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At least 1,477 records · Page 82Linked to original sources
USGS2010

Surface-Water Quality Conditions and Long-Term Trends at Selected Sites within the Ambient Water-Quality Monitoring Network in Missouri, Water Years 1993-2008

The U.S. Geological Survey, in cooperation with the Missouri Department of Natural Resources, collects data pertaining to the surface-water resources of Missouri. These data are collected as part of the Missouri Ambient Water-Quality Monitoring Network and constitute a valuable source of reliable, impartial, and timely information for developing an improved understanding of water resources in the State. Six sites from the Ambient Water-Quality Monitoring Network, with data available from the 1993 through 2008 water years, were chosen to compare water-quality conditions and long-term trends of dissolved oxygen, selected physical properties, total suspended solids, dissolved nitrate plus nitrite as nitrogen, total phosphorous, fecal indicator bacteria, and selected trace elements. The six sites used in the study were classified in groups corresponding to the physiography, main land use, and drainage basin size, and represent most stream types in Missouri. Long-term trends in this study were analyzed using flow-adjusted and non-flow adjusted models. Highly censored datasets (greater than 5 percent but less than 50 percent censored values) were not flow-adjusted. Trends that were detected can possibly be related to changes in agriculture or urban development within the drainage basins. Trends in nutrients were the most prevalent. Upward flow-adjusted trends in dissolved nitrate plus nitrite (as nitrogen) concentrations were identified at the Elk River site, and in total phosphorus concentrations at the South Fabius and Grand River sites. A downward flow-adjusted trend was identified in total phosphorus concentrations from Wilson Creek, the only urban site in the study. The downward trend in phosphorus possibly was related to a phosphorus reduction system that began operation in 2001 at a wastewater treatment plant upstream from the sampling site. Total suspended solids concentrations indicated an upward non-flow adjusted trend at the two northern sites (South Fabius and Grand Rivers). The increase in total suspended solids concentrations could be because of soil erosion from land cultivated for row crops. Most trace element data examined in the study were highly censored and could not be used for flow-adjusted trend analyses. Water-quality conditions were assessed to explore relations between data from sites and to the State water-quality standards where applicable for selected constituents. Streamflow varied at each site because of drainage area, land use, and groundwater inputs. Dissolved oxygen and water temperature were similar at all sites except the urban site located on Wilson Creek. Specific conductance was similar between the most northern (South Fabius and Grand River sites) and the most southern sites (Current and Elk River sites). Total suspended solids concentrations were near the method reporting level at all sites, except the northern sites. Streams in northern Missouri are more turbid than streams in southern Missouri and are affected by large volumes of sediment deposition because of soil erosion from land cultivated for row crops. Geometric means of Escherichia coli were calculated from the recreational seasons within the study period. Only the Grand River site exceeded the whole-body-contact standard for frequently used waters. The South Fabius and Grand River sites and the Wilson Creek site had statistically larger densities of both fecal indicator bacteria types than the remaining sites.

Scientific Investigations Report↗
USGS1997

The frequency and intensity of Atlantic hurricanes and their influence on the structure of south Florida mangrove communities

Hurricanes are formidable forces that wreak havoc on society and nature alike. Mangrove ecosystems are especially vulnerable because they thrive in the intertidal zone of tropical regions where hurricanes originate and are most frequent. Because mangroves are found at the land-sea interface where hurricanes are often most intense, these coastal forests are subject to damage from both high wind and surge. Mangroves are also an important habitat for many colonial and migratory birds and other wildlife, along with being nursery grounds for our fisheries. The fate of mangrove habitat as influenced by hurricanes may be threatened in the future under a global warming environment that might yield more intense storms than have been previously observed. Simulation models of hurricane abiotics and mangrove community dynamics have been developed to evaluate the effects of hurricanes on mangrove habitat across the South Florida landscape. Model applications show that hurricane frequency and intensity have varied spatially across Florida’s lower peninsula over the last century of record. Hindcast simulations of actual hurricane tracks and conditions seem to account for the structural composition of modernday mangrove forests across South Florida. A recurrence interval of major storms every 30 years over the last century is the major factor controlling mangrove ecosystem dynamics in South Florida. Some climate change models predict an increase in hurricane intensity over the next century that may further alter the structure and composition of our mangrove ecosystems. Model results of climate change scenarios indicate that future mangrove forests are likely to be diminished in stature and perhaps include a higher proportion of red mangroves. This modeling approach offers the ability to assess decadal and longer time scale changes in hurricane behavior and its effects on community structure and distribution of important plant associations such as the fate of mangrove habitat.

Florida↗
USGS2011

Setting limits: Using air pollution thresholds to protect and restore U.S. ecosystems

More than four decades of research provide unequivocal evidence that sulfur, nitrogen, and mercury pollution have altered, and will continue to alter, our nation's lands and waters. The emission and deposition of air pollutants harm native plants and animals, degrade water quality, affect forest productivity, and are damaging to human health. Many air quality policies limit emissions at the source but these control measures do not always consider ecosystem impacts. Air pollution thresholds at which ecological effects are observed, such as critical loads, are effective tools for assessing the impacts of air pollution on essential ecosystem services and for informing public policy. U.S. ecosystems can be more effectively protected and restored by using a combination of emissions-based approaches and science-based thresholds of ecosystem damage. Based on the results of a comprehensive review of air pollution thresholds, we conclude: ??? Ecosystem services such as air and water purification, decomposition and detoxification of waste materials, climate regulation, regeneration of soil fertility, production and biodiversity maintenance, as well as crop, timber and fish supplies are impacted by deposition of nitrogen, sulfur, mercury and other pollutants. The consequences of these changes may be difficult or impossible to reverse as impacts cascade throughout affected ecosystems. ??? The effects of too much nitrogen are common across the U.S. and include altered plant and lichen communities, enhanced growth of invasive species, eutrophication and acidification of lands and waters, and habitat deterioration for native species, including endangered species. ??? Lake, stream and soil acidification is widespread across the eastern United States. Up to 65% of lakes within sensitive areas receive acid deposition that exceeds critical loads. ??? Mercury contamination adversely affects fish in many inland and coastal waters. Fish consumption advisories for mercury exist in all 50 states and on many tribal lands. High concentrations of mercury in wildlife are also widespread and have multiple adverse effects. ??? Air quality programs, such as those stemming from the 1990 Clean Air Act Amendments, have helped decrease air pollution even as population and energy demand have increased. Yet, they do not adequately protect ecosystems from long-term damage. Moreover they do not address ammonia emissions. ??? A stronger ecosystem basis for air pollutant policies could be established through adoption of science-based thresholds. Existing monitoring programs track vital information needed to measure the response to policies, and could be expanded to include appropriate chemical and biological indicators for terrestrial and aquatic ecosystems and establishment of a national ecosystem monitoring network for mercury. The development and use of air pollution thresholds for ecosystem protection and management is increasing in the United States, yet threshold approaches remain underutilized. Ecological thresholds for air pollution, such as critical loads for nitrogen and sulfur deposition, are not currently included in the formal regulatory process for emissions controls in the United States, although they are now considered in local management decisions by the National Park Service and U.S. Forest Service. Ecological thresholds offer a scientifically sound approach to protecting and restoring U.S. ecosystems and an important tool for natural resource management and policy. ?? The Ecological Society of America.

Issues in Ecology↗
USGS2026

Rising atmospheric CO2 reduces nitrogen availability in boreal forests

Anthropogenic nitrogen (N) pollution has been emphasized as a cause of eutrophication globally. However, several recent datasets have suggested widespread oligotrophication may be occurring in some ecosystems, which is suggested to be a response to rising atmospheric carbon dioxide (eCO 2 ). Plant δ 15 N chronologies have served as primary evidence for oligotrophication, however, there has been wide disagreement whether eCO 2 or temporal changes in N deposition explain these patterns. We constructed δ 15 N tree ring chronologies across Sweden’s 23.5 million hectare productive forest area from the 1950s to 2010s. The study area spans a 1500 km latitudinal distance where N deposition varies four-fold, but where eCO 2 is spatially uniform. Our data revealed negative δ 15 N chronologies throughout Sweden, including forests in the far north where atmospheric N deposition rates are very low. Linear mixed effects models showed that eCO 2 was by far the strongest predictor of δ 15 N values, whereas N deposition variables, temperature, and forest basal area had much lower explanatory power. Our results clarify debates on the interpretation of previous δ 15 N chronologies, and provide clear evidence that eCO 2 is causing oligotrophication in boreal forests, which has implications for predicting their future role as sinks in the global carbon cycle.

Nature↗
USGS2020

Application of decadal modeling approach to forecast barrier island evolution, Dauphin Island, Alabama

Forecasting barrier island evolution provides coastal managers and stakeholders the ability to assess the resiliency of these important coastal environments that are home to both established communities and existing natural habitats. This study uses an established coupled model framework to assess how Dauphin Island, Alabama, responds to various storm and sea-level change scenarios, along with a suite of restoration measures, over the course of a decade. The coupled model framework uses validated models for long-term alongshore sediment transport (Delft 3D), short-term storm induced impacts (XBeach), as well as dune building and recovery (empirical dune growth model). This model framework was simulated with the various storm and sea-level change scenarios on a non-restored Dauphin Island, then a subset of the storm and sea-level change scenarios were applied to a suite of seven different restoration measures to determine how they would influence the morphologic evolution over a decadal period. Topographic and bathymetric changes captured in post-simulation digital elevation models were then passed on to partners for various simulations to determine the effects on habitat evolution and water quality as it relates to oyster reef and submerged aquatic vegetation.

Alabama↗
USGS2012

Edaphic, salinity, and stand structural trends in chronosequences of native and non-native dominated riparian forests along the Colorado River, USA

Tamarix spp. are introduced shrubs that have become among the most abundant woody plants growing along western North American rivers. We sought to empirically test the long-held belief that Tamarix actively displaces native species through elevating soil salinity via salt exudation. We measured chemical and physical attributes of soils (e.g., salinity, major cations and anions, texture), litter cover and depth, and stand structure along chronosequences dominated by Tamarix and those dominated by native riparian species ( Populus or Salix ) along the upper and lower Colorado River in Colorado and Arizona/California, USA. We tested four hypotheses: (1) the rate of salt accumulation in soils is faster in Tamarix -dominated stands than stands dominated by native species, (2) the concentration of salts in the soil is higher in mature stands dominated by Tamarix compared to native stands, (3) soil salinity is a function of Tamarix abundance, and (4) available nutrients are more concentrated in native-dominated stands compared to Tamarix -dominated stands. We found that salt concentration increases at a faster rate in Tamarix -dominated stands along the relatively free-flowing upper Colorado but not along the heavily-regulated lower Colorado. Concentrations of ions that are known to be preferentially exuded by Tamarix (e.g., B, Na, and Cl) were higher in Tamarix stands than in native stands. Soil salt concentrations in older Tamarix stands along the upper Colorado were sufficiently high to inhibit germination, establishment, or growth of some native species. On the lower Colorado, salinity was very high in all stands and is likely due to factors associated with floodplain development and the hydrologic effects of river regulation, such as reduced overbank flooding, evaporation of shallow ground water, higher salt concentrations in surface and ground water due to agricultural practices, and higher salt concentrations in fine-textured sediments derived from naturally saline parent material.

Colorado River↗
USGS2007

Investigation of wind and water level for the Giacomini Wetland Restoration Project, Point Reyes National Seashore

Point Reyes National Seashore (PRNS), comprising unique elements of geological, biological, and historical interest, is located on the central California coast approximately 60 km northwest of San Francisco. The National Seashore contains nearly 130 km of exposed and protected shorelines, spectacular coastal cliffs and headlands, lagoons, open grasslands, bushy hillsides, and forested ridges. Approximately 30 km of the shoreline are coastal-dune habitat that supports 11 federally listed species, including the threatened western snowy plover and the endangered plants Tidestrom's lupine ( Lupinus tidestromii ) and beach layia ( Layia carnosa ). The San Andreas Fault, a right-lateral strike-slip fault, trends northwest along the northeastern side of the park. Tomales Bay, which is straight, long, narrow, and shallow, runs along the northeastern boundary of PRNS. The Bay, which fills the northwestern end of a rift valley at the intersection of the San Andreas Fault with the coastline, is approximately 20 km long, 2 km wide, and 6 m deep with mountainous terrain to the southwest and rolling hills to the northeast. Tomales Bay is one of the cleanest estuaries on the West Coast. In winter, approximately 17,000 to 20,000 shorebirds inhabit Tomales Bay and Bodega Bay, which lies directly to the north. At the head of Tomales Bay, the Giacomini Ranch comprises 563 acres of pastureland currently being used for grazing dairy cattle. After more than 50 years of operation as a dairy, the National Park Service acquired the Giacomini property with the intention to restore most of it and the nearby Olema Marsh to tidal wetland. Restoration will add approximately 4% to the existing coastal wetlands in California. The project will return the headwaters of Tomales Bay and two major stream intersections to an intertidal marsh environment, enhancing habitat for both wildlife and fish populations and contributing to the long-term health of Tomales Bay. Prior to the establishment of the ranch, the area was primarily salt marsh that formed as the delta of Lagunitas Creek expanded into Tomales Bay. In converting the salt marsh to dairy land, levees and tide gates were constructed to prevent tidal incursion and stream flooding. Those levees have significantly altered the patterns of estuarine circulation and sediment deposition. To restore natural hydrologic processes within the area and to promote the return of ecological functions and processes, the levees will have to be breached or removed. Developing a successful restoration strategy requires knowledge of elevations within the pastureland and the range of water depths that can be expected from tidal, river, and wind action. In support of the restoration program, the USGS provides technical assistance to PRNS in the form of a scientific study focusing on understanding the physical processes that could affect the Giacomini wetland restoration. The study will yield scientific products that NPS resource managers can use in designing and implementing the restoration project. Research elements include: - Develop a Geodetic Control Network (GCN) throughout PRNS that meets the standards specified National Geodetic Survey data base (the NGS "Bluebook"). The grid will allow this and future studies to be conducted to a precision commensurate with the expressed goals of PRNS. The survey will consist of three steps: (1) verify existing GPS control monuments in the area; (2) tie control monuments in the study areas to the GPS control monuments; and (3) establish NAVD88 elevations using a digital electronic level. - Conduct a detailed survey of the Giacomini site to produce an accurate topographic map of the property. The site survey can be coupled with on-site water-level measurements to produce an empirical flooding model. - Measure water level and wind regime at the Giacomini site. The water-level range is critical to determining the wetland types based on the elevation of the dairy land. Water level at Sacramento Landing, in central Tomales Bay, will also be measured for comparison. As of November 2005, we have created a GCN, produced a detailed topographic map of the Giacomini site, and collected approximately three years of water-level and wind data at the Giacomini site and over one year of usable water-level data at the Sacramento Landing pier.

California↗
USGS2009

Final Report for Emergency Stabilization and Rehabilitation Treatment Monitoring of the Keeney Pass, Cow Hollow, Double Mountain, and Farewell Bend Fires

A strategy for monitoring post-fire seedings in the sagebrush steppe of the Intermountain West was developed and used to monitor four example fires in the Vale, Oregon District of the Bureau of Land Management (BLM). We began to develop a potential approach by (1) reviewing previous vegetation monitoring manuals produced by the Federal government to determine what techniques and approaches had been approved for use, and (2) monitoring a set of example fire rehabilitation projects from 2006 through 2008. We reviewed seven vegetation monitoring manuals approved for use by the Federal government. From these seven manuals, we derived a set of design elements appropriate for monitoring post-fire rehabilitation and stabilization projects. These design elements consisted of objectives, stratification, control plots, random sampling, data quality, and statistical analysis. Additionally, we chose three quantitative vegetation field procedures that were objective and repeatable to be used in conjunction with these six design elements. During the spring and summer of 2006 to 2008, U.S. Geological Survey personnel monitored vegetation in seven post-fire seeding treatments in four burned areas in the Vale district of the BLM in eastern Oregon. Treatments monitored included a native and non-native seeding in each of the Farewell Bend, Double Mountain, and Keeney Pass fires, and a native seeding at the Cow Hollow fire. All fires occurred in 2005. There generally was a low level of plant establishment for all seedings by 2008. The quantitative objective established by the BLM was to achieve 5 seeded grass plants/m2 by the end of 3 years as a result of the seeding. There was an estimated 3.97 and 6.28 plants/m2 in 2006 and 1.06 and 0.85 plants/m2 seeded perennial grasses in 2008 from the Keeney Pass non-native and native seeding, respectively. The Cow Hollow seeding resulted in the lowest establishment of perennial seeded grasses of the four project areas with 0.69 plants/m2 in 2006 and 0.09 plants/m2 in 2008. Density of seeded perennial grasses at the Double Mountain non-native and native seeding were 2.72 and 3.86 plants/m2 in 2006 and 0.90 and 1.74 plants/m2 in 2008, respectively. The Farewell Bend non-native seeding resulted in 5.62 plants/m2 in 2006 and 0.42 plants/m2 in 2008 while the native seeding had 2.22 seeded grass plants/m2 in 2006 and 0.44 plants/m2 by 2008. The primary reason for low level of establishment on most treatments except the Cow Hollow seeding was most likely the unfavorable timing and amount of precipitation in 2007 and 2008. Measurements of density within the first 3 years provide the best estimate of initial seeding success. Increases in cover due to the seedings were not detectable in the first 3 years following seeding in this monitoring effort. Changes in cover resulting from the treatments may be detectable in cases where the seedings were very successful in the first 3 years following seeding, but in areas with lower annual average precipitation, may not occur consistently. As a result, cover of seeded species may not be a good indication of seeding success in the early years after treatment. However, cover is useful for monitoring initial patterns of abundance of naturally recovering vegetation, exotic annual grasses and forbs, and bare ground. Cover measurements at these four sites revealed patterns common to most of the treatment areas in cover of litter, bare ground, and exotic annuals in response to drill seeding and weather patterns. There was a rapid increase in litter at all treatments after the fire. Additionally, there was less litter in treatment plots than in the control plots in 2006 probably due to the mechanical action of the seed drill. There also was a corresponding decrease in bare ground from 2006 to 2008. Initially, higher bare ground cover at treatment plots appears to be due to the mechanical action of the seed drill. Cover of annual grasses, primarily Bromus tectorum,

Open-File Report↗
USGS2014

Groundwater discharge by evapotranspiration, Dixie Valley, west-central Nevada, March 2009-September 2011

With increasing population growth and land-use change, urban communities in the desert Southwest are progressively looking toward remote basins to supplement existing water supplies. Pending applications by Churchill County for groundwater appropriations from Dixie Valley, Nevada, a primarily undeveloped basin east of the Carson Desert, have prompted a reevaluation of the quantity of naturally discharging groundwater. The objective of this study was to develop a revised, independent estimate of groundwater discharge by evapotranspiration (ET g ) from Dixie Valley using a combination of eddy-covariance evapotranspiration (ET) measurements and multispectral satellite imagery. Mean annual ET g was estimated during water years 2010 and 2011 at four eddy-covariance sites. Two sites were in phreatophytic shrubland dominated by greasewood, and two sites were on a playa. Estimates of total ET and ET g were supported with vegetation cover mapping, soil physics considerations, water‑level measurements from wells, and isotopic water sourcing analyses to allow partitioning of ET g into evaporation and transpiration components. Site-based ET g estimates were scaled to the basin level by combining remotely sensed imagery with field reconnaissance. Enhanced vegetation index and brightness temperature data were compared with mapped vegetation cover to partition Dixie Valley into five discharging ET units and compute basin-scale ET g . Evapotranspiration units were defined within a delineated groundwater discharge area and were partitioned as (1) playa lake, (2) playa, (3) sparse shrubland, (4) moderate-to-dense shrubland, and (5) grassland. Groundwater ET is influenced primarily by phreatophytic vegetative cover, salinity of soil and groundwater within the playa, depth to groundwater, solar radiation, and air temperature. The annual groundwater contribution to site‑scale ET ranged from 24 to 61 percent of total ET at vegetated sites and 4 to 15 percent of total ET at playa sites. Mean annual ET g from vegetated sites ranged from 53 millimeters (mm) (0.17 foot [ft], 7.3 percent vegetative cover) to 225 mm (0.74 ft, 24.8 percent vegetative cover). Cumulative liquid‑water fluxes in the unsaturated zone indicate that ET g at vegetated sites was influenced primarily by plant transpiration. Binary mixing analyses of oxygen-18 isotopes in groundwater and shallow soil water indicate that plants predominantly use groundwater throughout the year. Groundwater fractions in greasewood stem water varied seasonally and ranged from 0.63 to 1.0. Mean annual playa ET g ranged from about 11 mm (0.04 ft) at the inner playa site (near-surface volumetric water content of 37–53 percent) to about 20 mm (0.07 ft) at the outer playa site located within 2 kilometers of the playa edge (near-surface volumetric water content of 25–38 percent), but playa ET g estimates were within the probable error (plus or minus [±] 20–23 mm; 0.06–0.08 ft). Varying playa ET g was influenced predominantly by salinity rather than depth to groundwater. Osmotic resistance and physical impediments to ET (such as surface salt crusts and salt precipitate in the soil pore space) increased with increasing salinity toward the playa center, whereas vapor pressure decreased. Mean annual basin-scale ET g totaled about 28 million cubic meters (Mm 3 ) (23,000 acre-feet [acre-ft]), and represents the sum of ET g from all ET units. Annual groundwater ET from vegetated areas totaled about 26 Mm 3 (21,000 acre-ft), and was dominated by the moderate-to-dense shrubland ET unit (54 percent), followed by sparse shrubland (37 percent) and grassland (9 percent) ET units. Senesced grasses observed in the northern most areas of the moderate-to-dense ET unit likely confounded the vegetation index and led to an overestimate of ET g for this ET unit. Therefore, mean annual ET g for moderate-to-dense shrubland presented here is likely an upper bound. Annual groundwater ET from the playa ET unit was 2.2 Mm 3 (1,800 acre-ft), whereas groundwater ET from the playa lake ET unit was 0–0.1 Mm 3 (0–100 acre-ft). Oxygen-18 and deuterium data indicate discharge from the playa center predominantly represents removal of local precipitation-derived recharge. The playa lake estimate, therefore, is considered an upper bound. Mean annual ET g estimates for Dixie Valley are assumed to represent the pre‑development, long-term ET g rates within the study area.

Nevada↗
USGS1998

Surface-water quality at fixed sites in the Western Lake Michigan Drainages, Wisconsin and Michigan, and the effects of natural and human factors, 1993-95

Streamwater samples were collected from April 1993 through July 1995 at 11 fixed sites in the Western Lake Michigan Drainages Study Unit of the U.S. Geological Survey's National Water-Quality Assessment Program. Water samples were collected monthly at all Fixed Sites, and an additional two to four samples were collected each year during periods of high flow. Streamflow was monitored continuously at the Fixed Sites for the duration of the study period. This report describes field techniques used to collect the water samples, and the analytical methods used for laboratory analyses, statistical analyses of the data, and an attempt to determine the effect of natural and anthropogenic factors on concentrations of nutrients and selected major ions and suspended solids. Locations of eight of the Fixed Sites were selected to represent areas with unique combinations of land use/land cover, surficial deposits, and bedrock geology and are referred to as 'indicator sites.' The remaining three sites were located near the mouths of major rivers and are referred to as 'integrator sites.' The integrator sites represent a large part of the total flow from the Study Unit to Green Bay and western Lake Michigan, and drain various combinations of land use, bedrock, and surficial deposits. These data indicate that land use and surficial deposits may be the primary factors affecting nitrate and total phosphorus concentrations in this Study Unit. Median concentrations of nitrate at the forested sites were less than the National Median Concentration (NMC), and those at urban fixed sites were similar to the NMC. Median nitrate concentrations at the Tomorrow River, North Branch Milwaukee River, and Duck Creek agricultural indicator sites were twice the NMC, but median concentrations at the remaining agricultural indicator sites were similar to the NMC. Nitrate concentrations at one agricultural indicator site exceeded the U. S. Environmental Protection Agency (USEPA) maximum contaminant level in three run-off samples in the growing seasons of 1994 and 1995. Median concentrations of total phosphorus at the forested indicator sites were below the NMC. Tomorrow River was the only agricultural indicator site where the median total-phosphorus concentration was less than the NMC; median concentrations at the remaining agricultural Fixed Sites were similar to the NMC and exceeded 0.1 mg/L, the USEPA suggested total-phosphorus concentration in flowing water. The USEPA recommends that total-phosphorus concentration not exceed this limit to discourage excessive aquatic plant growth in flowing waters. Median total-phosphorus concentration at the urban indicator site was less than the urban NMC. Median concentrations for both nitrate and total phosphorus at the mouth of the Fox River and the Milwaukee River integrator sites were similar to the NMC for the dominant land use, agriculture, within their basins, and were lower than that at the Menominee River integrator site with a dominant forest land use. During this study, potassium concentrations were generally highest in areas of clay-dominated surficial deposits, silica was generally highest in areas of sandy surficial deposits, iron generally highest in areas of igneous/metamorphic bedrock, and calcium generally highest in areas of carbonate bedrock. The highest median fluoride concentration occurred at an urban site that receives treated water.

Michigan, Wisconsin↗
USGS2007

USGS Tampa Bay Pilot Study

Many of the nation's estuaries have been environmentally stressed since the turn of the 20th century and will continue to be impacted in the future. Tampa Bay, one the Gulf of Mexico's largest estuaries, exemplifies the threats that our estuaries face (EPA Report 2001, Tampa Bay Estuary Program-Comprehensive Conservation and Management Plan (TBEP-CCMP)). More than 2 million people live in the Tampa Bay watershed, and the population constitutes to grow. Demand for freshwater resources, conversion of undeveloped areas to resident and industrial uses, increases in storm-water runoff, and increased air pollution from urban and industrial sources are some of the known human activities that impact Tampa Bay. Beginning on 2001, additional anthropogenic modifications began in Tampa Bat including construction of an underwater gas pipeline and a desalinization plant, expansion of existing ports, and increased freshwater withdrawal from three major tributaries to the bay. In January of 2001, the Tampa Bay Estuary Program (TBEP) and its partners identifies a critical need for participation from the U.S. Geological Survey (USGS) in providing multidisciplinary expertise and a regional-scale, integrated science approach to address complex scientific research issue and critical scientific information gaps that are necessary for continued restoration and preservation of Tampa Bay. Tampa Bay stakeholders identified several critical science gaps for which USGS expertise was needed (Yates et al. 2001). These critical science gaps fall under four topical categories (or system components): 1) water and sediment quality, 2) hydrodynamics, 3) geology and geomorphology, and 4) ecosystem structure and function. Scientists and resource managers participating in Tampa Bay studies recognize that it is no longer sufficient to simply examine each of these estuarine system components individually, Rather, the interrelation among system components must be understood to develop conceptual and predictive modeling tools for effective ecosystem adaptive management. As a multidisciplinary organization, the USGS possesses the capability of developing and coordinating an integrated science strategy for estuarine research founded on partnerships and collaborative efforts, multidisciplinary teams of scientists, and integrated field work, data analysis and interpretation, and product development. The primary role of the USGS in Tamps Bay research was defined with our partners based upon this capability to address estuarine issues using an integrated science approach with a regional perspective and within a national context to complement the numerous ongoing scien efforts by state and local agencies that address local issues within Tamp Bay. Six primary components of the USGS Tamp Bay Study address critical gaps within each of the the four estuarine system components and focus on: 1.) Examining how natural and man-made physical changes affect ecosystem health through mapping and modeling. 2.) Identifying sources and quality of groundwater, surface water, and sediment, 3.) Identifying sources and quality of groundwater, surface water, and sediment, 4.) Assessing the natural and man-made changes affecting wetland health and restoration, 5.) Identifying and measuring the impact of urbanization on seafloor habitats, Providing a web-based digital information management system of information for scientists and the public, including a system that supports the work of those officials who must make decisions that affect the state of the bay. The Tampa Bay Study is in its sixth year and will continue through September 2007. This paper presents a non-inclusive summary of key findings associated with the six primary project components listed above. Component 4 (above) is described in detail in the following chapter 13. More information on the Tampa Bay Study is available from our on-line digital information system for the Tampa Bay Study at http://gulfsci.usgs.gov.

Florida↗
USGS2015

The vulnerability of Indo-Pacific mangrove forests to sea-level rise

Sea-level rise can threaten the long-term sustainability of coastal communities and valuable ecosystems such as coral reefs, salt marshes and mangroves. Mangrove forests have the capacity to keep pace with sea-level rise and to avoid inundation through vertical accretion of sediments, which allows them to maintain wetland soil elevations suitable for plant growth. The Indo-Pacific region holds most of the world’s mangrove forests, but sediment delivery in this region is declining, owing to anthropogenic activities such as damming of rivers. This decline is of particular concern because the Indo-Pacific region is expected to have variable, but high, rates of future sea-level rise. Here we analyse recent trends in mangrove surface elevation changes across the Indo-Pacific region using data from a network of surface elevation table instruments. We find that sediment availability can enable mangrove forests to maintain rates of soil-surface elevation gain that match or exceed that of sea-level rise, but for 69 per cent of our study sites the current rate of sea-level rise exceeded the soil surface elevation gain. We also present a model based on our field data, which suggests that mangrove forests at sites with low tidal range and low sediment supply could be submerged as early as 2070.

Indo-Pacific region↗
USGS1890

Volume XIII: The tertiary insects of North America

That creatures so minute and fragile as insects, creatures which can so feebly withstand the changing seasons as to live, so to speak, but a moment, are to be found fossil, engraved, as it were, upon the rocks or embedded in their hard mass, will never cease to be a surprise to those unfamiliar with the fact. "So fragile," says Quinet, "so easy to crush, you would readily believe the insect one of the latest beings produced by nature, one of those which has least resisted the action of time; that its type, its genera, its forms, must have been ground to powder a thousand times, annihilated by the revolutions of the globe, and perpetually thrown into the crucible. For where is its defense? Of what value its antennae, its shield, its wings of gauze, against the commotions and the tempests which change the surface of the earth? When the mountains themselves are overthrown and the seas uplifted, when the giants of structure, the mighty quadrupeds, change form and habit under the pressure of circumstances, will the insect withstand them? Is it it which will display most character in nature? Yes! The universe flings itself against a gnat. Where will it find refuge? In its very diminutiveness, its nothingness." The pages and plates of the present volume bear testimony to the fact that our tertiary strata have preserved remnants of an ancient host, so varied in structure, so closely also resembling their brethren of to-day, that nearly or quite every prevalent family-group in the entire range of the insect-world has already been demonstrated to have then existed. While often fragmentary and crushed, sometimes beyond recognition, a not insignificant number are sufficiently preserved for us to repopulate the past; sometimes, too, are they preserved in such a wonderful manner that in tiny creatures with a spread of wings scarcely more than a couple of millimeters one may count under the microscope the hairs fringing the wings. In attempting thus to restore the past world of our insects, two or three general features have been forced upon my attention, which may well be mentioned here. One of them is the rernarkable fact that in hardly a single instance has the same species been found at two distinct localities. These localities, it is true, are in some instances separated by hundreds or even thousands of miles, and analogy with the present distribution of insects would lead us to expect more or less profound changes in passing from one to another. But at other times the distance is not great, or at any rate not great enough to make this a satisfactory reason. It is more probable that the beds in which they occur are not altogether synchronous; and we are led to believe that in the separation of horizons insects will give more precise and definite distinctions than may be gained by the study of the plant remains of the same beds. The data at our disposal are not yet sufficiently varied to enable us to speak with any confidence, but when the other groups of Florissant insects, not considered in the present volume, are worked out, and the new material that is at hand from the other principal localities have been fairly studied, it may be found that we are armed with a new weapon of attack in solving the immediate succession of the Tertiary series of the West in their finer subdivisions. Another point to which attention may be drawn is the very considerable number and quite extraordinary proportion of species which so far are represented by a single specimen. Leaving out of consideration certain marvelously prevalent forms in the beds of Florissant, such as certain Formicidae, Alydina, etc., one working these beds, from which many thousands of insects have already been taken, may confidently expect that every third or fourth specimen will prove something new. A quite similar statement can be made of all, or all but one, of the other localities where insects have been found in our Tertiary deposits: it surely indicates that with all the rich results of the explorations so far undertaken we are only upon the threshold of our possible knowledge. We find a richness of fauna far exceeding anything before supposed possible. The interest of the Tertiary fauna is further enhanced by the discovery that no inconsiderable proportion of the species in this fauna must be referred to genera not now extant. Granted that our knowledge of the subtropical forms of this continent (with which as a whole at least our Florissant fauna seems to be akin) is much too meager to be of great service; granted also that in many cases we are forced to establish new genera upon what would be regarded among recent animals as too slender grounds : it is nevertheless true that an unexpectedly large number of forms can not be forced into modern genera already established; in many cases, throughout whole groups, kindred differences from modern types are found which indicate considerable changes of structure in the intervening epochs along parallel lines. In illustration of this we would call special attention to the differences observed in the genera of plant-lice, and, in several places among other Hemiptera as well as among the Coleoptera, to the decided differences in the relative length of various members of the body. My own belief, which springs from the comparisons instituted in the study of this fauna, is that a much larger proportion of genera should really have been founded, and that, for every type which may turn up in Central American explorations of the near future identical with those now established upon the fossils alone, it will be necessary to separate from the familiar surroundings in which I have placed it some other of the insects from the same beds. It should be stated that the larger part of the plates in this volume were engraved before the insects were studied, except in a cursory manner to separate the species; the insects are therefore not always properly grouped, and the legends upon the plates are in part inaccurate. In the enumeration of the specimens at the end of the specific descriptions the numbers of the obverse and reverse of the same specimen are always connected by "and" without any intervening comma, and this typographical method is employed only for expressing this relation. In the study of these extinct insects much assistance has been received from friends, to whom my cordial thanks are due; for valuable suggestions from the late Dr. J. L. LeConte, from Baron R. von Osten Sacken, Edward Burgess, Esq., and Drs. G. H. Horn and H. A. Hagen; for the open collections of the late G. D. Smith, Esq., and of Messrs. E. P. Austin and Samuel Henshaw; and for important aid in obtaining typical series of modern insects in various groups by Messrs. E. P. Austin, P. R. Uhler, E. P. Van Duzee, Edward Burgess, Dr. A. Forel, and most especially Mr. Samuel Henshaw.

British Columbia, Colorado, Ontario, Utah, Wyoming↗
USGS1998

Water-quality assessment of part of the upper Mississippi River basin, Minnesota and Wisconsin— Ground-water quality in an urban part of the Twin Cities Metropolitan area, Minnesota, 1996

In the spring of 1996, the Upper Mississippi River Basin Study Unit of the National Water-Quality Assessment Program drilled 30 shallow monitoring wells in a study area characterized by urban residential and commercial land uses. The monitoring wells were installed in sandy river-terrace deposits adjacent to the Mississippi River in Anoka and Hennepin Counties, Minnesota, in areas where urban development primarily occurred during the past 30 years. Analyses of sediments collected during well drilling indicated that at most well sites the aquifer materials had relatively high hydraulic conductivities (ranging from 0.01 to 238 feet per day), and relatively low organic carbon contents (0.10 to 41 grams per kilogram), indicating a high susceptibility to leaching of fertilizers and organic substances used on the land surface. Sediment pH values, which can affect leaching of pesticides, were generally alkaline, ranging from 5.1 to 9.6. Ground-water levels ranged from 2.39 to 23.14 feet below land surface, and indicated that shallow ground water flows primarily toward the Mississippi River. Dissolved-oxygen concentrations in water samples from the wells were generally less than 3 milligrams per liter (mg/L) and specific conductances were generally greater than 600 microsiemens per centimeter. Calcium, magnesium, sodium, bicarbonate, chloride, and sulfate were the primary dissolved constituents in the water samples. Sodium and chloride concentrations were generally greater than commonly reported in the region, probably due to leaching of sodium chloride applied to roads during the winter. Most tracemetal concentrations in ground-water samples were less than 10 micrograms per liter (μg/L), but concentrations of iron and manganese commonly exceeded Secondary Maximum Contaminant Levels set by the U.S. Environmental Protection Agency of 300 and 50 μg/L, respectively. Mineral saturation indices indicated that calcite, dolomite, and gypsum were slightly undersaturated in most water samples, and that quartz, and many oxides and hydroxides of iron and manganese were oversaturated in all of the water samples. Concentrations of nitrate nitrogen, the primary nutrient of concern in ground water, ranged from less than 0.05 to 16 mg/L, with a median concentration of 1.4 mg/L. Dissolved phosphorus concentrations ranged from less than 0.01 to 1.5 mg/L in the water samples, with a median concentration of 0.02 mg/L. Water from one well was oversaturated with respect to hydroxyapatite, a phosphatic mineral used as a fertilizer. Pesticide compounds were detected in water samples from 16 wells, but concentrations of those compounds were less than 1.0 μg/L. Prometon, an herbicide commonly used for right-of-way weed control, was detected in water samples from 10 of the wells. Atrazine, and its metabolite deethylatrazine, were detectable in water samples from 6 and 8 wells, respectively. Atrazine is commonly applied to land planted with corn and is detectable in rainfall and air samples in concentrations of less than 1 ng/L in the urban land use study area. Other detected pesticide compounds, which are used in agriculture, right-of-way weed control, or lawn care included: tebuthiuron, EPTC, p , p '-DDE, metolachlor, simazine, bentazon, and bromacil. Volatile organic compounds were detected in water samples from 26 wells, but the concentrations of most of those compounds were less than 1 μg/L. Carbon disulfide, which may be produced by bacteria in soils, was the most commonly detected volatile organic compound in water samples from the wells. Other detected volatile organic compounds included: methyl chloride, acetone, dichlorofluoromethane, tetrahydrofuran, trichlorofluoromethane, methyl iodide, 1,1-dichloroethane, chloroform, toluene, trichloroethane, trichloroethene, cis -1,2-dichloroethene, methylene chloride, bromodichloromethane, benzene, methylisobutylketone, ethyl ether, and tetrachloroethene. Tritium concentrations, analyzed in water samples from 15 of the 30 wells, indicated that shallow ground water has been recharged since the mid-1950's, and that shallow ground water should be affected by urban development that has taken place over the past 40 years. Land uses in the urban land use study area affected the concentrations of some water-quality constituents. Concentrations of nitrate and chloride, and frequencies of detection of pesticides and of volatile organic compounds, were greater in water samples from the surficial sand and gravel aquifer underlying the urban land use study area than in water samples from similar aquifers from part of the Upper Mississippi River Basin National Water-Quality Assessment study unit. Land uses within 500-meter radii of each well were quantified by digitizing overlays of aerial photographs that were verified and updated in the field. Concentrations of magnesium and sulfate were greater in ground water beneath areas of denser residential development, which may be a natural artifact of better drainage and a deeper water table in those areas. Frequencies of detection of some pesticides and volatile organic compounds were greater in water from wells with greater proportions of industrial and transportation land uses. Ground water in areas with less dense residential development, mostly the more recently-developed areas, tended to have greater concentrations of agricultural herbicides and some nutrients probably a relict of previous agricultural land use.

Minnesota↗
USGS1996

Physical, chemical, and biological characteristics of the Charlotte Harbor basin and estuarine system in southwestern Florida: A summary of the 1982-89 U.S. Geological Survey Charlotte Harbor assessment and other studies

The Charlotte Harbor estuarine system, having a surface area of about 270 square miles, averages about 7 feet in depth and is connected to deep water of the Gulf of Mexico through several passes and inlets between barrier islands. Three major rivers flow into the estuary--the Peace, the Myakka, and the Caloosahatchee. Freshwater and tidal flushing transport nutrients and other constituents from the basin through the estuary into the gulf. Flushing characteristics were evaluated using a two-dimensional hydrodynamic model. The model indicated that the time required to flush injected dye (simulated) from some subareas of the harbor was longer for reduced freshwater inflow than for typical freshwater inflow. After 30 days of simulation of reduced freshwater inflow, 42 percent of the dye injected into the upper harbor remained in the upper harbor, compared to 28 percent for typical freshwater inflow. The Charlotte Harbor estuary is usually well mixed or partially mixed in the vertical, but vertical salinity stratification does occur, primarily during late summer when freshwater inflows are greatest. A box model was developed that incorporated vertically averaged salinities to account indirectly for three-dimensional transport processes associated with vertical stratification. The box model predicts that under high (7,592 cubic feet per second) and average (2,470 cubic feet per second) freshwater inflows from the Peace and Myakka Rivers, 50 percent of the original water (present at the start of the model run) would be flushed from the northern part of the estuarine system into the Gulf of Mexico in 10 days and 20 days, respectively. The distribution of plant nutrients in the Charlotte Harbor Estuary is affected by nutrient inputs, freshwater and tidal flushing, mixing, and recycling processes in the estuary. The distributions of total phosphorus and orthophosphate are affected mainly by river input and physical mixing. The distribution of ammonia nitrogen is variable and is related more to recycling within the estuary than to input from the rivers. Ammonia concentrations increase in deeper water, probably in response to vertical salinity stratification and low concentrations of dissolved oxygen that foster regeneration of ammonia from bottom sediments. The distribution of nitrite plus nitrate nitrogen is nonconservative--concentrations are high in the rivers and decrease more rapidly in the estuary than expected due to dilution with sea water, probably because of phytoplankton uptake. Phytoplankton productivity and biomass are usually greatest during late summer near the mouths of the tidal rivers when freshwater inflow and nutrient loading are greatest. The highly colored freshwater runoff reduces light penetration and phytoplankton productivity in regions of the estuary where salinity is less than about 10 parts per thousand, but the nutrient-rich, colored water is diluted by seawater at midsalinities (10-20 parts per thousand) so that availability of light increases and inorganic nitrogen concentrations are still high enough to stimulate productivity and growth of phytoplankton. In much of the estuary, salinity is greater than 20 parts per thousand, and availability of inorganic nitrogen, not light, limits productivity and growth. Although the Charlotte Harbor estuarine system is relatively undisturbed, much of its basin has been altered by human activities. Streamflow decreased substantially during 1931-84 in parts of the Peace River, probably because of ground-water withdrawals in the basin. Nutrient concentrations generally increased in the rivers during 1970-85, because of an increase in the flow of wastewater and agricultural runoff. The concentrations of phosphorus are naturally high in the Peace River because of extensive phosphate deposits in the basin. The phosphate deposits also are relatively rich in radionuclides of the uranium-238 series, including radium-226. In the upper basin, these deposits are exposed in the riverbed. Extensive phosphate mining and processing have exposed additional deposits to surface runoff. Periodic spills of phosphate sediments (slimes) have contributed additional phosphorus and radium-226 to the river and estuary. A single spill can contribute a phosphorus load equal to the annual loading in the Peace River at Arcadia. The projected increase in population in the basin by the year 2020 would generate an additional 60 million gallons per day of domestic wastewater over that generated during 1980, which would increase nitrogen loading in the basin by more than 3 tons per day. Intensified agricultural and industrial developments, particularly expanding citrus production and phosphate mining, could generate additional loads of nutrients and a variety of inorganic and organic contaminants. Increased inputs of nutrients, particularly nitrogen, could encourage growth and increase abundance of phytoplankton and benthic and epiphytic algae. If water were less colored as a result of reduced freshwater inflow, undesirable algal growth could be exacerbated because of increased availability of light. Increased abundance of phytoplankton and other algae could likely change dissolved-oxygen concentrations in the estuary, resulting in greater day-to-night fluctuations and the possible depletion of dissolved oxygen in deep water. At the present time, near-anaerobic conditions occur for days or weeks in the deep water (more than 9 feet) of the northern harbor during late summer. These conditions could become more persistent with time and over wider areas, if phytoplankton and other algae increase in abundance and in their contribution to benthic oxygen demand. An increased abundance of phytoplankton and other algae also would reduce light penetration and adversely affect seagrasses.

Florida↗
USGS2021

Satellite-derived barrier response and recovery following natural and anthropogenic perturbations, northern Chandeleur Islands, Louisiana

The magnitude and frequency of storm events, relative sea-level rise (RSLR), sediment supply, and anthropogenic alterations drive the morphologic evolution of barrier island systems, although the relative importance of any one driver will vary with the spatial and temporal scales considered. To explore the relative contributions of storms and human alterations to sediment supply on de-cadal changes in barrier landscapes, we applied Otsu’s thresholding method to multiple satel-lite-derived spectral indices for coastal land-cover classification and analyzed Landsat satellite imagery to quantify changes to the northern Chandeleur Islands barrier system since 1984. This high temporal-resolution dataset shows decadal-scale land-cover oscillations related to storm–recovery cycles, suggesting that shorter and (or) less resolved time series are biased toward storm impacts and may significantly overpredict land-loss rates and the timing of barrier mor-phologic state changes. We demonstrate that, historically, vegetation extent and persistence were the dominant controls on alongshore-variable landscape response and recovery following storms, and are even more important than human-mediated sediment input. As a result of exten-sive vegetation losses over the past few decades, however, the northern Chandeleur Islands are transitioning to a new morphologic state in which the landscape is dominated by intertidal envi-ronments, indicating reduced resilience to future storms and possibly rapid transitions in mor-phologic state with increasing rates of RSLR.

Louisiana↗
USGS2014

Herbivores and nutrients control grassland plant diversity via light limitation

Human alterations to nutrient cycles and herbivore communities are affecting global biodiversity dramatically. Ecological theory predicts these changes should be strongly counteractive: nutrient addition drives plant species loss through intensified competition for light, whereas herbivores prevent competitive exclusion by increasing ground-level light, particularly in productive systems. Here we use experimental data spanning a globally relevant range of conditions to test the hypothesis that herbaceous plant species losses caused by eutrophication may be offset by increased light availability due to herbivory. This experiment, replicated in 40 grasslands on 6 continents, demonstrates that nutrients and herbivores can serve as counteracting forces to control local plant diversity through light limitation, independent of site productivity, soil nitrogen, herbivore type and climate. Nutrient addition consistently reduced local diversity through light limitation, and herbivory rescued diversity at sites where it alleviated light limitation. Thus, species loss from anthropogenic eutrophication can be ameliorated in grasslands where herbivory increases ground-level light.

Nature↗
USGS2025

Fungal impacts on Earth’s ecosystems

Over the past billion years, the fungal kingdom has diversified to more than two million species, with over 95% still undescribed. Beyond the well-known macroscopic mushrooms and microscopic yeast, fungi are heterotrophs that feed on almost any organic carbon, recycling nutrients through the decay of dead plants and animals and sequestering carbon into Earth’s ecosystems. Human-directed applications of fungi extend from leavened bread, alcoholic beverages and biofuels to pharmaceuticals, including antibiotics and psychoactive compounds. Conversely, fungal infections pose risks to ecosystems ranging from crops to wildlife to humans; these risks are driven, in part, by human and animal movement, and might be accelerating with climate change. Genomic surveys are expanding our knowledge of the true biodiversity of the fungal kingdom, and genome-editing tools make it possible to imagine harnessing these organisms to fuel the bioeconomy. Here, we examine the fungal threats facing civilization and investigate opportunities to use fungi to combat these threats.

Nature↗