic processes are partly driven by the behavior of fish and mediated by environmental drivers. Information on these processes is critical to the development and application of realistic population dynamics models. Collectively, biological assessment, when informed by knowledge of spatial ecology, can provide managers with the ability to understand how and when fish and their habitats may be exposed to different threats. Naturally, this knowledge helps to better evaluate or develop strategies to protect the long-term viability of fishery production. Failure to understand the spatial ecology of fishes and to incorporate spatiotemporal data can bias population assessments and forecasts and potentially lead to ineffective or counterproductive management actions.

Environmental Monitoring and Assessment↗
USGS2013

Network modularity reveals critical scales for connectivity in ecology and evolution

For nearly a century, biologists have emphasized the profound importance of spatial scale for ecology, evolution and conservation. Nonetheless, objectively identifying critical scales has proven incredibly challenging. Here we extend new techniques from physics and social sciences that estimate modularity on networks to identify critical scales for movement and gene flow in animals. Using four species that vary widely in dispersal ability and include both mark-recapture and population genetic data, we identify significant modularity in three species, two of which cannot be explained by geographic distance alone. Importantly, the inclusion of modularity in connectivity and population viability assessments alters conclusions regarding patch importance to connectivity and suggests higher metapopulation viability than when ignoring this hidden spatial scale. We argue that network modularity reveals critical meso-scales that are probably common in populations, providing a powerful means of identifying fundamental scales for biology and for conservation strategies aimed at recovering imperilled species.

Nature Communications↗
USGS2003

Arsenic in New England: Mineralogical and geochemical studies of sources and enrichment pathways

Detailed mineralogical, geochemical and radiogenic isotopic studies of iron-sulfide and secondary iron oxy-hydroxide minerals in natural bedrock in coastal Maine and New Hampshire test the link between arsenic-rich sulfide minerals in bedrock and secondary oxy-hydroxide minerals. Samples were selected from over 70 bedrock localities, including 22 within the regionally extensive and sulfide-mineral-rich Penobscot Formation and 10 associated with mineral deposits from coastal New Hampshire and Maine, and coupled with data from drill core collected at several sites including areas where well waters contain anomalous As abundances (e.g., Northport, ME). The data were used to establish a diversity of primary and secondary mineralogical hosts for arsenic in bedrock of this part of New England. The studies show that bedrock mineralogy is critical to contributing arsenic to groundwater and suggest a number of mineralogical pathways for arsenic that define weathering processes. The studies show that lead isotopic compositions of the sulfides and iron oxy-hydroxides overlap and establish a genetic link between the sulfides and secondary minerals. The data and interpretive results were presented at Arsenic in New England -- A multidisciplinary Scientific Conference, Manchester, New Hampshire, May 29-31, 2002, sponsored by the New Hampshire Consortium on Arsenic, are available in abstract and poster (full size = 84 by 36 inch sheet) formats.

Maine, New Hampshire↗
USGS2004

Mineral commodity profiles: nitrogen

Overview -- Nitrogen (N) is an essential element of life and a part of all animal and plant proteins. As a part of the DNA and RNA molecules, nitrogen is an essential constituent of each individual's genetic blueprint. As an essential element in the chlorophyll molecule, nitrogen is vital to a plant's ability to photosynthesize. Some crop plants, such as alfalfa, peas, peanuts, and soybeans, can convert atmospheric nitrogen into a usable form by a process referred to as 'fixation.' Most of the nitrogen that is available for crop production, however, comes from decomposing animal and plant waste or from commercially produced fertilizers. Commercial fertilizers contain nitrogen in the form of ammonium and/or nitrate or in a form that is quickly converted to the ammonium or nitrate form once the fertilizer is applied to the soil. Ammonia is generally the source of nitrogen in fertilizers. Anhydrous ammonia is commercially produced by reacting nitrogen with hydrogen under high temperatures and pressures. The source of nitrogen is the atmosphere, which is almost 80 percent nitrogen. Hydrogen is derived from a variety of raw materials, which include water, and crude oil, coal, and natural gas hydrocarbons. Nitrogen-based fertilizers are produced from ammonia feedstocks through a variety of chemical processes. Small quantities of nitrates are produced from mineral resources principally in Chile. In 2002, anhydrous ammonia and other nitrogen materials were produced in more than 70 countries. Global ammonia production was 108 million metric tons (Mt) of contained nitrogen. With 28 percent of this total, China was the largest producer of ammonia. Asia contributed 46 percent of total world ammonia production, and countries of the former U.S.S.R. represented 13 percent. North America also produced 13 percent of the total; Western Europe, 9 percent; the Middle East, 7 percent; Central America and South America, 5 percent; Eastern Europe, 3 percent; and Africa and Oceania contributed the remaining 4 percent (International Fertilizer Industry Association, 2003b, p. 1-4). In 2002, world ammonia exports were 13.1 Mt of contained nitrogen. Trinidad and Tobago (22 percent), Russia (18 percent), Ukraine (10 percent), and Indonesia (7 percent) accounted for 57 percent of the world total. The largest importing regions were North America with 36 percent of the total followed by Western Europe with 23 percent and Asia with 22 percent (International Fertilizer Industry Association, 2003b, p. 5L-11). In 2002, world urea production was 51.4 Mt of contained nitrogen, and exports were 12.0 Mt of contained nitrogen. China and India, which were the two largest producing countries, accounted for 48 percent of world production. The United States and Canada produced about 10 percent of the total. Russia and Ukraine together accounted for 28 percent of total urea exports; Central America and South America, 27 percent; and Asia, North America, and Western Europe, 10 percent each. North America accounted for 36 percent of the total urea imports; Western Europe, 23 percent; and Asia, 22 percent (International Fertilizer Industry Association, 2003f, p. 1-15). Ammonia production capacity in North America and Western Europe is projected to decline through 2004, and capacity in other world regions is projected to increase. Fluctuating natural gas prices are mainly responsible for the capacity decline in North America. Ammonia production capacity is continuing to shift to world regions that have abundant sources of natural gas, and away from those where costs (raw material, labor, environmental compliance) are higher.

Open-File Report↗
USGS1998

Molecular approaches to fish vaccines

For more than 50 years, researchers have tested a variety of killed, attenuated, and subunit preparations for control offish diseases. The earliest fish vaccines used killed preparations containing whole bacteria, viruses, or parasites and today, several bacterins have become commercially successful with more expected as improved delivery systems and adjuvants are realized. Live, attenuated vaccines have been developed by serial passage of a pathogen in culture or by using naturally occurring mutants and cross-reacting strains. These generally offer excellent protection and are cost-effective, but concerns about residual virulence or their effects on other aquatic species make them difficult candidates for licensing. In recent years, the tools of molecular biology have been applied to construction of a variety of recombinant, engineered, or subunit vaccines for fish. Among the approaches to be discussed are: attenuated strains of viruses and bacteria created by deletion of specific genes associated with virulence, in vitro synthesis of protective antigens from genes cloned into E. coli or baculovirus expression systems, chemical synthesis of peptides that represent protective epitopes, and direct immunization with DNA coding for protective antigens. Preparations representing each of these approaches have been tested in laboratory or field trials with various results and such vaccines promise to be safe and relatively inexpensive if they are able to provide protection when delivered by immersion. A significant advantage of genetically engineered vaccines is the ability to construct multivalent preparations that can protect fish against several pathogens or different strains of the same pathogen. While many of these novel vaccine strategies have been effective at stimulating specific immunity in the laboratory, more work is needed to develop better delivery systems and to overcome potential regulatory concerns.

Journal of Applied Ichthyology↗
USGS2022

Biofilms as potential reservoirs of stony coral tissue loss disease

Since 2014, corals throughout Florida’s Coral Reef have been plagued by an epizootic of unknown etiology, colloquially termed stony coral tissue loss disease (SCTLD). Although in Florida the movement of this waterborne coral disease has been consistent with natural transport via water currents, outbreaks in the Caribbean have been more sporadic, with infections occurring in locations inconsistent with spread via natural means. Often Caribbean outbreaks have been clustered near ports, potentially implicating ships as mediators of SCTLD into new regions. Biofilms attached to ship hulls, ballast tank walls, or other surfaces could represent a possible vector for the disease. We investigated whether bacteria shed by healthy and SCTLD-diseased corals would form distinct biofilms, and whether a SCTLD signal would be detectable within biofilm bacterial communities. Stainless steel plates serving as proxies for ship hulls, ballast tank walls, and other colonizable surfaces were incubated for three days in filtered seawater mesocosms containing healthy or SCTLD-infected corals. Resulting biofilm bacterial communities were characterized through sequencing of the V4 region of the 16S rRNA gene. We determined that bacteria shed by healthy and diseased corals formed significantly different biofilms consisting of highly diverse taxa. Comparison with 16S data from previous SCTLD investigations spanning different coral species, collection locations, years, and source material revealed the presence of numerous genetically identical sequences within the biofilm bacterial communities formed during exposure to SCTLD-infected corals, including several previously identified as possible SCTLD bioindicators. These results suggest ship-associated biofilms may have the potential to be vectors for the transmission of SCTLD into new regions.

Frontiers in Marine Science↗
USGS1996

Loess studies in central United States: Evolution of concepts

Few words in the realm of earth science have caused more debate than "loess". It is a common term that was first used as a name of a silt deposit before it was defined in a scientific sense. Because this "loose" deposit is easily distinguished from other more coherent deposits, it was recognized as a matter of practical concern and later became the object of much scientific scrutiny. Loess was first recognized along the Rhine Valley in Germany in the 1830s and was first noted in the United States in 1846 along the lower Mississippi River where it later became the center of attention. The use of the name eventually spread around the world, but its use has not been consistently applied. Over the years some interpretations and stratigraphic correlations have been validated, but others have been hotly contested on conceptual grounds and semantic issues. The concept of loess evolved into a complex issue as loess and loess-like deposits were discovered in different parts of the US. The evolution of concepts in the central US developed in four indefinite stages: the eras of (1) discovery and development of hypotheses, (2) conditional acceptance of the eolian origin of loess, (3) "bandwagon" popularity of loess research, and (4) analytical inquiry on the nature of loess. Toward the end of the first era around 1900, the popular opinion on the meaning of the term loess shifted from a lithological sense of loose silt to a lithogenetic sense of eolian silt. However, the dual use of the term fostered a lingering skepticism during the second era that ended in 1944 with an explosion of interest that lasted for more than a decade. In 1944, R.J. Russell proposed and H.N. Fisk defended a new non-eolian, property-based, concept of loess. The eolian advocates reacted with surprise and enthusiasm. Each side used constrained arguments to show their view of the problem, but did not examine the fundamental problem, which was not in the proofs of their hypothesis, but in the definition of the term. Between 1944 and about 1950, the debates about loess reached a maximum level of complexity. The main semantic problem was submersed in peripheral arguments about physical properties and genetic interpretations. The scholarly treatment of the subject by Fisk and Russell stimulated quality responses from a diversity of earth scientists interested in academic and applied studies, particularly geo-history, pedology, soil mechanics and stratigraphy. The long-lasting popularity of loess studies during the bandwagon era lasted to about 1970. By that time, the analytical and technical interests had attracted the mainstream into the fourth era with a focus beyond the old arguments. Although Fisk and Russell found themselves defending an unpopular theory, they stimulated a scientific interest in the late Quaternary history of the Mississippi Valley that may never be exceeded.

Engineering Geology↗
USGS2006

The toxicological geochemistry of Earth materials: An overview of processes and the interdisciplinary methods used to understand them

A broad spectrum of earth materials have been linked to, blamed for, and/or debated as sources for disease. In some cases, the links are clear. For example, excessive exposures to mineral dusts have long been recognized for their role in diseases such as: asbestosis, mesothelioma, and lung cancers (asbestos); silicosis and lung cancer (silica dusts); and coal-workers pneumoconiosis (coal dust). Lead poisoning, particularly in toddlers and young children, has been conclusively linked to involuntary ingestion of soils or other materials contaminated with lead-rich paint particles, leaded gasoline combustion byproducts, and some types of lead-rich mine wastes or smelter particulates. Waters with naturally elevated arsenic contents are common in many regions of the globe, and consumption of these waters has been documented as the source of arsenic-related diseases affecting thousands of people in south Asia and other regions. Exposure to dusts or soils containing pathogens has been documented as the cause of regionally common diseases such as valley fever (coccidioidomycosis) and much rarer diseases such as anthrax. Links between many other earth materials and specific diseases, although suspected, are less clear or are debated. For example, it has been suggested that geographic clusters of diseases such as leukemia are related to exposures to waters or atmospheric particulates containing organic or metal contaminants; however, for many clusters the exact causal relationships between disease and environmental exposure are difficult to prove conclusively. Even for many diseases in which the causal relationship is clear, such as in asbestosis and mesothelioma triggered by asbestos exposure, the minimum exposures needed to trigger disease, the influence of genetic factors, and the exact mechanisms of toxicity are still incompletely understood and are the focus of considerable debate within the public health community. Hence, understanding the health effects resulting from occupational and environmental exposures to a wide variety of earth materials remains a very active and fruitful area of research.

Reviews in Mineralogy and Geochemistry↗
USGS2026

Mountain goat declines in a protected, interior, native population

A shifting climate poses threats to alpine-adapted species including mountain goats. We used long-term (12 years) citizen science monitoring data and Bayesian N-mixture modeling to estimate population trends and drivers of population metrics among mountain goats in Glacier National Park (GNP). Median goats per site ( n = 37 sites) declined by 45% (95% credible interval [CRI] = 32%, 57%) from 77.8 (95% CRI = 64.4, 95.1) in 2008 to 42.3 (95% CRI = 34.3, 52.2) in 2019, with consistent declines from 2008 until 2015, when the number of estimated goats stabilized. The decline exceeds IUCN criteria for classifying a population as vulnerable, >30% declines over only two generations. Across years, relatively few goats occupied northwestern GNP. Goat numbers declined the most at northeastern sites, trended toward decline in most southern sites, and increased at only two west-central sites. The proportion of permanent snow and glaciers, the presence of natural mineral licks, and habituation strongly increased the initial abundance of goats in the area. Weather variables had the greatest influence on population growth rates, particularly precipitation between May 15 and June 15 of the previous summer, the neonatal period. Lower growth occurred with less snow water equivalent and lower mean winter temperature, early summer temperature, and early summer precipitation. Projected reductions of permanent snow, increasing spring and summer temperatures, and insufficient and variable spring precipitation raise concerns for the future of native goats in this region. Our analyses reveal ways to improve detection rates of goats during surveys, which is important for optimizing the precision of estimates and the power to detect future trends. Detection increased with goat habituation, retention of observers with experience, use of binoculars, and conducting surveys at lower temperatures and earlier dates. Improving detection will be particularly important given the lower number of goats currently observed in the park. Research to estimate park-wide population size, evaluate genetic structure and diversity, assess changing habitat, human recreation levels and forage, and forward-project climate effects on persistence will be crucial to understanding the context of these results and conserving this iconic, metapopulation at the southern edge of the distribution of native mountain goats.

Montana↗
USGS2014

River mainstem thermal regimes influence population structuring within an Appalachian brook trout population

Brook trout ( Salvelinus fontinalis ) often exist as highly differentiated populations, even at small spatial scales, due either to natural or anthropogenic sources of isolation and low rates of dispersal. In this study, we used molecular approaches to describe the unique population structure of brook trout inhabiting the Shavers Fork watershed, located in eastern West Virginia, and contrast it to nearby populations in tributaries of the upper Greenbrier River and North Fork South Branch Potomac Rivers. Bayesian and maximum likelihood clustering methods identified minimal population structuring among 14 collections of brook trout from throughout the mainstem and tributaries of Shavers Fork, highlighting the role of the cold-water mainstem for connectivity and high rates of effective migration among tributaries. In contrast, the Potomac and Greenbrier River collections displayed distinct levels of population differentiation among tributaries, presumably resulting from tributary isolation by warm-water mainstems. Our results highlight the importance of protecting and restoring cold-water mainstem habitats as part of region-wide brook trout conservation efforts. In addition, our results from Shavers Fork provide a contrast to previous genetic studies that characterize Appalachian brook trout as fragmented isolates rather than well-mixed populations. Additional study is needed to determine whether the existence of brook trout as genetically similar populations among tributaries is truly unique and whether connectivity among brook trout populations can potentially be restored within other central Appalachian watersheds.

West Virginia↗
USGS2011

A survey of microbial community diversity in marine sediments impacted by petroleum hydrocarbons from the Gulf of Mexico and Atlantic shorelines, Texas to Florida

Microbial community genomic DNA was extracted from sediment samples collected along the Gulf of Mexico and Atlantic coasts from Texas to Florida. Sample sites were identified as being ecologically sensitive and (or) as having high potential of being impacted by Macondo-1 (M-1) well oil from the Deepwater Horizon blowout. The diversity within the microbial communities associated with the collected sediments provides a baseline dataset to which microbial community-diversity data from impacted sites could be compared. To determine the microbial community diversity in the samples, genetic fingerprints were generated and compared. Specific sequences within the community genomic DNA were first amplified using the polymerase chain reaction (PCR) with a primer set that provides possible resolution to the species level. A second nested PCR was performed on the primary PCR products using a primer set on which a GC-clamp was attached to one of the primers. The nested PCR products were separated using denaturing-gradient gel electrophoresis (DGGE) that resolves the nested PCR products based on sequence dissimilarities (or similarities), forming a genomic fingerprint of the microbial diversity within the respective samples. Samples with similar fingerprints were grouped and compared to oil-fingerprint data from the same sites (Rosenbauer and others, 2011). The microbial community fingerprints were generally grouped into sites that had been shown to contain background concentrations of non-Deepwater Horizon oil. However, these groupings also included sites where no oil signature was detected. This report represents some of the first information on naturally occurring microbial communities in sediment from shorelines along the Gulf of Mexico and Atlantic coasts from Texas to Florida.

Gulf Of Mexico↗
USGS1951

Antimony ore in the Fairbanks district, Alaska

Antimony-bearing ores in the Fairbanks district, Alaska, are found principally in two areas, the extremities of which are at points 10 miles west and 23 miles northeast of Fairbanks; and one of two minor areas lies along this same trend 30 miles farther to the northeast. These areas are probably only local manifestations of mineralization that affected a much broader area and formed antimony-bearing deposits in neighboring districts, the closest of which is 50 miles away. The ores were exposed largely as a result of lode gold mining, but at two periods in the past, high prices for antimony ore warranted an independent production and about 2500 tons of stibnite ore was shipped. The sulfide deposits occupy the same fractures along which a gold-quartz mineralization of greater economic importance occurred; and both are probably genetically related to igneous rocks which intrude the schistose country rock. The sulfide is in part contemporaneous with some late-stage quartz in which it occurs as disseminated crystals; and in part the latest filling in the mineralized zones where it forms kidney-shaped masses of essentially solid sulfide. One extremely long mass must have contained nearly 100 tons of ore, but the average of the larger kidneys is closer to several tons. Much of the ore is stibnite, with quartz as a minor impurity, and assays show the tenor to vary from 40 to 65 percent antimony. Sulphantimonites are less abundant but likewise occur as disseminated crystals and as kidney-shaped bodies. Antimony oxides appear on the weathered surface and along fractures within the sulfide ore. Deposits containing either stibnite or sulphantimonite are known at more than 50 localities, but only eighteen have produced ore and the bulk of this came from the mines. The geology of the deposit, and the nature, extent, and period of the workings are covered in the detailed descriptions of individual occurrences. Several geologic and economic factors, which greatly affect prospecting and mining for stibnite ore in the area, are outlined. The principal available ore and reserves are considered to be ores earlier mined but never shipped, ore minable from near-surface deposits, and ores recoverable as a by-product of future gold mining. The outlook for stibnite production in the district is very uncertain. Apparently the greater portion of stibnite ore has already been recovered and present operations will strip the two principal areas of the district. This conclusion is based on the scanty discoveries since the last war and the fact that the areas are so pock-marked with prospects that there is little likelihood that any other large near-surface bodies remain to be discovered. Future prospecting would essentially be limited to attempts to seek the continuation of lodes previously having high yields of stibnite.

Open-File Report↗
USGS2017

Human interactions with sirenians (manatees and dugongs)

There are three extant sirenian species of the Trichechidae family and one living Dugongidae family member. Given their close ties to coastal and often urbanized habitats, sirenians are exposed to many types of anthropogenic activities that result in challenges to their well-being, poor health, and even death. In the wild, they are exposed to direct and indirect local pressures as well as subject to large-scale stressors such as global climate change acting on regions or entire genetic stocks. In captivity, they are subject to husbandry and management practices based on our collective knowledge, or in some cases lack thereof, of their needs and welfare. It is therefore reasonable to consider that their current imperiled status is very closely linked to our actions. In this chapter, we identify and define human interactions that may impact dugongs and manatees, including hunting, fisheries, boat interactions, negative interactions with man-made structures, disease and contaminants, and global climate change. We examine techniques used to investigate these impacts and the influence of sirenian biology and of changing human behaviors on potential outcomes. We examine how this differs for dugongs and manatees in the wild and for those held in captivity. Finally, we provide possible mitigation strategies and ways to assess the efforts we are making to improve the welfare of individuals and to conserve these species. This chapter identifies how the welfare of these species is intrinsically linked to the human interactions these animals experience, and how the nature of these interactions has changed with societal shifts. We proffer suggested ways to minimize negative impacts. Current knowledge should be used to minimize negative human interactions and impacts, to promote positive impacts, and to protect these animals for the future.

Book chapter↗
USGS2010

Distribution of the non-native gastropod Melanoides tuberculatus in Biscayne National Park, Florida

Introduction Melanoides tuberculatus (fig. 1), a gastropod that is not native to South Florida, was identified in Biscayne National Park (BNP) while researchers from the U.S. Geological Survey were conducting other studies around the Black Point canals in the summer of 2003. A study to determine the distribution, genetics, and salinity tolerance of this freshwater species began in 2004. For park managers and the recreational users of BNP, the presence of Melanoides tuberculatus is cause for concern because it is the intermediate host for several trematode parasites that affect humans and animals in multiple ways: Human health concerns include parasites (trematode worms) that affect the lung (Paragonimus westermani) and the liver ( Clonorchis sinensis , and Opisthorchis sp. ). Skin irritations and lesions can also be caused by trematodes that normally infect other species. Animal health concerns include parasites that affect the eyes of waterfowl ( Philophthalmus megalurus ), a trematode that burrows into the cartilage of fish and can lead to death ( Centrocestus formosanus ), and a trematode that infects the muscle tissue of fish and causes multiple abnormalities ( Haplorchis sp. ). When parasite-infected fish or crustaceans are eaten by birds or mammals, the next stage of the life cycle is in place (fig. 2). Native snail species concerns include the potential displacement of invertebrate species that make up the natural nearshore benthic communities in BNP. M. tuberculatus has very high reproductive rates, reproduces via parthenogenesis, and is live bearing, factors which increase the survivability of the offspring and increase competition for limited resources. These snails are considered to be freshwater animals in their native habitat of Southeast Asia. However, they have been collected in BNP in both estuarine and marine waters along the western margins of BNP and, as far as 1.7 kilometers (km) from shore at the Black Point canal inflow into Biscayne Bay (383 live per square meter (/m 2 ). In BNP, M. tuberculatus is a benthic inhabitant grazing on micro algal components at the sediment surface. A documented population with as many as 23,000/m 2 was observed at Snapper Creek, near Coral Gables, FL (Roessler and others, 1977), north of BNP.

Florida↗
USGS2022

Growth and survival rates of dispersing free embryos and settled larvae of pallid sturgeon (Scaphirhynchus albus) in the Missouri River, Montana and North Dakota

We released nearly 1.0 million 1-day post-hatch (dph) and 5-dph pallid sturgeon ( Scaphirhynchus albus ) free embryos in the Missouri River on 1 July 2019 and sequentially captured survivors at multiple sites through a 240-km river reach to quantify daily growth and survival rates during the early life stages. Genetic analysis was used to assign captured fish to released family lots and known ages. Growth rate was similar (0.74–0.75 mm day −1 ) between the 1- and 5-dph age groups during the 3–4-day dispersal period when water temperature averaged 16.8 °C. Daily survival rate was 0.64 during 1–4 dph for the original 1-dph age group and 0.80 during 5–7 dph for the original 5-dph age group. Total survival during free embryo dispersal (hatch to 9 dph) was estimated as 0.0437. The transition from dispersing as free embryos to settling as benthic larvae was verified for fish originally released as 5 dph. Growth of settled larvae was quantified with a Gompertz model through 75 dph (9 September; 112 mm) when water temperature was 18.8–21.0 °C in the rearing areas. Settled larvae had an estimated daily survival rate of 0.96, and estimated total survival during 9–75 dph was 0.0714. This study provides the first empirical survival estimates for pallid sturgeon early life stages in natural settings and is one of few studies reporting similar information for other sturgeon species. Applications of this work extend to pallid sturgeon restoration programs where population models are being developed to predict recruitment potential and population responses to river management alternatives.

Montana, North Dakota↗
USGS1983

Tin granites of Seward Peninsula, Alaska

Seven granite plutons, spatially and genetically related to tin metalization, are exposed in a 170-km-long belt across northwestern Seward Peninsula, Alaska. These plutons are cupolas and epizonal composite stocks that consist of several textural varieties of biotite granite, including medium- to coarse-grained seriate biotite granite, porphyritic biotite granite with an aplitic groundmass, and fine- to medium-grained equigranular biotite granite. The common accessory minerals are fluorite, allanite, apatite, and zircon. Other accessory minerals that are locally present include tourmaline, sphene, opaque oxide minerals, and late-forming (deuteric) muscovite and chlorite. The granites range in major-element contents as follows: SiO 2 , 72.5% to 76.6%; A1 2 O 3 , 12.7% to 14.3%; Na 2 O, 2.9% to 4.0%; K 2 O, 3.9% to 5.6%; and CaO, 0.6% to 1.2%. The sum of FeO + Fe 2 O 3 + MgO ranges from 0.3% to 2.4%; and the K 2 O to Na 2 O ratio from 1.1 to 1.8. The 0.1% to 0.9% F and 0.01% to 0.2% Cl reflect the over-all volatile-rich nature of the granites. The granites contain average or below-average concentrations of Co, Sc, Cr, and Zn, and generally above-average to distinctly high concentrations of Th, U, Hf, and Ta. The large cations emphasize the evolved nature of the granites; the Rb/Sr ratio is as high as 90 in some samples. Initial 87 Sr/ 86 Sr ratios range from 0.708 to as high as 0.720. The three Rb-Sr isochrons defined by the data agree with K-Ar age determinations and show that the stocks were emplaced during the Late Cretaceous, between about 70 and 80 m.y. ago. The field, petrologic, and geochemical data indicate that the plutons had a multistage origin that involved large-scale melting of sialic crust, emplacement of magmas derived from batholithic fractionation at depth, and subsequent evolution of these magmas to generate small volumes of more highly evolved residual magmas. Although evolution of the granite complexes was largely governed by crystal-melt fractionation, some minor-element variations in the highly evolved granites cannot be explained by this process. For example, the distribution of rubidium and the light rare-earths appears to have been influenced by volatile depletion at the final stages of crystallization. The field data, petrologic data, and variation trends, such as distinct shifts toward higher albite contents in the residual granites, suggest that the coexistence of a volatile phase was important in their evolution. These results require that models seeking to explain compositional gradients in high-level granite (rhyolite) systems fully consider the role of a coexisting volatile phase.

Alaska↗
USGS2015

Density, distribution, and genetic structure of grizzly bears in the Cabinet-Yaak Ecosystem

The conservation status of the 2 threatened grizzly bear ( Ursus arctos ) populations in the Cabinet-Yaak Ecosystem (CYE) of northern Montana and Idaho had remained unchanged since designation in 1975; however, the current demographic status of these populations was uncertain. No rigorous data on population density and distribution or analysis of recent population genetic structure were available to measure the effectiveness of conservation efforts. We used genetic detection data from hair corral, bear rub, and opportunistic sampling in traditional and spatial capture–recapture models to generate estimates of abundance and density of grizzly bears in the CYE. We calculated mean bear residency on our sampling grid from telemetry data using Huggins and Pledger models to estimate the average number of bears present and to correct our superpopulation estimates for lack of geographic closure. Estimated grizzly bear abundance (all sex and age classes) in the CYE in 2012 was 48–50 bears, approximately half the population recovery goal. Grizzly bear density in the CYE (4.3–4.5 grizzly bears/1,000 km 2 ) was among the lowest of interior North American populations. The sizes of the Cabinet ( n = 22–24) and Yaak ( n = 18–22) populations were similar. Spatial models produced similar estimates of abundance and density with comparable precision without requiring radio-telemetry data to address assumptions of geographic closure. The 2 populations in the CYE were demographically and reproductively isolated from each other and the Cabinet population was highly inbred. With parentage analysis, we documented natural migrants to the Cabinet and Yaak populations by bears born to parents in the Selkirk and Northern Continental Divide populations. These events supported data from other sources suggesting that the expansion of neighboring populations may eventually help sustain the CYE populations. However, the small size, isolation, and inbreeding documented by this study demonstrate the need for comprehensive management designed to support CYE population growth and increased connectivity and gene flow with other populations.

Idaho, Montana↗
USGS2025

Late Quaternary environmental change in eastern Beringia

Eastern Beringia (Alaska and western Yukon) is an extensive, high-latitude region of North America that remained largely unglaciated throughout the Quaternary. Consequently, its sedimentary deposits preserve long-term environmental records that have intrigued scientists for nearly a century. Recent advances in palaeoecological proxies and dating methods have proved critical in addressing long-standing questions about regional late Quaternary environmental change. At the same time, they have led to new and sometimes controversial hypotheses. This review covers recent discoveries and unresolved questions focused on the period 57,000–10,000 calendar years before C.E. 1950 (cal yr BP). The middle Wisconsin interstadial (57,000–30,000 cal yr BP) was a period of relative warmth in eastern Beringia, compared with the late Wisconsin (30,000–14,000 cal yr BP). Early in the interstadial occasional Picea woodland was present amongst widespread shrub tundra. Palaeoecological, sedimentary and isotopic data indicate that climate was cooler and drier than the Holocene, with high rates of aeolian activity. Megafauna typically associated with the ‘mammoth steppe’ ecosystem (woolly mammoth [ Mammuthus primigenius ], horse [ Equus ] and steppe-bison [ Bison priscus ]) were present in some abundance. The transition towards late Wisconsin cold-stage conditions (35,000–30,000 cal yr BP) coincided with the establishment of the Bering Land Bridge and featured expansion of spatially varied, herbaceous vegetation, sometimes associated with deep active layers. Sedimentary DNA ( seda DNA) and macrofossil evidence show vegetation was not a prairie-like grassland, and the term “steppe-tundra” is a better descriptor. Permafrost pore-ice isotopic (δ 18 O) records suggest a step change in one or more climate drivers ca. 30,000 cal yr BP, by which time steppe-tundra was established across eastern Beringia. It remains uncertain whether Picea survived cold-stage conditions within isolated refugia, or whether it recolonized from south of the Laurentide-Cordilleran ice sheets. Genetic data suggest that Picea probably survived in situ ; however, there is no definitive fossil evidence to support this. The end-Pleistocene transition from steppe-tundra to shrub tundra began ca. 15,000 cal yr BP and took place within decades at local scales. The expansion of woody taxa coincided with rising sea levels, reduced sea-ice extent and an abrupt shift in atmospheric circulation that enhanced precipitation. During this time, Earth's orbital configuration caused high early-summer temperatures and strong seasonality, creating growing conditions very different from today. The vegetation consisted of Salix and Betula shrub tundra with open areas of herbs and graminoids. During the deglacial warming trend, the Younger Dryas oscillation (12,800–11,700 cal yr BP) was variably expressed. It is generally evident in records affected by adjacent oceans but can be absent at sites in continental areas. These past conditions and paleoenvironmental changes have implications for contemporary issues: hypotheses about Pleistocene mammalian extinction; sensitivity of eastern Beringia to major oceanic reorganizations and high-frequency climate variability; the nature of woody plant expansion with climate warming; grazing, hydroclimate and fire as controls over ecosystems; the efficacy of “Pleistocene rewilding” for carbon capture.

Beringia↗