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At least 541 records · Page 30Linked to original sources
USGS2009

Compositions of modern dust and surface sediments in the Desert Southwest, United States

Modern dusts across southwestern United States deserts are compositionally similar to dust-rich Av soil horizons (depths of 0-0.5 cm and 1-4 cm at 35 sites) for common crustal elements but distinctly different for some trace elements. Chemical compositions and magnetic properties of the soil samples are similar among sites relative to dust sources, geographic areas, and lithologic substrates. Exceptions are Li, U, and W, enriched in Owens Valley, California, and Mg and Sr, enriched in soils formed on calcareous fan gravel in southeast Nevada. The Av horizons are dominated by dust and reflect limited mixing with substrate sediments. Modern dust samples are also similar across the region, except that Owens Valley dusts are higher in Mg, Ba, and Li and dusts both there and at sites to the north on volcanic substrates are higher in Sb and W. Thus, dust and Av horizons consist of contributions from many different sources that are well mixed before deposition. Modern dusts contain significantly greater amounts of As, Cd, Cr, Cu, Ni, Pb, and Sb than do Av horizons, which record dust additions over hundreds to thousands of years. These results suggest that modern dust compositions are influenced by anthropogenic sources and emissions from Owens (dry) Lake after its artificial desiccation in 1926. Both modern dusts and Av horizons are enriched in As, Ba, Cu, Li, Sb, Th, U, and W relative to average crustal composition, which we interpret to indicate that the geologic sources of dust in the southwestern United States are geochemically distinctive.

Journal of Geophysical Research F: Earth Surface↗
USGS2015

Origins of geothermal gases at Yellowstone

Gas emissions at the Yellowstone Plateau Volcanic Field (YPVF) reflect open-system mixing of gas species originating from diverse rock types, magmas, and crustal fluids, all combined in varying proportions at different thermal areas. Gases are not necessarily in chemical equilibrium with the waters through which they vent, especially in acid sulfate terrain where bubbles stream through stagnant acid water. Gases in adjacent thermal areas often can be differentiated by isotopic and gas ratios, and cannot be tied to one another solely by shallow processes such as boiling-induced fractionation of a parent liquid. Instead, they inherit unique gas ratios (e.g., CH 4 /He) from the dominant rock reservoirs where they originate, some of which underlie the Quaternary volcanic rocks. Steam/gas ratios (essentially H 2 O/CO 2 ) of Yellowstone fumaroles correlate with Ar/He and N 2 /CO 2 , strongly suggesting that H 2 O/CO 2 is controlled by addition of steam boiled from water rich in atmospheric gases. Moreover, H 2 O/CO 2 varies systematically with geographic location, such that boiling is more enhanced in some areas than others. The δ 13 C and 3 He/CO 2 of gases reflect a dominant mantle origin for CO 2 in Yellowstone gas. The mantle signature is most evident at Mud Volcano, which hosts gases with the lowest H 2 O/CO 2 , lowest CH 4 concentrations and highest He isotope ratios (~16Ra), consistent with either a young subsurface intrusion or less input of crustal and meteoric gas than any other location at Yellowstone. Across the YPVF, He isotope ratios ( 3 He/ 4 He) inversely vary with He concentrations, and reflect varied amounts of long- stored, radiogenic He added to the magmatic endmember within the crust. Similarly, addition of CH4 from organic-rich sediments is common in the eastern thermal areas at Yellowstone. Overall, Yellowstone gases reflect addition of deep, high-temperature magmatic gas (CO 2 -rich), lower-temperatures crustal gases ( 4 He- and CH 4 -bearing), and those gases (N 2 , Ne, Ar) added principally through boiling of the meteoric-water-derived geothermal liquid found in the upper few kilometers. We also briefly explore the pathways by which Cl, F, and S, move through the crust.

Montana, Wyoming↗
USGS2016

The potassic sedimentary rocks in Gale Crater, Mars, as seen by ChemCam Onboard Curiosity

The Mars Science Laboratory rover Curiosity encountered potassium-rich clastic sedimentary rocks at two sites in Gale Crater, the waypoints Cooperstown and Kimberley. These rocks include several distinct meters thick sedimentary outcrops ranging from fine sandstone to conglomerate, interpreted to record an ancient fluvial or fluvio-deltaic depositional system. From ChemCam Laser-Induced Breakdown Spectroscopy (LIBS) chemical analyses, this suite of sedimentary rocks has an overall mean K 2 O abundance that is more than 5 times higher than that of the average Martian crust. The combined analysis of ChemCam data with stratigraphic and geographic locations reveals that the mean K 2 O abundance increases upward through the stratigraphic section. Chemical analyses across each unit can be represented as mixtures of several distinct chemical components, i.e., mineral phases, including K-bearing minerals, mafic silicates, Fe-oxides, and Fe-hydroxide/oxyhydroxides. Possible K-bearing minerals include alkali feldspar (including anorthoclase and sanidine) and K-bearing phyllosilicate such as illite. Mixtures of different source rocks, including a potassium-rich rock located on the rim and walls of Gale Crater, are the likely origin of observed chemical variations within each unit. Physical sorting may have also played a role in the enrichment in K in the Kimberley formation. The occurrence of these potassic sedimentary rocks provides additional evidence for the chemical diversity of the crust exposed at Gale Crater.

Journal of Geophysical Research↗
USGS2024

Factors influencing the prevalence of hyperpigmented melanistic lesions in smallmouth bass Micropterus dolomieu in the Susquehanna River Basin, Pennsylvania

Hyperpigmented melanistic lesions (HPMLs) are a visual anomaly documented on the skin of smallmouth bass Micropterus dolomieu in the Susquehanna River Basin, Pennsylvania and in numerous other geographical locations. Currently, there is a lack of information on environmental and fish characteristics that may influence the prevalence of HPMLs associated with a recently described Adomavirus . The goal of this study was to understand potential drivers associated with HPMLs in socioeconomically and ecologically important riverine smallmouth bass populations. A total of 16,220 smallmouth bass were collected and examined for HPMLs between 2012 and 2022 in the Susquehanna River Basin. Overall, HPMLs were documented on 2.9% of fish collected. The interaction between temperature and fish size suggested differing relationships between shorter and longer fish with respect to temperature. Predicted probability of HPML prevalence ranged from 1.1% (95% CI = 0.3, 3.2) at 4°C to 0.01% (CI = 0.00, 0.04) at 26°C for an age-0 (125 mm) fish. In contrast, predicted probability of HPML prevalence ranged from 10.5% (95% CI = 5.8, 18.9) at 4°C to 0.8% (CI = 0.4, 1.5) at 26°C for an adult (322 mm) fish. Overall, HPMLs were more common in longer fish during cooler temperature periods which also corresponds to key life history periods for smallmouth bass (e.g., pre-spawn and overwintering) and could represent different exposure histories for juvenile and adult fish.

Pennsylvania↗
USGS1995

Disturbance and recovery of the Louisiana coastal marsh landscape from the impacts of Hurricane Andrew

The impact of Hurricane Andrew on the Louisiana coastal landscape and the initial recovery of wetland plant communities was determined from extensive surveys of a large geographic region of coastal marsh near Atchafalaya Bay and intensive studies of an oligohaline marsh on Otter Bayou. Wind and water movements associated with the hurricane resulted in the formation of compressed marsh, thick sediment deposits, wrack deposition, areas of salt burning, and scour. No sites were entirely without some impact. Sediments were deposited over large areas of coastal marsh. Marsh sites near Atchafalaya Bay had the thickest post-storm accumulations documented, up to 16 cm on average, while inland marsh sites accumulated lesser amounts of sediments. The nature of the sediment deposited on the marsh surface varied with location relative to the path of the storm and sources of sediment. Lateral compression resulted in surface relief 5-10 times greater than normal surface relief. Plant cover quickly recovered in all hurricane impact types except for scour areas and areas of thick wrack accumulation. Shifts in species dominance occurred in laterally compressed areas and are related to increased elevations. These findings suggest that hurricanes result in a variety of impacts in coastal Louisiana marshes and that the heterogeneity of the coastal landscape contributes to the magnitude and distribution of these impacts.

Louisiana↗
USGS2012

Dust deposition in southern Nevada and California, 1984–1989: Relations to climate, source area, and source lithology

Dust samples collected annually for 5 years from 55 sites in southern Nevada and California provide the first regional source of information on modern rates of dust deposition, grain size, and mineralogical and chemical composition relative to climate and to type and lithology of dust source. The average silt and clay flux (rate of deposition) in southern Nevada and southeastern California ranges from 4.3 to 15.7 g/m 2 /yr, but in southwestern California the average silt and clay flux is as high as 30 g/m 2 /yr. The climatic factors that affect dust flux interact with each other and with the factors of source type (playas versus alluvium), source lithology, geographic area, and human disturbance. Average dust flux increases with mean annual temperature but is not correlated to decreases in mean annual precipitation because the regional winds bring dust to relatively wet areas. In contrast, annual dust flux mostly reflects changes in annual precipitation (relative drought) rather than temperature. Although playa and alluvial sources produce about the same amount of dust per unit area, the total volume of dust from the more extensive alluvial sources is much larger. In addition, playa and alluvial sources respond differently to annual changes in precipitation. Most playas produce dust that is richer in soluble salts and carbonate than that from alluvial sources (except carbonate‐rich alluvium). Gypsum dust may be produced by the interaction of carbonate dust and anthropogenic or marine sulfates. The dust flux in an arid urbanizing area may be as much as twice that before disturbance but decreases when construction stops. The mineralogic and major‐oxide composition of the dust samples indicates that sand and some silt is locally derived and deposited, whereas clay and some silt from different sources can be far‐traveled. Dust deposited in the Transverse Ranges of California by the Santa Ana winds appears to be mainly derived from sources to the north and east.

California, Nevada↗
USGS2012

Geochemical evidence for water‐rock interaction along the San Andreas and Garlock Faults of California

Mesozoic granitoid rocks adjacent to the San Andreas fault in central California have retained their radiogenic Ar for the last 70 m.y. but have, generally, the highest 18 O and H 2 O + contents and the lowest D contents of all the granitoid rocks in California. The geographical coincidence of the D, 18 O, and H 2 O + patterns with the present trace of the San Andreas fault leave little doubt that some kind of groundwater circulation system has operated in the vicinity of the fault in central California. Similar isotopic patterns exist in rocks along the Garlock fault. These water‐rock interactions probably took place at temperatures <200°C, although depth, extent, and timing are not resolved. Stable isotope compositions of rocks from many localities of the earth have provided unambiguous proof that meteoric waters have descended to depths at least as great as 8 to 10 km when a heat source such as a cooling pluton was present. Massive circulation of groundwater is common in the upper crust of tectonically active areas and may affect the frictional stress state along major faults. The geochemical evidence for extensive deep circulation of groundwater and the relatively high permeabilities for most rocks of the upper crust recently compiled by Brace (1980) argues against nearly lithostatic fluid pressures as an ambient condition of the upper crust. Groundwater circulation along the San Andreas provides an efficient mechanism for diffusing the heat flow anomaly that arises in heat transport calculations that are based on thermal conduction alone.

California↗
USGS2015

Cyclic avian mass mortality in the northeastern United States is associated with a novel orthomyxovirus

Since 1998, cyclic mortality events in common eiders ( Somateria mollissima ), numbering in the hundreds to thousands of dead birds, have been documented along the coast of Cape Cod, Massachusetts, USA. Although longitudinal disease investigations have uncovered potential contributing factors responsible for these outbreaks, detecting a primary etiological agent has proven enigmatic. Here we identify a novel orthomyxovirus, tentatively named Wellfleet Bay virus (WFBV), as a potential causative agent of these outbreaks. Genomic analysis of WFBV revealed that it is most closely related to members of the Quaranjavirus genus within the family Orthomyxoviridae . Similar to other members of the genus, WFBV contains an alphabaculovirus gp64-like glycoprotein, which was demonstrated to have fusion activity, and also tentatively suggests that ticks (and/or insects) may vector the virus in nature. However, in addition to the six RNA segments encoding the prototypical structural proteins identified in other quaranjaviruses, a previously unknown RNA segment (segment 7) encoding a novel protein designated as VP7 was discovered in WFBV. Although WFBV shows low to moderate levels of sequence similarity to Quaranfil virus and Johnston Atoll virus , the original members of the Quaranjavirus genus, additional antigenic and genetic analyses demonstrated that it is closely related to the recently identified Cygnet River virus (CyRV) from South Australia, suggesting that WFBV and CyRV may be geographic variants of the same virus. Although the identification of WFBV in part may resolve the enigma of these mass mortality events, the details of the ecology and epidemiology of the virus remain to be determined. Importance The emergence or reemergence of viral pathogens resulting in large-scale outbreaks of disease in humans and/or animals is one of the most important challenges facing biomedicine. For example, understanding how orthomyxoviruses such as novel influenza A virus reassortants and/or mutants emerge to cause epidemic or pandemic disease is at the forefront of current global health concerns. Here we describe the emergence of a novel orthomyxovirus, Wellfleet Bay virus (WFBV), which has been associated with cyclic large-scale bird die-offs in the northeastern United States. This initial characterization study provides a foundation for further research into the evolution, epidemiology, and ecology of newly emerging orthomyxoviruses, such as WFBV, and their potential impacts on animal and/or human health.

Massachusets↗
USGS2011

Soil warming alters seed-bank responses across the geographic range of freshwater Taxodium distichum (Cupressaceae) swamps

Premise of the Study: Climate warming is predicted to have far‐reaching effects on the distribution of species, but those effects may depend on the flexibility of regenerating species in responding to climate gradients. We conducted a study to determine whether the variation in the response of seed banks to temperature varied across the latitudinal range of Taxodium distichum swamps in North America. • Methods: The soil was collected in a long‐term research network and heated experimentally to three current‐day spring normal soil temperatures (average maximum daily spring normal soil temperatures during May in Illinois, Arkansas, and Louisiana, USA, respectively: 22°, 25°, and 29°C). A “normal” is the mean temperature calculated over a 30‐yr interval (1971–2000). Seed‐bank density and biomass responses were examined in relation to latitude and difference in the soil temperature of the experiment and the spring normal. • Key Results: Using first‐ and second‐order regression analysis, we determined that the variation in total germination density was lowest mid‐range and in experimental soil temperatures similar to the spring normal. For some dominant species, the variance in germination density was higher in the northern ( Cephalanthus occidentalis ) or the southern part of the network ( Saururus cernuus and Polygonum pensylvanicum ). Overall, the variance of total biomass (root, shoot, whole plant) was higher if the experimental soil temperature was warmer than the spring normal. • Conclusions: Our results suggest that the regeneration of some populations of swamp species may have more flexibility to respond to climate warming than others.

Alabama, Arkansas, Florida, Georgia, Illinois, Ken↗
USGS2021

Invaders from islands: Thermal matching, potential or flexibility?

Native-range thermal constraints may not reflect the geographical distributions of species introduced from native island ranges in part due to rapid physiological adaptation in species introduced to new environments. Correlative ecological niche models may thus underestimate potential invasive distributions of species from islands. The northern curly-tailed lizard ( Leiocephalus carinatus ) is established in Florida, including populations north of its native range. Competing hypotheses may explain this distribution: Thermal Matching (distribution reflects thermal conditions of the native range), Thermal Potential (species tolerates thermal extremes absent in the native range) and/or Thermal Flexibility (thermal tolerance reflects local thermal extremes). We rejected the Thermal Matching hypothesis by comparing ecological niche models developed from native vs. native plus invasive distributions; L. carinatus exists in areas of low suitability in Florida as predicted by the native-distribution model. We then compared critical thermal limits of L. carinatus from two non-native populations to evaluate the Thermal Potential and Flexibility hypotheses: one matching native range latitudes, and another 160 km north of the native range that experiences more frequent cold weather events. Critical thermal minima in the northern population were lower than in the south, supporting the Thermal Flexibility hypothesis, whereas critical thermal maxima did not differ.

Florida↗
USGS2007

Nutrients discharged to the Mississippi River from eastern Iowa watersheds, 1996-1997

The introduction of nutrients from chemical fertilizer, animal manure, wastewater, and atmospheric deposition to the eastern Iowa environment creates a large potential for nutrient transport in watersheds. Agriculture constitutes 93 percent of all land use in eastern Iowa. As part of the U.S. Geological Survey National Water Quality Assessment Program, water samples were collected (typically monthly) from six small and six large watersheds in eastern Iowa between March 1996 and September 1997. A Geographic Information System (GIS) was used to determine land use and quantify inputs of nitrogen and phosphorus within the study area. Streamliow from the watersheds is to the Mississippi River. Chemical fertilizer and animal manure account for 92 percent of the estimated total nitrogen and 99.9 percent of the estimated total phosphorus input in the study area. Total nitrogen and total phosphorus loads for 1996 were estimated for nine of the 12 rivers and creeks using a minimum variance unbiased estimator model. A seasonal pattern of concentrations and loads was observed. The greatest concentrations and loads occur in the late spring to early summer in conjunction with row-crop fertilizer applications and spring nmoff and again in the late fall to early winter as vegetation goes into dormancy and additional fertilizer is applied to row-crop fields. The three largest rivers in eastern Iowa transported an estimated total of 79,000 metric tons of total nitrogen and 6,800 metric tons of total phosphorus to the Mississippi River in 1996. The estimated mass of total nitrogen and total phosphorus transported to the Mississippi River represents about 19 percent of all estimated nitrogen and 9 percent of all estimated phosphorus input to the study area.

Iowa↗
USGS2017

Semipermanent GPS (SPGPS) as a volcano monitoring tool: Rationale, method, and applications

Semipermanent GPS (SPGPS) is an alternative to conventional campaign or survey-mode GPS (SGPS) and to continuous GPS (CGPS) that offers several advantages for monitoring ground deformation. Unlike CGPS installations, SPGPS stations can be deployed quickly in response to changing volcanic conditions or earthquake activity such as a swarm or aftershock sequence. SPGPS networks can be more focused or more extensive than CGPS installations, because SPGPS equipment can be moved from station to station quickly to increase the total number of stations observed in a given time period. SPGPS networks are less intrusive on the landscape than CGPS installations, which makes it easier to satisfy land-use restrictions in ecologically sensitive areas. SPGPS observations are preferred over SGPS measurements because they provide better precision with only a modest increase in the amount of time, equipment, and personnel required in the field. We describe three applications of the SPGPS method that demonstrate its utility and flexibility. At the Yellowstone caldera, Wyoming, a 9-station SPGPS network serves to densify larger preexisting networks of CGPS and SGPS stations. At the Three Sisters volcanic center, Oregon, a 14-station SPGPS network complements an SGPS network and extends the geographic coverage provided by 3 CGPS stations permitted under wilderness land-use restrictions. In the Basin and Range province in northwest Nevada, a 6-station SPGPS network has been established in response to a prolonged earthquake swarm in an area with only sparse preexisting geodetic coverage. At Three Sisters, the estimated precision of station velocities based on annual ~ 3 month summertime SPGPS occupations from 2009 to 2015 is approximately half that for nearby CGPS stations. Conversely, SPGPS-derived station velocities are about twice as precise as those based on annual ~ 1 week SGPS measurements. After 5 years of SPGPS observations at Three Sisters, the precision of velocity determinations is estimated to be 0.5 mm/yr in longitude, 0.6 mm/yr in latitude, and 0.8 mm/yr in height. We conclude that an optimal approach to monitoring volcano deformation includes complementary CGPS and SPGPS networks, periodic InSAR observations, and measurements from in situ borehole sensors such as tiltmeters or strainmeters. This comprehensive approach provides the spatial and temporal detail necessary to adequately characterize a complex and evolving deformation pattern. Such information is essential to multi-parameter models of magmatic or tectonic processes that can help to guide research efforts, and also to inform hazards assessments and land-use planning decisions.

Journal of Volcanology and Geothermal Research↗
USGS2024

Applying mark-resight, count, and telemetry data to estimate effective sampling area and fish density with stationary underwater cameras

Accurate estimates of abundance and density for geographically open populations must account for the effective sampling area (ESA) of sampling gears. We describe a Marked N-Mixture model to estimate ESA and density (number of individuals/unit area) from repeated counts of unmarked and marked individuals, integrating mark-resight, camera counts, and telemetry data of red snapper ( Lutjanus campechanus ) at a 1.6 km 2 reef off North Carolina, USA. Cameras recorded observations of unmarked and marked individuals, whereas telemetry data indicated the number of tagged fish present on the reef. We estimated density (95 individuals/km 2 , 95%CI: 58–149), ESA (which was lower when current direction was towards the camera), detection probability (0.06, 95%CI: 0.03–0.09), and covariate relationships. Simulation studies under different scenarios of data quality and space use identified positive bias in density estimates from N-mixture models due to fish movement. In contrast, the Marked N-Mixture model returned unbiased estimates of density, ESA, and detection parameters, and appears to be a more robust method for modeling density given the data available for this analysis. This approach can be applied to other populations where count and telemetry data overlap in space and time.

North Carolina↗
USGS2025

The importance of sampling design for unbiased estimation of survival using joint live-recapture and live resight models

Survival is a key life history parameter that can inform management decisions and basic life history research. Because true survival is often confounded with emigration from the study area, many studies are forced to estimate apparent survival (i.e., probability of surviving and remaining inside the study area), which can be much lower than true survival for highly mobile species. One method for estimating true survival is the Barker joint live-recapture/live-resight (JLRLR) model, which combines capture data from a study area (hereafter the ‘capture site’) with resighting data from a broader geographic area. This model assumes that live resights occur throughout the entire area where animals can disperse to and this assumption is often not met in practice. Here we use simulation to evaluate survival bias from a JLRLR model under study design scenarios that differ in the site selection for resights: global, random, fixed including the capture site, and fixed excluding the capture site. Simulation results indicate that fixed designs that included the capture site showed negative survival bias, whereas fixed designs that excluded the capture site exhibited positive survival bias. The magnitude of the bias was dependent on movement and survival, where scenarios with high survival and frequent movement had minimal bias. In an effort to help minimize bias, we developed a multistate version of the JLRLR and demonstrated reductions in survival bias compared to the single-state version for most designs. Our results suggest minimizing bias can be accomplished by: 1) using a random resight design when feasible if global sampling is not possible, 2) using the multistate JLRLR model when appropriate, 3) including the capture site in the resight sampling frame when possible, and 4) reporting survival as apparent survival if fixed sites are used for resight with the single state JLRLR model.

Peer Community Journal↗
USGS2016

Modeling the geographic distribution of Ixodes scapularis and Ixodes pacificus (Acari: Ixodidae) in the contiguous United States

In addition to serving as vectors of several other human pathogens, the black-legged tick, Ixodes scapularis Say, and western black-legged tick, Ixodes pacificus Cooley and Kohls, are the primary vectors of the spirochete ( Borrelia burgdorferi ) that causes Lyme disease, the most common vector-borne disease in the United States. Over the past two decades, the geographic range of I. pacificus has changed modestly while, in contrast, the I. scapularis range has expanded substantially, which likely contributes to the concurrent expansion in the distribution of human Lyme disease cases in the Northeastern, North-Central and Mid-Atlantic states. Identifying counties that contain suitable habitat for these ticks that have not yet reported established vector populations can aid in targeting limited vector surveillance resources to areas where tick invasion and potential human risk are likely to occur. We used county-level vector distribution information and ensemble modeling to map the potential distribution of I. scapularis and I. pacificus in the contiguous United States as a function of climate, elevation, and forest cover. Results show that I. pacificus is currently present within much of the range classified by our model as suitable for establishment. In contrast, environmental conditions are suitable for I. scapularis to continue expanding its range into northwestern Minnesota, central and northern Michigan, within the Ohio River Valley, and inland from the southeastern and Gulf coasts. Overall, our ensemble models show suitable habitat for I. scapularis in 441 eastern counties and for I. pacificus in 11 western counties where surveillance records have not yet supported classification of the counties as established.

Journal of Medical Entomology↗
USGS2010

Multilocus patterns of nucleotide polymorphism and demographic change in Taxodium distichum (Cupressaceae) in the lower Mississippi River alluvial valley

• Premise of the Study: Studies of the geographic patterns of genetic variation can give important insights into the past population structure of species. Our study species, Taxodium distichum L. (bald‐cypress), prefers riparian and wetland habitats and is widely distributed in southeastern North America and Mexico. We compared the genetic variation of T. distichum with that of its close relative, Cryptomeria japonica , which is endemic to Japan. • Methods: Nucleotide polymorphisms of T. distichum in the lower Mississippi River alluvial valley, USA, were examined at 10 nuclear loci. • Key Results: The average nucleotide diversity at silent sites, π sil , across the 10 loci in T. distichum was higher than that of C. japonica (π sil = 0.00732 and 0.00322, respectively). In T. distichum , Tajima's D values were each negative at 9 out of 10 loci, which suggests a recent population expansion. Maximum‐likelihood and Bayesian estimations of the exponential population growth rate ( g ) of T. distichum populations indicated that this species had expanded approximately at the rate of 1.7–1.0 × 10 –6 per year in the past. • Conclusions: Taxodium distichum had significantly higher nucleotide variation than C. japonica , and its patterns of polymorphism contrasted strikingly with those of the latter, which previously has been inferred to have experienced a reduction in population size.

Arkansas, Louisiana, Mississippi, Tennessee↗
USGS2013

Predicting what helminth parasites a fish species should have using Parasite Co-occurrence Modeler (PaCo)

Fish pathologists are often interested in which parasites would likely be present in a particular host. Parasite Co-occurrence Modeler (PaCo) is a tool for identifying a list of parasites known from fish species that are similar ecologically, phylogenetically, and geographically to the host of interest. PaCo uses data from FishBase (maximum length, growth rate, life span, age at maturity, trophic level, phylogeny, and biogeography) to estimate compatibility between a target host and parasite species–genera from the major helminth groups (Acanthocephala, Cestoda, Monogenea, Nematoda, and Trematoda). Users can include any combination of host attributes in a model. These unique features make PaCo an innovative tool for addressing both theoretical and applied questions in parasitology. In addition to predicting the occurrence of parasites, PaCo can be used to investigate how host characteristics shape parasite communities. To test the performance of the PaCo algorithm, we created 12,400 parasite lists by applying any possible combination of model parameters (248) to 50 fish hosts. We then measured the relative importance of each parameter by assessing their frequency in the best models for each host. Host phylogeny and host geography were identified as the most important factors, with both present in 88% of the best models. Habitat (64%) was identified in more than half of the best models. Among ecological parameters, trophic level (41%) was the most relevant while life span (34%), growth rate (32%), maximum length (28%), and age at maturity (20%) were less commonly linked to best models. PaCo is free to use at www.purl.oclc.org/fishpest .

Journal of Parasitology↗
USGS2025

Factors associated with survival, recovery, and movements in the western Gulf Coast population of mottled ducks

The mottled duck ( Anas fulvigula ) is nonmigratory and a priority species for regional conservation and management because of its limited range and declining population trajectory in the western Gulf Coast (WGC) of Louisiana and Texas, USA. We developed multistate dead-recovery models for banding and recovery data (1997–2020) to evaluate potential drivers of survival, recovery, and post-summer movements for the WGC population of mottled ducks in Louisiana and Texas. Annual survival was most strongly associated with sex and year, with females having lower survival ( ± = 0.544 ± 0.114) than males (0.619 ± 0.062). Of the 32 environmental covariates tested, fall precipitation was the factor most strongly associated with survival. Conditional recovery probability (i.e., given mortality, the probability a bird had been shot by a hunter, retrieved, and had their band number reported) varied by sex, age, geographic state, and year, with juvenile males generally having highest conditional recovery (0.303 ± 0.072), followed by juvenile females (0.201 ± 0.100), adult males (0.156 ± 0.038), and adult females (0.095 ± 0.057). Estimates of harvest probabilities followed similar patterns as conditional recovery. Models containing effects of harvest regulations on conditional recovery were not competitive compared to models with general year effects; however, post hoc analyses suggested conditional recovery and harvest probabilities for adult and juvenile females decreased with the daily bag limit reduction in Louisiana and, for juvenile females, implementation of the 5-day closure regulation in Texas. Post-summer movement was substantially higher in the direction of Texas to Louisiana, decreased with distance to the Louisiana–Texas border, was higher for males than females, and varied with winter precipitation. These results contribute to a better understanding of the factors influencing demographic performance, harvest, and movement between states with differing harvest regulations and environmental pressures, which is important for mottled duck conservation planning. Wildlife managers can consider expanding banding effort throughout the full range of the WGC population and collecting and reporting live-recapture data to allow for stronger population-level inferences and increased power to detect differences in important demographic parameters at more refined spatial scales.

Louisiana, Texas↗