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At least 919 records · Page 51Linked to original sources

USGS2022

Understanding rates of change: A case study using fossil pollen records from California to assess the potential for and challenges to a regional data synthesis

Insights into the rates at which ecosystems and vegetation respond to a changing climate is fundamental to anticipating impacts of projected climate change. Characterization of vegetation change over millennia to centuries has potential to make an important contribution toward this goal, and regional scale syntheses of fossil pollen data can provide the foundation for this understanding. However, challenges of data analysis and integration are nontrivial. Here we present a case study in which publicly available fossil pollen data for California are assessed and analyzed. The data are selected according to a clearly defined selection criteria, and a Rate of Change (RoC) value is calculated to assess rates of vegetation change in California from ~15k BP (before A.D. 1950) to the present. Our results highlight several challenges presented by the extant data sets, including temporal sampling variation within and between records, large age control uncertainties, and sparse, geographically biased coverage. Recommendations for methodological refinements to better characterize ecological rates of change include increasing sampling frequency, maintaining a consistent temporal spacing within records, and applying probabilistic approaches to existing pollen data sets.

California↗

USGS2017

The effect of Holocene temperature fluctuations on the evolution and ecology of Neotoma (woodrats) in Idaho and northwestern Utah

Animals respond to climatic change by adapting or by altering distributional patterns. How an animal responds is influenced by where it is positioned within its geographic range; the probability of extirpation is increased near range boundaries. Here, we examine the impact of Holocene climatic fluctuations on a small mammalian herbivore, the bushy-tailed woodrat (Neotoma cinerea), at five locations within south central Idaho and northwestern Utah. Previous work demonstrated that woodrats adapt to temperature shifts by altering body size. We focus here on the relationship between body mass, temperature, and location within the geographic range. Body mass is estimated by measuring fossil fecal pellets, a technique validated in earlier work. Overall, we find the predicted phenotypic response to climate change: Animals were larger during cold periods, and smaller during warmer episodes. However, we also identify several time periods when changes in environmental temperature exceeded the adaptive flexibility of N. cinerea. A smaller-bodied species, the desert woodrat (N. lepida) apparently invaded lower elevation sites during the mid-Holocene, despite being behaviorally and physically subordinate to N. cinerea. Analysis of contemporary patterns of body size and thermal tolerances for both woodrat species suggests this was because of the greater heat tolerance of N. lepida. The robust spatial relationship between contemporary body size and ambient temperature is used as a proxy to reconstruct local climate during the Holocene. ?? 2003 Elsevier Science (USA). All rights reserved.

Quaternary Research↗

USGS2024

Defining the hafnium isotopic signature of the Appalachian orogen through analysis of detrital zircons from modern fluvial sediments

Fluvial sediments are the product of erosion, weathering, and transport of bedrock within a well-defined catchment area, and their constituent grains may therefore record valuable information about the lithological and geochemical properties of geologic units within the upstream drainage. Analysis of U-Pb ages and Lu/Hf isotopic values in detrital zircon grains from major rivers in the eastern USA characterizes these parameters within broad areas of the Appalachian orogen. In this study, five modern fluvial sediment samples, collected across ~1500 km and representing 216,000 km2 of total catchment area, reveal that the relative proportions of Mesoproterozoic to Paleozoic U-Pb crystallization ages vary widely across the former Laurentian margin. However, εHft values in the same samples are largely consistent regardless of their geographic location. Mesoproterozoic (Grenville orogen) zircons display a more limited range of εHft values (approximately 0 to +10 εHft units) compared to the more negative, more variable values (-15 to +10) found in grains from the Paleozoic orogenies. When compared to other published modern detrital samples from the Gulf Coastal Plain, Appalachian samples show more similarity to each other and to the Pleistocene of Florida than to those from the Mississippi River mouth, likely because the latter also sources sediments from the Cordillera of western North America. More negative εHft values in Paleozoic zircons may be genetically related to older Mesoproterozoic grains, as they are compatible with the continued isotopic evolution of Lu/Hf derived from the mantle between 1.2 and 2.0 Ga. Hafnium geochemistry in detrital grains may therefore have some utility in discerning sediment provenance between the Appalachians and other regions, and may also provide useful information regarding the nature of crustal generation through time.

Journal of Geology↗

USGS2016

Genetic diversity of Wolbachia endosymbionts in Culex quinquefasciatus from Hawai`i, Midway Atoll, and Samoa

Incompatible insect techniques are potential methods for controlling Culex quinquefasciatus and avian disease transmission in Hawai‘i without the use of pesticides or genetically modified organisms. The approach is based on naturally occurring sperm-egg incompatibilities within the Culex pipiens complex that are controlled by different strains of the bacterial endosymbiont Wolbachia pipientis (wPip). Incompatibilities can be unidirectional (crosses between males infected with strain A and females infected with strain B are fertile, while reciprocal crosses are not) or bidirectional (reciprocal crosses between sexes with different wPip strains are infertile). The technique depends on release of sufficient numbers of male mosquitoes infected with an incompatible wPip strain to suppress mosquito populations and reduce transmission of introduced avian malaria ( Plasmodium relictum ) and Avipoxvirus in native forest bird habitats. Both diseases are difficult to manage using more traditional methods based on removal and treatment of larval habitats and coordination of multiple approaches may be needed to control this vector. We characterized the diversity of Wolbachia strains in C. quinquefasciatus from Hawai‘i, Kaua‘i, Midway Atoll, and American Samoa with a variety of genetic markers to identify compatibility groups and their distribution within and between islands. We confirmed the presence of wPip with multilocus sequence typing, tested for local genetic variability using 16 WO prophage genes, and identified similarities to strains from other parts of the world with a transposable element (tr1). We also tested for genetic differences in ankyrin motifs (ank2 and pk1) which have been used to classify wPip strains into five worldwide groups (wPip1–wPip5) that vary in compatibility with each other based on experimental crosses. We found a mixture of both widely distributed and site specific genotypes based on presence or absence of WO prophage and transposable element markers on Hawai‘i Island (Volcano, Pu‘u Wa‘awa‘a, Laupāhoehoe, Kaumana, Kahuku, Nīnole, and Maulua Gulch), Kaua‘i Island (Kawaikōī, Mōhihi, Kalāheo, Lāwa‘i and Hanapepe) and Midway Atoll. Genotypes from American Samoa were unique and formed their own clade. Based on analysis of ankyrin motifs, wPip strains from Hawai‘i, Kaua‘i, and Midway Atoll were most similar to wPip5 strains of Australasian origin. By contrast, Wolbachia strains from Culex quinquefasciatus collected in American Samoa were most similar to wPip3 strains of American origin. We detected a single Culex mosquito from Pu‘u Wa‘awa‘a on Hawai‘i Island that was infected with a unique wPip3 genotype. This discovery, plus a rarefaction analysis of genotypes from Kaua‘i and Hawai‘i Islands suggests that limited sampling may have underestimated diversity of wPip in our study. Mosquitoes infected with wPip5 and wPip3 are bidirectionally compatible with each other based on prior studies, which would support their ability to coexist within the same population on Hawai‘i Island. Available evidence from prior studies suggests that genotype wPip4 from Africa, the Middle East, Europe, and Asia is bidirectionally incompatible with genotype wPip5 and varies in compatibility with genotype wPip3 depending on geographic origin. Since wPip5 appears to be the most common compatibility group in Hawai‘i based on limited sampling, logical next steps are to 1) expand the current survey to include additional islands and localities, 2) infect a laboratory colony of Hawaiian Culex with wPip4 through tetracycline treatment of Hawaiian mosquitoes and backcross with Culex from Europe, North Africa, and the Middle East that are naturally infected with wPip4, 3) conduct cage trials to confirm bidirectional incompatibilities between Hawaiian Culex infected with wPip4 and wPip5, and 4) conduct field trials to evaluate whether release of incompatible males can be applied at small scales to suppress local populations.

American Samoa, Hawaii↗

USGS2023

Latency and geofence testing of wireless emergency alerts intended for the ShakeAlert® earthquake early warning system for the West Coast of the United States of America

ShakeAlert, the earthquake early warning (EEW) system for the West Coast of the United States, attempts to provides crucial warnings before strong shaking occurs. However, because the alerts are triggered only when an earthquake is already in progress, and the alert latencies and delivery times are platform dependent, the time between these warnings and the arrival of shaking is variable. The ShakeAlert system uses, among other public alerting platforms like a mobile phone operating system, smartphone apps, and the Federal Emergency Management Agency Integrated Public Alert & Warning System (IPAWS). IPAWS sends Wireless Emergency Alerts (WEAs) informing people via their smartphones and other mobile devices about various events, such as natural hazards, child abductions, or public health information about COVID-19. However, little is known about the IPAWS delivery latencies. Given that people may have only a few seconds of notice after they receive an alert to take a protective action before they feel earthquake shaking, quantifying latencies is critical to understanding whether the IPAWS system is useful for EEW. In this study, we developed new methods to test the IPAWS distribution system's performance, both with devices in a controlled environment and as well as with a 2019 community-based feedback form, in Oakland and San Diego County, California, respectively. The controlled environment test used mobile phones (including smart and non-smart phones) and associated devices to determine alert receipt times; the community research form had participants self-report their receipt times. By triangulating the data between the controlled test environment and the community research, we determined the latency statistics as well as whether the geofence (the geographic area where the alert was intended to be sent) held broadly. We found that the latencies were similar between the two tests despite the large differences in population sizes. WEA messages were received within a median time frame of 6–12 s, and the geofence held with only a few exceptions. We use this latency to assess how the system would have performed in two large earthquakes, the 1989 M6.9 Loma Prieta and 2019 M7.1 Ridgecrest earthquakes, which both occurred near our WEA test locations. Our analysis revealed that had IPAWS been available during those earthquakes, particularly Loma Prieta, it would have provided crucial seconds of notice that damaging shaking was imminent in some locations relatively far from the epicenter. Further, we find affordable non-smart phones can receive WEAs as fast as smartphones. Finally, our new method can be used for latency and geospatial testing going forward for IPAWS and other similar alerting systems.

California↗

USGS2006

Benthic foraminifera from a relict flood tidal delta along the Virginia/North Carolina Outer Banks

Examination of benthic foraminifera from six vibracores collected from a relict flood tidal delta near the Virginia/North Carolina border documents the assemblages associated with a former inlet and provides geologic evidence of this former inlet that once defined the boundary between Virginia and North Carolina along the Outer Banks. Three distinct foraminiferal assemblages were identified. The oldest assemblage contained abundant and diverse forms, dominated by Elphidium excavatum and several other calcareous species typical of shallow nearshore areas. Sediment immediately below and above this diverse calcareous assemblage was barren or nearly barren of foraminifera. A medium-salinity agglutinated marsh assemblage characterized mainly by Trochammina inflata with fewer Tiphotrocha comprimata overlies the uppermost barren unit. The core top assemblage was dominated by low-salinity marsh species Jadammina macrescens, Miliammina petila and Miliammina fusca. A comparison of these vertically-stacked assemblages with the modern geographic distribution of assemblages in the Outer Banks estuarine system and on the nearby continental shelf reveals a succession of depositional environments proceeding from estuarine and flood tidal delta to medium salinity marsh to lower salinity marsh. These changes in depositional environments reflect a rapid and dramatic increase in salinity caused by the opening of an inlet followed by a gradual decrease in salinity due to inlet shoaling and eventual marsh colonization of the flood tidal delta. These changes cannot be determined through sedimentological studies alone; micropaleontological analysis is required. We conclude this distinctive trend of changing depositional environments constitutes paleontological evidence of the origin and evolution of Old Currituck Inlet that breached the barrier spit prior to 1585AD, actively built a flood tidal delta for more than 145 years, and then closed in 1731AD allowing the flood tidal delta to become colonized by marsh species.

North Carolina, Virginia↗

USGS2015

Long-term effects of wildfire on greater sage-grouse - integrating population and ecosystem concepts for management in the Great Basin

Greater sage-grouse ( Centrocercus urophasianus ; hereinafter, sage-grouse) are a sagebrush obligate species that has declined concomitantly with the loss and fragmentation of sagebrush ecosystems across most of its geographical range. The species currently is listed as a candidate for federal protection under the Endangered Species Act (ESA). Increasing wildfire frequency and changing climate frequently are identified as two environmental drivers that contribute to the decline of sage-grouse populations, yet few studies have rigorously quantified their effects on sage-grouse populations across broad spatial scales and long time periods. To help inform a threat assessment within the Great Basin for listing sage-grouse in 2015 under the ESA, we conducted an extensive analysis of wildfire and climatic effects on sage-grouse population growth derived from 30 years of lek-count data collected across the hydrographic Great Basin of Western North America. Annual (1984–2013) patterns of wildfire were derived from an extensive dataset of remotely sensed 30-meter imagery and precipitation derived from locally downscaled spatially explicit data. In the sagebrush ecosystem, underlying soil conditions also contribute strongly to variation in resilience to disturbance and resistance to plant community changes (R&R). Thus, we developed predictions from models of post-wildfire recovery and chronic effects of wildfire based on three spatially explicit R&R classes derived from soil moisture and temperature regimes. We found evidence of an interaction between the effects of wildfire (chronically affected burned area within 5 kilometers of a lek) and climatic conditions (spring through fall precipitation) after accounting for a consistent density-dependent effect. Specifically, burned areas near leks nullifies population growth that normally follows years with relatively high precipitation. In models, this effect results in long-term population declines for sage-grouse despite cyclic periods of high precipitation. Based on 30-year projections of burn and recovery rates, our population model predicted steady and substantial long-term declines in population size across the Great Basin. Further, example management scenarios that may help offset adverse wildfire effects are provided by models of varying levels of fire suppression and post-wildfire restoration that focus on areas especially important to sage-grouse populations. These models illustrate how sage-grouse population persistence likely will be compromised as sagebrush ecosystems and sage-grouse habitat are degraded by wildfire, especially in a warmer and drier climate, and by invasion of annual grasses that can increase wildfire frequency and size in the Great Basin.

California, Idaho, Nevada, Oregon, Utah↗

USGS2025

Mapping potential sensitivity to hydrogeomorphic change in the UMRS riverscape

In 2020 the U.S. Geological Survey (USGS), as part of the Upper Mississippi River Restoration (UMRR) Program, began a new project to characterize potential hydrogeomorphic change associated with hydrogeomorphic units (HGUs) and their catenae (units linked by their association with sediment sources and flow origins). The goal of the project was to develop a geographic information system (GIS) database of HGUs for the Upper Mississippi River System (UMRS) available to both scientists and river managers working on UMRR studies and HREP planning and design studies. The characterization was based on a hydrogeomorphic change hierarchical classification developed previously for the UMRS. The products were generated with automated techniques in a GIS using systemic datasets. Landforms were mapped from the 2015 UMRS topobathymetric dataset with geomorphon (shape-based) tools tailored for the large riverscape, valley bottom environments in the UMRS. A clustering analysis was applied to the resulting landforms to identify HGUs associated with zones of perennial low flows, bankfull flows, and overbank floodplains. Catenae were assembled based on the proximity of the units to the main channel, tributary mouths, and side channels from previously published aquatic areas (USACE, 2018) coupled with least-cost flowpath linkages between potential sediment origins and planform change units developed by Rogala, Fitzpatrick, and Henderson (2020). These GIS-based analyses were successful at identifying a range of HGUs using an automated technique with available data across the entire riverscape, with emphasis on those that have the potential for hydrogeomorphic change. Most of the resulting features are depositional, as expected in a large river system. However, this is the first attempt of linking tributary inputs, side channel erosion and levee breaches with their depositional counterparts. The approach was successfully piloted in Pools 8 and 10 in the Upper Impounded Reach and Pool 14 in the Lower Impounded Reach, with next steps for application in reaches of the unimpounded section and Illinois River. This report emphasizes results from Pool 10, which was the focus of most of our attention during the pilot phase.

Illinois, Indiana, Iowa, Minnesota, Missouri, Sout↗

USGS2025

Alternating movement strategies of a tropical raptor

The majority of raptor species reside in the tropics, yet very little is known about their movement ecology. However, quantifying movement behavior can provide otherwise elusive information on resource needs, habitat selection, and ecological constraints, which is important for understanding ecological patterns and the management of species of conservation concern. On the Island of Hawai‘i, Hawai‘i, USA, the endemic ‘Io, or Hawaiian Hawk ( Buteo solitarius ), is a species of conservation concern that little is known of their movement ecology, yet they are dependent on a fragmented and rapidly changing environment. We tracked 15 individuals for up to 18 months across a diverse landscape on the eastern side of the island. We found that all ‘Io occupied a relatively small geographic area, their place of residency, where they spent all or most of their time. However, 10 individuals also exhibited an alternative movement pattern, where individuals repeatedly commuted back and forth between their place of residency to another, geographically disjunct location. These commuter periods, which could last from 24–180 days, were characterized by frequent (9–259) movements, with individual trips lasting 4–77 h away from their place of residency and 12–47 h in between commuter trips. In most cases, individuals went to the same non-contiguous commuting destination, even across multiple commuting sessions, indicating high fidelity to commuting locations. The ‘Io is a forest adapted Buteo but occurs across a diverse landscape from forest to agriculture lands to urban areas. Habitat selection analysis indicated high individual variation among different birds, but generally a preference for forest patches at localized levels. The discovery of the alternative commuting strategy for many ‘Io represents a cryptic movement pattern in the species, demonstrating the power of small, long-lived Global Position System tracking devices to track movement and providing important insights into the ecology of a tropical island raptor.

Hawaii↗

USGS2026

Genetic analysis of Harbison’s Dun Skipper to inform population management and restoration on conserved lands in San Diego County

This report details the development and analysis of single nucleotide polymorphic loci to understand population genetic structure and diversity among local populations of the Harbison’s dun skipper, Euphyes vestris harbisoni , primarily in San Diego County, California, USA. We developed a set of 2984 SNPs. Local populations were clustered into two to three regional genetic clusters throughout the San Diego County study area: a southeast cluster, an admixed northeast cluster, and a cluster comprised of the two local populations sampled west of Interstate 15 in Lake Hodges and Elfin Forest. Increasing genetic isolation with geographic distance was significant among local populations. While effective population size estimates calculated for the 2016 cohorts in the Southeast and Lake Hodges clusters were both high (point estimates above 500), individual heterozygosity appeared to decline in both clusters over time, and notably so in the Lake Hodges cluster after 2016, suggesting that this cluster may have lost genetic diversity over time. The Southeast cluster appears to have the highest observed heterozygosity across all surveyed areas, but sample sizes in the Northeast cluster were low which may affect these estimates. Future collection efforts may benefit from additional sampling in the Northeast cluster to improve representation. The management plan for Harbison’s dun skipper encourages restoration and re-establishment efforts in unoccupied or recently extirpated sites, particularly in the central portion of the range. Re-establishment efforts could target individuals from large and annually stable local populations in the Southeast portion of the range for transplant, as these populations were also the most genetically diverse.

California↗

USGS2024

Peak streamflow trends in Illinois and their relation to changes in climate, water years 1921–2020

This report characterizes changes in peak streamflow in Illinois and the relation of these changes to climatic variability, and provides a foundation for future studies that can address nonstationarity in peak-flow frequency analysis in Illinois. Records of annual peak and daily streamflow at streamgages and gridded monthly climatic data (observed and modeled) were examined across four trend periods (100 years, water years 1921–2020; 75 years, 1946–2020; 50 years, 1971–2020; 30 years 1991–2020) for trends, change points, and other statistical properties indicative of changing conditions. Median peak streamflows generally exhibit upward trends across the State for the 100- and 75-year trend periods and in northern and southern Illinois for the 50- and 30-year trend periods. The medians of the trend magnitudes (normalized by median peak streamflow) range from a 23-percent increase during the 30-year trend period to a 41-percent increase during the 100-year trend period. Streamgages with trends in peak streamflow often also have change points, or abrupt changes, in streamflow magnitude. More than two-thirds of streamgages at the 100- and 75-year trend periods exhibit a trend and change point in median peak streamflow in the same direction. Temporally, clusters of change points are observed in the late 1960s through early 1980s for the 100- and 75-year trend periods and around 2006 for the 50- and 30-year trend periods. Trends in the 90-percent quantile of peak streamflow, which correspond to the 10-percent exceedance probability often used for the design of drainage structures, increased about the same amount as the 50-percent quantile peak streamflows, except at the 100-year trend period, where the 50-percent quantile peak flow increased more for almost all streamgages. The frequency of high flows has also increased in Illinois, with increases in peaks-over-threshold observed across much of the State for the 100- and 75-year trend periods and in northern and southern Illinois for the 50- and 30-year trend periods. Upward trends in observed temperature and observed annual precipitation dominate in all trend periods, with clusters of likely upward trends observed in northern and southern Illinois at the 50- and 30-year trend periods. As expected in response to increasing temperature, the modeled proportion of precipitation falling as snow has largely decreased in the study basins across the State, and modeled potential evapotranspiration has increased. Upward trends in modeled annual runoff, which in this report incorporates only the effects of climatic variation, are observed in the same geographic areas where there are increases in observed annual precipitation. The widespread upward trends in the magnitude of median peak streamflows and the frequency with which high flows occur across the State at the 100- and 75-year trend periods and in northern and southern Illinois at the 50- and 30-year trend periods appear to be driven largely by increases in precipitation based on spatial patterns of these changes and statistical relations between streamflow and climate metrics. Other effects not considered in this report, like urbanization, may be important drivers for certain streamgages in the State. The prevalence of nonstationarity in peak streamflow in Illinois has important implications for peak-flow frequency analysis. Average annual precipitation and the occurrence of extreme precipitation events are expected to increase across the State. If precipitation continues to increase as expected, peak-flow frequency estimates based on older records may no longer represent the hydrologic regime of today, and methods for nonstationary peak-flow frequency analysis may be needed.

Illinois↗

USGS2005

Environmental contaminants and biomarker responses in fish from the Rio Grande and its U.S. tributaries: Spatial and temporal trends

We collected, examined, and analyzed 368 fish of seven species from 10 sites on rivers of the Rio Grande Basin (RGB) during late 1997 and early 1998 to document temporal and geographic trends in the concentrations of accumulative contaminants and to assess contaminant effects on the fish. Sites were located on the mainstem of the Rio Grande and on the Arroyo Colorado and Pecos River in Texas (TX), New Mexico (NM), and Colorado. Common carp (Cyprinus carpio) and largemouth bass (Micropterus salmoides) were the targeted species. Fish were examined in the field for internal and external visible gross lesions, selected organs were weighed to compute ponderal and organosomatic indices, and samples of tissues and fluids were obtained and preserved for analysis of fish health and reproductive biomarkers. Whole fish from each station were composited by species and gender and analyzed for organochlorine chemical residues and elemental contaminants using instrumental methods, and for 2,3,7,8-tetrachloro dibenzo-p-dioxin-like activity (TCDD-EQ) using the H4IIE rat hepatoma cell bioassay. Overall, fish from lower RGB stations contained greater concentrations of organochlorine pesticide residues and appeared to be less healthy than those from sites in the central and upper parts of the basin, as indicated by a general gradient of residue concentrations and biomarker responses. A minimal number of altered biomarkers and few or no elevated contaminant concentrations were noted in fish from the upper RGB. The exception was elevated concentrations [up to 0.46 ??g/g wet-weight (ww)] of total mercury (Hg) in predatory species from the Rio Grande at Elephant Butte Reservoir, NM, a condition documented in previous studies. Arsenic (As) and selenium (Se) concentrations were greatest in fish from sites in the central RGB; Se concentrations in fish from the Pecos River at Red Bluff Lake, TX and from the Rio Grande at Langtry, TX and Amistad International Reservoir, TX exceeded published fish and wildlife toxicity thresholds. In the lower RGB, residues of p,p???-DDT metabolites (???1.69 ??g/g ww), chlordane-related compounds (???0.21 ??g/g ww), dieldrin (???0.0.05 ??g/g ww), and toxaphene (???2.4 ??g/g ww) were detected in fish from most sites; maximum concentrations were in channel catfish (Ictalurus punctatus) from the Arroyo Colorado at Harlingen, TX. Concentrations of one or more residues exceeded toxicity thresholds for fish and wildlife in fish from this site and from the Rio Grande at Mission, TX and Brownsville, TX; however, concentrations were lower than those reported by previous studies. In addition, the proportional concentrations of p,p???-DDT at all sites were low, indicating weathered DDT rather than the influx of new material. Concentrations of total PCBs (<0.05 ??g/g ww) and TCDD-EQ (???6 pg/g ww) were comparatively low in all samples. Hepatic ethoxyresorufin O-deethylase (EROD) activity in some fish was elevated relative to reference rates at most sites, but was generally lower than previously reported activity in fish from heavily contaminated locations. The comparatively low PCB and TCDD-EQ concentrations together with elevated EROD activity may reflect exposure to polycyclic aromatic hydrocarbons. Reproductive biomarkers were consistent with chronic contaminant exposure at lower RGB sites; comparatively large percentages of intersex male largemouth bass, relatively low gonadosomatic indices, and elevated plasma vitellogenin concentrations in male fish were noted at three of the four stations. Large percentages of atretic eggs were also observed in the ovaries of female common carp from the Rio Grande at Brownsville, TX. Although many of the conditions noted may have other causes in addition to contaminant exposure, the biomarker results for the lower RGB sites are consistent with subtle responses of fish to contaminants, an interpretation supported by the chemical data of this and other investigations.

Science of the Total Environment↗

USGS2020

Automated extraction of areal extents for GNIS Summit features using the eminence core method

An important objective of the U.S. Geological Survey (USGS) is to enhance the Geographic Names Information System (GNIS) by automatically associating boundaries with terrain features that are currently spatially represented as two-dimensional points. In this paper, the discussion focuses on experiments for mapping GNIS Summit features using the eminence core region-growing method, which maps the area between a peak and its key col (saddle). A secondary goal of this project is to improve the positional accuracy of GNIS Summit features, since those locations were derived long ago and need to be snapped to local morphometric peaks detected from analysis of the highest-resolution digital elevation models (DEMs). The eminence cores delineated for a subset of GNIS Summit features were compared visually against basemaps and manually digitized polygons created by USGS staff. The comparisons revealed substantial differences between the computationally derived eminence cores and the manually generated polygons. Results clearly suggest that the default core delineation method tested must be modified to “roll back” or truncate growth of unreasonably large cores to smaller extents that would match people’s intuitive expectations. However, these results are far more encouraging than any method tested previously, since this method guarantees a 1-1 correspondence between polygons and GNIS Summit features.

Conference Paper↗

USGS2009

The National Map - geographic names

The Geographic Names Information System (GNIS), developed by the U.S. Geological Survey (USGS) in cooperation with the U.S. Board on Geographic Names (BGN), contains information about the official names for places, features, and areas in the 50 States, the District of Columbia, the territories and outlying areas of the United States, including Antarctica. It is the geographic names component of The National Map. The BGN maintains working relationships with State names authorities to cooperate in achieving the standardization of geographic names. The GNIS contains records on more than 2 million geographic names in the United States - from populated places, schools, reservoirs, and parks to streams, valleys, springs, ridges, and every feature type except roads and highways. Entries include information such as the federally-recognized name and variant names and spellings for the feature; former names; the status of the name as determined by the BGN; county or counties in which each named feature is located; geographic coordinates that locate the approximate center of an aerial feature or the mouth and source of a linear feature, such as a stream; name of the cell of the USGS topographic map or maps on which the feature may appear; elevation figures derived from the National Elevation Dataset; bibliographic code for the source of the name; BGN decision dates and historical information are available for some features. Data from the GNIS are used for emergency preparedness, mapmaking, local and regional planning, service delivery routing, marketing, site selection, environmental analysis, genealogical research, and other applications.

Fact Sheet↗

USGS1979

Regional flood-frequency relations for west-central Florida

This report presents regional relations for estimating the magnitude and frequency of floods on streams in west-central Florida. Flood prediction equations derived cover 20, 5-, 25-, 100-, 200-, and 500-year recurrence intervals. Annual floods for three geographic areas of west-central Florida were found to relate significantly to basin characteristics. Basin characteristics include drainage area, soils index, slope, and lake area. The average standard error of estimate for regional flood relations ranged from 38.4 to 52.1 percent with a mean of 43.5 percent. The average multiple correlation coefficient if 0.94. Regional relations apply to gaged and ungaged sites whose drainage areas are greater than 10 but less than 2,500 square miles. Tables of maximum known floods for 64 streamflow stations used in the analysis are included. Tables comparing station, weighted, and regional flood-peak discharges are also included. (Kosco-USGS)

Open-File Report↗

USGS2017

Inequity in ecosystem service delivery: Socioeconomic gaps in the public-private conservation network

Conservation areas, both public and private, are critical tools to protect biodiversity and deliver important ecosystem services (ES) to society. Although societal benefits from such ES are increasingly used to promote public support of conservation, the number of beneficiaries, their identity, and the magnitude of benefits are largely unknown for the vast majority of conservation areas in the United States public-private conservation network. The location of conservation areas in relation to people strongly influences the direction and magnitude of ES flows as well as the identity of beneficiaries. We analyzed benefit zones, the areas to which selected ES could be conveyed to beneficiaries, to assess who benefits from a typical conservation network. Better knowledge of ES flows and beneficiaries will help land conservationists make a stronger case for the broad collateral benefits of conservation and help to address issues of social-environmental justice. To evaluate who benefits the most from the current public-private conservation network, we delineated the benefit zones for local ES (within 16 km) that are conveyed along hydrological paths from public (federal and state) and private (easements) conservation lands in the states of North Carolina and Virginia, USA. We also discuss the challenges and demonstrate an approach for delineating nonhydrological benefits that are passively conveyed to beneficiaries. We mapped and compared the geographic distribution of benefit zones within and among conservation area types. We further compared beneficiary demographics across benefit zones of the conservation area types and found that hydrological benefit zones of federal protected areas encompass disproportionately fewer minority beneficiaries compared to statewide demographic patterns. In contrast, benefit zones of state protected areas and private easements encompassed a much greater proportion of minority beneficiaries (~22–25%). Benefit zones associated with private conservation lands included beneficiaries of significantly greater household income than benefit zones of other types of conservation areas. Our analysis of ES flows revealed significant socioeconomic gaps in how the current public-private conservation network benefits the public. These gaps warrant consideration in regional conservation plans and suggest that private conservation initiatives may be best suited for responding to the equity challenge. Enhancing the ecosystem benefits and the equity of benefit delivery from private conservation networks could build public and political support for long-term conservation strategies and ultimately enhance conservation efficacy.

North Carolina, Virginia↗

USGS2013

The North American Breeding Bird Survey 1966–2011: Summary analysis and species accounts

The North American Breeding Bird Survey is a roadside, count-based survey conducted by volunteer observers. Begun in 1966, it now is a primary source of information on spatial and temporal patterns of population change for North American birds. We analyze population change for states, provinces, Bird Conservation Regions, and the entire survey within the contiguous United States and southern Canada for 426 species using a hierarchical log-linear model that controls for observer effects in counting. We also map relative abundance and population change for each species using a spatial smoothing of data at the scale of survey routes. We present results in accounts that describe major breeding habitats, migratory status, conservation status, and population trends for each species at several geographic scales. We also present composite results for groups of species categorized by habitats and migratory status. The survey varies greatly among species in percentage of species' range covered and precision of results, but consistent patterns of decline occur among eastern forest, grassland, and aridland obligate birds while generalist bird species are increasing.

North American Fauna↗

USGS2018

The influence of sea level rise on the regional interdependence of coastal infrastructure

Sea level rise (SLR) is placing both immediate and long‐term pressures on coastal communities to take protective actions. Projects in the United States, and in many locations throughout the world, generally involve local jurisdictions raising the elevation of shoreline protection elements, with limited or no analysis of the feedback between shoreline management decisions and the impacts to water levels regionally. Our study examines the impact of local shoreline development on regional flood risk and considers SLR scenarios up to 1.5 m using a large‐scale numerical model, as an example, for San Francisco Bay. Here we show that measures to prevent flooding along an embayment shoreline in one location or subregion may increase inundation elsewhere in the system. The network of interactions occurs not only within subbasins of the Bay but also across the greater geographic extent from one end of the Bay to the other, and local jurisdiction may have either reciprocal relationships with or asymmetric impacts on one other. Importantly, the nature of the interaction network is seen to evolve with SLR: interactions are purely subregional at current sea level but with higher sea level (e.g., 1 m of SLR), not only do the subregional interdependencies strengthen but also regional interdependences emerge.

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