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USGS2005

The role of pH in structuring communities of Maine wetland macrophytes and chironomid larvae (Diptera)

Aquatic vascular plants, or macrophytes, are an important habitat component for many wetland organisms, and larvae of chironomid midges are ubiquitous components of wetland fauna. Many chironomids are primary consumers of algae and detritus and form an essential energetic link between allochthonous and autochthonous primary production and higher trophic levels, while others are predators and feed on smaller invertebrates. Live macrophytes serve mostly as habitat, whereas plant detritus serves as both habitat and as a food source. Assemblages of macrophytes and chrinomid larvae were surveyed in ten Maine wetlands, five with low pH (<5.0) and five with high pH (>5.5), and explained in terms of physical and chemical habitat variables. Macrophyte richness was significantly greater, and richness of chironomid larvae was lower, in low pH wetlands. There was no difference in chironomid abundance related to pH. However, community structure was related to pH, suggesting that competitive dominance of a few taxa was responsible for lower richness in low pH wetlands, whereas competition was weaker in high pH wetlands, making coexistence of more chironomid taxa possible. An examination of individual chironomid taxa by stepwise multiple regression showed that distribution of most taxa was controlled by water chemistry variables and macrophyte habit (i.e., floating, submergent).

Maine↗

USGS1999

Effects of saline drinking water on early gosling development

Relatively high levels of saline drinking water may adversely affect the growth, development, and survival of young waterfowl. Saline drinking water was suspect in the low survival rate of Canada goose (Branta canadensis) goslings at Fish Springs National Wildlife Refuge (FSNWR) in western Utah. Hence, we investigated the effects of saline drinking water on the survival and growth of captive, wild-strain goslings from day 1-28 following hatch. We compared survival and growth (as measured by body mass, wing length, and culmen length) between a control group on tap water with a mean specific conductivity of 650 μS/cm, and 2 saline water treatments: (1) intermediate level (12,000 μS/cm), and (2) high level (18,000 μS/cm). Gosling mortality occurred only in the 18,000 μS/cm treatment group (33%; n = 9). Slopes of regressions of mean body mass, wing length, and culmen length on age were different from each other (P < 0.05), except for culmen length for the intermediate and high treatment levels. We predict that free-ranging wild goslings will experience mortality at even lower salinity levels than captive goslings because of the combined effects of depressed growth and environmental stresses, including hot desert temperatures and variable food quality over summer.

Journal of Wildlife Management↗

USGS2021

A desert tortoise-common raven viable conflict threshold

Since 1966, common raven ( Corvus corax ; raven) abundance has increased throughout much of this species’ Holarctic distribution, fueled by an ever-expanding supply of anthropogenic resource subsidies (e.g., water, food, shelter, and nesting substrate) to ecoregion specific raven population carrying capacities. Consequently, ravens are implicated in declines of both avian and reptilian species of conservation concern, including the California (USA) endangered and federally threatened Mojave desert tortoise ( Gopherus agassizii ; desert tortoise). While ravens are a natural predator of desert tortoises, the inter-generational stability of desert tortoise populations is expected to be compromised as annual juvenile survival is suppressed below 0.77 through a combination of raven depredation and other sources of mortality. To estimate the extent to which raven depredation suppresses desert tortoise recruitment within the Mojave Desert of California, we collected data from 274 variable-radius point counts, 78 desert tortoise decoy stations, and 8 control stations during the spring of 2020. Additionally, we complied a geodatabase of previously active raven nests, observed between 2013 and 2020. Raven density estimates from 4 monitoring areas ranged between 0.63 (eastern most) and 2.44 (western most) raven km -2 (95% CI: 0.35–1.14 and 1.33–4.48, respectively). We used a Bayesian shared frailty model to estimate the effects of raven density and distance to the nearest previously active raven nest on the annual “survival” of juvenile desert tortoise decoys (75-mm Midline Carapace Length), which we then converted into survival estimates for 0- to 10-year-old desert tortoises by adjusting exposure to reflect natural activity patterns. At the 1.72-km median distance from the nearest previously active raven nest, the estimated annual survival of desert tortoises decreased as raven density increased, ranging among conservation areas from 0.774 (eastern most) to 0.733 (western most). Accordingly, our model predicts that desert tortoise populations exposed to raven densities in excess of 0.89 raven km -2 , at a distance

California↗

USGS2010

A climate trend analysis of Kenya-August 2010

Introduction This brief report draws from a multi-year effort by the United States Agency for International Development's Famine Early Warning System Network (FEWS NET) to monitor and map rainfall and temperature trends over the last 50 years (1960-2009) in Kenya. Observations from seventy rainfall gauges and seventeen air temperature stations were analyzed for the long rains period, corresponding to March through June (MAMJ). The data were quality controlled, converted into 1960-2009 trend estimates, and interpolated using a rigorous geo-statistical technique (kriging). Kriging produces standard error estimates, and these can be used to assess the relative spatial accuracy of the identified trends. Dividing the trends by the associated errors allows us to identify the relative certainty of our estimates (Funk and others, 2005; Verdin and others, 2005; Brown and Funk, 2008; Funk and Verdin, 2009). Assuming that the same observed trends persist, regardless of whether or not these changes are due to anthropogenic or natural cyclical causes, these results can be extended to 2025, providing critical, and heretofore missing information about the types and locations of adaptation efforts that may be required to improve food security.

Fact Sheet↗

USGS2022

In situ soil moisture sensors in undisturbed soils

Soil moisture directly affects operational hydrology, food security, ecosystem services, and the climate system. However, the adoption of soil moisture data has been slow due to inconsistent data collection, poor standardization, and typically short record duration. Soil moisture, or quantitatively volumetric soil water content (SWC), is measured using buried, in situ sensors that infer SWC from an electromagnetic response. This signal can vary considerably with local site conditions such as clay content and mineralogy, soil salinity or bulk electrical conductivity, and soil temperature; each of these can have varying impacts depending on the sensor technology., Furthermore, poor soil contact and sensor degradation can affect the quality of these readings over time. Unlike more traditional environmental sensors, there are no accepted standards, maintenance practices, or quality controls for SWC data. As such, SWC is a challenging measurement for many environmental monitoring networks to implement. Here, we attempt to establish a community-based standard of practice for in situ SWC sensors so that future research and applications have consistent guidance on site selection, sensor installation, data interpretation, and long-term maintenance of monitoring stations., The videography focuses on a multi-agency consensus of best-practices and recommendations for the installation of in situ SWC sensors. This paper presents an overview of this protocol along with the various steps essential for high-quality and long-term SWC data collection. This protocol will be of use to scientists and engineers hoping to deploy a single station or an entire network.

Journal of Visualized Experiments↗

USGS2010

Methylmercury cycling, bioaccumulation, and export from agricultural and non-agricultural wetlands in the Yolo Bypass

This 18-month field study addresses the seasonal and spatial patterns and processes controlling methylmercury (MeHg) production, bioaccumulation, and export from natural and agricultural wetlands of the Yolo Bypass Wildlife Area (YBWA). The data were collected in conjuntion with a Proposition 40 grant from the State Water Resources Control Board in support of the development of Best Management Practices (BMP's) for reducing MeHg loading from agricultural lands in the wetland-dominated Yolo Bypass to the Sacramento-San Joaquin River Delta. The four managemenr-based questions addressed in this study were: 1. Is there a different among agricultural and managfed wetland types in terms of Me Hg dynamic (production, degradation, bioaccumulation, or export)? 2. Does water residence time influence MeHg dynamics? 3. Does the application of sulfate-based fertilizer impact MeHg production rates? 4. Does the presence (or absence) of vegetation influence MeHg production rates? Measurements of MeHg concentrations in sediment, water, and biota (plants, invertebrates, and fish) were made to assess management-level patterns in five wetland types, which included three type of shallowly-flooded agricultural wetlands (white rice, wild rice, and fallow) and two types of managed wetlands (permanently and seasonally flooded). To strengthen our understanding of the processes underlying the seasonal and spatial patterns of MeHg cycling, additional exploratory factors were measured including ancillary sediment and water quality parameters, stable isotope fractionation (oxygen, sulfur, carbon, and nitrogen), photodemethylation rates, and daily-integrated hydrologic budgets. Samples and field data were collected from May 2007 to July 2008, and nearly all sample analyses were completed by September 2008 as per the Quality Assurance Program Plan (QAPP) requirements. Although wetland type was a major factor that drove the study design, within-field hydrology also proved to be an important factor controlling aqueous MeHg and total mercury (THg) concentrations and export. Overall, agricultural wetlands exhibited higher MeHg concentrations in overlying water, sediment, and biota than did managed seasonal and permanent wetlands. This appears to be partly due to higher rates of sediment in microbial production of MeHg on agricultural wetlands during the fall through spring period. Both sulfate- and iron-reducing bacteria have been implicated in the MeHg production process, and both were demonstrably active in all wetlands studied; however, sulfate-reducing bacteria were not stimulated by the addition of sulfate-based fertilizer to agricultural wetlands, suggesting that easily-degraded (labile) organic matter, rather than sulfate, was limiting their activity in these field types. The data suggest that agriculturally-managed soils promoted MeHg production through 1) enhanced microbial activity via higher temperatures and larger pools of labile carbon, and 2) enhanced pools of microbially available inorganic divalent mercury (Hg(II)) resulting from a decrease in reduced-sulfur, solid-phase minerals under oxic or only mildly reducing conditions. MeHg mass balances were assessed by comparing filed-specific MeHg loads for inlets vs. outlet flows. The overall mass balance for MeHg in surface water during the summer irrigation period (June - September 2007) indicated little to no net MeHg export from the six agricultural wetlands taken as a whole. Of the six agricultural wetlands, there was net overall MeHg export from two fields (one fallow and one white rice) during August, and from four of the six fields (one fallow, one white rice, and two wild rice) during September) Over the entire summer irrigation period, two of the fields (one fallow and one wild rive) showed net MeHg export, and the other four fields showed wither net import or no significant change. Rates of measured photomethylation and exchange between sediment and water pools suggest that both processes may be responsible for the lack of MeHg export. Despite significant differences during winter months between fields in surface water concentrations of MeHg, MeHg loads were not calculated in mid-winter because flood waters had overtopped field boundaries and field fidelity could not be established. During the summer 2007 irrigation season, surface water out-flows from agricultural wetlands were 9%-36% of inlet flows, and evaporation rates explained most of this water loss, with infiltration likely accounting for the remainder. Unfiltered aqueous MeHg concentrations increased from <1 ng L -1 in source waters to up to 10 ng L -1 in agricultural wetland drains during the summer irrigation period. Increases in solute concentration caused by evapoconcentration were estimated by determining concentration factors (outflow/inflow) for chloride (a conservative dissolved constituent) and by measuring oxygen isotope ratios ( 18 O/ 16 O, expressed as δ 18 O) in water. Increases in MeHg concentration from inflows-to-outflows exceeded those caused by evapoconcentration on several fields during the summer irrigation season. This was especially true when initial surface water MeHg concentrations were low, as seen in the southern block of fields receiving irrigation water directly from the Toe Drain. The northern block of fields received irrigation water from Greens Lake, which included Toe Drain water plus recirculated drain water from other agricultural fields within the Yolo Bypass and west of the Yolo Bypass; as such, the northern fields showed a smaller percentage increase in MeHg concentration because initial MeHg concentrations in surface water inflows were greater than in inputs to the southern fields. Mercury concentrations in fish were greater in agricultural wetlands white rice and wild rice) than in the two permanently flooded wetlands. Additionally, Hg concentrations in biota showed a general increase from inlets to outlets withing agricultural wetlands, but not within permanent wetlands. This was particular evident in white rice fields where caged western mosquitofish at the outlets had Hg concentrations that were more than 4 times higher than in caged fish held at the inlets. Similar spatial patterns in Hg bioaccumulation in agricultural and permanent wetlands were seen for wild populations of western mosquitofish and Mississippi silversides. In contrast to fish, invertebrates, such as water-boatman (Corixidae) and back swimmers (Notonectidae), had greater Hg concentrations in permanent wetlands than in tempoarirly flooded agricultural wetlands, Fish THg concentrations were weakly correlated with water MeHg,a and not correlated with sediment MeHg. In contrast, invertebrate MeHg concentrations were more strongly correlated with sediment MeHg than with water MeHg concentrations. These results illustrate the complexity of MeHg bioaccumulation through food webs and indicate the importance of simultaneously using multiple biosentinels when monitoring MeHg production and bioaccumulation. Despite high sediment production rates and water concentrations in agricultural wetlands, MeHg export was physically limited by hydrologic export for all wetlands studied. We suggest that load reduction is maximized by limiting water throughout, but that on-site biota exposure is maximized by this loner water residence time. While field-specific hydrologic loads could not be fully quantified during flood conditions in February 2008, we suggest that the primary period of MeHg export from Yolo Bypass Wildlife Area is during those winter flooding periods when overall microbial activity and MeHg production in agricultural soils is fueled by the decomposition of rice straw, and when hydrologic flowthrough is maximal. Local stakeholders participated in two workshops related to this study, demonstrating an interest in understanding factors controlling MeHg production, export, and bioaccumulation. The results of this field study show that permanently flooded, naturally vegetated wetlands are unlikely to a large source of MeHg production within the YBWA, in contrast with agriculturally-managed wetlands. MeHg loading to Toe Drain waters of the Yolo Bypass may be reduced by lowering rated of hydrologic export from agricultural wetlands during the growing season and especially during rice harvest, However, under these water-holding conditions, biota living within agricultural wetlands may thus be exposed to higher MeHg concentrations in surface water, As observed in this study, rapid bioacculumaltion over a 2-month period led to MeHg concentrations in invertebrates and fish more than 6 and 11 times higher, respectively, than proposed TMDL target values to protect wildlife (0.03 ppm ww). The results of this field study, together with the information from YBWA stakeholders, provide a more definitive understanding of how MeHg cycling and bioaccumulation respond to habitat differences and specific management practices. These results directly address 4 core components of CBDA's Mercury Strategy for the Bay-Delta Ecosystem (Wiener et al., 2003a): a) Quantification and evaluation of THg and MeHg sources, b) Quantification of effects of ecosystem restoration on MeHg exposure, c) Assessment of ecological risk, and d) Identification and testing of potential management approaches for reducing MeHg contamination. In addition, the quantitative results reported here assess the effect of current land use practices in the Yolo Bypass MeHg production, bioaccumulation and export, and provide process-based advice towards achieving current goals of the RWQCB-CVR's Sacramento -- San Joaquin Delta Estuary TMDL for Methyl & Total Mercury (Wood et al., 2010b). Further work is necessary to evaluate biotic exposure in the Yolo Bypass Wildlife Area at higher trophic levels (e.g. birds), to quantify winter hydrologic flux of MeHg to the larger Delta ecosystem, and to evaluate rice straw management options to limit labile carbon supplies to surface sediment during winter months. In summary, agricultural management of rice fields -- specifically the periodic flooding and production of easily degraded organic matter -- promotes the production of MeHg beyond rates seen in naturally vegetated wetlands, whether seasonally or permanently flooded., The exported load from MeHg from these agricultural wetlands may be controlled by limiting hydrologic export from fields to enhance on-site MeHg removal processes, but the tradeoff is that this impoundement increases Me Hg exposure to resident organisms.

California↗

USGS2018

Mercury methylation and bioaccumulation in Sinclair Inlet, Kitsap County, Washington

The U.S. Geological Survey evaluated the transformation of mercury to bioavailable methylmercury in Sinclair Inlet, Kitsap County, Washington, and assessed the effect of the transformation processes on the mercury burden in marine organisms and sediment. In August 2008, samples of sediment, water, and biota from six sites in Sinclair Inlet and three bays representative of Puget Sound embayments were collected. The extensive sediment sampling included analysis of methylmercury in sediment and porewater, estimates of methylation production potential, and analyses of ancillary constituents associated with organic carbon and reduction-oxidation (redox) conditions to assist in interpreting the mercury results. Analyses of methylmercury in water overlying incubated cores provided an estimate of the release of methylmercury to the water column. Collection of samples for mercury species in the aqueous, particulate (suspended solids), and biological phases, and for ancillary carbon and nitrogen constituents in surface water, continued, on about a monthly schedule, at four stations through August 2009. In February, June, and August 2009, seasonal sediment samples were collected at 20 stations distributed between greater Sinclair Inlet and Operable Unit B Marine of the Bremerton naval complex, Bremerton, Washington, to examine geographical and seasonal patterns of mercury biogeochemistry of sediment in Sinclair Inlet. At six of these seasonal sediment stations, porewater was collected and triplicate core incubation experiments were done. Median sediment-methylmercury concentrations were not statistically different between the representative bays and Sinclair Inlet. The percentage of sediment methylmercury (relative to total mercury) was actually lower in the Sinclair Inlet sites compared with the representative bays, reflecting the higher sediment total mercury concentration for the Sinclair Inlet stations compared with the representative bays. Likewise, median sediment methylmercury concentrations were not statistically different between the greater Sinclair Inlet stations and the Bremerton naval complex stations; whereas the percentage of sediment methylmercury to total mercury was lower in the Bremerton naval complex due to higher sediment total mercury concentrations than the greater Sinclair Inlet stations. The biogeochemical characteristics of each station, measured by redox, organic carbon, and the seasonal availability of nutrients controlled methylmercury biogeochemistry. Mercury methylation production potential was a function of temperature, concentration of total mercury in sediment, and the percentage of ferrous iron (relative to total measured iron) across all sites. Methylmercury porewater concentrations were best described by using concentrations of dissolved organic carbon and reduction-oxidation conditions. Likewise, the variable fluxes of methylmercury from incubated cores were best described using dissolved organic carbon and reduction-oxidation conditions. Sinclair Inlet exhibited the classic Puget Sound biological cycle, with spring and autumn phytoplankton blooms resulting in depletion of nitrate, orthophosphate, and silicate in the surface water. Although variable in timing between 2008 and 2009, a strong corresponding seasonal trend of increased availability, incorporation, and bioaccumulation of methylmercury into the food web of Sinclair Inlet occurred during the early spring and summer growing season.

Washington↗

USGS2012

Geochemical modeling of changes in shallow groundwater chemistry observed during the MSU-ZERT CO2 injection experiment

A field experiment involving the release of carbon dioxide (CO 2 ) into a shallow aquifer was conducted near Bozeman, Montana, during the summer of 2008, to investigate the potential groundwater quality impacts in the case of leakage of CO 2 from deep geological storage. As an essential part of the Montana State University Zero Emission Research and Technology (MSU-ZERT) field program, food-grade CO 2 was injected over a 30 day period into a horizontal perforated pipe a few feet below the water table of a shallow aquifer. The impact of elevated CO 2 concentrations on groundwater quality was investigated by analyzing water samples taken before, during, and following CO 2 injection, from observation wells located in the vicinity of the injection pipe, and from two distant monitoring wells. Field measurements and laboratory analyses showed rapid and systematic changes in pH, alkalinity, and conductance, as well as increases in the aqueous concentrations of naturally occurring major and trace element species. The geochemical data were evaluated using principal component analysis (PCA) to (1) understand potential correlations between aqueous species, and (2) to identify minerals controlling the chemical composition of the groundwater prior to CO 2 injection. These evaluations were used to assess possible geochemical processes responsible for the observed increases in the concentrations of dissolved constituents, and to simulate these processes using a multicomponent reaction path model. Reasonable agreement between observed and modeled data suggests that (1) calcite dissolution was the primary pH buffer, yielding increased Ca +2 concentrations in the groundwater, (2) increases in the concentrations of most major and trace metal cations except Fe could be a result of Ca +2 -driven exchange reactions, (3) the release of anions from adsorption sites due to competitive adsorption of carbonate could explain the observed trends of most anions, and (4) the dissolution of reactive Fe minerals (presumed ferrihydrite and fougerite, from thermodynamic analyses) could explain increases in total Fe concentration. Highlights ► Because the possibility of CO 2 leakage cannot be completely ruled out, the potential impact of CO 2 intrusion on the quality of fresh water aquifers overlying CO 2 storage sites needs to be investigated. ► Geochemical data from a field experiment involving the release of carbon dioxide (CO 2 ) into a shallow aquifer were evaluated. ► Geochemical model used to assess possible geochemical processes responsible for the observed increases in the concentrations of dissolved constituents. ► Reasonable agreement between observed and modeled data suggests that increases in the concentrations of most major and trace metal cations except Fe could be a result of Ca +2 -driven exchange reactions and the release of anions from adsorption sites due to competitive adsorption of carbonate could explain the observed trends of most anions.

Montana↗

USGS2024

Larval Lake Whitefish (Coregonus clupeaformis) zooplankton consumption remains constant despite variation in prey densities in western Lake Erie

Larval fish growth and survival could be limited or reduced due to patchiness of zooplankton densities, even in productive aquatic systems. Recent declines in Lake Whitefish ( Coregonus clupeaformis ) populations prompted research to identify underlying mechanisms controlling survival at early life stages. In Lake Erie, the bottleneck window controlling year-class strength of Lake Whitefish likely occurs during the first growing season, suggesting that availability of important prey could influence year-class strength. Therefore, spatial and temporal larval Lake Whitefish distribution, diet, and prey utilization were evaluated in western Lake Erie. The pelagic Lake Whitefish larval period in the western basin extends from April 1 to May 15 with most larvae concentrated nearshore at the surface both day and night. Cyclopoid copepods were the most important prey item; however, calanoid copepods and Cladocera were consistently consumed, indicating that copepods and Cladocera were important larval Lake Whitefish prey items. Copepod and Cladocera biomass were the highest nearshore, overlapping with the highest larval Lake Whitefish densities. However, the amount of food consumed by larvae was consistent in all areas, suggesting that offshore areas in western Lake Erie with relatively low zooplankton biomass harbor enough food to satiate larval Lake Whitefish. Therefore, it is unlikely that prey availability limits survival through means of starvation during the larval phase.

western Lake Erie↗

USGS2018

Common hydraulic fracturing fluid additives alter the structure and function of anaerobic microbial communities

The development of unconventional oil and gas (UOG) resources results in the production of large volumes of wastewater containing a complex mixture of hydraulic fracturing chemical additives and components from the formation. The release of these wastewaters into the environment poses potential risks that are poorly understood. Microbial communities in stream sediments form the base of the food chain and may serve as sentinels for changes in stream health. Iron-reducing organisms have been shown to play a role in the biodegradation of a wide range of organic compounds, and so to evaluate their response to UOG wastewater, we enriched anaerobic microbial communities from sediments collected upstream (background) and downstream (impacted) of an UOG wastewater injection disposal facility in the presence of hydraulic fracturing fluid (HFF) additives: guar gum, ethylene glycol, and two biocides, 2,2-dibromo-3-nitrilopropionamide (DBNPA) and bronopol (C 3 H 6 BrNO 4 ). Iron reduction was significantly inhibited early in the incubations with the addition of biocides, whereas amendment with guar gum and ethylene glycol stimulated iron reduction relative to levels in the unamended controls. Changes in the microbial community structure were observed across all treatments, indicating the potential for even small amounts of UOG wastewater components to influence natural microbial processes. The microbial community structure differed between enrichments with background and impacted sediments, suggesting that impacted sediments may have been preconditioned by exposure to wastewater. These experiments demonstrated the potential for biocides to significantly decrease iron reduction rates immediately following a spill and demonstrated how microbial communities previously exposed to UOG wastewater may be more resilient to additional spills.

Applied and Environmental Microbiology↗

USGS2000

Geologic map of the upper Parashant Canyon and vicinity Mohave County, northwestern Arizona

The geologic map of the upper Parashant Canyon area covers part of the Colorado Plateau and several large tributary canyons that make up the western part of Arizona's Grand Canyon. The map is part of a cooperative U.S. Geological Survey and National Park Service project to provide geologic information for areas within the newly established Grand Canyon/Parashant Canyon National Monument. Most of the Grand Canyon and parts of the adjacent plateaus have been geologically mapped; this map fills in one of the remaining areas where uniform quality geologic mapping was needed. The geologic information presented may be useful in future related studies as to land use management, range management, and flood control programs for federal and state agencies, and private concerns. The map area is in a remote region of the Arizona Strip, northwestern Arizona about 88 km south of the nearest settlement of St. George, Utah. Elevations range from about 1,097 m (3,600 ft) in Parashant Canyon (south edge of map area) to 2,145 m (7,037 ft) near the east-central edge of the map area. Primary vehicle access is by dirt road locally known as the Mount Trumbull road; unimproved dirt roads and jeep trails traverse various parts of the map area. Travel on the Mount Trumbull road is possible with 2-wheel-drive vehicles except during wet conditions. Extra fuel, two spare tires and extra food and water are highly recommended when traveling in this remote area. The map area includes about 26 sections of land belonging to the State of Arizona, about 40 sections of private land, and a small strip of the Lake Mead National Recreation Area (southeast edge of the map area). The private land is mainly clustered around the abandoned settlement of Mt. Trumbull, locally known as Bundyville, and a few sections are scattered in the upper Whitmore Canyon area just south of Bundyville. Lower elevations within the canyons support a sparse growth of sagebrush, cactus, grass, creosote bush, and a variety of desert shrubs. Sagebrush, grass, cactus, cliffrose bush, pinyon pine trees, juniper trees, and some ponderosa pines thrive at higher elevations. Surface runoff in the north half of the map area drains northward towards the Virgin River in Utah via Hurricane Wash. In the south half of the area, it drains towards the Colorado River in Grand Canyon via Parashant and Whitmore Canyons. Upper Parashant and Whitmore Canyons are part of the physiography of the western Grand Canyon, but are not included within Grand Canyon National Park. The entire map area is now within the newly established Grand Canyon/Parashant Canyon National Monument (as of January, 2000), and is jointly managed by the Lake Mead National Recreational Area, Boulder City, Nevada, and the Bureau of Land Management, Arizona Strip District, St. George, Utah. Surface runoff in the north half of the map area drains northward towards the Virgin River in Utah via Hurricane Wash. In the south half of the area, it drains towards the Colorado River in Grand Canyon via Parashant and Whitmore Canyons. Upper Parashant and Whitmore Canyons are part of the physiography of the western Grand Canyon, but are not included within Grand Canyon National Park. The entire map area is now within the newly established Grand Canyon/Parashant Canyon National Monument (January, 2000), and is jointly managed by the Lake Mead National Recreational Area, Boulder City, Nevada, and the Bureau of Land Management, Arizona Strip District, St. George, Utah.

Arizona↗

USGS2001

Cruise Report; RV Moana Wave cruise M1-01-GM; the bathymetry and acoustic backscatter of the mid shelf to upper slope off Panama City, Florida, northeastern Gulf of Mexico; September 3, through October 12, 2001, Panama City, FL to Panama City, FL

A zone of deep-water reefs is thought to extend from the mid and outer shelf south of Mississippi and Alabama to at least the northwestern Florida shelf off Panama City, Florida (Figure 1, 67kb). The reefs off Mississippi and Alabama are found in water depths of 60 to 120 m (Ludwick and Walton, 1957; Gardner et al., in press) and were the focus of a multibeam echosounder (MBES) mapping survey by the U.S. Geological Survey (USGS) in 2000 (Gardner et al., 2000; in press). If this deep-water-reef trend does exist along the northwestern Florida shelf, then it is critical to determine the accurate geomorphology and type of the reefs that occur because of their importance as benthic habitats for fisheries. Precisely georeferenced high-resolution mapping of bathymetry is a fundamental first step in the study of areas suspected to be critical habitats. Morphology is thought to be critical to defining the distribution of dominant demersal plankton/planktivores communities. Fish faunas of shallow hermatypic reefs have been well studied, but those of deep ahermatypic reefs have been relatively ignored. The ecology of deep-water ahermatypic reefs is fundamentally different from hermatypic reefs because autochthonous intracellular symbiotic zooxanthellae (the carbon source for hermatypic corals) do not form the base of the trophic web in ahermatypic reefs. Instead, exogenous plankton, transported to the reef by currents, serves as the primary carbon source. Thus, one of the principle uses of the morphology data will be to identify whether any reefs found are hermatypic or ahermatypic in origin. Community structure and trophodynamics of demersal fishes of the outer continental of the northeastern Gulf of Mexico presently are the focus of a major USGS reseach project. A goal of the project is to answer questions concerning the relative roles played by morphology and surficial geology in controling biological differentiation. Deep-water reefs are important because they are fish havens, key spawning sites, and are critical early larval and juvenile habitats for economically important sport/food fishes. It is known that deep-water reefs function as a key source for re-population (via seasonal and ontogenetic migration) of heavily impacted inshore reefs. The deep-water reefs south of Mississippi and Alabama support a lush fauna of ahermatypic hard corals, soft corals, black corals, sessile crinoids and sponges, that together form a living habitat for a well-developed fish fauna. The fish fauna comprises typical Caribbean reef fishes and Carolinian shelf fishes, plus epipelagic fishes, and a few deep-sea fishes. The base of the megafaunal invertebrate food web is plankton, borne by essentially continuous semi-laminar currents generated by eddies, spawned off the Loop Current, that periodically travel across the shelf edge. A few, sidescan-sonar surveys have been made of areas locally identified as Destin Pinnacles, Steamboat Lumps Marine Reserve (Koenig et al., 2000; Scanlon, et al., 2000; 2001), Twin Ridges (Briere, et al., 2000; Scanlon, et al., 2000), and Madison-Swanson Marine Reserve (Koenig et al., 2000; Scanlon, et al., 2000; 2001). However, no quantitative and little qualitative information about the geomorphology and surficial geology can be gained from these data. Existing bathymetry along the northwestern Florida shelf suggests the existence of areas of possible isolated deep-water reefs. NOAA bathymetric maps NOS NH16-9 and NG16-12 show geomorphic expressions that hint of the presence of reefs in isolated areas rather than in a continuous zone. There has been no systematic, high-resolution bathymetry collected in this area, prior to this cruise. After the successful mapping of the deep-water reefs on the Mississippi and Alabama shelf (Gardner et al., 2000; in press), a partnership composed of the USGS, Minerals Management Service, and NOAA was formed to continue the deep-reef mapping to the northwest Florida mid shelf and upper slope. This cruise is the first fruit of that partnership.

Florida↗

USGS2012

Effects of a drawdown on plant communities in a freshwater impoundment at Lacassine National Wildlife Refuge, Louisiana

Disturbance is an important natural process in the creation and maintenance of wetlands. Water depth manipulation and prescribed fire are two types of disturbance commonly used by humans to influence vegetation succession and composition in wetlands with the intention of improving wildlife habitat value. A 6,475-hectare (ha) impoundment was constructed in 1943 on Lacassine National Wildlife Refuge in southwest Louisiana to create freshwater wetlands as wintering waterfowl habitat. Ten years after construction of the impoundment, called Lacassine pool, was completed, refuge staff began expressing concerns about increasing emergent vegetation cover, organic matter accumulation, and decreasing area of open water within the pool. Because the presence of permanent standing water impedes actions that can address these concerns, a small impoundment within the pool where it was possible to manipulate water depth was created. The 283-ha subimpoundment called Unit D was constructed in 1989. Water was pumped from Unit D in 1990, and the unit was permanently reflooded about 3 years later. Four prescribed fires were applied during the drawdown. A study was initiated in 1990 to investigate the effect of the experimental drawdown on vegetation and soils in Unit D. Four plant community types were described, and cores were collected to measure the depth of the soil organic layer. A second study of Unit D was conducted in 1997, 4 years after the unit was reflooded, by using the same plots and similar sampling methods. This report presents an analysis and synthesis of the data from the two studies and provides an evaluation of the impact of the management techniques applied. We found that plant community characteristics often differed among the four communities and varied with time. Species richness increased in two of the communities, and total aboveground biomass increased in all four during the drawdown. These changes, however, did not persist when Unit D was reflooded; by 1997, species richness and aboveground biomass were equivalent to values before the drawdown. The change in waterfowl food value of the plant communities during the drawdown varied; it did not change in two communities, increased in one, and decreased in one. A consistent pattern noted was that waterfowl food value was higher in communities that contained open water than in those dominated by emergent plants, both soon after the drawdown was initiated in Unit D and 4 years after reflooding. A reduction in depth of the soil organic layer became apparent 20 months after drawdown was initiated, and this reduction persisted in 1997, 4 years after reflooding. A separate 2003 study on soil characteristics in Lacassine pool found that the depth to the clay layer was lower in Unit D than in the rest of the pool. We were not able to establish a cause-and-effect relation between any changes noted and the fact water levels in the unit were drawn down because the initial study in 1990 did not include control plots. Changes in vegetation and soil organic layer depth identified in Unit D may have occurred in the surrounding Lacassine pool habitat as well. Similarly, we were unable to form any conclusions about the effect of the prescribed fire treatments because there was no information on which plots were burned. Because of the known relation between anaerobic soil conditions and reduced decomposition of organic matter, however, it is likely that the drawdown in Unit D resulted in an increased decomposition rate and a reduction in the depth of the soil organic layer.

Louisiana↗

USGS1980

Toxicity of five forest insecticides to cutthroat trout and two species of aquatic invertebrates

The Northern Rocky Mountain region has had scattered infestation of the western spruce budworm Christoneura occidentalis since the early 1900's (U.S. DEPARTMENT OF AGRICULTURE (USDA) 1976b). On the basis of aerial surveys in 1975, TUNNOCK et al. (1976), estimated that budworm defoliation occurred on 2,278,804 acres of six National Forests in Montana. Since the use of DDT was banned in 1972, there has been a need to develop alternative insecticides with the efficacy of DDT but without its environmental risk. These insecticides must be effective in controlling the budworm, but should not persist in the environment or be toxic to other organisms. The organophosphate and carbamate insecticides are relatively nonpersistent and generally present only a moderate hazard to fish when applied according to label recommendations. The USDA Forest Service has been investigating the effectiveness of these two classes of insecticides against the budworm, and the Columbia National Fisheries Research Laboratory of the U.S. Fish and Wildlife Service has been cooperating with the Forest Service conducted pilot control projects in eastern Montana in 1975 and 1976 to determine the efficacy and environmental impact of acephate, carbaryl, and trichlorfon in controlling the western budworm (USDA 1976 b). In 1975, a similar type project was carried out in Maine with aminocarb, fenitrothion, and trichlorfon (USDA 1976 a). Acephate, fenitrothion, and trichlorfon (organophosphate insecticides) and aminocarb and carbaryl (carbamate insecticides) were selected for toxicity tests against cutthroat trout ( Salmo clarki ), a stonefly ( Pteronarcella badia ), and a freshwater amphipod ( Gammarus pseudolimnaeus ) edemic in streams of the northern Rocky Mountains. Populations of cutthroat trout inhabit lakes and streams in the Rocky Mountains which include some of the most pristine habitat and fisheries in North America. Pteronarcella and Gammarus provide forage for cutthroat trout and feed on decaying vegetation in riffle areas in streams and rivers. Stonefly naiads and amphipods were selected as test organisms because of their importance as trout food and their wide distribution in mountain stream communities. We determined the effect of various water types representing different biogeographical areas in the Intermountain West on the toxicity of these five forest insecticides.

Bulletin of Environmental Contamination and Toxico↗

USGS2025

Quantitative subsurface characterization illuminates the origin of the Quaternary Mississippi River Valley alluvial aquifer

The Mississippi River Valley alluvial aquifer (MRVA) is vital to U.S. food security and global agricultural supply. However, quantitative understanding of its Quaternary origin, architecture, and hydrologic function remains incomplete. Here we develop a three-dimensional hydrostratigraphic model to characterize the deposition of clay and silt, fine-medium sands, and graveliferous sands using lithologic data from 75,000 boreholes compiled across the Lower Mississippi Valley and a geostatistical method—interval kriging. We find that cyclic glacial entrenchments, evidenced by remnants of pre-Wisconsinan postglacial sediments, alongside geodynamic activities shaped the MRVA basal configuration. Stratal weakening from faulting and salt diapirism enhanced glacial incision and thereby produced abrupt aquifer thickening. We demarcate the top of graveliferous sands as the regional marker of the Pleistocene-Holocene transition. The MRVA hydrostratigraphy reveals hydrologic function and geologic controls on groundwater storage and quality, advancing the assessment of aquifer sustainability under a changing climate, with implications for alluvial aquifers globally.

Arkansas, Illinois, Kentucky, Louisiana, Mississip↗

USGS2005

Multiple sublethal chemicals negatively affect tadpoles of the green frog, Rana clamitans

Many habitats may be exposed to multiple chemical contaminants, particularly in agricultural areas where fertilizer and pesticide use are common; however, the singular and interactive effects of contaminants are not well understood. The objective of our study was to examine how realistic, sublethal environmental levels of ammonium nitrate fertilizer (0, 10, 20 mg/L and ammonium chloride control) and the common insecticide carbaryl (0 or 2.5 mg/L) individually and interactively affect the development, size, and survival of green frog ( Rana clamitans ) tadpoles. We reared tadpoles for 95 d in outdoor 1,000-L polyethylene ponds. We found that the combination of carbaryl and nitrate had a negative effect on development and mass of tadpoles compared to the positive effect that either contaminant had alone. Presence of carbaryl was generally associated with short-term increases in algal resources, including ponds exposed to both carbaryl and nitrate. However, with exposure to nitrate and carbaryl, tadpole mass and development were not positively affected as with one chemical stressor alone. The combination of these sublethal contaminants may reduce the ability of amphibians to benefit from food-rich environments or have metabolic costs. Our study demonstrates the importance of considering multiple stressors when evaluating population-level responses.

Environmental Toxicology↗

USGS2011

Development of industrial minerals in Colorado

Technology and engineering have helped make mining safer and cleaner for both humans and the environment. Inevitably, mineral development entails costs as well as benefits. Developing a mine is an environmental, engineering, and planning challenge that must conform to many Federal, State, and local regulations. Community collaboration, creative design, and best management practices of sustainability and biodiversity can be positive indicators for the mining industry. A better understanding of aesthetics, culture, economics, geology, climate, vegetation and wildlife, topography, historical significance, and regional land planning is important in resolving land-use issues and managing mineral resources wisely. Ultimately, the consuming public makes choices about product use (including water, food, highways, housing, and thousands of other items) that influence operations of the mineral industry. Land planners, resource managers, earth scientists, designers, and public groups have a responsibility to consider sound scientific information, society's needs, and community appeals in making smart decisions concerning resource use and how complex landscapes should change. An effort to provide comprehensive geosciences data for land management agencies in central Colorado was undertaken in 2003 by scientists of the U.S. Geological Survey and the Colorado Geological Survey. This effort, the Central Colorado Assessment Project, addressed a variety of land-use issues: an understanding of the availability of industrial and metallic rocks and minerals, the geochemical and environmental effects of historic mining activity on surface water and groundwater, and the geologic controls on the availability and quality of groundwater. The USDA Forest Service and other land management agencies have the opportunity to contribute to the sustainable management of natural aggregate and other mineral resources through the identification and selective development of mineral resources and the reclamation of mines on lands that they administer. The information in this Circular will help them carry out that task.

Colorado↗

USGS2024

Increasing phosphorus loss despite widespread concentration decline in US rivers

The loss of phosphorous (P) from the land to aquatic systems has polluted waters and threatened food production worldwide. Systematic trend analysis of P, a nonrenewable resource, has been challenging, primarily due to sparse and inconsistent historical data. Here, we leveraged intensive hydrometeorological data and the recent renaissance of deep learning approaches to fill data gaps and reconstruct temporal trends. We trained a multitask long short-term memory model for total P (TP) using data from 430 rivers across the contiguous United States (CONUS). Trend analysis of reconstructed daily records (1980–2019) shows widespread decline in concentrations, with declining, increasing, and insignificantly changing trends in 60%, 28%, and 12% of the rivers, respectively. Concentrations in urban rivers have declined the most despite rising urban population in the past decades; concentrations in agricultural rivers however have mostly increased, suggesting not-as-effective controls of nonpoint sources in agriculture lands compared to point sources in cities. TP loss, calculated as fluxes by multiplying concentration and discharge, however exhibited an overall increasing rate of 6.5% per decade at the CONUS scale over the past 40 y, largely due to increasing river discharge. Results highlight the challenge of reducing TP loss that is complicated by changing river discharge in a warming climate.

conterminous United States↗