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USGS2006

Characteristics of a ringtail (Bassariscus astutus) population in Trans Pecos, Texas

Despite the common occurrence of ringtails (Bassariscus astutus) few studies have been conducted to assess population characteristics. The objectives of this study were to determine (1) habitat selection, (2) home range, (3) denning characteristics, and (4) food habits of ringtails in the Trans Pecos region of west Texas. Seventeen ringtails were captured between November 1999 and January 2001 using Havahart live box traps. Second- and third-order habitat selection was determined for a ringtail population using range sites, slope, elevation, and vegetation communities. Diets were determined from volumetric scat analysis. The mean summer and winter range sizes (100% Minimum Convex Polygon [MCP]) for ringtails (n = 5) were 0.28 ?? 0.163 km2 and 0.63 ?? 0.219 km2, respectively. Overlap between ringtail ranges averaged 33.3%. Ringtails preferred catclaw (Mimosa biuncifera), persimmon (Diospyros texana), oak (Quercus sp.) bottom and catclaw/goldeneye (Viguiera stenoloba), sideoats (Bouteloua curtipendula) slope communities. Rock dens were used exclusively by ringtails, with 80.6% of dens found on slopes between 30-60%. Plant (seeds and miscellaneous vegetation) and animal material were found in 74.6 and 86.6% of scats, respectively. Findings suggest that ringtails in Trans Pecos, Texas, are an important component of the ecosystem and that management practices should conserve canyon habitats and adjacent slopes for ringtails.

Texas Journal of Science↗

USGS1977

Organochlorine pesticide and polychlorinated biphenyl residues in selected fauna from a New Jersey salt marsh--1967 vs. 1973

More than a half million pounds of DDT were applied to control mosquitoes in salt marsh estuaries of Cape May County, New Jersey, from 1946 to 1966. The use of DDT was discontinued in the County after 1966. In 1967, mean concentrations of DDT and metabolites ranged from 0.63 to 9.05 ppm in aquatic fauna, but by 1973 mean residue levels had decreased 84 to 99 percent among nine species. DDE was still present at reduced levels in nearly all samples in 1973, but other DDT isomers had mostly disappeared. Dieldrin was detected only in clapper rails, and residue levels decreased during the period. Mean concentrations of PCB's increased in the clapper rail, remained the same in the fiddler crab and mud snail, and decreased in the sheepshead minnow, mummichog, striped killifish, and salt marsh snail. Small amounts of mirex, toxaphene, cis-chlordane (and/or trans-nonachlor), oxychlordane, and HCB were detected in a few specimens.

Pesticides Monitoring Journal↗

USGS2020

Temporal and spatial variability of shallow soil moisture across four planar hillslopes on a tropical ocean island, San Cristóbal, Galápagos

Study Region: This paper provides a summary of findings from temporal and spatial studies of soil water content on planar hillslopes across the equatorial island of San Cristóbal, Galápagos (Ecuador). Study Focus: Soil water content (SWC) was measured to generate temporal and spatial records to determine seasonal variation and to investigate how the behavior of surface and near-surface root-zone soil water may support island-wide hydrogeology models. SWC probes were installed at four weather stations in a climosequence to generate a temporal record and spatial surveys of shallow SWC across the selected sites were completed during wet and dry seasons. Temporal differences in SWC were driven by seasonal variations in rainfall and evapotranspiration, while spatial variability remained high during both wet and dry seasons. Unsaturated hydraulic conductivity determined by mini-disk infiltrometers was highly variable across the slopes, as were other hydrologic variables. New Hydrological Insights for the Region: The high heterogeneity of soil water and hydrologic characteristics provides a means to explain why little runoff is observed at the study sites: soils do not saturate uniformly across hillslopes, allowing for runoff generated in one part of the hillslope to be conducted into the soil in adjacent parts of the hillslope. The lack of connected surface runoff helps explain how water enters the groundwater system of the island.

Journal of Hydrology: Regional Studies↗

USGS2017

A refined electrofishing technique for collecting Silver Carp: Implications for management

Detecting nuisance species at low abundance or in newly established areas is critical to developing pest management strategies. Due to their sensitivity to disturbance and erratic jumping behavior, Silver Carp Hypophthalmichthys molitrix can be difficult to collect with traditional sampling methods. We compared catch per unit effort (CPUE) of all species from a Long Term Resource Monitoring (LTRM) electrofishing protocol to an experimental electrofishing technique designed to minimize Silver Carp evasion through tactical boat maneuvering and selective application of power. Differences in CPUE between electrofishing methods were detected for 2 of 41 species collected across 2 years of sampling at 20 sites along the Illinois River. The mean catch rate of Silver Carp using the experimental technique was 2.2 times the mean catch rate of the LTRM electrofishing technique; the increased capture efficiency at low relative abundance emphasizes the utility of this method for early detection. The experimental electrofishing also collected slightly larger Silver Carp (mean: 510.7 mm TL versus 495.2 mm TL), and nearly four times as many Silver Carp independently jumped into the boat during experimental transects. Novel sampling approaches, such as the experimental electrofishing technique used in this study, should be considered to increase probability of detection for aquatic nuisance species.

North American Journal of Fisheries Management↗

USGS2013

Roost selection by western long-eared myotis (Myotis evotis) in burned and unburned piñon–juniper woodlands of southwestern Colorado

All 16 species of bats known to occur in western Colorado are found at Mesa Verde National Park (MVNP) in the southwestern United States. Since 1996, wildfires have burned more than 70% of MVNP (> 15,000 ha), potentially altering food and roosting resources for bats. During the summers of 2006–2007, we investigated roost use by reproductive female western long-eared myotis ( Myotis evotis ). We located 33 bat roosts in rock crevices and 1 in a juniper snag. All but 2 of the roosts were in unburned habitat. Bats roosted alone or in small groups (≤3 individuals) and switched roosts frequently (1–7 roosts per bat, median = 1.5 roosts per bat, SE = 0.5 roosts per bat). We compared occupied roosts with randomly selected unoccupied crevices and used an information theoretic approach to determine which variables were most important in determining roost use at microhabitat and landscape scales. At the microhabitat scale, maternity roosts were higher above the ground and deeper than random, unoccupied rock crevices. At the landscape scale, roosts were closer to water and farther from burned habitat than random crevices, providing reproductive female M. evotis with the best opportunities to drink and forage for insects. Tree roosts are apparently not a vital resource for reproductive female M. evotis during the summer months at our study site, presumably because of the extensive availability of rock crevices. Understanding site-specific roosting behavior is important for proper management of bat populations because differences can exist between geographic regions, even among areas with similar plant communities.

Colorado↗

USGS2013

Estimating suitable environments for invasive plant species across large landscapes: a remote sensing strategy using Landsat 7 ETM+

The key to reducing ecological and economic damage caused by invasive plant species is to locate and eradicate new invasions before they threaten native biodiversity and ecological processes. We used Landsat Enhanced Thematic Mapper Plus imagery to estimate suitable environments for four invasive plants in Big Bend National Park, southwest Texas, using a presence-only modeling approach. Giant reed ( Arundo donax ), Lehmann lovegrass ( Eragrostis lehmanniana ), horehound ( Marrubium vulgare ) and buffelgrass ( Pennisteum ciliare ) were selected for remote sensing spatial analyses. Multiple dates/seasons of imagery were used to account for habitat conditions within the study area and to capture phenological differences among targeted species and the surrounding landscape. Individual species models had high (0.91 to 0.99) discriminative ability to differentiate invasive plant suitable environments from random background locations. Average test area under the receiver operating characteristic curve (AUC) ranged from 0.91 to 0.99, indicating that plant predictive models exhibited high discriminative ability to differentiate suitable environments for invasive plant species from random locations. Omission rates ranged from <1.0 to 18%. We demonstrated that useful models estimating suitable environments for invasive plants may be created with <50 occurrence locations and that reliable modeling using presence-only datasets can be powerful tools for land managers.

Texas↗

USGS2019

Freezing resistance, safety margins, and survival vary among big sagebrush populations across the western United States

Premise Physiological responses to temperature extremes are considered strong drivers of species’ demographic responses to climate variability. Plants are typically classified as either avoiders or tolerators in their freezing‐resistance mechanism, but a gradient of physiological‐threshold freezing responses may exist among individuals of a species. Moreover, adaptive significance of physiological freezing responses is poorly characterized, particularly under warming conditions that relax selection on cold hardiness. Methods Freezing responses were measured in winter and again for new foliage in spring for 14 populations of Artemisia tridentata collected throughout its range and planted in a warm common garden. The relationships of the freezing responses to survival were evaluated in the warm garden and in two colder gardens. Results Winter and spring freezing resistance were not correlated and appeared to be under differing selection regimes, as evident in correlations with different population climate of origin variables. All populations resisted considerably lower temperatures in winter than in spring, with populations from more continental climates showing narrower freezing safety margins (difference in temperatures at which ice‐nucleation occurs and 50% reduction in chlorophyll fluorescence occurs) in spring. Populations with greater winter freezing resistance had lower survivorship in the warmest garden, while populations with greater spring freezing resistance had lower survivorship in a colder garden. Conclusions These survivorship patterns relative to physiological thresholds suggest excess freezing resistance may incur a survival cost that likely relates to a trade‐off between carbon gain and freezing resistance during critical periods of moisture availability. This cost has implications for seed moved from cooler to warmer environments and for plants growing in warming environments.

American Journal of Botany↗

USGS2021

Larval Coregonus spp. diets and zooplankton community patterns in the Apostle Islands, Lake Superior

With the exception of lake whitefish ( Coregonus clupeaformis ), relatively little is known about the early life history of larval coregonines in the Laurentian Great Lakes. For example, our knowledge of the feeding ecology of larval coregonines (excluding lake whitefish) is based on only 900 stomachs reported in the literature. Here, we describe the diets and demographics of larval coregonines from ice-out to late July, and the contemporaneous zooplankton community, in the Apostle Islands region of Lake Superior in 2018. Exogenous feeding was evident among the smallest larvae (down to 6 mm). Percent of larvae with food in their stomachs increased and yolk reserves decreased as larvae grew from 10 to 13 mm. A majority of the diet (58%) was copepod nauplii, with generally positive selection for adult copepods and Holopedium . The patterns in exogenous feeding and yolk sac absorption were similar to observations in Lake Superior in the 1970s. Diets were also generally similar, although Limnocalanus , Holopedium , and zooplankton eggs were more prevalent in 2018 than the 1970s. Demographic data suggested at least two distinct cohorts and/or coregonine species in 2018. Post-hoc genetic testing of larvae in a parallel study suggested our samples comprised a mix of predominantly cisco ( C. artedi ), kiyi ( C. kiyi ), and bloater ( C. hoyi ). Early life history studies, when coupled with emerging genetic techniques that can identify larval coregonines to species, will provide a powerful combination to better understand population dynamics of coregonines at a time of ongoing restoration and rehabilitation efforts throughout the Great Lakes.

Apostle Islands, Lake Superior↗

USGS2000

Sequential dome-collapse nuées ardentes analyzed from broadband seismic data, Merapi Volcano, Indonesia

During the sequential dome collapse of Merapi Volcano on 22 November 1994, a broadband seismic station on the western slope was the only operational seismic equipment that provided continuous on-scale recording of the event. According to visual and seismic observations, the collapse activity lasted about 10 h. We divide the activity into two phases: (I) a period with fluctuating but generally increasing seismic activity associated with 24 moderate to large dome-collapse nuées ardentes, lasting about 40 min and culminating with the largest event at 10:54 (all times reported as local time); and (II) activity from 11:42 until 20:00 described by scattered clusters of individual rockfalls and 20 nuées ardentes. The broadband data were evaluated using the assumption that avalanches with the same source areas and descent paths exhibit a linear relation between source volume and recorded seismic-amplitude envelope area. A result of the analysis is the determination of the volume of selected individual events. From the field surveys, the total volume of the collapsed dome lava is 2.6 Mm 3 . Discounting the volumetric influence of rockfalls, the average size of the 44 nuées ardentes is therefore about 60,000 m 3 . The largest collapse event at 10:54 is estimated to involve 260,000 m 3 , based on an analysis of the seismicity. The remaining 23 phase I events averaged 60,000 m 3 , with the total volume of all phase I events accounting for 63% of the unstable dome. The 20 phase II events comprised 37% of the total volume and averaged 47,000 m 3 . The methods described here can be put to practical use in real-time monitoring situations. Broadband data were essential in this study primarily because of the wide dynamic range.

Journal of Volcanology and Geothermal Research↗

USGS1996

Feeding ecology of larval and juvenile American shad (Alosa sapidissima) in a small pond

Release ponds are used as part of a multifacet effort to restore American shad ( Alosa sapidissima ) in the upper Susquehanna River basin. Little information exists, however, on the feeding ecology of young shad in small ponds. Consequently, we examined feeding ecology and prey selection of 299 larval and 299 juvenile American shad in a small pond during spring and summer. Larval shad mainly consumed copepods (37.7%) and cladocerans (37.4%) whereas juvenile shad ate chironomids (43.1%) and ostracods (28.4%). Larval and juvenile shad exhibited diel variation in diet composition and feeding periodicity. Food consumption by shad was minimal at night; feeding activity was highest during the day, peaking at 2000 h for both larvae and juveniles. Electivity values of shad larvae for prey taxa were highest for cladocerans (+0.27) and lowest for ostracods (−0.07). Electivity values of juvenile shad were highest for chironomids (+ 0.21) and ostracods (+ 0.09), and lowest for copepods (− 0.08) and baetids (− 0.14). Our data indicate differences in diet composition, prey preference and, to a lesser extent, feeding patterns between larval and juvenile American shad in small pond environments.

Journal of Applied Ichthyology↗

USGS1982

Movements and wetland selection by brood-rearing black ducks

Movements and wetland selection by brood-rearing black ducks ( Anas rubripes ) were studied in Maine during 1977-80. Eight radio-marked hens moved their broods an average of 1.2 km from the nest to rearing pond, but only 1 hen initiated secondary brood movements. Half of the 85 broods reared in the study area used only 3 wetlands, and most rearing ponds contained active beaver ( Castor canadensis ) colonies. Brood-rearing hens preferred Emergent ponds over lakes and Evergreen Scrub-Shrub wetlands, and did not occupy Dead Scrub-Shrub, Unconsolidated Bottom, or Aquatic Bed wetlands. Rearing ponds were large and possessed extensive areas of flooded mountain alder ( Alnus incana ), willow ( Salix spp.), and herbaceous vegetation. Wetlands avoided by brood-rearing hens were those with large areas of open water, submergent aquatics, or ericaceous shrub vegetation.

Maine↗

USGS1997

Occurrence and flux of selected pesticides in surface water of the upper snake River Basin, Idaho and western Wyoming

During May and June 1994, 37 water samples were collected at 31 sites in the upper Snake River Basin and analyzed for 83 pesticides and pesticide metabolites. EPTC, atrazine, and the atrazine metabolite deethylated atrazine were the most frequently detected and were found in 30, 20, and 13 of the samples, respectively. Fifteen additional pesticides were detected at least once. All the compounds detected were at concentrations of less than 1 microgram per liter. Total annual applications of EPTC and atrazine within subbasins and their instantaneous instream fluxes have a logarithmic relation with coefficients of determination (R2 values) of 0.55 and 0.62, respectively. At the time of sampling, the median daily flux of EPTC was about O. 0001% of the annual amount applied in a subbasin, whereas the median daily flux of atrazine was between 0.001 and 0.01%. The difference in fluxes between EPTC and atrazine probably results from differences in their physical properties and in the method and timing of application.

Journal of Soil and Water Conservation↗

USGS2006

Inferences about winter temperatures and summer rains from the late Quaternary record of C 4 perennial grasses and C 3 desert shrubs in the northern Chihuahuan Desert

Late Quaternary histories of two North American desert biomes—C 4 grasslands and C 3 shrublands—are poorly known despite their sensitivity and potential value in reconstructing summer rains and winter temperatures. Plant macrofossil assemblages from packrat midden series in the northern Chihuahuan Desert show that C 4 grasses and annuals typical of desert grassland persisted near their present northern limits throughout the last glacial-interglacial cycle. By contrast, key C 3 desert shrubs appeared somewhat abruptly after 5000cal.yrBP. Bioclimatic envelopes for select C 4 and C 3 species are mapped to interpret the glacial-interglacial persistence of desert grassland and the mid-to-late Holocene expansion of desert shrublands. The envelopes suggest relatively warm Pleistocene temperatures with moist summers allowed for persistence of C 4 grasses, whereas winters were probably too cold (or too wet) for C 3 desert shrubs. Contrary to climate model results, core processes associated with the North American Monsoon and moisture transport to the northern Chihuahuan Desert remained intact throughout the last glacial-interglacial cycle. Mid-latitude effects, however, truncated midsummer (July-August) moisture transport north of 35° N. The sudden expansion of desert shrublands after 5000cal.yrBP may be a threshold response to warmer winters associated with increasing boreal winter insolation, and enhanced El Niño-Southern Oscillation variability.

Arizona, New Mexico, Texas↗

USGS1991

An analytical method for hydrogeochemical surveys: Inductively coupled plasma-atomic emission spectrometry after using enrichment coprecipitation with cobalt and ammonium pyrrolidine dithiocarbamate

Trace metals that are commonly associated with mineralization were concentrated and separated from natural water by coprecipitation with ammonium pyrollidine dithiocarbamate (APDC) and cobalt and determined by inductively coupled plasma-atomic emission spectroscopy (ICP-AES). The method is useful in hydrogeochemical surveys because it permits preconcentration near the sample sites, and selected metals are preserved shortly after the samples are collected. The procedure is relatively simple: (1) a liter of water is filtered; (2) the pH is adjusted; (3) Co chloride and APDC are added to coprecipitate the trace metals; and (4) later, the precipitate is filtered, dissolved, and diluted to 10 ml for a 100-fold concentration enrichment of the separated metals. Sb(III), As(III), Cd, Cr, Cu, Fe, Pb, Mo, Ni, Ag, V, and Zn can then be determined simultaneously by ICP-AES. In an experiment designed to measure the coprecipitation efficiency, Sb(III), Cd and Ag were recovered at 70 to 75% of their original concentration. The remaining metals were recovered at 85 to 100% of their original concentrations, however. The range for the lower limits of determination for the metals after preconcentration is 0.1 to 3.0 μg/l.

Journal of Geochemical Exploration↗

USGS2025

The ghost plume phenomenon and its impact on zenith-facing remote sensing measurements of volcanic SO2 emission rates

A large source of error in SO 2 emission rates derived from mobile Differential Optical Absorption Spectroscopy (DOAS) of volcanic gas plumes is the uncertainty in atmospheric light paths between the sun and the instrument, particularly under non-ideal atmospheric conditions, such as the presence of low clouds. DOAS instruments measure the SO 2 column density along the effective light path, so changes to that pathway directly affect the measured SO 2 signal. Due to complex radiative transfer mechanisms when a cloud is between the DOAS viewing position and a volcanic plume, measured plumes can appear spatially offset from their true location, a phenomenon informally referred to as “ghost plumes.” In addition to the appearance of ghost plumes, DOAS measurements recorded in non-ideal conditions have poorly characterized errors and are often discarded, limiting the data available to characterize volcanic degassing. In this study we simulate the radiative transfer associated with zenith-facing mobile DOAS traverses using the McArtim radiative transfer model for scenarios when there is a cloud layer between the instrument and the volcanic plume. In total, 217 permutations of atmospheric optical conditions are considered with varying cloud opacities (AOD = 0, 1, 2, 4, 8, 20), plume opacities (AOD = 0, 1, 2, 4, 8), solar zenith angles (SZA = 1°, 30°, 60°), and cloud thicknesses (200, 400, 800 m). We first develop objective criteria for selecting SO 2 baseline absorption levels and plume spatial extents. The simulated plume traverses are then integrated to obtain the SO 2 cross-sectional burdens which, after multiplication with the wind speed, yield SO 2 emission rates. We find large modification in the shape of the modeled cross-sectional burdens even under translucent (low AOD) cloud conditions in our modeled scenarios. Despite modification of the plume shape, the presence of a low cloud layer is typically not a large source of error in the SO 2 cross-sectional burden or emission rate obtained from zenith-facing DOAS traverses. We find that all measured cross-sectional burdens simulated using an aerosol-free plume in the above conditions and SZA ≤ 30° are within ±25% of the true value.

Journal of Volcanology and Goethermal Research↗

USGS2021

Performance of bedload sediment transport formulas applied to the Lower Minnesota River

Despite limitations in reproducing complex bedload sediment transport processes in rivers, formulas have been preferred over collection and analysis of field data due to the high cost and time-consuming nature of bedload discharge measurements. However, the performance of such formulas depends on the hydraulic and sedimentological conditions they attempt to describe. The availability of field measurements provides a unique opportunity to test bedload transport formulas to better guide formula selection. Hydraulic parameters and bedload discharge data from the Lower Minnesota River and two of its tributaries were used to evaluate nine bedload transport formulas using three different indices. The bedload data for the different sites were collected by the United States Geological Survey (USGS) from 2011 through 2014, with bed material varying from very coarse to medium sand. The formulas calculated higher bedload rates than were measured due to a combination of site-specific physical characteristics, including the presence of bed forms (dunes), and sampling uncertainties. Because of the lack of reproducibility of the tested formulas, five power functions, based on the relation between the specific unit power (independent hydraulic variable) and the USGS measured data (dependent variable), were derived as provisional equations to estimate the bedload discharge on the Lower Minnesota River and tributaries.

Minnesota↗

USGS1996

Predation by sea lamprey (Petromyzon marinus) on lake trout (Salvelinus namaycush) in southern Lake Ontario, 1982-1992

Dead lake trout ( Salvelinus namaycush ) killed by sea lamprey (P etromyzon marinus ) were collected from the bottom of Lake Ontario using bottom trawls. The number of dead lake trout per hectare could be predicted from the number of type A-1 sea lamprey marks observed on live fish in September gillnet surveys ( r 2 = 0.60, P < 0.01) but not from the sum of marks of types A-1, A-2, and A-3 combined. Sea lamprey selectively attacked and killed the largest lake trout. The lengths and ages of live fish with A-1 marks increased as the population of longer, older lake trout in the lake increased, and the length distributions of fish killed by sea lamprey were not different ( P > 0.05) from those of live fish with A-1 marks in 5 of 6 years where comparisons could be made. Compared with Lake Superior strain lake trout, Seneca Lake strain fish were only 0.41 times as likely to be attacked by sea lamprey and were less likely to die from an attack (both differences P < 0.05). Conservative estimates of the numbers of lake trout killed by sea lamprey in southern Lake Ontario from October to mid-November ranged from 17,000 in 1988 to 121,000 in 1984.

New York, Ontario↗

USGS2024

Male lake char release taurocholic acid as part of a mating pheromone

The evolutionary origins of sexual preferences for chemical signals remain poorly understood, due, in part, to scant information on the molecules involved. In the current study, we identified a male pheromone in lake char ( Salvelinus namaycush ) to evaluate the hypothesis that it exploits a non-sexual preference for juvenile odour. In anadromous char species, the odour of stream-resident juveniles guides migratory adults into spawning streams. Lake char are also attracted to juvenile odour but have lost the anadromous phenotype and spawn on nearshore reefs, where juvenile odour does not persist long enough to act as a cue for spawning site selection by adults. Previous behavioural data raised the possibility that males release a pheromone that includes components of juvenile odour. Using metabolomics, we found that the most abundant molecule released by males was also released by juveniles but not females. Tandem mass spectrometry and nuclear magnetic resonance were used to identify the molecule as taurocholic acid (TCA), which was previously implicated as a component of juvenile odour. Additional chemical analyses revealed that males release TCA at high rates via their urine during the spawning season. Finally, picomolar concentrations of TCA attracted pre-spawning and spawning females but not males. Taken together, our results indicate that male lake char release TCA as a mating pheromone and support the hypothesis that the pheromone is a partial match of juvenile odour.

Journal of Experimental Biology↗