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At least 271 records · Page 15Linked to original sources

Gaps in water quality modeling of hydrologic systems

This review assesses gaps in water quality modeling, emphasizing opportunities to improve next-generation models that are essential for managing water quality and are integral to meeting goals of scientific and management agencies. In particular, this paper identifies gaps in water quality modeling capabilities that, if addressed, could support assessments, projections, and evaluations of management alternatives to support ecosystem health and human beneficial use of water resources. It covers surface water and groundwater quality modeling, dealing with a broad suite of physical, biogeochemical, and anthropogenic drivers. Modeling capabilities for six constituents (or constituent categories) are explored: water temperature, salinity, nutrients, sediment, geogenic constituents, and contaminants of emerging concern. Each constituent was followed through the coupled atmospheric-hydrologic-human system, with prominent modeling gaps described for a diverse array of relevant inputs, processes, and human activities. Commonly identified modeling gaps primarily fall under three types: (1) model gaps, (2) data gaps, and (3) process understanding gaps. In addition to potential solutions for addressing specific individual modeling limitations, some broad approaches (e.g., enhanced data collection and compilation, machine learning, reduced-complexity modeling) are discussed as ways forward for tackling multiple gaps. This gap analysis establishes a framework of diverse approaches that may support improved process representation, scale, and accuracy of models for a wide range of water quality issues.

Water↗

Analyzing cloud base at local and regional scales to understand tropical montane cloud forest vulnerability to climate change

The degree to which cloud immersion provides water in addition to rainfall, suppresses transpiration, and sustains tropical montane cloud forests (TMCFs) during rainless periods is not well understood. Climate and land use changes represent a threat to these forests if cloud base altitude rises as a result of regional warming or deforestation. To establish a baseline for quantifying future changes in cloud base, we installed a ceilometer at 100 m altitude in the forest upwind of the TMCF that occupies an altitude range from ∼ 600 m to the peaks at 1100 m in the Luquillo Mountains of eastern Puerto Rico. Airport Automated Surface Observing System (ASOS) ceilometer data, radiosonde data, and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite data were obtained to investigate seasonal cloud base dynamics, altitude of the trade-wind inversion (TWI), and typical cloud thickness for the surrounding Caribbean region. Cloud base is rarely quantified near mountains, so these results represent a first look at seasonal and diurnal cloud base dynamics for the TMCF. From May 2013 to August 2016, cloud base was lowest during the midsummer dry season, and cloud bases were lower than the mountaintops as often in the winter dry season as in the wet seasons. The lowest cloud bases most frequently occurred at higher elevation than 600 m, from 740 to 964 m. The Luquillo forest low cloud base altitudes were higher than six other sites in the Caribbean by ∼ 200–600 m, highlighting the importance of site selection to measure topographic influence on cloud height. Proximity to the oceanic cloud system where shallow cumulus clouds are seasonally invariant in altitude and cover, along with local trade-wind orographic lifting and cloud formation, may explain the dry season low clouds. The results indicate that climate change threats to low-elevation TMCFs are not limited to the dry season; changes in synoptic-scale weather patterns that increase frequency of drought periods during the wet seasons (periods of higher cloud base) may also impact ecosystem health.

Atmospheric Chemistry and Physics↗

A General Lake Model (GLM 3.0) for linking with high-frequency sensor data from the Global Lake Ecological Observatory Network (GLEON)

The General Lake Model (GLM) is a one-dimensional open-source code designed to simulate the hydrodynamics of lakes, reservoirs, and wetlands. GLM was developed to support the science needs of the Global Lake Ecological Observatory Network (GLEON), a network of researchers using sensors to understand lake functioning and address questions about how lakes around the world respond to climate and land use change. The scale and diversity of lake types, locations, and sizes, and the expanding observational datasets created the need for a robust community model of lake dynamics with sufficient flexibility to accommodate a range of scientific and management questions relevant to the GLEON community. This paper summarizes the scientific basis and numerical implementation of the model algorithms, including details of sub-models that simulate surface heat exchange and ice cover dynamics, vertical mixing, and inflow–outflow dynamics. We demonstrate the suitability of the model for different lake types that vary substantially in their morphology, hydrology, and climatic conditions. GLM supports a dynamic coupling with biogeochemical and ecological modelling libraries for integrated simulations of water quality and ecosystem health, and options for integration with other environmental models are outlined. Finally, we discuss utilities for the analysis of model outputs and uncertainty assessments, model operation within a distributed cloud-computing environment, and as a tool to support the learning of network participants.

Geoscientific Model Development↗

The roles of large top predators in coastal ecosystems: new insights from long term ecological research

During recent human history, human activities such as overhunting and habitat destruction have severely impacted many large top predator populations around the world. Studies from a variety of ecosystems show that loss or diminishment of top predator populations can have serious consequences for population and community dynamics and ecosystem stability. However, there are relatively few studies of the roles of large top predators in coastal ecosystems, so that we do not yet completely understand what could happen to coastal areas if large top predators are extirpated or significantly reduced in number. This lack of knowledge is surprising given that coastal areas around the globe are highly valued and densely populated by humans, and thus coastal large top predator populations frequently come into conflict with coastal human populations. This paper reviews what is known about the ecological roles of large top predators in coastal systems and presents a synthesis of recent work from three coastal eastern US Long Term Ecological Research (LTER) sites where long-term studies reveal what appear to be common themes relating to the roles of large top predators in coastal systems. We discuss three specific themes: (1) large top predators acting as mobile links between disparate habitats, (2) large top predators potentially affecting nutrient and biogeochemical dynamics through localized behaviors, and (3) individual specialization of large top predator behaviors. We also discuss how research within the LTER network has led to enhanced understanding of the ecological roles of coastal large top predators. Highlighting this work is intended to encourage further investigation of the roles of large top predators across diverse coastal aquatic habitats and to better inform researchers and ecosystem managers about the importance of large top predators for coastal ecosystem health and stability.

Florida;Georgia;Massachusetts↗

Harmful algal blooms in the Alaskan Arctic: An emerging threat as oceans warm

Harmful algal blooms (HABs) present an emerging threat to human and ecosystem health in the Alaskan Arctic. Two HAB toxins are of concern in the region: saxitoxins (STXs), a family of compounds produced by the dinoflagellate Alexandrium catenella , and domoic acid (DA), produced by multiple species in the diatom genus Pseudo-nitzschia . These potent neurotoxins cause paralytic and amnesic shellfish poisoning, respectively, in humans, and can accumulate in marine organisms through food web transfer, causing illness and mortality among a suite of wildlife species. With pronounced warming in the Arctic, along with enhanced transport of cells from southern waters, there is significant potential for more frequent and larger HABs of both types. STXs and DA have been detected in the tissues of a range of marine organisms in the region, many of which are important food resources for local residents. The unique nature of the Alaskan Arctic, including difficult logistical access, lack of response infrastructure, and reliance of coastal populations on the noncommercial acquisition of marine resources for nutritional, cultural, and economic well-being, poses urgent and significant challenges as this region warms and the potential for impacts from HABs expands.

Oceanography↗

Physiological and gene transcription assays to assess responses of mussels to environmental changes

Coastal regions worldwide face increasing management concerns due to natural and anthropogenic forces that have the potential to significantly degrade nearshore marine resources. The goal of our study was to develop and test a monitoring strategy for nearshore marine ecosystems in remote areas that are not readily accessible for sampling. Mussel species have been used extensively to assess ecosystem vulnerability to multiple, interacting stressors. We sampled bay mussels ( Mytilus trossulus ) in 2015 and 2016 from six intertidal sites in Lake Clark and Katmai National Parks and Preserves, in south-central Alaska. Reference ranges for physiological assays and gene transcription were determined for use in future assessment efforts. Both techniques identified differences among sites, suggesting influences of both large-scale and local environmental factors and underscoring the value of this combined approach to ecosystem health monitoring.

Alaska↗

Estimation of stream salamander (Plethodontidae, Desmognathinae and Plethodontinae) populations in Shenandoah National Park, Virginia, USA

Stream salamanders in the family Plethodontidae constitute a large biomass in and near headwater streams in the eastern United States and are promising indicators of stream ecosystem health. Many studies of stream salamanders have relied on population indices based on counts rather than population estimates based on techniques such as capture-recapture and removal. Application of estimation procedures allows the calculation of detection probabilities (the proportion of total animals present that are detected during a survey) and their associated sampling error, and may be essential for determining salamander population sizes and trends. In 1999, we conducted capture-recapture and removal population estimation methods for Desmognathus salamanders at six streams in Shenandoah National Park, Virginia, USA. Removal sampling appeared more efficient and detection probabilities from removal data were higher than those from capture-recapture. During 2001-2004, we used removal estimation at eight streams in the park to assess the usefulness of this technique for long-term monitoring of stream salamanders. Removal detection probabilities ranged from 0.39 to 0.96 for Desmognathus, 0.27 to 0.89 for Eurycea and 0.27 to 0.75 for northern spring (Gyrinophilus porphyriticus) and northern red (Pseudotriton ruber) salamanders across stream transects. Detection probabilities did not differ across years for Desmognathus and Eurycea, but did differ among streams for Desmognathus. Population estimates of Desmognathus decreased between 2001-2002 and 2003-2004 which may be related to changes in stream flow conditions. Removal-based procedures may be a feasible approach for population estimation of salamanders, but field methods should be designed to meet the assumptions of the sampling procedures. New approaches to estimating stream salamander populations are discussed.

Alytes↗

Review of concepts useful for maintaining quality of male reproductive field samples for laboratory study

Investigations into cellular and molecular characteristics of male gametes obtained from fish in natural ecosystems require careful sample handling and shipping in order to minimize artifacts. Maintaining sample integrity engenders confident assessments of ecosystem health, whereby animal condition is often reflected by gamete biomarkers - indicators that respond in measurable ways to changes. A number of our investigations have addressed the hypothesis that biomarkers from fish along a pollution gradient are reflective of site location. Species biology and the selected biological endpoints direct choice of parameters such as: temperature, buffer osmolality, time in transit, fixation, cryoprotectants, protease inhibition, and antibiotic inclusion in extender. This paper will highlight case studies, and outline parameters and thoughts on approaches for use by field and laboratory researchers.

Conference Paper↗

Nature's Notebook 2011: Data & participant summary

Introduction The USA National Phenology Network The USA National Phenology Network (USA‐NPN; www.usanpn.org) seeks to engage a diverse range of citizen scientist volunteers, federal, state, and non‐governmental organizations, educators and professional research scientists to collect phenological observations of plants and animals using consistent standards and to contribute their observations to a national data repository. To guide this effort, the USA‐NPN National Coordinating Office (NCO), based in Tucson, Arizona, implemented an online monitoring program for plants and animals, Nature's Notebook , and has developed phenology monitoring protocols and an information management system, which includes the National Phenology Database (NPDb). We are developing a diversity of materials, tools, techniques, and protocols to assist decision making and education related to ecology, wildlife, human health, ecosystem services, natural resource management, biological conservation, and climate change adaptation.

USA-NPN Technical Series↗

A science-based, watershed strategy to support effective remediation of abandoned mine lands

A U.S. Geological Survey Abandoned Mine Lands Initiative will develop a strategy for gathering and communicating the scientific information needed to formulate effective and cost-efficient remediation of abandoned mine lands. A watershed approach will identify, characterize, and remediate contaminated sites that have the most profound effect on water and ecosystem quality within a watershed. The Initiative will be conducted during 1997 through 2001 in two pilot watersheds, the Upper Animas River watershed in Colorado and the Boulder River watershed in Montana. Initiative efforts are being coordinated with the U.S. Forest Service, Bureau of Land Management, National Park Service, and other stakeholders which are using the resulting scientific information to design and implement remediation activities. The Initiative has the following eight objective-oriented components: estimate background (pre-mining) conditions; define baseline (current) conditions; identify target sites (major contaminant sources); characterize target sites and processes affecting contaminant dispersal; characterize ecosystem health and controlling processes at target sites; develop remediation goals and monitoring network; provide an integrated, quality-assured and accessible data network; and document lessons learned for future applications of the watershed approach.

Colorado;Montana↗

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↗

Towards monitoring land-cover and land-use changes at a global scale: the global land survey 2005

Land cover is a critical component of the Earth system, infl uencing land-atmosphere interactions, greenhouse gas fl uxes, ecosystem health, and availability of food, fi ber, and energy for human populations. The recent Integrated Global Observations of Land (IGOL) report calls for the generation of maps documenting global land cover at resolutions between 10m and 30m at least every fi ve years (Townshend et al., in press). Moreover, despite 35 years of Landsat observations, there has not been a unifi ed global analysis of land-cover trends nor has there been a global assessment of land-cover change at Landsat-like resolution. Since the 1990s, the National Aeronautics and Space Administration (NASA) and the U.S. Geological Survey (USGS) have supported development of data sets based on global Landsat observations (Tucker et al., 2004). These land survey data sets, usually referred to as GeoCover ™, provide global, orthorectifi ed, typically cloud-free Landsat imagery centered on the years 1975, 1990, and 2000, with a preference for leaf-on conditions. Collectively, these data sets provided a consistent set of observations to assess land-cover changes at a decadal scale. These data are freely available via the Internet from the USGS Center for Earth Resources Observation and Science (EROS) (see http://earthexplorer.usgs.gov or http://glovis.usgs.gov). This has resulted in unprecedented downloads of data, which are widely used in scientifi c studies of land-cover change (e.g., Boone et al., 2007; Harris et al., 2005; Hilbert, 2006; Huang et al. 2007; Jantz et al., 2005, Kim et al., 2007; Leimgruber, 2005; Masek et al., 2006). NASA and USGS are continuing to support land-cover change research through the development of GLS2005 - an additional global Landsat assessment circa 20051 . Going beyond the earlier initiatives, this data set will establish a baseline for monitoring changes on a 5-year interval and will pave the way toward continuous global land-cover monitoring at Landsat-like resolution in the next decade.

Photogrammetric Engineering and Remote Sensing↗

Assessing the vulnerability of human and biological communities to changing ecosystem services using a GIS-based multi-criteria decision support tool

In this paper we describe an application of a GIS-based multi-criteria decision support web tool that models and evaluates relative changes in ecosystem services to policy and land management decisions. The Santa Cruz Watershed Ecosystem Portfolio (SCWEPM) was designed to provide credible forecasts of responses to ecosystem drivers and stressors and to illustrate the role of land use decisions on spatial and temporal distributions of ecosystem services within a binational (U.S. and Mexico) watershed. We present two SCWEPM sub-models that when analyzed together address bidirectional relationships between social and ecological vulnerability and ecosystem services. The first model employs the Modified Socio-Environmental Vulnerability Index (M-SEVI), which assesses community vulnerability using information from U.S. and Mexico censuses on education, access to resources, migratory status, housing situation, and number of dependents. The second, relating land cover change to biodiversity (provisioning services), models changes in the distribution of terrestrial vertebrate habitat based on multitemporal vegetation and land cover maps, wildlife habitat relationships, and changes in land use/land cover patterns. When assessed concurrently, the models exposed some unexpected relationships between vulnerable communities and ecosystem services provisioning. For instance, the most species-rich habitat type in the watershed, Desert Riparian Forest, increased over time in areas occupied by the most vulnerable populations and declined in areas with less vulnerable populations. This type of information can be used to identify ecological conservation and restoration targets that enhance the livelihoods of people in vulnerable communities and promote biodiversity and ecosystem health.

Santa Cruz watershed↗

History and effects of hatchery salmon in the Pacific

There has been a long history of production of hatchery salmon along the Pacific coast - from California’s first efforts in the 1870s using eggs from chinook and rainbow trout to the recent large-scale production hatcheries for pink salmon in Japan and the Russian Far East. The rationale for this production has also varied from replacement of fish lost in commercial ocean harvests to mitigation and restoration of salmon in areas where extensive habitat alteration has reduced salmonid viability and abundance. Over the years, we have become very successful in producing a certain type of product from salmon hatcheries, but until recently we seldom questioned the impacts the production and release of hatchery fish may have on freshwater and marine aquatic ecosystems and on the sustainability of sympatric wild salmon populations. This paper addresses the history of hatcheries around the Pacific Rim and considers potential negative implications of hatchery-produced salmon through discussions of biological impacts and biodiversity, ecological impacts and competitive displacement, fish and ecosystem health, and genetic impacts of hatchery fish as threats to wild populations of Pacific salmon.

Speaking for the Salmon↗

Variation in spring nearshore resident fish species composition and life histories in the lower San Joaquin watershed and delta

Providing freshwater to human populations while protecting or rehabilitating ecosystem health is a significant challenge to water resource managers and requires accurate knowledge of aquatic resources. Previous studies of fish assemblages in the San Francisco Estuary and watershed have focused on specific habitat types, water bodies, or geographic subregions. In this study, we use seining data from two monitoring programs to provide an integrated view of spring nearshore resident fish species composition and life history characteristics in five regions: the San Joaquin River, the upper Sacramento River, the lower Sacramento River, the northern Sacramento-San Joaquin Delta (North Delta), and the Interior Delta. Data for the period March-May from 1994 to 2002, showed that spring species composition of the San Joaquin River was very different from the other four regions. Total catch in the San Joaquin River was dominated by small, short-lived batch spawning alien species (93%), particularly red shiner Cyprinella lutrensis (>75% of total catch). The upper and lower Sacramento River were very similar in species composition and life history characteristics and less dominated by alien fish (<45% of total catch). Ordination of species percentage abundances by non–metric multidimensional scaling confirmed that the major gradient was from assemblages dominated by native species to assemblages dominated by alien species. Two-way analysis of variance of ordination scores indicated that spatial variability was more important than annual variability in explaining patterns in species composition. The potential benefits of San Joaquin River native fish restoration appear high because there is so much potential for improvement; however, it is unclear how to best manipulate the system to achieve such restoration. Addressing such uncertainties is necessary if society desires the reservation and restoration of native biodiversity as human demands on water resources increase.

California↗

Science needs for continued development of total nitrogen deposition budgets in the United States

The objectives of this white paper are to describe the state of the science with respect to total Nr deposition budgets in North America and the research needed to improve these budgets from both a measurement and modeling standpoint. The document is intended to serve as a plan for TDep research activities but also, more broadly, to provide program managers, natural resource managers, policy makers and scientists with an understanding of the need for complete and accurate Nr deposition budgets to protect ecosystem health and human welfare, and the linkages between the underlying policy-relevant science questions and the specific knowledge and data gaps needed to improve Nr deposition budgets.

Report↗

The collection and analysis of Bay of Fundy sediment under contract between the association of US delegates to the Gulf of Maine Council on the marine environment and eastern Charlotte waterways for contaminant monitoring and analysis

This report presents data obtained through the EcoSystem Indicator Partnership (ESIP) which was established in 2006 to improve understanding and to inform researchers, managers, and citizens about the status and trends of ecosystem health in the Gulf of Maine (http://www.gulfofmaine.org/2/esip-homepage/). In its efforts to compile information on contaminant indicators in the Gulf of Maine, ESIP identified gaps in monitoring information and worked in partnership with the Gulf of Maine Council and other organizations to fill these gaps. The monitoring and data gaps identified by ESIP indicated that data on contaminants in intertidal/subtidal sediments were lacking for the Bay of Fundy. To address this data gap, the Association of US Delegates to the Gulf of Maine Council on the Marine Environment contracted Eastern Charlotte Waterways Inc., an independent non-governmental organization, to conduct a contaminant monitoring and analysis project funded by Environment and Climate Change Canada . This report summarizes the data produced from this sediment analysis project.

Gulf of Maine↗

Cyanotoxin occurrence in the United States: A 20 year retrospective

Cyanobacterial blooms, and associated cyanotoxin occurrence, are a concern because of the potential harms posed to humans, wildlife, and aquatic ecosystem health. Evidence suggests the magnitude, frequency, and duration of cyanobacterial blooms are increasing, and these events represent a significant challenge to freshwaters and, increasingly, marine waters, worldwide. Cyanobacterial blooms routinely receive local and national attention because of occurrence in new locations, recreational closures, drinking-water impacts, animal illnesses and deaths, scientific advances, and novel management and mitigation strategies. Due to public information campaigns at local, state, and federal levels, the public is generally aware of what cyanobacterial blooms look like and potential risks posed to human and animal health. It is difficult now to imagine a time when cyanobacterial blooms were considered an occasional nuisance in lakes and reservoirs, well-known only by limnologists. When I began my career over twenty years ago, however, that was the status. Cyanobacteria were just beginning to capture attention, and they certainly captured mine.

Lakeline↗