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At least 1,009 records · Page 56Linked to original sources
USGS2021

Stream classification and gravel-bar inventory for Buffalo National River and Ozark National Scenic Riverways

The data summarized in this report provide a baseline characterization of the physical attributes of the riverine ecosystems in two landscapes managed by the National Park Service—Ozark National Scenic Riverways, Missouri, and Buffalo National River, Arkansas—to inform understanding and management of aquatic habitat. The study utilized a basin-scale approach and consisted of two components: a basin-scale channel classification and a longitudinal inventory of gravel bars. We evaluated the Jacks Fork and Current River in Ozark National Scenic Riverways and the main stem Buffalo River in Buffalo National River. The primary objective of the study was to characterize geomorphic patterns that affect channel stability and rates of geomorphic change in both national park units. Findings may be used to inform understanding of the distribution and availability of aquatic habitat. For the basin-scale channel classification, we performed exploratory statistical analyses using nine geomorphic variables (channel width, standard deviation in channel width, valley width, distance to valley wall, confinement, bar area, bluff area, braid index, and sinuosity). Each metric was quantified along the length of the river system at 200-meter intervals. We then performed a cluster analysis for each river using a subset of variables, resulting in 2 to 5 distinct geomorphic classes depending on criteria used for determining number of clusters. Longitudinal patterns in clusters vary for each river system but reflect a combination of landscape factors including valley width, influence of tributaries, and lithology, which affect channel stability and aquatic habitat. We developed a longitudinal inventory of gravel bars by quantifying the area of gravel bars from a series of imagery in each park. In Ozark National Scenic Riverways we analyzed five time periods, with the earliest being 1992 and most recent being 2014. In Buffalo National River, we also analyzed five series of aerial imagery, ranging from 1982 to 2013. The analysis indicated a general decrease in gravel storage in upstream reaches of each river evaluated, accompanied by a general increase in storage farther downstream. Local patterns in gravel-bar area are associated with longitudinal patterns in geomorphic setting, such as valley geometry and channel width, that affect depositional patterns and sediment storage at the reach scale.

Arkansas, Missouri↗
USGS2003

Planning for population viability on Northern Great Plains national grasslands

Broad-scale information in concert with conservation of individual species must be used to develop conservation priorities and a more integrated ecosystem protection strategy. In 1999 the United States Forest Service initiated an approach for the 1.2× 10 6 ha of national grasslands in the Northern Great Plains to fulfill the requirement to maintain viable populations of all native and desirable introduced vertebrate and plant species. The challenge was threefold: 1) develop basic building blocks in the conservation planning approach, 2) apply the approach to national grasslands, and 3) overcome differences that may exist in agency-specific legal and policy requirements. Key assessment components in the approach included a bioregional assessment, coarse-filter analysis, and fine-filter analysis aimed at species considered at-risk. A science team of agency, conservation organization, and university personnel was established to develop the guidelines and standards and other formal procedures for implementation of conservation strategies. Conservation strategies included coarse-filter recommendations to restore the tallgrass, mixed, and shortgrass prairies to conditions that approximate historical ecological processes and landscape patterns, and fine-filter recommendations to address viability needs of individual and multiple species of native animals and plants. Results include a cost-effective approach to conservation planning and recommendations for addressing population viability and biodiversity concerns on national grasslands in the Northern Great Plains.

Wildlife Society Bulletin↗
USGS2024

Can the planetary health concept save freshwater biodiversity and ecosystems?

People clearly need and benefit from healthy freshwater ecosystems; Given the precarious state of these important systems and services, current efforts to address the freshwater biodiversity crisis remain insufficient. Planetary health is an emerging framework that aims to secure the state of natural systems within environmental limits that ensure humanity can flourish. The planetary health concept is tied to the planetary boundaries framework in which various ecological thresholds are identified with the goal of constraining human activity to within those boundaries (so-called safe operating spaces). Freshwater systems are influenced by some planetary-scale processes like the climate systems and phosphorus and nitrogen cycles. Nonetheless, safe boundaries to guide the conservation and management of freshwater ecosystems need to consider their uneven distribution around the globe, and their ecological and hydrologic limits, which are often site and context dependent. Efforts to down-scale planetary boundaries concepts to the management of freshwater recreational fisheries at the lake scale, suggest that there are opportunities for rethinking planetary health as a nested cross-scale approach from the planet to the watershed.

Lancet Planetary Health↗
USGS2002

Distribution of grizzly bears in the Greater Yellowstone Ecosystem, 1990-2000

The Yellowstone grizzly bear ( Ursus arctos horribilis ) has been expanding its range during the past 2 decades and now occupies historic habitats that had been vacant. A current understanding of the distribution of grizzly bears within the ecosystem is useful in the recovery process and to help guide the state and federal land management agencies and state wildlife agencies of Idaho, Wyoming, and Montana as they prepare management plans. We used kernel estimators to develop distribution maps of occupied habitats based on initial sightings of unduplicated females (n = 300) with cubs-of-the-year, information from radiomarked bears (n = 105), and locations of conflicts, confrontations, and mortalities (n = 1,235). Although each data set was constrained by potential sampling bias, together they provided insight into areas within the Greater Yellowstone Ecosystem (GYE) currently occupied by grizzly bears. The current distribution (1990-2000) extends beyond the recovery zone identified in the U.S. Fish and Wildlife Service (USFWS) Recovery Plan. Range expansion is particularly evident in the southern portion of the ecosystem in Wyoming. A comparison of our results from the 1990s to previously published distribution maps show an approximate increase in occupied habitat of 48% and 34% from the 1970s and 1980s, respectively. We discuss data biases and problems implicit to the analysis.

Wyoming↗
USGS2004

Belowground dynamics in mangrove ecosystems

Mangrove ecosystems are tropical/subtropical communities of primarily tree species that grow in the intertidal zone. These tidal communities are important coastal ecosystems that are valued for a variety of ecological and societal goods and services (fig. 1). Mangrove wetlands are important filters of materials moving between the land and sea, trapping sediment, nutrients, and pollutants in runoff from uplands and preventing their direct introduction into sensitive marine ecosystems such as seagrass beds and coral reefs. Mangroves serve as nursery grounds and refuge for a variety of organisms and are consequently vital to the biological productivity of coastal waters. Furthermore, because mangroves are highly resilient to disturbances such as hurricanes, they represent a self-sustaining, protective barrier for human populations living in the coastal zone. Mangrove ecosystems also contribute to shoreline stabilization through consolidation of unstable mineral sediments and peat formation. In order to help conserve mangrove ecoystems, scientists with the United States Geological Survey (USGS) at the National Wetlands Research Center are working to more fully understand the dynamics that impact these vital ecosystems.

Fact Sheet↗
USGS2014

Earth observation based assessment of the water production and water consumption of Nile Basin agro-ecosystems

The increasing competition for water resources requires a better understanding of flows, fluxes, stocks, and the services and benefits related to water consumption. This paper explains how public domain Earth Observation data based on Moderate Resolution Imaging Spectroradiometer (MODIS), Second Generation Meteosat (MSG), Tropical Rainfall Measurement Mission (TRMM) and various altimeter measurements can be used to estimate net water production (rainfall (P) > evapotranspiration (ET)) and net water consumption (ET > P) of Nile Basin agro-ecosystems. Rainfall data from TRMM and the Famine Early Warning System Network (FEWS-NET) RainFall Estimates (RFE) products were used in conjunction with actual evapotranspiration from the Operational Simplified Surface Energy Balance (SSEBop) and ETLook models. Water flows laterally between net water production and net water consumption areas as a result of runoff and withdrawals. This lateral flow between the 15 sub-basins of the Nile was estimated, and partitioned into stream flow and non-stream flow using the discharge data. A series of essential water metrics necessary for successful integrated water management are explained and computed. Net water withdrawal estimates (natural and humanly instigated) were assumed to be the difference between net rainfall (P net ) and actual evapotranspiration (ET) and some first estimates of withdrawals—without flow meters—are provided. Groundwater-dependent ecosystems withdraw large volumes of groundwater, which exceed water withdrawals for the irrigation sector. There is a strong need for the development of more open-access Earth Observation databases, especially for information related to actual ET. The fluxes, flows and storage changes presented form the basis for a global framework to describe monthly and annual water accounts in ungauged river basins.

Remote Sensing↗
USGS2017

The land-sea interface: A source of high-quality phytoplankton to support secondary production

Coastal-estuarine systems are among the most productive marine ecosystems and their special role in producing harvestable fish and shellfish has been attributed to high primary production fueled by nutrient runoff from land and efficient trophic transfer. Here we ask if phytoplankton species composition and their food quality based on the percentage of long-chain essential fatty acids (LCEFA) is another factor contributing to high secondary production in these ecosystems. We used long-term measurements of major phytoplankton taxonomic groups and estimated their content of LCEFA along the salinity gradient in coastal-estuarine ecosystems, with emphasis on Chesapeake Bay and the Baltic Sea, and an oceanic transect. Our data show that cyanobacteria with low nutritional quality often dominate at low-salinity regions, while intermediate to higher salinity regions produce diatoms and dinoflagellates that have a higher content of LCEFA and are thus a higher-quality food resource for consumers. Higher salinity regions have less pronounced seasonal changes in the percentage of phytoplankton LCEFA compared to low salinity regions, providing a stable supply of nutritious phytoplankton to consumers. The phytoplankton LCEFA content is similarly high in coastal upwelling systems and it decreases further offshore in oligotrophic oceanic regions dominated by picophytoplankton. Our results from a broad range of coastal-ecosystem types show that ecosystems at the land-sea interface provide a valuable service by producing phytoplankton enriched in the biochemicals essential for consumers. High primary production, coupled with high quality of that production, explain why the production of fish and shellfish is high where land and sea meet.

Limnology and Oceanography↗
USGS2018

Conservation and restoration of mangroves: Global status, perspectives, and prognosis

Mangrove forests provide critical services around the globe to both human populations and the ecosystems they occupy. However, losses of mangrove habitat of more than 50% have been recorded in some parts of the world, and these losses are largely attributable to human activities. The importance of mangroves and the threats to their persistence have long been recognized, leading to actions taken locally, by national governments, and through international agreements for their protection. In this review, we explore the status of mangrove forests as well as efforts to protect them. We examine threats to the persistence of mangroves, consequences, and potential solutions for effective conservation. We present case studies from disparate regions of the world, showing that the integration of human livelihood needs in a manner that balances conservation goals can present solutions that could lead to long-term sustainability of mangrove forests throughout the world.

Ocean and Coastal Management↗
USGS2018

Northern Great Plains

In the Northern Great Plains, the timing and quantity of both precipitation and runoff have important consequences for water supplies, agricultural activities, and energy production. Overall, climate projections suggest that the number of heavy precipitation events (events with greater than 1 inch per day of rainfall) is projected to increase. Moving forward, the magnitude of year-to-year variability overshadows the small projected average decrease in streamflow. Changes in extreme events are likely to overwhelm average changes in both the eastern and western regions of the Northern Great Plains. Major flooding across the basin in 2011 was followed by severe drought in 2012, representing new and unprecedented variability that is likely to become more common in a warmer world. The Northern Great Plains region plays a critical role in national food security. Among other anticipated changes, projected warmer and generally wetter conditions with elevated atmospheric carbon dioxide concentrations are expected to increase the abundance and competitive ability of weeds and invasive species, increase livestock production and efficiency of production, and result in longer growing seasons at mid- and high latitudes. Net primary productivity, including crop yields and forage production, is also likely to increase, although an increasing number of extreme temperature events during critical pollination and grain fill periods is likely to reduce crop yields. Ecosystems across the Northern Great Plains provide recreational opportunities and other valuable goods and services that are ingrained in the region’s cultures. Higher temperatures, reduced snow cover, and more variable precipitation will make it increasingly challenging to manage the region’s valuable wetlands, rivers, and snow-dependent ecosystems. In the mountains of western Wyoming and western Montana, the fraction of total water in precipitation that falls as snow is expected to decline by 25% to 40% by 2100 under a higher scenario (RCP8.5), which would negatively affect the region’s winter recreation industry. At lower-elevation areas of the Northern Great Plains, climate-induced land-use changes in agriculture can have cascading effects on closely entwined natural ecosystems, such as wetlands, and the diverse species and recreational opportunities they support. Energy resources in the Northern Great Plains include abundant crude oil, natural gas, coal, wind, and stored water, and to a lesser extent, corn-based ethanol, solar energy, and uranium. The infrastructure associated with the extraction, distribution, and energy produced from these resources is vulnerable to the impacts of climate change. Railroads and pipelines are vulnerable to damage or disruption from increasing heavy precipitation events and associated flooding and erosion. Declining water availability in the summer would likely increase costs for oil production operations, which require freshwater resources. These cost increases will either lead to lower production or be passed on to consumers. Finally, higher maximum temperatures, longer and more severe heat waves, and higher overnight lows are expected to increase electricity demand for cooling in the summer, further stressing the power grid. Indigenous peoples in the region are observing changes to climate, many of which are impacting livelihoods as well as traditional subsistence and wild foods, wildlife, plants and water for ceremonies, medicines, and health and well-being. Because some tribes and Indigenous peoples are among those in the region with the highest rates of poverty and unemployment, and because many are still directly reliant on natural resources, they are among the most at risk to climate change (e.g., Gamble et al. 2016, Cozzetto et al. 2013, Espey et al. 2014, Wong et al. 2014, Kornfeld 2016, Paul and Caplins 2016, Maynard 2014, USGCRP 2017)

Report↗
USGS2019

Monitoring plans for Louisiana’s system-wide assessment and monitoring program (SWAMP). Version IV

The System-Wide Assessment and Monitoring Program (SWAMP) has been envisioned as a long-term monitoring program to ensure a comprehensive network of coastal data collection activities is in place to support the development, implementation, and adaptive management of the coastal protection and restoration program within coastal Louisiana. The Coastwide Reference Monitoring System (CRMS) and Barrier Island Comprehensive Monitoring (BICM) programs have been implemented under SWAMP, while other aspects of system dynamics, including offshore and inland water-body boundary conditions, nontidal freshwater habitats, riverine conditions, risk status, and protection performance, are not presently the subject of CPRA-coordinated (Coastal Protection and Restoration Authority) monitoring. In order to implement these additional aspects of SWAMP, CPRA partnered with The Water Institute of the Gulf and others to develop 1) a programmatic monitoring plan for evaluating the effectiveness of the coastal protection and restoration program on a coastwide scale, and 2) basinwide monitoring plans that will incorporate the elements of the programmatic plan with specific data collection activities designed to capture effects within the basin. Monitoring plans were developed for Barataria Basin, Pontchartrain Region (includes Breton Sound, Pontchartrain and Mississippi River Delta Basins), and the western basins (Calcasieu-Sabine, Mermentau, Teche-Vermilion, Atchafalaya, and Terrebonne) for both the natural and human systems using a process to identify the monitoring variables, objectives, and sampling design. The monitoring variables and objectives identified fall under the general categories of weather and climate, biotic integrity, water quality, hydrology, physical terrain, population and demographics, housing and community characteristics, economy and employment, ecosystem dependency, residential properties protection, and critical infrastructure and essential services protection. A rigorous statistical analysis, examination of modeling needs, and thorough reviews of previous planning and monitoring efforts were conducted to develop the sampling designs for the natural and human system monitoring plans. The plan relies heavily on the use of existing data, thus, coordination with other agencies (e.g., LDEQ , LDWF) and CPRA’s existing monitoring programs (e.g., BICM, CRMS) is critical to the plan’s success. Implementation of the plans will require development of quality control and quality assurance protocols, specific standardized operating procedures for each of the data collection efforts, a data management plan, and a reporting framework to contribute to decision making and reducing uncertainty in management actions.

Louisiana↗
USGS2021

USGS Chesapeake Science Strategy 2021-2025

The Chesapeake Bay ecosystem is a national treasure that provides almost $100 billion annually of goods and services. The Chesapeake Bay Program (CBP), is one of the largest federal-state restoration partnerships in the United States and is underpinned by rigorous science. The U.S. Geological Survey (USGS) has a pivotal role as a science provider for assessing ecosystem condition and response in the Chesapeake watershed. Despite significant CBP accomplishments, the pressures of climate change and competing demands on land use and change require an acceleration of progress towards the 10 goals in the Chesapeake Bay Watershed Agreement. USGS Chesapeake studies are increasing efforts to provide integrated science and are engaging stakeholders to inform the multi-faceted restoration and conservation decisions to improve habitat for fish and waterfowl, and socio-economic benefits to the 18 million people living in the watershed.

Delaware, Maryland, New York, Pennsylvania, Virgin↗
USGS2010

U.S. Geological Survey (USGS) Western Region Kasatochi Volcano Coastal and Ocean Science

Alaska is noteworthy as a region of frequent seismic and volcanic activity. The region contains 52 historically active volcanoes, 14 of which have had at least one major eruptive event since 1990. Despite the high frequency of volcanic activity in Alaska, comprehensive studies of how ecosystems respond to volcanic eruptions are non-existent. On August 7, 2008, Kasatochi Volcano, in the central Aleutian Islands, erupted catastrophically, covering the island with ash and hot pyroclastic flow material. Kasatochi Island was an annual monitoring site of the U.S. Fish and Wildlife Service, Alaska Maritime National Wildlife Refuge (AMNWR); therefore, features of the terrestrial and nearshore ecosystems of the island were well known. In 2009, the U.S. Geological Survey (USGS), AMNWR, and University of Alaska Fairbanks began long-term studies to better understand the effects of the eruption and the role of volcanism in structuring ecosystems in the Aleutian Islands, a volcano-dominated region with high natural resource values.

Fact Sheet↗
USGS2006

Organochlorine compounds and current-use pesticides in snow and lake sediment in Rocky Mountain National Park, Colorado, and Glacier National Park, Montana, 2002-03

Organochlorine compounds and current-use pesticides were measured in snow and lake-sediment samples from Rocky Mountain National Park in Colorado and Glacier National Park in Montana to determine their occurrence and distribution in high-elevation aquatic ecosystems. The U.S. Geological Survey, in cooperation with the National Park Service, collected snow samples at eight sites in Rocky Mountain National Park and at eight sites in Glacier National Park during spring of 2002 and 2003 just prior to the start of snowmelt. Surface sediments were collected from 11 lakes in Rocky Mountain National Park and 10 lakes in Glacier National Park during summer months of 2002 and 2003. Samples were analyzed for organochlorine compounds by gas chromatography with electron-capture detection and current-use pesticides by gas chromatography with electron-impact mass spectrometry. A subset of samples was reanalyzed using a third instrumental technique (gas chromatography with electron-capture negative ion mass spectrometry) to verify detected concentrations in the initial analysis and to investigate the presence of additional compounds. For the snow samples, the pesticides most frequently detected were endosulfan, dacthal, and chlorothalonil, all of which are chlorinated pesticides that currently are registered for use in North America. Concentrations of these pesticides in snow were very low, ranging from 0.07 to 2.36 nanograms per liter. Of the historical-use pesticides, hexachlorobenzene, dieldrin, and trans -nonachlor were detected in snow but only in one sample each. Annual deposition rates of dacthal, endosulfan, and chlorothalonil were estimated at 0.7 to 3.0 micrograms per square meter. These estimates are likely biased low because they do not account for pesticide deposition during summer months. For the lake-sediment samples, DDE ( p,p’ -dichlorodiphenyldichoroethene) and DDD ( p,p’ -dichlorodiphenyldichoroethane) were the most frequently detected organochlorine compounds. DDE and DDD are degradation products of DDT ( p,p’ -dichlorodiphenyltrichloroethane), which is a well-documented, persistent organochlorine insecticide that has been banned from use in the United States since 1972. Detected concentrations were very low, ranging from 0.12 to 4.7 micrograms per kilogram, and probably pose little threat to aquatic organisms in park lakes. DDD and DDE concentrations in a sediment core from Mills Lake in Rocky Mountain National Park indicate that atmospheric deposition of DDT and possibly other banned organochlorine compounds to high-elevation parks has been in decline since the 1970s. Commonly detected current-use pesticides in lake sediments included dacthal and endosulfan sulfate, which ranged in concentrations from 0.11 to 0.26 micrograms per kilogram for dacthal and 0.12 to 1.2 micrograms per kilogram for endosulfan sulfate. Both compounds were found in nearly all the snow samples, confirming that some current-use pesticides entering high-elevation aquatic ecosystems through atmospheric deposition are accumulating in lake sediments and potentially in aquatic biota.

Colorado, Montana↗
USGS2020

Assessment of rangeland ecosystem conditions in Grand Canyon-Parashant National Monument, Arizona

Sustainability of dryland ecosystems depends on the functionality of soil-vegetation feedbacks that affect ecosystem processes, such as nutrient cycling, water capture and retention, soil erosion and deposition, and plant establishment and reproduction. Useful, common indicators can provide information on soil and site stability, hydrologic function, and biotic integrity. Evaluation of rangeland health thus relies on describing the condition and sustainability of these individual, measurable, and observable indicators that are linked to important ecosystem processes. This report focuses on the ~200,000 acres of the Grand Canyon-Parashant National Monument that is administered by the National Park Service (NPS)—one of the largest NPS units where livestock grazing is a permitted land-use activity. Many ecosystems in the monument are characterized by a low degree of resilience to improper grazing because of low and variable precipitation. The monument is marked by a high degree of environmental heterogeneity, including a large elevation gradient, widely differing precipitation patterns, a diversity of geologic substrates, and unique combinations of plant species. The objective of this report is to (1) increase our understanding of the underlying landscape, soil, and climate setting factors that affect Grand Canyon-Parashant National Monument dryland ecosystem structure and function (also referred to as land potential) and (2) characterize the condition of monument ecosystems in relation to management concepts, such as rangeland health. Data were analyzed by elevation zone using both univariate and multivariate approaches. Survey results document the high level of diversity within the study area, including 15 unique soil taxa and 271 species of plants. We collected three new plant species for Grand Canyon-Parashant National Monument and 17 new species for the NPS portion of the monument. Results also document a strong association between rangeland health indicators and elevation, topographic setting, and soils. Soil factors found to explain important variation across plots include the amount of exposed bedrock, soil rockiness, soil texture (and associated hydrologic properties), and soil depth. We also found that dominant species turnover across elevation may represent species’ differences in adaptation to climates, including Larrea tridentata , Coleogyne ramosissima , and Artemisia spp. Bromus rubens is the most common invasive species of concern recorded in this study, but other common invasive species are Bromus tectorum , Erodium cicutarium , and Schismus arabicus . Correlations between an index of cattle use and indicators of rangeland health suggest that areas with high cattle use have increased bare ground, decreased ground cover, increased frequency of Schismus arabicus , decreased cover of Coleogyne ramosissima and Ephedra spp., and increased cover of Gutierrezia spp. The few strong correlations observed between indicators of vascular plant community cover or abundance and indicators of cattle activity support rangeland assessment and monitoring strategies that do not rely solely on plant-based indicators are needed. This work supports management of dryland ecosystems, including Grand Canyon-Parashant National Monument, using concepts of land potential. We conclude the report with recommendations on improving existing land-potential-based classification systems, associated interpretations, and methods for moving forward with a Grand Canyon-Parashant National Monument rangeland monitoring program.

Arizona↗
USGS2016

Effects of dams and geomorphic context on riparian forests of the Elwha River, Washington

Understanding how dams affect the shifting habitat mosaic of river bottomlands is key for protecting the many ecological functions and related goods and services that riparian forests provide and for informing approaches to riparian ecosystem restoration. We examined the downstream effects of two large dams on patterns of forest composition, structure, and dynamics within different geomorphic contexts and compared them to upstream reference conditions along the Elwha River, Washington, USA. Patterns of riparian vegetation in river segments downstream of the dams were driven largely by channel and bottomland geomorphic responses to a dramatically reduced sediment supply. The river segment upstream of both dams was the most geomorphically dynamic, whereas the segment between the dams was the least dynamic due to substantial channel armoring, and the segment downstream of both dams was intermediate due to some local sediment supply. These geomorphic differences were linked to altered characteristics of the shifting habitat mosaic, including older forest age structure and fewer young Populus balsamifera subsp. trichocarpa stands in the relatively static segment between the dams compared to more extensive early-successional forests (dominated by Alnus rubra and Salix spp.) and pioneer seedling recruitment upstream of the dams. Species composition of later-successional forest communities varied among river segments as well, with greater Pseudotsuga menziesii and Tsuga heterophylla abundance upstream of both dams, Acer spp. abundance between the dams, and P. balsamifera subsp. trichocarpa and Thuja plicata abundance below both dams. Riparian forest responses to the recent removal of the two dams on the Elwha River will depend largely on channel and geomorphic adjustments to the release, transport, and deposition of the large volume of sediment formerly stored in the reservoirs, together with changes in large wood dynamics.

Washington↗
USGS2008

Anthropogenic influences on the input and biogeochemical cycling of nutrients and mercury in Great Salt Lake, Utah, USA

Despite the ecological and economic importance of Great Salt Lake (GSL), little is known about the input and biogeochemical cycling of nutrients and trace elements in the lake. In response to increasing public concern regarding anthropogenic inputs to the GSL ecosystem, the US Geological Survey (USGS) and US Fish and Wildlife Service (USFWS) initiated coordinated studies to quantify and evaluate the significance of nutrient and Hg inputs into GSL. A 6??? decrease in ??15N observed in brine shrimp (Artemia franciscana) samples collected from GSL during summer time periods is likely due to the consumption of cyanobacteria produced in freshwater bays entering the lake. Supporting data collected from the outflow of Farmington Bay indicates decreasing trends in ??15N in particulate organic matter (POM) during the mid-summer time period, reflective of increasing proportions of cyanobacteria in algae exported to GSL on a seasonal basis. The C:N molar ratio of POM in outflow from Farmington Bay decreases during the summer period, supportive of the increased activity of N fixation indicated by decreasing ??15N in brine shrimp and POM. Although N fixation is only taking place in the relatively freshwater inflows to GSL, data indicate that influx of fresh water influences large areas of the lake. Separation of GSL into two distinct hydrologic and geochemical systems from the construction of a railroad causeway in the late 1950s has created a persistent and widespread anoxic layer in the southern part of GSL. This anoxic layer, referred to as the deep brine layer (DBL), has high rates of SO42 - reduction, likely increasing the Hg methylation capacity. High concentrations of methyl mercury (CH3Hg) (median concentration = 24 ng/L) were observed in the DBL with a significant proportion (31-60%) of total Hg in the CH3Hg form. Hydroacoustic and sediment-trap evidence indicate that turbulence introduced by internal waves generated during sustained wind events can temporarily mix the elevated CH3Hg concentrations in the DBL with the more biologically active upper brine layer (UBL). Brine shrimp collected during the summer/fall time periods contained elevated Hg concentrations (median concentration = 0.34 mg/kg, dry weight (dw)) relative to samples collected during the spring (median concentration < 0.2 mg/kg, dw). Higher Hg in brine shrimp during the summer and fall may reflect the higher proportion of adult brine shrimp during this time period, resulting in an increased time for bioaccumulation of Hg. Eared grebes (Podiceps nigricollis) consume brine shrimp from GSL during the fall molting period. Median Hg concentrations in eared grebe livers increased by almost three times during the 3-5 month fall molting period. Selected duck species utilizing GSL have consistently exceeded the US Environmental Protection Agency (USEPA) screening level for Hg (0.3 mg/kg Hg wet weight), resulting in the issuance of warnings against unlimited human consumption of breast muscle tissue.

Applied Geochemistry↗
USGS2012

Biodiversity loss and its impact on humanity

The most unique feature of Earth is the existence of life, and the most extraordinary feature of life is its diversity. Approximately 9 million types of plants, animals, protists and fungi inhabit the Earth. So, too, do 7 billion people. Two decades ago, at the first Earth Summit, the vast majority of the world's nations declared that human actions were dismantling the Earth's ecosystems, eliminating genes, species and biological traits at an alarming rate. This observation led to the question of how such loss of biological diversity will alter the functioning of ecosystems and their ability to provide society with the goods and services needed to prosper.

Nature↗
USGS2014

The Caloosahatchee River Estuary: A monitoring partnership between Federal, State, and local governments, 2007-13

The tidal Caloosahatchee River and downstream estuaries have substantial environmental, recreational, and economic value for southwest Florida residents and visitors. Modifications to the Caloosahatchee River watershed have altered the predevelopment hydrology, thereby threatening the environmental health of estuaries in the area. Hydrologic monitoring of the freshwater contributions from tributaries to the tidal Caloosahatchee River and its estuaries is necessary to adequately describe the total freshwater inflow and constituent loads to the delicate estuarine system. From 2007 to 2013, the U.S. Geological Survey (USGS), in cooperation with the Florida Department of Environmental Protection (FDEP) and the South Florida Water Management District (SFWMD), operated a flow and salinity monitoring network at tributaries flowing into and at key locations within the tidal Caloosahatchee River. This network was designed to supplement existing long-term monitoring stations, such as W.P. Franklin Lock, also known as S–79, which are operated by the USGS in cooperation with the U.S. Army Corps of Engineers, Lee County, and the City of Cape Coral. Additionally, a monitoring station was operated on Sanibel Island from 2010 to 2013 as part of the USGS Greater Everglades Priority Ecosystem Science initiative and in partnership with U.S. Fish and Wildlife Service (J.N. Ding Darling National Wildlife Refuge). Moving boat water-quality surveys throughout the tidal Caloosahatchee River and downstream estuaries began in 2011 and are ongoing. Information generated by these monitoring networks has proved valuable to the FDEP for developing total maximum daily load criteria, and to the SFWMD for calibrating and verifying a hydrodynamic model. The information also supports the Caloosahatchee River Watershed Protection Plan.

Florida↗