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Cyanobacterial communities of three co-located eutrophic sandpit lakes were surveyed over season and depth using high-throughput DNA sequencing of the 16S rRNA gene. All three lakes were stratified except during April 2017 sampling when... more
Cyanobacterial communities of three co-located eutrophic sandpit lakes were surveyed over season and depth using high-throughput DNA sequencing of the 16S rRNA gene. All three lakes were stratified except during April 2017 sampling when the lakes were recovering from a strong mixing event. 16S rRNA gene V4 sequences were parsed into operational taxonomic units (OTUs) at 99% sequence identity. After rarefaction of 139 samples to 25,000 sequences per sample, a combined total of 921,529 partial 16S rRNA gene sequences were identified as cyanobacteria. They were binned into 19,588 unique cyanobacterial OTUs. Of these OTUs, 11,303 were Cyanobium. Filamentous Planktothrix contributed 1537 and colonial Microcystis contributed 265. The remaining 6482 OTUs were considered unclassified. For Planktothrix and Microcystis one OTU accounted for greater than 95% of the total sequences for each genus. However, in both cases the nondominant OTUs clustered with the dominant OTUs by date, lake and depth. All Planktothrix OTUs and a single Cyanobium OTU were detected below the oxycline. All other Cyanobium and Microcystis OTUs were detected above the oxycline. The distribution of Cyanobium OTUs between lakes and seasons can be explained by an epidemic-like response where individual OTUs clonally rise from a diverse hypolimnion population when conditions are appropriate. The importance of using 99% identity over the more commonly used 97% is discussed with respect to cyanobacterial community structure. The approach described here can provide another valuable tool for assessing cyanobacterial populations and provide greater insight into the controls of cyanobacterial blooms.
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Reliable and accurate streamflow prediction plays a critical role in watershed water resources planning and management. We developed a new hybrid SWAT-WSVR model based on 12 hydrological sites in the Illinois River watershed (IRW), U.S.,... more
Reliable and accurate streamflow prediction plays a critical role in watershed water resources planning and management. We developed a new hybrid SWAT-WSVR model based on 12 hydrological sites in the Illinois River watershed (IRW), U.S., that integrated the Soil and Water Assessment Tool (SWAT) model with a Support Vector Regression (SVR) calibration method coupled with discrete wavelet transforms (DWT) to better support modeling watersheds with limited data availability. Wavelet components of the simulated streamflow from the SWAT-Calibration Uncertainty Procedure (SWAT-CUP) and precipitation time series were used as inputs to SVR to build a hybrid SWAT-WSVR. We examined the performance and potential of the SWAT-WSVR model and compared it with observations, SWAT-CUP, and SWAT-SVR using statistical metrics, Taylor diagrams, and hydrography. The results showed that the average of RMSE-observation’s standard deviation ratio (RSR), Nash–Sutcliffe efficiency (NSE), percent bias (PBIAS),...
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The dataset contains lab analyzed water chemistry and field collected data from hand held sondes.
These data represent the underlying figures and tables of the manuscript.
Cyanobacterial communities of three co-located eutrophic sandpit lakes were surveyed during 2016 and 2017 over season and depth using high-throughput DNA sequencing of the 16S rRNA gene. All three lakes were stratified except during April... more
Cyanobacterial communities of three co-located eutrophic sandpit lakes were surveyed during 2016 and 2017 over season and depth using high-throughput DNA sequencing of the 16S rRNA gene. All three lakes were stratified except during April 2017 when the lakes were recovering from a strong mixing event. 16S rRNA gene V4 sequences were parsed into operational taxonomic units (OTUs) at 99% sequence identity. After rarefaction of 139 samples to 25,000 sequences per sample, a combined total of 921,529 partial 16S rRNA gene sequences were identified as cyanobacteria. They were binned into 19,588 unique cyanobacterial OTUs. Of these OTUs, 11,303 were Cyanobium. Filamentous Planktothrix contributed 1537 and colonial Microcystis contributed 265. The remaining 6482 OTUs were considered unclassified. For Planktothrix and Microcystis one OTU accounted for greater than 95% of the total sequences for each genus. However, in both cases the non-dominant OTUs clustered with the dominant OTUs by date, lake, and depth. All Planktothrix OTUs and a single Cyanobium OTU were detected below the oxycline. All other Cyanobium and Microcystis OTUs were detected above the oxycline. The distribution of Cyanobium OTUs between lakes and seasons can be explained by an epidemic-like response where individual OTUs clonally rise from a diverse hypolimnion population when conditions are appropriate. The importance of using 99% identity over the more commonly used 97% is discussed with respect to cyanobacterial community structure. The approach described here can provide another valuable tool for assessing cyanobacterial populations and provide greater insight into the controls of cyanobacterial blooms.
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Research Interests: Engineering, Geography, Decision Making, Place Attachment, Environmental Management, and 14 morePublic sector, Medicine, Multidisciplinary, Water Supply, Wisconsin, Prediction Model, Environment Design, Dam Removal, Conservation of Natural Resources, River Management, Logistic Model, Social Factor, Environmental, and Department of Natural Resources
Research Interests: Geography, Land tenure, Environmental Management, Environmental Monitoring, Invasive Species, and 15 moreMedicine, Multidisciplinary, Motivation, Humans, Incentive, Easement, Fresh water, Consumer Participation, Conservation Easement, Plant Community, Boolean Satisfiability, Conservation of Natural Resources, Environmental, Personal Satisfaction, and Functional Equivalence
Research Interests: Biomass, Biology, Ecology, Population Dynamics, Biodiversity, and 15 moreExperimental Design, Medicine, Animals, Lotka Volterra, Population Growth, Ecological Succession, Biomass production, Primary Production, Aggregate Productivity, Carrying Capacity, Ecosystem, Interspecific competition, Intraspecific Competition, Ecological Applications, and Microcosm
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Research Interests: Biology, Cyanobacteria, Ecology, Population Dynamics, Environmental Monitoring, and 15 moreDiatoms, Medicine, Ecological Stoichiometry, Aquatic Ecosystem, Bivalvia, Animals, Oklahoma, Feeding Behavior, Nutrient, Ecosystem, Ecological Applications, Mussel, Chlorophyta, nutrient cycle, and Biogeochemical Cycle
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Physiochemical parameters of all the sample sites used in the study.
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Mussel species used in the excretion experiments.
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Large river floodplains present diverse benefits to communities, yet management strategies often fail to consider the broad suite of ecosystem services they provide. The U.S. Environmental Protection Agency (EPA) is evaluating the... more
Large river floodplains present diverse benefits to communities, yet management strategies often fail to consider the broad suite of ecosystem services they provide. The U.S. Environmental Protection Agency (EPA) is evaluating the benefits associated with restoring large river floodplains, with emphasis on the benefits of levee setbacks and revetment removals. This effort will provide scientific support for community-based environmental decision making within our study area on the McKenzie River, a tributary to the Willamette River in Oregon, and support emerging restoration efforts along the Yakima River in Yakima, Washington, and across the nation. The EPA is working with the McKenzie River Trust, the City of Yakima, and the Washington Department of Transportation to bring a more holistic approach to enhance sustainability, with consideration of the ecosystem services offered by dynamic river systems. Restoring hydrologic connectivity in floodplains can enhance the overall ecologi...
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Watershed-scale nonpoint source (NPS) pollution models have become important tools to understand, evaluate, and predict the negative impacts of NPS pollution on water quality. Today, there are many NPS models available for users. However,... more
Watershed-scale nonpoint source (NPS) pollution models have become important tools to understand, evaluate, and predict the negative impacts of NPS pollution on water quality. Today, there are many NPS models available for users. However, different types of models possess different form and structure as well as complexity of computation. It is difficult for users to select an appropriate model for a specific application without a clear understanding of the limitations or strengths for each model or tool. This review evaluates 14 more commonly used watershed-scale NPS pollution models to explain how and when the application of these different models are appropriate for a given effort. The models that are assessed have a wide range of capacities that include simple models used as rapid screening tools (e.g., Long-Term Hydrologic Impact Assessment (L-THIA) and Nonpoint Source Pollution and Erosion Comparison Tool (N-SPECT/OpenNSPECT)), medium-complexity models that require detail data ...
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Soil erosion and lake sediment loading are primary concerns of watershed managers around the world. In the Xinjiang River Basin of China, severe soil erosion occurs primarily during monsoon periods, resulting in sediment flow into Poyang... more
Soil erosion and lake sediment loading are primary concerns of watershed managers around the world. In the Xinjiang River Basin of China, severe soil erosion occurs primarily during monsoon periods, resulting in sediment flow into Poyang Lake and subsequently causing lake water quality deterioration. Here, we identified high-risk soil erosion areas and conditions that drive sediment yield in a watershed system with limited available data to guide localized soil erosion control measures intended to support reduced sediment load into Poyang Lake. We used the Soil and Water Assessment Tool (SWAT) model to simulate monthly and annual sediment yield based on a calibrated SWAT streamflow model, identified where sediment originated, and determined what geographic factors drove the loading within the watershed. We applied monthly and daily streamflow discharge (1985–2009) and monthly suspended sediment load data (1985–2001) to Meigang station to conduct parameter sensitivity analysis, calib...
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Hyporheic zones contribute to lower temperatures in many rivers, creating a longitudinal heterogeneous array of thermal refuges. In this study, we had the unique opportunity to show temperature reduction along hyporheic zone pathlines in... more
Hyporheic zones contribute to lower temperatures in many rivers, creating a longitudinal heterogeneous array of thermal refuges. In this study, we had the unique opportunity to show temperature reduction along hyporheic zone pathlines in a large river system that contribute to the maintenance of refuges through discharge into off‐channel habitats. Temperature was monitored in a dense network of wells that were located along pathlines in small islands, determined from a calibrated groundwater flow model. Temperature along one 600‐m pathline was reduced about 7° C. Among three islands that were adjacent to the river, the northern two showed exponential decrease in temperature with distance, with fitted thermal Péclet numbers of 2.7 and 6.5, whereas the southern island showed no significant decrease. We suggest that this is due to the higher infiltration rate in the wet season in this larger, more mature island, which suppresses hyporheic flow in the wet season.Stable isotope sampling ...
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Background/Question/Methods Watersheds have a profound capacity to retain and remove nitrogen (N) inputs before entering coastal waters thereby minimizing eutrophication and hypoxia in estuarine waters. Research suggests that much of this... more
Background/Question/Methods Watersheds have a profound capacity to retain and remove nitrogen (N) inputs before entering coastal waters thereby minimizing eutrophication and hypoxia in estuarine waters. Research suggests that much of this N cycling occurs within aquatic ecosystems, e.g., lakes, streams and wetlands, which may become “hotspots” of nitrous oxide (N2O) production. We examined the effects of woody debris on nitrate removal and denitrification rates in streams of different N enrichment levels. Three different standardized substrates (fresh wood blocks, bundles of naturally occurring streambed wood, and clay‐fired blocks) that were expected to vary in their pool of labile carbon were incubated for 8‐10 weeks in each stream - a high nitrate agricultural stream in Pennsylvania and a low nitrate forested stream in Rhode Island. Substrates were collected and subjected to a series of lab‐based mesocosm assays in stream water amended with 15N-labeled nitrate-N. Nitrate removal ...
ABSTRACT The Willamette River is a ninth-order tributary of the Columbia which passes through a productive and populous region in northwest Oregon. Where unconstrained by shoreline revetments, the floodplain of this river is a... more
ABSTRACT The Willamette River is a ninth-order tributary of the Columbia which passes through a productive and populous region in northwest Oregon. Where unconstrained by shoreline revetments, the floodplain of this river is a high-energy, dynamic system which supports a variety of riparian forests and floodplain habitats. On the Green Island Restoration Site, north of the city of Eugene, several geomorphological features common to much of the Willamette floodplain are present. These features, ranging from young bare gravel bars, islands supporting mature forest stands, to agricultural areas bounded by levees. As part of a Memorandum of Understanding with the McKenzie River Trust, USEPA has constructed a network of fifty shallow monitoring wells on the Green Island site. Among the purposes are to characterize the hydrogeology of the multiple- island floodplain, the extent of hyporheic flow, and the temperature regime. The monitoring wells are located in areas ranging from a few meters from the river edge to several hundred meters away, within the agricultural areas. By automatic data-logging, flow nets will be developed using numerical modeling. Water quality data will be collected to measure the degee to which subsurface biogeochemistry is influenced by geomorphologic features that are determined by the processes of river channel migration, island formation, and colonization by riparian forest. The monitoring network will also be used to measure the groundwater quality effects of restoration projects currently underway. These include reforestation of previously agricultural areas, and levee removal.
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ABSTRACT Background/Question/Methods Large river floodplains are poor nitrate pollution buffers when polluted groundwater moves beneath biogeochemically retentive zones prior to entering the main channel. However, in floodplain regions... more
ABSTRACT Background/Question/Methods Large river floodplains are poor nitrate pollution buffers when polluted groundwater moves beneath biogeochemically retentive zones prior to entering the main channel. However, in floodplain regions with extensive backwaters and organic carbon accumulation, surface waters may interact with groundwater to support enhanced denitrification in the subsurface and provide a sink for nitrate pollution. Here, we evaluate the spatial heterogeneity and patterns of nitrate and denitrification in the shallow groundwater of a large river floodplain to determine the controls and find predictable indicators of enhanced denitrification to better identify habitats for restoration and preservation that enhance pollution removal. Green Island, part of the Willamette River floodplain, near Coburg, Oregon is under active restoration, led by the McKenzie River Trust, to hydrologically re-connect the Willamette to its historic floodplain and re-establish native vegetation. We measured rates of denitrification using an in-situ push-pull technique with 15N isotopic tracers injected into shallow groundwater ~0.5m below the water table across the floodplain from 0.5-4m below the sediment surface. These denitrification rates, combined with quarterly sampled nutrient concentration, ambient isotopes of N and O in nitrate, and evaluation of subsurface hydrology will help identify habitats that support enhanced denitrification and guide future restoration activities in the region. Results/Conclusions Subsurface denitrification rates at Green Island span three orders of magnitude across the floodplain (Mean 57.1±17.8 µMol Kg-1D-1n=31) with the greatest rates beneath wet habitats (Max 307.7) and lowest in those areas with the greatest depth to groundwater (Min 3.65 to below detection). Denitrification rates in the subsurface are correlated negatively with elevation (ρ=-0.48 p<0.01) and positively with both dissolved organic carbon (0.45 p<0.01) and iron (0.44 p<0.01). These results suggest that obvious areas of groundwater and surface water interaction with reduced conditions, like backwater sloughs and wetlands, are indicators of subsurface denitrification and may govern subsurface processes. We found that several measures that typically indicate denitrification like enriched 15N-NO3 and N2O concentration are not correlated with measured denitrification rates, owing to the integrative nature of those measures along diverse flow paths compared to the site specificity of push-pull measurements. Based on these preliminary results, lower elevation wet regions that contribute organic carbon to the subsurface possess greater potential to denitrify nitrate at Green Island and are an indicator of a potentially valuable nitrate sink in floodplain restoration. This is an abstract of a proposed presentation and does not necessarily reflect EPA policy.
ABSTRACT Background/Question/Methods The groundwater–surface water interface, consisting of shallow groundwater adjacent to stream channels, is a hot spot for nitrogen removal processes, a storage zone for other solutes, and a target for... more
ABSTRACT Background/Question/Methods The groundwater–surface water interface, consisting of shallow groundwater adjacent to stream channels, is a hot spot for nitrogen removal processes, a storage zone for other solutes, and a target for restoration activities. Characterizing groundwater-surface water interaction is difficult because of physical obstacles to sampling. We present results from high spatial-resolution surface water nutrient sampling (“sampling slam”) that revealed groundwater-surface water interactions and biochemical patterns at two streams in the Chesapeake Bay watershed. Results/Conclusions Despite considerable reach-scale variability, we observed consistent longitudinal patterns in biogeochemistry. For example, specific conductivity and chloride clearly showed the effects of road salts at storm-water outfall pipes and where the stream flowed under a major freeway. Groundwater was a reservoir for chloride, leading to chronically elevated surface water concentrations. Our sampling slam approach also revealed strong, consistent relationships among dissolved organic carbon, nitrate nitrogen and sulfate that were driven by both biological transformations (e.g. denitrification) and by hydrologic connectivity between groundwater and surface water. Therefore, nitrogen transformations that occur in groundwater could be reflected in surface water chemistry patterns when streams are at base flow. Our results demonstrated the importance of understanding groundwater ecology in order to interpret stream chemistry patterns and subsequently apply best management practices. Monitoring at high spatial resolution and beyond the stream-reach scale is recommended for evaluation of biogeochemical function in streams, especially in urban ecosystems and where there are various point and non-point sources of nutrients.
Background/Question/Methods Watersheds have a profound capacity to retain and remove nitrogen (N) inputs before entering coastal waters thereby minimizing eutrophication and hypoxia in estuarine waters. Research suggests that much of this... more
Background/Question/Methods Watersheds have a profound capacity to retain and remove nitrogen (N) inputs before entering coastal waters thereby minimizing eutrophication and hypoxia in estuarine waters. Research suggests that much of this N cycling occurs within aquatic ecosystems, e.g., lakes, streams and wetlands, which may become “hotspots” of nitrous oxide (N2O) production. We examined the effects of woody debris on nitrate removal and denitrification rates in streams of different N enrichment levels. Three different standardized substrates (fresh wood blocks, bundles of naturally occurring streambed wood, and clay‐fired blocks) that were expected to vary in their pool of labile carbon were incubated for 8‐10 weeks in each stream - a high nitrate agricultural stream in Pennsylvania and a low nitrate forested stream in Rhode Island. Substrates were collected and subjected to a series of lab‐based mesocosm assays in stream water amended with 15N-labeled nitrate-N. Nitrate removal ...
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Friday, August 7, 2009 - 8:40 AM COS 125-3: Low elevation inland habitats of the Willamette River floodplain support enhanced denitrification. Kenneth J. Forshay, Barton R. Faulkner, Paul Mayer, and Steven P. Cline. United States... more
Friday, August 7, 2009 - 8:40 AM COS 125-3: Low elevation inland habitats of the Willamette River floodplain support enhanced denitrification. Kenneth J. Forshay, Barton R. Faulkner, Paul Mayer, and Steven P. Cline. United States Environmental Protection Agency. ...
Research Interests: Geography, Microbial Ecology, Ecology, Nitrogen Cycle, Ecosystem ecology, and 15 moreEnvironmental Change, Discipline, Land Use Change, Biological Sciences, Global change, Environmental Sciences, Interdisciplinary research, Case Study, Macro, Nitrogen, Ecosystem, Land Use Cover Change, Ecosystem Function, Interdisciplinary Collaboration, and Microbial community
Nutrient cycling is a key process linking organisms in ecosystems. This is especially apparent in stream environments in which nutrients are taken up readily and cycled through the system in a downstream trajectory. Ecological... more
Nutrient cycling is a key process linking organisms in ecosystems. This is especially apparent in stream environments in which nutrients are taken up readily and cycled through the system in a downstream trajectory. Ecological stoichiometry predicts that biogeochemical cycles of different elements are interdependent because the organisms that drive these cycles require fixed ratios of nutrients. There is growing recognition that animals play an important role in biogeochemical cycling across ecosystems. In particular, dense aggregations of consumers can create biogeochemical hotspots in aquatic ecosystems via nutrient translocation. We predicted that filter‐feeding freshwater mussels, which occur as speciose, high‐biomass aggregates, would create biogeochemical hotspots in streams by altering nutrient limitation and algal dynamics. In a field study, we manipulated nitrogen and phosphorus using nutrient‐diffusing substrates in areas with high and low mussel abundance, recorded algal ...