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At least 1,351 records · Page 75Linked to original sources
USGS2022

Stable isotopes provide insight into sources and cycling of N compounds in the Sacramento-San Joaquin Delta, California, USA

River deltas and their diverse array of aquatic environments are increasingly impacted by anthropogenic inputs of nitrogen (N). These inputs can alter the N biogeochemistry of these systems and promote undesirable phenomena including harmful algae blooms and invasive aquatic macrophytes. To examine N sources and biogeochemical processes in the Sacramento-San Joaquin Delta, a river delta located in central California, USA, that is fed primarily by the Sacramento River, we utilized a multi-tracer approach that measured N species concentrations and stable isotope values monthly from April 2011 to November 2012 in samples collected from the channelized mainstem of the Sacramento River, two channelized distributaries of the Sacramento River, and the Cache Slough Complex, a network of Sacramento River tributaries and shallow water wetland habitat. We found that the Sacramento River and its channelized distributaries received N primarily in the form of NH 4 + from treated wastewater effluent and that NH 4 + was lost rapidly while NO 3 − was gained more slowly during subsequent downstream transit, driven by an array of biogeochemical processes whose identities could be constrained via examination of stable isotope values. The Cache Slough Complex, which was characterized by lower net flows and higher water residence times than the Sacramento River and its distributaries, received variable inputs of low conductivity water elevated in NH 4 + from the Sacramento River and higher conductivity water elevated in NO 3 − from landward tributaries. Deviations from expected conservative mixing of these sources were spatially variable but broadly indicative of local inputs of treated wastewater effluent NO 3 − , conversion of Sacramento River NH 4 + to NO 3 − via nitrification, uptake of NH 4 + and NO 3 − by phytoplankton, and remineralization of organic N. These findings highlight both the diversity in N dynamics in anthropogenically impacted river delta environments and the utility of a multi-tracer approach in constraining these processes in such complex systems.

California↗
USGS2013

Geomorphic and vegetation processes of the Willamette River floodplain, Oregon: current understanding and unanswered science questions

This report summarizes the current understanding of floodplain processes and landforms for the Willamette River and its major tributaries. The area of focus encompasses the main stem Willamette River above Newberg and the portions of the Coast Fork Willamette, Middle Fork Willamette, McKenzie, and North, South and main stem Santiam Rivers downstream of U.S. Army Corps of Engineers dams. These reaches constitute a large portion of the alluvial, salmon-bearing rivers in the Willamette Basin. The geomorphic, or historical, floodplain of these rivers has two zones - the active channel where coarse sediment is mobilized and transported during annual flooding and overbank areas where fine sediment is deposited during higher magnitude floods. Historically, characteristics of the rivers and geomorphic floodplain (including longitudinal patterns in channel complexity and the abundance of side channels, islands and gravel bars) were controlled by the interactions between floods and the transport of coarse sediment and large wood. Local channel responses to these interactions were then shaped by geologic features like bedrock outcrops and variations in channel slope. Over the last 150 years, floods and the transport of coarse sediment and large wood have been substantially reduced in the basin. With dam regulation, nearly all peak flows are now confined to the main channels. Large floods (greater than 10-year recurrence interval prior to basinwide flow regulation) have been largely eliminated. Also, the magnitude and frequency of small floods (events that formerly recurred every 2–10 years) have decreased substantially. The large dams trap an estimated 50–60 percent of bed-material sediment—the building block of active channel habitats—that historically entered the Willamette River. They also trap more than 80 percent of the estimated bed material in the lower South Santiam River and Middle and Coast Forks of the Willamette River. Downstream, revetments further decrease bed-material supply by an unknown amount because they limit bank erosion and entrainment of stored sediment. The rivers, geomorphic floodplain, and vegetation within the study area have changed noticeably in response to the alterations in floods and coarse sediment and wood transport. Widespread decreases have occurred in the rates of meander migration and avulsions and the number and diversity of landforms such as gravel bars, islands, and side channels. Dynamic and, in some cases, multi-thread river segments have become stable, single-thread channels. Preliminary observations suggest that forest area has increased within the active channel, further reducing the area of unvegetated gravel bars. Alterations to floods and sediment transport and ongoing channel, floodplain, and vegetation responses result in a modern Willamette River Basin. Here, the floodplain influenced by the modern flow and sediment regimes, or the functional floodplain, is narrower and inset with the broader and older geomorphic floodplain. The functional floodplain is flanked by higher elevation relict floodplain features that are no longer inundated by modern floods. The corridor of present- day active channel surfaces is narrower, enabling riparian vegetation to establish on formerly active gravel bar surfaces. The modern Willamette River Basin with its fundamental changes in the flood, sediment transport, and large wood regimes has implications for future habitat conditions. System-wide future trends probably include narrower floodplains and a lower diversity of landforms and habitats along the Willamette River and its major tributaries compared to historical patterns and today. Furthermore, specific conditions and future trends will probably vary between geologically stable, anthropogenically stable, and dynamic reaches. The middle and lower segments of the Willamette River are geologically stable, whereas the South Santiam and Middle Fork Willamette Rivers were historically dynamic, but are now largely stable in response to flow regulation and revetment construction. The upper Willamette and North Santiam Rivers retain some dynamic characteristics, and provide the greatest diversity of aquatic and riparian habitats under the current flow and sediment regime. The McKenzie River has some areas that are more dynamic, whereas other sections are stable due to geology or revetments. Historical reductions in channel dynamism also have implications for ongoing and future recruitment and succession of floodplain forests. For instance, the succession of native plants like black cottonwood is currently limited by (1) fewer low-elevation gravel bars for stand initiation; (2) altered streamflow during seed release, germination, and stand initiation; (3) competition from introduced plant species; and (4) frequent erosion of young vegetation in some locations because scouring flows are concentrated within a narrow channel corridor. Despite past alterations, the Willamette River Basin has many of the physical and ecological building blocks necessary for highly functioning rivers. Management strategies, including environmental flow programs, river and floodplain restoration, revetment modifications, and reclamation of gravel mines, are underway to mitigate some historical changes. However, there are some substantial gaps in the scientific understanding of the modern Willamette basin that is needed to efficiently integrate these blocks and to establish realistic objectives for future conditions. Unanswered questions include: 1. What is the distribution and diversity of landforms and habitats along the Willamette River and its tributaries? 2. What is the extent of today’s functional floodplain—the part of the river corridor actively formed and modified by fluvial processes? 3. How are landforms and habitats in the Willamette River Basin created and sustained by present-day flow and sediment conditions? 4. How is the succession of native floodplain vegetation shaped by present-day flow and sediment conditions? Answering these questions will produce baseline data on the current distributions of landforms and habitats (question 1), the extent of the functional floodplain (question 2), and the effects of modern flow and sediment regimes on future floodplain landforms, habitats, and vegetation succession (questions 3 and 4). Addressing questions 1 and 2 is a logical next step because they underlie questions 3 and 4. Addressing these four questions would better characterize the modern Willamette Basin and help in implementing and setting realistic targets for ongoing management strategies, demonstrating their effectiveness at the site and basin scales, and anticipating future trends and conditions.

Oregon↗
USGS2014

Contaminants of legacy and emerging concern in largescale suckers (Catostomus macrocheilus) and the foodweb in the lower Columbia River, Oregon and Washington, USA

We investigated occurrence, transport pathways, and effects of polybrominated diphenyl ether (PBDE) flame retardants and other endocrine disrupting chemicals (EDCs) in aquatic media and the foodweb in the lower Columbia River. In 2009 and 2010, foodweb sampling at three sites along a gradient of contaminant exposure near Skamania (Washington), Columbia City (Oregon) and Longview (Washington) included water (via passive samplers), bed sediment, invertebrate biomass residing in sediment, a resident fish species (largescale suckers [ Catostomus macrocheilus ]), and eggs from osprey ( Pandion haliaetus ). This paper primarily reports fish tissue concentrations. In 2009, composites of fish brain, fillet, liver, stomach, and gonad tissues revealed that overall contaminant concentrations were highest in livers, followed by brain, stomach, gonad, and fillet. Concentrations of halogenated compounds in tissue samples from all three sites ranged from < 1 to 400 nanograms per gram of wet tissue. Several chemical classes, including PBDEs, organochlorine pesticides, and polychlorinated biphenyls (PCBs), were detected at all sites and in nearly all fish tissues sampled. In 2010, only fish livers were sampled and inter-site concentration differences were not as pronounced as in 2009. Chemical concentrations in sediments, fish tissues, and osprey eggs increased moving downstream from Skamania to the urbanized sites near Columbia City and Longview. Numerous organochlorine (OC) pesticides, both banned and currently used, and PBDEs, were present at each site in multiple media and concentrations exceeded environmental quality benchmarks in some cases. Frequently detected OC compounds included hexachlorobenzene, pentachloroanisole, dichlorodiphenyltrichloroethane (DDT) and its degradates, chlorpyrifos, and oxyfluorofen. Biomagnification of BDE47, 100, 153, and 154 occurred in largescale suckers and osprey eggs. Results support the hypothesis that contaminants in the environment lead to bioaccumulation and potential negative effects in multiple levels of the foodweb.

Oregon, Washington↗
USGS2024

An evaluation of tradeoffs in restoring ephemeral vs. perennial habitats to conserve animal populations

Introduction: Habitat loss and degradation pose significant threats to global fish and wildlife populations, prompting substantial investments in habitat creation and restoration efforts. Not all habitats provide equal benefits, leading to challenges in prioritizing restoration actions. For example, juvenile anadromous salmonids require high quality rearing aquatic habitats to achieve the physiological requirements needed to successfully migrate to the ocean. However, there are profound disagreements among anadromous salmon restoration managers whether it is best to focus efforts on restoring in-channel habitats that are available for the entire rearing period or floodplain habitats that, while facilitating greater growth and survival than in-channel habitats, are only available for a few weeks at a time and are typically only activated every two-to-three years. Methods: We used an existing fall-run Chinook salmon decision-support model to evaluate under what conditions floodplain restoration would provide greater benefits than in-channel habitat restoration. The simulations included a wide range of floodplain inundation frequencies and durations and floodplain benefits in the form of increased survival and growth relative to in-channel habitats. Results: The simulations results indicated that in-channel habitat restoration was always the best habitat restoration action when there was no existing in-channel habitat despite simulating a wide range of flood frequency, duration, and growth and survival benefits. Floodplain restoration was generally best when there was sufficient in-channel habitat available to successfully rear most of the juveniles produced by the returning adult salmon. Discussion: We hypothesize that in-channel and floodplain habitats have different roles in salmon population maintenance with in-channel habitats regulating the overall population size and floodplains acting as recurrent resource pulses. Our study provides a quantitative framework to evaluate the benefit of these two habitat types and provides generalizable rulesets that can be used by managers when implementing habitat restoration strategies for species that inhabit both in-channel and floodplain habitats.

California↗
USGS2023

Broad-scale assessment of methylmercury in adult amphibians

Mercury (Hg) is a toxic contaminant that has been mobilized and distributed worldwide and is a threat to many wildlife species. Amphibians are facing unprecedented global declines due to many threats including contaminants. While the biphasic life history of many amphibians creates a potential nexus for methylmercury (MeHg) exposure in aquatic habitats and subsequent health effects, the broad-scale distribution of MeHg exposure in amphibians remains unknown. We used nonlethal sampling to assess MeHg bioaccumulation in 3,241 juvenile and adult amphibians during 2017–2021. We sampled 26 populations (14 species) across 11 states in the United States, including several imperiled species that could not have been sampled by traditional lethal methods. We examined whether life history traits of species and whether the concentration of total mercury in sediment or dragonflies could be used as indicators of MeHg bioaccumulation in amphibians. Methylmercury contamination was widespread, with a 33-fold difference in concentrations across sites. Variation among years and clustered subsites was less than variation across sites. Life history characteristics such as size, sex, and whether the amphibian was a frog, toad, newt, or other salamander were the factors most strongly associated with bioaccumulation. Total Hg in dragonflies was a reliable indicator of bioaccumulation of MeHg in amphibians (R 2 ≥ 0.67), whereas total Hg in sediment was not (R 2 ≤ 0.04). Our study, the largest broad-scale assessment of MeHg bioaccumulation in amphibians, highlights methodological advances that allow for nonlethal sampling of rare species and reveals immense variation among species, life histories, and sites. Our findings can help identify sensitive populations and provide environmentally relevant concentrations for future studies to better quantify the potential threats of MeHg to amphibians.

Environmental Science and Technology↗
USGS2016

Pan-arctic trends in terrestrial dissolved organic matter from optical measurements

Climate change is causing extensive warming across Arctic regions resulting in permafrost degradation, alterations to regional hydrology and shifting amounts and composition of dissolved organic matter (DOM) transported by streams and rivers. Here, we characterize the DOM composition and optical properties of the six largest Arctic rivers draining into the Arctic Ocean to examine the ability of optical measurements to provide meaningful insights into terrigenous carbon export patterns and biogeochemical cycling. The chemical composition of aquatic DOM varied with season, spring months were typified by highest lignin phenol and dissolved organic carbon (DOC) concentrations with greater hydrophobic acid content, and lower proportions of hydrophilic compounds, relative to summer and winter months. Chromophoric DOM (CDOM) spectral slope ( S 275–295 ) tracked seasonal shifts in DOM composition across river basins. Fluorescence and parallel factor analysis identified seven components across the six Arctic rivers. The ratios of “terrestrial humic-like” vs. “marine humic-like” fluorescent components co-varied with lignin monomer ratios over summer and winter months, suggesting fluorescence may provide information on the age and degradation state of riverine DOM. CDOM absorbance ( a 350 ) proved a sensitive proxy for lignin phenol concentrations across all six river basins and over the hydrograph, enabling for the first time the development of a single pan-arctic relationship between a 350 and terrigenous DOC ( R 2 = 0.93). Combining this lignin proxy with high-resolution monitoring of a 350 , pan-arctic estimates of annual lignin flux were calculated to range from 156 to 185 Gg, resulting in shorter and more constrained estimates of terrigenous DOM residence times in the Arctic Ocean (spanning 7 months to 2½ years). Furthermore, multiple linear regression models incorporating both absorbance and fluorescence variables proved capable of explaining much of the variability in lignin composition across rivers and seasons. Our findings suggest that synoptic, high-resolution optical measurements can provide improved understanding of northern high-latitude organic matter cycling and flux, and prove an important technique for capturing future climate-driven changes.

Frontiers in Earth Science↗
USGS2016

Controls on selenium distribution and mobilization in an irrigated shallow groundwater system underlain by Mancos Shale, Uncompahgre River Basin, Colorado, USA

Elevated selenium (Se) concentrations in surface water and groundwater have become a concern in areas of the Western United States due to the deleterious effects of Se on aquatic ecosystems. Elevated Se concentrations are most prevalent in irrigated alluvial valleys underlain by Se-bearing marine shales where Se can be leached from geologic materials into the shallow groundwater and surface water systems. This study presents groundwater chemistry and solid-phase geochemical data from the Uncompahgre River Basin in Western Colorado, an irrigated alluvial landscape underlain by Se-rich Cretaceous marine shale. We analyzed Se species, major and trace elements, and stable nitrogen and oxygen isotopes of nitrate in groundwater and aquifer sediments to examine processes governing selenium release and transport in the shallow groundwater system. Groundwater Se concentrations ranged from below detection limit (< 0.5 μg L − 1 ) to 4070 μg L − 1 , and primarily are controlled by high groundwater nitrate concentrations that maintain oxidizing conditions in the aquifer despite low dissolved oxygen concentrations. High nitrate concentrations in non-irrigated soils and nitrate isotopes indicate nitrate is largely derived from natural sources in the Mancos Shale and alluvial material. Thus, in contrast to areas that receive substantial NO 3 inputs through inorganic fertilizer application, Se mitigation efforts that involve limiting NO 3 application might have little impact on groundwater Se concentrations in the study area. Soluble salts are the primary source of Se to the groundwater system in the study area at-present, but they constitute a small percentage of the total Se content of core material. Sequential extraction results indicate insoluble Se is likely composed of reduced Se in recalcitrant organic matter or discrete selenide phases. Oxidation of reduced Se species that constitute the majority of the Se pool in the study area could be a potential source of Se in the future as soluble salts are progressively depleted.

Colorado↗
USGS2024

Fish beta diversity associated with hydrologic and anthropogenic disturbance gradients in contrasting stream flow regimes

Understanding the role of hydrologic variation in structuring aquatic communities is crucial for successful conservation and sustainable management of native freshwater biodiversity. Partitioning beta diversity into the additive components of spatial turnover and nestedness can provide insight into the forces driving variability in fish assemblages across stream flow regimes. We examined stream fish beta diversity across hydrologic and anthropogenic disturbance gradients using long-term (1916–2016) site occurrence records ( n = 17,375) encompassing 252 species. We assessed total beta diversity (Sørensen dissimilarity), spatial turnover, and nestedness of fish assemblages in contrasting stream flow regimes across a gradient of decreasing flow stability: groundwater stable ( n = 77), groundwater ( n = 67), groundwater flashy ( n = 175), perennial runoff ( n = 141), runoff flashy ( n = 255), and intermittent ( n = 63) streams. Differences in total beta diversity among the stream flow regimes were driven predominantly (>86 %) by spatial turnover (i.e. species replacement) as opposed to nestedness (i.e. species loss or gain). Total fish beta diversity and spatial turnover were highest in streams with intermediate flow stability (groundwater flashy), while more flow-stable streams (groundwater stable and groundwater) had lower turnover and higher nestedness. Species turnover was also strongly associated with seasonal variation in hydrology across all flow regimes, but these relationships were most evident for assemblages in intermittent streams. Distance-based statistical comparisons showed significant correlations between beta diversity and anthropogenic disturbance variables, including dam density, dam storage volume and water withdrawals in catchments of groundwater stable streams, while hydrologic variables were more strongly correlated with beta diversity in streams with runoff-dominated and flashy flow regimes. The high spatial turnover of species implies that fish conservation actions would benefit from watershed-focused approaches targeting multiple streams with wide spatial distribution, as opposed to simply focusing on preserving sites with the greatest number of species.

Science of the Total Envionrment↗
USGS2016

Using continuous underway isotope measurements to map water residence time in hydrodynamically complex tidal environments

Stable isotopes present in water (δ 2 H, δ 18 O) have been used extensively to evaluate hydrological processes on the basis of parameters such as evaporation, precipitation, mixing, and residence time. In estuarine aquatic habitats, residence time (τ) is a major driver of biogeochemical processes, affecting trophic subsidies and conditions in fish-spawning habitats. But τ is highly variable in estuaries, owing to constant changes in river inflows, tides, wind, and water height, all of which combine to affect τ in unpredictable ways. It recently became feasible to measure δ 2 H and δ 18 O continuously, at a high sampling frequency (1 Hz), using diffusion sample introduction into a cavity ring-down spectrometer. To better understand the relationship of τ to biogeochemical processes in a dynamic estuarine system, we continuously measured δ 2 H and δ 18 O, nitrate and water quality parameters, on board a small, high-speed boat (5 to >10 m s –1 ) fitted with a hull-mounted underwater intake. We then calculated τ as is classically done using the isotopic signals of evaporation. The result was high-resolution (∼10 m) maps of residence time, nitrate, and other parameters that showed strong spatial gradients corresponding to geomorphic attributes of the different channels in the area. The mean measured value of τ was 30.5 d, with a range of 0–50 d. We used the measured spatial gradients in both τ and nitrate to calculate whole-ecosystem uptake rates, and the values ranged from 0.006 to 0.039 d –1 . The capability to measure residence time over single tidal cycles in estuaries will be useful for evaluating and further understanding drivers of phytoplankton abundance, resolving differences attributable to mixing and water sources, explicitly calculating biogeochemical rates, and exploring the complex linkages among time-dependent biogeochemical processes in hydrodynamically complex environments such as estuaries.

California↗
USGS2019

Point sources and agricultural practices control spatial-temporal patterns of orthophosphate in tributaries to Chesapeake Bay

Orthophosphate (PO 4 ) is the most bioavailable form of phosphorus (P). Excess PO 4 may cause harmful algal blooms in aquatic ecosystems. A major restoration effort is underway for Chesapeake Bay (CB) to reduce P, nitrogen, and sediment loading to CB. Although PO 4 cycling and delivery to streams has been characterized in small-scale studies, regional drivers of PO 4 patterns remain poorly understood because most water quality trend assessment focus on total P. Moreover, these trend assessments are usually at an annual timestep. To address this research gap, we analyzed PO 4 patterns over a 9-year period at 53 monitoring stations across the CB watershed to: 1) characterize the role of PO 4 in total P fluxes and trends; 2) describe spatial and temporal patterns of PO 4 concentrations across seasons and streamflow ; and 3) explore factors explaining these patterns. Agricultural watersheds exported the most total P compared with watersheds under different land uses (e.g., urban or forest), with PO 4 comprising up to 50% of those exports. Although PO 4 exports are declining at many sites, some agricultural regions are experiencing increasing trends at a rate sufficient to drive total P trends. Regression modeling results suggest that point source load reductions are likely responsible for decreasing PO 4 concentrations observed at many sites. Watersheds with more Conservation Reserve Program enrollment had lower summer PO 4 concentrations, highlighting the effectiveness of this practice. Manure inputs strongly predicted PO 4 concentrations at high flows across all seasons. Both manure applications and conservation tillage were correlated with changes in PO 4 concentrations at high flow, suggesting these activities could contribute to increasing PO 4 concentrations. This study highlights the effectiveness of point source control for reducing PO 4 exports and underscores the need for management strategies to target sources, practices, and landscape factors determining PO 4 loss from soils where manure inputs remain high.

Delaware, Maryland, New York, Pennsylvania, Virgin↗
USGS2022

Pharmaceutical pollution of the world’s rivers

Environmental exposure to active pharmaceutical ingredients (APIs) can have negative effects on the health of ecosystems and humans. While numerous studies have monitored APIs in rivers, these employ different analytical methods, measure different APIs, and have ignored many of the countries of the world. This makes it difficult to quantify the scale of the problem from a global perspective. Furthermore, comparison of the existing data, generated for different studies/regions/continents, is challenging due to the vast differences between the analytical methodologies employed. Here, we present a global-scale study of API pollution in 258 of the world’s rivers, representing the environmental influence of 471.4 million people across 137 geographic regions. Samples were obtained from 1,052 locations in 104 countries (representing all continents and 36 countries not previously studied for API contamination) and analyzed for 61 APIs. Highest cumulative API concentrations were observed in sub-Saharan Africa, south Asia, and South America. The most contaminated sites were in low- to middle-income countries and were associated with areas with poor wastewater and waste management infrastructure and pharmaceutical manufacturing. The most frequently detected APIs were carbamazepine, metformin, and caffeine (a compound also arising from lifestyle use), which were detected at over half of the sites monitored. Concentrations of at least one API at 25.7% of the sampling sites were greater than concentrations considered safe for aquatic organisms, or which are of concern in terms of selection for antimicrobial resistance. Therefore, pharmaceutical pollution poses a global threat to environmental and human health, as well as to delivery of the United Nations Sustainable Development Goals.

Proceedings of the National Academy of Sciences↗
USGS2019

Methane and nitrous oxide temporal and spatial variability in two midwestern USA streams containing high nitrate concentrations

Concentrations and emissions of greenhouse gases CO 2 , CH 4 , and N 2 O commonly are examined individually in aquatic environments in which each is expected to be relatively important; however, their co-occurrence and dynamic interactions in fluvial settings could provide important information about their controlling biogeochemical processes and potential contributions to global climate change. Spatial and temporal variability of CH 4 , N 2 O, and CO 2 concentrations were measured from June 1999 to September 2003 in two nitrate-rich (40–1200 μM) streams draining agricultural land in the midwestern USA that differed ~13-fold in flow. Seasonal (biweekly), diel (hourly), and transport-oriented (reach-scale) sampling approaches were compared. Dissolved gas concentrations exceeded atmospheric equilibrium values up to 700- and 16-fold, for CH 4 and N 2 O, respectively. Mean concentrations were higher in the larger stream than in the smaller stream. In both streams, CH 4 emissions were generally higher in summer-fall and negatively correlated with flow and NO 3 − concentration while N 2 O emissions were generally higher in winter/spring and positively correlated with flow and NO 3 − . In the small stream, diel variations in the concentrations, emissions, and isotopic compositions of CH 4 , N 2 O, and NO 2 − resulted from diel variations in sources, sinks, and air-water gas exchange velocities. Seasonal mean total (CH 4 + N 2 O) area-normalized emission rates, expressed as CO 2 warming potential equivalents, were similar for the two streams, but the total reach-scale emission rate for the larger stream, including CO 2 , was about 2.9 times that of the smaller stream (131.6 vs 46.0 kg CO 2 equivalents km −1 day −1 , respectively). The CH 4 contribution to this flux was 9–28%, despite the relatively high NO 3 − and O 2 concentrations in the streams, indicating contributions from upwelling groundwater or reactions in streambed sediment.

Illinois, Indiana↗
USGS2020

Evaluation of EPT macroinvertebrate metrics in small streams located within the non-connected stormwater management region of Kansas City, Missouri, USA

During 2012-2014, we evaluated macroinvertebrate communities in streams draining the non-connected stormwater management region (Municipal Separate Storm Sewer System, or MS4) within the Kansas City metropolitan area utilizing the Missouri bioassessment protocols. Trends in aquatic life impairment status based on Missouri's Macroinvertebrate Stream Condition Index (MSCI), as well as richness and abundance of EPT indicator metrics (Ephemeroptera, Plecoptera, Trichoptera), were compared between rural control sites and both transitional and urban stream sites representing varying stages of land use conversion. As compared to non-urban control sites, EPT taxa richness was significantly lower at MS4 urban sites during all three years (p = 0.007 – 0.013) and MS4 transitional sites during one of three years (p=0.48). EPT abundance (%) was significantly lower at MS4 urban sites during all years (p = 0.008 – 0.013) and MS4 transitional sites during one of three years (p=0.34). Mean EPT abundances ranged between 0.6% - 10.3% at urban MS4 sites, and always exceeded 18% at control sites. Both EPT richness and abundance were lower at the MS4 control site but means for EPT and other core metrics at this site were most often similar to non-urban control sites based on analysis of variance (ANOVA). MS4 transitional sites with active development in their watersheds were partially-supporting in their impairment status, and EPT metrics had lower means and generally more variability than control sites. Temporal trends indicate non-urban control and MS4 control sites consistently meet fully-supporting impairment status based on overall MSCI scores, but no study sites currently meet regional expectations (as defined by state reference streams) for either of the EPT metrics. Results indicate that Missouri and Kansas biocriteria for both EPT metrics are not consistently being met at any stream sites in the Kansas City metro area, including fully-supporting control sites and MS4 streams that receive stormwater runoff in watersheds with urban development that is well-established or currently transitioning to urban or suburban land uses.

Missouri↗
USGS2013

Seventy-five years of science—The U.S. Geological Survey’s Western Fisheries Research Center

As of January 2010, 75 years have elapsed since Dr. Frederic Fish initiated the pioneering research program that would evolve into today’s Western Fisheries Research Center (WFRC). Fish began his research working alone in the basement of the recently opened Fisheries Biological Laboratory on Lake Union in Seattle, Washington. WFRC’s research began under the aegis of the U.S. Fish and Wildlife Service and ends its first 75 years as part of the U.S. Geological Survey with a staff of more than 150 biologists and support personnel and a heritage of fundamental research that has made important contributions to our understanding of the biology and ecology of the economically important fish and fish populations of the Nation. Although the current staff may rarely stop to think about it, WFRC’s antecedents extend many years into the past and are intimately involved with the history of fisheries conservation in the Western United States. Thus, WFRC Director Lyman Thorsteinson asked me to write the story of this laboratory “while there are still a few of you around who were here for some of the earlier years” to document the rich history and culture of WFRC by recognizing its many famous scientists and their achievements. This historyalso would help document WFRC’s research ‘footprint’ in the Western United States and its strategic directions. Center Director Thorsteinson concluded that WFRC’s heritage told by an emeritus scientist also would add a texture of legitimacy based on personal knowledge that will all-to-soon be lost to the WFRC and to the USGS. The WFRC story is important for the future as well as for historical reasons. It describes how we got to the place we are today by documenting the origin, original mission, and our evolving role in response to the constantly changing technical information requirements of new environmental legislation and organizational decision-making. The WFRC research program owes its existence to the policy requirements of Federal conservation legislation originating with the construction of Grand Coulee Dam in 1933. The research program was shaped by laws enacted in subsequent years such as the Federal Water Pollution Control Act (1972), National Environmental Policy Act (1973), Endangered Species Act (1974), and Northwest Power Planning Act (1980), to name only a few. The WFRC has not been constrained by direct management or regulatory responsibility for a particular fishery (such as providing sustainable catch limits data to a resource management structure). Thus, WFRC has been able to concentrate on scientific pursuits and information needs required by contemporary environmental legislation. Over the years, we have pioneered in several important areas of fisheries research including the diagnoses and control of diseases in economically important fish, effects of environmental alterations on the physiological quality and survival of Pacific salmon released from federal mitigation hatcheries, applications in biotelemetry, and the bioenergetics of predator-prey interactions in the Columbia River. The WFRC of today is a widely distributed organization in the Western United States. Knowledge of the historical connections and accomplishments of our predecessors is important beyond the sense of pride and unity it instills in the WFRC family of today. For example, a discerning reader will note the evolution of WFRC’s research from a single disciplinary focus (early era—hatchery disease problems), to multiple disciplines (middle to late era—species, populations, habitats; threatened and endangered species), to the present era (multidisciplinary and with increasing process focus). For the benefit of the current WFRC staff, more emphasis has been placed on the early years rather than on the present day because people are quite naturally more familiar with the recent past than with the research done during the first decades of WFRC’s existence. By every rational measure, the WFRC has evolved into a fisheries research organization well positioned to provide the biological information needed to support the continued conservation and management of our Nation’s living aquatic natural resources. The high standard of excellence that connects WFRC’s past to our present research program provides a firm foundation on which to base the work yet to be done. In another 75 years, WFRC will undoubtedly be a very different place than it is today, but its evolution will be forever rooted in the story of the research and of the people related here. More about the diverse fisheries research projects WFRC scientists are conducting today is available at WFRC’s website: http://wfrc.usgs.gov/.

Washington↗
USGS2011

Effects of biologically-active chemical mixtures on fish in a wastewater-impacted urban stream

Stream flow in urban aquatic ecosystems often is maintained by water-reclamation plant (WRP) effluents that contain mixtures of natural and anthropogenic chemicals that persist through the treatment processes. In effluent-impactedstreams, aquatic organisms such as fish are continuously exposed to biologically-activechemicals throughout their life cycles. The North Shore Channel of the Chicago River (Chicago, Illinois) is part of an urban ecosystem in which > 80% of the annual flow consists of effluent from the North Side WRP. In this study, multiple samplings of the effluent and stream water were conducted and fish (largemouth bass and carp) were collected on 2 occasions from the North Shore Channel. Fish also were collected once from the Outer Chicago Harbor in Lake Michigan, a reference site not impacted by WRP discharges. Over 100 organic chemicals with differing behaviors and biological effects were measured, and 23 compounds were detected in all of the water samples analyzed. The most frequently detected and highest concentration (> 100 &mu;g/L) compounds were ethylenediaminetetraacetic acid and 4-nonylphenolmono-to-tetraethoxycarboxylic acids. Other biologically-activechemicals including bisphenol A, 4-nonylphenol, 4-nonylphenolmono-to-tetraethoxylates, 4- tert -octylphenol, and 4- tert -octylphenolmono-to-tetraethoxylates were detected at lower concentrations (< 5 &mu;g/L). The biogenic steroidal hormones 17&beta;-estradiol, estrone, testosterone, 4-androstene-3,17-dione, and cis -androsterone were detected at even lower concentrations (< 0.005 &mu;g/L). There were slight differences in concentrations between the North Side WRP effluent and the North Shore Channel, indicating minimal in-stream attenuation. Fish populations are continuously exposed to mixtures of biologically-activechemicals because of the relative persistency of the chemicals with respect to stream hydraulic residence time, and the lack of a fresh water source for dilution. The majority of male fish exhibited vitellogenin induction, a physiological response consistent with exposure to estrogenic compounds. Tissue-level signs of reproductive disruption, such as ovatestis, were not observed.

Illinois↗
USGS2022

Habitat-specific foraging by striped bass (Morone saxatilis) in the San Francisco Estuary, California: Implications for tidal restoration

Non-native predatory fish strongly impact aquatic communities, and their impacts can be exacerbated by anthropogenic habitat alterations. Loss of natural habitat and restoration actions reversing habitat loss can modify relationships between non-native predators and prey. Predicting how these relationships will change is often difficult because insufficient information exists on the habitat-specific feeding ecology of non-native predators. To address this information gap, we examined diets of non-native Striped Bass ( Morone saxatilis ; 63 to 671 mm standard length; estimated age 1-5 yrs) in the San Francisco Estuary during spring and summer in three habitat types – marsh, shoal, and channel – with the marsh habitat type serving as a model for ongoing and future restoration. Based on a prey-specific index of relative importance, Striped Bass diets were dominated by macroinvertebrates in spring and summer (amphipods in spring, decapods and isopods in summer). In spring, diets were relatively consistent across habitats. In summer, marsh diets were dominated by sphaeromatid isopods and shoal/channel diets by idoteid amphipods and decapods. Striped Bass consumed a variety of native and non-native fishes, primarily Prickly Sculpin ( Cottus asper ) and Gobiidae. The highest importance of fish prey was in the marsh in spring (~40% prey weight), and fish prey comprised less than 25% prey weight in all other season/habitat combinations. Linear discriminant analyses suggested that marsh foraging was prevalent in Striped Bass collected in other habitats, mostly due to the predominance of marsh-associated invertebrates found in the stomachs of individual Striped Bass collected outside of the marsh. Striped Bass diets differ across habitats, with marsh foraging important to Striped Bass regardless of collection location. This information can be used to forecast the potential utilization of restored habitats by this non-native piscivore.

California↗
USGS2023

Watershed- and reach-scale drivers of phosphorus retention and release by streambed sediment in a western Lake Erie watershed during summer

Reducing phosphorus (P) concentrations in aquatic ecosystems, is necessary to improve water quality and reduce the occurrence of harmful cyanobacterial algal blooms. Managing P reduction requires information on the role rivers play in P transport from land to downstream water bodies, but we have a poor understanding of when and where river systems are P sources or sinks. During the summers of 2019 and 2021, we sampled streambed sediment at 78 sites throughout the Maumee River network (a major source of P loads to Lake Erie) focusing on the zero equilibrium P concentration (EPC 0 ), the soluble reactive phosphorus (SRP) concentration at which sediment neither sorbs nor desorbs P. We used structural equation modeling to identify direct and indirect drivers of EPC 0 . Stream sediment was a P sink at 40 % and 67 % of sites in 2019 and 2021, respectively. During both years, spatial variation in EPC 0 was shaped by stream water SRP concentrations, sediment P saturation, and sediment physicochemical characteristics. In turn, SRP concentrations and sediment P saturation (PSR) were influenced by agricultural land use and stream size. Effect of stream size differed among years with stream size having a greater effect on SRP in 2019 and on PSR in 2021. Streambed sediment is currently a net P sink across the sites sampled in the Maumee River network during summer, but sediment at these locations, especially sites in headwater streams, may become a P source if stream water SRP concentrations decrease. Our results improve the understanding of watershed- and reach-scale controls on EPC 0 but also indicate the need for further research on how changes in SRP concentration as a result of conservation management implementation influences the role of streambed sediment in P transport to Lake Erie.

Indiana, Michigan, Ohio↗
USGS2020

Estuarine submerged aquatic vegetation habitat provides organic carbon storage across a shifting landscape

Submerged aquatic vegetation (SAV) thrives across the estuarine salinity gradient providing valuable ecosystem services. Within the saline portion of estuaries, seagrass areas are frequently cited as hotspots for their role in capturing and retaining organic carbon (C org ). Non-seagrass SAV, located in the fresh to brackish estuarine areas, may also retain significant soil C org , yet their role remains unquantified. Given rapidly occurring landscape and salinity changes due to human and natural disturbances, landscape level carbon pool estimates from estuarine SAV habitat blue carbon estimates are needed. We assessed C org stocks in SAV habitat soils from estuarine freshwater to saline habitats (interior deltaic) to saline barrier islands (Chandeleur Island) within the Mississippi River Delta Plain (MRDP), Louisiana, USA. SAV habitats contain C org stocks equivalent to those reported for other estuarine vegetation types (seagrass, salt marsh, mangrove). Interior deltaic SAV C org stocks (231.6 ± 19.5 Mg C org ha −1 ) were similar across the salinity gradient, and significantly higher than at barrier island sites (56.6 ± 10.4 Mg C org ha −1 ). Within the MRDP, shallow water SAV habitat covers up to an estimated 28,000 ha, indicating that soil C org storage is potentially 6.4 ± 0.1 Tg representing an unaccounted C org pool. Extrapolated across Louisiana, and the Gulf of Mexico, this represents a major unaccounted pool of soil C org . As marshes continue to erode, the ability of coastal SAV habitat to offset some of the lost carbon sequestration may be valuable. Our estimates of C org sequestration rates indicated that conversion of eroding marsh to potential SAV habitat may help to offset the reduction of C org sequestration rates. Across Louisiana, we estimated SAV to offset this loss by as much as 79,000 Mg C yr −1 between the 1960s and 2000s.

Louisiana↗