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At least 1,189 records · Page 66Linked to original sources
USGS2015

Estimating changes in riparian and channel features along the Trinity River downstream of Lewiston Dam, California, 1980 to 2011

Dam construction, flow diversion, and legacy landuse effects reduced the transport capacity, sediment supply, channel complexity and floodplain-connectivity along the Trinity River, CA below Lewiston Dam. This study documents the geomorphic evolution of the Trinity River Restoration Program’s intensively managed 65-km long restoration reach from 1980 to 2011. The nature and extent of riparian and channel changes were assessed using a series of geomorphic feature maps constructed from ortho-rectified photography acquired at low flow conditions in 1980, 1997, 2001, 2006, 2009, and 2011. Since 1980 there has been a general conversion of riparian to channel features and expansion of the active channel area. The primary mechanism for expansion of the active channel was bank erosion from 1980 to 1997 and channel widening was well distributed longitudinally throughout the study reach. Subsequent net bar accretion from 1997 to 2001, followed by slightly higher net bar scour from 2001 to 2006, occurred primarily in the central and lower reaches of the study area. In comparison, post-2006 bank and bar changes were spatially-limited to reaches with sufficient local transport capacity or sediment supply supported by gravel augmentation, mechanical channel rehabilitation, and tributary contributions to flow and sediment supply. A series of tributary floods in 1997, 1998 and 2006 were the primary factors leading to documented increases in channel complexity and floodplain connectivity. During the post-2006 period managed flow releases, in the absence of large magnitude tributary flooding, combined with gravel augmentation and mechanical restoration caused localized increases in sediment supply and transport capacity leading to smaller but measurable increases in channel complexity and floodplain connectivity primarily in the upper river below Lewiston Dam.

California↗
USGS1979

Digital model of the Bayou Bartholomew alluvial aquifer stream system, Arkansas

A digital model of the Bayou Bartholomew aquifer-stream system in Arkansas was calibrated for the purpose of predicting hydrologic responses to stresses of water development. The simulated-time span for model calibration was from 1953 to 1970, during which time the system was stressed largely by ground- and surface-water diversions for rice irrigation. The model was calibrated by comparing groundwater-level and streamflow data with model-derived groundwater levels and streamflow. In the calibrated model, the ratio of model-derived to observed streamflows for 17 subbasins averaged 1.1; the ratios among the subbasins ranged from 0.8 to 1.6. The average deviation of the differences between model-derived and observed groundwater levels at 47 nodes was 0.2; the average among the nodes ranged from -2.3 to 10.4. The average standard deviation of the differences between the model-derived and observed groundwater levels was 3.5; the average among the nodes ranged from 0.4 to 10.5. The model will provide projections of changes in the potentiometric surface resulting from (1) changes in the rate or distribution of groundwater pumpage or (2) changes in the stage of streams and reservoirs. The model will provide only approximate projections of the streamflow.

Arkansas↗
USGS2008

Evaluation of selected model constraints and variables on simulated sustainable yield from the Mississippi River Valley alluvial aquifer system in Arkansas

An existing conjunctive use optimization model of the Mississippi River Valley alluvial aquifer was used to evaluate the effect of selected constraints and model variables on ground-water sustainable yield. Modifications to the optimization model were made to evaluate the effects of varying (1) the upper limit of ground-water withdrawal rates, (2) the streamflow constraint associated with the White River, and (3) the specified stage of the White River. Upper limits of ground-water withdrawal rates were reduced to 75, 50, and 25 percent of the 1997 ground-water withdrawal rates. As the upper limit is reduced, the spatial distribution of sustainable pumping increases, although the total sustainable pumping from the entire model area decreases. In addition, the number of binding constraint points decreases. In a separate analysis, the streamflow constraint associated with the White River was optimized, resulting in an estimate of the maximum sustainable streamflow at DeValls Bluff, Arkansas, the site of potential surface-water withdrawals from the White River for the Grand Prairie Area Demonstration Project. The maximum sustainable streamflow, however, is less than the amount of streamflow allocated in the spring during the paddlefish spawning period. Finally, decreasing the specified stage of the White River was done to evaluate a hypothetical river stage that might result if the White River were to breach the Melinda Head Cut Structure, one of several manmade diversions that prevents the White River from permanently joining the Arkansas River. A reduction in the stage of the White River causes reductions in the sustainable yield of ground water.

Arkansas↗
USGS2023

FishPass baseline assessment of fish community assemblage and migratory patterns in in the Boardman River, Traverse City, Michigan, USA

This report on baseline assessment of fish community assemblage and migratory patterns of fishes in the lower Boardman River (LBR; Traverse City, MI (USA)) is one of four assessment projects conceived circa 2017 after the Boardman (Ottaway) River was selected by the Great Lakes Fishery Commission (GLFC) and collaborating agencies as the future site of the Selective Bi-directional Fish Passage (FishPass) project. This report describes the results from fisheries community sampling from 2017-2021 and the concurrent bio-telemetry project aimed at understanding phenological changes in the fish community and movement and space-use of a variety of large-bodied fishes in the LBR against which selective fish passage treatments will be developed and evaluated. Fish migration in riverine environments is a growing area of concern as mounting anthropogenic influences, particularly fragmentation from dams and barriers, constitute a major threat to global river species diversity. Specifically, In the Laurentian Great Lakes basin, more than 250,000 dams, weirs, culverts, and other significant obstructions prevent the movement of species both between the Great Lakes and rivers, and within rivers. Barriers impede the movement of fishes between areas critical to the completion of their lifecycle, affecting both population and ecosystem viability. However, a conundrum arises in that the same barriers can also prevent the upstream invasion of non-native or undesirable species (most notably the sea lamprey Petromyzon marinus in the Great Lakes),prevent the transfer of contaminants and diseases, halt deleterious genes, provide recreational opportunities, or generate power. As a result, fish passage solutions with the capability of selectively passing desirable taxa while restricting the dispersal of undesirable taxa (selective connectivity) are sought to solve this connectivity conundrum. FishPass is a multi-agency initiative planned to replace the Union Street Dam on the Boardman River in Traverse City,MI (USA), aimed at developing and implementing automatic or semiautomatic selective bi-directional fish guidance, sorting, and passage techniques and technologies. Pivotal to both the successful development of selective connectivity and assessment of its effects is a more complete understanding of the Boardman River’s fishery. Specifically, understanding the species and size composition of the fish community, fish movement phenology and the associated abiotic conditions. Fish community sampling confirmed the presence of 28 unique species in the LBR (Boardman River reach below Union Street Dam). Passive Integrated Transponder (PIT) tag telemetry increased the resolution of phenological shifts in the fish community that could not have been captured from periodic fish sampling. This data demonstrates large variation within species and overlap between species presence. However, discrete periods of presence were identified across most species when considering the central tendencies in the distribution of their presence. Rainbow trout Oncorhynchus mykiss were found to be omni-present in the river while brown trout Salmo trutta and smallmouth bass Micropterus dolomieu also persisted throughout a majority of the year; all of which will require continually sorting at FishPass. PIT tag telemetry also provided the important understanding that individuals (3-64%) of all species return to the LBR across multiple years. Radio telemetry (RT) proved useful in refining the entry and exit timing and in evaluating the proportion of individuals that encountered the current Union Street Dam and Kid’s Creek (the only tributary confluence below the Union Street Dam) across six species (common white sucker Catostomus commersonii, rainbow trout, smallmouth bass, walleye Sander vitreus, brown trout, and common carp Cyprinus carpio). The RT results show that these species are present in FishPass Research Publication: baseline assessment of fish community assemblage and migratory pattern in the Boardman River, Traverse City, Michigan, USA November 2023 7 between April and August. Our analysis also demonstrated that not all fish that entered the river proceeded to the Union Street Dam, but those that did, did so prior to being detected encountering Kid’s Creek. Common white sucker and rainbow trout were the only species to be detected encountering Kid’s Creek. Collectively, the results of this study provide a baseline understanding of the seasonal fish diversity and relative abundance of fishes in the LBR, and a basic description of observed movement patterns of a subset of species in the context of seasonal phenology, entry and exit behavior within the LBR, and the propensity at which telemetered individuals encounter the Union Street dam and/or Kid’s Creek.

Michigan↗
USGS2016

The importance of base flow in sustaining surface water flow in the Upper Colorado River Basin

The Colorado River has been identified as the most overallocated river in the world. Considering predicted future imbalances between water supply and demand and the growing recognition that base flow (a proxy for groundwater discharge to streams) is critical for sustaining flow in streams and rivers, there is a need to develop methods to better quantify present-day base flow across large regions. We adapted and applied the spatially referenced regression on watershed attributes (SPARROW) water quality model to assess the spatial distribution of base flow, the fraction of streamflow supported by base flow, and estimates of and potential processes contributing to the amount of base flow that is lost during in-stream transport in the Upper Colorado River Basin (UCRB). On average, 56% of the streamflow in the UCRB originated as base flow, and precipitation was identified as the dominant driver of spatial variability in base flow at the scale of the UCRB, with the majority of base flow discharge to streams occurring in upper elevation watersheds. The model estimates an average of 1.8 × 10 10 m 3 /yr of base flow in the UCRB; greater than 80% of which is lost during in-stream transport to the Lower Colorado River Basin via processes including evapotranspiration and water diversion for irrigation. Our results indicate that surface waters in the Colorado River Basin are dependent on base flow, and that management approaches that consider groundwater and surface water as a joint resource will be needed to effectively manage current and future water resources in the Basin.

Arizona, Colorado, New Mexico, Utah, Wyoming↗
USGS2012

The genetic structure of a relict population of wood frogs

Habitat fragmentation and the associated reduction in connectivity between habitat patches are commonly cited causes of genetic differentiation and reduced genetic variation in animal populations. We used eight microsatellite markers to investigate genetic structure and levels of genetic diversity in a relict population of wood frogs ( Lithobates sylvatica ) in Rocky Mountain National Park, Colorado, where recent disturbances have altered hydrologic processes and fragmented amphibian habitat. We also estimated migration rates among subpopulations, tested for a pattern of isolation-by-distance, and looked for evidence of a recent population bottleneck. The results from the clustering algorithm in Program STRUCTURE indicated the population is partitioned into two genetic clusters (subpopulations), and this result was further supported by factorial component analysis. In addition, an estimate of FST (FST = 0.0675, P value \0.0001) supported the genetic differentiation of the two clusters. Estimates of migration rates among the two subpopulations were low, as were estimates of genetic variability. Conservation of the population of wood frogs may be improved by increasing the spatial distribution of the population and improving gene flow between the subpopulations. Construction or restoration of wetlands in the landscape between the clusters has the potential to address each of these objectives.

Colorado↗
USGS2015

Sediment and nutrient trapping as a result of a temporary Mississippi River floodplain restoration: The Morganza Spillway during the 2011 Mississippi River Flood

The 2011 Mississippi River Flood resulted in the opening of the Morganza Spillway for the second time since its construction in 1954 releasing 7.6 km 3 of water through agricultural and forested lands in the Morganza Floodway and into the Atchafalaya River Basin. This volume, released over 54 days, represented 5.5% of the Mississippi River (M.R.) discharge and 14% of the total discharge through the Atchafalaya River Basin (A.R.B.) during the Spillway operation and 1.1% of the M.R. and 3.3% of the A.R.B. 2011 water year discharge. During the release, 1.03 teragrams (Tg) of sediment was deposited on the Morganza Forebay and Floodway and 0.26 Tg was eroded from behind the Spillway structure. The majority of deposition (86 %) occurred in the Forebay (upstream of the structure) and within 4 km downstream of the Spillway structure with minor deposition on the rest of the Floodway. There was a net deposition of 26 × 10 −4 Tg of N and 5.36 × 10 −4 Tg of P, during the diversion, that was equivalent to 0.17% N and 0.33% P of the 2011 annual M.R. load. Median deposited sediment particle size at the start of the Forebay was 13 μm and decreased to 2 μm 15 km downstream of the Spillway structure. Minimal accretion was found greater than 4 km downstream of the structure suggesting the potential for greater sediment and nutrient trapping in the Floodway. However, because of the large areas involved, substantial sediment mass was deposited even at distances greater than 30 km. Sediment and nutrient deposition on the Morganza Floodway was limited because suspended sediment was quickly deposited along the flowpath and not refreshed by incremental water exchanges between the Atchafalaya River (A.R.) and the Floodway. Sediment and nutrient trapping could have been greater and more evenly distributed if additional locations of hydraulic input from and outputs to the A.R. (connectivity) were added.

Louisiana↗
USGS2020

A call for global action to conserve native trout in the 21st century and beyond

Trout and char (hereafter, trout ) represent some of the more culturally, economically and ecologically important taxa of freshwater fishes worldwide (Kershner, Williams, Gresswell, & Lobón‐Cerviá, 2019a ). Native to all continents in the Northern Hemisphere (as well as western Mediterranean Africa), trout belong to seven genera ( Oncorhynchus , Salvelinus, Salmo , Hucho, Parahucho, Brachymystax and Salvethymus ), which are distributed across more than 60 countries (Muhlfeld et al., 2019 ). Despite their broad importance as indicators of biodiversity in cold‐water ecosystems (Haak & Williams, 2013 ), as well as cultural icons for food and recreation, nearly half of the world's recognised trout species (IUCN, 2018 ) are imperilled or at risk of global extinction (Muhlfeld et al., 2018 , 2019 ). The root causes of their vulnerability include broad‐scale alteration of landscapes and watersheds, dams, overharvest, pollution, interactions with hatchery‐bred conspecifics and non‐native species. However, emerging threats such as climate change and related problems such as the spread of diseases and parasites pose significant challenges and uncertainties to native trout and their habitats (Kovach et al., 2016 ; Muhlfeld et al., 2018 ). Ultimately, conservation of native trout depends on understanding their diversity, a willingness to address threats at their root causes and implementing progressive conservation solutions that promote persistence of these iconic species in the face of growing human pressures.

Ecology of Freshwater Fish↗
USGS2005

Effects of urbanization on the distribution and abundance of amphibians and invasive species in southern California streams

Urbanization negatively affects natural ecosystems in many ways, and aquatic systems in particular. Urbanization is also cited as one of the potential contributors to recent dramatic declines in amphibian populations. From 2000 to 2002 we determined the distribution and abundance of native amphibians and exotic predators and characterized stream habitat and invertebratecommunities in 35 streams in an urbanized landscape north of Los Angeles (U.S.A.). We measured watershed development as the percentage of area within each watershed occupied by urban land uses. Streams in more developed watersheds often had exotic crayfish (Procambarus clarkii) and fish, and had fewer native species such as California newts (Taricha torosa) and California treefrogs (Hyla cadaverina). These effects seemed particularly evident above 8% development, a result coincident with other urban stream studies that show negative impacts beginning at 10-15% urbanization. For Pacific treefrogs (H. regilla), the most widespread native amphibian, abundance was lower in the presence of exotic crayfish, although direct urbanization effects were not found. Benthic macroinvertebrate communities were also less diverse in urban streams, especially for sensitive species. Faunal community changes in urban streams may be related to changes in physical stream habitat, such as fewer pool and more run habitats and increased water depth and flow, leading to more permanent streams. Variation in stream permanence was particularly evident in 2002, a dry year when many natural streams were dry but urban streams were relatively unchanged. Urbanization has significantly altered stream habitat in this region and may enhance invasion by exotic species and negatively affect diversity and abundance of native amphibians. ??2005 Society for Conservation Biology.

Conservation Biology↗
USGS2005

Patterns of plant species richness, rarity, endemism, and uniqueness in an arid landscape

Most current conservation literature focuses on the preservation of hotspots of species diversity and endemism, as if the two were geographically synonymous. At landscape scales this may not be the case. We collected data from 367 1000-m 2 plots in the Grand Staircase–Escalante National Monument, Utah, USA, to show that: (1) the vast majority of plant species are locally rare; (2) species-rich areas are generally in rare, mesic, or high-elevation habitats such as aspen stands or riparian zones high in soil N and P; (3) endemic species (to the Colorado Plateau and the Monument) were generally found in relatively species-rich, but low-elevation, xeric vegetation type areas low in soil P; (4) unique species assemblages were found in areas moderately high in endemism and species richness; and (5) nonnative plant species were widely distributed, but more prevalent in species-rich, mesic sites high in soil fertility or disturbed sites, and significantly less prevalent in plots with endemic species. We show that primary hotspots of species richness, high endemism, and unique species assemblages are not co-located on the landscape. Hence, conservation strategies may have to consider a much broader concept of “hotspots” to adequately preserve native plant species and the processes that foster persistence.

Ecological Applications↗
USGS2001

Geologic Map of the Thaumasia Region, Mars

The geology of the Thaumasia region (fig. 1, sheet 3) includes a wide array of rock materials, depositional and erosional landforms, and tectonic structures. The region is dominated by the Thaumasia plateau, which includes central high lava plains ringed by highly deformed highlands; the plateau may comprise the ancestral center of Tharsis tectonism (Frey, 1979; Plescia and Saunders, 1982). The extensive structural deformation of the map region, which is without parallel on Mars in both complexity and diversity, occurred largely throughout the Noachian and Hesperian periods (Tanaka and Davis, 1988; Scott and Dohm, 1990a). The deformation produced small and large extensional and contractional structures (fig. 2, sheet 3) that resulted from stresses related to the formation of Tharsis (Frey, 1979; Wise and others, 1979; Plescia and Saunders, 1982; Banerdt and others, 1982, 1992; Watters and Maxwell, 1986; Tanaka and Davis, 1988; Francis, 1988; Watters, 1993; Schultz and Tanaka, 1994), from magmatic-driven uplifts, such as at Syria Planum (Tanaka and Davis, 1988; Dohm and others, 1998; Dohm and Tanaka, 1999) and central Valles Marineris (Dohm and others, 1998, Dohm and Tanaka, 1999), and from the Argyre impact (Wilhelms, 1973; Scott and Tanaka, 1986). In addition, volcanic, eolian, and fluvial processes have highly modified older surfaces in the map region. Local volcanic and tectonic activity often accompanied episodes of valley formation. Our mapping depicts and describes the diverse terrains and complex geologic history of this unique ancient tectonic region of Mars. The geologic (sheet 1), paleotectonic (sheet 2), and paleoerosional (sheet 3) maps of the Thaumasia region were compiled on a Viking 1:5,000,000-scale digital photomosaic base. The base is a combination of four quadrangles: the southeast part of Phoenicis Lacus (MC–17), most of the southern half of Coprates (MC–18), a large part of Thaumasia (MC–25), and the northwest margin of Argyre (MC–26). The medium-resolution Viking images used for mapping and base preparation also formed the basis of the 1:2,000,000 scale subquadrangle series. Earlier geologic maps of all or parts of the region include: (1) maps of the Phoenicis Lacus, Coprates, Thaumasia, and Argyre quadrangles at 1:5,000,000 scale based mainly on Mariner 9 images (respectively, Masursky and others, 1978; McCauley, 1978; McGill, 1978; and Hodges, 1980), (2) the global map of Mars at 1:25,000,000 (Scott and Carr, 1978) compiled largely from the 1:5,000,000 scale geologic maps, (3) maps showing lava flows in the Tharsis region at 1:2,000,000 scale compiled from Viking and Mariner 9 images (Scott, 1981; Scott and Tanaka, 1981a, b; Scott and others, 1981), (4) the map of the western equatorial region of Mars at 1:15,000,000 scale based on Viking images (Scott and Tanaka, 1986), and (5) the map of the Valles Marineris region at 1:2,000,000 scale compiled from Viking images (Witbeck and others, 1991). The previous maps have described the overall geology and geomorphology of the region but have not unraveled the detailed stratigraphy and complex evolution of this unique and geologically diverse martian province. The main purpose of this comprehensive mapping project is to reconstruct the stratigraphic, structural, and erosional histories of the Thaumasia region. The region is the last major province of the Tharsis region to undergo detailed structural mapping using Viking images; its history is essential to documenting the overall tectonic history of Tharsis. Other provinces of Tharsis that have been structurally mapped include Syria Planum (Tanaka and Davis, 1988), Tempe Terra and Ulysses Patera (Scott and Dohm, 1990b), and Alba Patera (Tanaka, 1990). Another primary mapping objective is to determine the region's volcanic history and assess the relations among fault systems and volcanoes (Wise and others, 1979; Scott and Tanaka, 1980; Whitford-Stark, 1982; Scott and Dohm, 1990a). A secondary mapping objective is to determine the distribution and ages of valleys. In our study, we incorporated detailed photogeologic mapping, comprehensive crater statistics (table 1), and geologic, paleotectonic, and paleoerosional Geographic Information System (GIS) databases. Sheets 1–3 show geologic units, faults and other significant structures, and valleys, respectively. To help unravel the complex geologic history of the Thaumasia region, we transferred the highly detailed geologic unit, paleotectonic, and paleoerosional information of sheets 1–3 into a multilayered GIS database for comparative analysis. The geologic information was transferred from hard copy into a digital format by scanning at 25 micron resolution on a drum scanner. The 2-bit scanned image was then converted to an x,y coordinate system using ARC/INFO's vectorization routine. The geologic unit, structural, and erosional data were transformed into the original map projection, Lambert Conformal. The average transformation root mean square error was 0.25 km (acceptable for the Thaumasia map base at 1:5,000,000 scale). After transformation, the features were properly attributed and tediously checked. Once digitized, the map data can be transformed into any map projection depending on the type of data analysis. For example, the equal-area sinusoidal projection was used for determining the precise area of geologic units (table 1). In addition to the geologic map and its attendant stratigraphic section, correlation chart, and description of map units, we include text sections that clarify the histories and temporal, spatial, and causal relations of the various geologic units and landforms of the Thaumasia region. The geologic summary section defines the sequence of major geologic events.

IMAP↗
USGS1998

Operational modeling system with dynamic-wave routing

A near real-time streamflow-simulation system utilizing continuous-simulation rainfall-runoff generation with dynamic-wave routing is being developed by the U.S. Geological Survey in cooperation with the Du Page County Department of Environmental Concerns for a 24-kilometer reach of Salt Creek in Du Page County, Illinois. This system is needed in order to more effectively manage the Elmhurst Quarry Flood Control Facility, an off-line stormwater diversion reservoir located along Salt Creek. Near real time simulation capabilities will enable the testing and evaluation of potential rainfall, diversion, and return-flow scenarios on water-surface elevations along Salt Creek before implementing diversions or return-flows. The climatological inputs for the continuous-simulation rainfall-runoff model, Hydrologic Simulation Program - FORTRAN (HSPF) are obtained by Internet access and from a network of radio-telemetered precipitation gages reporting to a base-station computer. The unit area runoff time series generated from HSPF are the input for the dynamic-wave routing model. Full Equations (FEQ). The Generation and Analysis of Model Simulation Scenarios (GENSCN) interface is used as a pre- and post-processor for managing input data and displaying and managing simulation results. The GENSCN interface includes a variety of graphical and analytical tools for evaluation and quick visualization of the results of operational scenario simulations and thereby makes it possible to obtain the full benefit of the fully distributed dynamic routing results.

Conference Paper↗
USGS2004

Tigers and their prey: Predicting carnivore densities from prey abundance

The goal of ecology is to understand interactions that determine the distribution and abundance of organisms. In principle, ecologists should be able to identify a small number of limiting resources for a species of interest, estimate densities of these resources at different locations across the landscape, and then use these estimates to predict the density of the focal species at these locations. In practice, however, development of functional relationships between abundances of species and their resources has proven extremely difficult, and examples of such predictive ability are very rare. Ecological studies of prey requirements of tigers Panthera tigris led us to develop a simple mechanistic model for predicting tiger density as a function of prey density. We tested our model using data from a landscape-scale long-term (1995-2003) field study that estimated tiger and prey densities in 11 ecologically diverse sites across India. We used field techniques and analytical methods that specifically addressed sampling and detectability, two issues that frequently present problems in macroecological studies of animal populations. Estimated densities of ungulate prey ranged between 5.3 and 63.8 animals per km 2 . Estimated tiger densities (3.2-16.8 tigers per 100 km 2 ) were reasonably consistent with model predictions. The results provide evidence of a functional relationship between abundances of large carnivores and their prey under a wide range of ecological conditions. In addition to generating important insights into carnivore ecology and conservation, the study provides a potentially useful model for the rigorous conduct of macroecological science.

Proceedings of the National Academy of Sciences↗
USGS2025

Assessment of dragonfly and damselfly (Odonata) occupancy and habitat suitability at −12 Mile Slough, Glen Canyon National Recreation Area, Arizona

Management practices that enhance habitat complexity in dam tailwaters often aim to increase biodiversity and improve ecosystem health. However, in other instances, management practices may simplify habitat features to help minimize the establishment of invasive species. These tradeoffs are complex, particularly in the face of drought and warming water temperatures. In Glen Canyon National Recreation Area, a backwater known as −12 Mile Slough (henceforth the Slough), located 5-kilometers downstream from Glen Canyon Dam, is being considered for removal to reduce breeding habitat for warmwater nonnative fishes. In this report, the habitat suitability for and occupancy of dragonflies and damselflies (Odonata) at the Slough are assessed. U.S. Geological Survey staff conducted three site visits to the Colorado River in Glen Canyon, the Slough, and another backwater (“Frogwater”) on September 11–13, and 26, 2024. The physical habitat of the sampling sites was characterized by recording water temperatures, specific conductance, dissolved oxygen, turbidity, flow, depth, and benthic substratum size distribution. We sampled aquatic macroinvertebrates and riparian macroinvertebrates using benthic and aerial collection methods, respectively. We describe three distinct benthic aquatic invertebrate communities in and around the Slough, two of which contained Odonata. We found no Odonata larvae in the mainstem, at Frogwater, or in the Lower Slough. Using historic specimen data from the Museum of Northern Arizona, we report 8 species of damselflies from one family (Coenagrionidae) and 8 species of dragonflies from three families (Aeshnidae, Gomphidae, and Libellulidae) in Glen Canyon between 1985 and 2024. We discuss the habitat requirements of Odonata larvae known to occur in the Slough, as well as their cultural and recreational values. We conclude that channelization of the Slough to cool water temperatures may reduce larval Odonata habitat locally but is unlikely to affect their diversity and abundance on a regional scale.

Arizona↗
USGS2022

The influence of soil development on the depth distribution and structure of soil microbial communities.

Although it has been shown that the interaction of climate and time shape the dynamics of soil organic matter (SOM) storage and preservation in soil, the role of soil microbial communities in this dynamic remains unclear. Microbial communities are present throughout soil profiles and likely play critical roles in SOM and nutrient cycling, however the influence of other factors such as soil development (i.e., age) and the composition SOM on microbial community variation with depth has yet to be quantified. Improving our understanding of the relationship between soil development, soil depth, and microbial communities may provide insight to the critical role they play in cycling and preservation of SOM, as well as more mechanistic predictions of the response of soil communities to change, such as landscape-scale changes in available moisture or temperature regimes. Here we compare soils spanning a soil age by climate gradient (i.e., climo-chronosequence) to better understand the mechanisms which influence soil microbial community structure and the molecular composition of SOM. While we observed little depth-dependence in metrics of microbial community structure (i.e., composition, diversity, dissimilarity) across the range of soil development under a wetter climate, we found significant depth-dependent changes in community metrics under a drier climate, which became more pronounced as soils became older. This shift in bacterial and archaeal community structure and diversity is most apparent below a clay-rich argillic horizon formed in the older, drier soils. The molecular composition of SOM as measured by high resolution mass spectrometry (i.e., FTICR MS) also exhibited similar shifts in composition with soil depth and age. Our results highlight how soil moisture shapes the interaction of soil development, SOM, and microbial community composition. Differences in the moisture regime between our two study sites drives differences in biogeochemical depth gradients and subsequent variation in soil microbes and SOM. This suggests that knowledge of not just the pedogenic trajectory of soil development, but also the spatial position relative to distinct pedogenic features, are important for explaining variations in the depth-dependencies of microbial communities and associated SOM.

California↗
USGS2018

Size, growth, and density data for shallow-water sea urchins from Mexico to the Aleutian Islands, Alaska, 1956–2016

Size, growth, and density have been studied for North American Pacific coast sea urchins Strongylocentrotus purpuratus , S. droebachiensis, S. polyacanthus , Mesocentrotus (Strongylocentrotus) franciscanus , Lytechinus pictus , Centrostephanus coronatus , and Arbacia stellata by various workers at diverse sites and for varying lengths of time from 1956 to present. Numerous peer-reviewed publications have used some of these data but some data have appeared only in graduate theses or the gray literature. There also are data that have never appeared outside original data sheets. Motivation for studies has included fisheries management and environmental monitoring of sewer and power plant outfalls as well as changes associated with disease epidemics. Studies also have focused on kelp restoration, community effects of sea otters, basic sea urchin biology, and monitoring. The data sets presented here are a historical record of size, density, and growth for a common group of marine invertebrates in intertidal and nearshore environments that can be used to test hypotheses concerning future changes associated with fisheries practices, shifts of predator distributions, climate and ecosystem changes, and ocean acidification along the Pacific Coast of North America and islands of the north Pacific.

Pacific Coast↗
USGS2025

Increased heterozygosity and body condition result from admixed translocation of the threatened Mogollon Narrow-headed Gartersnake (Thamnophis rufipunctatus)

Enhancing gene flow through translocations can be a useful tool in recovering small and isolated populations. However, it is not devoid of genetic risks, such as outbreeding depression in future generations, that can have negative consequences in terms of the establishment and mean fitness of the population. Studies that monitor the long-term effects of genetic rescue on populations in the wild are few, especially for snakes. We used long-term genetic monitoring and body condition indices to investigate the consequences of conservation translocation and genetic admixture in a Mogollon Narrow-headed Gartersnake ( Thamnophis rufipunctatus ) wild population. We compared genetic diversity and fitness metrics among the source and recipient populations to evaluate individual- and population-level fitness responses related to the conservation translocation. Our study found persistent captures with continued monitoring for over a decade post-release, and the recipient population showed lower inbreeding values and an increase in heterozygosity that was 19% higher than the two source populations. Snakes sampled in the recipient population had higher individual heterozygosity and body condition than those in the extant source and reference populations. Further, Bayesian regression models supported a significant positive relationship between heterozygosity and body condition after accounting for among-site differences, suggesting that efforts to increase heterozygosity can improve mean fitness in these populations. Our study highlights the potential benefits of conservation translocation from multiple source populations to restore the distribution and increase heterozygosity and population fitness of this threatened gartersnake. Alongside ecological restoration, translocation programs could be used to ensure both the persistence and resilience of populations throughout the species’ range.

New Mexico↗
USGS2016

Uncertainty analysis of the Operational Simplified Surface Energy Balance (SSEBop) model at multiple flux tower sites

Evapotranspiration (ET) is an important component of the water cycle – ET from the land surface returns approximately 60% of the global precipitation back to the atmosphere. ET also plays an important role in energy transport among the biosphere, atmosphere, and hydrosphere. Current regional to global and daily to annual ET estimation relies mainly on surface energy balance (SEB) ET models or statistical and empirical methods driven by remote sensing data and various climatological databases. These models have uncertainties due to inevitable input errors, poorly defined parameters, and inadequate model structures. The eddy covariance measurements on water, energy, and carbon fluxes at the AmeriFlux tower sites provide an opportunity to assess the ET modeling uncertainties. In this study, we focused on uncertainty analysis of the Operational Simplified Surface Energy Balance (SSEBop) model for ET estimation at multiple AmeriFlux tower sites with diverse land cover characteristics and climatic conditions. The 8-day composite 1-km MODerate resolution Imaging Spectroradiometer (MODIS) land surface temperature (LST) was used as input land surface temperature for the SSEBop algorithms. The other input data were taken from the AmeriFlux database. Results of statistical analysis indicated that the SSEBop model performed well in estimating ET with an R2 of 0.86 between estimated ET and eddy covariance measurements at 42 AmeriFlux tower sites during 2001–2007. It was encouraging to see that the best performance was observed for croplands, where R2 was 0.92 with a root mean square error of 13 mm/month. The uncertainties or random errors from input variables and parameters of the SSEBop model led to monthly ET estimates with relative errors less than 20% across multiple flux tower sites distributed across different biomes. This uncertainty of the SSEBop model lies within the error range of other SEB models, suggesting systematic error or bias of the SSEBop model is within the normal range. This finding implies that the simplified parameterization of the SSEBop model did not significantly affect the accuracy of the ET estimate while increasing the ease of model setup for operational applications. The sensitivity analysis indicated that the SSEBop model is most sensitive to input variables, land surface temperature (LST) and reference ET ( ET o ); and parameters, differential temperature ( dT ), and maximum ET scalar ( K max ), particularly during the non-growing season and in dry areas. In summary, the uncertainty assessment verifies that the SSEBop model is a reliable and robust method for large-area ET estimation. The SSEBop model estimates can be further improved by reducing errors in two input variables ( ET o and LST) and two key parameters ( K max and dT ).

Journal of Hydrology↗