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USGS2019

Global observational needs and resources for marine biodiversity

The diversity of life in the sea is critical to the health of ocean ecosystems that support living resources and therefore essential to the economic, nutritional, recreational, and health needs of billions of people. Yet there is evidence that the biodiversity of many marine habitats is being altered in response to a changing climate and human activity. Understanding this change, and forecasting where changes are likely to occur, requires monitoring of organism diversity, distribution, abundance, and health. It requires a minimum of measurements including productivity and ecosystem function, species composition, allelic diversity, and genetic expression. These observations need to be complemented with metrics of environmental change and socio-economic drivers. However, existing global ocean observing infrastructure and programs often do not explicitly consider observations of marine biodiversity and associated processes. Much effort has focused on physical, chemical and some biogeochemical measurements. Broad partnerships, shared approaches, and best practices are now being organized to implement an integrated observing system that serves information to resource managers and decision-makers, scientists and educators, from local to global scales. This integrated observing system of ocean life is now possible due to recent developments among satellite, airborne, and in situ sensors in conjunction with increases in information system capability and capacity, along with an improved understanding of marine processes represented in new physical, biogeochemical, and biological models.

Frontiers in Marine Science↗

USGS2026

The WOAH global wildlife health collaborating centre network (WOAH-WildNet): A coordinated and transformative approach to global wildlife health challenges

Wildlife health is integral to functioning, complex ecosystems [ 1 ], directly and indirectly influencing the health of people, animals, plants, and the environment [ 2 – 4 ]. Healthy wildlife populations are essential for ecosystem services and are at the heart of the One Health approach [ 3 , 4 ], which aims to sustainably balance and optimize the health of people, animals, and ecosystems through multisectoral and transdisciplinary collaboration [ 5 ]. Despite its importance, wildlife health initiatives often operate in silos, limiting capacity to address transboundary threats such as emerging diseases, pollution, and environmental changes. Anthropogenic changes, including habitat loss, degradation, fragmentation, and unsustainable harvesting, exacerbate wildlife health challenges [6–9]. These pressures disrupt species biology and alter host-pathogen dynamics [10–12], underscoring the importance of coordinated collective action in addressing harmful effects on the health of wild animals. While local conservation efforts are vital, long-term success in safeguarding biodiversity requires a unified, global network. For instance, without harmonized surveillance and response systems, individual institutions cannot effectively track pathogens across borders or share diagnostic capabilities. The World Organisation for Animal Health (WOAH) Collaborating Centre Network for Wildlife Health—WOAH-WildNet—was established to bridge these gaps. By fostering global collaboration, sharing resources, and enabling data exchange, WOAH-WildNet provides a transformative, systems-based approach to wildlife health, managing risks, and enhancing ecosystem resilience. Central to this mission is breaking down silos to promote intersectoral coordinated responses to complex wildlife health challenges.

PLOS Sustainability and Transformation↗

USGS2014

Optical sensors for water quality

Shifts in land use, population, and climate have altered hydrologic systems in the United States in ways that affect water quality and ecosystem function. Water diversions, detention in reservoirs, increased channelization, and changes in rainfall and snowmelt are major causes, but there are also more subtle causes such as changes in soil temperature, atmospheric deposition, and shifting vegetation patterns. The effects on water quality are complex and interconnected, and occur at timeframes of minutes (e.g., flash floods) to decades (e.g., evolving management practices). However, water-quality monitoring has historically focused on discrete samples collected weekly or monthly, and laboratory analyses that can take days or weeks to complete. Low-frequency data and delayed access hampers a timely response during events, limits the ability to identify specific causes or actions, and may result in poorly quantified effects on ecosystems and human health at local to regional scales. Recent advancements in commercially available in situ sensors, data platforms, and new techniques for data analysis provide an opportunity to monitor water quality in rivers, lakes, and estuaries on the time scales in which changes occur. For example, measurements that capture the variability in freshwater systems over time help to assess how shifts in seasonal runoff, changes in precipitation intensity, and increased frequencies of disturbances (such as fire and insect outbreaks) affect the storage, production, and transport of carbon and nitrogen in watersheds. Transmitting these data in real-time also provides information that can be used for early trend detection, help identify monitoring gaps, and provide sciencebased decision support across a range of issues related to water quality, freshwater ecosystems, and human health.

Lakeline↗

USGS2024

Simulating past and future fire impacts on Mediterranean ecosystems

Worldwide, large wildfires are becoming increasingly common, leading to economic damages and threatening ecosystems and human health. Under future climate change, more frequent fire disturbance may push ecosystems into non-forested alternative stable states. Fire-prone ecosystems such as those in the Mediterranean Basin are expected to be particularly vulnerable, but the position of tipping points is unclear. We compare long-term palaeoecological data from Sardinia with output from a process-based dynamic vegetation model to investigate the mechanisms controlling the complex interactions between fire, climate, and vegetation in the past and the future. Our results show that past vegetation changes from Erica -shrublands to mixed evergreen-broadleaved Quercus ilex -dominated forests were driven by a climate-induced fire regime shift. By simulating vegetation dynamics under varying fire regimes, we could reproduce Holocene vegetation trajectories and mechanistically identify tipping points. Without an immediate reduction of greenhouse gas emissions, we simulate future expansion of fire-prone Mediterranean maquis and increasing fire occurrence. Similarly, high anthropogenic ignition frequencies and plantations of non-native, highly flammable trees could induce a shift to fire-adapted Erica shrublands. However, our simulations indicate that if global warming can be kept below 2°C, Quercus ilex forests will be able to persist and effectively reduce fire occurrences and impacts, making them a valuable restoration target in Mediterranean ecosystems. Synthesis . By combining long-term records of ecosystem change with a dynamic vegetation model, we show that past climate-driven fire regime shifts were the main driver of vegetation change, creating alternative stable states that persisted over centuries. Projected future climate change exceeding Holocene variability leads to pronounced vegetation changes and increased fire risks in our simulations, requiring new fire management strategies to maintain current ecosystem services.

Journal of Ecology↗

USGS2023

Using cyanobacteria and other phytoplankton to assess trophic conditions: A qPCR-based, multi-year study in twelve large rivers across the United States

Phytoplankton is the essential primary producer in fresh surface water ecosystems. However, excessive phytoplankton growth due to eutrophication significantly threatens ecologic, economic, and public health. Therefore, phytoplankton identification and quantification are essential to understanding the productivity and health of freshwater ecosystems as well as the impacts of phytoplankton overgrowth (such as Cyanobacterial blooms) on public health. Microscopy is the gold standard for phytoplankton assessment but is time-consuming, has low throughput, and requires rich experience in phytoplankton morphology. Quantitative polymerase chain reaction (qPCR) is accurate and straightforward with high throughput. In addition, qPCR does not require expertise in phytoplankton morphology. Therefore, qPCR can be a useful alternative for molecular identification and enumeration of phytoplankton. Nonetheless, a comprehensive study is missing which evaluates and compares the feasibility of using qPCR and microscopy to assess phytoplankton in fresh water. This study 1) compared the performance of qPCR and microscopy in identifying and quantifying phytoplankton and 2) evaluated qPCR as a molecular tool to assess phytoplankton and indicate eutrophication. We assessed phytoplankton using both qPCR and microscopy in twelve large freshwater rivers across the United States from early summer to late fall in 2017, 2018, and 2019. qPCR- and microscope-based phytoplankton abundance had a significant positive linear correlation (adjusted R 2 = 0.836, p -value < 0.001). Phytoplankton abundance had limited temporal variation within each sampling season and over the three years studied. The sampling sites in the midcontinent rivers had higher phytoplankton abundance than those in the eastern and western rivers. For instance, the concentration (geometric mean) of Bacillariophyta, Cyanobacteria, Chlorophyta, and Dinoflagellates at the sampling sites in the midcontinent rivers was approximately three times that at the sampling sites in the western rivers and approximately 18 times that at the sampling sites in the eastern rivers. Welch's analysis of variance indicates that phytoplankton abundance at the sampling sites in the midcontinent rivers was significantly higher than that at the sampling sites in the eastern rivers ( p -value = 0.013) but was comparable to that at the sampling sites in the western rivers ( p -value = 0.095). The higher phytoplankton abundance at the sampling sites in the midcontinent rivers was presumably because these rivers were more eutrophic. Indeed, low phytoplankton abundance occurred in oligotrophic or low trophic sites, whereas eutrophic sites had greater phytoplankton abundance. This study demonstrates that qPCR-based phytoplankton abundance can be a useful numerical indicator of the trophic conditions and water quality in freshwater rivers.

Water Research↗

USGS2025

Interaction strength and harvest intensity mediate predator–prey dynamics on coral reefs

Understanding predator–prey relationships is fundamental to our knowledge of the stability and resilience of ecological systems. These dynamics are shaped by both ecological factors, like interaction strength, and anthropogenic factors, like harvest intensity, which can have large-scale implications for community structure. However, few studies have focused on the combined impact of these effects and their contribution to phenomena like prey release within two-species frameworks. In this study, we investigate the interactive impact of interaction strength and harvest pressure on two trophic levels in a predator–prey system using a mathematical modeling approach. Our results reveal that interaction strength plays a crucial role in shaping population dynamics, with high interaction strength leading to a predator-dominated system and low interaction strength enabling coexistence between species. The addition of predator harvest into the system reveals complex and counterintuitive behavior not seen in unharvested systems, likely due to the destabilizing impacts of harvest at some interaction strengths. Specifically, the inclusion of harvest on the predator can induce a range of behaviors, such as prey release and predator decline, that alter the equilibrium abundance of both predator and prey populations. Interestingly, predator–prey systems with intermediate to high interaction strengths achieve maximum total abundance with low harvest levels rather than in scenarios with no harvest pressure, as prey populations benefit greatly from reduced predation mortality associated with predator harvest. We gain insights into the complex interplay between predator–prey interactions and human activities in shaping community composition and abundances across trophic levels. This study provides potential mechanisms that may explain the observed variation in numerical prey release in trophically complex systems in which predators and prey are both extracted, like coral reef fisheries. Results highlight the need for resource management to consider the wide range of factors that shape ecosystem dynamics to develop effective strategies that safeguard the long-term health of complex ecosystems and the human communities that they support.

Ecosphere↗

USGS2022

Reimagine fire science for the anthropocene

Fire is an integral component of ecosystems globally and a tool that humans have harnessed for millennia. Altered fire regimes are a fundamental cause and consequence of global change, impacting people and the biophysical systems on which they depend. As part of the newly emerging Anthropocene, marked by human-caused climate change and radical changes to ecosystems, fire danger is increasing, and fires are having increasingly devastating impacts on human health, infrastructure, and ecosystem services. Increasing fire danger is a vexing problem that requires deep transdisciplinary, trans-sector, and inclusive partnerships to address. Here, we outline barriers and opportunities in the next generation of fire science and provide guidance for investment in future research. We synthesize insights needed to better address the long-standing challenges of innovation across disciplines to (i) promote coordinated research efforts; (ii) embrace different ways of knowing and knowledge generation; (iii) promote exploration of fundamental science; (iv) capitalize on the “firehose” of data for societal benefit; and (v) integrate human and natural systems into models across multiple scales. Fire science is thus at a critical transitional moment. We need to shift from observation and modeled representations of varying components of climate, people, vegetation, and fire to more integrative and predictive approaches that support pathways toward mitigating and adapting to our increasingly flammable world, including the utilization of fire for human safety and benefit. Only through overcoming institutional silos and accessing knowledge across diverse communities can we effectively undertake research that improves outcomes in our more fiery future.

PNAS Nexus↗

USGS2016

Anticipating environmental and environmental-health implications of extreme storms: ARkStorm scenario

The ARkStorm Scenario predicts that a prolonged winter storm event across California would cause extreme precipitation, flooding, winds, physical damages, and economic impacts. This study uses a literature review and geographic information system-based analysis of national and state databases to infer how and where ARkStorm could cause environmental damages, release contamination from diverse natural and anthropogenic sources, affect ecosystem and human health, and cause economic impacts from environmental-remediation, liability, and health-care costs. Examples of plausible ARkStorm environmental and health concerns include complex mixtures of contaminants such as petroleum, mercury, asbestos, persistent organic pollutants, molds, and pathogens; adverse physical and contamination impacts on riverine and coastal marine ecosystems; and increased incidences of mold-related health concerns, some vector-borne diseases, and valley fever. Coastal cities, the San Francisco Bay area, the Sacramento-San Joaquin River Delta, parts of the Central Valley, and some mountainous areas would likely be most affected. This type of screening analysis, coupled with follow-up local assessments, can help stakeholders in California and disaster-prone areas elsewhere better plan for, mitigate, and respond to future environmental disasters.

Natural Hazards Review↗

USGS2010

Climate change and wildlife health: direct and indirect effects

Climate change will have significant effects on the health of wildlife, domestic animals, and humans, according to scientists. The Intergovernmental Panel on Climate Change projects that unprecedented rates of climate change will result in increasing average global temperatures; rising sea levels; changing global precipitation patterns, including increasing amounts and variability; and increasing midcontinental summer drought (Intergovernmental Panel on Climate Change, 2007). Increasing temperatures, combined with changes in rainfall and humidity, may have significant impacts on wildlife, domestic animal, and human health and diseases. When combined with expanding human populations, these changes could increase demand on limited water resources, lead to more habitat destruction, and provide yet more opportunities for infectious diseases to cross from one species to another. Awareness has been growing in recent years about zoonotic diseases— that is, diseases that are transmissible between animals and humans, such as Lyme disease and West Nile virus. The rise of such diseases results from closer relationships among wildlife, domestic animals, and people, allowing more contact with diseased animals, organisms that carry and transmit a disease from one animal to another (vectors), and people. Disease vectors include insects, such as mosquitoes, and arachnids, such as ticks. Thus, it is impossible to separate the effects of global warming on wildlife from its effects on the health of domestic animals or people. Climate change, habitat destruction and urbanization, the introduction of exotic and invasive species, and pollution—all affect ecosystem and human health. Climate change can also be viewed within the context of other physical and climate cycles, such as the El Niño Southern Oscillation (El Niño), the North Atlantic Oscillation, and cycles in solar radiation that have profound effects on the Earth’s climate. The effects of climate change on wildlife disease are summarized in several areas of scientific study discussed briefly below: geographic range and distribution of wildlife diseases, plant and animal phenology (Walther and others, 2002), and patterns of wildlife disease, community and ecosystem composition, and habitat degradation.

Fact Sheet↗

USGS2024

7.10 - Beneficiaries, equity, and trade-offs in estuarine and coastal ecosystem services

Estuarine and coastal ecosystems support human populations in myriad ways. Traditionally, researchers have focused on the biophysical processes that underlie these benefits and their economic values. In the decade since the 1st Treatise, the literature on cultural ecosystem services, human health benefits, and the equitable distribution of societal benefits and burdens has grown tremendously. In this chapter we outline three dimensions of equity as they relate to estuarine and coastal ecosystems: procedural, recognitional, and distributional equity. We then apply the dimensions of equity to a suite of provisioning, regulating, and cultural ecosystem services. Finally, we explore trade-offs and beneficiaries of these ecosystem services using three case studies that consider equity in a variety of estuarine and coastal management decisions.

Book chapter↗

USGS2021

NASA's surface biology and geology designated observable: A perspective on surface imaging algorithms

The 2017–2027 National Academies' Decadal Survey, Thriving on Our Changing Planet , recommended Surface Biology and Geology (SBG) as a “Designated Targeted Observable” (DO). The SBG DO is based on the need for capabilities to acquire global, high spatial resolution, visible to shortwave infrared (VSWIR; 380–2500 nm; ~30 m pixel resolution) hyperspectral (imaging spectroscopy) and multispectral midwave and thermal infrared (MWIR: 3–5 μm; TIR: 8–12 μm; ~60 m pixel resolution) measurements with sub-monthly temporal revisits over terrestrial, freshwater, and coastal marine habitats. To address the various mission design needs, an SBG Algorithms Working Group of multidisciplinary researchers has been formed to review and evaluate the algorithms applicable to the SBG DO across a wide range of Earth science disciplines, including terrestrial and aquatic ecology, atmospheric science, geology, and hydrology. Here, we summarize current state-of-the-practice VSWIR and TIR algorithms that use airborne or orbital spectral imaging observations to address the SBG DO priorities identified by the Decadal Survey: (i) terrestrial vegetation physiology, functional traits, and health; (ii) inland and coastal aquatic ecosystems physiology, functional traits, and health; (iii) snow and ice accumulation, melting, and albedo; (iv) active surface composition (eruptions, landslides, evolving landscapes, hazard risks); (v) effects of changing land use on surface energy, water, momentum, and carbon fluxes; and (vi) managing agriculture, natural habitats, water use/quality, and urban development. We review existing algorithms in the following categories: snow/ice, aquatic environments, geology, and terrestrial vegetation, and summarize the community-state-of-practice in each category. This effort synthesizes the findings of more than 130 scientists.

Remote Sensing of Environment↗

USGS2008

Use of Numerical Models to Simulate Transport of Sewage-Derived Nitrate in a Coastal Aquifer, Central and Western Cape Cod, Massachusetts

The unconsolidated glacial sediments underlying Cape Cod, Massachusetts compose a regional aquifer system that is used both as a source of drinking water and as a disposal site for wastewater; in addition, the discharge of clean ground water from the aquifer system is needed for the maintenance of freshwater and marine ecosystems throughout the region. Because these uses of the aquifer conflict with one another in many areas of the Cape, local and regional planners have begun to develop sustainable wastewater plans that will facilitate the disposal of wastewater while protecting water supplies and improving the health of aquatic ecosystems. To assist local and regional planners in these efforts, the U.S. Geological Survey conducted a 2-year investigation to (1) assist local and regional planners in the evaluation of potential wastewater scenarios, (2) use results and interpretation from these analyses to develop hydrologic concepts transferable throughout the region, and (3) establish and test methods that would be of use in future evaluations. Wastewater-disposal scenarios need to be evaluated in the context of the regional ground-water-flow system. For a given rate of disposal, wastewater from sites at or near a regional ground-water divide is transported in a wider arc of flow directions, flows deeper in the system, and contaminates a larger part of the aquifer than does wastewater discharged from sites farther from the divide. Also, traveltimes of wastewater from sites near a ground-water divide to receptors are longer (as much as several hundred years) than traveltimes from sites farther from the divide. Thus, wastewater disposal at or near a divide will affect a larger part of the aquifer and likely contribute wastewater to more receptors than wastewater disposal farther from a divide; however, longer traveltimes could allow for more attenuation of wastewater-derived nitrate from those sites. Ground-water-flow models and particle tracking can be used to identify advective-transport patterns downgradient from wastewater-disposal sites and estimate traveltimes; however, these tools cannot predict the distribution of mass or concentrations of wastewater constituents, such as nitrate, in the aquifer. Flow-based particle-tracking analyses can be used to estimate mass-loading rates and time-varying concentrations at wells and ecological receptors by the accounting of mass-weighted particles discharging into the receptor of interest. This method requires no additional development beyond the flow model; however, post-modeling analyses are required. In addition, the method is based on the assumption that no mass is lost during transport, an assumption that likely is not valid in many systems. Solute-transport models simulate the subsurface transport of nitrate through the aquifer and predict the distribution of the mass of a solute in the aquifer at different transport times. This method does require additional model development beyond the flow model, but can predict timevarying concentrations at receptors. Estimates of mass-loading rates require minimal post-modeling analyses. Time-varying concentrations and mass-loading rates calculated for wells in eastern Barnstable by the two methods generally were in reasonable agreement. Inherent in the flow-based particle-tracking method is the assumption that mass is conserved along a given flow line and that there is no spreading of mass in the aquifer. Although the solute-transport models also incorporate a system-wide conservation of mass, these models allow for a spreading of mass in the aquifer, and mass is not conserved along a given flow line. As a result, estimates of concentrations and mass loading rates generally were higher in particle-tracking analyses than in solute-transport simulations. Results from the two types of simulations agreed best for wells that receive large amounts of wastewater with short traveltimes (less than 10 years) because insufficient transport

Scientific Investigations Report↗

USGS2018

Indicators of ecosystem structure and function for the Upper Mississippi River System

This report documents the development of quantitative measures (indicators) of ecosystem structure and function for use in a Habitat Needs Assessment (HNA) for the Upper Mississippi River System (UMRS). HNAs are led periodically by the U.S. Army Corps of Engineers’ Upper Mississippi River Restoration (UMRR) Program, which is the primary habitat restoration program on the UMRS. The UMRR Program helps determine how Federal, State and nongovernmental agencies can best address environmental issues on one of the world’s largest and most diverse river systems. Each indicator in this report represents at least one management objective developed for the river system. These objectives were developed in a previous planning effort using an ecosystem management conceptual framework (USACE, 2011). The objectives represent five essential ecosystem characteristics: hydraulics and hydrology, biogeochemistry, geomorphology, habitat, and biota. Subsequent to the 2011 planning effort, the UMRR increased its focus on improving the health and resilience of the UMRS. The indicators presented here are based on the five essential ecosystem characteristics and four aspects of ecosystems thought to support general ecosystem resilience (the ability of an ecosystem to adapt and respond to disturbances): (1) connectivity, (2) diversity and redundancy, (3) controlling variables, and (4) slow processes. Thus, we developed indicators that quantify both essential ecosystem characteristics and characteristics of a resilient river system. The indicators documented in this report focus on important aspects of river floodplain hydrogeomorphology, given the fundamental role hydrogeomorphology plays in determining habitat conditions and ecosystem health and resilience at broad geographic scales. The information contained within this report provides a broader scale (for example, system-wide) context for management decisions made at finer scales (for example, within river reaches or at project sites) and is designed for use in the formal system-wide Habitat Needs Assessment II (HNA–II) led by the UMRR Program.

Upper Mississippi River System↗

USGS1996

Influences of environmental settings on aquatic ecosystems in the Apalachicola-Chattahoochee-Flint River basin

The watershed boundary of the Apalachicola-Chattahoochee-Flint (ACF) River basin defines an aquatic ecosystem whose water quality is the result of complex interactions of natural and human influences on land and water resources. Topics relating to the basin's environmental setting-its physical, biological, and cultural characteristics-are summarized to provide an understanding of factors that influence water quality and the health of aquatic ecosystems. The ACF River basin lies partly in southwestern Georgia, southeastern Alabama, and northwestern Florida and covers 19,800 square miles in the Blue Ridge, the Piedmont, and the Coastal Plain Provinces. The basin includes the drainages of the Chattahoochee River and the Flint River, which meet to form the Apalachicola River. The Apalachicola River flows into the Gulf of Mexico at Apalachicola Bay. Basin hydrology and water quality are influenced by 16 mainstem reservoirs, 13 of which are on the Chattahoochee River. Ground water in the basin is contained in six aquifers-the surficial aquifer system, the Floridan aquifer system, the Claiborne aquifer, the Clayton aquifer, the Providence aquifer, and the crystalline-rock aquifer. Physiography, climate, and hydrology of the ACF River basin provide natural conditions that support a rich and abundant diversity of plants and animals. Although most of the ACF River basin has been altered by human activities, the basin's environment is noteworthy for its remaining biological diversity and the role it plays in sustaining biological productivity in Apalachicola Bay. The Bay produces 90 percent of Florida's and 13 percent of the Nation's oyster harvest; and functions as a nursery for penaeid shrimp, blue crabs, and a variety of fin fish. The diversity of the basin's aquatic fauna is noteworthy because the basin is home to (1) the largest number of fish species among Gulf Coast drainages east of the Mississippi River, (2) the largest assemblage of freshwater fish in Florida, (3) the largest number of mollusc species among western Florida drainages, and (4) the highest species density of amphibians and reptiles on the continent north of Mexico. Population of the ACF River basin in 1990 was estimated at 2.6 million. Nearly 90 percent of the total population lived in Georgia, and nearly 60 percent lived in the Metropolitan Atlanta area. The 1990 basin population is projected to increase by 15 percent to 3.0 million by the year 2000, and by 30 percent to 3.4 million by 2010. The largest increases in populations are projected for the Metropolitan Atlanta area. In 1972-76, approximately 59 percent of the basin was covered by forest, 29 percent was agricultural, 5 percent was wetland, 4 percent was urban, and 3 percent was water or barren land. Most of the original land cover of the basin has been transformed by human activity. Timber is the basin's largest cash crop and most forests consist of second-growth stands or large acreages of planted pine. The dominant agricultural land use in the Piedmont Province is pasture and confined feeding for dairy, livestock, and poultry production. Row-crop agriculture, orchards, and silviculture are most common in the Coastal Plain Province. The top five crops in order from most to least acres harvested in 1990 were peanuts, corn, soybeans, wheat, and cotton. The water in the basin is used for public and industrial supply, irrigation, power generation, navigation, and recreation. Although most public-supply withdrawals in the Blue Ridge and Piedmont Provinces are from surface-water sources, with the exception of counties near or immediately below the Fall Line, all publicly supplied water in the Coastal Plain is withdrawn from ground-water sources. Ground water supplied 18 percent of the basin's population served by public supply. Total water withdrawn in the ACF River basin in 1990 was 2,098 million gallons per day (Mgal/d), of which Georgia withdrew 82 percent and Florida and Alabama each withdrew 9 percent. Power generation is the single largest water use. Sixteen of the basin's 22 power generating plants are located along the mainstem of the Chattahoochee River. The U.S. Army Corps of Engineers maintains a navigation channel from the mouth of the Apalachicola River to Columbus, Ga., on the Chattahoochee River and to Bainbridge, Ga., on the Flint River. Water quality in the basin is influenced by the operation of 137 municipal wastewater-treatment facilities. In 1990, 354 Mgal/d of municipal wastewater was discharged within the ACF River basin. Eighty-eight percent of the wastewater was discharged into the Chattahoochee River basin, 10.6 percent into the Flint River basin, and 1.4 percent into the Apalachicola River basin. Two-thirds of the 938 stream miles in the Georgia portion of the ACF River basin having water quality that does not meet or only partially meets the designated-use criteria in the Chattahoochee River basin. The Chattahoochee River is the most heavily-used water resource both in the ACF River basin and in Georgia. Urban runoff or unknown nonpoint sources are cited as the causes of water-quality regulations in 72 percent of violations. The remaining causes primarily are combined sewer overflows in the Atlanta area, and discharges from municipal or industrial treatment facilities with inadequate treatment capabilities or operational deficiencies.

Alabama, Florida, Georgia↗

USGS2006

U.S. Geological Survey Chesapeake Bay Studies: Scientific Solutions for a Healthy Bay and Watershed

The U.S. Geological Survey (USGS), the science agency for the Department of Interior (DOI), has the critical role of providing objective science to document and understand ecosystem change in the Chesapeake Bay and its watershed. The human population in the Bay watershed , which grew from 8.1 million in 1950 to almost 16 million in 2000, has resulted in degraded water quality, loss of habitat, and declines in fish and bird populations. USGS scientists are leaders in understanding cause and effect of human activities and natural changes on water quality and the health of the ecosystem. The USGS interacts with resource managers and policy makers to use the science to adapt approaches for implementation, and assess effectiveness of, management actions for ecosystem conservation, restoration, and sustainability. Since the mid-1980s, the USGS has been an active partner in the Chesapeake Bay Program (CBP) , a multi-agency partnership led by the U.S. Environmental Protection Agency, working to achieve the restoration goals set forth in the Chesapeake 2000 agreement . This agreement established over 100 restoration commitments to be addressed by 2010. In 2005, which was the mid-point of the agreement, there was growing concern at all levels of government and by the public that ecological conditions in the Bay and its watershed had not significantly improved. The slow rate of improvement, coupled with the projected impact of human-population increase in the Bay watershed (fig. 1) , implied that many desired ecological conditions will not be achieved by 2010. To address these challenges, the USGS wrote a new science plan for 2006-2011 , and is synthesizing key findings to highlight the accomplishments from science activities for 2000-2005.

Delaware, Maryland, New York, Pennsylvania, Virgin↗

USGS2026

PFAS contamination in Florida estuarine fishes: Levels, patterns, and estimated human and ecological health risks

Per- and polyfluoroalkyl substances (PFAS) pose a significant health threat due to their environmental persistence and toxicity. While PFAS contamination is widespread in Florida, the state currently lacks fish consumption advisories (FCAs) for these compounds, despite existing FCAs for legacy pollutants. This study quantified 40 PFAS in edible muscle tissue from 264 fish (16 species) across four estuaries along Florida's Atlantic coast to assess ecological and human health risks. The highest concentrations of total PFAS were found in Red Drum ( Sciaenops ocellatus ; 0.209 – 51.6 ng/g wet weight) and Spotted Seatrout ( Cynoscion nebulosus; 2.01 – 24.3 ng/g ww) in the Indian River Lagoon, where up to 68% of Red Drum and 75% of Spotted Seatrout exceeded ecological quality standards, indicating potential impacts on predators. PFOS was the predominant PFAS, driving ecological and human health risks. Estimated daily intakes (EDIs) of PFOS exceeded the EPA reference dose (RfD) by up to 3 orders of magnitude, with the highest exposures concentrated in Red Drum and Spotted Seatrout from the Indian River Lagoon. These findings highlight that PFAS monitoring of tissue concentrations in fish across Florida's freshwater and marine systems would be needed for accurately quantifying exposure risks. Such efforts are fundamental to informing regulatory frameworks regarding FCAs and ensuring the long-term protection of aquatic ecosystems and human health.

Florida↗

USGS2018

Understanding the influence of nutrients on stream ecosystems in agricultural landscapes

Sustaining the quality of the Nation’s water resources and the health of our diverse ecosystems depends on the availability of sound water-resources data and information to develop effective, science-based policies. Effective management of water resources also brings more certainty and efficiency to important economic sectors. Taken together, these actions lead to immediate and long-term economic, social, and environmental benefits that make a difference to the lives of the almost 400 million people projected to live in the United States by 2050. In 1991, Congress established the U.S. Geological Survey (USGS) National Water-Quality Assessment (NAWQA) to address where, when, why, and how the Nation’s water quality has changed, or is likely to change in the future, in response to human activities and natural factors. Since then, NAWQA has been a leading source of scientific data and knowledge used by national, regional, State, and local agencies to develop science-based policies and management strategies to improve and protect water resources used for drinking water, recreation, irrigation, energy development, and ecosystem needs ( https://water.usgs.gov/nawqa/applications/ ). Plans for the third decade of NAWQA (2013–23) address priority water-quality issues and science needs identified by NAWQA stakeholders, such as the Advisory Committee on Water Information and the National Research Council, and are designed to meet increasing challenges related to population growth, increasing needs for clean water, and changing land-use and weather patterns. Excess nutrients are a pervasive problem of streams, lakes, and coastal waters. The current report, “The Quality of Our Nation’s Waters—Understanding the Effects of Nutrients on Stream Ecosystems in Agricultural Landscapes,” presents a summary of results from USGS investigations conducted from 2003 to 2011 on processes that influence nutrients and how nutrient enrichment can alter biological components of agricultural streams. This study included collecting data from 232 sites distributed among eight study areas. This report summarizes findings on processes that influence nutrients and how nutrient enrichment can alter biological communities in agricultural streams. These findings are relevant to local, State, regional, and national decision-makers involved in efforts to (1) better understand the influence of nutrients on agricultural streams, (2) develop nutrient criteria for streams and rivers, (3) reduce nutrients to streams and downstream receiving waters, and (4) develop tools for tracking nutrient and biological conditions following nutrient reduction strategies. All NAWQA reports are available online at https://water.usgs.gov/nawqa/bib/ . We hope this publication will provide you with insights and information to meet your water-resource needs and will foster increased citizen awareness and involvement in the protection and restoration of our Nation’s waters. The information in this report is intended primarily for those interested or involved in resource management and protection, conservation, regulation, and policymaking at the regional and national levels.

Central Columbia-Yakima River Basins, Great River ↗

USGS2014

Mercury in fishes from 21 national parks in the Western United States: inter- and intra-park variation in concentrations and ecological risk

Mercury (Hg) is a global contaminant and human activities have increased atmospheric Hg concentrations 3- to 5-fold during the past 150 years. This increased release into the atmosphere has resulted in elevated loadings to aquatic habitats where biogeochemical processes promote the microbial conversion of inorganic Hg to methylmercury, the bioavailable form of Hg. The physicochemical properties of Hg and its complex environmental cycle have resulted in some of the most remote and protected areas of the world becoming contaminated with Hg concentrations that threaten ecosystem and human health. The national park network in the United States is comprised of some of the most pristine and sensitive wilderness in North America. There is concern that via global distribution, Hg contamination could threaten the ecological integrity of aquatic communities in the parks and the wildlife that depends on them. In this study, we examined Hg concentrations in non-migratory freshwater fish in 86 sites across 21 national parks in the Western United States. We report Hg concentrations of more than 1,400 fish collected in waters extending over a 4,000 kilometer distance, from Alaska to the arid Southwest. Across all parks, sites, and species, fish total Hg (THg) concentrations ranged from 9.9 to 1,109 nanograms per gram wet weight (ng/g ww) with a mean of 77.7 ng/g ww. We found substantial variation in fish THg concentrations among and within parks, suggesting that patterns of Hg risk are driven by processes occurring at a combination of scales. Additionally, variation (up to 20-fold) in site-specific fish THg concentrations within individual parks suggests that more intensive sampling in some parks will be required to effectively characterize Hg contamination in western national parks. Across all fish sampled, only 5 percent had THg concentrations exceeding a benchmark (200 ng/g ww) associated with toxic responses within the fish themselves. However, Hg concentrations in 35 percent of fish sampled were above a benchmark for risk to highly sensitive avian consumers (90 ng/g ww), and THg concentrations in 68 percent of fish sampled were above exposure levels recommended by the Great Lakes Advisory Group (50 ng/g ww) for unlimited consumption by humans. Of the fish assessed for risk to human consumers (that is, species that are large enough to be consumed by recreational or subsistence anglers), only one individual fish from Yosemite National Park had a muscle Hg concentration exceeding the benchmark (950 ng/g ww) at which no human consumption is advised. Zion, Capital Reef, Wrangell-St. Elias, and Lake Clark National Parks all contained sites in which most fish exceeded benchmarks for the protection of human and wildlife health. This finding is particularly concerning in Zion and Capitol Reef National Parks because the fish from these parks were speckled dace, a small, invertebrate-feeding species, yet their Hg concentrations were as high or higher than those in the largest, long-lived predatory species, such as lake trout. Future targeted research and monitoring across park habitats would help identify patterns of Hg distribution across the landscape and facilitate management decisions aimed at reducing the ecological risk posed by Hg contamination in sensitive ecosystems protected by the National Park Service.

Alaska;Arizona;California;Colorado;Idaho;Montana;N↗