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USGS2006

Inventory of Amphibians and Reptiles at Manzanar National Historic Site, California

We conducted a baseline inventory for amphibians and reptiles at Manzanar National Historic Site (MANZ), Inyo County, California, in 2002-3. Objectives for this inventory were to: 1) inventory and document the occurrence of reptile and amphibian species at MANZ, with the goal of documenting at least 90% of the species present; 2) provide one voucher specimen for each species identified; 3) provide a GIS-referenced list of sensitive species that are known to be federally- or state-listed, rare, or worthy of special consideration that occur at MANZ; 4) describe park-wide distribution of federally- or state-listed, rare, or special concern species; 5) enter all species data into the National Park Service NPSpecies database; and 6) provide all deliverables as outlined in the Mojave Network Biological Inventory Study Plan. Survey methods included time-area constrained searches, lizard line transects, general surveys, nighttime road driving, and pitfall trapping. We documented the occurrence of ten reptile species (seven lizards and three snakes), but found no amphibians. Based on our findings, as well as literature review and searches for museum specimen records, we estimate inventory completeness for Manzanar to be 50%. Although the distribution and relative abundance of common lizard species is now known well enough to begin development of a monitoring protocol for that group, additional inventory work is needed in order to establish a baseline of species occurrence of amphibians and snakes at Manzanar. Key Words: amphibians, reptiles, Manzanar National Historic Site, Inyo County, California, Owens Valley, Mojave Desert, Great Basin Desert, inventory.

Open-File Report↗

USGS2006

Inventory of amphibians and reptiles at Death Valley National Park

As part of the National Park Service Inventory and Monitoring Program in the Mojave Network, we conducted an inventory of amphibians and reptiles at Death Valley National Park in 2002-04. Objectives for this inventory were to: 1) Inventory and document the occurrence of reptile and amphibian species occurring at DEVA, primarily within priority sampling areas, with the goal of documenting at least 90% of the species present; 2) document (through collection or museum specimen and literature review) one voucher specimen for each species identified; 3) provide a GIS-referenced list of sensitive species that are federally or state listed, rare, or worthy of special consideration that occur within priority sampling locations; 4) describe park-wide distribution of federally- or state-listed, rare, or special concern species; 5) enter all species data into the National Park Service NPSpecies database; and 6) provide all deliverables as outlined in the Mojave Network Biological Inventory Study Plan. Methods included daytime and nighttime visual encounter surveys, road driving, and pitfall trapping. Survey effort was concentrated in predetermined priority sampling areas, as well as in areas with a high potential for detecting undocumented species. We recorded 37 species during our surveys, including two species new to the park. During literature review and museum specimen database searches, we recorded three additional species from DEVA, elevating the documented species list to 40 (four amphibians and 36 reptiles). Based on our surveys, as well as literature and museum specimen review, we estimate an overall inventory completeness of 92% for Death Valley and an inventory completeness of 73% for amphibians and 95% for reptiles. Key Words: Amphibians, reptiles, Death Valley National Park, Inyo County, San Bernardino County, Esmeralda County, Nye County, California, Nevada, Mojave Desert, Great Basin Desert, inventory, NPSpecies.

Open-File Report↗

USGS2011

Comparative phylogeography of a coevolved community: Concerted population expansions in Joshua trees and four Yucca moths

Comparative phylogeographic studies have had mixed success in identifying common phylogeographic patterns among co-distributed organisms. Whereas some have found broadly similar patterns across a diverse array of taxa, others have found that the histories of different species are more idiosyncratic than congruent. The variation in the results of comparative phylogeographic studies could indicate that the extent to which sympatrically-distributed organisms share common biogeographic histories varies depending on the strength and specificity of ecological interactions between them. To test this hypothesis, we examined demographic and phylogeographic patterns in a highly specialized, coevolved community - Joshua trees (Yucca brevifolia) and their associated yucca moths. This tightly-integrated, mutually interdependent community is known to have experienced significant range changes at the end of the last glacial period, so there is a strong a priori expectation that these organisms will show common signatures of demographic and distributional changes over time. Using a database of >5000 GPS records for Joshua trees, and multi-locus DNA sequence data from the Joshua tree and four species of yucca moth, we combined paleaodistribution modeling with coalescent-based analyses of demographic and phylgeographic history. We extensively evaluated the power of our methods to infer past population size and distributional changes by evaluating the effect of different inference procedures on our results, comparing our palaeodistribution models to Pleistocene-aged packrat midden records, and simulating DNA sequence data under a variety of alternative demographic histories. Together the results indicate that these organisms have shared a common history of population expansion, and that these expansions were broadly coincident in time. However, contrary to our expectations, none of our analyses indicated significant range or population size reductions at the end of the last glacial period, and the inferred demographic changes substantially predate Holocene climate changes.

PLoS ONE↗

USGS2000

Seasonal distribution of bird populations at the Patuxent Research Refuge

A detailed study of seasonal changes in bird populationswas made at the Patuxent Research Refuge, located between Bowie and Laurel, Maryland during the years 1936-1949. The history of the Refuge is reviewed and its physical and biological characteristlcs summarized.. The methods of study used during the investigation mcluded: periodic censuses of a representative 304-acre study area over a two-year period; a census of the breeding population of the entire. Refuge during one year; detailed population studies of representative habitats during the breeding season; censuses of the wintering population of. the entire Refuge during two years; general surveys of wintering populations for seven years; and general observations of seasonal changes in bird populatlons over a fourteen-year period, including data from an extensive banding program and from many special types of censuses. The phenology of the Refuge is described in conslderable detail throughout the year, with special attention given to major fluctuatIons in bIrd populations as correlated with climatic changes and with seasonal aspectlon. of the vegetation. The component specIes of birds m the more important migration waves are listed. Figures approximating the Refuge breeding and wmtering populations are given, while indices representing the relative abundance of bird populations, based on figures from the two-year seasonal populatlon study, were obtained for the entire year. The greatest variety of species as well as the greatest number of individuals occurred on the Refuge during the migration .periods in spring and fall, the variety of species being slightly higher in spring than in fa!l, while the population of individuals was considerably higher in fall. Wmtering and breeding populations were low and relatively stable compared to the populations at other seasons.The ecological affinities of the bird populations differed greatly from one season to another. Species characteristic of edge habitats were much more numerous in winter, while forest species were predominant in summer. Insectivorous species comprised a large proportion (40 to 60 percent) of the total population during the warmer months, but were of minor importance in winter. The greatest number of species of birds on the Refuge occurred during the population peaks of insectivorous species, while the largest number of individuals was found during the population peaks of omnivorous and herbivorous species. The population peaks of insectivorous species were found to occur much later in spring and considerably earlier in fall than the. corresponding peaks of omnivorous and herbivorous species. The Fringillidae contributed the greatest number of individuals in winter, while the Parulidae was the most important family (numerically) in summer. Water birds and marsh birds were relatively unimportant throughout the year, due to the scarcity of suitable habitats. Permanent resident species were found to vary from about one-fifth to slightly less than one-half of the total population throughout the year, although many individuals of these species were either transients or part-time residents. Summer residents and winter residents were more abundant than permanent residents during their respective periods of occurrence. During the greater part of the migration period, transient species were found to comprise only 10 to 20 percent of the total population. transient individuals of all species would account for a much larger proportion of the population at this time. After comparing the results of these investigations with similar studies in other areas, it is believed that the seasonal population changes on the Patuxent Research Refuge are fairly representative of those occurring throughout the Middle Atlantic and East-central States. Yearly variations in seasonal population changes are described and the causative factors indicated, when known. Of these, food supply and weather conditions were generally the m

Society of Environmental Toxicology and Chemistry,↗

USGS1987

Introduction to the Special Issue on remote sensing

In 1977, the first Special Issue on remote sensing published by Geophysics contained papers selected from two special sessions at the 45th Annual International SEG Meeting, October 12–16, 1975, in Denver, Colorado. That first Special Issue consisted of eight papers: four are primarily tutorial (image processing, spectral signatures in the visible and near infrared, microwave spectra of layered media, and factor analysis of gamma-ray spectrometry), two involve structural interpretations with implications for mineral exploration and seismicity, and two examine multispectral reflectance data for detecting hydrothermal alteration and for uranium exploration. Although these papers indicate the importance of physical properties and models in the interpretation of remote sensing data, the studies were constrained by the instruments that collected the data and by the availability of image-processing software. Circumstances have changed significantly in the intervening decade, as illustrated in recent review papers (Watson, 1985; Goetz et al., 1983) and demonstrated by the papers in this Special Issue.

Geophysics↗

USGS2019

Movements of immature bald eagles: Implications for bird aircraft strike hazard

Bald eagle (Haliaeetus leucocephalus) aircraft strikes have increased dramatically over the last 20 years as their populations have recovered to near historic sizes. Their attraction to airfields and their large body size makes them a danger to aircraft and therefore important to airfield wildlife managers. However, their management is complicated by their special protected status and the iconic place they hold in the eyes of the public. To help airfield wildlife managers plan monitoring efforts and make informed management decisions, we studied the movements of 32 bald eagles telemetered as nestlings in the Chesapeake Bay of Virginia, USA. Managers often need to know when fledged eagles are most likely to move enough to encounter airfields near nests. As fledglings aged they moved progressively farther from the nest and spent more time away from the nest. Twenty-eight days after fledging, eagles spent most of the day (81±10%, 95% confidence interval) near the nest (<500 m) and only 7±7% of the daytime away from the nest (>1 km). By day 53 fledglings ventured beyond 2.5 km from the nest and spent 30 ± 15% the day >1 km away from their nest. However, distances moved were influenced by proximity of the nest to water, the quality and salinity of that water, and human population density. Eagles left their natal areas and generally migrated out of the Chesapeake Bay 60.5 ± 7.7 days (4 August) after fledging and returned to the Chesapeake Bay approximately 225 days later (March-April). Eighty-four percent (27 of 32) of the eagles that we tracked encountered 164 airfields across the east coast with 91% of those airfields located within 10 km of the Chesapeake Bay. Encounters with airfields outside the Chesapeake Bay occurred mainly during the first 1.5 years of life, peaking in late fall and early spring. Eagles were recorded on Chesapeake Bay airfields during each year, but encounters peaked in April of the first year of the bird’s life. This month coincides with the height of reported strikes of eagles by aircraft in the region. Our results suggest that eagles fledging from the Chesapeake Bay are not only an issue for airports near the Chesapeake Bay, but for airports across the east coast. Given the continued growth of the population, this issue is likely to continue and grow in significance.

Virginia↗

USGS2009

Estimating accuracy of land-cover composition from two-stage cluster sampling

Land-cover maps are often used to compute land-cover composition (i.e., the proportion or percent of area covered by each class), for each unit in a spatial partition of the region mapped. We derive design-based estimators of mean deviation (MD), mean absolute deviation (MAD), root mean square error (RMSE), and correlation (CORR) to quantify accuracy of land-cover composition for a general two-stage cluster sampling design, and for the special case of simple random sampling without replacement (SRSWOR) at each stage. The bias of the estimators for the two-stage SRSWOR design is evaluated via a simulation study. The estimators of RMSE and CORR have small bias except when sample size is small and the land-cover class is rare. The estimator of MAD is biased for both rare and common land-cover classes except when sample size is large. A general recommendation is that rare land-cover classes require large sample sizes to ensure that the accuracy estimators have small bias. ?? 2009 Elsevier Inc.

Remote Sensing of Environment↗

USGS2010

Estimating the breeding population of long-billed curlew in the United States

Determining population size and long-term trends in population size for species of high concern is a priority of international, national, and regional conservation plans. Long-billed curlews (Numenius americanus) are a species of special concern in North America due to apparent declines in their population. Because long-billed curlews are not adequately monitored by existing programs, we undertook a 2-year study with the goals of 1) determining present long-billed curlew distribution and breeding population size in the United States and 2) providing recommendations for a long-term long-billed curlew monitoring protocol. We selected a stratified random sample of survey routes in 16 western states for sampling in 2004 and 2005, and we analyzed count data from these routes to estimate detection probabilities and abundance. In addition, we evaluated habitat along roadsides to determine how well roadsides represented habitat throughout the sampling units. We estimated there were 164,515 (SE = 42,047) breeding long-billed curlews in 2004, and 109,533 (SE = 31,060) breeding individuals in 2005. These estimates far exceed currently accepted estimates based on expert opinion. We found that habitat along roadsides was representative of long-billed curlew habitat in general. We make recommendations for improving sampling methodology, and we present power curves to provide guidance on minimum sample sizes required to detect trends in abundance.

Journal of Wildlife Management↗

USGS2010

Evaluating abundance estimate precision and the assumptions of a count-based index for small mammals

Conservation and management of small mammals requires reliable knowledge of population size. We investigated precision of markrecapture and removal abundance estimates generated from live-trapping and snap-trapping data collected at sites on Guam (n 7), Rota (n 4), Saipan (n 5), and Tinian (n 3), in the Mariana Islands. We also evaluated a common index, captures per unit effort (CPUE), as a predictor of abundance. In addition, we evaluated cost and time associated with implementing live-trapping and snap-trapping and compared species-specific capture rates of selected live- and snap-traps. For all species, markrecapture estimates were consistently more precise than removal estimates based on coefficients of variation and 95 confidence intervals. The predictive utility of CPUE was poor but improved with increasing sampling duration. Nonetheless, modeling of sampling data revealed that underlying assumptions critical to application of an index of abundance, such as constant capture probability across space, time, and individuals, were not met. Although snap-trapping was cheaper and faster than live-trapping, the time difference was negligible when site preparation time was considered. Rattus diardii spp. captures were greatest in Haguruma live-traps (Standard Trading Co., Honolulu, HI) and Victor snap-traps (Woodstream Corporation, Lititz, PA), whereas Suncus murinus and Mus musculus captures were greatest in Sherman live-traps (H. B. Sherman Traps, Inc., Tallahassee, FL) and Museum Special snap-traps (Woodstream Corporation). Although snap-trapping and CPUE may have utility after validation against more rigorous methods, validation should occur across the full range of study conditions. Resources required for this level of validation would likely be better allocated towards implementing rigorous and robust methods.

Journal of Wildlife Management↗

USGS2026

Cenozoic distributed volcanism of the Arabia Plate—A review

Cenozoic volcanic rocks of the Arabia Plate cover about 140,000 square kilometers across a distance of about 3,000 kilometers from southern Yemen to southeastern Turkey. The majority of volcanic products are alkali basalts that erupted in restricted areas, commonly over periods of a million or more years, building mafic lava fields, each known in Arabic as a “harrat.” Harrat volcanism commenced following the Oligocene flood-lava effusions that blanketed the (now) Ethiopian highlands, southern Sudan, and western Yemen, and overlapped the latest Oligocene to early Miocene initial riftings of the Red Sea and Gulf of Aden, but the majority of harrat volcanism has been since approximately 13–10 million years ago. Persistent harrat magmatism in restricted locations led to the development of intermediate and evolved magmas (hawaiites, mugearites, benmoreites, trachytes, comendites, and phonolites) mainly through intracrustal crystallization-differentiation. Most of these intermediate and evolved magmas erupt at sites of the greatest aggregate volcanic relief, reflecting sites of the greatest overall magmatic fluxes. Production of fractionated magmas at these sites negates “monogenetic” as an appropriate descriptor of harrat volcanism. This chapter summarizes the geologic, eruptive, and tectonic history and aspects of the petrogenesis of the Cenozoic Arabian alkalic province. Particular emphasis is placed on results of a joint study of Ḩarrat Rahat adjacent to the city of Al Madīnah al Munawwarah, Kingdom of Saudi Arabia, published as U.S. Geological Survey Professional Paper 1862 and Saudi Geological Survey Special Report SGS–SP–2021–1. A goal of this chapter is to provide an introduction to those unfamiliar with this vast, enigmatic, and fascinating region of distributed continental volcanism.

Arabia Plate↗

USGS2010

Seabird databases and the new paradigm for scientific publication and attribution

For more than 300 years, the peer-reviewed journal article has been the principal medium for packaging and delivering scientific data. With new tools for managing digital data, a new paradigm is emerging—one that demands open and direct access to data and that enables and rewards a broad-based approach to scientific questions. Ground-breaking papers in the future will increasingly be those that creatively mine and synthesize vast stores of data available on the Internet. This is especially true for conservation science, in which essential data can be readily captured in standard record formats. For seabird professionals, a number of globally shared databases are in the offing, or should be. These databases will capture the salient results of inventories and monitoring, pelagic surveys, diet studies, and telemetry. A number of real or perceived barriers to data sharing exist, but none is insurmountable. Our discipline should take an important stride now by adopting a specially designed markup language for annotating and sharing seabird data.

Marine Ornithology: Journal of Seabird Research an↗

USGS2004

Water quality, hydrology, and the effects of changes in phosphorus loading to Pike Lake, Washington County, Wisconsin, with special emphasis on inlet-to-outlet short-circuiting

Pike Lake is a 459-acre, mesotrophic to eutrophic dimictic lake in southeastern Wisconsin. Because of concern over degrading water quality in the lake associated with further development in its watershed, a study was conducted by the U.S. Geological Survey from 1998 to 2000 to describe the water quality and hydrology of the lake, quantify sources of phosphorus including the effects of short-circuiting of inflows, and determine how changes in phosphorus loading should affect the water quality of the lake. Measuring all significant water and phosphorus sources and estimating lesser sources was the method used to construct detailed water and phosphorus budgets. The Rubicon River, ungaged near-lake surface inflow, precipitation, and ground water provide 55, 20, 17, and 7 percent of the total inflow, respectively. Water leaves the lake through the Rubicon River outlet (87 percent) or by evaporation (13 percent). Total input of phosphorus to the lake was about 3,500 pounds in 1999 and 2,400 pounds in 2000. About 80 percent of the phosphorus was from the Rubicon River, about half of which came from the watershed and half from a waste-water treatment plant in Slinger, Wisconsin. Inlet-to-outlet short-circuiting of phosphorus is facilitated by a meandering segment of the Rubicon River channel through a marsh at the north end of the lake. It is estimated that 77 percent of phosphorus from the Rubicon River in monitoring year 1999 and 65 percent in monitoring year 2000 was short-circuited to the outlet without entering the main body of the lake. Simulations using water-quality models within the Wisconsin Lake Model Suite (WiLMS) indicated Pike Lake's response to 13 different phosphorus-loading scenarios. These scenarios included a base 'normal' year (2000) for which lake water quality and loading were known, six different percentage increases or decreases in phosphorus loading from controllable sources, and six different loading scenarios corresponding to specific management actions. Model simulations indicate that a 50-percent reduction in controllable loading sources would be needed to achieve a mesotrophic classification with respect to phosphorus, chlorophyll a, and Secchi depth (an index of water clarity). Model simulations indicated that short-circuiting of phosphorus from the inlet to the outlet was the main reason the water quality of the lake is good relative to the amount of loading from the Rubicon River and that changes in the percentage of inlet-to-outlet short-circuiting have a significant influence on the water quality of the lake.

Wisconsin↗

USGS2015

Introduction to this special issue on ocean acidification: the pathway from science to policy

Ocean acidification (OA) is a progressive decrease in the pH of seawater over decades, caused primarily by uptake of excess atmospheric CO2 and accompanied by changes in seawater carbonate chemistry. Scientific studies designed to examine the effects of anthropogenic carbon dioxide (CO2) emissions on global carbon fluxes have also led to the detection of OA. During the last decade, this phenomenon has surged to the attention of not only scientists but also policymakers and the public. OA chemistry is well understood and follows first principles of acid-base chemistry (e.g., Gattuso and Hansson, 2011; Box 1 in McLaughlin et al.). Today, total anthropogenic release of CO2 exceeds nine petagrams of carbon annually, with ~85% coming directly from industrial sources and ~15% from changes in land use. The three major sinks for this CO2 are: ~46% of CO2 emitted remains in the atmosphere, ~29% is absorbed by the terrestrial biosphere, and the ocean absorbs the remaining ~26% (Le Quéré et al., 2014), resulting in OA. Since the Industrial Revolution, global average surface ocean pH has dropped 0.1 unit (about a 30% increase in acidity; IPCC, 2013), and it is expected to drop another 0.3 to 0.4 units by 2100 (100-150% increase in acidity) if CO2 emissions continue in a business-as-usual scenario (Orr et al., 2005; IPCC, 2013). Some areas of the ocean, such as coastal regions, upwelling zones, and polar seas, may be subjected to much greater chemical perturbations from OA than indicated by such globally averaged values (e.g., Feely et al., 2008; Mathis et al.).

Oceanography↗

USGS1959

History of Imuruk Lake, Seward Peninsula, Alaska

A study of Imuruk Lake, a large, shallow lake in north-central Seward Peninsula, Alaska, illuminates the climatic history of northwestern Alaska and the tectonic history of central Seward Peninsula during Pleistocene and Recent time. Special interest attaches to the older lake sediments, because they contain evidence concerning the climate, fauna, and flora that existed in the vicinity of Bering Strait at a time when the Bering land bridge was open and when animal and plant populations were being exchanged between the eastern and western hemispheres. The lake is 8 miles long and less than 10 feet deep; bottom sediments consisting of reworked wind-blown silt bury a rolling bedrock topography of much greater relief. Analysis of the hydrologic regime indicates that much of the water draining into the lake is lost by evaporation; smaller quantities are lost by discharge through the outlet, the Kugruk River, and by leakage into the lava flows along the lake shore. Changes in the duration and temperature of the summer ice-free season would result in changes in the amount of water lost by evaporation and thus in appreciable changes in lake level. Imuruk Lake occupies an initial low area on basaltic lava flows of Quaternary age, but the initial low area has been modified by faulting and now lies in a poorly defined graben. Topographic evidence confirmed by study of lacustrine terraces indicates that until recently Imuruk Lake drained westward into the Noxapaga River instead of eastward into the Kugruk River. A history of repeated warping of the lake basin, on which is superimposed a history of oscillating lake level which is due to changes in climate, is recorded by three systems of abandoned shore-line features found along the shores: a warped shore cliff of probable Illinoian age, a double set of warped terraces of probable Wisconsin age, and a low, horizontal terrace of Recent age. Bones of bison, horse, and mammoth were found in peaty sediments containing many twigs but no large wood; their presence indicates that these mammals, at least, were capable of surviving in a tundra environment during cold stages of the Pleistocene epoch and at a time when the Bering land bridge was in existence nearby. The sediments filling the deeper parts of the bedrock basin of Imuruk Lake probably contain an uninterrupted pollen record that reflects vegetation changes in central Seward Peninsula beginning in middle Illinoian time and terminating a few thousand years ago. Core drilling and pollen analysis of these sediments would greatly amplify our understanding of late Pleistocene events in the vicinity of the Bering land bridge.

Alaska↗

USGS2009

Ground-water quality data in the Owens and Indian Wells Valleys study unit, 2006: Results from the California GAMA Program

Ground-water quality in the approximately 1,630 square-mile Owens and Indian Wells Valleys study unit (OWENS) was investigated in September-December 2006 as part of the Priority Basin Project of Groundwater Ambient Monitoring and Assessment (GAMA) Program. The GAMA Priority Basin Project was developed in response to the Groundwater Quality Monitoring Act of 2001 and is being conducted by the U.S. Geological Survey (USGS) in collaboration with the California State Water Resources Control Board (SWRCB). The Owens and Indian Wells Valleys study was designed to provide a spatially unbiased assessment of raw ground-water quality within OWENS study unit, as well as a statistically consistent basis for comparing water quality throughout California. Samples were collected from 74 wells in Inyo, Kern, Mono, and San Bernardino Counties. Fifty-three of the wells were selected using a spatially distributed, randomized grid-based method to provide statistical representation of the study area (grid wells), and 21 wells were selected to evaluate changes in water chemistry in areas of interest (understanding wells). The ground-water samples were analyzed for a large number of synthetic organic constituents [volatile organic compounds (VOCs), pesticides and pesticide degradates, pharmaceutical compounds, and potential wastewater- indicator compounds], constituents of special interest [perchlorate, N-nitrosodimethylamine (NDMA), and 1,2,3- trichloropropane (1,2,3-TCP)], naturally occurring inorganic constituents [nutrients, major and minor ions, and trace elements], radioactive constituents, and microbial indicators. Naturally occurring isotopes [tritium, and carbon-14, and stable isotopes of hydrogen and oxygen in water], and dissolved noble gases also were measured to help identify the source and age of the sampled ground water. This study evaluated the quality of raw ground water in the aquifer in the OWENS study unit and did not attempt to evaluate the quality of treated water delivered to consumers. Water supplied to consumers typically is treated after withdrawal from the ground, disinfected, and blended with other waters to maintain acceptable water quality. Regulatory thresholds apply to treated water that is served to the consumer, not to raw ground water. However, to provide some context for the results, concentrations of constituents measured in the raw ground water were compared with regulatory and non-regulatory health-based thresholds established by the U.S. Environmental Protection Agency (USEPA) and California Department of Public Health (CDPH) and non-regulatory thresholds established for aesthetic concerns (secondary maximum contamination levels, SMCL-CA) by CDPH. VOCs and pesticides were detected in samples from less than one-third of the grid wells; all detections were below health-based thresholds, and most were less than one-one hundredth of threshold values. All detections of perchlorate and nutrients in samples from OWENS were below health-based thresholds. Most detections of trace elements in ground-water samples from OWENS wells were below health-based thresholds. In samples from the 53 grid wells, three constituents were detected at concentrations above USEPA maximum contaminant levels: arsenic in 5 samples, uranium in 4 samples, and fluoride in 1 sample. Two constituents were detected at concentrations above CDPH notification levels (boron in 9 samples and vanadium in 1 sample), and two were above USEPA lifetime health advisory levels (molybdenum in 3 samples and strontium in 1 sample). Most of the samples from OWENS wells had concentrations of major elements, TDS, and trace elements below the non-enforceable standards set for aesthetic concerns. Samples from nine grid wells had concentrations of manganese, iron, or TDS above the SMCL-CAs.

California↗

USGS1989

Processing and attenuation of noise in deep seismic-reflection data from the Gulf of Maine

The U.S. Geological Survey deep crustal studies reflection profile across the Gulf of Maine off southeastern New England was affected by three sources of noise: side-scattered noise, multiples, and 20-Hz whale sounds. The special processing most effective in minimizing this noise consisted of a combination of frequency-wavenumber (F-K) filtering, predictive deconvolution, and spectral whitening, each applied in the shot domain (prestack). Application of the F-K filter to remove side-scatter noise in the poststack domain resulted in a much poorer quality profile. The prestack noise suppression processing techniques resulted in a reflection profile with good signal-to-noise ratios and reliable strong reflections, especially at depths equivalent to the lower crust (24-34 km). Certain geologic features, such as a buried rift basin and a crustal fault are resolved much better within the upper crust after this processing. Finite difference migration of these data using realistic velocities produced excellent results. Migration was essential to distinguish between abundant dipping and subhorizontal reflections in the lower crust as well as to show an essentially transparent upper mantle. ?? 1989 Kluwer Academic Publishers.

Marine Geophysical Research↗

USGS2018

Stable isotope analysis enhances our understanding of diamondback terrapin Malaclemys terrapin foraging ecology

Dietary studies on generalist predators may provide valuable information on spatial or temporal changes in the structure of ecological communities. We initiated this study to provide baseline data and determine the utility of stable isotope analysis (SIA) to evaluate the foraging strategies of an opportunistic reptilian predator, the diamondback terrapin ( Malaclemys terrapin ), which specializes in salt marshes and mangrove estuaries along the Atlantic and Gulf coasts. We evaluated stable carbon (δ 13 C) and nitrogen (δ 15 N) isotope values of multiple tissues from terrapins inhabiting mainland and island mangrove habitats in south Florida and potential food sources to examine spatial and temporal variations in terrapin resource use. We fit linear regression models to determine the best predictors of isotopic values for both terrapins and their prey, and Stable Isotope Bayesian Ellipses in R (SIBER) analysis to examine terrapin isotopic niche space and overlap between groups. We identified differences in terrapin isotopic δ 13 C and δ 15 N values among all sites. Blood and scute tissues revealed different isotopic compositions and niche overlap between sites, suggesting diets or foraging locations may change over time, and amount of variation is site specific. Niche overlap between size classes was larger for blood (short term) versus scute (long term), suggesting greater variability in food habits or resource isotopes over the long term versus short term. These results demonstrate the usefulness of SIA in examining the spatial and temporal variability in diamondback terrapin resource use within estuary systems and further define their niche within these dynamic food webs.

Estuaries and Coasts↗

USGS2013

Sub-tidal benthic habitats of central San Francisco Bay and offshore Golden Gate area: A review

Deep-water potential estuarine and marine benthic habitat types were defined from a variety of new and interpreted data sets in central San Francisco Bay and offshore Golden Gate area including multibeam echosounder (MBES), side-scan sonar and bottom grab samples. Potential estuarine benthic habitats identiﬁed for the ﬁrst time range from hard bedrock outcrops on island and mainland ﬂanks and some Bay ﬂoor regions, to soft, very dynamic bedforms consisting of sediment waves and ripples. Soft sediment ranges from mud and sand to bimodal (two or more grain sizes) sediment of gravel, pebbles, and cobbles. In addition, considerable anthropogenic features (i.e., pipelines, bridge abutments, dredged channels, dump sites) were distinguished. Of the 52 potential benthic habitat types mapped (compressed to 14 types for this paper), 24 were of un-consolidated sediment with five of these comprised of dynamic bedforms or sediment waves and dunes, five of mixed (soft over hard) substrate type, six of hard substrate or rock outcrop, 13 of anthropogenically disturbed areas and four hard anthropogenic features. Rock outcrops and rubble are considered the primary habitat type for rockfish ( Sebastes spp. ), lingcod ( Ophiodon elongatus ) and in shallow water for herring ( Clupea pallasii ) spawning. Dynamic bedforms such as sand waves are considered potential foraging habitat for juvenile lingcod, may be sub-tidal habitat for the Paciﬁc sand lance ( Ammodytes hexapterus ) forage ﬁsh, and possibly resting habitat for migratory ﬁshes such as sturgeon ( Acipenser medirostris ). The potential marine benthic habitats identiﬁed in San Francisco Bay are not unlike those found in other estuaries around the world and this study should contribute signiﬁcant information that will be of interest to scientists, managers and ﬁshers investigating and utilizing bay and estuarine resources. As described in the many papers of this special issue, the understanding of the interrelationship of geology and ecology is critical to the identiﬁcation of essential habitats and the sustainability of a healthy ecosystem.

California↗