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USGS2023

Cryptic declines of small, cold-water specialists highlight potential vulnerabilities of headwater streams as climate refugia

Increasing temperatures and climate-driven disturbances like wildfire are a growing threat to many species, including cold-water specialists. Montane areas and cold streams are often considered climate refugia that buffer communities against change. However, climate refugia are often species-specific, and despite growing awareness that life histories and habitat requirements shape responses to change, small or non-game species are often under-represented in monitoring and planning programs. A recent study in Montana, USA, revealed much larger warming-related declines in occupancy for small, non-game slimy sculpin ( Cottus cognatus ) between 1993 and 1995 and 2011–2013 than for two socially valued salmonid fishes that shape regional conservation efforts. To broaden insight into climate change vulnerabilities of headwater stream communities, we analyzed data for Rocky Mountain tailed frogs ( Ascaphus montanus ) that were collected during those same electrofishing surveys for fishes from 241 stream reaches. Tailed frogs occupy small, cold streams and have several life-history traits that make them sensitive to environmental change. We used a Bayesian framework to estimate occupancy, colonization, and extinction dynamics relative to forest canopy, estimated stream temperature, and wildfire effects. Tailed frog occupancy decreased by 19 % from 1993 to 1995 to 2011–2013. Changes in occupancy were linked with increased extinction and reduced colonization where there were fire-driven reductions in canopy cover, and reduced colonization of stream reaches that warmed on average 0.8 °C during the study. Our results highlight extensive extirpations for oft-overlooked species and emphasize the importance of including species with diverse habitat requirements and life histories in conservation planning.

Idaho, Montana↗

USGS2022

Nekton community dynamics within active and inactive deltas in a major river estuary: Potential implications for altered hydrology regimes

High fisheries production within estuaries is associated with coastal upwelling, tidal mixing, and land-based runoff facing increasing impacts from climate and human activities. Active river deltas receive large riverine inflows compared to inactive river deltas, providing contrasting estuaries to compare impacts of river inflow on estuarine nekton. We quantified nekton assemblages and stable isotopes (δ 13 C, δ 15 N) of commercially important blue crab Callinectes sapidus Rathbun, 1896 within an active and inactive delta in coastal Louisiana to explore the impacts of differing riverine inflow. Crustaceans dominated estuarine assemblages, differing only by season and not delta type, with summer and fall supporting highest densities. Fish density and assemblages differed by the interaction of season and delta due to differences during the 2019 record high spring river inflow. During this period, the active delta supported reduced fish densities and richness compared to the inactive delta. Nekton densities across deltas and seasons reflect a combination of species life history characteristics and habitat conditions. The high spring river discharge in 2019 impacted habitat availability (reduced presence of submerged aquatic vegetation), water conditions (decreased temperature and salinity), and potentially displaced nekton to unsampled habitat areas (i.e. interior marsh surface) within the active delta. While differences in nekton density and assemblages were only evident during the high spring river discharge, δ 15 N values of blue crabs were approximately 1.5 times higher in the active delta, potentially indicating more terrestrial influence. Understanding how altered inflow impacts environmental variables supporting estuarine nekton production remains critical for supporting management within these hydrologically managed regions.

Louisiana↗

USGS2012

An annotated bibliography for lamprey habitat in the White Salmon River, Washington

The October 2011 decommissioning of Condit Dam on the White Salmon River at river kilometer (rkm) 5.3 removed a significant fish passage barrier from the White Salmon River basin for the first time in nearly a century. This affords an opportunity to regain a potentially important drainage basin for Pacific lamprey ( Entosphenus tridentatus ) production. In anticipation of Pacific lamprey recolonization or reintroduction, aquatic resource managers, such as the Yakama Nation (YN), are planning to perform surveys in the White Salmon River and its tributaries. The likely survey objectives will be to investigate the presence of lamprey, habitat conditions, and habitat availability. In preparation for this work, a compilation and review of the relevant aquatic habitat and biological information on the White Salmon River was conducted. References specific to the White Salmon River were collected and an annotated bibliography was produced including reports containing: •Spatial information about where various habitat surveys or monitoring have occurred over the past 20 years; •Database information relevant to habitat attributes (for example, pools, riffles, or glides); •Riparian surveys along major tributary streams; •Water temperature and sediment information; •Lamprey surveys, observations, and collections; •Spawning gravel surveys; and •Surveys that inventory habitat degradation or other environmental factors that may limit potential future productivity of lamprey.

Washington↗

USGS2006

Variation in thermal tolerance and routine metabolism among spring- and stream dwelling freshwater sculpins (Teleostei: Cottidae) of the southeastern United States

Evolutionary theory predicts that some aquatic organisms may adapt by directional selection to limiting physical environmental conditions, yet empirical data are conflicting. We sought to test the assumption that sculpins (family Cottidae) inhabiting thermally stable springs of the southeastern United States differ in temperature tolerance and metabolism from populations inhabiting more thermally labile stream habitats. Spring populations of pygmy sculpins ( Cottus pygmaeus ) and Ozark sculpins ( C. hypselurus ) differed interspecifically in thermal tolerance from populations of stream-dwelling mottled ( C. bairdi ) and Tallapoosa sculpins ( C. tallapoosae ), and both stream and spring populations of banded sculpins ( C. carolinae ). No intra- or interspecific differences in thermal tolerance were found among populations of C. bairdi, C. talla poosae , or C. carolinae . Cottus pygmaeus acclimated to 15°C differed intraspecifically in routine metabolism from fish acclimated to 20° and 25°C. Cottus pygmaeus and stream-dwelling C. bairdi and C. carolinae acclimated to temperatures of 20° and 25°C showed no interspecific differences in routine metabolism. Our results suggest that some spring-adapted populations or species may be more stenothermal than stream-dwelling congeners, but a greater understanding of the interactions of other physical and biological factors is required to better explain micro- and macro habitat distributions of eastern North American sculpins.

Ecology of Freshwater Fish↗

USGS2026

PFAS mixture composition and internal exposure profiles shape biological responses under field-realistic exposure

Per- and polyfluoroalkyl substances (PFAS) occur as complex mixtures, yet mixture-dependent biological effects under environmentally realistic exposure conditions remain poorly understood. We conducted multiyear (2018, 2019, 2021) continuous-flow, field-based exposures of male fathead minnows ( Pimephales promelas ) using a low-PFAS reference well (REF; sum of measured PFAS (∑PFAS) 0.1–0.2 μg L –1 ) and PFAS-contaminated groundwater from a fire-training area (FTA) at Joint Base Cape Cod, Massachusetts. Dilution treatments enabled separation of concentration and mixture effects. Groundwater from well FTA1 was perfluorooctanesulfonate (PFOS) dominated (∑PFAS 10–31 μg L –1 ), whereas groundwater from well FTA2 had higher concentrations and was enriched in perfluorooctanoate (PFOA) and diverse precursors (∑PFAS ∼ 80 μg L –1 ). Despite comparable plasma ∑PFAS and PFOS in FTA1–100% and FTA2–50% on day-7, cumulative mortality reached approximately 35% in FTA2–50% and 17% in FTA2–100%, and secondary sex trait expression was reduced by approximately 65–80% relative to REF, whereas sperm motility effects were mixture- and time-dependent. Plasma PFAS profiles were dominated by perfluorohexanesulfonate (PFHxS), PFOS, and sulfonamide precursors. Liver transcriptomics from REF-acclimated fish revealed robust disruption of metabolic, mitochondrial, and endocrine pathways that link PFAS mixture chemistry and internal exposure profiles to organismal outcomes, and testis transcriptomics provided complementary insight into reproductive impairment. These results indicate that PFAS mixture composition and internal exposure profiles, including precursor-associated differences, are important determinants of ecotoxicological outcomes under field-realistic conditions.

Massachusetts↗

USGS2022

Bright spots for inland fish and fisheries to guide future hydropower development

Hydropower production is one of the greatest threats to fluvial ecosystems and freshwater biodiversity. Now that we have entered the Anthropocene , there is an opportunity to reflect on what might constitute a ‘sustainable’ Anthropocene in the context of hydropower and riverine fish populations. Considering elements of existing practices that promote favorable social-ecological outcomes (i.e., ‘bright spots’) is timely given that there are plans to expand hydropower capacity in previously undammed rivers, intensify dam development in some of the world's largest river systems, and re-license existing facilities. We approach this from a pragmatic perspective: for the foreseeable future, hydropower will likely remain an important source of renewable electricity. To offer support for moving toward a more ‘sustainable’ Anthropocene, we provide syntheses of best practices during the siting, design, construction, operation, and compensation phases of hydropower development to minimize impacts on inland fish. For each phase, we offer positive examples (or what might be considered ‘bright spots’) pertaining to some of the approaches described within our syntheses, acknowledging that these projects may not be viewed as without ecological and (or) societal detriment by all stakeholders. Our findings underscore the importance of protecting critical habitat and free-flowing river reaches through careful site selection and basin-scale planning, infrastructure designs that minimize reservoir effects and facilitate safe passage of fish, construction of hydropower plants using best practices that minimize long-term damage, operating guidelines that mimic natural flow conditions, and compensation that is lasting, effective, inclusive, and locally relevant. Learning from these ‘bright spots’ may require engagement of diverse stakeholders, professionals, and governments at scales that extend well beyond a given site, river, or even basin. Indeed, environmental planning that integrates hydropower development into broader discussions of conserving regional biodiversity and ecosystem services will be of utmost importance.

Water Biology and Security↗

USGS2025

Streamflow as a stressor: Disentangling hydrology and water quality impacts to characterize flow-ecology relationships for two stream assemblages across two southeastern landscapes

Disassociating the independent effects of flow and water quality on the ecology of flowing waters is an overarching goal in water resource science needed to improve the efficacy of watershed management. However, the interrelatedness of these gradients and their subsequent alteration due to land use change has constrained progress made on this front. The objective of this study was to use benthic macroinvertebrate and fish assemblage data to characterize flow-ecology relationships that were unchanged by water quality impacts across two southeastern landscapes in the USA to help detect ecological change driven by flow alteration. General linear latent models were used to identify taxa that were responsive to high or low flow metrics and water quality gradients. Bayesian hierarchical generalized additive models were then developed using these indicator taxa and three biological metrics to identify flow-specific relationships that were unaffected by water quality impacts. Three low flow-specific relationships were identified, illustrating how potential agricultural or urban impacts to hydrology reduced stream biological health. Importantly, flow-ecology relationships developed using indicator taxa in this study effectively captured hydrology-specific impacts while biological metrics typical of state monitoring and assessment programs did not. Therefore, developing flow-specific biological metrics is a critical step when developing management strategies targeting flow alteration. Implementing standardized frameworks such as the one characterized here can limit contradictory findings and improve streamflow enhancement and restoration project efficacy. These low flow-specific relationships will enhance managers' capacity to develop environmental flow standards, monitor their success, and better understand urban and agricultural impacts on stream assemblages.

Alabama↗

USGS2022

Using biological responses to monitor freshwater post-spill conditions over 3 years in Blacktail Creek, North Dakota, USA

A pipeline carrying unconventional oil and gas (OG) wastewater spilled approximately 11 million liters of wastewater into Blacktail Creek, North Dakota, USA. Flow of the mix of stream water and wastewater down the channel resulted in storage of contaminants in the hyporheic zone and along the banks, providing a long-term source of wastewater constituents to the stream. A multi-level investigation was used to assess the potential effects of oil and brine spills on aquatic life. In this study, we used a combination of experiments using a native fish species, Fathead Minnow ( Pimephales promelas ), field sampling of the microbial community structure, and measures of estrogenicity. The fish investigation included in situ experiments and experiments with collected site water. Estrogenicity was measured in collected site water samples, and microbial community analyses were conducted on collected sediments. During the initial post-spill investigation, February 2015, performing in situ fish bioassays was impossible because of ice conditions. However, microbial community (e.g., the presence of members of the Halomonadaceae, a family that is indicative of elevated salinity) and estrogenicity differences were compared to reference sites and point to early biological effects of the spill. We noted water column effects on in situ fish survival 6 months post-spill during June 2015. At that time, total dissolved ammonium (sum of ammonium and ammonia, TAN) was 4.41 mg NH 4 /L with an associated NH 3 of 1.09 mg/L, a concentration greater than the water quality criteria established to protect aquatic life. Biological measurements in the sediment defined early and long-lasting effects of the spill on aquatic resources. The microbial community structure was affected during all sampling events. Therefore, sediment may act as a sink for constituents spilled and as such provide an indication of continued and cumulative effects post-spill. However, lack of later water column effects may reflect pulse hyporheic flow of ammonia from shallow ground water. Combining fish toxicological, microbial community structure and estrogenicity information provides a complete ecological investigation that defines potential influences of contaminants at organismal, population, and community levels. In general, in situ bioassays have implications for the individual survival and changes at the population level, microbial community structure defines potential changes at the community level, and estrogenicity measurements define changes at the individual and molecular level. By understanding effects at these various levels of biological organization, natural resource managers can interpret how a course of action, especially for remediation/restoration, might affect a larger group of organisms in the system. The current work also reviews potential effects of additional constituents defined during chemistry investigations on aquatic resources.

North Dakota↗

USGS2021

Reproductive health and endocrine disruption in smallmouth bass (Micropterus dolomieu) from the Lake Erie drainage, Pennsylvania, USA

Smallmouth bass Micropterus dolomieu were sampled from three sites within the Lake Erie drainage (Elk Creek, Twentymile Creek, and Misery Bay, an embayment in Presque Isle Bay). Plasma, tissues for histopathological analyses, and liver and testes preserved in RNALater® were sampled from 30 smallmouth bass (of both sexes) at each site. Liver and testes samples were analyzed for transcript abundance with Nanostring nCounter® technology. Evidence of estrogenic endocrine disruption was assessed by the presence and severity of intersex (testicular oocytes; TO) and concentrations of plasma vitellogenin in male fish. Abundance of 17 liver transcripts associated with reproductive function, endocrine activity, and contaminant detoxification pathways and 40 testes transcripts associated with male and female reproductive function, germ cell development, and steroid biosynthesis were also measured. Males with a high rate of TO (87–100%) and plasma vitellogenin were noted at all sites; however, TO severity was greatest at the site with the highest agricultural land cover. Numerous transcripts were differentially regulated among the sites and patterns of transcript abundance were used to better understand potential risk factors for estrogenic endocrine disruption. The results of this study suggest endocrine disruption is prevalent in this region and further research would benefit to identify the types of contaminants that may be associated with the observed biological effects.

Pennsylvania↗

USGS2014

Ecological and evolutionary patterns of freshwater maturation in Pacific and Atlantic salmonines

Reproductive tactics and migratory strategies in Pacific and Atlantic salmonines are inextricably linked through the effects of migration (or lack thereof) on age and size at maturity. In this review, we focus on the ecological and evolutionary patterns of freshwater maturation in salmonines, a key process resulting in the diversification of their life histories. We demonstrate that the energetics of maturation and reproduction provides a unifying theme for understanding both the proximate and ultimate causes of variation in reproductive schedules among species, populations, and the sexes. We use probabilistic maturation reaction norms to illustrate how variation in individual condition, in terms of body size, growth rate, and lipid storage, influences the timing of maturation. This useful framework integrates both genetic and environmental contributions to conditional strategies for maturation and, in doing so, demonstrates how flexible life histories can be both heritable and subject to strong environmental influences. We review evidence that the propensity for freshwater maturation in partially anadromous species is predictable across environmental gradients at geographic and local spatial scales. We note that growth is commonly associated with the propensity for freshwater maturation, but that life-history responses to changes in growth caused by temperature may be strikingly different than changes caused by differences in food availability. We conclude by exploring how contemporary management actions can constrain or promote the diversity of maturation phenotypes in Pacific and Atlantic salmonines and caution against underestimating the role of freshwater maturing forms in maintaining the resiliency of these iconic species.

Reviews in Fish Biology and Fisheries↗

USGS2014

Pesticide Toxicity Index: a tool for assessing potential toxicity of pesticide mixtures to freshwater aquatic organisms

Pesticide mixtures are common in streams with agricultural or urban influence in the watershed. The Pesticide Toxicity Index (PTI) is a screening tool to assess potential aquatic toxicity of complex pesticide mixtures by combining measures of pesticide exposure and acute toxicity in an additive toxic-unit model. The PTI is determined separately for fish, cladocerans, and benthic invertebrates. This study expands the number of pesticides and degradates included in previous editions of the PTI from 124 to 492 pesticides and degradates, and includes two types of PTI for use in different applications, depending on study objectives. The Median-PTI was calculated from median toxicity values for individual pesticides, so is robust to outliers and is appropriate for comparing relative potential toxicity among samples, sites, or pesticides. The Sensitive-PTI uses the 5th percentile of available toxicity values, so is a more sensitive screening-level indicator of potential toxicity. PTI predictions of toxicity in environmental samples were tested using data aggregated from published field studies that measured pesticide concentrations and toxicity to Ceriodaphnia dubia in ambient stream water. C. dubia survival was reduced to ≤ 50% of controls in 44% of samples with Median-PTI values of 0.1–1, and to 0% in 96% of samples with Median-PTI values > 1. The PTI is a relative, but quantitative, indicator of potential toxicity that can be used to evaluate relationships between pesticide exposure and biological condition.

Science of the Total Environment↗

USGS2018

Estimating freshwater productivity, overwinter survival, and migration patterns of Klamath River Coho Salmon

An area of great importance to resource management and conservation biology in the Klamath Basin is balancing water usage against the life history requirements of threatened Coho Salmon. One tool for addressing this topic is a freshwater dynamics model to forecast Coho Salmon productivity based on environmental inputs. Constructing such a forecasting tool requires local data to quantify the unique life history processes of Coho Salmon inhabiting this region. Here, we describe analytical methods for estimating a series of sub-models, each capturing a different life history process, which will eventually be synchronized as part of a freshwater dynamics model for Klamath River Coho Salmon. Specifically, we draw upon extensive population monitoring data collected in the basin to estimate models of freshwater productivity, overwinter survival, and migration patterns. Our models of freshwater productivity indicated that high summer temperatures and high winter flows can both adversely affect smolt production and that such relationships are more likely in tributaries with naturally regulated flows due to substantial intraannual environmental variation. Our models of overwinter survival demonstrated extensive variability in survival among years, but not among rearing locations, and demonstrated that a substantial proportion (~ 20%) of age-0+ fish emigrate from some rearing sites in the winter. Our models of migration patterns indicated that many age-0+ fish redistribute in the basin during the summer and winter. Further, we observed that these redistributions can entail long migrations in the mainstem where environmental stressors likely play a role in cueing refuge entry. Finally, our models of migration patterns indicated that changes in discharge are important in cueing the seaward migration of smolts, but that the nature of this behavioral response can differ dramatically between tributaries with naturally and artificially regulated flows. Collectively, these analyses demonstrate that environmental variation interacts with most phases of the freshwater life history of Klamath River Coho Salmon and that anthropogenic environmental variation can have a particularly large bearing on productivity.

Arcata Fisheries Technical Report↗

USGS2019

Flow modification in the Nation’s streams and rivers

This report summarizes a national assessment of flowing waters conducted by the U.S. Geological Survey’s (USGS) National Water-Quality Assessment (NAWQA) Project and addresses several pressing questions about the modification of natural flows in streams and rivers. The assessment is based on the integration, modeling, and synthesis of monitoring data collected by the USGS and the U.S. Environmental Protection Agency at more than 7,000 streams and rivers across the conterminous United States from 1980 to 2014. Key findings include the following. First, flow in many of the Nation’s streams and rivers is different from what it would be under natural conditions. In particular, low flows are more frequent, are of shorter duration, and vary less from one year to the next than they would naturally. In addition, high flows have been reduced in magnitude, are of shorter duration, are less frequent, and vary less from one year to the next than they would naturally. Other characteristics of natural flows also have been modified. Second, over the last 60 years (1955–2014), climatic trends have caused a change of 50 percent or more in one or more streamflow attributes at two-thirds of climate-sensitive streamgaging sites. However, these climate-induced changes have been less influential on streamflow modification than have land and water-management practices. Third, in every region assessed, streamflow modification was associated with reduced ecological health, as indicated by two biological communities—invertebrates and fish. Biological communities were increasingly likely to be impaired (defined as having lost a statistically significant number of species) in streams with flows most different from natural conditions. Finally, several case studies are presented that illustrate viable management strategies for balancing the water needs of people and ecosystems.

Circular↗

USGS2019

Environmental and biological factors influence migratory Sea Lamprey catchability: Implications for tracking abundance in the Laurentian Great Lakes

Sea Lamprey Petromyzon marinus population trends in the Great Lakes are tracked by trapping migratory adults in tributaries and using mark and recapture techniques to estimate abundance. Understanding what environmental and biological factors influence Sea Lamprey capture in tributaries is crucial to developing efficient trapping methods and reliable abundance estimates. We analyzed data from trapping sites located on eight Great Lakes tributaries using Cormack-Jolly-Seber models and examined how water temperature, discharge, sex, and length influenced Sea Lamprey apparent survival and capture probability. Sea Lamprey apparent survival was negatively associated with water temperature in all tributaries. Additionally, the odds of small Sea Lamprey (≤45 cm) remaining available to capture were 39% less (95% CI: 63% decrease – 1% increase) than large (>45 cm) lamprey odds. These observed relationships were used to investigate if bias in abundance estimates using the pooled-Petersen estimator and Jolly-Seber models was expected to be similar across trapping locations or influenced by variable environmental conditions and biological traits. Pooled-Petersen abundance estimates had a positive bias when datasets were generated from simulated populations with empirical relationships between environmental characteristics and catchability. The degree of bias depended upon changes in stream warming patterns and was not consistent among trapping locations. Jolly-Seber models using data from either weekly-batch-marked or uniquely-marked individuals generated abundance estimate with low bias when data quality was high, but performed poorly in scenarios with few recaptured Sea Lamprey. This research can promote improved Sea Lamprey monitoring efforts by providing insight into the reliability of the pooled-Petersen abundance estimator as a tool for tracking Sea Lamprey populations and demonstrating the limitations of adopting more robust methods when data are sparse.

Laurentian Great lakes↗

USGS2005

Bioeconomic analysis of selected conservation practices on soil erosion and freshwater fisheries

Farmers can generate environmental benefits (improved water quality and fisheries and wildlife habitat), but they may not be able to quantify them. Furthermore, farmers may reduce their incomes from managing lands to produce these positive externalities but receive little monetary compensation in return. This study simulated the relationship between agricultural practices, water quality, fish responses to suspended sediment and farm income within two small watersheds, one of a cool water stream and one of a warm water stream. Using the Agricultural Drainage and Pesticide Transport (ADAPT) model, this study related best management practices (BMPs) to calculated instream suspended sediment concentrations by estimating sediment delivery, runoff, base flow, and streambank erosion to quantify the effects of suspended sediment exposure on fish communities. By implementing selected BMPs in each watershed, annual net farm income declined $18,000 to $28,000 (1 to 3 percent) from previous levels. “Lethal” fish events from suspended sediments in the cool water watershed decreased by 60 percent as conservation tillage and riparian buffers increased. Despite reducing suspended sediments by 25 percent, BMPs in the warm water watershed did not reduce the negative response of the fisheries. Differences in responses (physical and biological) between watersheds highlight potential gains in economic efficiency by targeting BMPs or by offering performance based “green payments.”

Journal of the American Water Resources Associatio↗

USGS2007

Water-quality, sediment-quality, stream-habitat, and biological data for Mustang Bayou near Houston, Texas, 2004-05

The U.S. Geological Survey, in cooperation with the Houston-Galveston Area Council and the Texas Commission on Environmental Quality, collected water-quality, stream-habitat, and biological data from six sites (downstream order M6-M1) primarily in Brazoria County southeast of Houston, Texas, during September 2004-August 2005 and collected bed sediment data from one site in September 2005. Water-quality data collection consisted of continuously monitored (for periods of 24 hours to several days, six times) water temperature, pH, specific conductance, and dissolved oxygen and periodically collected samples of several properties and constituents. Monitored dissolved oxygen measurements were below minimum and 24-hour criteria at all sites except M2. Nitrogen compounds, phosphorus, biochemical oxygen demand, chlorophyll-a, E. coli, chloride, sulfate, solids, suspended sediment concentration, and pesticides were assessed at all sites. Concentrations of nitrogen compounds and phosphorus did not exceed Texas State screening levels. Biochemical oxygen demand was less than 4.0 milligrams per liter at all sites except M6, where the maximum concentration was 8.1 milligrams per liter. Concentrations of chlorophyll-a were less than the State screening level at all sites except M6, where four of eight samples equaled or exceeded the screening level. Twenty of 48 samples from Mustang Bayou had E. coli densities that exceeded the State single-sample water-quality standard. Median chloride concentrations from each site were between 42.2 and 123 milligrams per liter. Fifteen pesticide compounds (six herbicides and nine insecticides) were detected in 24 water samples. The most frequently detected pesticide was atrazine, which was found in every sample. Other frequently detected pesticides were 2-chloro-4-isopropylamino-6-amino-s-triazine (CIAT), prometon, tebuthiuron, fipronil, and the pesticide degradates, fipronil sulfide and fipronil sulfone. Sediment samples were collected from the stream bottom at M1 and analyzed for concentrations of trace elements (metals), polycyclic aromatic hydrocarbons, organochlorine pesticides, and polychlorinated biphenyls. No organochlorine pesticides or polychlorinated biphenyls were detected. No concentrations of metals exceeded State screening levels. Measurable concentrations of 11 polycyclic aromatic hydrocarbon (PAH) compounds were detected, and three other PAH compounds were detected but not quantified by the laboratory. Stream habitat and aquatic biota (benthic macroinvertebrates and fish) were surveyed at each site three times during the study to evaluate aquatic life use. Characteristics of habitat measured during each survey were scored using a habitat quality index. Average aquatic-life-use scores were 'limited' for M3-M6 and 'intermediate' for M1 and M2. A total of 2,557 macroinvertebrate individuals were identified from Mustang Bayou. Benthic macroinvertebrate assemblages were scored using indexes specified by the Texas Commission on Environmental Quality. Average aquatic-life-use scores were 'limited' at M1, 'intermediate' at M3-M6, and 'high' at M2. Forty-six species of fish representing 20 families were collected from Mustang Bayou. A total of 4,115 fish were collected. Sunfish (Centrarchidae) was the most abundant family, accounting for about 28 percent. Aquatic-life-use scores at sites in Mustang Bayou were determined using the regional index of biotic integrity for ecoregion 34 and were 'high' for all sites.

Data Series↗

USGS2014

Assessment of metal and trace element contamination in water, sediment, plants, macroinvertebrates, and fish in Tavasci Marsh, Tuzigoot National Monument, Arizona

Tavasci Marsh is a large freshwater marsh within the Tuzigoot National Monument in central Arizona. It is the largest freshwater marsh in Arizona that is unconnected to the Colorado River and is designated as an Important Bird Area by the Audubon Society. The marsh has been altered significantly by previous land use and the monument’s managers are evaluating the restoration of the marsh. In light of historical mining activities located near the marsh from the first half of the 20th century, evaluations of water, sediment, plant, and aquatic biota in the marsh were conducted. The evaluations were focused on nine metals and trace elements commonly associated with mining and other anthropogenic activities (As, Cd, Cr, Cu, Hg, Ni, Pb, Se, and Zn) together with isotopic analyses to understand the presence, sources and timing of water and sediment contaminants to the marsh and the occurrence in aquatic plants, dragonfly larvae, and fish. Results of water analyses indicate that there were two distinct sources of water contributing to the marsh during the study: one from older high elevation recharge entering the marsh at Shea Spring (as well as a number of unnamed seeps and springs on the northeastern edge of the marsh) and the other from younger low elevation recharge or from Pecks Lake. Water concentrations for arsenic exceeded the U.S. Environmental Protection Agency primary drinking water standard of 10 μg/L at all sampling sites. Surface waters at Tavasci Marsh may contain conditions favorable for methylmercury production. All surficial and core sediment samples exceeded or were within sample concentration variability of at least one threshold sediment quality guideline for As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn. Several sediment sites were also above or were within sample concentration variability of severe or probable effect sediment quality guidelines for As, Cd, and Cu. Three sediment cores collected in the marsh have greater metal and trace element concentrations at depth for Bi, Cd, Cu, Hg, In, Pb, Sb, Sn, Te, and Zn. Radioisotope dating indicates that the elevated metal and trace element concentrations are associated with sediments deposited before 1963. Arsenic concentration was greater in cattail roots compared with surrounding sediment at Tavasci Marsh. Concentrations of As, Ni, and Se from yellow bullhead catfish (Ameiurus natalis) in Tavasci Marsh exceeded the 75th percentile of several other regional studies. Mercury concentration in dragonfly larvae and fish from Tavasci Marsh were similar to or greater than in Tavasci Marsh sediment. Future work includes a biologic risk assessment utilizing the data collected in this study to provide the monument management with additional information for their restoration plan.

Arizona↗

USGS2006

Impacts of new highways and subsequent landscape urbanization on stream habitat and biota

New highways are pervasive, pernicious threats to stream ecosystems because of their short- and long-term physical, chemical, and biological impacts. Unfortunately, standard environmental impact statements (EISs) and environmental assessments (EAs) focus narrowly on the initial direct impacts of construction and ignore other long-term indirect impacts. More thorough consideration of highway impacts, and, ultimately, better land use decisions may be facilitated by conceptualizing highway development in three stages: initial highway construction, highway presence, and eventual landscape urbanization. Highway construction is characterized by localized physical disturbances, which generally subside through time. In contrast, highway presence and landscape urbanization are characterized by physical and chemical impacts that are temporally persistent. Although the impacts of highway presence and landscape urbanization are of similar natures, the impacts are of a greater magnitude and more widespread in the urbanization phase. Our review reveals that the landscape urbanization stage is clearly the greatest threat to stream habitat and biota, as stream ecosystems are sensitive to even low levels (<10%) of watershed urban development. Although highway construction is ongoing, pervasive, and has severe biological consequences, we found few published investigations of its impacts on streams. Researchers know little about the occurrence, loading rates, and biotic responses to specific contaminants in highway runoff. Also needed is a detailed understanding of how highway crossings, especially culverts, affect fish populations via constraints on movement and how highway networks alter natural regimes (e.g., streamflow, temperature). Urbanization research topics that may yield especially useful results include a) the relative importance and biological effects of specific components of urban development - e.g., commercial or residential; b) the scenarios under which impacts are reversible; and c) the efficacy of mitigation measures - e.g., stormwater retention or treatment and forested buffers. Copyright ?? Taylor & Francis Inc.

Reviews in Fisheries Science↗