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At least 649 records · Page 36Linked to original sources
USGS2015

Empirical evaluation of the conceptual model underpinning a regional aquatic long-term monitoring program using causal modelling

Conceptual models are an integral facet of long-term monitoring programs. Proposed linkages between drivers, stressors, and ecological indicators are identified within the conceptual model of most mandated programs. We empirically evaluate a conceptual model developed for a regional aquatic and riparian monitoring program using causal models (i.e., Bayesian path analysis). We assess whether data gathered for regional status and trend estimation can also provide insights on why a stream may deviate from reference conditions. We target the hypothesized causal pathways for how anthropogenic drivers of road density, percent grazing, and percent forest within a catchment affect instream biological condition. We found instream temperature and fine sediments in arid sites and only fine sediments in mesic sites accounted for a significant portion of the maximum possible variation explainable in biological condition among managed sites. However, the biological significance of the direct effects of anthropogenic drivers on instream temperature and fine sediments were minimal or not detected. Consequently, there was weak to no biological support for causal pathways related to anthropogenic drivers’ impact on biological condition. With weak biological and statistical effect sizes, ignoring environmental contextual variables and covariates that explain natural heterogeneity would have resulted in no evidence of human impacts on biological integrity in some instances. For programs targeting the effects of anthropogenic activities, it is imperative to identify both land use practices and mechanisms that have led to degraded conditions (i.e., moving beyond simple status and trend estimation). Our empirical evaluation of the conceptual model underpinning the long-term monitoring program provided an opportunity for learning and, consequently, we discuss survey design elements that require modification to achieve question driven monitoring, a necessary step in the practice of adaptive monitoring. We suspect our situation is not unique and many programs may suffer from the same inferential disconnect. Commonly, the survey design is optimized for robust estimates of regional status and trend detection and not necessarily to provide statistical inferences on the causal mechanisms outlined in the conceptual model, even though these relationships are typically used to justify and promote the long-term monitoring of a chosen ecological indicator. Our application demonstrates a process for empirical evaluation of conceptual models and exemplifies the need for such interim assessments in order for programs to evolve and persist.

California, Colorado, Idaho, Montana, Nevada, Oreg↗
USGS2014

Freshwater mussels of Florida

An exhaustive guide to all aspects of the freshwater mussel fauna in Florida, Freshwater Mussels of Florida covers the ecology, biology, distribution, and conservation of the many species of bivalve mollusks in the Sunshine State. In the past three decades, researchers, the public, businesses that depend on wildlife, and policy makers have given more attention to the threatened natural diversity of the Southeast, including freshwater mussels. This compendium meets the increasingly urgent need to catalog this imperiled group of aquatic organisms in the United States.

Florida↗
USGS2020

Mountain stoneflies may tolerate warming streams: Evidence from organismal physiology and gene expression

Rapid glacier recession is altering the physical conditions of headwater streams. Stream temperatures are predicted to rise and become increasingly variable, putting entire meltwater-associated biological communities at risk of extinction. Thus, there is a pressing need to understand how thermal stress affects mountain stream insects, particularly where glaciers are likely to vanish on contemporary timescales. In this study, we measured the critical thermal maximum (CT MAX ) of stonefly nymphs representing multiple species and a range of thermal regimes in the high Rocky Mountains, USA. We then collected RNA-sequencing data to assess how organismal thermal stress translated to the cellular level. Our focal species included the meltwater stonefly, Lednia tumana , which was recently listed under the U.S. Endangered Species Act due to climate-induced habitat loss. For all study species, critical thermal maxima (CT MAX > 20°C) far exceeded the stream temperatures mountain stoneflies experience (<10°C). Moreover, while evidence for a cellular stress response was present, we also observed constitutive expression of genes encoding proteins known to underlie thermal stress (i.e., heat shock proteins) even at low temperatures that reflected natural conditions. We show that high-elevation aquatic insects may not be physiologically threatened by short-term exposure to warm temperatures and that longer-term physiological responses or biotic factors (e.g., competition) may better explain their extreme distributions.

Global Change Biology↗
USGS2016

Understanding environmental DNA detection probabilities: A case study using a stream-dwelling char Salvelinus fontinalis

Environmental DNA sampling (eDNA) has emerged as a powerful tool for detecting aquatic animals. Previous research suggests that eDNA methods are substantially more sensitive than traditional sampling. However, the factors influencing eDNA detection and the resulting sampling costs are still not well understood. Here we use multiple experiments to derive independent estimates of eDNA production rates and downstream persistence from brook trout ( Salvelinus fontinalis ) in streams. We use these estimates to parameterize models comparing the false negative detection rates of eDNA sampling and traditional backpack electrofishing. We find that using the protocols in this study eDNA had reasonable detection probabilities at extremely low animal densities (e.g., probability of detection 0.18 at densities of one fish per stream kilometer) and very high detection probabilities at population-level densities (e.g., probability of detection > 0.99 at densities of &ge; 3 fish per 100 m). This is substantially more sensitive than traditional electrofishing for determining the presence of brook trout and may translate into important cost savings when animals are rare. Our findings are consistent with a growing body of literature showing that eDNA sampling is a powerful tool for the detection of aquatic species, particularly those that are rare and difficult to sample using traditional methods.

Montana↗
USGS2005

Hydrogeologic framework and water quality of the Vermont Army National Guard Ethan Allen Firing Range, northern Vermont, October 2002 through December 2003

The Ethan Allen Firing Range of the Vermont Army National Guard is a weapons-testing and training facility in a mountainous region of Vermont that has been in operation for about 80 years. The hydrologic framework and water quality of the facility were assessed between October 2002 and December 2003. As part of the study, streamflow was continuously measured in the Lee River and 24 observation wells were installed at 19 locations in the stratified drift and bedrock aquifers to examine the hydrogeology. Chemical analyses of surface water, ground water, streambed sediment, and fish tissue were collected to assess major ions, trace elements, nutrients, and volatile and semivolatile compounds. Sampling included 5 surface-water sites sampled during moderate and low-flow conditions; streambed-sediment samples collected at the 5 surface-water sites; fish-tissue samples collected at 3 of the 5 surface-water sites; macroinvertebrates collected at 4 of the 5 surface-water sites; and ground-water samples collected from 10 observation wells, and samples collected at all surface- and ground-water sites. The hydrogeologic framework at the Ethan Allen Firing Range is dominated by the upland mountain and valley setting of the site. Bedrock wells yield low to moderate amounts of water (0 to 23 liters per minute). In the narrow river valleys, layered stratified-drift deposits of sand and gravel of up to 18 meters thick fill the Lee River and Mill Brook Valleys. In these deposits, the water table is generally within 3 meters below the land surface and overall ground-water flow is from east to west. Streamflow in the Lee River averaged 0.72 cubic meters per second (25.4 cubic feet per second) between December 2002 and December 2003. Streams are highly responsive to precipitation events in this mountainous environment and a comparison with other nearby watersheds shows that Lee River maintains relatively high streamflow during dry periods. Concentrations of trace elements and nutrients in surface-water samples are well below freshwater-quality guidelines for the protection of aquatic life. Brook-trout samples collected in 1992 and 2003 show trace-metal concentrations have decreased over the past 11 years. concentrations in water samples are well below levels that restrict swimming at all five stream sites at moderate and low-flow conditions and in all observation wells. Comparisons among surface-water, streambed-sediment, and biological samples collected in 2003 to earlier studies at the Ethan Allen Firing Range indicate water-quality conditions are similar or have improved over the past 15 years. Ground water in the stratified-drift aquifers at the facility is well buffered with relatively high alkalinities and pH greater than 6. Concentrations of arsenic, cadmium, chromium, lead, nickel, uranium, and zinc were below detection levels in ground-water samples. Barium, cobalt, copper, iron, manganese, molybdenum, and strontium were the only trace elements detected in ground-water samples. Cobalt and iron were detected at low levels in two wells near Mill Brook, and copper was detected at the detection limit in one of these wells. These same two wells had concentrations of barium and manganese 2 to 10 times greater than other ground-water samples. Concentrations of nutrients are at or below detection levels in most ground-water samples. Volatile organic compounds and semivolatile organic compounds were not detected in any water samples from the Ethan Allen Firing Range.

Scientific Investigations Report↗
USGS2006

Pesticide toxicity index for freshwater aquatic organisms, 2nd edition

The U.S. Geological Survey's National Water-Quality Assessment (NAWQA) Program is designed to assess current water-quality conditions, changes in water quality over time, and the effects of natural and human factors on water quality for the Nation's streams and ground-water resources. For streams, one of the most difficult parts of the assessment is to link chemical conditions to effects on aquatic biota, particularly for pesticides, which tend to occur in streams as complex mixtures with strong seasonal patterns. A Pesticide Toxicity Index (PTI) was developed that combines pesticide exposure of aquatic biota (measured concentrations of pesticides in stream water) with acute toxicity estimates (standard endpoints from laboratory bioassays) to produce a single index value for a sample or site. The development of the PTI was limited to pesticide compounds routinely measured in NAWQA studies and to toxicity data readily available from existing databases. Qualifying toxicity data were found for one or more types of test organisms for 124 of the 185 pesticide compounds measured in NAWQA samples, but with a wide range of available bioassays per compound (1 to 232). In the databases examined, there were a total of 3,669 bioassays for the 124 compounds, including 398 48-hour EC50 values (concentration at which 50 percent of test organisms exhibit a sublethal response) for freshwater cladocerans, 699 96-hour LC50 values (concentration lethal to 50 percent of test organisms) for freshwater benthic invertebrates, and 2,572 96-hour LC50 values for freshwater fish. The PTI for a particular sample is the sum of toxicity quotients (measured concentration divided by the median toxicity concentration from bioassays) for each detected pesticide, and thus, is based on the concentration addition model of pesticide toxicity. The PTI can be calculated for specific groups of pesticides and for specific taxonomic groups. Although the PTI does not determine whether water in a sample is toxic to aquatic organisms, its values can be used to rank or compare the toxicity of samples or sites on a relative basis for use in further analysis or additional assessments. The PTI approach may be useful as a basis for comparing the potential significance of pesticides in different streams on a common basis, for evaluating relations between pesticide exposure and observed biological conditions, and for prioritizing where further studies are most needed.

Scientific Investigations Report↗
USGS2018

Monitoring stream temperatures—A guide for non-specialists

Executive Summary Water temperature influences most physical and biological processes in streams, and along with streamflows is a major driver of ecosystem processes. Collecting data to measure water temperature is therefore imperative, and relatively straightforward. Several protocols exist for collecting stream temperature data, but these are frequently directed towards specialists. This document was developed to address the need for a protocol intended for non-specialists (non-aquatic) staff. It provides specific step-by-step procedures on (1) how to launch data loggers, (2) check the factory calibration of data loggers prior to field use, (3) how to install data loggers in streams for year-round monitoring, (4) how to download and retrieve data loggers from the field, and (5) how to input project data into organizational databases.

Techniques and Methods↗
USGS2013

Environmental factors that influence cyanobacteria and geosmin occurrence in reservoirs

Phytoplankton are small to microscopic, free-floating algae that inhabit the open water of freshwater, estuarine, and saltwater systems. In freshwater lake and reservoirs systems, which are the focus of this chapter, phytoplankton communities commonly consist of assemblages of the major taxonomic groups, including green algae, diatoms, dinoflagellates, and cyanobacteria. Cyanobacteria are a diverse group of single-celled organisms that can exist in a wide range of environments, not just open water, because of their adaptability [1-3]. It is the adaptability of cyanobacteria that enables this group to dominate the phytoplankton community and even form nuisance or harmful blooms under certain environmental conditions [3-6]. In fact, cyanobacteria are predicted to adapt favorably to future climate change in freshwater systems compared to other phytoplankton groups because of their tolerance to rising temperatures, enhanced vertical thermal stratification of aquatic ecosystems, and alterations in seasonal and interannual weather patterns [7, 8]. Understanding those environmental conditions that favor cyanobacterial dominance and bloom formation has been the focus of research throughout the world because of the concomitant production and release of nuisance and toxic cyanobacterial-derived compounds [4-6, 7-10]. However, the complex interaction among the physical, chemical, and biological processes within lakes, reservoirs, and large rivers often makes it difficult to identify primary environmental factors that cause the production and release of these cyanobacterial by-products.

South Carolina↗
USGS2002

Assessment of stream quality using biological indices at selected sites in the Delaware River basin, Chester County, Pennsylvania, 1981-97

Introduction In 1970, the Chester County Water Resources Authority (Penn-sylvania) and the U.S. Geological Survey (USGS) established a long-term water-quality network with the goal of assessing the quality of streams in the county and understanding stream changes in response to urbanization using benthic-macroinvertebrate data. This database represents one of the longest continuous water-quality data sets in the country. Benthic macroinvertebrates are aquatic insects, such as mayflies, caddisflies, riffle beetles, and midges, and other invertebrates that live on the stream bottom. Benthic macroinvertebrates are useful in evaluating stream quality because their habitat preferences and low motility cause them to be affected directly by substances that enter the aquatic system. By evaluating the diversity and community structure of benthic-macroinvertebrate populations, a determination of stream quality can be made. Between 1981 and 1997, the water-quality network consisted of 43 sites in 5 major basins in Chester County—Delaware, Schuylkill, Brandywine, Big Elk and Octoraro, and Red and White Clay. Benthic-macroinvertebrate, water-chemistry, and habitat data were collected each year in October or November during base-flow condition. Using these data, Reif evaluates the overall water-quality condition of Chester County streams. This Fact Sheet summarizes the key findings from Reif for streams in the Delaware River Basin. These streams include Darby Creek (site 17), Crum Creek (site 19), Ridley Creek (sites 20 and 21), East Branch Chester Creek (sites 22-24, and 51), and Goose Creek (site 25). This summary includes an analysis of stream conditions on the basis of benthic-macroinvertebrate samples and an analysis of trends in stream conditions for the 17-year study period.

Fact Sheet↗
USGS2014

Guidelines for use of fishes in research: Revised and expanded

The Guidelines for the Use of Fishes in Research (2014; 2014 Guidelines ), now available through the American fisheries Society (AFS) website and in print from the AFS bookstore, is a resource to aid researchers and regulatory authorities regarding responsible, scientifically valid research on fish and aquatic wildlife. The Guidelines for the Use of Fishes in Field Research (American Society of Ichthyologists and Herpetologists [ASIH] et al. 1987, 1988) emphasized field research and was followed by the 2004 Guidelines including laboratory research topics. Each version of the Guidelines has been jointly endorsed and/or published by the ASIH, the American Institute of Fishery Research Biologists (AIFRB), and AFS--each focusing on the scientific understanding, global conservation, and sustainability of aquatic animals, fisheries, and ecosystems. Changes with time necessitate revisions to make the Guidelines consistent with contemporary practices and scientific literature so to remain relevant as a technical resource. This document provides not only general principles relevant for field and laboratory research endeavors but includes specific requirements for researchers working within the United States and outside of the country. Within the scope of their expertise, the 2014 Uses of Fishers in Research (UFR) Committee members updated and revised sections, resulting in a 90-page 2014 Guidelines having undergone through peer review. As before, topical areas were addressed (see Table of Contents on page 416). Expanded coverage was provided on U.S. and international agencies and programs relevant to research with fishes. The Surgical Procedures and the Marking and Tagging section received special focus by a UFR Subcommittee. Feeds and Feeding and the Administration of Drugs, Biologics and Other Chemicals are just some of the newly added topics. The 2014 Guidelines is user-friendly by way of hyperlinks to external Internet sites, intradocument sections, and tables of acronyms with corresponding terms, low regulatory priority drugs, and Office of International des Epizooties notifiable disease agents. Again, the Institutional Animal Care and Use Committee (IACUC) role is explained, expectations for research are provided, and a brief checklist for IACUC readiness is included. Overall, the ,i>2014 Guidelines is the taxon-specific resource for our professional societies and is a principal document for standards on the care and use of fish and aquatic vertebrates in research.

Fisheries↗
USGS2002

Assessment of stream quality using biological indices at selected sites in the Red Clay and White Clay Creek basins, Chester County, Pennsylvania, 1981-97

In 1970, the Chester County Water Resources Authority (Pennsylvania) and the U.S. Geological Survey (USGS) established a long-term water-quality network with the goal of assessing the quality of streams in the county and understanding stream changes in response to urbanization using benthic-macroinvertebrate data. This database represents one of the longest continuous water-quality data sets in the country. Benthic macroinvertebrates are aquatic insects, such as mayflies, caddisflies, riffle beetles, and midges, and other invertebrates that live on the stream bottom. Benthic macroinvertebrates are useful in evaluating stream quality because their habitat preference and low motility cause them to be affected directly by substances that enter the aquatic system. By evaluating the diversity and community structure of benthic-macroinvertebrate populations, a determination of stream quality can be made. Between 1981 and 1997, the water-quality network consisted of 43 sites in 5 major basins in Chester County—Delaware, Schuylkill, Brandywine, Big Elk and Octoraro, and Red and White Clay. Benthicmacroinvertebrate, water-chemistry, and habitat data were collected each year in October or November during base-flow conditions. Using these data, Reif evaluates the overall water-quality condition of Chester County streams. This Fact Sheet summarizes the key findings from Reif for streams in the Red Clay and White Clay Creek Basins. These streams include East Branch Red Clay Creek (site 26), West Branch Red Clay Creek (site 27), East Branch White Clay Creek (site 28), the Middle Branch White Clay Creek (site 29), and West Branch White Clay Creek (site 30). This summary includes an analysis of stream conditions on the basis of benthic-macroinvertebrate samples and an analysis of trends in stream conditions for the 17-year study period.

Pennsylvania↗
USGS2025

Chapter 6: Climate change, wildlife, and wildlife habitats in the Oregon Coast Range

Climate change is likely to have profound effects on wildlife species within the Oregon Coast Adaptation Partnership (OCAP) assessment area, although the direction and magnitude of effects are likely to vary across species. Increased mean and extreme temperatures, especially during summer, may cause shifts in plant and animal species ranges, reduce habitat for some temperature-sensitive wildlife, alter plant phenology and the timing of available food resources, and affect species interactions (e.g., predation, competition). Altered timing of precipitation, summer drought, loss of fog, increased flooding events, earlier snowmelt, and rising sea level may reduce plant productivity, increase tree mortality, shift plant species composition, and lead to reduced wildlife habitat and habitat quality for some forests, riparian areas, wetlands, meadows, estuaries, and beaches. In addition, increasing frequency and extent of wildfire and insect outbreaks may reduce the extent of late-successional forest, reduce habitat connectivity, and increase the spread of invasive species. The biggest change expected for the assessment area is an increase in area where climatic conditions favor coastal mixed forest and a large reduction in area favoring montane conifer forest. Although actual changes in forest types may not necessarily occur by the end of the 21st century, climate change may add physiological and behavioral stress to wildlife. Some wildlife species will be able to persist in place and adapt to new conditions; some may be able to migrate to find suitable habitat; and some may be greatly reduced or extirpated from the assessment area or even go extinct. Shifts in major tree and shrub species will play a major role in food, den, and cover availability for wildlife. Rising sea level will reduce low-elevation habitats along the coast. An increase in the frequency of high-severity weather events will increase frequency and magnitude of flooding, including debris flow events. Coupled with increased temperatures during summer, this may reduce or fragment important ecosystems for aquatic and semi-aquatic species. Evaluation of the vulnerabilities of nine wildlife species based on literature reviews suggests that each species has life-history attributes that can lead to resilience or vulnerability to climate change effects. Depending on long-term objectives, several broad adaptation strategies focus on protecting refugia, establishing redundant wildlife strongholds with large-scale connectivity, and promoting structural and biological complexity.

Oregon↗
USGS1988

Proceedings of a workshop on the development and evaluation of habitat suitability criteria: A compilation of papers and discussions presented at Colorado State University, Fort Collins, Colorado, December 8-12, 1986

The development of reliable habitat suitability criteria is critical to the successful implementation of the Instream Flow Incremental Methodology (IFIM), or any other habitat based evaluation technology. It is also a fascinating topic of research, for several reasons. First, the “science” of habitat quantification is relatively young. Descriptions of habitat use and partitioning can be traced back to Darwin, if not further. Attempts to actually quantify habitat use can be found predominantly during the last two decades, with most of the activity occurring in about the last five years. Second, this work is challenging because we are usually working with fish or some other organism that lives out of sight in an environment that is foreign to humans. Most of the data collection techniques that have been developed for standard fisheries work are unsuited, without modification, for criteria development. These factors make anyone involved in this type of research a pioneer, of sorts. Pioneers often make new and wonderful discoveries, but they also sometimes get lost. In our opinion, however, there is an even more rewarding aspect to criteria development research. It seems that the field of biology has tended to become increasingly clinical over the years. Criteria development demands the unobtrusive observation of organisms in their natural environment, a fact that allows the biological to be a naturalist and still get paid for it. The relative youth and importance of habitat quantification have resulted in rapid advancements in the state of the art. The expansion of methods is vividly demonstrated simply by comparing the two Instream Flow Information Papers written on the subject in 1978 and in 1986. One of the missions of the Aquatic Systems Branch (formerly the Instream Flow Group) is to serve as a clearinghouse for new techniques and methods. In keeping with this role, a workshop was conducted during December 1986 to discuss current and newly evolving methods for developing and evaluating habitat suitability criteria. Participation in this workshop was largely by invitation only. The objective was to obtain insights into problems and possible solutions to criteria development, from the perspective of professionals closely involved with the subject. These proceedings of that workshop are intended to supplement the information contained in Instream Flow Information Paper 21, "Development and Evaluation of Habitat Suitability Criteria for Use in the Instream Flow Incremental Methodology." The workshop was closely arranged in five sessions, roughly following the outline of Information Paper 21. The first session dealt with various aspects of study design and how they can influence the outcome of a study. Session two investigated techniques for developing criteria from professional judgment, and some of the problems encountered when personal or agency prejudice enters the picture. Session three concentrated on field data collection procedures, whereas session four examined methods of converting field data into curves. Field verification studies were discussed in session five. Each presentation in the workshop was followed by a question and answer period of 15 to 30 minutes. These discussions were recorded, transcribed, and appended to the end of each paper in these proceedings. We have attempted to capture the essence of these discussions as accurately as possible, but hope that the reader can appreciate the difficulty in translating a free-ranging discussion (from a barely audible tape) to something that makes sense in print. These question and answer sessions constitute the peer review for each of the papers. This provides the reader with the unique opportunity to review the interactions between authors and reviewers.

Book↗
USGS2015

Copper toxicity and organic matter: Resiliency of watersheds in the Duluth Complex, Minnesota, USA

We estimated copper (Cu) toxicity in surface water with high dissolved organic matter (DOM) for unmined mineralized watersheds of the Duluth Complex using the Biotic Ligand Model (BLM), which evaluates the effect of DOM, cation competition for biologic binding sites, and metal speciation. A sediment-based BLM was used to estimate stream-sediment toxicity; this approach factors in the cumulative effects of multiple metals, incorporation of metals into less bioavailable sulfides, and complexation of metals with organic carbon. For surface water, the formation of Cu-DOM complexes significantly reduces the amount of Cu available to aquatic organisms. The protective effects of cations, such as calcium (Ca) and magnesium (Mg), competing with Cu to complex with the biotic ligand is likely not as important as DOM in water with high DOM and low hardness. Standard hardness-based water quality criteria (WQC) are probably inadequate for describing Cu toxicity in such waters and a BLM approach may yield more accurate results. Nevertheless, assumptions about relative proportions of humic acid (HA) and fulvic acid (FA) in DOM significantly influence BLM results; the higher the HA fraction, the higher calculated resiliency of the water to Cu toxicity. Another important factor is seasonal variation in water chemistry, with greater resiliency to Cu toxicity during low flow compared to high flow. Based on generally low total organic carbon and sulfur content, and equivalent metal ratios from total and weak partial extractions, much of the total metal concentration in clastic streambedsediments may be in bioavailable forms, sorbed on clays or hydroxide phases. However, organicrich fine-grained sediment in the numerous wetlands may sequester significant amount of metals, limiting their bioavailability. A high proportion of organic matter in waters and some sediments will play a key role in the resiliency of these watersheds to potential additional metal loads associated with future mining operations.

Minnesota↗
USGS2005

Occurrence of fecal-indicator bacteria and protocols for identification of fecal-contamination sources in selected reaches of the West Branch Brandywine Creek, Chester County, Pennsylvania

The presence of fecal-indicator bacteria indicates the potential presence of pathogens originating from the fecal matter of warm-blooded animals. These pathogens are responsible for numerous human diseases ranging from common diarrhea to meningitis and polio. The detection of fecal-indicator bacteria and interpretation of the resultant data are, therefore, of great importance to water-resource managers. Current (2005) techniques used to assess fecal contamination within the fluvial environment primarily assess samples collected from the water column, either as grab samples or as depth- and (or) width-integrated samples. However, current research indicates approximately 99 percent of all bacteria within nature exist as attached, or sessile, bacteria. Because of this condition, most current techniques for the detection of fecal contamination, which utilize bacteria, assess only about 1 percent of the total bacteria within the fluvial system and are, therefore, problematic. Evaluation of the environmental factors affecting the occurrence and distribution of bacteria within the fluvial system, as well as the evaluation and modification of alternative approaches that effectively quantify the larger population of sessile bacteria within fluvial sediments, will present water-resource managers with more effective tools to assess, prevent, and (or) eliminate sources of fecal contamination within pristine and impaired watersheds. Two stream reaches on the West Branch Brandywine Creek in the Coatesville, Pa., region were studied between September 2002 and August 2003. The effects of sediment particle size, climatic conditions, aquatic growth, environmental chemistry, impervious surfaces, sediment and soil filtration, and dams on observed bacteria concentrations were evaluated. Alternative approaches were assessed to better detect geographic sources of fecal contamination including the use of turbidity as a surrogate for bacteria, the modification and implementation of sandbag bacteria samplers, and the use of optical brighteners. For the purposes of this report, sources of bacteria were defined as geographic locations where elevated concentrations of bacteria are observed within, or expected to enter, the main branch of the West Branch Brandywine Creek. Biologic sources (for example, waterfowl) were noted where applicable; however, no specific study of biologic sources (such as bacterial source tracking) was conducted. Data indicated that specific bacterial populations within fluvial sediments could be related to specific particle-size ranges. This relation is likely the result of the reduced porosity and permeability associated with finer sediments and the ability of specific bacteria to tolerate particular environments. Escherichia coli (E. coli) showed a higher median concentration (2,160 colonies per gram of saturated sediment) in the 0.125 to 0.5-millimeter size range of natural sediments than in other ranges, and enterococcus bacteria showed a higher median concentration (61,830 colonies per gram of saturated sediment) in the 0.062 to 0.25-millimeter size range of natural sediments than in other ranges. There were insufficient data to assess the particle-size relation to fecal coliform bacteria and (or) fecal streptococcus bacteria. Climatic conditions were shown to affect bacteria concentrations in both the water column and fluvial sediments. Drought conditions in 2002 resulted in lower overall bacteria concentrations than the more typically wet year of 2003. E. coli concentrations in fluvial sediment along the Coatesville study reach in 2002 had a median concentration of 92 colonies per gram of saturated sediment; in 2003, the median concentration had risen to 4,752 colonies per gram of saturated sediment. Symbiotic relations between bacteria and aquatic growth were likely responsible for increased bacteria concentrations observed within an impoundment area on the Coatesville study reach. This reach showed evidence of elevated aquatic growth and sharp increases in E. coli concentrations from upstream to downstream through the impoundment area in both 2002 and 2003. In 2003, E. coli concentrations within the waters column increased from 940 colonies per 100 milliliters upstream to 6,000 colonies per 100 milliliters at the dam crest. Given that these bacteria likely resulted from natural bacterial regrowth, the use of E. coli as an indicator of fecal contamination was severely impaired. Variable environmental conditions along the West Branch Brandywine Creek made the common field-chemical parameters of specific conductance, temperature, pH, and dissolved oxygen ineffective and (or) impossible to use for the determination of inputs of fecal contamination. Extreme variations in chemical gradients commonly were related to the urban/industrial signature of the watershed. For example, during base-flow sampling in 2002, specific-conductance values exceeding 1,000 microsiemens per centimeter observed in effluent from a local steel mill. This effluent raised the specific conductance within the West Branch Brandywine from just above 200 microsiemens per centimeter upstream from the outfall to just below 500 microsiemens per centimeter downstream from the outfall. These chemical gradients also, likely, had an effect on the initial colonization of bacteria, the formation of biofilms, and the persistence of certain types of bacteria along the study reach. Data collected in 2003 indicated that nutrients increased during both base-flow and stormflow conditions along the Coatesville study reach. For example, during base-flow sampling in 2003, 20 pounds of phosphorus was shown to enter the West Branch Brandywine Creek along the Coatesville study reach. The largest contributors to this base-flow nutrient load were likely two wastewater-treatment facilities adjacent to the study reach. During stormflow sampling in 2003, 480 pounds of phosphorus was shown to enter the West Branch Brandywine Creek along the Coatesville study reach. Data, along with other research, indicated the largest contributor to this stormflow nutrient load was likely remobilized sediment originating from a large dam impoundment. These elevated nutrient concentrations were considered sufficient to promote accelerated aquatic growth along the reach. Data collected in 2003 showed that wastewater constituents entered the West Branch Brandywine Creek largely from urban storm-sewer systems. Samples from the primary storm sewer for the city of Coatesville had detections for 20 of 69 wastewater constituents. These constituents included both strong and weak indicators of fecal contamination and generally indicated the storm-sewer system along the Coatesville study reach was a likely source of fecal-indicator bacteria and fecal contamination under base-flow conditions. By comparison, 5 constituents were detected in samples from the upstream end of the reach, and 10 constituents were detected in samples from the downstream end of the reach. During stormflow, numbers of detections were similar along the entire length of the study reach-five in samples from the upstream end, eight in samples from the center of the reach, and seven in samples from the downstream end of the reach. These data indicate that point sources (such as culverts and pipes, septic systems, and wastewater-treatment facilities) are not likely the origin of bacteria contamination during stormflow. The bacteria concentrations observed during stormflow events probably result from remobilized sessile bacteria stored within fluvial sediments. In this case, these bacteria should not be considered indicators of current fecal contamination. Impervious surfaces were found to increase bacteria concentrations along the West Branch Brandywine Creek because contaminated runoff from impervious areas generally flows into, and is concentrated within, the confines of the local storm-sewer system. During 2002, storm-sewer outfalls draining impervious areas were associated with all major locations of elevated bacterial concentrations (greater than 1,200 colonies per gram of saturated sediment) in fluvial sediments. During 2003, wetter conditions and overall bacteria concentrations higher than in 2002 resulted in point sources of bacterial contamination becoming less pronounced; however, the storm-sewer system, draining adjacent impervious areas, was still observed to be the primary source of bacteria along the reach. Where stormwater and (or) other runoff from these areas was allowed to infiltrate and (or) flow through wetland and riparian buffers, bacteria concentrations were not observed to be elevated above background levels commonly observed throughout similar areas of the same reach. Two run-of-the-river dams along the Coatesville study reach were evaluated for their effects on observed bacterial concentrations. These dams were shown to have greater or lesser effects on bacterial concentrations depending on the size of the structure and the capacity of the structure to impede flows. The smaller upstream dam had an approximate height of 3 feet and showed little observed effect on measured turbidity values; these data indicated that the dam did not effectively impede the flow of water or sediment within the West Branch Brandywine Creek. Consequently, this small dam did not show any observed effect on bacterial concentrations either upstream or downstream of the structure. The larger dam, near the middle of the reach, had an approximate height of 20 feet and showed greater effects on both turbidity and bacteria concentrations. The capacity of the larger dam to impede flows, combined with nutrients entering the reach, resulted in increased biologic activity throughout the impoundment area. Within this larger impoundment, enterococcus bacteria populations were observed to decrease sharply and E. coli bacteria populations were observed to increase sharply as flow approached the dam crest. All bacteria levels were then observed to drop to background levels, in both the water column and fluvial sediment, immediately downstream from the dam crest. Additional study is required to determine the cause for this rapid die off. Turbidity was assessed as a potential surrogate for E. coli bacteria. Regression analysis indicated higher turbidity levels usually can indicate higher concentrations of bacteria (R2 = 0.67), but the relation was too sporadic on the West Branch Brandywine Creek to use turbidity as a surrogate for estimated bacteria concentrations. Evaluation of data from individual base-flow and stormflow events resulted in variable and generally poor statistical relations between E. coli bacteria and turbidity (R2 values ranged from 0.02 to 0.94). Sandbag samplers were used in 2003 to determine their suitability for the assessment of fecal contamination. Sandbag samplers rely on the ability of bacteria to attach to surfaces and use the larger sessile bacteria populations instead of the more commonly used planktonic bacteria populations. E. coli bacteria concentrations observed in the sandbag samplers, after 1 week in place, were similar to those found within natural sediments collected concurrently. Enterococcus bacteria concentrations within the same sandbag samplers were not similar, and were generally lower, than those observed within the natural sediments. This discrepancy was likely because sand within the samplers was sieved to a size that was likely too coarse for enterococcus bacteria to persist. Optical-brightener samplers were installed along with each sandbag sampler. Optical brighteners are additives used in common household detergents; therefore, detection of optical brighteners, along with elevated fecal-indicator bacteria concentrations, strongly indicates a link to humans. Positive results for optical brighteners were detected only at the outfalls of two sewage-treatment facilities; because of treatment of the effluent from these facilities, these samples did not have elevated bacteria concentrations. The lack of additional positive results was largely because this method is not sensitive to low concentrations of optical brighteners.

Pennsylvania↗
USGS2019

Cryptic introduction of water chestnut (Trapa) in the northeastern United States

Trapa natans , characterized by four-horned fruits, has been recognized as an introduced species in the northeastern United States since the 1920′s. However, in 2014 a two-horned morphotype of Trapa was discovered in the Potomac River in Virginia. As such, we hypothesize the two-horned variety represents a cryptic introduction of a Trapa taxon distinct from the four-horned T. natans previously identified in North America. We tested this hypothesis by genotyping 129 amplified fragment length polymorphism loci for 304 Trapa individuals collected from across the Northeast US and several populations from Asia and Africa. The two-horned and four-horned morphotypes in the northeastern US were found to be genetically and morphologically distinct. The two-horned Trapa taxon was most genetically and morphologically similar to samples from Taiwan identified as T. bispinosa Roxb. var iinumai Nakano. The four-horned Trapa taxon previously identified as T. natans was most genetically and morphologically similar to T. natans collected from Japan, but were genetically distinct. Therefore, it is likely that the US four-horned Trapa was introduced from somewhere outside of Japan, an unsampled area in Japan, or have genetically diverged since introduction. Distinguishing these two US Trapa taxa will be important for documenting spread and identifying new populations, and for further study on the timing and efficacy of physical, chemical, and biological control options. Our study also highlights the need for a comprehensive geographic survey of Trapa morphology and genetics to clarify the taxonomy.

Aquatic Botany↗
USGS2007

Myxosoma cerebralis (Myxozoa: Myxosporea) etiologic agent of salmonid whirling disease requires tubificid worm (Annelida: Oligochaetes) in its life cycle

Studies of the life cycle of Myxosoma cerebralis showed that development of infectivity did not occur endogenously but that the spore “aging” process required participation of an aquatic tubificid oligochaete. Data suggestive of such involvement were derived from trials in which spores were “aged” in an array of inert, sterilized, pasteurized, or natural aquatic substrates and from examination of aquatic soils from trout hatcheries in which whirling disease was epizootic. The role of the aquatic oligochaete was confirmed two ways. First, signs of whirling disease developed, and M. cerebralis spores were produced in young rainbow trout ( Salmo gairdneri ) that had been fed oligochaetes harvested from pond soil taken from two hatcheries where whirling disease was epizootic. Second, when containers of pasteurized soil were populated with four genera of oligochaetes– Aeolosoma, Dero, Stylaria , or Tubifex – from a biological supply house, or with tubificid worms from trout hatcheries free of whirling disease, and then seeded with M. cerebralis spores and “aged” for 4 months, whirling disease occurred only in trout held with Tubifex and with hatchery tubificids.

Journal of Protozoology↗
USGS2013

Characterization of hydrodynamic and sediment conditions in the lower Yampa River at Deerlodge Park, east entrance to Dinosaur National Monument, northwest Colorado, 2011

The Yampa River in northwestern Colorado is the largest, relatively unregulated river system in the upper Colorado River Basin. Water from the Yampa River Basin continues to be sought for a number of municipal, industrial, and energy uses. It is anticipated that future water development within the Yampa River Basin above the amount of water development identified under the Upper Colorado River Endangered Fish Recovery Implementation Program and the Programmatic Biological Opinion may require additional analysis in order to understand the effects on habitat and river function. Water development in the Yampa River Basin could alter the streamflow regime and, consequently, could lead to changes in the transport and storage of sediment in the Yampa River at Deerlodge Park. These changes could affect the physical form of the reach and may impact aquatic and riparian habitat in and downstream from Deerlodge Park. The U.S. Geological Survey, in cooperation with the Colorado Water Conservation Board, began a study in 2011 to characterize the current hydrodynamic and sediment-transport conditions for a 2-kilometer reach of the Yampa River in Deerlodge Park. Characterization of channel conditions in the Deerlodge Park reach was completed through topographic surveying, grain-size analysis of streambed sediment, and characterization of streamflow properties. This characterization provides (1) a basis for comparisons of current stream functions (channel geometry, sediment transport, and stream hydraulics) to future conditions and (2) a dataset that can be used to assess channel response to streamflow alteration scenarios indicated from computer modeling of streamflow and sediment-transport conditions.

Colorado↗