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Sample records for intermittent headwater streams

  1. The role of headwater streams in downstream water quality

    Science.gov (United States)

    Alexander, R.B.; Boyer, E.W.; Smith, R.A.; Schwarz, G.E.; Moore, R.B.

    2007-01-01

    Knowledge of headwater influences on the water-quality and flow conditions of downstream waters is essential to water-resource management at all governmental levels; this includes recent court decisions on the jurisdiction of the Federal Clean Water Act (CWA) over upland areas that contribute to larger downstream water bodies. We review current watershed research and use a water-quality model to investigate headwater influences on downstream receiving waters. Our evaluations demonstrate the intrinsic connections of headwaters to landscape processes and downstream waters through their influence on the supply, transport, and fate of water and solutes in watersheds. Hydrological processes in headwater catchments control the recharge of subsurface water stores, flow paths, and residence times of water throughout landscapes. The dynamic coupling of hydrological and biogeochemical processes in upland streams further controls the chemical form, timing, and longitudinal distances of solute transport to downstream waters. We apply the spatially explicit, mass-balance watershed model SPARROW to consider transport and transformations of water and nutrients throughout stream networks in the northeastern United States. We simulate fluxes of nitrogen, a primary nutrient that is a water-quality concern for acidification of streams and lakes and eutrophication of coastal waters, and refine the model structure to include literature observations of nitrogen removal in streams and lakes. We quantify nitrogen transport from headwaters to downstream navigable waters, where headwaters are defined within the model as first-order, perennial streams that include flow and nitrogen contributions from smaller, intermittent and ephemeral streams. We find that first-order headwaters contribute approximately 70% of the mean-annual water volume and 65% of the nitrogen flux in second-order streams. Their contributions to mean water volume and nitrogen flux decline only marginally to about 55% and

  2. Headwater stream temperature: interpreting response after logging, with and without riparian buffers, Washington, USA

    Science.gov (United States)

    Jack E. Janisch; Steven M. Wondzell; William J. Ehinger

    2012-01-01

    We examined stream temperature response to forest harvest in small forested headwater catchments in western Washington, USA over a seven year period (2002-2008). These streams have very low discharge in late summer and many become spatially intermittent. We used a before-after, control-impact (BACl) study design to contrast the effect of clearcut logging with two...

  3. Salamander occupancy in headwater stream networks

    Science.gov (United States)

    Grant, E.H.C.; Green, L.E.; Lowe, W.H.

    2009-01-01

    1. Stream ecosystems exhibit a highly consistent dendritic geometry in which linear habitat units intersect to create a hierarchical network of connected branches. 2. Ecological and life history traits of species living in streams, such as the potential for overland movement, may interact with this architecture to shape patterns of occupancy and response to disturbance. Specifically, large-scale habitat alteration that fragments stream networks and reduces connectivity may reduce the probability a stream is occupied by sensitive species, such as stream salamanders. 3. We collected habitat occupancy data on four species of stream salamanders in first-order (i.e. headwater) streams in undeveloped and urbanised regions of the eastern U.S.A. We then used an information-theoretic approach to test alternative models of salamander occupancy based on a priori predictions of the effects of network configuration, region and salamander life history. 4. Across all four species, we found that streams connected to other first-order streams had higher occupancy than those flowing directly into larger streams and rivers. For three of the four species, occupancy was lower in the urbanised region than in the undeveloped region. 5. These results demonstrate that the spatial configuration of stream networks within protected areas affects the occurrences of stream salamander species. We strongly encourage preservation of network connections between first-order streams in conservation planning and management decisions that may affect stream species.

  4. Changes in vegetative communities and water table dynamics following timber harvesting in small headwater streams

    Science.gov (United States)

    B. Choi; J.C. Dewey; J. A. Hatten; A.W. Ezell; Z. Fan

    2012-01-01

    In order to better understand the relationship between vegetation communities and water table in the uppermost portions (ephemeral–intermittent streams) of headwater systems, seasonal plot-based field characterizations of vegetation were used in conjunction with monthly water table measurements. Vegetation, soils, and water table data were examined to determine...

  5. Stream Width Dynamics in a Small Headwater Catchment

    Science.gov (United States)

    Barefoot, E. A.; Pavelsky, T.; Allen, G. H.; Zimmer, M. A.; McGlynn, B. L.

    2016-12-01

    Changing streamflow conditions cause small, ephemeral and intermittent stream networks to expand and contract, while simultaneously driving widening and narrowing of streams. The resulting dynamic surface area of ephemeral streams impacts critical hydrological and biogeochemical processes, including air-water gas exchange, solute transport, and sediment transport. Despite the importance of these dynamics, to our knowledge there exists no complete study of how stream widths vary throughout an entire catchment in response to changing streamflow conditions. Here we present the first characterization of how variable hydrologic conditions impact the distribution of stream widths in a 48 ha headwater catchment in the Stony Creek Research Watershed, NC, USA. We surveyed stream widths longitudinally every 5 m on 12 occasions over a range of stream discharge from 7 L/s to 128 L/s at the catchment outlet. We hypothesize that the shape and location of the stream width distribution are driven by the action of two interrelated mechanisms, network extension and at-a-station widening, both of which increase with discharge. We observe that during very low flow conditions, network extension more significantly influences distribution location, and during high flow conditions stream widening is the dominant driver. During moderate flows, we observe an approximately 1 cm rightward shift in the distribution peak with every additional 10 L/s of increased discharge, which we attribute to a greater impact of at-a-station widening on distribution location. Aside from this small shift, the qualitative location and shape of the stream width distribution are largely invariant with changing streamflow. We suggest that the basic characteristics of stream width distributions constitute an equilibrium between the two described mechanisms across variable hydrologic conditions.

  6. Effect of timber harvesting on stormflow characteristics in headwater streams of managed, forested watersheds in the Upper Gulf Coastal Plain in Mississippi

    Science.gov (United States)

    Byoungkoo Choi; Jeff A. Hatten; Janet C. Dewey; Kyoichi Otsuki; Dusong Cha

    2013-01-01

    Headwater streams are crucial parts of overall watershed dynamics because they comprise more than 50–80% of stream networks and watershed land areas. This study addressed the influence of headwater areas (ephemeral and intermittent) on stormflow characteristics following harvest within three first–order catchments in the Upper Gulf Coastal Plain of Mississippi. Four...

  7. Operational Draft Regional Guidebook for the Functional Assessment of High-gradient Ephemeral and Intermittent Headwater Streams in Western West Virginia and Eastern Kentucky

    Science.gov (United States)

    2010-07-01

    Liriodendron tulipifera tuliptree Ulmus rubra slippery elm Magnolia acuminata cucumber-tree Ulmus thomasii rock elm ERDC/EL TR-10-11 103 Watershed...americana American elm ERDC/EL TR-10-11 41 0 0.5 1 1.5 2 2.5 SRV per 100 feet of stream reach 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Va ria bl e S...canadensis eastern hemlock Juglans nigra black walnut Ulmus americana American elm Liquidambar styraciflua sweetgum Ulmus parvifolia Chinese elm

  8. Structures linking physical and biological processes in headwater streams of the Maybeso watershed, Southeast Alaska

    Science.gov (United States)

    Mason D. Bryant; Takashi Gomi; Jack J. Piccolo

    2007-01-01

    We focus on headwater streams originating in the mountainous terrain of northern temperate rain forests. These streams rapidly descend from gradients greater than 20% to less than 5% in U-shaped glacial valleys. We use a set of studies on headwater streams in southeast Alaska to define headwater stream catchments, link physical and biological processes, and describe...

  9. The long term response of stream flow to climatic warming in headwater streams of interior Alaska

    Science.gov (United States)

    Jeremy B. Jones; Amanda J. Rinehart

    2010-01-01

    Warming in the boreal forest of interior Alaska will have fundamental impacts on stream ecosystems through changes in stream hydrology resulting from upslope loss of permafrost, alteration of availability of soil moisture, and the distribution of vegetation. We examined stream flow in three headwater streams of the Caribou-Poker Creeks Research Watershed (CPCRW) in...

  10. Ammonium release from a blanket peatland into headwater stream systems

    International Nuclear Information System (INIS)

    Daniels, S.M.; Evans, M.G.; Agnew, C.T.; Allott, T.E.H.

    2012-01-01

    Hydrochemical sampling of South Pennine (UK) headwater streams draining eroded upland peatlands demonstrates these systems are nitrogen saturated, with significant leaching of dissolved inorganic nitrogen (DIN), particularly ammonium, during both stormflow and baseflow conditions. DIN leaching at sub-catchment scale is controlled by geomorphological context; in catchments with low gully densities ammonium leaching dominates whereas highly gullied catchments leach ammonium and nitrate since lower water tables and increased aeration encourages nitrification. Stormflow flux calculations indicate that: approximately equivalent amounts of nitrate are deposited and exported; ammonium export significantly exceeds atmospheric inputs. This suggests two ammonium sources: high atmospheric loadings; and mineralisation of organic nitrogen stored in peat. Downstream trends indicate rapid transformation of leached ammonium into nitrate. It is important that low-order headwater streams are adequately considered when assessing impacts of atmospheric loads on the hydrochemistry of stream networks, especially with respect to erosion, climate change and reduced precipitation. - Highlights: ► Headwaters draining eroded South Pennine (UK) peatlands are nitrogen saturated. ► Ammonium and nitrate leaching arises from aeration due to lower water tables. ► Nitrate deposition equals export during storms; ammonium export exceeds input. ► Ammonia input from high atmospheric loading and mineralisation of organic nitrogen. ► Downstream nitrogen trends indicate rapid transformation of ammonium into nitrate. - Inorganic nitrogen leaching from South Pennine peatlands is dominated by ammonium that is rapidly transformed within-streams to nitrate.

  11. Soil Microbial Community Contribution to Small Headwater Stream Metabolism.

    Science.gov (United States)

    Clapcott, J. E.; Gooderham, J. P.; Barmuta, L. A.; Davies, P. E.

    2005-05-01

    The temporal dynamics of sediment respiration were examined in seven small headwater streams in forested catchments in 2004. A strong seasonal response was observed with higher respiration rates in depositional zones than in gravel runs. The data were also examined in the context of proportional habitat distributions that highlighted the importance of high flow events in shaping whole stream metabolic budgets. This study specifically examines the question of terrestrial soil respiration contribution to whole stream metabolism by the controlled inundation of terrestrial soils. The experiment included six experimentally inundated terrestrial zones, six terrestrial controls, and six in-stream depositional zones. Sediment bacterial respiration was measured using 14C leucine incorporation and cotton strip bioassays were also employed to provide an indicative measure of sediment microbial activity. Despite high variability and exhibiting significantly lower bacterial activity than in-stream sediments, modelling using flow data and habitat mapping illustrated the important contribution of terrestrial soil respiration to the whole stream metabolic budgets of small headwater streams. In addition, microbial community composition examined using phospholipid fatty acid analysis clearly differentiated between terrestrial and aquatic communities. Freshly inundated terrestrial communities remained similar to un-inundated controls after 28 days.

  12. Effects of riparian buffer width on wood loading in headwater streams after repeated forest thinning

    Science.gov (United States)

    Julia I. Burton; Deanna H. Olson; Klaus J. Puettmann

    2016-01-01

    Forested riparian buffer zones are used in conjunction with upland forest management, in part, to provide for the recruitment for large wood to streams. Small headwater streams account for the majority of stream networks in many forested regions. Yet, our understanding of how riparian buffer width influences wood dynamics in headwater streams is relatively less...

  13. Seasonal pattern of anthropogenic salinization in temperate forested headwater streams.

    Science.gov (United States)

    Timpano, Anthony J; Zipper, Carl E; Soucek, David J; Schoenholtz, Stephen H

    2018-04-15

    Salinization of freshwaters by human activities is of growing concern globally. Consequences of salt pollution include adverse effects to aquatic biodiversity, ecosystem function, human health, and ecosystem services. In headwater streams of the temperate forests of eastern USA, elevated specific conductance (SC), a surrogate measurement for the major dissolved ions composing salinity, has been linked to decreased diversity of aquatic insects. However, such linkages have typically been based on limited numbers of SC measurements that do not quantify intra-annual variation. Effective management of salinization requires tools to accurately monitor and predict salinity while accounting for temporal variability. Toward that end, high-frequency SC data were collected within the central Appalachian coalfield over 4 years at 25 forested headwater streams spanning a gradient of salinity. A sinusoidal periodic function was used to model the annual cycle of SC, averaged across years and streams. The resultant model revealed that, on average, salinity deviated approximately ±20% from annual mean levels across all years and streams, with minimum SC occurring in late winter and peak SC occurring in late summer. The pattern was evident in headwater streams influenced by surface coal mining, unmined headwater reference streams with low salinity, and larger-order salinized rivers draining the study area. The pattern was strongly responsive to varying seasonal dilution as driven by catchment evapotranspiration, an effect that was amplified slightly in unmined catchments with greater relative forest cover. Evaluation of alternative sampling intervals indicated that discrete sampling can approximate the model performance afforded by high-frequency data but model error increases rapidly as discrete sampling intervals exceed 30 days. This study demonstrates that intra-annual variation of salinity in temperate forested headwater streams of Appalachia USA follows a natural seasonal

  14. Headwater biodiversity among different levels of stream habitat hierarchy

    DEFF Research Database (Denmark)

    Göthe, Emma; Friberg, Nikolai; Kahlert, Maria

    2014-01-01

    of a- and b-diversity to y-diversity between two levels of stream habitat hierarchy (catchment and region level). The relationship between species community structure and local environmental factors was also assessed. Our results show that both a- and b-diversity made a significant contribution to y......-diversity. b-diversity remained relatively constant between the two levels of habitat hierarchy even though local environmental control of the biota decreased from the catchment to the region level. To capture most of headwater y-diversity, management should therefore target sites that are locally diverse......, but at the same time select sites so that b-diversity is maximized. As environmental control of the biota peaked at the catchment level, the conservation of headwater stream diversity is likely to be most effective when management targets environmental conditions across multiple local sites within relatively...

  15. Hydrologic connectivity and the contribution of stream headwaters to ecological integrity at regional scales

    Science.gov (United States)

    Freeman, Mary C.; Pringle, C.M.; Jackson, C.R.

    2007-01-01

    Cumulatively, headwater streams contribute to maintaining hydrologic connectivity and ecosystem integrity at regional scales. Hydrologic connectivity is the water-mediated transport of matter, energy and organisms within or between elements of the hydrologic cycle. Headwater streams compose over two-thirds of total stream length in a typical river drainage and directly connect the upland and riparian landscape to the rest of the stream ecosystem. Altering headwater streams, e.g., by channelization, diversion through pipes, impoundment and burial, modifies fluxes between uplands and downstream river segments and eliminates distinctive habitats. The large-scale ecological effects of altering headwaters are amplified by land uses that alter runoff and nutrient loads to streams, and by widespread dam construction on larger rivers (which frequently leaves free-flowing upstream portions of river systems essential to sustaining aquatic biodiversity). We discuss three examples of large-scale consequences of cumulative headwater alteration. Downstream eutrophication and coastal hypoxia result, in part, from agricultural practices that alter headwaters and wetlands while increasing nutrient runoff. Extensive headwater alteration is also expected to lower secondary productivity of river systems by reducing stream-system length and trophic subsidies to downstream river segments, affecting aquatic communities and terrestrial wildlife that utilize aquatic resources. Reduced viability of freshwater biota may occur with cumulative headwater alteration, including for species that occupy a range of stream sizes but for which headwater streams diversify the network of interconnected populations or enhance survival for particular life stages. Developing a more predictive understanding of ecological patterns that may emerge on regional scales as a result of headwater alterations will require studies focused on components and pathways that connect headwaters to river, coastal and

  16. Stream Intermittency Sensors Monitor the Onset and Duration of Stream Flow Along a Channel Network During Storms

    Science.gov (United States)

    Jensen, C.; McGuire, K. J.

    2017-12-01

    Headwater streams are spatially extensive, accounting for a majority of global stream length, and supply downstream water bodies with water, sediment, organic matter, and pollutants. Much of this transmission occurs episodically during storms when stream flow and connectivity are high. Many headwaters are temporary streams that expand and contract in length in response to storms and seasonality. Understanding where and when streams carry flow is critical for conserving headwaters and protecting downstream water quality, but storm events are difficult to study in small catchments. The rise and fall of stream flow occurs rapidly in headwaters, making observation of the entire stream network difficult. Stream intermittency sensors that detect the presence or absence of water can reveal wetting and drying patterns over short time scales. We installed 50 intermittency sensors along the channel network of a small catchment (35 ha) in the Valley and Ridge of southwest Virginia. Previous work shows stream length is highly variable in this shale catchment, as the drainage density spans two orders of magnitude. The sensors record data every 15 minutes for one year to capture different seasons, antecedent moisture conditions, and precipitation rates. We seek to determine whether hysteresis between stream flow and network length occurs on the rising and falling limbs of events and if reach-scale characteristics such as valley width explain spatial patterns of flow duration. Our results indicate reaches with a wide, sediment-filled valley floor carry water for shorter periods of time than confined channel segments with steep valley side slopes. During earlier field mapping surveys, we only observed flow in a few of the tributaries for the wettest conditions mapped. The sensors now show that these tributaries flow more frequently during much smaller storms, but only for brief periods of time (hour). The high temporal sampling resolution of the sensors permits a more realistic

  17. Characterization and classification of invertebrates as indicators of flow permanence in headwater streams

    Science.gov (United States)

    Headwater streams represent a large proportion of river networks and many have temporary flow. Litigation has questioned whether these streams are jurisdictional under the Clean Water Act. Our goal was to identify indicators of flow permanence by comparing invertebrate assemblage...

  18. Larval salamanders and channel geomorphology are indicators of hydrologic permanence in forested headwater streams

    Science.gov (United States)

    Regulatory agencies need rapid indicators of hydrologic permanence for jurisdictional determinations of headwater streams. Our study objective was to assess the utility of larval salamander presence and assemblage structure and habitat variables for determining stream permanence ...

  19. Vertebrate assemblages associated with headwater hydrology in western Oregon managed forests.

    Science.gov (United States)

    D.H. Olson; G. Weaver

    2007-01-01

    We characterized headwater stream habitats, fish, and amphibian fauna, in and along 106 headwater stream reaches at 12 study sites within managed forest stands 40 to 70 years old in western Oregon. Headwater stream types in our sample included perennial, spatially intermittent, and dry reaches. We captured 454 fish of three species groups and 1,796 amphibians of 12...

  20. Ecoregion and land-use influence invertebrate and detritus transport from headwater streams

    Science.gov (United States)

    Binckley, Christopher A.; Wipfli, Mark S.; Medhurst, R. Bruce; Polivka, Karl; Hessburg, Paul F.; Salter, R. Brion; Kill, Joshua Y.

    2010-01-01

    Summary 1. Habitats are often connected by fluxes of energy and nutrients across their boundaries. For example, headwater streams are linked to surrounding riparian vegetation through invertebrate and leaf litter inputs, and there is evidence that consumers in downstream habitats are subsidised by resources flowing from headwater systems. However, the strength of these linkages and the manner in which potential headwater subsidies vary along climatic and disturbance gradients are unknown.

  1. A catchment scale evaluation of multiple stressor effects in headwater streams

    DEFF Research Database (Denmark)

    Rasmussen, J. J.; McKnight, Ursula S.; Loinaz, Maria Christina

    2013-01-01

    studied 11 headwater streams in the Hove catchment in the Copenhagen region. All sites had substantial physical habitat and water quality impairments due to anthropogenic influence (intensive agriculture, urban settlements, contaminated sites and low base-flow due to water abstraction activities...... insecticides were probably essential contributors to the overall ecological impairment of these streams. Our results suggest that headwater streams should be considered in future management and mitigation plans. Catchment-based management is necessary because several anthropogenic stressors exceeded...

  2. Coupling nutrient uptake and energy flow in headwater streams

    Energy Technology Data Exchange (ETDEWEB)

    Mulholland, Patrick J [ORNL; Fellows, Christine [Griffith University, Nathan, Queensland, Australia; Valett, H. Maurice [Virginia Polytechnic Institute and State University (Virginia Tech); Dahm, Cliff [University of New Mexico, Albuquerque; Thomas, Steve [University of Nebraska

    2006-08-01

    Nutrient cycling and energy flow in ecosystems are tightly linked through the metabolic processes of organisms. Greater uptake of inorganic nutrients is expected to be associated with higher rates of metabolism [gross primary production (GPP) and respiration (R)], due to assimilatory demand of both autotrophs and heterotrophs. However, relationships between uptake and metabolism should vary with the relative contribution of autochthonous and allochthonous sources of organic matter. To investigate the relationship between metabolism and nutrient uptake, we used whole-stream and benthic chamber methods to measure rates of nitrate-nitrogen (NO{sub 3}-N) uptake and metabolism in four headwater streams chosen to span a range of light availability and therefore differing rates of GPP and contributions of autochthonous carbon. We coupled whole-stream metabolism with measures of NO{sub 3}-N uptake conducted repeatedly over the same stream reach during both day and night, as well as incubating benthic sediments under both light and dark conditions. NO{sub 3}-N uptake was generally greater in daylight compared to dark conditions, and although day-night differences in whole-stream uptake were not significant, light-dark differences in benthic chambers were significant at three of the four sites. Estimates of N demand indicated that assimilation by photoautotrophs could account for the majority of NO{sub 3}-N uptake at the two sites with relatively open canopies. Contrary to expectations, photoautotrophs contributed substantially to NO{sub 3}-N uptake even at the two closed-canopy sites, which had low values of GPP/R and relied heavily on allochthonous carbon to fuel R.

  3. Carbon pools along headwater streams with differing valley geometry in Rocky Mountain National Park, Colorado (Abstract)

    Science.gov (United States)

    Kathleen A. Dwire; Ellen E. Wohl; Nicholas A. Sutfin; Roberto A. Bazan; Lina Polvi-Pilgrim

    2012-01-01

    Headwaters are known to be important in the global carbon cycle, yet few studies have investigated carbon (C) pools along stream-riparian corridors. To better understand the spatial distribution of C storage in headwater fluvial networks, we estimated above- and below-ground C pools in 100-m-long reaches in six different valley types in Rocky Mountain National Park,...

  4. Stream carbon dynamics in low-gradient headwaters of a forested watershed

    Science.gov (United States)

    April Bryant-Mason; Y. Jun Xu; Johnny M. Grace

    2013-01-01

    Headwater streams drain more than 70 percent of the total watershed area in the United States. Understanding of carbon dynamics in the headwater systems is of particular relevance for developing best silvicultural practices to reduce carbon export. This study was conducted in a low-gradient, predominantly forested watershed located in the Gulf Coastal Plain region, to...

  5. Groundwater Contributions to Intermittent Streamflow in a Headwater Catchment: How do Geoclimatic Controls Influence Downstream Water Quality?

    Science.gov (United States)

    Smull, E. M.; Gooseff, M. N.; Singha, K.

    2014-12-01

    Hydrologic connectivity of headwater catchments affects surface water yield and quality of downstream drinking water supplies. Lower Gordon Gulch, a 2.75 km2 catchment, is part of the Boulder Creek watershed - the primary drinking water supply for the city of Boulder, Colorado. We hypothesize that the geologic and climatic environment within the catchment controls the magnitude, timing, and duration of hydrologic connection between the landscape and the stream, and thus the distribution of major ions to the surface water. Specifically, bedrock patterns, vegetation type and density, and snowpack dynamics influence how precipitation inputs move from the hillslopes to the catchment outlet. Preliminary results suggest that north-facing hillslopes with steeper slopes, deeper weathering of bedrock, denser vegetation stands, and a seasonal snowpack, provide consistently greater groundwater inputs to the stream compared to the south-facing hillslopes. We believe that this is in part due to subsurface bedrock patterns forcing a dominate cross-valley gradient. Through an extensive observation network of hillslope wells, periodic stream water balance measurements, and synoptic chemistry samples, we plan to continue our assessment of the spatio-temporal connectivity dynamics throughout the seasonal dry down (late summer through winter), during which streamflow can be intermittent. Results will help to guide landuse practices of upland catchments with respect to their role in Boulder's drinking water supply.

  6. Aquatic insect assemblages associated with subalpine stream segment types in relict glaciated headwaters

    Science.gov (United States)

    Kubo, Joshua S.; Torgersen, Christian E.; Bolton, Susan M.; Weekes, Anne A.; Gara, Robert I.

    2013-01-01

    1. Aquatic habitats and biotic assemblages in subalpine headwaters are sensitive to climate and human impacts. Understanding biotic responses to such perturbations and the contribution of high-elevation headwaters to riverine biodiversity requires the assessment of assemblage composition among habitat types. We compared aquatic insect assemblages among headwater stream segment types in relict glaciated subalpine basins in Mt. Rainier National Park, Washington, USA. 2. Aquatic insects were collected during summer and autumn in three headwater basins. In each basin, three different stream segment types were sampled: colluvial groundwater sources, alluvial lake inlets, and cascade-bedrock lake outlets. Ward's hierarchical cluster analysis revealed high β diversity in aquatic insect assemblages, and non-metric multidimensional scaling indicated that spatial and temporal patterns in assemblage composition differed among headwater stream segment types. Aquatic insect assemblages showed more fidelity to stream segment types than to individual basins, and the principal environmental variables associated with assemblage structure were temperature and substrate. 3. Indicator species analyses identified specific aquatic insects associated with each stream segment type. Several rare and potentially endemic aquatic insect taxa were present, including the recently described species, Lednia borealis (Baumann and Kondratieff). 4. Our results indicate that aquatic insect assemblages in relict glaciated subalpine headwaters were strongly differentiated among stream segment types. These results illustrate the contribution of headwaters to riverine biodiversity and emphasise the importance of these habitats for monitoring biotic responses to climate change. Monitoring biotic assemblages in high-elevation headwaters is needed to prevent the potential loss of unique and sensitive biota.

  7. Aquatic insect emergence from headwater streams flowing through regeneration and mature forests in western Oregon

    Science.gov (United States)

    Robert Progar; Andrew R. Moldenke

    2009-01-01

    We examined the effect of canopy cover on adult aquatic insect emergence by collecting bi-weekly samples from twelve headwater stream reaches flowing either under a mature conifer canopy or streams flowing through ten-year-old regeneration in western Oregon from February to November 1997. Density and biomass generally followed a bimodal curve with peaks during early...

  8. Effects of watershed history on dissolved organic matter characteristics in headwater streams

    Science.gov (United States)

    Youhei Yamashita; Brian D. Kloeppel; Jennifer Knoepp; Gregory L. Zausen; Rudolf Jaffe'

    2011-01-01

    Dissolved organic matter (DOM) is recognized as a major component in the global carbon cycle and is an important driver in aquatic ecosystem function. Climate, land use, and forest cover changes all impact stream DOM and alter biogeochemical cycles in terrestrial environments. We determined the temporal variation in DOM quantity and quality in headwater streams at a...

  9. Effects of Student-Induced Trampling on Aquatic Macroinvertebrates in Agricultural Headwater Streams

    Directory of Open Access Journals (Sweden)

    Jon P. Bossley

    2018-01-01

    Full Text Available Outdoor education (OE stream classes provide students with an opportunity to gain hands-on experience with sampling methods for evaluating stream water quality. Trampling by students as a result of stream classes may disrupt the substrate and negatively impact aquatic macroinvertebrates. The impact of student-induced trampling in headwaters as a result of stream classes on aquatic macroinvertebrates has not been evaluated. Our aim was to document the short-term macroinvertebrate responses to an experimental disturbance that simulated the impacts of trampling by students in riffles within small headwater streams. We measured hydrologic variables, visually estimated substrate composition and sampled aquatic macroinvertebrates within control and experimental riffles in three agricultural headwater streams in central Ohio one day prior to experimental disturbance, immediately after disturbance and one day after disturbance. Hydrologic variables and substrate type did not differ daily or between riffle types. Macroinvertebrate abundance, percentage of Ephemeroptera Plecoptera Trichoptera and percentage of Leuctridae increased after experimental disturbance, while diversity, evenness, percentage of clingers and non-metric multidimensional scaling (NMS axis 1 site scores declined after disturbance. Macroinvertebrate diversity, percent clingers and NMS axis 1 site scores were lower in experimental riffles than control riffles. None of the macroinvertebrate response variables exhibited a significant interaction effect of day × riffle type that is indicative of an effect of the experimental disturbance. Our results suggest the one-time use of an undisturbed riffle within an agricultural headwater stream for an OE stream class is not likely to impact aquatic macroinvertebrates.

  10. Long-term resource limitation reduces insect detritivore growth in a headwater stream

    Science.gov (United States)

    Brent R. Johnson; Wyatt F. Cross; J. Bruce Wallace

    2003-01-01

    We measured larval growth rates of 2 dominant stream detritivore groups to assess the mechanism underlying declines in invertebrate production following exclusion of terrestrial litter inputs to a forested headwater stream. Larval Tallaperla spp. (P1ecoptera:Peltoperlidae) were chosen as representative shredders and non-Tanypodinae Chironomidae (...

  11. Map-based prediction of organic carbon in headwater streams improved by downstream observations from the river outlet

    Science.gov (United States)

    Temnerud, J.; von Brömssen, C.; Fölster, J.; Buffam, I.; Andersson, J.-O.; Nyberg, L.; Bishop, K.

    2016-01-01

    In spite of the great abundance and ecological importance of headwater streams, managers are usually limited by a lack of information about water chemistry in these headwaters. In this study we test whether river outlet chemistry can be used as an additional source of information to improve the prediction of the chemistry of upstream headwaters (size interquartile range (IQR)) of headwater stream TOC for a given catchment, based on a large number of candidate variables including sub-catchment characteristics from GIS, and measured river chemistry at the catchment outlet. The best candidate variables from the PLS models were then used in hierarchical linear mixed models (MM) to model TOC in individual headwater streams. Three predictor variables were consistently selected for the MM calibration sets: (1) proportion of forested wetlands in the sub-catchment (positively correlated with headwater stream TOC), (2) proportion of lake surface cover in the sub-catchment (negatively correlated with headwater stream TOC), and (3) river outlet TOC (positively correlated with headwater stream TOC). Including river outlet TOC improved predictions, with 5-15 % lower prediction errors than when using map information alone. Thus, data on water chemistry measured at river outlets offer information which can complement GIS-based modelling of headwater stream chemistry.

  12. Impacts of fish farm pollution on ecosystem structure and function of tropical headwater streams

    International Nuclear Information System (INIS)

    Rosa, Rodrigo dos Santos; Aguiar, Anna Carolina Fornero; Boëchat, Iola Gonçalves; Gücker, Björn

    2013-01-01

    We investigated the impacts of effluent discharge from small flow-through fish farms on stream water characteristics, the benthic invertebrate community, whole-system nitrate uptake, and ecosystem metabolism of three tropical headwater streams in southeastern Brazil. Effluents were moderately, i.e. up to 20-fold enriched in particulate organic matter (POM) and inorganic nutrients in comparison to stream water at reference sites. Due to high dilution with stream water, effluent discharge resulted in up to 2.0-fold increases in stream water POM and up to 1.8-fold increases in inorganic nutrients only. Moderate impacts on the benthic invertebrate community were detected at one stream only. There was no consistent pattern of effluent impact on whole-stream nitrate uptake. Ecosystem metabolism, however, was clearly affected by effluent discharge. Stream reaches impacted by effluents exhibited significantly increased community respiration and primary productivity, stressing the importance of ecologically sound best management practices for small fish farms in the tropics. -- Highlights: ► Fish farm effluent discharge had moderate effects on stream water quality. ► Impacts on the benthic invertebrate community occurred at one stream. ► Whole-stream nitrate uptake showed no consistent impact pattern. ► Effluents caused considerable increases in stream ecosystem metabolism. ► Compliance with best management practices is important for small fish farms. -- Moderate water pollution by small fish farms caused considerable eutrophication responses in tropical headwater streams

  13. Large carbon dioxide fluxes from headwater boreal and sub-boreal streams.

    Science.gov (United States)

    Venkiteswaran, Jason J; Schiff, Sherry L; Wallin, Marcus B

    2014-01-01

    Half of the world's forest is in boreal and sub-boreal ecozones, containing large carbon stores and fluxes. Carbon lost from headwater streams in these forests is underestimated. We apply a simple stable carbon isotope idea for quantifying the CO2 loss from these small streams; it is based only on in-stream samples and integrates over a significant distance upstream. We demonstrate that conventional methods of determining CO2 loss from streams necessarily underestimate the CO2 loss with results from two catchments. Dissolved carbon export from headwater catchments is similar to CO2 loss from stream surfaces. Most of the CO2 originating in high CO2 groundwaters has been lost before typical in-stream sampling occurs. In the Harp Lake catchment in Canada, headwater streams account for 10% of catchment net CO2 uptake. In the Krycklan catchment in Sweden, this more than doubles the CO2 loss from the catchment. Thus, even when corrected for aquatic CO2 loss measured by conventional methods, boreal and sub-boreal forest carbon budgets currently overestimate carbon sequestration on the landscape.

  14. Decomposition of terrestrial resource subsidies in headwater streams: Does consumer diversity matter?

    Science.gov (United States)

    David Stoker; Amber J. Falkner; Kelly M. Murray; Ashley K. Lang; Thomas R. Barnum; Jeffrey Hepinstall-Cymerman; Michael J. Conroy; Robert J. Cooper; Catherine M. Pringle

    2017-01-01

    Resource subsidies and biodiversity are essential for maintaining community structure and ecosystem functioning, but the relative importance of consumer diversity and resource characteristics to decomposition remains unclear. Forested headwater streams are detritus-based systems, dependent on leaf litter inputs from adjacent riparian ecosystems, and...

  15. Thinning and riparian buffer configuration effects on down wood abundance in headwater streams in coniferous forests

    Science.gov (United States)

    Adrian Ares; Deanna H. Olson; Klaus J. Puettmann

    2013-01-01

    Down wood is associated with the function, structure, and diversity of riparian systems. Considerable knowledge has been generated regarding down wood stocks and dynamics in temperate forests, but there are few studies on effects of silvicultural practices and riparian buffer design on down wood, particularly in headwater streams. We analyzed interactive eff ects of...

  16. Diel turbidity cycles in a headwater stream: evidence of nocturnal bioturbation?

    OpenAIRE

    Cooper, Richard J.; Outram, Faye; Hiscock, Kevin M.

    2016-01-01

    Purpose: A small number of recent studies have linked daily cycles in stream turbidity to nocturnal bioturbation by aquatic fauna, principally crayfish, and demonstrated this process can significantly impact upon water quality under baseflow conditions. Adding to this limited body of research, we use high-resolution water quality monitoring data to investigate evidence of diel turbidity cycles in a lowland, headwater stream with a known signal crayfish (Pacifastacus leniusculus) population an...

  17. Hydrogeomorphic connectivity on roads crossing in rural headwaters and its effect on stream dynamics.

    Science.gov (United States)

    Thomaz, Edivaldo L; Peretto, Gustavo T

    2016-04-15

    Unpaved roads are ubiquitous features that have been transforming the landscape through human history. Unpaved roads affect the water and sediment pathways through a catchment and impacts the aquatic ecosystem. In this study, we describe the effect of unpaved road on the hydrogeomorphic connectivity at the rural headwater scale. Measurement was based on the stream crossing approach, i.e., road superimposing the drainage system. We installed a Parshall flume coupled with single-stage suspended sediment sampler at each stream crossing. In addition, we displayed our monitoring scheme with an upscaling perspective from second-order to third-order stream. We concluded that the road-stream coupling dramatically changed the stream dynamic. The increase of discharge caused by roads at the headwater was 50% larger compared to unaffected streams. Additionally, suspended sediment concentration enhancement at stream crossings ranged from to 413% at second-order streams to 145% at third-order streams. The landform characteristics associated with the road network produced an important hydrogeomorphic disruption in the landscape. As a result, the sediment filter function of the riparian zone was reduced dramatically. Therefore, we recommend that projects for aquatic system restoration or conservation in rural landscape consider the role of the road network on stream dynamics. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. A catchment scale evaluation of multiple stressor effects in headwater streams.

    Science.gov (United States)

    Rasmussen, Jes J; McKnight, Ursula S; Loinaz, Maria C; Thomsen, Nanna I; Olsson, Mikael E; Bjerg, Poul L; Binning, Philip J; Kronvang, Brian

    2013-01-01

    Mitigation activities to improve water quality and quantity in streams as well as stream management and restoration efforts are conducted in the European Union aiming to improve the chemical, physical and ecological status of streams. Headwater streams are often characterised by impairment of hydromorphological, chemical, and ecological conditions due to multiple anthropogenic impacts. However, they are generally disregarded as water bodies for mitigation activities in the European Water Framework Directive despite their importance for supporting a higher ecological quality in higher order streams. We studied 11 headwater streams in the Hove catchment in the Copenhagen region. All sites had substantial physical habitat and water quality impairments due to anthropogenic influence (intensive agriculture, urban settlements, contaminated sites and low base-flow due to water abstraction activities in the catchment). We aimed to identify the dominating anthropogenic stressors at the catchment scale causing ecological impairment of benthic macroinvertebrate communities and provide a rank-order of importance that could help in prioritising mitigation activities. We identified numerous chemical and hydromorphological impacts of which several were probably causing major ecological impairments, but we were unable to provide a robust rank-ordering of importance suggesting that targeted mitigation efforts on single anthropogenic stressors in the catchment are unlikely to have substantial effects on the ecological quality in these streams. The SPEcies At Risk (SPEAR) index explained most of the variability in the macroinvertebrate community structure, and notably, SPEAR index scores were often very low (<10% SPEAR abundance). An extensive re-sampling of a subset of the streams provided evidence that especially insecticides were probably essential contributors to the overall ecological impairment of these streams. Our results suggest that headwater streams should be considered in

  19. Headwater Stream Management Dichotomies: Local Amphibian Habitat vs. Downstream Fish Habitat

    Science.gov (United States)

    Jackson, C. R.

    2002-12-01

    Small headwater streams in mountainous areas of the Pacific Northwest often do not harbor fish populations because of low water depth and high gradients. Rather, these streams provide habitat for dense assemblages of stream-dwelling amphibians. A variety of management goals have been suggested for such streams such as encouraging large woody debris recruitment to assist in sediment trapping and valley floor formation, encouraging large woody debris recruitment to provide downstream wood when debris flows occur, providing continuous linear stream buffers within forest harvest areas to provide shade and bank stability, etc. A basic problem with analying the geomorphic or biotic benefits of any of these strategies is the lack of explicit management goals for such streams. Should managers strive to optimize downstream fish habitat, local amphibian habitat, or both? Through observational data and theoretical considerations, it will be shown that these biotic goals will lead to very different geomorphic management recommendations. For instance, woody debris greater than 60 cm diameter may assist in valley floor development, but it is likely to create subsurface channel flow of unknown value to amphibians. Trapping and retention of fine sediments within headwater streams may improve downstream spawning gravels, but degrades stream-dwelling amphibian habitat. In response to the need for descriptive information on habitat and channel morphology specific to small, non-fish-bearing streams in the Pacific Northwest, morphologies and wood frequencies in forty-two first- and second-order forested streams less than four meters wide were surveyed. Frequencies and size distributions of woody debris were compared between small streams and larger fish-bearing streams as well as between second-growth and virgin timber streams. Statistical models were developed to explore dominant factors affecting channel morphology and habitat. Findings suggest geomorphological relationships

  20. Groundwater data improve modelling of headwater stream CO2 outgassing with a stable DIC isotope approach

    Directory of Open Access Journals (Sweden)

    A. Marx

    2018-05-01

    Full Text Available A large portion of terrestrially derived carbon outgasses as carbon dioxide (CO2 from streams and rivers to the atmosphere. Particularly, the amount of CO2 outgassing from small headwater streams is highly uncertain. Conservative estimates suggest that they contribute 36 % (i.e. 0.93 petagrams (Pg C yr−1 of total CO2 outgassing from all fluvial ecosystems on the globe. In this study, stream pCO2, dissolved inorganic carbon (DIC, and δ13CDIC data were used to determine CO2 outgassing from an acidic headwater stream in the Uhlířská catchment (Czech Republic. This stream drains a catchment with silicate bedrock. The applied stable isotope model is based on the principle that the 13C ∕ 12C ratio of its sources and the intensity of CO2 outgassing control the isotope ratio of DIC in stream water. It avoids the use of the gas transfer velocity parameter (k, which is highly variable and mostly difficult to constrain. Model results indicate that CO2 outgassing contributed more than 80 % to the annual stream inorganic carbon loss in the Uhlířská catchment. This translated to a CO2 outgassing rate from the stream of 34.9 kg C m−2 yr−1 when normalised to the stream surface area. Large temporal variations with maximum values shortly before spring snowmelt and in summer emphasise the need for investigations at higher temporal resolution. We improved the model uncertainty by incorporating groundwater data to better constrain the isotope compositions of initial DIC. Due to the large global abundance of acidic, humic-rich headwaters, we underline the importance of this integral approach for global applications.

  1. Groundwater data improve modelling of headwater stream CO2 outgassing with a stable DIC isotope approach

    Science.gov (United States)

    Marx, Anne; Conrad, Marcus; Aizinger, Vadym; Prechtel, Alexander; van Geldern, Robert; Barth, Johannes A. C.

    2018-05-01

    A large portion of terrestrially derived carbon outgasses as carbon dioxide (CO2) from streams and rivers to the atmosphere. Particularly, the amount of CO2 outgassing from small headwater streams is highly uncertain. Conservative estimates suggest that they contribute 36 % (i.e. 0.93 petagrams (Pg) C yr-1) of total CO2 outgassing from all fluvial ecosystems on the globe. In this study, stream pCO2, dissolved inorganic carbon (DIC), and δ13CDIC data were used to determine CO2 outgassing from an acidic headwater stream in the Uhlířská catchment (Czech Republic). This stream drains a catchment with silicate bedrock. The applied stable isotope model is based on the principle that the 13C / 12C ratio of its sources and the intensity of CO2 outgassing control the isotope ratio of DIC in stream water. It avoids the use of the gas transfer velocity parameter (k), which is highly variable and mostly difficult to constrain. Model results indicate that CO2 outgassing contributed more than 80 % to the annual stream inorganic carbon loss in the Uhlířská catchment. This translated to a CO2 outgassing rate from the stream of 34.9 kg C m-2 yr-1 when normalised to the stream surface area. Large temporal variations with maximum values shortly before spring snowmelt and in summer emphasise the need for investigations at higher temporal resolution. We improved the model uncertainty by incorporating groundwater data to better constrain the isotope compositions of initial DIC. Due to the large global abundance of acidic, humic-rich headwaters, we underline the importance of this integral approach for global applications.

  2. An ecohydrological stream type cassification of intermittent and ephemeral streams in the Southwestern United States 2397

    Science.gov (United States)

    Ephemeral and intermittent streams are the predominant fluvial forms in arid and semi-arid environments. Various studies have shown biological and habitat diversity in these lands to be considerably higher along stream corridors in comparison to adjacent uplands, yet knowledge of how these streams f...

  3. Decoupling of dissolved organic matter patterns between stream and riparian groundwater in a headwater forested catchment

    Science.gov (United States)

    Bernal, Susana; Lupon, Anna; Catalán, Núria; Castelar, Sara; Martí, Eugènia

    2018-03-01

    Streams are important sources of carbon to the atmosphere, though knowing whether they merely outgas terrestrially derived carbon dioxide or mineralize terrestrial inputs of dissolved organic matter (DOM) is still a big challenge in ecology. The objective of this study was to investigate the influence of riparian groundwater (GW) and in-stream processes on the temporal pattern of stream DOM concentrations and quality in a forested headwater stream, and whether this influence differed between the leaf litter fall (LLF) period and the remaining part of the year (non-LLF). The spectroscopic indexes (fluorescence index, biological index, humification index, and parallel factor analysis components) indicated that DOM had an eminently protein-like character and was most likely originated from microbial sources and recent biological activity in both stream water and riparian GW. However, paired samples of stream water and riparian GW showed that dissolved organic carbon (DOC) and nitrogen (DON) concentrations as well as the spectroscopic character of DOM differed between the two compartments throughout the year. A simple mass balance approach indicated that in-stream processes along the reach contributed to reducing DOC and DON fluxes by 50 and 30 %, respectively. Further, in-stream DOC and DON uptakes were unrelated to each other, suggesting that these two compounds underwent different biogeochemical pathways. During the LLF period, stream DOC and DOC : DON ratios were higher than during the non-LLF period, and spectroscopic indexes suggested a major influence of terrestrial vegetation on stream DOM. Our study highlights that stream DOM is not merely a reflection of riparian GW entering the stream and that headwater streams have the capacity to internally produce, transform, and consume DOM.

  4. Headwater fish population responses to planting grass filter strips adjacent to channelized agricultural headwater streams

    Science.gov (United States)

    Grass filter strips are a widely used conservation practice in the Midwestern United States for reducing nutrient, pesticide, and sediment inputs into agricultural streams. Only a limited amount of information is available on the ecological effects of planting grass filter strips adjacent to channe...

  5. Resilience of imperilled headwater stream fish to an unpredictable high-magnitude flood

    Directory of Open Access Journals (Sweden)

    Bruce R. Ellender

    2015-05-01

    Full Text Available Headwater stream fish communities are increasingly becoming isolated in headwater refugia that are often cut off from other metapopulations within a river network as a result of nonnative fish invasions, pollution, water abstraction and habitat degradation downstream. This range restriction and isolation therefore makes them vulnerable to extinction. Understanding threats to isolated fish populations is consequently important for their conservation. Following a base-flow survey, a high-magnitude flood (peak flow of 1245 m-3s-1 provided an opportunity to investigate the response of endangered Eastern Cape redfin Pseudobarbus afer populations to a natural disturbance in the Waterkloof and Fernkloof streams, two relatively pristine headwater tributaries of the Swartkops River system within the Groendal Wilderness Area, Eastern Cape Province, South Africa. Pseudobarbus afer had limited distributions, occupying 3 km in both the Fernkloof and Waterkloof streams. Fish population assessments before and after the flood event indicated that there were no longitudinal trends in P. afer abundance before or after the flood, but overall abundance post-flooding in the Fernkloof stream was higher. There were no noticeable changes in P. afer size structure pre- and post-flood. Pseudobarbus afer showed resilience to a major flooding event most likely related to evolution in river systems characterised by environmental stochasticity. Conservation implications: This research provides insight into the population level responses of native headwater stream fishes to unpredictable natural disturbance. Of particular relevance is information on their ability to withstand natural disturbances, which provides novel information essential for their conservation and management especially as these fishes are already impacted by multiple anthropogenic stressors.

  6. Biodiversity management approaches for stream-riparian areas: perspectives for Pacific Northwest headwater forests, microclimates, and amphibians.

    Science.gov (United States)

    D.H. Olson; P.D. Anderson; C.A. Frissell; H.H. Welsh; D.F. Bradford

    2007-01-01

    New science insights are redefining stream riparian zones, particularly relative to headwaters, microclimate conditions, and fauna such as amphibians. We synthesize data on these topics, and propose management approaches to target sensitive biota at reach to landscape scales.

  7. Determination of mercury evasion in a contaminated headwater stream.

    Science.gov (United States)

    Maprani, Antu C; Al, Tom A; Macquarrie, Kerry T; Dalziel, John A; Shaw, Sean A; Yeats, Phillip A

    2005-03-15

    Evasion from first- and second-order streams in a watershed may be a significant factor in the atmospheric recycling of volatile pollutants such as mercury; however, methods developed for the determination of Hg evasion rates from larger water bodies are not expected to provide satisfactory results in highly turbulent and morphologically complex first- and second-order streams. A new method for determining the Hg evasion rates from these streams, involving laboratory gas-indexing experiments and field tracer tests, was developed in this study to estimate the evasion rate of Hg from Gossan Creek, a first-order stream in the Upsalquitch River watershed in northern New Brunswick, Canada. Gossan Creek receives Hg-contaminated groundwater discharge from a gold mine tailings pile. Laboratory gas-indexing experiments provided the ratio of gas-exchange coefficients for zero-valent Hg to propane (tracer gas) of 0.81+/-0.16, suggesting that the evasion mechanism in highly turbulent systems can be described by the surface renewal model with an additional component of enhanced gas evasion probably related to the formation of bubbles. Deliberate field tracer tests with propane and chloride tracers were found to be a reliable and practical method for the determination of gas-exchange coefficients for small streams. Estimation of Hg evasion from the first 1 km of Gossan Creek indicates that about 6.4 kg of Hg per year is entering the atmosphere, which is a significant fraction of the regional sources of Hg to the atmosphere.

  8. Channel water balance and exchange with subsurface flow along a mountain headwater stream in Montana, United States

    Science.gov (United States)

    R.A. Payn; M.N. Gooseff; B.L. McGlynn; K.E. Bencala; S.M. Wondzell

    2009-01-01

    Channel water balances of contiguous reaches along streams represent a poorly understood scale of stream-subsurface interaction. We measured reach water balances along a headwater stream in Montana, United States, during summer base flow recessions. Reach water balances were estimated from series of tracer tests in 13 consecutive reaches delineated evenly along a 2.6-...

  9. Governance, legislation and protection of intermittent rivers and ephemeral streams

    Science.gov (United States)

    Institutions and processes governing the conveyance and control of water have a long history. In this chapter, we discuss the extent to which water governance systems consider the management of intermittent rivers and ephemeral streams (IRES) and identify where research could inf...

  10. Biomonitoring of intermittent rivers and ephemeral streams in Europe

    NARCIS (Netherlands)

    Stubbington, Rachel; Chadd, Richard; Cid, Núria; Csabai, Zoltán; Miliša, Marko; Morais, Manuela; Munné, Antoni; Pařil, Petr; Pešić, Vladimir; Tziortzis, Iakovos; Verdonschot, Ralf C.M.; Datry, Thibault

    2018-01-01

    Intermittent rivers and ephemeral streams (IRES) are common across Europe and dominate some Mediterranean river networks. In all climate zones, IRES support high biodiversity and provide ecosystem services. As dynamic ecosystems that transition between flowing, pool, and dry states, IRES are

  11. Low prevalence of chytrid fungus (Batrachochytrium dendrobatidis) in amphibians of U.S. headwater streams

    Science.gov (United States)

    Hossack, Blake R.; Adams, Michael J.; Campbell Grant, Evan H.; Pearl, Chistopher A.; Bettaso, James B.; Barichivich, William J.; Lowe, Winsor H.; True, Kimberly; Ware, Joy L.; Corn, Paul Stephen

    2010-01-01

    Many declines of amphibian populations have been associated with chytridiomycosis, a disease caused by the aquatic fungus Batrachochytrium dendrobatidis (Bd). Despite the relatively high prevalence of chytridiomycosis in stream amphibians globally, most surveys in North America have focused primarily on wetland-associated species, which are frequently infected. To better understand the distribution and prevalence of Bd in headwater amphibian communities, we sampled 452 tailed frogs (Ascaphus truei and Ascaphus montanus) and 304 stream salamanders (seven species in the Dicamptodontidae and Plethodontidae) for Bd in 38, first- to third-order streams in five montane areas across the United States. We tested for presence of Bd by using PCR on skin swabs from salamanders and metamorphosed tailed frogs or the oral disc of frog larvae. We detected Bd on only seven individuals (0.93%) in four streams. Based on our study and results from five other studies that have sampled headwater- or seep-associated amphibians in the United States, Bd has been detected on only 3% of 1,322 individuals from 21 species. These results differ strongly from surveys in Central America and Australia, where Bd is more prevalent on stream-breeding species, as well as results from wetland-associated anurans in the same regions of the United States that we sampled. Differences in the prevalence of Bd between stream- and wetland-associated amphibians in the United States may be related to species-specific variation in susceptibility to chytridiomycosis or habitat differences.

  12. Early ecosystem responses to watershed restoration along a headwater stream

    DEFF Research Database (Denmark)

    Kallenbach, Emilie M.F.; Sand-Jensen, Kaj; Morsing, Jonas

    2018-01-01

    Along many streams, natural riparian vegetation has been replaced by agricultural fields or plantations resulting in ecosystem alterations due to changes of the interactions across the land-water ecotone. We studied the effect of restoration interventions by removing a dense spruce plantation in ...

  13. Heed the head: buffer benefits along headwater streams

    Science.gov (United States)

    Rhonda Mazza; Deanna (Dede) Olson

    2015-01-01

    Since the Northwest Forest Plan implemented riparian buffers along non-fish bearing streams in 1994, there have been questions about how wide those buffers need to be to protect aquatic and riparian resources from upland forest management activities. The Density Management and Riparian Buffer Study of western Oregon, also initiated in 1994, examines the effects of...

  14. Effects of Large Wood on River-Floodplain Connectivity in a Headwater Appalachian Stream

    Science.gov (United States)

    Keys, T.; Govenor, H.; Jones, C. N.; Hession, W. C.; Scott, D.; Hester, E. T.

    2017-12-01

    Large wood (LW) plays an important, yet often undervalued role in stream ecosystems. Traditionally, LW has been removed from streams for aesthetic, navigational, and flood mitigation purposes. However, extensive research over the last three decades has directly linked LW to critical ecosystem functions including habitat provisioning, stream geomorphic stability, and water quality improvements; and as such, LW has increasingly been implemented in stream restoration activities. One of the proposed benefits to this restoration approach is that LW increases river-floodplain connectivity, potentially decreasing downstream flood peaks and improving water quality. Here, we conducted two experiential floods (i.e., one with and one without LW) in a headwater, agricultural stream to explore the effect of LW on river-floodplain connectivity and resulting hydrodynamic processes. During each flood, we released an equal amount of water to the stream channel, measured stream discharge at upstream and downstream boundaries, and measured inundation depth at multiple locations across the floodplain. We then utilized a 2-dimensional hydrodynamic model (HEC-RAS) to simulate floodplain hydrodynamics. We first calibrated the model using observations from the two experimental floods. Then, we utilized the calibrated model to evaluate differing LW placement strategies and effects under various flow conditions. Results show that the addition of LW to the channel decreased channel velocity and increased inundation extent, inundation depth, and floodplain velocity. Differential placement of LW along the stream impacted the levels of floodplain discharge, primarily due to the geomorphic characteristics of the stream. Finally, we examined the effects of LW on floodplain hydrodynamics across a synthetic flow record, and found that the magnitude of river-floodplain connectivity decreased as recurrence interval increased, with limited impacts on storm events with a recurrence interval of 25 years

  15. An evaluation of the effects of acid rain on low conductivity headwater streams in Pennsylvania

    Science.gov (United States)

    Ritter, John R.; Brown, Ann E.

    1981-01-01

    Analyses of water collected at 32 sites on headwater streams in Pennsylvania during low-flow conditions in 1970-80 were compared to pre-1971 data to evaluate whether acid rain had changed the chemistry of the streams in the previous decade. Most pH, alkalinity, and sulfate values of the samples collected in 1970-80 fell within the ranges of values for samples collected before 1971. The limited data indicate, however, that pH may have increased and alkalinity and sulfate may have decreased with time.

  16. Transport and fate of nitrate in headwater agricultural streams in Illinois.

    Science.gov (United States)

    Royer, Todd V; Tank, Jennifer L; David, Mark B

    2004-01-01

    Nitrogen inputs to the Gulf of Mexico have increased during recent decades and agricultural regions in the upper Midwest, such as those in Illinois, are a major source of N to the Mississippi River. How strongly denitrification affects the transport of nitrate (NO(3)-N) in Illinois streams has not been directly assessed. We used the nutrient spiraling model to assess the role of in-stream denitrification in affecting the concentration and downstream transport of NO(3)-N in five headwater streams in agricultural areas of east-central Illinois. Denitrification in stream sediments was measured approximately monthly from April 2001 through January 2002. Denitrification rates tended to be high (up to 15 mg N m(-2) h(-1)), but the concentration of NO(3)-N in the streams was also high (>7 mg N L(-1)). Uptake velocities for NO(3)-N (uptake rate/concentration) were lower than reported for undisturbed streams, indicating that denitrification was not an efficient N sink relative to the concentration of NO(3)-N in the water column. Denitrification uptake lengths (the average distance NO(3)-N travels before being denitrified) were long and indicated that denitrification in the streambed did not affect the transport of NO(3)-N. Loss rates for NO(3)-N in the streams were <5% d(-1) except during periods of low discharge and low NO(3)-N concentration, which occurred only in late summer and early autumn. Annually, most NO(3)-N in these headwater sites appeared to be exported to downstream water bodies rather than denitrified, suggesting previous estimates of N losses through in-stream denitrification may have been overestimated.

  17. Sensitivity of intermittent streams to climate variations in the USA

    Science.gov (United States)

    Eng, Kenny; Wolock, David M.; Dettinger, Mike

    2015-01-01

    There is a great deal of interest in the literature on streamflow changes caused by climate change because of the potential negative effects on aquatic biota and water supplies. Most previous studies have primarily focused on perennial streams, and there have been only a few studies examining the effect of climate variability on intermittent streams. Our objectives in this study were to (1) identify regions of similar zero-flow behavior, and (2) evaluate the sensitivity of intermittent streams to historical variability in climate in the United States. This study was carried out at 265 intermittent streams by evaluating: (1) correlations among time series of flow metrics (number of zero-flow events, the average of the central 50% and largest 10% of flows) with climate (magnitudes, durations and intensity), and (2) decadal changes in the seasonality and long-term trends of these flow metrics. Results identified five distinct seasonality patterns in the zero-flow events. In addition, strong associations between the low-flow metrics and historical changes in climate were found. The decadal analysis suggested no significant seasonal shifts or decade-to-decade trends in the low-flow metrics. The lack of trends or changes in seasonality is likely due to unchanged long-term patterns in precipitation over the time period examined.

  18. Variation in summer nitrogen and phosphorus uptake among Siberian headwater streams

    Directory of Open Access Journals (Sweden)

    John D. Schade

    2016-06-01

    Full Text Available Arctic streams are likely to receive increased inputs of dissolved nutrients and organic matter from thawing permafrost as climate warms. Documenting how Arctic streams process inorganic nutrients is necessary to understand mechanisms that regulate watershed fluxes of permafrost-derived materials to downstream ecosystems. We report on summer nitrogen (N and phosphorus (P uptake in streams draining upland soils from the Pleistocene, and lowland floodplain soils from the Holocene, in Siberia's Kolyma River watershed. Uptake of N and P differed between upland and floodplain streams, suggesting topographic variation in nutrient limitation. In floodplain streams, P uptake rate and uptake velocity were higher than N, while upland streams had similar values for all N and P uptake metrics. Phosphorus uptake velocity and size of the transient hydrologic storage zone were negatively related across all study streams, indicating strong influence of hydrologic processes on nutrient fluxes. Physical sorption of P was higher in floodplain stream sediments relative to upland stream sediments, suggesting more physically driven uptake in floodplain streams and higher biological activity in upland streams. Overall, these results demonstrate that high-latitude headwater streams actively retain N and P during summer base flows; however, floodplain and upland streams varied substantially in N and P uptake and may respond differently to inorganic nutrient and organic matter inputs. Our results highlight the need for a comprehensive assessment of N and P uptake and retention in Arctic streams in order to fully understand the impact of permafrost-derived materials on ecosystem processes, and their fate in continental drainage networks.

  19. Biotic Responses of Headwater Streams to Geophysical Alteration and Disturbance Related to Climate Change

    Science.gov (United States)

    Gresswell, R. E.; Sedell, E. R.; Cannon, S.; Hostetler, S. W.; Williams, J. E.; Haak, A. L.; Kershner, J. L.

    2009-12-01

    Climate change will potentially alter physical habitat availability for trout species (both native and nonnative) in the western USA, and ultimately affect population distribution and abundance in watersheds across the region. To understand the biological consequences of habitat alteration associated with climate change, we have developed models linking contemporary patterns of occurrence and abundance to geomorphic variables (e.g., aspect, elevation, and slope) and stream conditions derived from the habitat (e.g., temperature, discharge, and flood regimes). Because headwater streams may be especially susceptible to catastrophic disturbances in the form of debris flow torrents that have the potential to radically alter the physical structure of channels and sometimes extirpate local fish populations, we are focusing fine-scale spatial analyses in the high elevation systems. Risks of such disturbances increase exponentially in landscapes that have experienced recent wildfires when high-intensity precipitation or runoff events occur. Although predicting the timing, extent, and severity of future wildfires or subsequent precipitation and runoff events is difficult, it is possible to identify channels within stream networks that may be prone to debris flows. These channels can be identified using models based on characteristic storm and burn scenarios and geographic information describing topographic, soil, and vegetation characteristics. At-risk channels are being mapped throughout the stream networks within the study areas in the headwaters of the Colorado River to provide information about the potential for catastrophic population disturbance in response to variety of wildfire and post-wildfire storm scenarios.

  20. Similarities and differences in dissolved organic matter response in two headwater streams under contrasted hydro-climatic regimes

    Science.gov (United States)

    Butturini, Andrea; Guarch, Alba; Battin, Tom

    2017-04-01

    Dissolved organic matter (DOM) concentration and properties in headwater streams are strongly shaped by hydrology. Besides the direct relationship with storms and high flows, seasonal variability of base flow also influences DOM variability. This study focuses on identifying the singularities and similarities in DOM - discharge relationships between an intermittent Mediterranean stream (Fuirosos) and a perennial Alpine stream (Oberer Seebach). Oberer Seebach had a higher discharge mean, but Fuirosos had a higher variability in flow and in magnitude of storm events. During three years we performed an intensive sampling that allows us to satisfactorily capture abrupt and extreme storms. We analysed dissolved organic carbon concentration (DOC) and optical properties of DOM and we calculated the specific ultraviolet absorbance (SUVA), the spectral slopes ratio (SR), the fluorescence index (FI), the biological index (BIX) and the humification index (HIX). DOM in Fuirosos was significantly more concentrated than in Oberer Seebach, and more terrigenous (lower FI), more degraded (lower BIX), more aromatic (higher SUVA) and more humificated (higher HIX). Most of the DOM properties showed a clear relationship with discharge and the sign of the global response was identical in both streams. However, discharge was a more robust predictor of DOM variability in Oberer Seebach than in Fuirosos. In fact, low flow and rewetting periods in Fuirosos introduced considerable dispersion in the relationship. During snowmelt in Oberer Seebach the sensitivity to discharge also decreased (DOC and BIX) or disappeared (SR, FI and HIX). The magnitude of the storm events (DQ) in Fuirosos significantly drove the changes in DOC, FI, BIX and SUVA. This suggests that the flushing/dilution patterns were essentially associated to the occurrence of storm episodes in Fuirosos. In contrast, in Oberer Seebach all DOM qualitative properties were unrelated to DQ and it significantly explained only the

  1. Riparian forest buffers mitigate the effects of deforestation on fish assemblages in tropical headwater streams.

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    Lorion, Christopher M; Kennedy, Brian P

    2009-03-01

    Riparian forest buffers may play a critical role in moderating the impacts of deforestation on tropical stream ecosystems, but very few studies have examined the ecological effects of riparian buffers in the tropics. To test the hypothesis that riparian forest buffers can reduce the impacts of deforestation on tropical stream biota, we sampled fish assemblages in lowland headwater streams in southeastern Costa Rica representing three different treatments: (1) forested reference stream reaches, (2) stream reaches adjacent to pasture with a riparian forest buffer averaging at least 15 m in width on each bank, and (3) stream reaches adjacent to pasture without a riparian forest buffer. Land cover upstream from the study reaches was dominated by forest at all of the sites, allowing us to isolate the reach-scale effects of the three study treatments. Fish density was significantly higher in pasture reaches than in forest and forest buffer reaches, mostly due to an increase in herbivore-detritivores, but fish biomass did not differ among reach types. Fish species richness was also higher in pasture reaches than in forested reference reaches, while forest buffer reaches were intermediate. Overall, the taxonomic and trophic structure of fish assemblages in forest and forest buffer reaches was very similar, while assemblages in pasture reaches were quite distinct. These patterns were persistent across three sampling periods during our 15-month study. Differences in stream ecosystem conditions between pasture reaches and forested sites, including higher stream temperatures, reduced fruit and seed inputs, and a trend toward increased periphyton abundance, appeared to favor fish species normally found in larger streams and facilitate a native invasion process. Forest buffer reaches, in contrast, had stream temperatures and allochthonous inputs more similar to forested streams. Our results illustrate the importance of riparian areas to stream ecosystem integrity in the tropics

  2. Hydrogeomorphic linkages of sediment transport in headwater streams, Maybeso Experimental Forest, southeast Alaska

    Science.gov (United States)

    Gomi, Takashi; Sidle, Roy C.; Swanston, Douglas N.

    2004-03-01

    Hydrogemorphic linkages related to sediment transport in headwater streams following basin wide clear-cut logging on Prince of Wales Island, southeast Alaska, were investigated. Landslides and debris flows transported sediment and woody debris in headwater tributaries in 1961, 1979, and 1993. Widespread landsliding in 1961 and 1993 was triggered by rainstorms with recurrence intervals (24 h precipitation) of 7.0 years and 4.2 years respectively. Occurrence, distribution, and downstream effects of these mass movements were controlled by landform characteristics such as channel gradient and valley configuration. Landslides and channelized debris flows created exposed bedrock reaches, log jams, fans, and abandoned channels. The terminus of the deposits did not enter main channels because debris flows spread and thinned on the unconfined bottom of the U-shaped glaciated valley. Chronic sediment input to channels included surface erosion of exposed till (rain splash, sheet erosion, and freeze-thaw action) and bank failures. Bedload sediment transport in a channel impacted by 1993 landslides and debris flows was two to ten times greater and relatively finer compared with bedload transport in a young alder riparian channel that had last experienced a landslide and debris flow in 1961. Sediment transport and storage were influenced by regeneration of riparian vegetation, storage behind recruited woody debris, development of a streambed armour layer, and the decoupling of hillslopes and channels. Both spatial and temporal variations of sediment movement and riparian condition are important factors in understanding material transport within headwaters and through channel networks.

  3. Quantifying spatial scaling patterns and their local and regional correlates in headwater streams: implications for resilience

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    Emma Göthe

    2014-09-01

    Full Text Available The distribution of functional traits within and across spatiotemporal scales has been used to quantify and infer the relative resilience across ecosystems. We use explicit spatial modeling to evaluate within- and cross-scale redundancy in headwater streams, an ecosystem type with a hierarchical and dendritic network structure. We assessed the cross-scale distribution of functional feeding groups of benthic invertebrates in Swedish headwater streams during two seasons. We evaluated functional metrics, i.e., Shannon diversity, richness, and evenness, and the degree of redundancy within and across modeled spatial scales for individual feeding groups. We also estimated the correlates of environmental versus spatial factors of both functional composition and the taxonomic composition of functional groups for each spatial scale identified. Measures of functional diversity and within-scale redundancy of functions were similar during both seasons, but both within- and cross-scale redundancy were low. This apparent low redundancy was partly attributable to a few dominant taxa explaining the spatial models. However, rare taxa with stochastic spatial distributions might provide additional information and should therefore be considered explicitly for complementing future resilience assessments. Otherwise, resilience may be underestimated. Finally, both environmental and spatial factors correlated with the scale-specific functional and taxonomic composition. This finding suggests that resilience in stream networks emerges as a function of not only local conditions but also regional factors such as habitat connectivity and invertebrate dispersal.

  4. Quantifying spatial scaling patterns and their local and regional correlates in headwater streams: Implications for resilience

    Science.gov (United States)

    Gothe, Emma; Sandin, Leonard; Allen, Craig R.; Angeler, David G.

    2014-01-01

    The distribution of functional traits within and across spatiotemporal scales has been used to quantify and infer the relative resilience across ecosystems. We use explicit spatial modeling to evaluate within- and cross-scale redundancy in headwater streams, an ecosystem type with a hierarchical and dendritic network structure. We assessed the cross-scale distribution of functional feeding groups of benthic invertebrates in Swedish headwater streams during two seasons. We evaluated functional metrics, i.e., Shannon diversity, richness, and evenness, and the degree of redundancy within and across modeled spatial scales for individual feeding groups. We also estimated the correlates of environmental versus spatial factors of both functional composition and the taxonomic composition of functional groups for each spatial scale identified. Measures of functional diversity and within-scale redundancy of functions were similar during both seasons, but both within- and cross-scale redundancy were low. This apparent low redundancy was partly attributable to a few dominant taxa explaining the spatial models. However, rare taxa with stochastic spatial distributions might provide additional information and should therefore be considered explicitly for complementing future resilience assessments. Otherwise, resilience may be underestimated. Finally, both environmental and spatial factors correlated with the scale-specific functional and taxonomic composition. This finding suggests that resilience in stream networks emerges as a function of not only local conditions but also regional factors such as habitat connectivity and invertebrate dispersal.

  5. Stream Ammonium Uptake Across Scales in Headwater Catchments of a Tropical Rainforest, Luquillo Mountains, Puerto Rico

    Science.gov (United States)

    Brereton, R. L.; McDowell, W. H.; Wymore, A.

    2015-12-01

    Many tropical forest streams export high amounts of nitrogen relative to streams draining undisturbed watersheds of other biomes. With their low DOC concentrations and high rates of respiration, headwater streams in the Luquillo Mountains have been previously characterized as energy-limited, suggesting that NH4+ uptake is dominated not by N demand but by energy demand. In the Rio Icacos watershed, high concentrations of NH4+ (>1 mg N/L) are found in groundwater adjacent to the streams, making high inputs of NH4+ to the stream channel via groundwater seepage likely. Stream nutrient spiraling metrics can be used to quantify uptake and retention rates of specific nutrients, and can be measured by solute additions. Tracer Additions for Spiraling Curve Characterization (TASCC) is a recently developed method (Covino et al. 2010) for quantifying nutrient uptake with a single slug addition of nutrient and conservative tracer. Here we present NH4+ uptake metrics from TASCC additions in three Luquillo streams of different sizes, ranging from 2nd to 4th order: the Rio Icacos, a larger, 3rd order tributary and a smaller 2nd order tributary. Background NH4+ concentrations vary by up to an order of magnitude, with highest concentrations (27 μg N/L) found in the smaller tributary. Background DOC concentrations are uniformly low and show no difference between the three streams (500-600 μg C/L). The smaller tributary has the shortest uptake length (155 m) and highest uptake velocity (2.9 mm/min) of the three streams. Unexpectedly, the Rio Icacos has a higher uptake velocity (1.7 mm/min) than the larger tributary (1.0 mm/min), despite having an uptake length more than double (1400 m) that of the larger tributary (596 m). Overall, NH4+ uptake is substantial in all three streams and varies with background concentrations, not stream size.

  6. Physical, chemical, and biological characteristics of selected headwater streams along the Allegheny Front, Blair County, Pennsylvania, July 2011–September 2013

    Science.gov (United States)

    Low, Dennis J.; Brightbill, Robin A.; Eggleston, Heather L.; Chaplin, Jeffrey J.

    2016-02-29

    The Altoona Water Authority (AWA) obtains all of its water supply from headwater streams that drain western Blair County, an area underlain in part by black shale of the Marcellus Formation. Development of the shale-gas reservoirs will require new access roads, stream crossing, drill-pad construction, and pipeline installation, activities that have the potential to alter existing stream channel morphology, increase runoff and sediment supply, alter streamwater chemistry, and affect aquatic habitat. The U.S. Geological Survey, in cooperation with Altoona Water Authority and Blair County Conservation District, investigated the water quality of 12 headwater streams and biotic health of 10 headwater streams.

  7. Future ecological studies of Brazilian headwater streams under global-changes

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    Marcos Callisto

    Full Text Available This paper results from discussions triggered during the "Stream Ecology Symposium" that took place at the XIII Congress of the Brazilian Society of Limnology in September of 2011 in Natal, Brazil. Based on our experiences, we have raised several questions regarding ecological studies of headwater streams facing threats under global-changes and proposed numerous subjects to be addressed in future studies in Brazil. These studies deal with the necessity of knowing species biology and the elaboration of models to assess changes (which implies the availability of time-series or large-scale data sets; the ecology of riparian zones and the interchange of materials and energy across the land-water boundaries; forest conversions and standardized sampling strategies and data treatment to assess global change.

  8. Assessing mercury exposure and effects to American dippers in headwater streams near mining sites.

    Science.gov (United States)

    Henny, Charles J; Kaiser, James L; Packard, Heidi A; Grove, Robert A; Taft, Michael R

    2005-10-01

    To evaluate mercury (Hg) exposure and possible adverse effects of Hg on American dipper (Cinclus mexicanus) reproduction, we collected eggs and nestling feathers and the larval/nymph form of three Orders of aquatic macroinvertebrates (Ephemeroptera, Plecoptera and Trichoptera = EPT) important in their diet from three major headwater tributaries of the upper Willamette River, Oregon in 2002. The Coast Fork Willamette River is contaminated with Hg due to historical cinnabar (HgS) mining at the Black Butte Mine; the Row River is affected by past gold-mining operations located within the Bohemia Mining District, where Hg was used in the amalgamation process to recover gold; and the Middle Fork Willamette River is the reference area with no known mining. Methyl mercury (MeHg) concentrations (geometric mean) in composite EPT larvae (111.9 ng/g dry weight [dw] or 19.8 ng/g wet weight [ww]), dipper eggs (38.5 ng/g ww) and nestling feathers (1158 ng/g ww) collected from the Coast Fork Willamette were significantly higher than MeHg concentrations in EPT and dipper samples from other streams. Total mercury (THg) concentrations in surface sediments along the same Hg-impacted streams were investigated by others in 1999 (Row River tributaries) and 2002 (Coast Fork). The reported sediment THg concentrations paralleled our biological findings. Dipper breeding territories at higher elevations had fewer second clutches; however, dipper reproductive success along all streams (including the lower elevation and most Hg-contaminated Coast Fork), was judged excellent compared to other studies reviewed. Furthermore, MeHg concentrations in EPT samples from this study were well below dietary concentrations in other aquatic bird species, such as loons and ducks, reported to cause Hg-related reproductive problems. Our data suggest that either dipper feathers or EPT composites used to project MeHg concentrations in dipper feathers (with biomagnification factor of 10-20x) may be used, but with

  9. Effect of residential development on stream phosphorus dynamics in headwater suburbanizing watersheds of southern Ontario, Canada.

    Science.gov (United States)

    Duval, Tim P

    2018-10-01

    Suburban landscapes are known to have degraded water quality relative to natural settings, including increased total phosphorus (TP) levels; however, the effect of subdivision construction activities on stream TP dynamics are less understood. This study measured TP and its constituents particulate, dissolved organic, and dissolved inorganic phosphorus (PP, DOP, and DIP, respectively) in two headwater streams of contrasting urbanization activity to examine whether the land-use conversion process itself contributed to TP concentrations and export. The nested watershed undergoing significant active residential community construction contained large areas of cleared former agricultural field and associated sediment mounds with elevated soil TP (~1000 mg kg -1 ), and twice as many stormwater management (SWM) ponds than the watershed with completed suburban communities. Daily stream sampling for six months revealed limited differences in TP between urbanized and urbanizing watersheds regardless of season or stream flow condition; however, the forms of TP varied significantly. The proportion of TP as DOP was consistently higher in the urbanizing stream relative to the urban stream, which was in line with significant decreases in DOP concentration as proportion of cleared former agricultural land decreased and density of SWM ponds increased. The DOP, and to a lesser extent DIP and PP, dynamics resulted in a 2.5× greater areal export of TP from a small watershed actively being suburbanized during the study period compared to the larger watershed with greater land urbanized 3-5 years ago. The results of this study suggest stream TP concentrations are relatively unresponsive to active versus established suburban cover, but the forms of TP can be quite different, and the period of home construction can increase phosphorus (P) delivery to and export through nearby streams. This information can aid land managers and urban planners update best management practices to

  10. Stream Tracker: Crowd sourcing and remote sensing to monitor stream flow intermittence

    Science.gov (United States)

    Puntenney, K.; Kampf, S. K.; Newman, G.; Lefsky, M. A.; Weber, R.; Gerlich, J.

    2017-12-01

    Streams that do not flow continuously in time and space support diverse aquatic life and can be critical contributors to downstream water supply. However, these intermittent streams are rarely monitored and poorly mapped. Stream Tracker is a community powered stream monitoring project that pairs citizen contributed observations of streamflow presence or absence with a network of streamflow sensors and remotely sensed data from satellites to track when and where water is flowing in intermittent stream channels. Citizens can visit sites on roads and trails to track flow and contribute their observations to the project site hosted by CitSci.org. Data can be entered using either a mobile application with offline capabilities or an online data entry portal. The sensor network provides a consistent record of streamflow and flow presence/absence across a range of elevations and drainage areas. Capacitance, resistance, and laser sensors have been deployed to determine the most reliable, low cost sensor that could be mass distributed to track streamflow intermittence over a larger number of sites. Streamflow presence or absence observations from the citizen and sensor networks are then compared to satellite imagery to improve flow detection algorithms using remotely sensed data from Landsat. In the first two months of this project, 1,287 observations have been made at 241 sites by 24 project members across northern and western Colorado.

  11. Pesticides in agricultural headwater streams in southwestern Germany and effects on macroinvertebrate populations.

    Science.gov (United States)

    Weber, Gero; Christmann, Nicole; Thiery, Ann-Cathrin; Martens, Dieter; Kubiniok, Jochen

    2018-04-01

    Pesticides are a major burden for stream ecosystems in the central European cultivated landscape. The objective of the present study was to investigate the applicability of ecological indicator methods in relation to toxicity of pesticides under the specific hydro-morphological conditions in small water bodies. Thus, an association of toxicity evaluating methods with different ecological indicators was to be attempted. Based on three random samples taken within the 2016 vegetation period, 23 headwater areas in the Saarland were investigated to test for pesticides and their metabolites. The macroinvertebrate population was also surveyed in 16 of these streams. Evidence was found of 41 substances in total. Most dominant substances include atrazine, isoproturone, quinmerac and tebuconazol as well as metabolites of dimethenamid, chloridazon and metazachlor. At 9 of the 23 sampling points, over 10 plant protection products and metabolites were found. Only 17% of the water bodies investigated contained fewer than 5 substances. Around half of the bodies of water investigated show noticeably high concentrations of metabolites of plant protection products. Maximum concentrations exceeding environmental quality standards or the Health-oriented Guideline Values were measured for 13 substances at individual sampling points. Analysis of the biological data for only 4 of the water bodies investigated resulted in the Ecological Status Class (ESC) "good". All others fell short of the quality target, although they were classified as "good" or "very good" according to the Saprobic index. SPEAR pesticides as a measurement of the sensitivity of the biocoenosis to pesticides shows their influence in a few water bodies. Likewise, high toxic unit values have also been calculated, indicating the presence of toxic substances at relevant concentrations. However, an actual correlation between SPEAR pesticides and toxic unit could not be derived. Clearly in these very headwater streams other

  12. Influence of bedrock geology on water chemistry of slope wetlands and headwater streams in the southern Rocky Mountains

    Science.gov (United States)

    Monique LaPerriere Nelson; Charles C. Rhoades; Kathleen A. Dwire

    2011-01-01

    We characterized the water chemistry of nine slope wetlands and adjacent headwater streams in Colorado subalpine forests and compared sites in basins formed on crystalline bedrock with those formed in basins with a mixture of crystalline and sedimentary bedrock. The pH, Ca2+, Mg2+, NH4 +, acid neutralizing capacity, and electrical conductivity of wetland porewater and...

  13. Abundance of western red-backed salamanders (Plethodon vehiculum) in the Washington Coast Range after headwater stream-buffer manipulation

    Science.gov (United States)

    Randall J. Wilk; Jeffrey D. Ricklefs; Martin G. Raphael

    2014-01-01

    We evaluated the effect of forest riparian alternative tree buffer designs on Western Red-backed Salamanders (Plethodon vehiculum) along headwater stream banks in managed forests of the Washington Coast Range. We used pit trap live removals in early autumn to estimate relative abundances of surface-active salamanders before and after 3 levels of riparian buffer...

  14. Export of detritus and invertebrate from headwater streams: linking mountaintop removal and valley fill coal mining to downstream receiving waters

    Science.gov (United States)

    Mountaintop removal and valley fill (MTR/VF) coal mining has resulted in large scale alteration of the topography, reduced forest productivity, and burial of headwater streams in the U.S. Central Appalachians. Although MTR/VF coal mining has occurred for several decades and the ...

  15. How and Why Does Stream Water Temperature Vary at Small Spatial Scales in a Headwater Stream?

    Science.gov (United States)

    Morgan, J. C.; Gannon, J. P.; Kelleher, C.

    2017-12-01

    The temperature of stream water is controlled by climatic variables, runoff/baseflow generation, and hyporheic exchange. Hydrologic conditions such as gaining/losing reaches and sources of inflow can vary dramatically along a stream on a small spatial scale. In this work, we attempt to discern the extent that the factors of air temperature, groundwater inflow, and precipitation influence stream temperature at small spatial scales along the length of a stream. To address this question, we measured stream temperature along the perennial stream network in a 43 ha catchment with a complex land use history in Cullowhee, NC. Two water temperature sensors were placed along the stream network on opposite sides of the stream at 100-meter intervals and at several locations of interest (i.e. stream junctions). The forty total sensors recorded the temperature every 10 minutes for one month in the spring and one month in the summer. A subset of sampling locations where stream temperature was consistent or varied from one side of the stream to the other were explored with a thermal imaging camera to obtain a more detailed representation of the spatial variation in temperature at those sites. These thermal surveys were compared with descriptions of the contributing area at the sample sites in an effort to discern specific causes of differing flow paths. Preliminary results suggest that on some branches of the stream stormflow has less influence than regular hyporheic exchange, while other tributaries can change dramatically with stormflow conditions. We anticipate this work will lead to a better understanding of temperature patterns in stream water networks. A better understanding of the importance of small-scale differences in flow paths to water temperature may be able to inform watershed management decisions in the future.

  16. Using high-frequency nitrogen and carbon measurements to decouple temporal dynamics of catchment and in-stream transport and reaction processes in a headwater stream

    Science.gov (United States)

    Blaen, P.; Riml, J.; Khamis, K.; Krause, S.

    2017-12-01

    Within river catchments across the world, headwater streams represent important sites of nutrient transformation and uptake due to their high rates of microbial community processing and relative abundance in the landscape. However, separating the combined influence of in-stream transport and reaction processes from the overall catchment response can be difficult due to spatio-temporal variability in nutrient and organic matter inputs, flow regimes, and reaction rates. Recent developments in optical sensor technologies enable high-frequency, in situ nutrient measurements, and thus provide opportunities for greater insights into in-stream processes. Here, we use in-stream observations of hourly nitrate (NO3-N), dissolved organic carbon (DOC) and dissolved oxygen (DO) measurements from paired in situ sensors that bound a 1 km headwater stream reach in a mixed-use catchment in central England. We employ a spectral approach to decompose (1) variances in solute loading from the surrounding landscape, and (2) variances in reach-scale in-stream nutrient transport and reaction processes. In addition, we estimate continuous rates of reach-scale NO3-N and DOC assimilation/dissimilation, ecosystem respiration and primary production. Comparison of these results over a range of hydrological conditions (baseflow, variable storm events) and timescales (event-based, diel, seasonal) facilitates new insights into the physical and biogeochemical processes that drive in-stream nutrient dynamics in headwater streams.

  17. Effects of acid mine drainage on a headwater stream ecosystem in Colorado

    International Nuclear Information System (INIS)

    Niyogi, D.K.; Lewis, W.M. Jr.; McKnight, D.M.

    1994-01-01

    The ecological effects of acid mine drainage were investigated during the summer of 1993 on St. Kevin Gulch, a headwater stream near Leadville, Colorado. The stream currently receives acidic water from an abandoned mine. The pH downstream of the mine is between 3.5 and 4.5, and several metals exceed concentrations toxic to aquatic organisms. Zinc is present at especially high concentrations (1 to 10 mg/L) Furthermore, the stream bottom is covered with a thick layer of iron hydroxide precipitates. Effects on stream biota have been dramatic. Aquatic flora in the affected reach is limited to a green filamentous alga, Ulothrix subtilissima. Macroinvertebrate densities are significantly lower in the affected reach (mean = 99 indiv/m 2 ; SD = 88 indiv/M 2 ) compared to an upstream (pristine) reference reach (mean = 1,735 indiv/m 2 ; SD = 652 indiv/M 2 ). Functional processes were also studied in the stream. Net primary production (NPP) was measured during midday with recirculating chambers. Production was significantly lower in the affected reach (mean NPP 13.3 MgO 2 hr -1 m -2 ; SD = 87 MgO 2 hr -1 m -2 ) than the upstream reference reach (NPP = 64.1 MgO 2 hr -1 m -2 ; SD = 27.7 MgO 2 hr -1 m -2 ). Decomposition, measured with litter bags, was also lower in the affected reach than the upstream site. In 1994, St. Kevin Gulch is scheduled to undergo remediation that will treat the acidic water from the mine. Further studies on this stream will provide information on the recovery processes in lotic ecosystems

  18. The Influence of Leaf Fall and Organic Carbon Availability on Nitrogen Cycling in a Headwater Stream

    Science.gov (United States)

    Thomas, S. A.; Kristin, A.; Doyle, B.; Goodale, C. L.; Gurwick, N. P.; Lepak, J.; Kulkari, M.; McIntyre, P.; McCalley, C.; Raciti, S.; Simkin, S.; Warren, D.; Weiss, M.

    2005-05-01

    The study of allochthonous carbon has a long and distinguished history in stream ecology. Despite this legacy, relatively little is known regarding the influence of leaf litter on nutrient dynamics. We conducted 15N-NO3 tracer additions to a headwater stream in upstate New York before and after autumn leaf fall to assess the influence of leaf litter on nitrogen spiraling. In addition, we amended the stream with labile dissolved organic carbon (as acetate) midway through each experiment to examine whether organic carbon availability differentially stimulated nitrogen cycling. Leaf standing stocks increased from 53 to 175 g dry mass m-2 and discharge more than tripled (6 to 20 L s-1) between the pre- and post-leaf fall period. In contrast, nitrate concentration fell from approximately 50 to less then 10 ug L-1. Despite higher discharge, uptake length was shorter following leaf fall under both ambient (250 and 72 m, respectively) and DOC amended (125 and 45 m) conditions. Uptake velocity increased dramatically following leaf fall, despite a slight decline in the areal uptake rate. Dissolved N2 gas samples were also collected to estimate denitrification rates under each experimental condition. The temporal extent of increased nitrogen retention will also be explored.

  19. Stream biofilm responses to flow intermittency: from cells to ecosystems

    Directory of Open Access Journals (Sweden)

    Sergi eSabater

    2016-03-01

    Full Text Available Temporary streams are characterized by the alternation of dry and wet hydrological phases, creating both a harsh environment for the biota as well as a high diversity of opportunities for adaptation. These systems are eminently microbial-based during several of these hydrological phases, and those growing on all solid substrata (biofilms accordingly change their physical structure and community composition. Biofilms experience large decreases on cell densities and biomass, both of bacteria and algae, during dryness. Algal and bacterial communities show remarkable decreases in their diversity, at least locally (at the habitat scale. Biofilms also respond with significant physiological plasticity to each of the hydrological changes. The decreasing humidity of the substrata through the drying process, and the changing quantity and quality of organic matter and nutrients available in the stream during that process, causes unequal responses on the biofilm bacteria and algae. Biofilm algae are affected faster than bacteria by the hydric stress, and as a result the ecosystem respiration resists longer than gross primary production to the increasing duration of flow intermittency. This response implies enhancing ecosystem heterotrophy, a pattern that can be exacerbated in temporary streams suffering of longer dry periods under global change.

  20. Relationships of sedimentation and benthic macroinvertebrate assemblages in headwater streams using systematic longitudinal sampling at the reach scale.

    Science.gov (United States)

    Longing, S D; Voshell, J R; Dolloff, C A; Roghair, C N

    2010-02-01

    Investigating relationships of benthic invertebrates and sedimentation is challenging because fine sediments act as both natural habitat and potential pollutant at excessive levels. Determining benthic invertebrate sensitivity to sedimentation in forested headwater streams comprised of extreme spatial heterogeneity is even more challenging, especially when associated with a background of historical and intense watershed disturbances that contributed unknown amounts of fine sediments to stream channels. This scenario exists in the Chattahoochee National Forest where such historical timber harvests and contemporary land-uses associated with recreation have potentially affected the biological integrity of headwater streams. In this study, we investigated relationships of sedimentation and the macroinvertebrate assemblages among 14 headwater streams in the forest by assigning 30, 100-m reaches to low, medium, or high sedimentation categories. Only one of 17 assemblage metrics (percent clingers) varied significantly across these categories. This finding has important implications for biological assessments by showing streams impaired physically by sedimentation may not be impaired biologically, at least using traditional approaches. A subsequent multivariate cluster analysis and indicator species analysis were used to further investigate biological patterns independent of sedimentation categories. Evaluating the distribution of sedimentation categories among biological reach clusters showed both within-stream variability in reach-scale sedimentation and sedimentation categories generally variable within clusters, reflecting the overall physical heterogeneity of these headwater environments. Furthermore, relationships of individual sedimentation variables and metrics across the biological cluster groups were weak, suggesting these measures of sedimentation are poor predictors of macroinvertebrate assemblage structure when using a systematic longitudinal sampling design

  1. Near-Term Effects of Repeated-Thinning with Riparian Buffers on Headwater Stream Vertebrates and Habitats in Oregon, USA

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    Deanna H. Olson

    2014-11-01

    Full Text Available We examined the effects of a second-thinning harvest with alternative riparian buffer management approaches on headwater stream habitats and associated vertebrates in western Oregon, USA. Our analyses showed that stream reaches were generally distinguished primarily by average width and depth, along with the percentage of the dry reach length, and secondarily, by the volume of down wood. In the first year post-harvest, we observed no effects of buffer treatment on stream habitat attributes after moderate levels of thinning. One of two “thin-through” riparian treatments showed stronger trends for enlarged stream channels, likely due to harvest disturbances. The effects of buffer treatments on salamanders varied among species and with habitat structure. Densities of Plethodon dunni and Rhyacotriton species increased post-harvest in the moderate-density thinning with no-entry buffers in wider streams with more pools and narrower streams with more down wood, respectively. However, Rhyacotriton densities decreased along streams with the narrowest buffer, 6 m, and P. dunni and Dicamptodon tenebrosus densities decreased in thin-through buffers. Our study supports the use of a 15-m or wider buffer to retain sensitive headwater stream amphibians.

  2. Identifying environmental and geochemical variables governing metal concentrations in a stream draining headwaters in NW Spain

    International Nuclear Information System (INIS)

    Soto-Varela, F.; Rodríguez-Blanco, M.L.; Taboada-Castro, M.M.; Taboada-Castro, M.T.

    2014-01-01

    Highlights: • All metals occur in association with suspended sediment. • DOC and SS appeared to influence the partitioning of metals. • The SS was a good predictor of particulate metal levels. • The most important variable to explain storm-event K D for Al and Fe is DOC. • Enrichment factor values suggest a natural origin for the particulate metals. - Abstract: Headwater stream, draining from a rural catchment in NW Spain, was sampled during baseflow and storm-event conditions to investigate the temporal variability in dissolved and particulate Al, Fe, Mn, Cu and Zn concentrations and the role of discharge (Q), pH, dissolved organic carbon (DOC) and suspended sediment (SS) in the transport of dissolved and particulate metals. Under baseflow and storm-event conditions, concentrations of the five metals were highly variable. The results of this study reveal that all metal concentrations are correlated with SS. DOC and SS appeared to influence both the metal concentrations and the partitioning of metals between dissolved and particulate. The SS was a good predictor of particulate metal levels. Distribution coefficients (K D ) were similar between metals (4.72–6.55) and did not change significantly as a function of discharge regime. Stepwise multiple linear regression analysis reveals that the most important variable to explain storm-event K D for Al and Fe is DOC. The positive relationships found between metals, in each fraction, indicate that these elements mainly come from the same source. Metal concentrations in the stream were relatively low

  3. Suggestions for diatom-based monitoring in intermittent streams

    Directory of Open Access Journals (Sweden)

    Falasco Elisa

    2016-01-01

    Full Text Available Over the last decades, river lentification processes and droughts have been dramatically spreading worldwide, due to global and local drastic changes due to human activities. Under this scenario, the evaluation of physical disturbance caused by intermittency and droughts has become more and more relevant. In this research, we compare samples collected in Mediterranean streams following both traditional and experimental approaches with the aim of understanding if diatom indices calculated from a new sampling strategy could provide additional information for the physical disturbance assessment. Moreover, we also evaluated the response of functional metrics. Our results demonstrated that even though an enhanced sampling method better reflects hydrological disturbance than the traditional one, diatom indices do not detect it. Conversely, functional traits proved to be important metrics for the hydrological disturbance assessment. In particular, benthic diatom chlorophyll a showed significantly lower values in sections more subject to droughts. With respect to ecological guilds, the motile taxa proved to be linked to depositional areas, which resulted important microhabitats (MHs to be explored in rivers affected by lentification. Including different MHs in the sampling process improves the information we can obtain from the analysis of the diatom community and presents important implications in documenting species distribution and autecology.

  4. Seasonal Stream Partitioning and Critical Zone Feedbacks within a Colorado River Headwater Basin

    Science.gov (United States)

    Carroll, R. W. H.; Bearup, L. A.; Williams, K. H.; Brown, W. S.; Dong, W.; Bill, M.

    2017-12-01

    Groundwater contribution to streams can modulate discharge response to climate extremes, thereby protecting ecosystem health and water supply for downstream users. However, much uncertainty exists on the role of groundwater contribution in snow-dominated, mountainous systems. To better understand seasonal stream source, we employ the empirical approach of end-member mixing analysis (EMMA) using a suite of natural chemical and isotopic observations within the East River; a headwater catchment of the Colorado River and recently designated as a Science Focus Area with Lawrence Berkeley National Laboratory. EMMA relies on principal component analysis to reduce the number of dimensions of variability (U-space) for use in hydrograph separation. The mixing model was constructed for the furthest downstream and most heavily characterized stream gauge in the study site (PH; 84.7 km2). Potential tracers were identified from PH discharge as near linear (Mg, Ca, Sr, U, SO4, DIC, δ2H and δ18O) with alternative groupings evaluated. The best model was able to describe 97% of the tracer variance in 2-dimensions with low error and lack of residual structure. U-space positioning resulted in seasonal stream water source contributions of rain (8-16%), snow (48-74%) and groundwater (18-42%). EMMA developed for PH did not scale across 10 nested sub-basins (ranging from 0.38 km2 to 69.9 km2). Differences in mixing ratios are attributable to feedbacks in the critical zone with a focus on (1) source rock contributions of SO4 and U; (2) biogeochemical processes of enhanced SO4 reduction in the floodplain sediments, (3) flow path length as expressed by carbonate weathering, and (4) enhanced groundwater contributions as related to snow distribution and ecosystem structure. EMMA is an initial step to elucidate source contributions to streamflow and address scalability and applicability of mixing processes in a complex, highly heterogeneous, snow-dominated catchment. Work will aid hydrologic

  5. Applying High-Resolution Imagery to Evaluate Restoration-Induced Changes in Stream Condition, Missouri River Headwaters Basin, Montana

    Directory of Open Access Journals (Sweden)

    Melanie K. Vanderhoof

    2018-06-01

    Full Text Available Degradation of streams and associated riparian habitat across the Missouri River Headwaters Basin has motivated several stream restoration projects across the watershed. Many of these projects install a series of beaver dam analogues (BDAs to aggrade incised streams, elevate local water tables, and create natural surface water storage by reconnecting streams with their floodplains. Satellite imagery can provide a spatially continuous mechanism to monitor the effects of these in-stream structures on stream surface area. However, remote sensing-based approaches to map narrow (e.g., <5 m wide linear features such as streams have been under-developed relative to efforts to map other types of aquatic systems, such as wetlands or lakes. We mapped pre- and post-restoration (one to three years post-restoration stream surface area and riparian greenness at four stream restoration sites using Worldview-2 and 3 images as well as a QuickBird-2 image. We found that panchromatic brightness and eCognition-based outputs (0.5 m resolution provided high-accuracy maps of stream surface area (overall accuracy ranged from 91% to 99% for streams as narrow as 1.5 m wide. Using image pairs, we were able to document increases in stream surface area immediately upstream of BDAs as well as increases in stream surface area along the restoration reach at Robb Creek, Alkali Creek and Long Creek (South. Although Long Creek (North did not show a net increase in stream surface area along the restoration reach, we did observe an increase in riparian greenness, suggesting increased water retention adjacent to the stream. As high-resolution imagery becomes more widely collected and available, improvements in our ability to provide spatially continuous monitoring of stream systems can effectively complement more traditional field-based and gage-based datasets to inform watershed management.

  6. Effects of chronic pollution and water flow intermittency on stream biofilms biodegradation capacity.

    Science.gov (United States)

    Rožman, Marko; Acuña, Vicenç; Petrović, Mira

    2018-02-01

    A mesocosm case study was conducted to gain understanding and practical knowledge on biofilm emerging contaminants biodegradation capacity under stressor and multiple stressor conditions. Two real life scenarios: I) biodegradation in a pristine intermittent stream experiencing acute pollution and II) biodegradation in a chronically polluted intermittent stream, were examined via a multifactorial experiment using an artificial stream facility. Stream biofilms were exposed to different water flow conditions i.e. permanent and intermittent water flow. Venlafaxine, a readily biodegradable pharmaceutical was used as a measure of biodegradation capacity while pollution was simulated by a mixture of four emerging contaminants (erythromycin, sulfisoxazole, diclofenac and imidacloprid in addition to venlafaxine) in environmentally relevant concentrations. Biodegradation kinetics monitored via LC-MS/MS was established, statistically evaluated, and used to link biodegradation with stress events. The results suggest that the effects of intermittent flow do not hinder and may even stimulate pristine biofilm biodegradation capacity. Chronic pollution completely reduced biodegradation in permanent water flow experimental treatments while no change in intermittent streams was observed. A combined effect of water flow conditions and emerging contaminants exposure on biodegradation was found. The decrease in biodegradation due to exposure to emerging contaminants is significantly greater in streams with permanent water flow suggesting that the short and medium term biodegradation capacity in intermittent systems may be preserved or even greater than in perennial streams. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Headwater streams in the EU Water Framework Directive: Evidence-based decision support to select streams for river basin management plans

    DEFF Research Database (Denmark)

    Baattrup-Pedersen, Annette; Larsen, Søren Erik; Andersen, Dagmar K.

    2018-01-01

    , however, it is intensely debated whether the small size and low slopes, typical of Danish streams, in combination with degraded habitat conditions obstruct their ability to fulfill the ecological quality objectives required by the EU Water Framework Directive (WFD). The purpose of this studywas to provide...... an analytically based framework for guiding the selection of headwater streams for RBMP. Specifically, the following hypotheses were addressed: i) stream slope, width, planform, and general physical habitat quality can act as criteria for selecting streams for the next generation of RBMPs, and ii) probability......-based thresholds for reaching good ecological status can be established for some or all of these criteria, thus creating a sound, scientifically based, and clear selection process. The hypotheses were tested using monitoring data on Danish streams from the period 2004–2015. Significant linear relationships were...

  8. Subsurface Controls on Stream Intermittency in a Semi-Arid Landscape

    Science.gov (United States)

    Dohman, J.; Godsey, S.; Thackray, G. D.; Hale, R. L.; Wright, K.; Martinez, D.

    2017-12-01

    Intermittent streams currently constitute 30% to greater than 50% of the global river network. In addition, the number of intermittent streams is expected to increase due to changes in land use and climate. These streams provide important ecosystem services, such as water for irrigation, increased biodiversity, and high rates of nutrient cycling. Many hydrological studies have focused on mapping current intermittent flow regimes or evaluating long-term flow records, but very few have investigated the underlying causes of stream intermittency. The disconnection and reconnection of surface flow reflects the capacity of the subsurface to accommodate flow, so characterizing subsurface flow is key to understanding stream drying. We assess how subsurface flow paths control local surface flows during low-flow periods, including intermittency. Water table dynamics were monitored in an intermittent reach of Gibson Jack Creek in southeastern Idaho. Four transects were delineated with a groundwater well located in the hillslope, riparian zone, and in the stream, for a total of 12 groundwater wells. The presence or absence of surface flow was determined by frequent visual observations as well as in situ loggers every 30m along the 200m study reach. The rate of surface water drying was measured in conjunction with temperature, precipitation, subsurface hydraulic conductivity, hillslope-riparian-stream connectivity and subsurface travel time. Initial results during an unusually wet year suggest different responses in reaches that were previously observed to occasionally cease flowing. Flows in the intermittent reaches had less coherent and lower amplitude diel variations during base flow periods than reaches that had never been observed to dry out. Our findings will help contribute to our understanding of mechanisms driving expansion and contraction cycles in intermittent streams, increase our ability to predict how land use and climate change will affect flow regimes, and

  9. The effects of human land use on flow regime and water chemistry of headwater streams in the highlands of Chiapas

    Directory of Open Access Journals (Sweden)

    Castillo M.M.

    2013-03-01

    Full Text Available We studied the effects of land use changes on flow regime and water chemistry of headwater streams in the highlands of Chiapas, a region in southern Mexico that has experienced high rates of deforestation in the last decades. Samples for water chemistry were collected and discharge was measured between September 2007 and August 2008 at eight streams that differed in the land uses of their riparian and catchment areas, including streams draining protected forested areas. Streams with high forest cover (>70% in their catchments maintained flow through the year. Streams draining more disturbed catchments exhibited reduced or no flow for 4 − 6 months during the dry season. Nitrate concentrations were lower at streams draining forested catchments while highest concentrations were measured where conventional agriculture covered a high proportion of the catchment and riparian zone. Highest phosphorus concentrations occurred at the catchment where poultry manure was applied as fertilizer. Differences between forest streams and those draining disturbed areas were correlated with the proportion of forest and agriculture in the riparian zone. Variation in stream variables among sampling dates was lower at the forest sites than at the more disturbed study streams. Conversion of forest into agriculture and urban areas is affecting flow regime and increasing nutrient concentrations, although the magnitude of the impacts are influenced by the type of agricultural practices and the alteration of the riparian zone.

  10. Hydro-climatic control of stream dissolved organic carbon in headwater catchment

    Science.gov (United States)

    Humbert, Guillaume; Jaffrezic, Anne; Fovet, Ophélie; Gruau, Gérard; Durand, Patrick

    2014-05-01

    Dissolved organic matter (DOM) is a key form of the organic matter linking together the water and the carbon cycles and interconnecting the biosphere (terrestrial and marine) and the soil. At the landscape scale, land use and hydrology are the main factors controlling the amount of DOM transferred from soils to the stream. In an intensively cultivated catchment, a recent work using isotopic composition of DOM as a marker has identified two different sources of DOM. The uppermost soil horizons of the riparian wetland appear as a quasi-infinite source while the topsoil of the hillslope forms a limited one mobilized by water-table rise and exported to the stream across the upland-riparian wetland-stream continuum. In addition to the exportation of DOM via water fluxes, climatic factors like temperature and precipitation regulate the DOM production by influencing microbial activity and soil organic matter degradation. The small headwater catchment (5 km²) of Kervidy-Naizin located in Brittany is part of the Environment Research Observatory (ORE) AgrHys. Weather and the hydro-chemistry of the stream, and the groundwater levels are daily recorded since 1993, 2000 and 2001 respectively. Over 13 contrasted hydrological years, the annual flow weighted mean concentration of dissolved organic carbon (DOC) is 5.6 mg.L-1 (sd = 0.7) for annual precipitation varying from 488mm to 1327mm and annual mean temperatures of 11°C (sd = 0.6). Based on this considerable dataset and this annual variability, we tried to understand how the hydro-climatic conditions determinate the stream DOC concentrations along the year. From the fluctuations of water table depth, each hydrologic year has been divided into three main period: i) progressive rewetting of the riparian wetland soils, ii) rising and holding high of the water table in the hillslope, iii) drawdown of the water-table, with less and less topsoil connected to the stream. Within each period base flow and storm flow data were first

  11. Carbon cycling and exports over diel and flood-recovery timescales in a subtropical rainforest headwater stream

    International Nuclear Information System (INIS)

    Looman, Arún; Santos, Isaac R.; Tait, Douglas R.; Webb, Jackie R.; Sullivan, Caroline A.; Maher, Damien T.

    2016-01-01

    Catchment headwaters comprise the majority of all stream length globally, however, carbon (C) dynamics in these systems remains poorly understood. We combined continuous measurements of pCO_2 and radon ("2"2"2Rn, a natural groundwater tracer) with discrete sampling for particulate organic, dissolved organic and inorganic carbon (POC, DOC, and DIC) to assess the short-term carbon dynamics of a pristine subtropical headwater stream in Australia, over contrasting hydrologic regimes of drought, flash-flooding and recovery. Observations over 23 days revealed a shift from carbon losses dominated by CO_2 outgassing under conditions of low flow (66.4 ± 0.4% of carbon export) to downstream exports of carbon during the flood (87.8 ± 9.7% of carbon export). DOC was the dominant form of downstream exports throughout the study (DOC:DIC:POC = 0.82:0.05:0.13). The broadest diel variability among variables occurred during the drought phase, with diel variability up to 662 μatm d"−"1 (or 27 μM [CO_2*] d"−"1), 17 μM d"−"1 and 268 Bq m"−"3 d"−"1 for pCO_2, dissolved oxygen and "2"2"2Rn, respectively. Diel dynamics indicated multiple interrelated drivers of stream water chemistry including groundwater seepage and in-stream metabolism. The catchment exported terrestrial carbon throughout the field campaign, with a mean net stream flux of 4.7 ± 7.8 mmol C m"−"2 (catchment area) d"−"1 which is equivalent to 1.4 ± 2.3% of the estimated local terrestrial net primary production. Our observations highlight the importance of accounting for hydrological extremes when assessing the carbon budgets and ecosystem metabolism of headwater streams, and provide a first estimate of aquatic carbon exports from a pristine Australian subtropical rainforest. - Highlights: • First carbon export estimates of a pristine Australian subtropical headwater catchment. • Metabolism and hydrology were drivers of aquatic carbon flux. • Catchment exports ranged between 1.1 and 18.6 mmol C m

  12. Carbon cycling and exports over diel and flood-recovery timescales in a subtropical rainforest headwater stream

    Energy Technology Data Exchange (ETDEWEB)

    Looman, Arún, E-mail: arun.looman@scu.edu.au [National Marine Science Centre, Southern Cross University, Coffs Harbour, New South Wales (Australia); School of Environment, Science, and Engineering, Southern Cross University, Lismore, New South Wales (Australia); Santos, Isaac R.; Tait, Douglas R.; Webb, Jackie R. [National Marine Science Centre, Southern Cross University, Coffs Harbour, New South Wales (Australia); School of Environment, Science, and Engineering, Southern Cross University, Lismore, New South Wales (Australia); Sullivan, Caroline A.; Maher, Damien T. [School of Environment, Science, and Engineering, Southern Cross University, Lismore, New South Wales (Australia)

    2016-04-15

    Catchment headwaters comprise the majority of all stream length globally, however, carbon (C) dynamics in these systems remains poorly understood. We combined continuous measurements of pCO{sub 2} and radon ({sup 222}Rn, a natural groundwater tracer) with discrete sampling for particulate organic, dissolved organic and inorganic carbon (POC, DOC, and DIC) to assess the short-term carbon dynamics of a pristine subtropical headwater stream in Australia, over contrasting hydrologic regimes of drought, flash-flooding and recovery. Observations over 23 days revealed a shift from carbon losses dominated by CO{sub 2} outgassing under conditions of low flow (66.4 ± 0.4% of carbon export) to downstream exports of carbon during the flood (87.8 ± 9.7% of carbon export). DOC was the dominant form of downstream exports throughout the study (DOC:DIC:POC = 0.82:0.05:0.13). The broadest diel variability among variables occurred during the drought phase, with diel variability up to 662 μatm d{sup −1} (or 27 μM [CO{sub 2}*] d{sup −1}), 17 μM d{sup −1} and 268 Bq m{sup −3} d{sup −1} for pCO{sub 2}, dissolved oxygen and {sup 222}Rn, respectively. Diel dynamics indicated multiple interrelated drivers of stream water chemistry including groundwater seepage and in-stream metabolism. The catchment exported terrestrial carbon throughout the field campaign, with a mean net stream flux of 4.7 ± 7.8 mmol C m{sup −2} (catchment area) d{sup −1} which is equivalent to 1.4 ± 2.3% of the estimated local terrestrial net primary production. Our observations highlight the importance of accounting for hydrological extremes when assessing the carbon budgets and ecosystem metabolism of headwater streams, and provide a first estimate of aquatic carbon exports from a pristine Australian subtropical rainforest. - Highlights: • First carbon export estimates of a pristine Australian subtropical headwater catchment. • Metabolism and hydrology were drivers of aquatic carbon flux.

  13. Macroinvertebrate and organic matter export from headwater tributaries of a Central Appalachian stream

    Data.gov (United States)

    U.S. Environmental Protection Agency — The dataset contains physicochemical and biological data from 12 headwater tributaries of Clemons Fork in Robinson Forest, KY. This dataset is associated with the...

  14. The influence of riparian-hyporheic zone on the hydrological responses in an intermittent stream

    Directory of Open Access Journals (Sweden)

    A. Butturini

    2002-01-01

    Full Text Available Stream and riparian groundwater hydrology has been studied in a small intermittent stream draining a forested catchment for a system representative of a Mediterranean climate. The relationship between precipitation and stream runoff and the interactions between stream water and the surrounding riparian groundwater have been analysed under a wide spectrum of meteorological conditions. The hypothesis that the hydrological condition of the near-stream groundwater compartment can regulate the runoff generation during precipitation events was tested. Stream runoff is characterised by a summer dry period, and precipitation input explained only 25% of runoff variability over the study period (r2 =0.25, d.f.=51, p2=0.80, d.f.=34, p Keywords: riparian zone, groundwater hydrology, runoff, intermittent stream, Mediterranean climate

  15. Initial response of small ground-dwelling mammals to forest alternative buffers along headwater streams in the Washington Coast Range, USA

    Science.gov (United States)

    Randall J. Wilk; Martin G. Raphael; Christopher S. Nations; Jeffrey D. Ricklefs

    2010-01-01

    We assessed the short-term effects of alternative designs of forested buffer treatments along headwater streams on small ground-dwelling mammals in managed forests in western Washington, USA. Over three summers (one pretreatment and two posttreatment), we trapped 19 mammalian species along 23 streams in the northern Coast Range. We compared faunal communities in...

  16. Sensitivity of intermittent streams to climate variations in the United States

    Science.gov (United States)

    Eng, K.

    2015-12-01

    There is growing interest in the effects of climate change on streamflows because of the potential negative effects on aquatic biota and water supplies. Previous studies of climate controls on flows have primarily focused on perennial streams, and few studies have examined the effect of climate variability on intermittent streams. Our objectives in this study were to (1) identify regions showing similar patterns of intermittency, and (2) evaluate the sensitivity of intermittent streams to historical variability in climate in the United States. This study was carried out at 265 intermittent streams by evaluating: (1) correlations among time series of flow metrics (number of zero-flow events, the average of the central 50% and largest 10% of flows) with precipitation (magnitudes, durations and intensity) and temperature, and (2) decadal changes in the seasonality and long-term trends of these flow metrics. Results identified five distinct seasonal patterns of flow intermittency: fall, fall-to-winter, non-seasonal, summer, and summer-to-winter intermittent streams. In addition, strong associations between the low-flow metrics and historical climate variability were found. However, the lack of trends in historical variations in precipitation results in no significant seasonal shifts or decade-to-decade trends in the low-flow metrics over the period of record (1950 to 2013).

  17. Links between riparian landcover, instream environment and fish assemblages in headwater streams of south-eastern Brazil

    Science.gov (United States)

    Cruz, Bruna B.; Miranda, Leandro E.; Cetra, Mauricio

    2013-01-01

    We hypothesised and tested a hierarchical organisation model where riparian landcover would influence bank composition and light availability, which in turn would influence instream environments and control fish assemblages. The study was conducted during the dry season in 11 headwater tributaries of the Sorocaba River in the upper Paraná River Basin, south-eastern Brazil. We focused on seven environmental factors each represented by one or multiple environmental variables and seven fish functional traits each represented by two or more classes. Multivariate direct gradient analyses suggested that riparian zone landcover can be considered a higher level causal factor in a network of relations that control instream characteristics and fish assemblages. Our results provide a framework for a hierarchical conceptual model that identifies singular and collective influences of variables from different scales on each other and ultimately on different aspects related to stream fish functional composition. This conceptual model is focused on the relationships between riparian landcover and instream variables as causal factors on the organisation of stream fish assemblages. Our results can also be viewed as a model for headwater stream management in that landcover can be manipulated to influence factors such as bank composition, substrates and water quality, whereas fish assemblage composition can be used as indicators to monitor the success of such efforts.

  18. A stream sediment geochemical survey of the Ganga River headwaters in the Garhwal Himalaya

    Science.gov (United States)

    Mukherjee, P.K.; Purohit, K.K.; Saini, N.K.; Khanna, P.P.; Rathi, M.S.; Grosz, A.E.

    2007-01-01

    This study models geochemical and adjunct geologic data to define provinces that are favorable for radioactive-mineral exploration. A multi-element bed-sediment geochemical survey of streams was carried out in the headwaters region of the Ganga River in northern India. Overall median values for uranium and thorium (3.6 and 13.8 ppm; maxima of 4.8 and 19.0 ppm and minima of 3.1 and 12.3 ppm respectively) exceed average upper crustal abundances (2.8 and 10.7 ppm) for these radioactive elements. Anomalously high values reach up to 8.3 and 30.1 ppm in thrust zone rocks, and 11.4 and 22.5 ppm in porphyroids. At their maxima, these abundances are nearly four- and three-fold (respectively) enriched in comparison to average crustal abundances for these rock types. Deformed, metamorphosed and sheared rocks are characteristic of the main central thrust zone (MCTZ). These intensively mylonitized rocks override and juxtapose porphyritic (PH) and proterozoic metasedimentary rock sequences (PMS) to the south. Granitoid rocks, the major protoliths for mylonites, as well as metamorphosed rocks in the MCT zone are naturally enriched in radioelements; high values associated with sheared and mylonitized zones are coincident with reports of radioelement mineralization and with anomalous radon concentrations in soils. The radioelement abundance as well as REE abundance shows a northward enrichment trend consistent with increasing grade of metamorphism indicating deformation-induced remobilization of these elements. U and Th illustrate good correlation with REEs but not with Zr. This implies that zircon is not a principal carrier of U and Th within the granitoid-dominant thrust zone and that other radioelement-rich secondary minerals are present in considerable amounts. Thus, the relatively flat, less fractionated, HREE trend is also not entirely controlled by zircon. The spatial correlation of geologic boundary zones (faults, sheared zones) with geochemical and with geophysical (Rn

  19. Environmental DNA method for estimating salamander distribution in headwater streams, and a comparison of water sampling methods.

    Science.gov (United States)

    Katano, Izumi; Harada, Ken; Doi, Hideyuki; Souma, Rio; Minamoto, Toshifumi

    2017-01-01

    Environmental DNA (eDNA) has recently been used for detecting the distribution of macroorganisms in various aquatic habitats. In this study, we applied an eDNA method to estimate the distribution of the Japanese clawed salamander, Onychodactylus japonicus, in headwater streams. Additionally, we compared the detection of eDNA and hand-capturing methods used for determining the distribution of O. japonicus. For eDNA detection, we designed a qPCR primer/probe set for O. japonicus using the 12S rRNA region. We detected the eDNA of O. japonicus at all sites (with the exception of one), where we also observed them by hand-capturing. Additionally, we detected eDNA at two sites where we were unable to observe individuals using the hand-capturing method. Moreover, we found that eDNA concentrations and detection rates of the two water sampling areas (stream surface and under stones) were not significantly different, although the eDNA concentration in the water under stones was more varied than that on the surface. We, therefore, conclude that eDNA methods could be used to determine the distribution of macroorganisms inhabiting headwater systems by using samples collected from the surface of the water.

  20. Factors influencing retention of visible implant tags by westslope cutthroat trout inhabiting headwater streams of Montana

    Science.gov (United States)

    Bradley B. Shepard; Jim Robison-Cox; Susan C. Ireland; Robert G. White

    1996-01-01

    Retention of visible implant (VI) tags by westslope cutthroat trout Oncorhynchus clarki lewisi inhabiting 20 reaches of 13 isolated headwater tributary drainages in Montana was evaluated during 1993 and 1994. In 1993, 2,071 VI tags were implanted in westslope cutthroat trout (100-324 mm fork length) and adipose tins were removed as a secondary mark to evaluate tag...

  1. Curve number derivation for watersheds draining two headwater streams in lower coastal plain South Carolina, USA

    Science.gov (United States)

    Thomas H. Epps; Daniel R. Hitchcock; Anand D. Jayakaran; Drake R. Loflin; Thomas M. Williams; Devendra M. Amatya

    2013-01-01

    The objective of this study was to assess curve number (CN) values derived for two forested headwater catchments in the Lower Coastal Plain (LCP) of South Carolina using a three-year period of storm event rainfall and runoff data in comparison with results obtained from CN method calculations. Derived CNs from rainfall/runoff pairs ranged from 46 to 90 for the Upper...

  2. An assessment of cellulose filters as a standardized material for measuring litter breakdown in headwater streams

    Science.gov (United States)

    The decay rate of cellulose filters and associated chemical and biological characteristics were compared to those of white oak (Quercus alba) leaves to determine if cellulose filters could be a suitable standardized material for measuring deciduous leaf breakdown in headwater str...

  3. Implementation of a subcanopy solar radiation model on a forested headwater basin in the Southern Appalachians to estimate riparian canopy density and stream insolation for stream temperature models

    Science.gov (United States)

    Belica, L.; Petras, V.; Iiames, J. S., Jr.; Caldwell, P.; Mitasova, H.; Nelson, S. A. C.

    2016-12-01

    Water temperature is a key aspect of water quality and understanding how the thermal regimes of forested headwater streams may change in response to climatic and land cover changes is increasingly important to scientists and resource managers. In recent years, the forested mountain watersheds of the Southeastern U.S. have experienced changing climatic patterns as well as the loss of a keystone riparian tree species and anticipated hydrologic responses include lower summer stream flows and decreased stream shading. Solar radiation is the main source of thermal energy to streams and a key parameter in heat-budget models of stream temperature; a decrease in flow volume combined with a reduction in stream shading during summer have the potential to increase stream temperatures. The high spatial variability of forest canopies and the high spatio-temporal variability in sky conditions make estimating the solar radiation reaching small forested headwater streams difficult. The Subcanopy Solar Radiation Model (SSR) (Bode et al. 2014) is a GIS model that generates high resolution, spatially explicit estimates of solar radiation by incorporating topographic and vegetative shading with a light penetration index derived from leaf-on airborne LIDAR data. To evaluate the potential of the SSR model to provide estimates of stream insolation to parameterize heat-budget models, it was applied to the Coweeta Basin in the Southern Appalachians using airborne LIDAR (NCALM 2009, 1m resolution). The LIDAR derived canopy characteristics were compared to current hyperspectral images of the canopy for changes and the SSR estimates of solar radiation were compared with pyranometer measurements of solar radiation at several subcanopy sites during the summer of 2016. Preliminary results indicate the SSR model was effective in identifying variations in canopy density and light penetration, especially in areas associated with road and stream corridors and tree mortality. Current LIDAR data and

  4. Compliance of secondary production and eco-exergy as indicators of benthic macroinvertebrates assemblages' response to canopy cover conditions in Neotropical headwater streams.

    Science.gov (United States)

    Linares, Marden Seabra; Callisto, Marcos; Marques, João Carlos

    2018-02-01

    Riparian vegetation cover influences benthic assemblages structure and functioning in headwater streams, as it regulates light availability and autochthonous primary production in these ecosystems.Secondary production, diversity, and exergy-based indicators were applied in capturing how riparian cover influences the structure and functioning of benthic macroinvertebrate assemblages in tropical headwater streams. Four hypotheses were tested: (1) open canopy will determine the occurrence of higher diversity in benthic macroinvertebrate assemblages; (2) streams with open canopy will exhibit more complex benthic macroinvertebrate communities (in terms of information embedded in the organisms' biomass); (3) in streams with open canopy benthic macroinvertebrate assemblages will be more efficient in using the available resources to build structure, which will be reflected by higher eco-exergy values; (4) benthic assemblages in streams with open canopy will exhibit more secondary productivity. We selected eight non-impacted headwater streams, four shaded and four with open canopy, all located in the Neotropical savannah (Cerrado) of southeastern Brazil. Open canopy streams consistently exhibited significantly higher eco-exergy and instant secondary production values, exemplifying that these streams may support more complex and productive benthic macroinvertebrate assemblages. Nevertheless, diversity indices and specific eco-exergy were not significantly different in shaded and open canopy streams. Since all the studied streams were selected for being considered as non-impacted, this suggests that the potential represented by more available food resources was not used to build a more complex dissipative structure. These results illustrate the role and importance of the canopy cover characteristics on the structure and functioning of benthic macroinvertebrate assemblages in tropical headwater streams, while autochthonous production appears to play a crucial role as food

  5. Water chemistry in 179 randomly selected Swedish headwater streams related to forest production, clear-felling and climate.

    Science.gov (United States)

    Löfgren, Stefan; Fröberg, Mats; Yu, Jun; Nisell, Jakob; Ranneby, Bo

    2014-12-01

    From a policy perspective, it is important to understand forestry effects on surface waters from a landscape perspective. The EU Water Framework Directive demands remedial actions if not achieving good ecological status. In Sweden, 44 % of the surface water bodies have moderate ecological status or worse. Many of these drain catchments with a mosaic of managed forests. It is important for the forestry sector and water authorities to be able to identify where, in the forested landscape, special precautions are necessary. The aim of this study was to quantify the relations between forestry parameters and headwater stream concentrations of nutrients, organic matter and acid-base chemistry. The results are put into the context of regional climate, sulphur and nitrogen deposition, as well as marine influences. Water chemistry was measured in 179 randomly selected headwater streams from two regions in southwest and central Sweden, corresponding to 10 % of the Swedish land area. Forest status was determined from satellite images and Swedish National Forest Inventory data using the probabilistic classifier method, which was used to model stream water chemistry with Bayesian model averaging. The results indicate that concentrations of e.g. nitrogen, phosphorus and organic matter are related to factors associated with forest production but that it is not forestry per se that causes the excess losses. Instead, factors simultaneously affecting forest production and stream water chemistry, such as climate, extensive soil pools and nitrogen deposition, are the most likely candidates The relationships with clear-felled and wetland areas are likely to be direct effects.

  6. Exploration of diffuse and discrete sources of acid mine drainage to a headwater mountain stream in Colorado, USA

    Science.gov (United States)

    Johnston, Allison; Runkel, Robert L.; Navarre-Sitchler, Alexis; Singha, Kamini

    2017-01-01

    We investigated the impact of acid mine drainage (AMD) contamination from the Minnesota Mine, an inactive gold and silver mine, on Lion Creek, a headwater mountain stream near Empire, Colorado. The objective was to map the sources of AMD contamination, including discrete sources visible at the surface and diffuse inputs that were not readily apparent. This was achieved using geochemical sampling, in-stream and in-seep fluid electrical conductivity (EC) logging, and electrical resistivity imaging (ERI) of the subsurface. The low pH of the AMD-impacted water correlated to high fluid EC values that served as a target for the ERI. From ERI, we identified two likely sources of diffuse contamination entering the stream: (1) the subsurface extent of two seepage faces visible on the surface, and (2) rainfall runoff washing salts deposited on the streambank and in a tailings pile on the east bank of Lion Creek. Additionally, rainfall leaching through the tailings pile is a potential diffuse source of contamination if the subsurface beneath the tailings pile is hydraulically connected with the stream. In-stream fluid EC was lowest when stream discharge was highest in early summer and then increased throughout the summer as stream discharge decreased, indicating that the concentration of dissolved solids in the stream is largely controlled by mixing of groundwater and snowmelt. Total dissolved solids (TDS) load is greatest in early summer and displays a large diel signal. Identification of diffuse sources and variability in TDS load through time should allow for more targeted remediation options.

  7. Factors affecting distribution of wood, detritus, and sediment in headwater streams draining managed young-growth red alder - Conifer forests in southeast Alaska

    Science.gov (United States)

    Gomi, T.; Johnson, A.C.; Deal, R.L.; Hennon, P.E.; Orlikowska, E.H.; Wipfli, M.S.

    2006-01-01

    Factors (riparian stand condition, management regimes, and channel properties) affecting distributions of wood, detritus (leaves and branches), and sediment were examined in headwater streams draining young-growth red alder (Alnus rubra Bong.) - conifer riparian forests (40 years old) remained in channels and provided sites for sediment and organic matter storage. Despite various alder-conifer mixtures and past harvesting effects, the abundance of large wood, fine wood, and detritus accumulations significantly decreased with increasing channel bank-full width (0.5-3.5 m) along relatively short channel distances (up to 700 m). Changes in wood, detritus, and sediment accumulations together with changes in riparian stand characteristics create spatial and temporal variability of in-channel conditions in headwater systems. A component of alder within young-growth riparian forests may benefit both wood production and biological recovery in disturbed headwater stream channels. ?? 2006 NRC.

  8. Seasonal size distribution of three-spined stickleback in an intermittent/perennial stream system

    Science.gov (United States)

    To better understand patterns of habitat use by fish in an intermittent stream, we have been investigating the early life history of three-spined stickleback (Gasterosteus aculeatus). We collected three-spined stickleback and other fishes using dipnets, seines and minnow traps ...

  9. High rates of organic carbon processing in the hyporheic zone of intermittent streams.

    Science.gov (United States)

    Burrows, Ryan M; Rutlidge, Helen; Bond, Nick R; Eberhard, Stefan M; Auhl, Alexandra; Andersen, Martin S; Valdez, Dominic G; Kennard, Mark J

    2017-10-16

    Organic carbon cycling is a fundamental process that underpins energy transfer through the biosphere. However, little is known about the rates of particulate organic carbon processing in the hyporheic zone of intermittent streams, which is often the only wetted environment remaining when surface flows cease. We used leaf litter and cotton decomposition assays, as well as rates of microbial respiration, to quantify rates of organic carbon processing in surface and hyporheic environments of intermittent and perennial streams under a range of substrate saturation conditions. Leaf litter processing was 48% greater, and cotton processing 124% greater, in the hyporheic zone compared to surface environments when calculated over multiple substrate saturation conditions. Processing was also greater in more saturated surface environments (i.e. pools). Further, rates of microbial respiration on incubated substrates in the hyporheic zone were similar to, or greater than, rates in surface environments. Our results highlight that intermittent streams are important locations for particulate organic carbon processing and that the hyporheic zone sustains this fundamental process even without surface flow. Not accounting for carbon processing in the hyporheic zone of intermittent streams may lead to an underestimation of its local ecological significance and collective contribution to landscape carbon processes.

  10. Thermal Fluxes and Temperatures in Small Urban Headwater Streams of the BES LTER: Landscape Forest and Impervious Patches and the Importance of Spatial and Temporal Scales

    Science.gov (United States)

    Kim, H.; Belt, K. T.; Welty, C.; Heisler, G.; Pouyat, R. V.; McGuire, M. P.; Stack, W. P.

    2006-05-01

    Water and material fluxes from urban landscape patches to small streams are modulated by extensive "engineered" drainage networks. Small urban headwater catchments are different in character and function from their larger receiving streams because of their extensive, direct connections to impervious surface cover (ISC) and their sometimes buried nature. They need to be studied as unique functional hydrologic units if impacts on biota are to be fully understood. As part of the Baltimore Ecosystem Study LTER project, continuous water temperature data are being collected at 2-minute intervals at over twenty small catchments representing various mixtures of forest and ISC. Suburban stream sites with greater ISC generally have higher summer water temperatures. Suburban catchments with most of their channel drainage contained within storm drain pipes show subdued diurnal variation and cool temperatures, but with very large spikes in summer runoff events. Conversely, high ISC urban piped streams have elevated "baseline" temperatures that stand well above all the other monitoring sites. There is a pronounced upstream-downstream effect; nested small headwater catchments experience more frequent, larger temperature spikes related to runoff events than downstream sites. Also, runoff-initiated temperature elevations at small stream sites unexpectedly last much longer than the storm runoff hydrographs. These observations suggest that for small headwater catchments, urban landscapes not only induce an ambient, "heat island" effect on stream temperatures, but also introduce thermal disturbance regimes and fluxes that are not trivial to aquatic biota.

  11. Tracking Changes in Dissolved Organic Matter Patterns in Perennial Headwater Streams Throughout a Hydrologic Year Using In-situ Sensors and Optical Properties

    Science.gov (United States)

    Armstrong, A.; Epting, S.; Hosen, J. D.; Palmer, M.

    2015-12-01

    Dissolved organic matter (DOM) plays a central role in freshwater streams but key questions remain unanswered about temporal patterns in its quantity and composition. DOM in perennial streams in the temperate zone is a complex mixture reflecting a variety of sources such as leached plant material, organic matter from surrounding soils, and microbial processes in the streams themselves. Headwater perennial streams in the Tuckahoe Creek watershed of the Atlantic coastal plain (Maryland, USA) drain a mosaic of land cover types including row crops, forests, and both forested and marshy small depressional wetlands. Wetland-stream surface hydrologic connections generally occur between mid-fall and late spring, coinciding with peak wetland hydrologic expression (i.e. highest groundwater levels and surface inundation extent). When inundated, these wetlands contain high DOM concentrations, and surface connections may serve as conduits for downstream export. We hypothesized that changes in wetland-stream surface hydrologic connectivity would affect patterns of DOM concentration and composition in these streams. We deployed 6 sondes equipped with fluorescent DOM sensors in 4 perennial streams, 1 forested wetland, and the larger downstream channel draining all study sites for the 2015 water year. The 4 headwater streams drain areas containing forested wetlands and have documented temporary channel connections. Combined with baseflow and stormflow sampling, the sondes provided 15 minute estimates of dissolved organic carbon (DOC) concentrations. This resolution provided insights into patterns of DOC concentration across temporal scales from daily rhythms to seasonal changes, during both baseflow and storm conditions. Discrete measurements of absorbance and fluorescence provided information about DOM composition throughout the study. Together these measurements give a detailed record of DOM dynamics in multiple perennial headwater streams for an entire year. This information

  12. Denitrification potential in sediments of headwater streams in the southern appalachian mountains, USA

    Science.gov (United States)

    Lara A. Martin; Patrick J. Mulholland; Jackson R. Webster; H. Maurice Vallett

    2001-01-01

    We investigated variations in resource availability (NOa-N and labile organic C [LOCJ] as determinants of potential denitrification in stream sediments in the southern Appalachian Mountains, USA. stream-water and sediments were sampled seasonally in 2 streams of contrasting NO3,-N availability, Noland Creek (high NO

  13. Landscape Characteristics and Variations in Longitudinal Stream Flow Contribution in two Headwater Semi-Arid Mountain Watersheds

    Science.gov (United States)

    Shakespeare, B.; Gooseff, M. N.

    2005-12-01

    Understanding what role particular catchment attributes (slope, aspect, landcover, and contributing area) play in the contribution of stream flow is important for land management decisions, especially in the semi-arid western areas of the United States. Our study site is paired small catchments (approximately 9 and 11 km2) in the headwaters of the Weber drainage basin in Northern Utah. These catchments are surrounded by Wasatch formation with loamy textured soils. One catchment is predominantly underlain by quartzite while the other catchment is mostly underlain by limestone. We measured lateral flow gains every 200 to 400 meters using salt dilution gauging techniques throughout the ~5 km long streams. These measurements were taken synoptically 3 times during the seasonal discharge recession (summer 2005). The flows ranged spatially from 4 L s-1 to 55 L s-1 and varied temporally by as much as 50% when comparing the same reaches. Using GIS software, landscape analysis of slope, aspect, contributing area, topographic convergence, riparian and hillslope area, and landcover was performed for each of the delineated stream reach contributing areas. The results were tested for correlations between lateral flow gains measured in the field and different landscape characteristics. Each of the synoptic events was compared with each other to explore effects of seasonal recession on the relationships between flow gain and landscape characteristics.

  14. A mechanistic assessment of seasonal microhabitat selection by drift-feeding rainbow trout Oncorhynchus mykiss in a southwestern headwater stream

    Science.gov (United States)

    Kalb, Bradley W.; Huntsman, Brock M.; Caldwell, Colleen A.; Bozek, Michael A.

    2018-01-01

    The positioning of fishes within a riverscape is dependent on the proximity of complementary habitats. In this study, foraging and non-foraging habitat were quantified monthly over an entire year for a rainbow trout (Oncorhynchus mykiss) population in an isolated, headwater stream in southcentral New Mexico. The stream follows a seasonal thermal and hydrologic pattern typical for a Southwestern stream and was deemed suitable for re-introduction of the native and close relative, Rio Grande cutthroat trout (O. clarkii virginalis). However, uncertainty associated with limited habitat needed to be resolved if repatriation of the native fish was to be successful. Habitat was evaluated using resource selection functions with a mechanistic drift-foraging model to explain trout distributions. Macroinvertebrate drift was strongly season- and temperature-dependent (lower in winter and spring, higher in summer and fall). Models identified stream depth as the most limiting factor for habitat selection across seasons and size-classes. Additionally, positions closer to cover were selected during the winter by smaller size-classes (0, 1, 2), while net energy intake was important during the spring for most size-classes (0, 1, 2, 3). Drift-foraging models identified that 81% of observed trout selected positions that could meet maintenance levels throughout the year. Moreover, 40% of selected habitats could sustain maximum growth. Stream positions occupied by rainbow trout were more energetically profitable than random sites regardless of season or size-class. Larger size-classes (3, 4+) were energetically more limited throughout the year than were smaller size-classes. This research suggests that habitat in the form of deep pools is of paramount importance for rainbow trout or native cutthroat trout.

  15. Flood-hazard analysis of four headwater streams draining the Argonne National Laboratory property, DuPage County, Illinois

    Science.gov (United States)

    Soong, David T.; Murphy, Elizabeth A.; Straub, Timothy D.; Zeeb, Hannah L.

    2016-11-22

    Results of a flood-hazard analysis conducted by the U.S. Geological Survey, in cooperation with the Argonne National Laboratory, for four headwater streams within the Argonne National Laboratory property indicate that the 1-percent and 0.2-percent annual exceedance probability floods would cause multiple roads to be overtopped. Results indicate that most of the effects on the infrastructure would be from flooding of Freund Brook. Flooding on the Northeast and Southeast Drainage Ways would be limited to overtopping of one road crossing for each of those streams. The Northwest Drainage Way would be the least affected with flooding expected to occur in open grass or forested areas.The Argonne Site Sustainability Plan outlined the development of hydrologic and hydraulic models and the creation of flood-plain maps of the existing site conditions as a first step in addressing resiliency to possible climate change impacts as required by Executive Order 13653 “Preparing the United States for the Impacts of Climate Change.” The Hydrological Simulation Program-FORTRAN is the hydrologic model used in the study, and the Hydrologic Engineering Center‒River Analysis System (HEC–RAS) is the hydraulic model. The model results were verified by comparing simulated water-surface elevations to observed water-surface elevations measured at a network of five crest-stage gages on the four study streams. The comparison between crest-stage gage and simulated elevations resulted in an average absolute difference of 0.06 feet and a maximum difference of 0.19 feet.In addition to the flood-hazard model development and mapping, a qualitative stream assessment was conducted to evaluate stream channel and substrate conditions in the study reaches. This information can be used to evaluate erosion potential.

  16. Stream biofilm responses to flow intermittency: from cells to ecosystems

    OpenAIRE

    Sergi eSabater; Sergi eSabater; Xisca eTimoner; Carles eBorrego; Carles eBorrego; Vicenç eAcuña

    2016-01-01

    Temporary streams are characterized by the alternation of dry and wet hydrological phases, creating both a harsh environment for the biota as well as a high diversity of opportunities for adaptation. These systems are eminently microbial-based during several of these hydrological phases, and those growing on all solid substrata (biofilms) accordingly change their physical structure and community composition. Biofilms experience large decreases on cell densities and biomass, both of bacteria a...

  17. Stream Biofilm Responses to Flow Intermittency: From Cells to Ecosystems

    OpenAIRE

    Sabater, Sergi; Timoner, Xisca; Borrego, Carles; Acuña, Vicenç

    2016-01-01

    Temporary streams are characterized by the alternation of dry and wet hydrological phases, creating both a harsh environment for the biota as well as a high diversity of opportunities for adaptation. These systems are mainly microbial-based during several of these hydrological phases, and those growing on all solid substrata (biofilms) accordingly change their physical structure and community composition. Biofilms experience large decreases in cell densities and biomass, both of bacteria and ...

  18. Effects of flow intermittency and pharmaceutical exposure on the structure and metabolism of stream biofilms.

    Science.gov (United States)

    Corcoll, Natàlia; Casellas, Maria; Huerta, Belinda; Guasch, Helena; Acuña, Vicenç; Rodríguez-Mozaz, Sara; Serra-Compte, Albert; Barceló, Damià; Sabater, Sergi

    2015-01-15

    Increasing concentrations of pharmaceutical compounds occur in many rivers, but their environmental risk remains poorly studied in stream biofilms. Flow intermittency shapes the structure and functions of ecosystems, and may enhance their sensitivity to toxicants. This study evaluates the effects of a long-term exposure of biofilm communities to a mixture of pharmaceutical compounds at environmental concentrations on biofilm bioaccumulation capacity, the structure and metabolic processes of algae and bacteria communities, and how their potential effects were enhanced or not by the occurrence of flow intermittency. To assess the interaction between those two stressors, an experiment with artificial streams was performed. Stream biofilms were exposed to a mixture of pharmaceuticals, as well as to a short period of flow intermittency. Results indicate that biofilms were negatively affected by pharmaceuticals. The algal biomass and taxa richness decreased and unicellular green algae relatively increased. The structure of the bacterial (based on denaturing gradient gel electrophoresis of amplified 16S rRNA genes) changed and showed a reduction of the operational taxonomic units (OTUs) richness. Exposed biofilms showed higher rates of metabolic processes, such as primary production and community respiration, attributed to pharmaceuticals stimulated an increase of green algae and heterotrophs, respectively. Flow intermittency modulated the effects of chemicals on natural communities. The algal community became more sensitive to short-term exposure of pharmaceuticals (lower EC50 value) when exposed to water intermittency, indicating cumulative effects between the two assessed stressors. In contrast to algae, the bacterial community became less sensitive to short-term exposure of pharmaceuticals (higher EC50) when exposed to water intermittency, indicating co-tolerance phenomena. According to the observed effects, the environmental risk of pharmaceuticals in nature is high

  19. Response of stream-breeding salamander larvae to sediment deposition in southern Appalachian (U.S.A.) headwater streams

    Science.gov (United States)

    S. Conner Keitzer; Reuben. Goforth

    2012-01-01

    Summary 1. Increased fine sediment deposition is a prevalent threat to stream biodiversity and has been shown to impact stream-breeding salamanders negatively. However, their complex life histories make it difficult to determine which stage is affected. 2. We conducted field experiments from 26 August to 11 September 2010 and 11 October to 11...

  20. Sensitivity of intermittent streams to climate variations in the western United States

    Science.gov (United States)

    Eng, K.; Wolock, D.; Dettinger, M. D.

    2014-12-01

    There is a great deal of interest in streamflow changes caused by climate change because of the potential negative effects on aquatic biota and water supplies. Most previous studies have focused on perennial streams, and only a few studies have examined the effect of climate variability on intermittent streams. Our objective in this study was to evaluate the sensitivity of intermittent streams to historical variability in climate in the semi-arid regions of the western United States. This study was carried out at 45 intermittent streams that had a minimum of 45 years of daily-streamgage record by evaluating: (1) correlations among time series of flow metrics (number of zero-flow events, the average of the central 50% and largest 10% of flows) with climate, and (2) decadal changes in the seasonality and long-term trends of these flow metrics. Results showed strong associations between the low-flow metrics and historical changes in climate. The decadal analysis, in contrast, suggested no significant seasonal shifts or decade-to-decade trends in the low-flow metrics. The lack of trends or changes in seasonality is likely due to unchanged long-term patterns in precipitation over the time period examined.

  1. Riparian influences on the biophysical characteristics of seston in headwater streams.

    Science.gov (United States)

    Scott R. Elliott; Robert J. Naiman; Peter A. Bisson

    2004-01-01

    Suspended particles (seston) in streams are an important source of nutrition for many invertebrates, forming a strong trophic link between plant and animal production. In forested regions the management of riparian corridors may alter alloehthonous and autochthonous contributions to streams, ultimately changing the biophysical characteristics of seston. This article...

  2. Assessing Impacts of Unconventional Natural Gas Extraction on Microbial Communities in Headwater Stream Ecosystems in Northwestern Pennsylvania

    Directory of Open Access Journals (Sweden)

    Ryan eTrexler

    2014-11-01

    Full Text Available Hydraulic fracturing and horizontal drilling have increased dramatically in Pennsylvania Marcellus shale formations, however the potential for major environmental impacts are still incompletely understood. High-throughput sequencing of the 16S rRNA gene was performed to characterize the microbial community structure of water, sediment, bryophyte, and biofilm samples from 26 headwater stream sites in northwestern Pennsylvania with different histories of fracking activity within Marcellus shale play. Further, we describe the relationship between microbial community structure and environmental parameters measured. Approximately 3.2 million 16S rRNA gene sequences were retrieved from a total of 58 samples. Microbial community analyses showed significant reductions in species richness as well as evenness in sites with Marcellus shale activity (MSA+. Beta diversity analyses revealed distinct microbial community structure between sites with and without Marcellus shale activity (MSA-. For example, OTUs within the Acetobacteracea, Methylocystaceae, Acidobacteriaceae, and Phenylobacterium were greater than three log-fold more abundant in MSA+ sites as compared to MSA- sites. Further, several of these OTUs were strongly negatively correlated with pH and positively correlated with the number of wellpads in a watershed. It should be noted that many of the OTUs enriched in MSA+ sites are putative acidophilic and/or methanotrophic populations. This study revealed apparent shifts in the autochthonous microbial communities and highlighted potential members that could be responding to changing stream conditions as a result of nascent industrial activity in these aquatic ecosystems.

  3. Assessing impacts of unconventional natural gas extraction on microbial communities in headwater stream ecosystems in Northwestern Pennsylvania

    Science.gov (United States)

    Trexler, Ryan; Solomon, Caroline; Brislawn, Colin J.; Wright, Justin R.; Rosenberger, Abigail; McClure, Erin E.; Grube, Alyssa M.; Peterson, Mark P.; Keddache, Mehdi; Mason, Olivia U.; Hazen, Terry C.; Grant, Christopher J.; Lamendella, Regina

    2014-01-01

    Hydraulic fracturing and horizontal drilling have increased dramatically in Pennsylvania Marcellus shale formations, however the potential for major environmental impacts are still incompletely understood. High-throughput sequencing of the 16S rRNA gene was performed to characterize the microbial community structure of water, sediment, bryophyte, and biofilm samples from 26 headwater stream sites in northwestern Pennsylvania with different histories of fracking activity within Marcellus shale formations. Further, we describe the relationship between microbial community structure and environmental parameters measured. Approximately 3.2 million 16S rRNA gene sequences were retrieved from a total of 58 samples. Microbial community analyses showed significant reductions in species richness as well as evenness in sites with Marcellus shale activity. Beta diversity analyses revealed distinct microbial community structure between sites with and without Marcellus shale activity. For example, operational taxonomic units (OTUs) within the Acetobacteracea, Methylocystaceae, Acidobacteriaceae, and Phenylobacterium were greater than three log-fold more abundant in MSA+ sites as compared to MSA− sites. Further, several of these OTUs were strongly negatively correlated with pH and positively correlated with the number of wellpads in a watershed. It should be noted that many of the OTUs enriched in MSA+ sites are putative acidophilic and/or methanotrophic populations. This study revealed apparent shifts in the autochthonous microbial communities and highlighted potential members that could be responding to changing stream conditions as a result of nascent industrial activity in these aquatic ecosystems. PMID:25408683

  4. Partitioning Hydrologic and Biological Drivers of Discharge Loss in Arctic Headwater Streams

    Science.gov (United States)

    Koch, J. C.; Carey, M.; O'Donnell, J. A.; Records, M. K.; Sjoberg, Y.; Zimmerman, C. E.

    2017-12-01

    The Arctic-Boreal transition (ABT) zone of Alaska is experiencing unprecedented warming, leading to permafrost thaw and vegetation change. Both of these processes are likely to affect streams and stream ecosystems, but there is little direct empirical evidence regarding the magnitude of these effects and their relative importance. To understand how permafrost thaw and vegetation are affecting streams at the ABT, we monitored 8 first-order streams that drain catchments varying in elevation, aspect, and vegetation cover. Data were obtained from meteorological stations, continuous stream discharge, seepage runs, and stream tracer experiments. Hydrograph analysis indicated that runoff ratios in south-facing catchments were lower than north-facing catchments and decreased over the season. Seepage runs indicated that south-facing catchments lost a large portion of water (up to 50% per km stream reach) in the late summer, while north-facing catchments were gaining water. All streams displayed diel variability in discharge, but with different daily and seasonal trends related to aspect and elevation. South-facing, forested catchment streams showed diel discharge timing consistent with cycles in evapotranspiration rates, while the signal in north-facing catchments and those dominated by tundra was more consistent with thermal controls on water viscosity and groundwater discharge to streams. Together, these signals indicate that the warmer, south-facing catchments are losing a large portion of water to a combination of infiltration and evapotranspiration. The seasonal trends are consistent with higher infiltration rates beneath south-facing streams as the ground thaws over the summer. The magnitude and seasonal dynamics of the diel signatures help separate biological (i.e. evapotranspiration) vs. physical controls (i.e. frozen ground hydrology) on stream-catchment interactions, which vary depending on aspect, elevation, and vegetation cover. Warming, and subsequent increases

  5. Macroinvertebrate Community Response to the Elimination of Concentrated Feedlot Runoff to a Headwater Stream

    Science.gov (United States)

    Snitgen, J. L.; Moren, M. M.

    2005-05-01

    During rainfall and snow melt events, a first order, cold-water stream was receiving varying amounts of liquefied manure from a concentrated feed lot. Stream restoration efforts included the implementation of best management practices to prevent further discharge of the water/manure mixture to the stream. Physical, chemical and biological data were collected pre-construction and two years post-construction of the containment system at a fixed location downstream of the feedlot. Hilsenhoff Biotic Index scores improved significantly, from 6.79 or "Fairly Poor" before the installation of the manure containment system, to 5.28 or "Good" after the installation of the manure containment system. Taxa richness improved from 25 to 34 and the EPT score improved from 0 to 4. Key words: macroinvertebrate, community response, manure, feedlot runoff, stream restoration

  6. Endogenous and exogenous control of ecosystem function: N cycling in headwater streams.

    Science.gov (United States)

    Valett, H M; Thomas, S A; Mulholland, P J; Webster, J R; Dahm, C N; Fellows, C S; Crenshaw, C L; Peterson, C G

    2008-12-01

    Allochthonous inputs act as resource subsidies to many ecosystems, where they exert strong influences on metabolism and material cycling. At the same time, metabolic theory proposes endogenous thermal control independent of resource supply. To address the relative importance of exogenous and endogenous influences, we quantified spatial and temporal variation in ecosystem metabolism and nitrogen (N) uptake using seasonal releases of 15N as nitrate in six streams differing in riparian-stream interaction and metabolic character. Nitrate removal was quantified using a nutrient spiraling approach based on measurements of downstream decline in 15N flux. Respiration (R) and gross primary production (GPP) were measured with whole-stream diel oxygen budgets. Uptake and metabolism metrics were addressed as z scores relative to site means to assess temporal variation. In open-canopied streams, areal uptake (U; microg N x m(-2) x s(-1)) was closely related to GPP, metabolic rates increased with temperature, and R was accurately predicted by metabolic scaling relationships. In forested streams, N spiraling was not related to GPP; instead, uptake velocity (v(f); mm/s) was closely related to R. In contrast to open-canopied streams, N uptake and metabolic activity were negatively correlated to temperature and poorly described by scaling laws. We contend that streams differ along a gradient of exogenous and endogenous control that relates to the relative influences of resource subsidies and in-stream energetics as determinants of seasonal patterns of metabolism and N cycling. Our research suggests that temporal variation in the propagation of ecological influence between adjacent systems generates phases when ecosystems are alternatively characterized as endogenously and exogenously controlled.

  7. Endogenous and exogenous control of ecosystem function: N cycling in headwater streams

    Energy Technology Data Exchange (ETDEWEB)

    Mulholland, Patrick J [ORNL; Valett, H. Maurice [Virginia Polytechnic Institute and State University (Virginia Tech); Thomas, Steve [University of Nebraska; Webster, Jackson [Virginia Polytechnic Institute and State University (Virginia Tech); Dahm, Cliff [University of New Mexico, Albuquerque; Fellows, Christine [Griffith University, Nathan, Queensland, Australia; Crenshaw, Chelsea [University of New Mexico, Albuquerque; Peterson, Chris G. [Loyola University

    2008-01-01

    Allochthonous inputs act as resource subsidies to many ecosystems, where they exert strong influences on metabolism and material cycling. At the same time, metabolic theory proposes endogenous thermal control independent of resource supply. To address the relative importance of exogenous and endogenous influences, we quantified spatial and temporal variation in ecosystem metabolism and nitrogen (N) uptake using seasonal releases of {sup 15}N as nitrate in six streams differing in riparian-stream interaction and metabolic character. Nitrate removal was quantified using a nutrient spiraling approach based on measurements of downstream decline in {sup 15}N flux. Respiration (R) and gross primary production (GPP) were measured with whole-stream diel oxygen budgets. Uptake and metabolism metrics were addressed as z scores relative to site means to assess temporal variation. In open-canopied streams, areal uptake (U; {micro}g N {center_dot} m{sup -2} {center_dot} s{sup -1}) was closely related to GPP, metabolic rates increased with temperature, and R was accurately predicted by metabolic scaling relationships. In forested streams, N spiraling was not related to GPP; instead, uptake velocity (v{sub f}; mm/s) was closely related to R. In contrast to open-canopied streams, N uptake and metabolic activity were negatively correlated to temperature and poorly described by scaling laws. We contend that streams differ along a gradient of exogenous and endogenous control that relates to the relative influences of resource subsidies and in-stream energetics as determinants of seasonal patterns of metabolism and N cycling. Our research suggests that temporal variation in the propagation of ecological influence between adjacent systems generates phases when ecosystems are alternatively characterized as endogenously and exogenously controlled.

  8. Endogenous and exogenous control of ecosystem function: N cycling in headwater streams

    OpenAIRE

    Valett, H. M.; Thomas, S. A.; Mulholland, P. J.; Webster, J. R.; Dahm, C. N.; Fellows, C. S.; Crenshaw, C. L.; Peterson, C. G.

    2008-01-01

    Allochthonous inputs act as resource subsidies to many ecosystems, where they exert strong influences on metabolism and material cycling. At the same time, metabolic theory proposes endogenous thermal control independent of resource supply. To address the relative importance of exogenous and endogenous influences, we quantified spatial and temporal variation in ecosystem metabolism and nitrogen (N) uptake using seasonal releases of (15)N as nitrate in six streams differing in riparian-stream ...

  9. Influence of Pools and Riffles on Chironomidae Diversity in Headwater Streams of the Atlantic Forest.

    Science.gov (United States)

    Silveira, L S; Rosa, B F J V; Gonçalves, E A; Alves, R G

    2015-10-01

    Studies on mesohabitat scale have been used to shed light on the ecology and distribution of chironomid larvae in small streams. Thus, the objective of the present study was to examine the diversity and distribution of the Chironomidae assemblage on the mesohabitat scale in three streams located in different preserved areas of southeastern Brazil. In each stream, litter samples were obtained in the dry season of 2010 in ten pools and ten riffles with a Surber sampler (area 0.04 m(2); mesh size 0.21 mm). The abundance was similar among streams and between mesohabitats, while the estimated richness was highest in riffles. There was a difference in the composition of the Chironomidae assemblages between the mesohabitats, although the litter composition was similar between them, indicating the importance of current speed on the distribution of the taxa. The dispersion of the sample units (β-diversity) of riffles and pools was similar, although it was different among the three streams. The results of this study provide further evidence of the importance of habitat heterogeneity within streams as a generator of diversity for Chironomidae in tropical lotic systems.

  10. Nitrogen and phosphorus uptake in two Idaho (USA) headwater wilderness streams.

    Science.gov (United States)

    Davis, Jeffrey C; Minshall, G Wayne

    1999-05-01

    Nitrate and phosphate solutions were released into two reaches of two central Idaho streams to determine within- and between-stream variability in uptake lengths, uptake rates, and mass transfer coefficients. Physical and biotic stream characteristics and periphyton nitrate-uptake rates in recirculating chambers were measured to determine their influence on nutrient dynamics. Phosphate uptake length did not differ among the four reaches. There were no within-stream differences in nitrate uptake lengths but they did differ between the two streams. Long nitrate uptake lengths likely were due to instream concentrations above saturation but also may have been influenced by differences in active surface area and algal abundance. Nitrate and phosphate uptake lengths were longer, and uptake rates higher, than most other published values. However, mass transfer coefficients were comparable to measurements in other streams. Mass transfer coefficients may be a better parameter for temporal and spatial comparisons of instream nutrient dynamics, and for determining the underlying causes of variability in uptake length.

  11. Small but powerful: top predator local extinction affects ecosystem structure and function in an intermittent stream.

    Science.gov (United States)

    Rodríguez-Lozano, Pablo; Verkaik, Iraima; Rieradevall, Maria; Prat, Narcís

    2015-01-01

    Top predator loss is a major global problem, with a current trend in biodiversity loss towards high trophic levels that modifies most ecosystems worldwide. Most research in this area is focused on large-bodied predators, despite the high extinction risk of small-bodied freshwater fish that often act as apex consumers. Consequently, it remains unknown if intermittent streams are affected by the consequences of top-predators' extirpations. The aim of our research was to determine how this global problem affects intermittent streams and, in particular, if the loss of a small-bodied top predator (1) leads to a 'mesopredator release', affects primary consumers and changes whole community structures, and (2) triggers a cascade effect modifying the ecosystem function. To address these questions, we studied the top-down effects of a small endangered fish species, Barbus meridionalis (the Mediterranean barbel), conducting an enclosure/exclosure mesocosm experiment in an intermittent stream where B. meridionalis became locally extinct following a wildfire. We found that top predator absence led to 'mesopredator release', and also to 'prey release' despite intraguild predation, which contrasts with traditional food web theory. In addition, B. meridionalis extirpation changed whole macroinvertebrate community composition and increased total macroinvertebrate density. Regarding ecosystem function, periphyton primary production decreased in apex consumer absence. In this study, the apex consumer was functionally irreplaceable; its local extinction led to the loss of an important functional role that resulted in major changes to the ecosystem's structure and function. This study evidences that intermittent streams can be affected by the consequences of apex consumers' extinctions, and that the loss of small-bodied top predators can lead to large ecosystem changes. We recommend the reintroduction of small-bodied apex consumers to systems where they have been extirpated, to restore

  12. Small but powerful: top predator local extinction affects ecosystem structure and function in an intermittent stream.

    Directory of Open Access Journals (Sweden)

    Pablo Rodríguez-Lozano

    Full Text Available Top predator loss is a major global problem, with a current trend in biodiversity loss towards high trophic levels that modifies most ecosystems worldwide. Most research in this area is focused on large-bodied predators, despite the high extinction risk of small-bodied freshwater fish that often act as apex consumers. Consequently, it remains unknown if intermittent streams are affected by the consequences of top-predators' extirpations. The aim of our research was to determine how this global problem affects intermittent streams and, in particular, if the loss of a small-bodied top predator (1 leads to a 'mesopredator release', affects primary consumers and changes whole community structures, and (2 triggers a cascade effect modifying the ecosystem function. To address these questions, we studied the top-down effects of a small endangered fish species, Barbus meridionalis (the Mediterranean barbel, conducting an enclosure/exclosure mesocosm experiment in an intermittent stream where B. meridionalis became locally extinct following a wildfire. We found that top predator absence led to 'mesopredator release', and also to 'prey release' despite intraguild predation, which contrasts with traditional food web theory. In addition, B. meridionalis extirpation changed whole macroinvertebrate community composition and increased total macroinvertebrate density. Regarding ecosystem function, periphyton primary production decreased in apex consumer absence. In this study, the apex consumer was functionally irreplaceable; its local extinction led to the loss of an important functional role that resulted in major changes to the ecosystem's structure and function. This study evidences that intermittent streams can be affected by the consequences of apex consumers' extinctions, and that the loss of small-bodied top predators can lead to large ecosystem changes. We recommend the reintroduction of small-bodied apex consumers to systems where they have been

  13. Influence of shredder feeding and nutrients on fungal activity and community structure in headwater streams

    Science.gov (United States)

    Namil Chung; Keller. Suberkropp

    2008-01-01

    In stream detrital food webs, interactions occur between aquatic hyphomycetes associated with decomposing leaves and shredders consuming those leaves. However, few studies have examined how the feeding activity of shredders affects aquatic hyphomycetes. We examined the effect of shredder feeding on aquatic hyphomycete communities associated with submerged leaves in two...

  14. Distance, flow and PCR inhibition: eDNA dynamics in two headwater streams

    Science.gov (United States)

    Stephen F. Jane; Taylor M. Wilcox; Kevin S. McKelvey; Michael K. Young; Michael K. Schwartz; Winsor H. Lowe; Benjamin H. Letcher; Andrew R. Whiteley

    2014-01-01

    Environmental DNA (eDNA) detection has emerged as a powerful tool for monitoring aquatic organisms, but much remains unknown about the dynamics of aquatic eDNA over a range of environmental conditions. DNA concentrations in streams and rivers will depend not only on the equilibrium between DNA entering the water and DNA leaving the system through degradation, but also...

  15. Quantifying the production of dissolved organic nitrogen in headwater streams using 15N tracer additions

    Science.gov (United States)

    Laura T. Johnson; Jennifer L. Tank; Robert O. Hall; Patrick J. Mullholland; Stephen K. Hamilton; H. Maurice Valett; Jackson R. Webster; Melody J. Bernot; William H. McDowell; Bruce J. Peterson; Suzanne M. Thomas

    2013-01-01

    Most nitrogen (N) assimilation in lake and marine ecosystems is often subsequently released via autochthonous dissolved organic nitrogen (DON) production, but autochthonous DON production has yet to be quantified in flowing waters. We measured in-stream DON production following 24 h 15N-nitrate (NO3-...

  16. Controls on stream water dissolved mercury in three mid-Appalachian forested headwater catchments

    Science.gov (United States)

    Riscassi, Ami L.; Scanlon, Todd M.

    2011-12-01

    Determining the controls on dissolved mercury (HgD) transport is necessary to improve estimations of export from unmonitored watersheds and to forecast responses to changes in deposition and other environmental forcings. Stream water HgD and dissolved organic carbon (DOC) were evaluated over a range of discharge conditions in three streams within Shenandoah National Park, VA. Watersheds are distinguished by stream water pH (ranging from neutral to acidic) and soil size fractioning (ranging from clays to sands). At all sites, discharge was a significant but poor predictor of HgD concentrations (r2 from 0.13-0.52). HgD was strongly coupled with DOC at all sites (r2 from 0.74-0.89). UV absorbance at 254 nm (UV254), a proxy for DOC quantity and quality, slightly improved the predictions of HgD. Mean DOC quality differed between streams, with less aromatic DOC mobilized from the more acidic watershed. The site with less aromatic DOC and sandy soils mobilized more Hg to the stream for the same quantity and quality of DOC, likely due to the reduced capacity of the larger-grained soils to retain Hg, leaving a greater fraction associated with the organic matter. A similar amount of 0.54 ng HgD/mg DOC is transported at all sites, suggesting the less aromatic DOC transports less Hg per unit DOC, offsetting the effects of soil type. This research demonstrates that soil composition and DOC quality influence HgDexport. We also provide evidence that soil organic carbon is a primary control on Hg-DOC ratios (0.12-1.4 ng mg-1) observed across the U.S. and Sweden.

  17. Potential population and assemblage influences of non-native trout on native nongame fish in Nebraska headwater streams

    Science.gov (United States)

    Turek, Kelly C.; Pegg, Mark A.; Pope, Kevin L.; Schainost, Steve

    2014-01-01

    Non-native trout are currently stocked to support recreational fisheries in headwater streams throughout Nebraska. The influence of non-native trout introductions on native fish populations and their role in structuring fish assemblages in these systems is unknown. The objectives of this study were to determine (i) if the size structure or relative abundance of native fish differs in the presence and absence of non-native trout, (ii) if native fish-assemblage structure differs in the presence and absence of non-native trout and (iii) if native fish-assemblage structure differs across a gradient in abundances of non-native trout. Longnose dace Rhinichthys cataractae were larger in the presence of brown trout Salmo trutta and smaller in the presence of rainbow trout Oncorhynchus mykiss compared to sites without trout. There was also a greater proportion of larger white suckers Catostomus commersonii in the presence of brown trout. Creek chub Semotilus atromaculatus and fathead minnow Pimephales promelas size structures were similar in the presence and absence of trout. Relative abundances of longnose dace, white sucker, creek chub and fathead minnow were similar in the presence and absence of trout, but there was greater distinction in native fish-assemblage structure between sites with trout compared to sites without trout as trout abundances increased. These results suggest increased risk to native fish assemblages in sites with high abundances of trout. However, more research is needed to determine the role of non-native trout in structuring native fish assemblages in streams, and the mechanisms through which introduced trout may influence native fish populations.

  18. Quantifying ratios of suspended sediment sources in forested headwater streams following timber-harvesting operations

    Science.gov (United States)

    Rachels, A. A.; Bladon, K. D.; Bywater-Reyes, S.

    2017-12-01

    Historically, timber-harvesting has increased fine sediment inputs to streams due to increased hillslope and streambank erosion and mass wasting along roads. However, under modern best management practices, the relative importance and variability of these sources is poorly understood. We present preliminary results from an ongoing study investigating the primary sources of suspended sediment in Oregon Coast Range streams influenced by timber harvesting. We instrumented two catchments, Enos Creek (harvested 2016) and Scheele Creek (reference) in fall 2016. Phillips samplers (5-6 per catchment) have been deployed longitudinally down the streams to enable robust characterization of suspended sediments—the collected samples integrate the chemical signatures of upstream sediment exports. We will collect samples monthly over 2 wet seasons and return to the laboratory to analyze the sediment using source fingerprinting approaches. The fingerprinting technique compares the chemical properties of stream sediment samples with the chemical properties of potential source areas, including 1) roads, 2) stream banks, and 3) hillslopes. To design a robust model for sediment-source identification, different types of chemical data are required—we will analyze sediment samples using a combination of: a) stable isotopes and C/N ratios (i.e., δ15N, δ13C, and C/N), b) geochemistry (Fe, K, and Ca), and c) radiogenic isotopes (137Cs and 210Pb). At the harvested site, the C/N ratios of the streambanks (17.9 ± 3.8) and the hillslopes (26.4 ± 4.8) are significantly different from one another (p = .016). C/N ratios of the suspended sediment (20.5 ± 2.0) are intermediate values between potential endmembers and behave conservatively with transport. The C/N ratios of the suspended sediment appear unaffected by roads (18.9 ± 8.7) along specific sections of the stream, suggesting that roads are not a primary sediment contributor. Under this assumption, the suspended sediment is, on

  19. DOC:NO3- ratios and NO3- uptake in forested headwater streams

    Science.gov (United States)

    Rodríguez-Cardona, Bianca; Wymore, Adam S.; McDowell, William H.

    2016-01-01

    The underlying mechanisms driving the coupled interactions between inorganic nitrogen uptake and dissolved organic matter are not well understood, particularly in surface waters. To determine the relationship between dissolved organic carbon (DOC) quantity and nitrate (NO3-) uptake kinetics in streams, we performed a series of NO3- Tracer Additions for Spiraling Curve Characterization experiments in four streams within the Lamprey River Watershed, New Hampshire, across a range in background DOC concentrations (1-8 mg C/L). Experiments were performed throughout the 2013 and 2014 growing seasons. Across streams and experimental dates, ambient uptake velocity (Vf) correlated positively with increasing DOC concentrations and DOC:NO3- ratios but was only weakly negatively associated with NO3- concentrations. Ambient NO3- Vf was unrelated to pH, light, temperature, dissolved oxygen, and Specific Ultraviolet Absorbance at 254 nm. Although there were general tendencies across the entire Lamprey River Watershed, individual sites behaved differently in their uptake kinetics. NO3- uptake dynamics in the Lamprey River Watershed are most strongly influenced by DOC concentrations rather than NO3- concentrations or physicochemical parameters, which have been identified as regional- to continental-scale drivers in previous research. Understanding the fundamental relationships between dissolved organic matter and inorganic nutrients will be important as global and climatic changes influence the delivery and production of DOC and NO3- in aquatic ecosystems.

  20. A detailed risk assessment of shale gas development on headwater streams in the Pennsylvania portion of the Upper Susquehanna River Basin, U.S.A.

    Science.gov (United States)

    Maloney, Kelly O.; Young, John A.; Faulkner, Stephen; Hailegiorgis, Atesmachew; Slonecker, E. Terrence; Milheim, Lesley

    2018-01-01

    The development of unconventional oil and gas (UOG) involves infrastructure development (well pads, roads and pipelines), well drilling and stimulation (hydraulic fracturing), and production; all of which have the potential to affect stream ecosystems. Here, we developed a fine-scaled (1:24,000) catchment-level disturbance intensity index (DII) that included 17 measures of UOG capturing all steps in the development process (infrastructure, water withdrawals, probabilistic spills) that could affect headwater streams (pipeline cover, road cover and well pad cover metrics. We related this DII to three measures of high quality streams: Pennsylvania State Exceptional Value (EV) streams, Class A brook trout streams and Eastern Brook Trout Joint Venture brook trout patches. Overall only 3.8% of all catchments and 2.7% of EV stream length, 1.9% of Class A streams and 1.2% of patches were classified as having medium to high level DII scores (> 50). Well density, often used as a proxy for development, only correlated strongly with well pad coverage and produced materials, and therefore may miss potential effects associated with roads and pipelines, water withdrawals and spills. When analyzed with a future development scenario, 91.1% of EV stream length, 68.7% of Class A streams and 80.0% of patches were in catchments with a moderate to high probability of development. Our method incorporated the cumulative effects of UOG on streams and can be used to identify catchments and reaches at risk to existing stressors or future development.

  1. Leaf litter processing and invertebrate assemblages along a pollution gradient in a Maine (USA) headwater stream

    International Nuclear Information System (INIS)

    Woodcock, Thomas S.; Huryn, Alexander D.

    2005-01-01

    During the autumn of 1997 and 1998, leaf litter processing rates and leaf pack invertebrate assemblages were examined at eight stations along a pollution gradient in Goosefare Brook, a first-order coastal plain stream in southern Maine (USA). There was no significant effect on litter softening rate in 1997, and only the most polluted station showed a decrease in 1998. However, litter loss rates showed decreases in both years. The structure of invertebrate assemblages changed in response to the stresses, showing a decline in EPT richness and an increase in the proportion of collecting taxa. However, total shredder biomass was only weakly affected. Shredder biomass at all stations was dominated by Tipula, and biomass of other shredder taxa showed a serial replacement along the gradient of stress related to their pollution tolerance. Rather than the expected relationship with shredder biomass, litter processing rates were directly related to water and sediment quality. Goosefare Brook demonstrates how variable pollution tolerance of community members enables stress resistance and a consequent preservation of ecosystem function. - Variable pollution tolerance of community members provides stress resistance at the ecosystem level in streams

  2. The biogeochemical fingerprint of urbanization: increasing carbon quality in Maine headwater streams

    Science.gov (United States)

    Parr, T.; Cronan, C.; Ohno, T.; Simon, K. S.

    2012-12-01

    Conversion of land cover to urban use is an accelerating global phenomenon. Physical landscape change manifests as the replacement of forests, grasslands, and wetlands with buildings, novel vegetation, and infrastructure. This physical change also brings with it a change in the human management of the landscape for aesthetic and practical purposes (i.e. road salt applications). Although urbanization's effects on inorganic nutrients have been well studied, far less is known about the interactive influences of urbanization and urban landscape management practices on dissolved organic matter (DOM), a key energy source essential to ecosystem function. We examined the seasonal abundance and composition of DOM, nutrients, and common cations in 116 small streams along a gradient of urbanization (0-60% total watershed imperviousness, TWI), in Maine, USA. Dissolved organic carbon concentration ranged from 0.5 to 20 ppm with no clear relationship to watershed urbanization. In contrast, DOM composition, quantified with specific ultra violet absorbance at 254 nm (SUVA_{254}), fluorescence indices, and parallel factor analysis (PARAFAC), changed considerably with increasing urbanization. SUVA_{254} indicated a shift from higher molecular weight humic compounds (SUVA_{254}>4) toward lower molecular weight compounds (SUVA_{254}road salt application may mobilize base cations into streams draining urbanized watersheds. There was a strong negative relationship between humic-like DOM components and Ca^{2+} (R^2=0.3-0.5, psalts over a natural range (0 - 6 mM) showed that ^{2+} cations (esp. Ca^{2+}) preferentially flocculated the humic fraction of DOM (R^2=0.6-0.9, premoving terrestrial C from the aquatic DOM pool in urban landscapes.

  3. Agricultural herbicide transport in a first-order intermittent stream, Nebraska, USA

    Science.gov (United States)

    Vogel, J.R.; Linard, J.I.

    2011-01-01

    The behavior of herbicides in surface waters is a function of many variables, including scale of the watershed, physical and chemical properties of the herbicide, physical and chemical properties of the soil, rainfall intensity, and time of year. In this study, the transport of 6 herbicides and 12 herbicide degradates was examined during the 2004 growing season in an intermediate-scale agricultural watershed (146 ha) that is drained by a first-order intermittent stream, and the mass load for each herbicide in the stream was estimated. The herbicide load during the first week of storm events after application ranged from 17% of annual load for trifluralin to 84% of annual load for acetochlor. The maximum weekly herbicide load in the stream was generally within the first 3 weeks after application for those compounds that were applied within the watershed during 2004, and later for herbicides not applied within the watershed during 2004 but still detected in the stream. The apparent dominant mode of herbicide transport in the stream-determined by analysis amongst herbicide and conservative ion concentrations at different points in the hydrograph and in base flow samples-was either overland runoff or shallow subsurface flow, depending on the elapsed time after application and type of herbicide. The load as a percentage of use (LAPU) for the parent compounds in this study was similar to literature values for those compounds applied by the farmer within the watershed, but smaller for those herbicides that had rainfall as their only source within the watershed.

  4. Alternative responses to predation in two headwater stream minnows is reflected in their contrasting diel activity patterns.

    Science.gov (United States)

    Kadye, Wilbert T; Booth, Anthony J

    2014-01-01

    Animals exhibit diel periodicity in their activity in part to meet energy requirements whilst evading predation. A competing hypothesis suggests that partitioning of diel activities is less important because animals capitalise on opportunity. To test these hypotheses we examined the diel activity patterns for two cyprinid minnows, chubbyhead barb Barbus anoplus and the Eastern Cape redfin minnow Pseudobarbus afer that both occur within headwater streams in the Eastern Cape, South Africa. Chubbyhead barbs exhibited consistent nocturnal activity based on both field and laboratory observations. Due to the absence of fish predators within its habitat, its nocturnal behaviour suggests a response to the cost associated with diurnal activity, such as predation risk by diving and wading birds. In contrast, redfin minnows showed high diurnal activity and a shoaling behaviour in the wild, whereas, in the laboratory, they showed high refuge use during the diel cycle. Despite their preference for refuge in the laboratory, they were diurnally active, a behaviour that was consistent with observations in the wild. The diurnal activity of this species suggests a response to the cost associated with nocturnal activity. Such a cost could be inferred from the presence of the longfin eel, a native predator that was active at night, whereas the daytime shoaling behaviour suggests an anti-predator mechanism to diurnal visual predators. The implications of these findings relate to the impacts associated with the potential invasions by non-native piscivores that occur in the mainstem sections. Diurnal activity patterns for redfin minnows, that are IUCN-listed as endangered, may, in part, explain their susceptibility to high predation by visual non-native piscivores, such as bass and trout. In contrast, the nocturnal habits of chubbyhead barbs suggest a probable pre-adaptation to visual predation. The likelihood of invasion by nocturnally-active sharptooth catfish Clarias gariepinus

  5. Alternative responses to predation in two headwater stream minnows is reflected in their contrasting diel activity patterns.

    Directory of Open Access Journals (Sweden)

    Wilbert T Kadye

    Full Text Available Animals exhibit diel periodicity in their activity in part to meet energy requirements whilst evading predation. A competing hypothesis suggests that partitioning of diel activities is less important because animals capitalise on opportunity. To test these hypotheses we examined the diel activity patterns for two cyprinid minnows, chubbyhead barb Barbus anoplus and the Eastern Cape redfin minnow Pseudobarbus afer that both occur within headwater streams in the Eastern Cape, South Africa. Chubbyhead barbs exhibited consistent nocturnal activity based on both field and laboratory observations. Due to the absence of fish predators within its habitat, its nocturnal behaviour suggests a response to the cost associated with diurnal activity, such as predation risk by diving and wading birds. In contrast, redfin minnows showed high diurnal activity and a shoaling behaviour in the wild, whereas, in the laboratory, they showed high refuge use during the diel cycle. Despite their preference for refuge in the laboratory, they were diurnally active, a behaviour that was consistent with observations in the wild. The diurnal activity of this species suggests a response to the cost associated with nocturnal activity. Such a cost could be inferred from the presence of the longfin eel, a native predator that was active at night, whereas the daytime shoaling behaviour suggests an anti-predator mechanism to diurnal visual predators. The implications of these findings relate to the impacts associated with the potential invasions by non-native piscivores that occur in the mainstem sections. Diurnal activity patterns for redfin minnows, that are IUCN-listed as endangered, may, in part, explain their susceptibility to high predation by visual non-native piscivores, such as bass and trout. In contrast, the nocturnal habits of chubbyhead barbs suggest a probable pre-adaptation to visual predation. The likelihood of invasion by nocturnally-active sharptooth catfish

  6. Benthic algae stimulate leaf litter decomposition in detritus-based headwater streams: a case of aquatic priming effect?

    Science.gov (United States)

    Danger, Michael; Cornut, Julien; Chauvet, Eric; Chavez, Paola; Elger, Arnaud; Lecerf, Antoine

    2013-07-01

    In detritus-based ecosystems, autochthonous primary production contributes very little to the detritus pool. Yet primary producers may still influence the functioning of these ecosystems through complex interactions with decomposers and detritivores. Recent studies have suggested that, in aquatic systems, small amounts of labile carbon (C) (e.g., producer exudates), could increase the mineralization of more recalcitrant organic-matter pools (e.g., leaf litter). This process, called priming effect, should be exacerbated under low-nutrient conditions and may alter the nature of interactions among microbial groups, from competition under low-nutrient conditions to indirect mutualism under high-nutrient conditions. Theoretical models further predict that primary producers may be competitively excluded when allochthonous C sources enter an ecosystem. In this study, the effects of a benthic diatom on aquatic hyphomycetes, bacteria, and leaf litter decomposition were investigated under two nutrient levels in a factorial microcosm experiment simulating detritus-based, headwater stream ecosystems. Contrary to theoretical expectations, diatoms and decomposers were able to coexist under both nutrient conditions. Under low-nutrient conditions, diatoms increased leaf litter decomposition rate by 20% compared to treatments where they were absent. No effect was observed under high-nutrient conditions. The increase in leaf litter mineralization rate induced a positive feedback on diatom densities. We attribute these results to the priming effect of labile C exudates from primary producers. The presence of diatoms in combination with fungal decomposers also promoted decomposer diversity and, under low-nutrient conditions, led to a significant decrease in leaf litter C:P ratio that could improve secondary production. Results from our microcosm experiment suggest new mechanisms by which primary producers may influence organic matter dynamics even in ecosystems where autochthonous

  7. Seasonal variability in nitrate and phosphate uptake kinetics in a forested headwater stream using pulse nutrient additions

    Science.gov (United States)

    Griffiths, N. A.; Mulholland, P. J.

    2011-12-01

    We used the Tracer Additions for Spiraling Curve Characterization (TASCC) approach to quantify seasonal variability in ambient nutrient spiraling metrics and nutrient uptake kinetics in the West Fork of Walker Branch, a forested headwater stream in eastern Tennessee, USA. We performed instantaneous additions of nitrate (NO3-) and phosphate (PO4-3) separately with a conservative tracer (chloride, Cl-) during the following biologically-important time periods: autumn (during leaf fall, high organic matter [OM] standing stocks), winter (low OM standing stocks), spring (prior to canopy closure), and summer (closed canopy). We predicted that nutrient demand would be highest during autumn and spring, as OM inputs fuel heterotrophic respiration and high light availability stimulates autotrophic production, respectively. The measured ambient PO4-3 uptake rates (Vf-amb) followed our predictions, with the highest Vf-amb rates in autumn (Vf-amb = 2.8 mm/min) and spring (Vf-amb = 2.9 mm/min), and undetectable uptake in winter. Further, maximum areal PO4-3 uptake rates (Umax) were higher in autumn (Umax = 297 μg/m2/min) than spring (Umax = 106 μg/m2/min), possibly due to greater nutrient demand of heterotrophs on leaf litter accumulations. Contrary to our predictions, ambient NO3- uptake rates were highest in autumn and winter (autumn: Vf-amb = 2.8 mm/min, winter: Vf-amb = 2.4 mm/min), and lowest in spring (Vf-amb = 1.0 mm/min). The higher than expected Vf-amb rate in winter may be due to higher stream metabolism rates and thus greater nitrogen demand; the lower than expected Vf-amb rate in spring may reflect an alleviation of nitrogen demand due to high ammonium concentrations during this time. As the demand for both nitrogen and phosphorus in Walker Branch is greatest in autumn, future work will characterize how nutrient metrics change during this dynamic time period (i.e., before, during, and after leaf fall).

  8. Distribution of mercury, Cesium-137, and plutonium in an intermittent stream at Los Alamos

    International Nuclear Information System (INIS)

    Hakonson, T.E.; White, G.C.; Gladney, E.S.; Dreicer, M.

    1980-01-01

    The results of a study on the distribution of Hg, 137 Cs, 238 Pu, and 239 240 Pu in channel sediments and adjacent bank soils in an intermittent stream used for treated liquid effluent disposal since 1963 are summarized. Concentrations of the three radionuclides and Hg in stream bank soils were comparable to adjacent channel sediments demonstrating that the stream bank serves as a deposition site for chemicals released to the channel. This finding has important implications on the long-term behavior of effluent contaminants since other studies at Los Alamos have shown that the vegetated stream banks retard downstream movement of chemicals bound to soils and provide a pathway for transport of these materials to biota. Concentrations of the radionuclides and mercury were more uniformly distributed with distance and depth in the channel sediments than in the bank soils. The action of periodic surface water in the channel partially explains those differences. Statistical analysis of the data revealed that 50 to 85% of the variability in contaminant concentrations in bank and channel locations was due to variation with distance while depth contributed relatively little to variability

  9. Understanding the effects of predictability, duration, and spatial pattern of drying on benthic invertebrate assemblages in two contrasting intermittent streams

    Science.gov (United States)

    von Schiller, Daniel; Barberá, Gonzalo G.; Díaz, Angela M.; Arce, Maria Isabel; del Campo, Rubén; Tockner, Klement

    2018-01-01

    In the present study, we examined the effects of different drying conditions on the composition, structure and function of benthic invertebrate assemblages. We approached this objective by comparing invertebrate assemblages in perennial and intermittent sites along two intermittent Mediterranean streams with contrasting predictability, duration, and spatial patterns of drying: Fuirosos (high predictability, short duration, downstream drying pattern) and Rogativa (low predictability, long duration, patchy drying pattern). Specifically, we quantified the contribution of individual taxa to those differences, the degree of nestedness, and shifts in the composition, structure and function of benthic invertebrate assemblages along flow intermittence gradients. We observed greater effects of drying on the benthic invertebrate composition in Fuirosos than in Rogativa, resulting in a higher dissimilarity of assemblages between perennial and intermittent sites, as well as a lower degree of nestedness. Furthermore, a higher number of biotic metrics related to richness, abundance and biological traits were significantly different between perennial and intermittent sites in Fuirosos, despite a shorter dry period compared to Rogativa. At the same time, slightly different responses were detected during post-drying (autumn) than pre-drying (spring) conditions in this stream. In Rogativa, shifts in benthic invertebrate assemblages along increasing gradients of flow intermittence were found for three metrics (Ephemeroptera, Plecoptera and Trichoptera (EPT) and Odonata, Coleoptera and Heteroptera (OCH) abundances and aerial active dispersal. Furthermore, we demonstrated that combined gradients of dry period duration and distance to nearest perennial reach can generate complex, and different, responses of benthic invertebrate assemblages, depending on the flow intermittence metric. Our study advances the notion that special attention should be paid to the predictability, duration and

  10. Use of ESI-FTICR-MS to Characterize Dissolved Organic Matter in Headwater Streams Draining Forest-Dominated and Pasture-Dominated Watersheds.

    Directory of Open Access Journals (Sweden)

    YueHan Lu

    Full Text Available Electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR-MS has proven to be a powerful technique revealing complexity and diversity of natural DOM molecules, but its application to DOM analysis in grazing-impacted agricultural systems remains scarce. In the present study, we presented a case study of using ESI-FTICR-MS in analyzing DOM from four headwater streams draining forest- or pasture-dominated watersheds in Virginia, USA. In all samples, most formulas were CHO compounds (71.8-87.9%, with other molecular series (CHOS, CHON, CHONS, and CHOP (N, S accounting for only minor fractions. All samples were dominated by molecules falling in the lignin-like region (H/C = 0.7-1.5, O/C = 0.1-0.67, suggesting the predominance of allochthonous, terrestrial plant-derived DOM. Relative to the two pasture streams, DOM formulas in the two forest streams were more similar, based on Jaccard similarity coefficients and nonmetric multidimensional scaling calculated from Bray-Curtis distance. Formulas from the pasture streams were characterized by lower proportions of aromatic formulas and lower unsaturation, suggesting that the allochthonous versus autochthonous contributions of organic matter to streams were modified by pasture land use. The number of condensed aromatic structures (CAS was higher for the forest streams, which is possibly due to the controlled burning in the forest-dominated watersheds and suggests that black carbon was mobilized from soils to streams. During 15-day biodegradation experiments, DOM from the two pasture streams was altered to a greater extent than DOM from the forest streams, with formulas with H/C and O/C ranges similar to protein (H/C = 1.5-2.2, O/C = 0.3-0.67, lipid (H/C = 1.5-2.0, O/C = 0-0.3, and unsaturated hydrocarbon (H/C = 0.7-1.5, O/C = 0-0.1 being the most bioreactive groups. Aromatic compound formulas including CAS were preferentially removed during combined light

  11. Combining multiple approaches and optimized data resolution for an improved understanding of stream temperature dynamics of a forested headwater basin in the Southern Appalachians

    Science.gov (United States)

    Belica, L.; Mitasova, H.; Caldwell, P.; McCarter, J. B.; Nelson, S. A. C.

    2017-12-01

    Thermal regimes of forested headwater streams continue to be an area of active research as climatic, hydrologic, and land cover changes can influence water temperature, a key aspect of aquatic ecosystems. Widespread monitoring of stream temperatures have provided an important data source, yielding insights on the temporal and spatial patterns and the underlying processes that influence stream temperature. However, small forested streams remain challenging to model due to the high spatial and temporal variability of stream temperatures and the climatic and hydrologic conditions that drive them. Technological advances and increased computational power continue to provide new tools and measurement methods and have allowed spatially explicit analyses of dynamic natural systems at greater temporal resolutions than previously possible. With the goal of understanding how current stream temperature patterns and processes may respond to changing landcover and hydroclimatoligical conditions, we combined high-resolution, spatially explicit geospatial modeling with deterministic heat flux modeling approaches using data sources that ranged from traditional hydrological and climatological measurements to emerging remote sensing techniques. Initial analyses of stream temperature monitoring data revealed that high temporal resolution (5 minutes) and measurement resolutions (guide field data collection for further heat flux modeling. By integrating multiple approaches and optimizing data resolution for the processes being investigated, small, but ecologically significant differences in stream thermal regimes were revealed. In this case, multi-approach research contributed to the identification of the dominant mechanisms driving stream temperature in the study area and advanced our understanding of the current thermal fluxes and how they may change as environmental conditions change in the future.

  12. [Relationship between leaf litter decomposition and colonization of benthic macroinvertebrates during early frost period in a headwater stream in the Changbai Mountains, Northeast China].

    Science.gov (United States)

    Wang, Lu; Yang, Hai Jun; Li, Ling; Nan, Xiao Fei; Zhang, Zhen Xing; Li, Kun

    2017-11-01

    Annually, about 70% of the streams in the Changbai Mountains are frosted during November to April, with manifest seasonal freeze-thaw characters. By using monoculture and mixing leaf litters of Tilia amurensis, Acer mono and Quecus mongolica, this research attempted to disentangle the relationship between leaf litter decomposition and colonization of macroinvertebrates in the stream during early frost period. A 35-day investigation was carried out in a headwater stream of the Changbai Mountains. Nylon bags with two hole sizes (5 mm and 0.3 mm) were used to examine decomposition of the litters. The results showed that the mass losses were significantly different among the three kinds of leaf litters in monoculture, whose decomposition rates descended as A. mono, T. amurensis, and Q. mongolica, however, there existed no significant difference among the litter mixing. Mass losses in both mesh bags all showed little difference, except T. amurensis and the mixed litters. Litter mixing effects occurred in the coarse mesh bags with A. mono and Q. mongolica, but no mixture effects for others. Community structures of the macroinvertebrates colonizing in the litter bags differed with each other, but shredders' density had no significant difference among the three litters, and the mixing effects on shredders were poor. Our results implied that microbes play the major decomposers of leaf litters, and macroinvertebrates contribute little to the decomposition in the early frost period. Despite shredder's density is lower, they determine the mixing effects of litters. Macroinvertebrates are selective to food and habitats, however, due to the short term colonizing, and the influence of leaf litters on shredders is still unsure. Our results might contribute to understanding the cold season ecological processes and related management issues of headwater stream ecosystem.

  13. Three-spined stickleback seasonal size and length-at-age distribution in an intermittent/perennial stream system

    Science.gov (United States)

    We examined the early life history of three-spined stickleback (Gasterosteus aculeatus) to better understand fish habitat patterns in an intermittent stream. We collected three-spined stickleback and other fishes using dipnets, seines and minnow traps during the summer 2010 low-...

  14. A detailed risk assessment of shale gas development on headwater streams in the Pennsylvania portion of the Upper Susquehanna River Basin, U.S.A.

    Science.gov (United States)

    Maloney, Kelly O.; Young, John A.; Faulkner, Stephen; Hailegiorgis, Atesmachew; Slonecker, E. Terrence; Milheim, Lesley

    2018-01-01

    The development of unconventional oil and gas (UOG) involves infrastructure development (well pads, roads and pipelines), well drilling and stimulation (hydraulic fracturing), and production; all of which have the potential to affect stream ecosystems. Here, we developed a fine-scaled (1:24,000) catchment-level disturbance intensity index (DII) that included 17 measures of UOG capturing all steps in the development process (infrastructure, water withdrawals, probabilistic spills) that could affect headwater streams (medium to high level DII scores (> 50). Well density, often used as a proxy for development, only correlated strongly with well pad coverage and produced materials, and therefore may miss potential effects associated with roads and pipelines, water withdrawals and spills. When analyzed with a future development scenario, 91.1% of EV stream length, 68.7% of Class A streams and 80.0% of patches were in catchments with a moderate to high probability of development. Our method incorporated the cumulative effects of UOG on streams and can be used to identify catchments and reaches at risk to existing stressors or future development.

  15. A groundwater salinity hotspot and its connection to an intermittent stream identified by environmental tracers (Mt Lofty Ranges, South Australia)

    Science.gov (United States)

    Anderson, Thomas A.; Bestland, Erick A.; Soloninka, Lesja; Wallis, Ilka; Banks, Edward W.; Pichler, Markus

    2017-12-01

    High and variable levels of salinity were investigated in an intermittent stream in a high-rainfall area (˜800 mm/year) of the Mt. Lofty Ranges of South Australia. The groundwater system was found to have a local, upslope saline lens, referred to here as a groundwater salinity `hotspot'. Environmental tracer analyses (δ18O, δ2H, 87/86Sr, and major elements) of water from the intermittent stream, a nearby permanent stream, shallow and deep groundwater, and soil-water/runoff demonstrate seasonal groundwater input of very saline composition into the intermittent stream. This input results in large salinity increases of the stream water because the winter wet-season stream flow decreases during spring in this Mediterranean climate. Furthermore, strontium and water isotope analyses demonstrate: (1) the upslope-saline-groundwater zone (hotspot) mixes with the dominant groundwater system, (2) the intermittent-stream water is a mixture of soil-water/runoff and the upslope saline groundwater, and (3) the upslope-saline-groundwater zone results from the flushing of unsaturated-zone salts from the thick clayey regolith and soil which overlie the metamorphosed shale bedrock. The preferred theory on the origin of the upslope-saline-groundwater hotspot is land clearing of native deep-rooted woodland, followed by flushing of accumulated salts from the unsaturated zone due to increased recharge. This cause of elevated groundwater and surface-water salinity, if correct, could be widespread in Mt. Lofty Ranges areas, as well as other climatically and geologically similar areas with comparable hydrogeologic conditions.

  16. Measurement of dissolved Cs-137 in stream water, soil water and groundwater at Headwater Forested Catchment in Fukushima after Fukushima Dai-ichi Nuclear Power Plant Accident

    Science.gov (United States)

    Iwagami, Sho; Tsujimura, Maki; Onda, Yuichi; Sakakibara, Koichi; Konuma, Ryohei; Sato, Yutaro

    2016-04-01

    Radiocesium migration from headwater forested catchment is important perception as output from the forest which is also input to the subsequent various land use and downstream rivers after Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident. In this study, dissolved Cs-137 concentration of stream water, soil water and groundwater were measured. Observations were conducted at headwater catchment in Yamakiya district, located 35 km northwest of FDNPP from April 2014 to November 2015. Stream water discharge was monitored and stream water samples were taken at main channel and sub channel. Stream water discharge was monitored by combination of parshallflume and v-notch weir. Stream water was sampled manually at steady state condition in 3-4 month interval and also intense few hours interval sampling were conducted during rainfall events using automated water sampler. Around the sub channel, it is found that there is a regularly saturated area at the bottom of the slope, temporary saturated area which saturate during the rainy season in summer and regularly dry area. 6 interval cameras were installed to monitor the changing situation of saturated area. Suction lysimeters were installed at three areas (regularly saturated area, temporary saturated area and dry area) for sampling soil water in depth of 0.1 m and 0.3 m. Boreholes were installed at three points along the sub channel. Three boreholes with depth of 3 m, 5 m and 10 m were installed at temporary saturated area, 20 m upstream of sub channel weir. Another three boreholes with depth of 3 m, 5 m and 10 m were installed at dry area, 40 m upstream of sub channel weir. And a borehole with depth of 20 m was installed at ridge of sub catchment, 52 m upstream of sub channel weir. Groundwater was sampled by electrically powered pump and groundwater level was monitored. Also suction-free lysimeter was installed at temporary saturated area for sampling the near surface subsurface water. Soil water samples were collected

  17. Effects of golf course construction and operation on water chemistry of headwater streams on the Precambrian Shield

    International Nuclear Information System (INIS)

    Winter, Jennifer G.; Dillon, Peter J.

    2005-01-01

    To investigate the effects of golf course construction and operation on the water chemistry of Shield streams, we compared the water chemistry in streams draining golf courses under construction (2) and in operation (5) to streams in forested reference locations and to upstream sites where available. Streams were more alkaline and higher in base cation and nitrate concentrations downstream of operational golf courses. Levels of these parameters and total phosphorus increased over time in several streams during golf course construction through to operation. There was evidence of inputs of mercury to streams on two of the operational courses. Nutrient (phosphorus and nitrogen) concentrations were significantly related to the area of unmanaged vegetation in a 30 x 30 m area on either side of the sampling sites, and to River Bank Quality Index scores, suggesting that maintaining vegetated buffers along the stream on golf courses will reduce in-stream nutrient concentrations. - Golf course construction and operation had a significant impact on alkalinity, nitrogen and base cation concentrations of streams

  18. Using the storm water management model to predict urban headwater stream hydrological response to climate and land cover change

    Science.gov (United States)

    J.Y. Wu; J.R. Thompson; R.K. Kolka; K.J. Franz; T.W. Stewart

    2013-01-01

    Streams are natural features in urban landscapes that can provide ecosystem services for urban residents. However, urban streams are under increasing pressure caused by multiple anthropogenic impacts, including increases in human population and associated impervious surface area, and accelerated climate change. The ability to anticipate these changes and better...

  19. The influence of environmental variables on the functional structure of headwater stream fish assemblages: a study of two tropical basins in Central Brazil

    Directory of Open Access Journals (Sweden)

    Rodrigo Assis Carvalho

    Full Text Available We investigated functional patterns of fish assemblages of two adjacent basins (Araguaia and Tocantins to test whether their headwater stream fish assemblages are more functionally (dissimilar than expected by chance and whether these (dissimilarities are related to differences of environmental conditions between basins. We used an analysis of similarities (ANOSIM on a functional dissimilarity matrix to test for (dissimilarities between fish assemblages of both basins. We performed RLQ and fourth-corner analyses to determine fish species trait-environment relationship. Our results revealed functional dissimilarities between fish assemblages of both basins and significant species trait-environment relationships, suggesting that environmental conditions are driving such dissimilarities. Inter-basin dissimilarities are mainly driven by altitudinal and water temperature gradients, whereas dissimilarities among streams within the basins are influenced by channel depth, turbidity and conductivity. These five environmental variables mostly affected six fish species traits (body mass, water column position, substrate preference, parental care, foraging locality and migration in different manners. This study is an attempt to understand functional trends of fish assemblages in a tropical region that remains poorly known but severely threatened.

  20. Stream Water, Carbon and Total Nitrogen Load Responses to a Simulated Emerald Ash Borer Infestation in Black Ash Dominated Headwater Wetlands

    Science.gov (United States)

    Van Grinsven, M. J.; Shannon, J.; Noh, N. J.; Kane, E. S.; Bolton, N. W.; Davis, J.; Wagenbrenner, J.; Sebestyen, S. D.; Kolka, R.; Pypker, T. G.

    2017-12-01

    The rapid and extensive expansion of emerald ash borer (EAB) is considered an important ecological and economic disturbance, and will likely affect critical ecosystem services associated with black ash wetlands. It is unknown how EAB-induced disturbance in wetlands dominated with black ash will impact stream water, dissolved organic carbon (DOC) and total dissolved nitrogen (TDN) export dynamics. We hypothesized that loads of water, DOC and TDN exported from black ash wetlands would be elevated following an EAB-induced disturbance. Stream water, DOC and TDN loads exiting two black ash wetlands in headwater watersheds in Michigan were quantified over a four-year period, and were combined with wetland soil temperature and soil decomposition rate monitoring to better understand the biogeochemical implications of an EAB-induced disturbance. After a two-year baseline monitoring period, an EAB disturbance was simulated by felling (ash-cut) all black ash trees with diameters greater than 2.5-cm in one wetland. When compared to the unaltered control, stream water DOC and TDN concentrations exiting the ash-cut wetland were significantly larger by 39% and 38%, respectively during the post-treatment study period. The significantly elevated DOC and TDN concentrations were likely associated with the higher soil temperatures and increased rates of soil decomposition detected in the ash-cut site during the post-treatment period. No significant mean daily stream discharge differences were detected between treatments during the pre-treatment period, however the 0.46 mm d-1 mean daily stream discharge exiting the ash-cut wetland was significantly smaller than the 1.07 mm d-1 exiting the unaltered control during the post-treatment study period. The significantly smaller daily stream discharge in the ash-cut site likely contributed to the fact no significant differences between treatments for either mean daily DOC loads or TDN loads were detected during the post-treatment period

  1. Heterogeneity in a Suburban River Network: Understanding the Impact of Fluvial Wetlands on Dissolved Oxygen and Metabolism in Headwater Streams

    Science.gov (United States)

    Cain, J. S.; Wollheim, W. M.; Sheehan, K.; Lightbody, A.

    2014-12-01

    Low dissolved oxygen content in rivers threatens fish populations, aquatic organisms, and the health of entire ecosystems. River systems with high fluvial wetland abundance and organic matter, may result in high metabolism that in conjunction with low re-aeration rates, lead to low oxygen conditions. Increasing abundance of beaver ponds in many areas may exacerbate this phenomenon. This research aims to understand the impact of fluvial wetlands, including beaver ponds, on dissolved oxygen (D.O.) and metabolism throughout the headwaters of the Ipswich R. watershed, MA, USA. In several fluvial wetland dominated systems, we measured diel D.O. and metabolism in the upstream inflow, the surface water transient storage zones of fluvial wetland sidepools, and at the outflow to understand how the wetlands modify dissolved oxygen. D.O. was also measured longitudinally along entire surface water flow paths (x-y km long) to determine how low levels of D.O. propagate downstream. Nutrient samples were also collected to understand how their behavior was related to D.O. behavior. Results show that D.O. in fluvial wetlands has large swings with periods of very low D.O. at night. D.O. swings were also seen in downstream outflow, though lagged and somewhat attenuated. Flow conditions affect the level of inundation and the subsequent effects of fluvial wetlands on main channel D.O.. Understanding the D.O. behavior throughout river systems has important implications for the ability of river systems to remove anthropogenic nitrogen.

  2. Land Use Influences Niche Size and the Assimilation of Resources by Benthic Macroinvertebrates in Tropical Headwater Streams.

    Directory of Open Access Journals (Sweden)

    Diego Marcel Parreira de Castro

    Full Text Available It is well recognized that assemblage structure of stream macroinvertebrates changes with alterations in catchment or local land use. Our objective was to understand how the trophic ecology of benthic macroinvertebrate assemblages responds to land use changes in tropical streams. We used the isotope methodology to assess how energy flow and trophic relations among macroinvertebrates were affected in environments affected by different land uses (natural cover, pasture, sugar cane plantation. Macroinvertebrates were sampled and categorized into functional feeding groups, and available trophic resources were sampled and evaluated for the isotopic composition of 13C and 15N along streams located in the Cerrado (neotropical savanna. Streams altered by pasture or sugar cane had wider and more overlapped trophic niches, which corresponded to more generalist feeding habits. In contrast, trophic groups in streams with native vegetation had narrower trophic niches with smaller overlaps, suggesting greater specialization. Pasture sites had greater ranges of resources exploited, indicating higher trophic diversity than sites with natural cover and sugar cane plantation. We conclude that agricultural land uses appears to alter the food base and shift macroinvertebrate assemblages towards more generalist feeding behaviors and greater overlap of the trophic niches.

  3. Flocculation of organic carbon from headwaters to estuary - the impact of soil erosion, water quality and land use on carbon transformation processes in eight streams draining Exmoor, UK

    Science.gov (United States)

    Snoalv, J.; Groeneveld, M.; Quine, T. A.; Tranvik, L.

    2017-12-01

    Flocculation of dissolved organic carbon (DOC) in streams and rivers is a process that contributes to the pool of particulate organic carbon (POC) in the aquatic system. In low-energy waters the increased sedimentation rates of this higher-density fraction of organic carbon (OC) makes POC important in allocating organic carbon into limnic storage, which subsequently influences emissions of greenhouse gases from the continental environment to the atmosphere. Allochthonous OC, derived from the terrestrial environment by soil erosion and litterfall, import both mineral aggregate-bound and free OC into freshwaters, which comprise carbon species of different quality and recalcitrance than autochthonous in-stream produced OC, such as from biofilms, aquatic plants and algae. Increased soil erosion due to land use change (e.g. agriculture, deforestation etc.) influences the input of allochthonous OC, which can lead to increased POC formation and sedimentation of terrestrial OC at flocculation boundaries in the landscape, i.e. where coagulation and flocculation processes are prone to occur in the water column. This study investigates the seasonal variation in POC content and flocculation capacity with respect to water quality (elemental composition) in eight river systems (four agricultural and four wooded streams) with headwaters in Exmoor, UK, that drain managed and non-managed land into Bristol Channel. Through flocculation experiments the samples were allowed to flocculate by treatments with added clay and salt standards that simulate the flocculation processes by 1) increased input of sediment into streams, and 2) saline mixing at the estuarine boundary, in order to quantify floc production and investigate POC quality by each process respectively. The results show how floc production, carbon quality and incorporation (e.g. complexation) of metals and rare earth elements (REE) in produced POC and remaining DOC in solution vary in water samples over the season and how

  4. LANDSCAPE INFLUENCES ON IN-STREAM BIOTIC INTEGRITY: USE OF MACROINVERTEBRATE METRICS TO IDENTIFY LANDSCAPE STRESSORS IN HEADWATER CATCHMENTS

    Science.gov (United States)

    The biotic integrity of streams is profoundly influenced by quantitative and qualitative features in the landscape of the surrounding catchment. In this study, aquatic macroinvertebrate metrics (e.g., relative abundance of Ephemeroptera, Trichoptera, and/or Plecoptera taxa, or t...

  5. Disturbance legacies of historic tie-drives persistently alter geomorphology and large wood characteristics in headwater streams, southeast Wyoming

    Science.gov (United States)

    Claire M. Ruffing; Melinda D. Daniels; Kathleen A. Dwire

    2015-01-01

    Instream wood is recognized as an integral component of stream morphology in forested areas. However, few studies have evaluated the legacy effects of historic wood removal activities and associated impacts on channel morphology, contemporary wood loading, and recruitment. This study investigates the role of historic tie-driving, a widespread channel disturbance legacy...

  6. Influence of large wood on channel morphology and sediment storage in headwater mountain streams, Fraser Experimental Forest, Colorado

    Science.gov (United States)

    Sandra E. Ryan; Erica L. Bishop; J. Michael Daniels

    2014-01-01

    Large fallen wood can have a significant impact on channel form and process in forested mountain streams. In this study, four small channels on the Fraser Experimental Forest near Fraser, Colorado, USA, were surveyed for channel geometries and large wood loading, including the size, source, and characteristics of individual pieces. The study is part of a larger effort...

  7. Storage and export of organic matter in a headwater stream: responses to long-term detrital manipulations

    Science.gov (United States)

    Sue L. Eggert; J. Bruce Wallace; Judy L. Meyer; Jackson R. Webster

    2012-01-01

    Riparian habitats provide organic matter inputs that influence stream biota and ecosystem processes in forested watersheds. Over a 13-yr period, we examined the effects of litter exclusion, small- and large-wood removal, and the addition of leaf species of varying detrital quality on organic matter standing crop and export of organic and inorganic particles in a high-...

  8. Nitrogen Dynamics Along a Headwater Stream Draining a Fen, Swamp, and Marsh in a Fractured Dolomite Watershed

    Science.gov (United States)

    Duval, T. P.; Waddington, J. M.

    2009-05-01

    Stream-wetland interaction has been shown to have a significant effect on nutrient cycling and downstream water quality. Additionally, connection to regional groundwater systems can dilute or enrich stream water with a number of dissolved constituents. This study demonstrates the resultant downstream change in dissolved nitrogen species as a hardwater stream emerges from a calcareous aquifer and traverses a calcareous fen, a cedar swamp, and a cattail marsh over two growing seasons, a very dry 2006 and a very wet 2007. Upon emergence at a number of groundwater seeps, the water contained appreciable nitrate levels averaging 2.72±0.42 mg NO3-N L-1, minimal organic nitrogen, and ammonium below detectable levels. Through the gently sloping calcareous fen, with a stream residence time of ~ 5 hours, NO3-N concentration decreases of 0.35 mg L-1 were observed. Concomitantly, stream recharge into the dolomite bedrock depressed stream discharge values significantly, further removing nitrate from the stream system. This resulted in the fen-bedrock system acting as an estimated net sink of 432 kg of NO3-N in the early summer of 2007, for example. In contrast, the hydrological-biogeochemical systems became decoupled through the swamp during the same period, where concentrations increased from 2.58±0.34 mg L-1 entering the swamp to 2.65±0.58 mg L-1 exiting, but streamflow decreased in general by 5 L s- 1. This resulted in the swamp, with its large depression storage, acting as a small net sink of nitrate (75 kg through the early summer), which would not be detected simply from concentration changes. The concentration-discharge relation realigned through the marsh, where significant groundwater entered the wetland, increasing both concentration and discharge, yielding a small export of 93 kg over the same time period. A series of tracer injections in each wetland type will be presented to compare the streamflow- concentration patterns with the measured nutrient spiralling

  9. Using microbiological tracers to assess the impact of winter land use restrictions on the quality of stream headwaters in a small catchment.

    Science.gov (United States)

    Flynn, Raymond M; Deakin, Jenny; Archbold, Marie; Cushnan, Hugh; Kilroy, Kate; O'Flaherty, Vincent; Misstear, Bruce D

    2016-01-15

    Diverse land use activities can elevate risk of microbiological contamination entering stream headwaters. Spatially distributed water quality monitoring carried out across a 17 km(2) agricultural catchment aimed to characterize microbiological contamination reaching surface water and investigate whether winter agricultural land use restrictions proved effective in addressing water quality degradation. Combined flow and concentration data revealed no significant difference in fecal indicator organism (FIO) fluxes in base flow samples collected during the open and prohibited periods for spreading organic fertilizer, while relative concentrations of Escherichia coli, fecal streptococci and sulfite reducing bacteria indicated consistently fresh fecal pollution reached aquatic receptors during both periods. Microbial source tracking, employing Bacteroides 16S rRNA gene markers, demonstrated a dominance of bovine fecal waste in river water samples upstream of a wastewater treatment plant discharge during open periods. This contrasted with responses during prohibited periods where human-derived signatures dominated. Differences in microbiological signature, when viewed with hydrological data, suggested that increasing groundwater levels restricted vertical infiltration of effluent from on-site wastewater treatment systems and diverted it to drains and surface water. Study results reflect seasonality of contaminant inputs, while suggesting winter land use restrictions can be effective in limiting impacts of agricultural wastes to base flow water quality. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. Fluvial wood function downstream of beaver versus man-made dams in headwater streams in Massachusetts, USA

    Science.gov (United States)

    David, G. C.; DeVito, L. F.; Munz, K. T.; Lisius, G.

    2014-12-01

    Fluvial wood is an essential component of stream ecosystems by providing habitat, increasing accumulation of organic matter, and increasing the processing of nutrients and other materials. However, years of channel alterations in Massachusetts have resulted in low wood loads despite the afforestation that has occurred since the early 1900s. Streams have also been impacted by a large density of dams, built during industrialization, and reduction of the beaver population. Beavers were reintroduced to Massachusetts in the 1940s and they have since migrated throughout the state. Beaver dams impound water, which traps sediment and results in the development of complex channel patterns and more ecologically productive and diverse habitats than those found adjacent to man-made dams. To develop better management practices for dam removal it is essential that we understand the geomorphic and ecologic function of wood in these channels and the interconnections with floodplain dynamics and stream water chemistry. We investigate the connections among fluvial wood, channel morphology, floodplain soil moisture dynamics, and stream water chemistry in six watersheds in Massachusetts that have been impacted by either beaver or man-made dams. We hypothesize that wood load will be significantly higher below beaver dams, subsequently altering channel morphology, water chemistry, and floodplain soil moisture. Reaches are surveyed up- and downstream of each type of dam to better understand the impact dams have on the fluvial system. Surveys include a longitudinal profile, paired with dissolved oxygen and ammonium measurements, cross-section and fluvial wood surveys, hydraulic measurements, and floodplain soil moisture mapping. We found that dissolved oxygen mirrored the channel morphology, but did not vary significantly between reaches. Wood loads were significantly larger downstream of beaver dams, which resulted in significant changes to the ammonium levels. Floodplain soil moisture

  11. [Characteristics of nitrogen and phosphorus retention in two different channel forms in a typical headwater stream in the suburb of Hefei City, China ].

    Science.gov (United States)

    Li, Ru-zhong; Yang, Ji-wei; Qian, Jing; Dong, Yu-hong; Tang, Wen-kun

    2014-09-01

    To investigate the characteristics of ammonium and phosphorus retention in two typical channel forms, deep pool and winding ditch in headwater stream, four field tracer experiments were conducted in a first-order stream of Ershibu River in Hefei suburban, in which a solution of biologically active (NH4Cl and KH2PO4) and conservative (NaCl) tracers was released to the head of each reach at a constant rate. According to the data sets of tracer experiments, mechanisms of ammonium and phosphorus retention were interpreted by using OTIS model code, transient storage metrics and nutrient spiraling theory. Study results showed that: (1) The value of As in deep pool was larger than that in winding ditch, whereas its value of hydrological parameter α was lower by an order of magnitude than that of winding ditch; (2) The value of NH(4)+ -λ in main channel was higher by two to three orders of magnitude than that of NH(4)+ -λs,in transient storage zone in deep pool, but in winding ditch the two parameters were closer in terms of numerical size; (3) In deep pool, the value of NH+(4) -Vf was higher by an order of magnitude than that of SRP-Vf, in winding ditch, however, not only the two values of NH(4)+ -Vf and SRP-Vf were close to each other, but NH(4)+ -Sw was nearly equal to SRP-Sw in numerical size as well; (4) The value of NH(4)+ -U was larger by two to three orders of magnitude than that of SRP-U in deep pool, whereas in winding ditch NH(4)+ -U was just larger by one to two orders of magnitude than SRP-U in size; (5) In general, significant difference existed between deep pool and winding ditch in the effect on ammonium and phosphorus retention, and marked retention efficiency was observed for ammonium rather than SRP in deep pool.

  12. A coupled geochemical and biogeochemical approach to characterize the bioreactivity of dissolved organic matter from a headwater stream

    Science.gov (United States)

    Sleighter, Rachel L.; Cory, Rose M.; Kaplan, Louis A.; Abdulla, Hussain A. N.; Hatcher, Patrick G.

    2014-08-01

    The bioreactivity or susceptibility of dissolved organic matter (DOM) to microbial degradation in streams and rivers is of critical importance to global change studies, but a comprehensive understanding of DOM bioreactivity has been elusive due, in part, to the stunningly diverse assemblages of organic molecules within DOM. We approach this problem by employing a range of techniques to characterize DOM as it flows through biofilm reactors: dissolved organic carbon (DOC) concentrations, excitation emission matrix spectroscopy (EEMs), and ultrahigh resolution mass spectrometry. The EEMs and mass spectral data were analyzed using a combination of multivariate statistical approaches. We found that 45% of stream water DOC was biodegraded by microorganisms, including 31-45% of the humic DOC. This bioreactive DOM separated into two different groups: (1) H/C centered at 1.5 with O/C 0.1-0.5 or (2) low H/C of 0.5-1.0 spanning O/C 0.2-0.7 that were positively correlated (Spearman ranking) with chromophoric and fluorescent DOM (CDOM and FDOM, respectively). DOM that was more recalcitrant and resistant to microbial degradation aligned tightly in the center of the van Krevelen space (H/C 1.0-1.5, O/C 0.25-0.6) and negatively correlated (Spearman ranking) with CDOM and FDOM. These findings were supported further by principal component analysis and 2-D correlation analysis of the relative magnitudes of the mass spectral peaks assigned to molecular formulas. This study demonstrates that our approach of processing stream water through bioreactors followed by EEMs and FTICR-MS analyses, in combination with multivariate statistical analysis, allows for precise, robust characterization of compound bioreactivity and associated molecular level composition.

  13. Identifying Controls on Patterns of Intermittent Streamflow in Three Streams of the American Southwest: A Geospatial Approach

    Science.gov (United States)

    Creed, C.; Kopp, D.; Allen, D. C.; Costigan, K. H.

    2017-12-01

    Intermittent rivers (IRs), or those waterways that cease to flow at some points in time and space along their course, are found in all parts of the world on all terrestrial landscapes and may even be more prevalent than their perennial, or continuously-flowing, counterparts. Despite a rising interest in these systems, landscape influences on long term wetting and drying patterns of streamflow are not well understood. Worldwide, there has been a significant decrease in the presence of perennial rivers due to climate change and subsequent increases in groundwater abstraction, and these effects are intensified in already arid regions such as the American Southwest. As a result, the spatial extent of wet and dry reaches of Arizona's Agua Fria River, Cienega Creek, and San Pedro River has been documented by citizen scientists during mid-June annually since 1999. Citizen science involves the use of trained members of the general public for data collection and analysis and has become a huge asset to the scientific community. Here, we synthesize the most current data (1999-2016) to determine what stream and valley characteristics act as drivers for patterns of surface water flow. Geologic, geomorphic, and land cover characteristics of these rivers were analyzed via aerial imagery and digital elevation models within ArcGIS 10.3 in conjunction with the Soil and Water Assessment Tool model. A set of intermittency metrics was produced from these data and further analyzed using Principle Component Analysis and Multiple Linear Regression. We found that land cover, specifically agriculture, had a significant positive correlation with reach average (i.e. the proportion of the channel wet), while geology and slope had a significant negative correlation. Channel characteristics (i.e. drainage and elevation) showed a positive correlation with reach average, although their results were not significant. This study begins to understand the drivers of intermittency patterns of desert

  14. Complex Effects of Free Stream Turbulence and Surface Roughness on the Transitional Intermittency

    Czech Academy of Sciences Publication Activity Database

    Hladík, Ondřej; Jonáš, Pavel; Mazur, Oton; Uruba, Václav

    2012-01-01

    Roč. 14, 4a (2012), s. 47-52 ISSN 1335-4205 R&D Projects: GA ČR GAP101/12/1271 Institutional research plan: CEZ:AV0Z20760514 Keywords : by-pass transition * rough wall boundary layer * CTA anemometry * instantaneous wall friction * intermittency analysis Subject RIV: BK - Fluid Dynamics

  15. Submersible UV-Vis spectroscopy for quantifying streamwater organic carbon dynamics: implementation and challenges before and after forest harvest in a headwater stream.

    Science.gov (United States)

    Jollymore, Ashlee; Johnson, Mark S; Hawthorne, Iain

    2012-01-01

    Organic material, including total and dissolved organic carbon (DOC), is ubiquitous within aquatic ecosystems, playing a variety of important and diverse biogeochemical and ecological roles. Determining how land-use changes affect DOC concentrations and bioavailability within aquatic ecosystems is an important means of evaluating the effects on ecological productivity and biogeochemical cycling. This paper presents a methodology case study looking at the deployment of a submersible UV-Vis absorbance spectrophotometer (UV-Vis spectro::lyzer model, s::can, Vienna, Austria) to determine stream organic carbon dynamics within a headwater catchment located near Campbell River (British Columbia, Canada). Field-based absorbance measurements of DOC were made before and after forest harvest, highlighting the advantages of high temporal resolution compared to traditional grab sampling and laboratory measurements. Details of remote deployment are described. High-frequency DOC data is explored by resampling the 30 min time series with a range of resampling time intervals (from daily to weekly time steps). DOC export was calculated for three months from the post-harvest data and resampled time series, showing that sampling frequency has a profound effect on total DOC export. DOC exports derived from weekly measurements were found to underestimate export by as much as 30% compared to DOC export calculated from high-frequency data. Additionally, the importance of the ability to remotely monitor the system through a recently deployed wireless connection is emphasized by examining causes of prior data losses, and how such losses may be prevented through the ability to react when environmental or power disturbances cause system interruption and data loss.

  16. Submersible UV-Vis Spectroscopy for Quantifying Streamwater Organic Carbon Dynamics: Implementation and Challenges before and after Forest Harvest in a Headwater Stream

    Directory of Open Access Journals (Sweden)

    Iain Hawthorne

    2012-03-01

    Full Text Available Organic material, including total and dissolved organic carbon (DOC, is ubiquitous within aquatic ecosystems, playing a variety of important and diverse biogeochemical and ecological roles. Determining how land-use changes affect DOC concentrations and bioavailability within aquatic ecosystems is an important means of evaluating the effects on ecological productivity and biogeochemical cycling. This paper presents a methodology case study looking at the deployment of a submersible UV-Vis absorbance spectrophotometer (UV-Vis spectro::lyzer model, s::can, Vienna, Austria to determine stream organic carbon dynamics within a headwater catchment located near Campbell River (British Columbia, Canada. Field-based absorbance measurements of DOC were made before and after forest harvest, highlighting the advantages of high temporal resolution compared to traditional grab sampling and laboratory measurements. Details of remote deployment are described. High-frequency DOC data is explored by resampling the 30 min time series with a range of resampling time intervals (from daily to weekly time steps. DOC export was calculated for three months from the post-harvest data and resampled time series, showing that sampling frequency has a profound effect on total DOC export. DOC exports derived from weekly measurements were found to underestimate export by as much as 30% compared to DOC export calculated from high-frequency data. Additionally, the importance of the ability to remotely monitor the system through a recently deployed wireless connection is emphasized by examining causes of prior data losses, and how such losses may be prevented through the ability to react when environmental or power disturbances cause system interruption and data loss.

  17. Characterization of major-ion chemistry and nutrients in headwater streams along the Appalachian National Scenic Trail and within adjacent watersheds, Maine to Georgia

    Science.gov (United States)

    Argue, Denise M.; Pope, Jason P.; Dieffenbach, Fred

    2012-01-01

    An inventory of water-quality data on field parameters, major ions, and nutrients provided a summary of water quality in headwater (first- and second-order) streams within watersheds along the Appalachian National Scenic Trail (Appalachian Trail). Data from 1,817 sampling sites in 831 catchments were used for the water-quality summary. Catchment delineations from NHDPlus were used as the fundamental geographic units for this project. Criteria used to evaluate sampling sites for inclusion were based on selected physical attributes of the catchments adjacent to the Appalachian Trail, including stream elevation, percentage of developed land cover, and percentage of agricultural land cover. The headwater streams of the Appalachian Trail are generally dilute waters, with low pH, low acid neutralizing capacity (ANC), and low concentrations of nutrients. The median pH value was slightly acidic at 6.7; the median specific conductance value was 23.6 microsiemens per centimeter, and the median ANC value was 98.7 milliequivalents per liter (μeq/L). Median concentrations of cations (calcium, magnesium, sodium, and potassium) were each less than 1.5 milligrams per liter (mg/L), and median concentrations of anions (bicarbonate, chloride, fluoride, sulfate, and nitrate) were less than 10 mg/L. Differences in water-quality constituent levels along the Appalachian Trail may be related to elevation, atmospheric deposition, geology, and land cover. Spatial variations were summarized by ecological sections (ecosections) developed by the U.S. Forest Service. Specific conductance, pH, ANC, and concentrations of major ions (calcium, chloride, magnesium, sodium, and sulfate) were all negatively correlated with elevation. The highest elevation ecosections (White Mountains, Blue Ridge Mountains, and Allegheny Mountains) had the lowest pH, ANC, and concentrations of major ions. The lowest elevation ecosections (Lower New England and Hudson Valley) generally had the highest pH, ANC, and

  18. Biomonitoring of intermittent rivers and ephemeral streams in Europe: Current practice and priorities to enhance ecological status assessments.

    Science.gov (United States)

    Stubbington, Rachel; Chadd, Richard; Cid, Núria; Csabai, Zoltán; Miliša, Marko; Morais, Manuela; Munné, Antoni; Pařil, Petr; Pešić, Vladimir; Tziortzis, Iakovos; Verdonschot, Ralf C M; Datry, Thibault

    2018-03-15

    Intermittent rivers and ephemeral streams (IRES) are common across Europe and dominate some Mediterranean river networks. In all climate zones, IRES support high biodiversity and provide ecosystem services. As dynamic ecosystems that transition between flowing, pool, and dry states, IRES are typically poorly represented in biomonitoring programmes implemented to characterize EU Water Framework Directive ecological status. We report the results of a survey completed by representatives from 20 European countries to identify current challenges to IRES status assessment, examples of best practice, and priorities for future research. We identify five major barriers to effective ecological status classification in IRES: 1. the exclusion of IRES from Water Framework Directive biomonitoring based on their small catchment size; 2. the lack of river typologies that distinguish between contrasting IRES; 3. difficulties in defining the 'reference conditions' that represent unimpacted dynamic ecosystems; 4. classification of IRES ecological status based on lotic communities sampled using methods developed for perennial rivers; and 5. a reliance on taxonomic characterization of local communities. Despite these challenges, we recognize examples of innovative practice that can inform modification of current biomonitoring activity to promote effective IRES status classification. Priorities for future research include reconceptualization of the reference condition approach to accommodate spatiotemporal fluctuations in community composition, and modification of indices of ecosystem health to recognize both taxon-specific sensitivities to intermittence and dispersal abilities, within a landscape context. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

  19. Watershed to Local Scale Characteristics and Function of Intermittent and Ephemeral Streams on Military Lands

    Science.gov (United States)

    2015-07-31

    stream types in riparian plant community composition ( PerMANOVA ) and compositional variance (PermDISP...111 Table 5-3. Pairwise comparisons for differences in riparian plant community composition ( PerMANOVA ) among...multidimensional scaling ordination PerManova = permutational multivariate analysis of variance PC-Ord = computer program for multivariate statistics

  20. Comparison of groundwater recharge estimation techniques in an alluvial aquifer system with an intermittent/ephemeral stream (Queensland, Australia)

    Science.gov (United States)

    King, Adam C.; Raiber, Matthias; Cox, Malcolm E.; Cendón, Dioni I.

    2017-09-01

    This study demonstrates the importance of the conceptual hydrogeological model for the estimation of groundwater recharge rates in an alluvial system interconnected with an ephemeral or intermittent stream in south-east Queensland, Australia. The losing/gaining condition of these streams is typically subject to temporal and spatial variability, and knowledge of these hydrological processes is critical for the interpretation of recharge estimates. Recharge rate estimates of 76-182 mm/year were determined using the water budget method. The water budget method provides useful broad approximations of recharge and discharge fluxes. The chloride mass balance (CMB) method and the tritium method were used on 17 and 13 sites respectively, yielding recharge rates of 1-43 mm/year (CMB) and 4-553 mm/year (tritium method). However, the conceptual hydrogeological model confirms that the results from the CMB method at some sites are not applicable in this setting because of overland flow and channel leakage. The tritium method was appropriate here and could be applied to other alluvial systems, provided that channel leakage and diffuse infiltration of rainfall can be accurately estimated. The water-table fluctuation (WTF) method was also applied to data from 16 bores; recharge estimates ranged from 0 to 721 mm/year. The WTF method was not suitable where bank storage processes occurred.

  1. Collaborative Approaches to Flow Restoration in Intermittent Salmon-Bearing Streams: Salmon Creek, CA, USA

    Directory of Open Access Journals (Sweden)

    Cleo Woelfle-Erskine

    2017-03-01

    Full Text Available In Mediterranean-climate regions of California and southern Oregon, juvenile salmon depend on groundwater aquifers to sustain their tributary habitats through the dry summers. Along California’s North Coast streams, private property regimes on land have created commons tragedies in groundwater and salmon fisheries, both classic examples of commons that are often governed collectively and sustainably by their users. Understanding the linkages between salmon and groundwater is one major focus of salmon recovery and climate change adaptation planning in central California and increasingly throughout the Pacific Northwest. In this paper, I use extended field interviews and participant-observation in field ecology campaigns and regulatory forums to explore how, in one water-scarce, salmon-bearing watershed on California’s central coast, collaborators are synthesizing agency and landowner data on groundwater and salmon management. I focus on three projects undertaken by citizen scientists in collaboration with me and Gold Ridge Resource Conservation District staff: salmonid censuses, mapping of wet and dry stream reaches and well monitoring. I find that collaborative research initiated by local residents and agency personnel has, in some cases, created a new sense of ecological possibility in the region. I also consider some limitations of this collaborations, namely the lack of engagement with indigenous Pomo and Miwok tribal members, with the Confederated Tribes of Graton Rancheria and with farmworkers and other marginalized residents, and suggest strategies for deepening environmental justice commitments in future collaborative work.

  2. Variability of streambed hydraulic conductivity in an intermittent stream reach regulated by Vented Dams: A case study

    Science.gov (United States)

    Naganna, Sujay Raghavendra; Deka, Paresh Chandra

    2018-07-01

    The hydro-geological properties of streambed together with the hydraulic gradients determine the fluxes of water, energy and solutes between the stream and underlying aquifer system. Dam induced sedimentation affects hyporheic processes and alters substrate pore space geometries in the course of progressive stabilization of the sediment layers. Uncertainty in stream-aquifer interactions arises from the inherent complex-nested flow paths and spatio-temporal variability of streambed hydraulic properties. A detailed field investigation of streambed hydraulic conductivity (Ks) using Guelph Permeameter was carried out in an intermittent stream reach of the Pavanje river basin located in the mountainous, forested tract of western ghats of India. The present study reports the spatial and temporal variability of streambed hydraulic conductivity along the stream reach obstructed by two Vented Dams in sequence. Statistical tests such as Levene's and Welch's t-tests were employed to check for various variability measures. The strength of spatial dependence and the presence of spatial autocorrelation among the streambed Ks samples were tested by using Moran's I statistic. The measures of central tendency and dispersion pointed out reasonable spatial variability in Ks distribution throughout the study reach during two consecutive years 2016 and 2017. The streambed was heterogeneous with regard to hydraulic conductivity distribution with high-Ks zones near the backwater areas of the vented dam and low-Ks zones particularly at the tail water section of vented dams. Dam operational strategies were responsible for seasonal fluctuations in sedimentation and modifications to streambed substrate characteristics (such as porosity, grain size, packing etc.), resulting in heterogeneous streambed Ks profiles. The channel downstream of vented dams contained significantly more cohesive deposits of fine sediment due to the overflow of surplus suspended sediment-laden water at low velocity

  3. A synoptic survey of ecosystem services from headwater catchments in the United States

    Science.gov (United States)

    Brian H. Hill; Randall K. Kolka; Frank H. McCormick; Matthew A. Starry

    2014-01-01

    Ecosystem production functions for water supply, climate regulation, and water purification were estimated for 568 headwater streams and their catchments. Results are reported for nine USA ecoregions. Headwater streams represented 74-80% of total catchment stream length. Water supply per unit catchment area was highest in the Northern Appalachian Mountains ecoregion...

  4. Assessing changes to in-stream turbidity following construction of a forest road in West Virginia

    Science.gov (United States)

    Jingxin Wang; Pamela J. Edwards; William A. Goff

    2011-01-01

    Two forested headwater watersheds were monitored to examine changes to in-stream turbidity following the construction of a forest haul road. One watershed was used as an undisturbed reference, while the other had a 0.92-km (0.57-mi) haul road constructed in it. The channels in both are intermittent tributaries of the Left Fork of Clover Run in the Cheat River watershed...

  5. Ecologia da ictiofauna de um córrego de cabeceira da bacia do alto rio Paraná, Brasil Ecology of the ichthyofauna of a headwater stream of the upper Paraná River basin, Brazil

    Directory of Open Access Journals (Sweden)

    Elis Mara Lemes

    2002-09-01

    Full Text Available Ecological studies were conducted in the ichthyofauna of Cedro, a small headwater stream located in a degraded area of State of São Paulo, Brazil, situated in the upper Paraná River basin. These are the results of two non-consecutive years observations and collections in two biotopes of that stream: a pool and a rapid. The ecological characteristics studied change in space and time. The present richness of species is high (21 species, nine of which are constant, six accessory and six accidental. The diversity is low (0.69 to 2.38, and the numeric predominance, from one to three species, occurred in both biotopes. The most frequent species are Poecilia reticulata (Peters, 1859 (28.1%, Corydoras cf. aeneus (Gill, 1858 (20.3% and Hypostomus cf. ancistroides (Ihering, 1911 (19.8%. The density ranges from 0.7 to 19.8 specimens/m³. The similarity index indicates high similarity between the ichthyofauna (45.0% to 95.0% inside the same or contiguous biotopes. The evenness (0.46 to 1.0 is comparable to those found in similar studies carried out in other streams.

  6. Validating the Operational Draft Regional Guidebook for the Functional Assessment of High-Gradient Ephemeral and Intermittent Headwater Streams in Western West Virginia and Eastern Kentucky

    Science.gov (United States)

    2014-04-01

    blackgum, wild black cherry (Prunus serotina), sweet cherry (Prunus avium), slippery elm (Ulmus rubra), sourwood (Oxydendrum arboreum), red maple, and...virginiana), American hornbeam (Carpinus caroliniana), and slippery elm . Buffalo nut (Pyrularia pubera), wild hydrangea (Hydrangea arborescens...Pinus strobus), wild black cherry, boxelder (Acer negundo), sycamore, black locust (Robinia pseudo-acacia), slippery elm , and white ash. The shrub

  7. Streamside policies for headwater channels: an example considering debris flows in the Oregon coastal province.

    Science.gov (United States)

    K.M. Burnett; D.J. Miller

    2007-01-01

    Headwater streams differ in susceptibility to debris flows and thus in importance as wood and sediment sources for larger rivers. Identifying and appropriately managing the most susceptible headwater streams is of interest. We developed and illustrated a method to delineate alternative aquatic conservation emphasis zones (ACEZs) considering probabilities for traversal...

  8. Variations in surface water-ground water interactions along a headwater mountain stream: comparisons between transient storage and water balance analyses

    Science.gov (United States)

    Adam S. Ward; Robert A. Payn; Michael N. Gooseff; Brian L. McGlynn; Kenneth E. Bencala; Christa A. Kellecher; Steven M. Wondzell; Thorsten. Wagener

    2013-01-01

    The accumulation of discharge along a stream valley is frequently assumed to be the primary control on solute transport processes. Relationships of both increasing and decreasing transient storage, and decreased gross losses of stream water have been reported with increasing discharge; however, we have yet to validate these relationships with extensive field study. We...

  9. Influence of eastern hemlock (Tsuga canadensis L.) on fish community structure and function in headwater streams of the Delaware River basin

    Science.gov (United States)

    Ross, R.M.; Bennett, R.M.; Snyder, C.D.; Young, J.A.; Smith, D.R.; Lemarie, D.P.

    2003-01-01

    Hemlock (Tsuga canadensis) forest of the eastern U.S. are in decline due to invasion by the exotic insect hemlock woolly adelgid (Adelges tsugae). Aquatic biodiversity in hemlock ecosystems has not been documented; thus the true impact of the infestation cannot be assessed. We compared ichthyofaunal assemblages and trophic structure of streams draining hemlock and hardwood forests by sampling first- and second-order streams draining 14 paired hemlock and hardwood stands during base flows in July 1997 at the Delaware Water Gap National Recreation Area of Pennsylvania and New Jersey. Over 1400 fish of 15 species and 7 families were collected, but hemlock and hardwood streams individually harbored only one to four species. Brook trout (Salvelinus fontinalis) and brown trout (Salmo trutta) were two to three times as prevalent in hemlock than hardwood streams. Insectivorous fishes occurred in significantly higher proportion in streams of hardwood (0.90) than hemlock (0.46) stands, while piscivores occurred more often in hemlock (0.85) than hardwood (0.54) stands. Functional (trophic) diversity of fishes in hemlock and second-order streams was numerically greater than that of hardwood and first-order streams. Species composition also differed by stream order and terrain type. Biodiversity is threatened at several levels within hemlock ecosystems at risk to the hemlock woolly adelgid in eastern U.S. forests.

  10. Non-indigenous bamboo along headwater streams of the Luquillo Mountains, Puerto Rico: leaf fall, aquatic leaf decay and patterns of invasion

    Science.gov (United States)

    PAUL J. O' CONNOR; ALAN P. COVICH; F. N. SCATENA; LLOYD L. LOOPE

    2000-01-01

    The introduction of bamboo to montane rain forests of the Luquillo Mountains, Puerto Rico in the 1930s and 1940s has led to present-day bamboo monocultures in numerous riparian areas. When a non-native species invades a riparian ecosystem, in-stream detritivores can be affected. Bamboo dynamics expected to in¯uence stream communities in the Luquillo Experimental Forest...

  11. Future ecological studies of Brazilian headwater streams under global-changes Estudos ecológicos futuros em riachos de cabeceira na perspectiva de mudanças globais

    Directory of Open Access Journals (Sweden)

    Marcos Callisto

    2012-09-01

    Full Text Available This paper results from discussions triggered during the "Stream Ecology Symposium" that took place at the XIII Congress of the Brazilian Society of Limnology in September of 2011 in Natal, Brazil. Based on our experiences, we have raised several questions regarding ecological studies of headwater streams facing threats under global-changes and proposed numerous subjects to be addressed in future studies in Brazil. These studies deal with the necessity of knowing species biology and the elaboration of models to assess changes (which implies the availability of time-series or large-scale data sets; the ecology of riparian zones and the interchange of materials and energy across the land-water boundaries; forest conversions and standardized sampling strategies and data treatment to assess global change.Este artigo resulta de discussões ocorridas durante o Simpósio de Ecologia de Riachos que aconteceu durante o XIII Congresso da Sociedade Brasileira de Limnologia em setembro de 2011 em Natal, Brasil. Baseados em nossa experiência, propomos algumas perguntas sobre ecologia de riachos na perspectiva de mudanças globais e sugerimos alguns aspectos a serem abordados em futuros estudos no país. Esses estudos estão relacionados à necessidade de se conhecer a biologia das espécies; à elaboração de modelos para avaliar as mudanças (o que implica a necessidade de um grande volume de dados em larga escala temporal e espacial; a ecologia das zonas ribeirinhas e o intercâmbio de materiais e energia através das interfaces terra-água; as alterações na cobertura florestal e estratégias de amostragem e tratamento de dados padronizados para avaliar as mudanças globais.

  12. Using fluorescence spectroscopy to gain new insights into seasonal patterns of stream DOC concentrations in an alpine, headwater catchment underlain by discontinuous permafrost in Wolf Creek Research Basin, Yukon Territory, Canada

    Science.gov (United States)

    Shatilla, N. J.; Carey, S.; Tang, W.

    2017-12-01

    The Canadian subarctic is experiencing rapid climate warming resulting in decreased depth and duration of snowcover, decreased permafrost extent and time span of seasonal frozen ground resulting in increased active layer depth, and increased frequency and magnitude of rainfall events during the growing season. These changes challenge our conceptual models of permafrost hydrology as comparisons between recent and historical streamflow records show an emerging secondary post-freshet peak in flow in recent years along with enhanced winter flows. Long-term monitoring of Granger Creek (7.6km2), an alpine watershed underlain by discontinuous permafrost located within Wolf Creek Research Basin (176km2) in Yukon Territory, Canada provided a multi-decadal record of hydro-meteorological measurements. Granger Creek experienced warmer and wetter summers in 2015-6 compared to 2001-8, and an altered streamflow pattern with an earlier spring freshet and peak in dissolved organic carbon (DOC) concentrations. DOC concentrations post-freshet remained low at both the headwater and meso-catchment scale, which contradicts trends of increasing DOC concentrations observed in larger river systems. Hysteresis loops of sub-hourly measurements of streamflow, salinity and chromophoric dissolved organic matter (CDOM) were analyzed to provide new insights into how hydrological connectivity at the headwater scale affected the timing of solute release with supporting information from optical indices calculated from fluorescence spectroscopy. These indices provided a more nuanced view of catchment dynamics than the DOC concentrations. The composition and quality of DOM varied throughout the growing season with the delivery of older, terrestrially-derived material corresponding to high DOC concentrations at the onset of spring freshet when the catchment was initially being flushed. The origin and quality of stream DOM shifted throughout the rest of the season to newer, more easily mobilized DOM

  13. Distribution of aquatic insects in urban headwater streams Distribuição de insetos aquáticos em riachos urbanos

    Directory of Open Access Journals (Sweden)

    Luiz Ubiratan Hepp

    2013-01-01

    Full Text Available AIMS: The objective of this study was to evaluate the effects of urban environments on the distribution and occurrence of aquatic Ephemeroptera, Plecoptera and Trichoptera (EPT insects in six urban subtropical streams; METHODS: Organisms were collected with a Surber sampler in 2005 and 2006, over two hydrological cycles. We analyzed abundance values, taxonomic richness, Shannon-Wiener diversity and Pielou's evenness. A principal components analysis (PCA was performed to evaluate the environmental variability of streams. A canonical correspondence analysis (CCA was performed to evaluate the possible effects of environmental variables; RESULTS: The PCA ordered the streams according to their quality, and Suzana and Nadau streams had higher concentrations of nutrients. The Baetidae (Ephemeroptera was the family with the highest number of genera (18. Perissophlebiodes Savage, 1983, and Americabaetis Kluge, 1992, were the most common genera. Anacroneuria Klapálek, 1909, was the most abundant Pleocoptera, and Smicridea McLachlan, 1871, was the dominant Trichoptera genus. In the CCA, pH, electrical conductivity and stream velocity were positively correlated with axis 1, whereas dissolved oxygen was negatively correlated with axis 1; CONCLUSIONS: Our results show that the distribution of EPT in urban streams is affected by changes in water physicochemical characteristics. However, these changes are not sufficiently severe to cause the elimination of EPT.OBJETIVOS: O objetivo deste estudo foi avaliar os efeitos da urbanização sobre a ocorrência e distribuição de insetos aquáticos das ordens Ephemeroptera, Plecoptera e Trichoptera (EPT em seis riachos subtropicais; MÉTODOS: Os organismos foram coletados com um amostrador Surber, durante os anos 2005 e 2006, abrangendo dois ciclos hidrológicos. Foram analisados os valores de abundância, riqueza taxonômica, diversidade Shannon-Wiener e equitabilidade de Pielou. Uma Análise de Componentes

  14. Assessing the consequences of nonnative trout in headwater ecosystems in western North America

    Science.gov (United States)

    Jason B. Dunham; David S. Pilliod; Michael K. Young

    2004-01-01

    Intentional introductions of nonnative trout into headwater lakes and streams can have numerous effects on the receiving ecosystems, potentially threatening native species and disrupting key ecological processes. In this perspective, we focus on seven key issues for assessing the biological and economic consequences of nonnative trout in headwater ecosystems: (1)...

  15. A Hydrogeochemical Study of the Evolution of the Headwaters of the Bear River in the Uinta Mountains, Utah

    OpenAIRE

    Leschin, Michael F.

    1997-01-01

    The headwaters of the Bear River in the Uinta Mountains of Utah provide a good setting in which to examine the influence of geological materials on stream chemistry. Ionic contributions to the stream-water from soils, vegetation, and the atmosphere generally are sparse enough that they do not mask the geologic contributions. Samples from 37 sites on the four major headwater streams and several minor tributaries were examined geochemically. Data derived from the samples allowed the constructio...

  16. Energy intermittency

    CERN Document Server

    Sorensen, Bent

    2014-01-01

    The first book to consider intermittency as a key point of an energy system, Energy Intermittency describes different levels of variability for traditional and renewable energy sources, presenting detailed solutions for handling energy intermittency through trade, collaboration, demand management, and active energy storage. Addressing energy supply intermittency systematically, this practical text:Analyzes typical time-distributions and intervals between episodes of demand-supply mismatch and explores their dependence on system layouts and energy source characteristicsSimulates scenarios regar

  17. STREAM

    DEFF Research Database (Denmark)

    Godsk, Mikkel

    This paper presents a flexible model, ‘STREAM’, for transforming higher science education into blended and online learning. The model is inspired by ideas of active and collaborative learning and builds on feedback strategies well-known from Just-in-Time Teaching, Flipped Classroom, and Peer...... Instruction. The aim of the model is to provide both a concrete and comprehensible design toolkit for adopting and implementing educational technologies in higher science teaching practice and at the same time comply with diverse ambitions. As opposed to the above-mentioned feedback strategies, the STREAM...... model supports a relatively diverse use of educational technologies and may also be used to transform teaching into completely online learning. So far both teachers and educational developers have positively received the model and the initial design experiences show promise....

  18. The significance of small streams

    Science.gov (United States)

    Wohl, Ellen

    2017-09-01

    Headwaters, defined here as first- and secondorder streams, make up 70%‒80% of the total channel length of river networks. These small streams exert a critical influence on downstream portions of the river network by: retaining or transmitting sediment and nutrients; providing habitat and refuge for diverse aquatic and riparian organisms; creating migration corridors; and governing connectivity at the watershed-scale. The upstream-most extent of the channel network and the longitudinal continuity and lateral extent of headwaters can be difficult to delineate, however, and people are less likely to recognize the importance of headwaters relative to other portions of a river network. Consequently, headwaters commonly lack the legal protections accorded to other portions of a river network and are more likely to be significantly altered or completely obliterated by land use.

  19. C, N, P export regimes from headwater catchments to downstream reaches

    Science.gov (United States)

    Dupas, R.; Musolff, A.; Jawitz, J. W.; Rao, P. S.; Jaeger, C. G.; Fleckenstein, J. H.; Rode, M.; Borchardt, D.

    2017-12-01

    Excessive amounts of nutrients and dissolved organic matter in freshwater bodies affect aquatic ecosystems. In this study, the spatial and temporal variability in nitrate (NO3), dissolved organic carbon (DOC) and soluble reactive phosphorus (SRP) was analyzed in the Selke river continuum from headwaters draining 1 - 3 km² catchments to downstream reaches representing spatially integrated signals from 184 - 456 km² catchments (part of TERENO - Terrestrial Environmental Observatories, in Germany). Three headwater catchments were selected as archetypes of the main landscape units (land use x lithology) present in the Selke catchment. Export regimes in headwater catchments were interpreted in terms of NO3, DOC and SRP land-to-stream transfer processes. Headwater signals were subtracted from downstream signals, with the differences interpreted in terms of in-stream processes and contribution of point-source emissions. The seasonal dynamics for NO3 were opposite those of DOC and SRP in all three headwater catchments, and spatial differences also showed NO3 contrasting with DOC and SRP. These dynamics were interpreted as the result of the interplay of hydrological and biogeochemical processes, for which riparian zones were hypothesized to play a determining role. In the two downstream reaches, NO3 was transported almost conservatively, whereas DOC was consumed and produced in the upper and lower river sections, respectively. The natural export regime of SRP in the three headwater catchments mimicked a point-source signal, which may lead to overestimation of domestic contributions in the downstream reaches. Monitoring the river continuum from headwaters to downstream reaches proved effective to investigate jointly land-to-stream and in-stream transport and transformation processes.

  20. The success of headwater rehabilitation towards gully erosion control

    Science.gov (United States)

    Frankl, Amaury; Poesen, Jean; Nyssen, Jan

    2017-04-01

    The ill-management of headwaters has frequently shown to have adverse effects on both humans and the environment. Historical examples often refer to altered hydrological conditions and stream incision resulting from deforestation. Agricultural expansion and intensification - often accompanied with land reforms in the 20th century - also showed to severely impact the fluvial environment, with stream incision and gully erosion hazards increasingly affecting many headwater areas around the world. To counter this, many regions have adopted improved management schemes aiming at restoring the physical, biological and hydrological integrity of the soil- and landscape. In terms of hydrogeomorpology, the objective was to minimize dynamics to a lower level so that runoff, sediment and pollutant transfers do not cause danger to human life, environmental/natural resources deterioration or economic stress. Therefore, much attention was given to the rehabilitation and re-naturalization of headwater streams and gullies, which are the conduits of these transfers. This is done in both indirect and direct ways, i.e. reducing the delivery of runoff and sediment to the gullies and interventions in the incised channels. Although much has been published on gully erosion development and control, few studies assess the success of gully rehabilitation on the mid- to long term or confront results against the gully life-cycle. The latter refers to the rate law in fluvial geomorphology, whereby gully morphological changes (increases in length, area, volume) are initially rapid, followed by a much slower development towards a new equilibrium state. Here, we present a review of headwater rehabilitation measures and their success towards gully erosion control. By confronting this to the life-cycle of a gully, we also want to shed light on our understanding of when and where gully erosion control needs to be applied; making land management more efficient and effective. Keywords: land

  1. Estimating retention potential of headwater catchment using Tritium time series

    Science.gov (United States)

    Hofmann, Harald; Cartwright, Ian; Morgenstern, Uwe

    2018-06-01

    Headwater catchments provide substantial streamflow to rivers even during long periods of drought. Documenting the mean transit times (MTT) of stream water in headwater catchments and therefore the retention capacities of these catchments is crucial for water management. This study uses time series of 3H activities in combination with major ion concentrations, stable isotope ratios and radon activities (222Rn) in the Lyrebird Creek catchment in Victoria, Australia to provide a unique insight into the mean transit time distributions and flow systems of this small temperate headwater catchment. At all streamflows, the stream has 3H activities (water in the stream is derived from stores with long transit times. If the water in the catchment can be represented by a single store with a continuum of ages, mean transit times of the stream water range from ∼6 up to 40 years, which indicates the large retention potential for this catchment. Alternatively, variations of 3H activities, stable isotopes and major ions can be explained by mixing between of young recent recharge and older water stored in the catchment. While surface runoff is negligible, the variation in stable isotope ratios, major ion concentrations and radon activities during most of the year is minimal (±12%) and only occurs during major storm events. This suggests that different subsurface water stores are activated during the storm events and that these cease to provide water to the stream within a few days or weeks after storm events. The stores comprise micro and macropore flow in the soils and saprolite as well as the boundary between the saprolite and the fractured bed rock. Hydrograph separations from three major storm events using Tritium, electrical conductivity and selected major ions as well a δ18O suggest a minimum of 50% baseflow at most flow conditions. We demonstrate that headwater catchments can have a significant storage capacity and that the relationship between long-water stores and

  2. Shallow bedrock limits groundwater seepage-based headwater climate refugia

    Science.gov (United States)

    Briggs, Martin A.; Lane, John W.; Snyder, Craig D.; White, Eric A.; Johnson, Zachary; Nelms, David L.; Hitt, Nathaniel P.

    2018-01-01

    Groundwater/surface-water exchanges in streams are inexorably linked to adjacent aquifer dynamics. As surface-water temperatures continue to increase with climate warming, refugia created by groundwater connectivity is expected to enable cold water fish species to survive. The shallow alluvial aquifers that source groundwater seepage to headwater streams, however, may also be sensitive to seasonal and long-term air temperature dynamics. Depth to bedrock can directly influence shallow aquifer flow and thermal sensitivity, but is typically ill-defined along the stream corridor in steep mountain catchments. We employ rapid, cost-effective passive seismic measurements to evaluate the variable thickness of the shallow colluvial and alluvial aquifer sediments along a headwater stream supporting cold water-dependent brook trout (Salvelinus fontinalis) in Shenandoah National Park, VA, USA. Using a mean depth to bedrock of 2.6 m, numerical models predicted strong sensitivity of shallow aquifer temperature to the downward propagation of surface heat. The annual temperature dynamics (annual signal amplitude attenuation and phase shift) of potential seepage sourced from the shallow modeled aquifer were compared to several years of paired observed stream and air temperature records. Annual stream water temperature patterns were found to lag local air temperature by ∼8–19 d along the stream corridor, indicating that thermal exchange between the stream and shallow groundwater is spatially variable. Locations with greater annual signal phase lag were also associated with locally increased amplitude attenuation, further suggestion of year-round buffering of channel water temperature by groundwater seepage. Numerical models of shallow groundwater temperature that incorporate regional expected climate warming trends indicate that the summer cooling capacity of this groundwater seepage will be reduced over time, and lower-elevation stream sections may no longer serve as larger

  3. Ecohydrological and subsurface controls on drought-induced contraction and disconnection of stream networks

    Science.gov (United States)

    Godsey, S.; Kirchner, J. W.; Whiting, J. A.

    2016-12-01

    Temporary headwater streams - both intermittent and ephemeral waterways - supply water to approximately 1/3 of the US population, and 60% of streams used for drinking water are temporary. Stream ecologists increasingly recognize that a gradient of processes across the drying continuum affect ecosystems at dynamic terrestrial-aquatic interfaces. Understanding the hydrological controls across that gradient of drying may improve management of these sensitive systems. One possible control on surface flows includes transpiration losses from either the riparian zone or the entire watershed. We mapped several stream networks under extreme low flow conditions brought on by severe drought in central Idaho and California in 2015. Compared to previous low-flow stream length estimates, the active drainage network had generally decreased by a very small amount across these sites, perhaps because stored water buffered the precipitation decrease, or because flowing channel heads are fixed by focused groundwater flow emerging at springs. We also examined the apparent sources of water for both riparian and hillslope trees using isotopic techniques. During drought conditions, we hypothesized that riparian trees - but not those far from flowing streams - would be sustained by streamflow recharging riparian aquifers, and thus would transpire water that was isotopically similar to streamflow because little soil water would remain available below the wilting point and stream water would be sustain those trees. We found a more complex pattern, but in most places stream water and water transpired by trees were isotopically distinct regardless of flow intermittency or tree location. We also found that hillslope trees outside of the riparian zone appeared to be using different waters from those used by riparian trees. Finally, we explore subsurface controls on network extent, showing that bedrock characteristics can influence network stability and contraction patterns.

  4. DNR 24K Streams

    Data.gov (United States)

    Minnesota Department of Natural Resources — 1:24,000 scale streams captured from USGS seven and one-half minute quadrangle maps, with perennial vs. intermittent classification, and connectivity through lakes,...

  5. Comparison of Organic Matter Composition in Agricultural versus Forest Affected Headwaters with Special Emphasis on Organic Nitrogen

    DEFF Research Database (Denmark)

    Heinz, Marlen; Graeber, Daniel; Zak, Dominik

    2015-01-01

    . By comparing six agriculturally and six forest-impacted headwater streams, we demonstrated that agriculture promotes increased DOC and DON concentrations, entailing an even more pronounced effect on DON. The major part of DOC and DON in agricultural and forest reference streams is exported in the form of humic...

  6. Leaf litter processing in West Virginia mountain streams: effects of temperature and stream chemistry

    Science.gov (United States)

    Jacquelyn M. Rowe; William B. Perry; Sue A. Perry

    1996-01-01

    Climate change has the potential to alter detrital processing in headwater streams, which receive the majority of their nutrient input as terrestrial leaf litter. Early placement of experimental leaf packs in streams, one month prior to most abscission, was used as an experimental manipulation to increase stream temperature during leaf pack breakdown. We studied leaf...

  7. Intermittent hydronephrosis

    International Nuclear Information System (INIS)

    Knop, J.; Vogel, H.; Hupe, W.

    1981-01-01

    An intermittent hydronephrosis was observed in a 40-year old patient. This disease pattern is due to an incongruity between the formation of urine and the transport capacity in the ureteropelvic junction. The latent impediment of flow becomes manifest with increased urine secretion. Irreversible renal damage can be the result of the repeatedly occurring hydronephrotic crises. (orig.) [de

  8. Applying four principles of headwater system aquatic biology to forest management

    Science.gov (United States)

    Robert J. Danehy; Sherri L. Johnson

    2013-01-01

    Headwater systems, including the channel and the adjacent riparian forest, are a dominant landscape feature in forested watersheds, draining most of the watershed area, and comprising the majority of channel length in drainage networks. Being at the upper extent of watersheds, these systems are smaller and steeper than large streams, and create microhabitats that...

  9. Temporal changes in fish species composition of headwater streams of the upper Paraguay and Paraná basins, Brazil = Alteração temporal na composição de espécies de peixes em riachos de cabeceira das bacias do alto Paraguai e Paraná, Brasil

    Directory of Open Access Journals (Sweden)

    Yzel Rondon Súarez

    2010-07-01

    Full Text Available This study was carried out in headwater streams in the Paraguay and Paraná river basins, with bi-monthly samples from January to November 2004, aiming to quantify the influence of environmental factors on the temporal rate of turnover in species composition of the fish communities. The environmental variables explained 73.5% of the variation in beta diversity and 52.5% of the variation in mean dissimilarity. Altitude was the only environmental descriptor that significantly explained the variation in beta diversity and mean dissimilarity in both basins.O presente estudo foi realizado em riachos de cabeceira nas bacias dos rios Paraguai e Paraná, por amostragens bimestrais de janeiro a novembro de 2004, com o objetivo de se quantificar a influência dos fatores ambientais sobre a taxa de alteração temporal na composição de espécies nas comunidades de peixes. As variáveis ambientais utilizadas explicaram 73,5% da variação na taxa de alteração na composição de espécies, utilizando a diversidade beta e 52,5% da variação na taxa de alteração pelo coeficiente de Jaccard. A altitude dos locais amostrados foi o único preditor significativo da taxa de alteração temporal na composição de espécies para ambas as bacias.

  10. Intermittency '93

    International Nuclear Information System (INIS)

    Bialas, A.

    1993-01-01

    The existing data definitely indicate the existence of intermittency, i.e. of self similar structures in the systems of particles created in high-energy collisions. The effect seems universal: it was found in most of the processes investigated and its measures parameters depend only weakly (if at all) on the process in question. Strong HBT effect was found, suggesting that intermittency is related to space-time structure of the pion source rather than to detailed momentum structure of the production amplitudes. There are indications that this space time structure may be fractal, but more data is needed to establish this. The theoretical explanation remains obscure: it seems that both parton cascade and hadronization play an important role. Their interrelation, however, remains a mystery. 5 figs., 19 refs

  11. Controls on dissolved organic matter (DOM) degradation in a headwater stream: the influence of photochemical and hydrological conditions in determining light-limitation or substrate-limitation of photo-degradation

    Science.gov (United States)

    Cory, R. M.; Harrold, K. H.; Neilson, B. T.; Kling, G. W.

    2015-11-01

    We investigated how absorption of sunlight by chromophoric dissolved organic matter (CDOM) controls the degradation and export of DOM from Imnavait Creek, a beaded stream in the Alaskan Arctic. We measured concentrations of dissolved organic carbon (DOC), as well as concentrations and characteristics of CDOM and fluorescent dissolved organic matter (FDOM), during ice-free periods of 2011-2012 in the pools of Imnavait Creek and in soil waters draining to the creek. Spatial and temporal patterns in CDOM and FDOM in Imnavait Creek were analyzed in conjunction with measures of DOM degradation by sunlight and bacteria and assessments of hydrologic residence times and in situ UV exposure. CDOM was the dominant light attenuating constituent in the UV and visible portion of the solar spectrum, with high attenuation coefficients ranging from 86 ± 12 m-1 at 305 nm to 3 ± 1 m-1 in the photosynthetically active region (PAR). High rates of light absorption and thus light attenuation by CDOM contributed to thermal stratification in the majority of pools in Imnavait Creek under low-flow conditions. In turn, thermal stratification increased the residence time of water and DOM, and resulted in a separation of water masses distinguished by contrasting UV exposure (i.e., UV attenuation by CDOM with depth resulted in bottom waters receiving less UV than surface waters). When the pools in Imnavait Creek were stratified, DOM in the pool bottom water closely resembled soil water DOM in character, while the concentration and character of DOM in surface water was reproduced by experimental photo-degradation of bottom water. These results, in combination with water column rates of DOM degradation by sunlight and bacteria, suggest that photo-degradation is the dominant process controlling DOM fate and export in Imnavait Creek. A conceptual model is presented showing how CDOM amount and lability interact with incident UV light and water residence time to determine whether photo

  12. Intermittent hyperthyreosis

    International Nuclear Information System (INIS)

    Sulman, F.G.; Tal, E.; Pfeifer, Y.; Superstine, E.

    1975-01-01

    Intermittent hyperthyreosis occurs under various forms of stress, especially heat stress. The clinician may diagnose such cases as masked or apathetic hyperthyroidism or 'forme fruste' hyperthyreosis or thyroid autonomy. As most routine and standard tests may here yield inconsistent results, it is the patients' anamnesis which may provide the clue. Our Bioclimatology Unit has now seen over 100 cases in which thyroid hypersensitivity towards heat was the most prominent syndrome: 10-15% of weather-sensitive patients are affected. The patients complain before or during heat spells of such contradictory symptoms as insomnia, irritability, tension, tachycardia, palpitations, precordial pain, dyspnoe, flushes with sweating or chills, tremor, abdominal pain or diarrhea, polyuria or pollakisuria, weight loss in spite of ravenous appetite, fatigue, exhaustion, depression, adynamia, lack of concentration and confusion. Determination of urinary neurohormones allows a differential diagnosis, intermittent hyperthyreosis being characterized by three cardinal symptoms: tachycardia - every case with more than 80 pulse beats being suspect (not specific); urinary histamine - every case excreting more than 90 μg/day being suspect. Again the drawback of this test is its lack of specificity, as histamine may also be increased in cases of allergy and spondylitis; urinary thyroxine - every case excreting more than 20 μg/day T-4 being suspect. This is the only specific test. Therapy should make use of lithium carbonate and betablockers. Propyl thiouracil is rarely required. (orig.) [de

  13. Peatland use and transport of particulate organic matter in boreal headwater catchments

    Science.gov (United States)

    Marttila, Hannu; Karjalainen, Satu-Maaria; Nieminen, Mika; Kløve, Bjørn

    2014-05-01

    Peatland use can cause increased transport of particulate organic matter (POM) causing deteriorated water quality and especially siltation of stream beds. Even though topic has gained major attention among stakeholders it has received only minor efforts to solve the main sources and properties of transported particles. The development of effective management practices and evaluation of purification efficiency demands understanding of the sources of particulate matter in peat dominated catchments with various land uses and hydrological conditions. The objectives of this study were: (1) to determinate physical properties of POM in headwater brooks affected by different peatland uses, and; (2) to identity the sources of transported material by using sediment fingerprinting methods. For this purpose, two headwater catchments under peat extraction and peatland forestry land uses with 8 sampling points were monitored for 2 years using time integrated suspended sediment samplers. Data was completed by gap samples from 50 other headwater locations with different upstream land uses: pristine, peatland forestry and peat extraction. For the sources analysis, disturbed topsoil, stream bed sediment, banks of ditches and brooks, algae and various vegetation types were identified as the potential sediment sources. Stable isotopes (δ13C, δ15N) and C/N ratio were analyzed to discriminate between the possible sources. Results are further scaled against different land uses, landscape elements and seasonal hydrological conditions in headwaters. This paper presents the preliminary results from a two year study aiming to show various patterns in transport of POM in boreal headwater catchments. Due to strong land-water relationship in headwaters, further information on the properties of particles is needed to assess the downstream impacts of land use.

  14. Perennial flow through convergent hillslopes explains chemodynamic solute behavior in a shale headwater catchment

    Science.gov (United States)

    Herndon, E.; Steinhoefel, G.; Dere, A. L. D.; Sullivan, P. L.

    2017-12-01

    Streams experience changing hydrologic connectivity to heterogeneous water sources under different flow regimes. It remains unclear how seasonal flow paths link these different sources and regulate concentration-discharge behavior. Previous research at the Susquehanna Shale Hills Critical Zone Observatory (SSHCZO) in central Pennsylvania, USA identified chemostatic solutes (e.g., K, Mg, Na, Cl) whose concentrations varied little across a wide range of discharge values and chemodynamic solutes (e.g., Fe and Mn) whose concentrations decreased sharply with increasing stream discharge. To elucidate inputs to the stream when concentrations of chemodynamic solutes were high, we investigated stream water and shallow groundwater (table remained over a meter below the stream bed along the rest of the channel. We conclude that well water sampled from the upper catchment is young, shallow interflow that upwells to generate metal-rich stream headwaters during the dry season. High concentrations of chemodynamic solutes measured during low discharge occur when metal-rich headwaters are flushed to the catchment outlet during periodic rain events. Interflow during the dry season originates from water that infiltrates through organic-rich swales; thus, metals in the stream at low flow are ultimately derived from convergent hillslopes where biological processes have concentrated chemodynamic elements. We infer that chemodynamic solutes are diluted at high discharge due to increased flow through planar hillslopes and inputs from regional groundwater that rises to enter the stream. This study highlights how spatially heterogeneous biogeochemistry and seasonally variable flow paths regulate concentration-discharge behavior within catchments.

  15. Leaf litter as a possible food source for chironomids (Diptera in Brazilian and Portuguese headwater streams Detritos foliares como possível fonte de alimento para Chironomidae (Diptera em riachos de cabeceira brasileiros e portugueses

    Directory of Open Access Journals (Sweden)

    Marcos Callisto

    2007-06-01

    Full Text Available Our objective was to evaluate the potential use of leaf detritus by chironomid larvae. Field and laboratory experiments were performed using leaves and chironomid species collected in Portugal and Brazil. Laboratory experiments under controlled conditions were done using microbial conditioned senescent leaves of Alnus glutinosa (L. Gaertn, Neriumoleander L., Protium heptaphilum (Aubl. March, Protium brasiliense (Spreng Engl., Myrcia guyanensis(Aubl. DC and Miconia chartacea Triana. Laboratory experiments were performed using specimens collected from leaf litter in local streams. Whenever possible, after the experiments, chironomids were allowed to emerge as adults and identified. In Portugal the following taxa were identified: Micropsectra apposita (Walker, 1856, Polypedilum albicorne (Meigen, 1838,Eukiefferiella claripennis Lundbeck (1898, Rheocricotopus (Psilocricotopus atripes Rempel (1937 and Ablabesmyia Johannsen (1905 (Diptera, Chironomidae. Consumption rates ranged from 0.15 ± 0.10 mg (AFDM of leaf animal-1 day-1 (Micropsectra apposita feeding on Alnus glutinosa up to 0.85 ± 0.33 mg (AFDM of leaf animal-1 day-1 (Polypedilum albicorne feeding on Miconia chartacea. In Brazil, the following taxa were identified from leaves: Phaenopsectra sp., Chironomus spp. and Polypedilum sp. and maximum consumption rates reached 0.47 ± 0.28 (AFDM of leaf mg.animal-1.day-1 (Chironomus Meigen (1803 feeding on Protium heptaphilum. Feeding experiments with laboratory cultured specimens, revealed that some chironomids were unable to feed on decomposing leaves (e.g., C. xanthus Rempel (1939 on P.brasiliensis and M.guyanensis. Our results suggest that some stream chironomids (not typical shredders can use leaf litter of riparian vegetation as a complementary food source.O objetivo foi avaliar o potencial uso de detritos foliares por larvas de Chironomidae. Foram realizados experimentos em campo e em laboratório utilizando folhas e larvas de Chironomidae

  16. Ground-water recharge from small intermittent streams in the western Mojave Desert, California: Chapter G in Ground-water recharge in the arid and semiarid southwestern United States (Professional Paper 1703)

    Science.gov (United States)

    Izbicki, John A.; Johnson, Russell U.; Kulongoski, Justin T.; Predmore, Steven; Stonestrom, David A.; Constantz, Jim; Ferré, Ty P.A.; Leake, Stanley A.

    2007-01-01

    Population growth has impacted ground-water resources in the western Mojave Desert, where declining water levels suggest that recharge rates have not kept pace with withdrawals. Recharge from the Mojave River, the largest hydrographic feature in the study area, is relatively well characterized. In contrast, recharge from numerous smaller streams that convey runoff from the bounding mountains is poorly characterized. The current study examined four representative streams to assess recharge from these intermittent sources. Hydraulic, thermal, geomorphic, chemical, and isotopic data were used to study recharge processes, from streamflow generation and infiltration to percolation through the unsaturated zone. Ground-water movement away from recharge areas was also assessed.Infiltration in amounts sufficient to have a measurable effect on subsurface temperature profiles did not occur in every year in instrumented study reaches. In addition to streamflow availability, results showed the importance of sediment texture in controlling infiltration and eventual recharge. Infiltration amounts of about 0.7 meters per year were an approximate threshold for the occurrence of ground-water recharge. Estimated travel times through the thick unsaturated zones underlying channels reached several hundred years. Recharging fluxes were influenced by stratigraphic complexity and depositional dynamics. Because of channel meandering, not all water that penetrates beneath the root zone can be assumed to become recharge on active alluvial fans.Away from study washes, elevated chloride concentrations and highly negative water potentials beneath the root zone indicated negligible recharge from direct infiltration of precipitation under current climatic conditions. In upstream portions of washes, generally low subsurface chloride concentrations and near-zero water potentials indicated downward movement of water toward the water table, driven primarily by gravity. Recharging conditions did not

  17. Age at sexual maturity, sex ratio, fecundity, and longevity of isolated headwater populations of westslope cutthroat trout

    Science.gov (United States)

    Christopher C. Downs; Robert G. White; Bradley B. Shepard

    1997-01-01

    We sampled 19 isolated headwater populations of westslope cutthroat trout Oncorhynchus clarki lewisi in Montana to provide estimates of fecundity, longevity, sex ratio, and age at sexual maturity. Fecundity was estimated for 31 fish collected from two streams in the upper Missouri River drainage. Females smaller than 149 mm fork length (FL) were generally immature and...

  18. Can structural and functional characteristics be used to identify riparian zone width in southern Appalachian headwater catchments?

    Science.gov (United States)

    Barton Clinton; James Vose; Jennifer Knoepp; Katherine Elliott; Barbara Reynolds; Stanley Zarnock

    2010-01-01

    We characterized structural and functional attributes along hillslope gradients in headwater catchments. We endeavored to identify parameters that described significant transitions along the hillslope. On each of four catchments, we installed eight 50 m transects perpendicular to the stream. Structural attributes included woody and herbaceous vegetation; woody debris...

  19. Influence of landscape position and transient water table on soil development and carbon distribution in a steep, headwater catchment

    Science.gov (United States)

    Scott W. Bailey; Patricia A. Brousseau; Kevin J. McGuire; Donald S. Ross

    2014-01-01

    Upland headwater catchments, such as those in the AppalachianMountain region, are typified by coarse textured soils, flashy hydrologic response, and low baseflow of streams, suggesting well drained soils and minimal groundwater storage. Model formulations of soil genesis, nutrient cycling, critical loads and rainfall/runoff response are typically based on vertical...

  20. Food Web Structure and Basal Resource Utilization along a Tropical Island Stream Continuum, Puerto Rico.

    Science.gov (United States)

    James G. March; Catherine M. Pringle

    2003-01-01

    Tropical stream food webs are thought to be based primarily on terrestrial resources (leaf litter) in small forested headwater streams and algal resources in larger, wider streams. In tropical island streams, the dominant consumers are often omnivorous freshwater shrimps that consume algae, leaf litter, insects, and other shrimps. We used stable isotope analysis...

  1. Efecto de la escorrentía sobre la carga de sedimentos en sus­pensión y fósforo en un arroyo de cabecera de una cuenca ru­ral (NO España Effect of runoff on suspended sediment and phosphorus loading in a headwater stream of a rural catchment (NW Spain

    Directory of Open Access Journals (Sweden)

    M.L. Rodríguez-Blanco

    2010-01-01

    Full Text Available Se determinó la carga de sedimentos en suspensión (SS y fósforo (P durante even­tos de lluvia-escorrentía en un arroyo de ca­becera, que drena una cuenca rural ubicada en Galicia (NO España. Asimismo, se trató de conocer las principales fuentes de SS y P exportados. Se observaron acusadas dife­rencias en la carga de SS y P entre eventos, lo cual se asocia con el volumen de esco­rrentía, así como con el desarrollo de surcos y cárcavas efímeras en parcelas de cultivo bien conectadas con la red de drenaje. La carga de SS osciló entre 0,8 y 21,0 t mientras que la de P varió entre 2,5 y 20,0 kg. El fósforo parti­culado (PP mostró relaciones significativas con los SS, lo que indica el origen erosivo de una parte importante de P, especialmente considerando que el PP supone más de un 80% del P exportado en cada evento.This work examines the suspended sedi­ment (SS and phosphorus (P load during rainfall-runoff events in a headwater stream which drains a rural catchment located in Galicia (NW Spain. Another objective is to know the major sources of SS and P ex­ported. Important differences in the SS and P load between events were found, which is associated with the runoff volume, as well as to develop of rills and ephemeral gullies in cultivated fields well connected to the drainage network. The SS load ranged be­tween 0.8 and 21.0 t, while the P load varied between 2.5 and 20.0 kg. The particulate phosphorus (PP showed significant rela­tionship with SS, which indicates the ero­sive origin of P, especially considering that PP means more 80% of P exported each event.

  2. Arthropod prey for riparian associated birds in headwater forests of the Oregon Coast Range

    Science.gov (United States)

    Hagar, Joan C.; Li, Judith; Sobota, Janel; Jenkins, Stephanie

    2012-01-01

    Headwater riparian areas occupy a large proportion of the land base in Pacific Northwest forests, and thus are ecologically and economically important. Although a primary goal of management along small headwater streams is the protection of aquatic resources, streamside habitat also is important for many terrestrial wildlife species. However, mechanisms underlying the riparian associations of some terrestrial species have not been well studied, particularly for headwater drainages. We investigated the diets of and food availability for four bird species associated with riparian habitats in montane coastal forests of western Oregon, USA. We examined variation in the availability of arthropod prey as a function of distance from stream. Specifically, we tested the hypotheses that (1) emergent aquatic insects were a food source for insectivorous birds in headwater riparian areas, and (2) the abundances of aquatic and terrestrial arthropod prey did not differ between streamside and upland areas during the bird breeding season. We found that although adult aquatic insects were available for consumption throughout the study period, they represented a relatively small proportion of available prey abundance and biomass and were present in only 1% of the diet samples from only one of the four riparian-associated bird species. Nonetheless, arthropod prey, comprised primarily of insects of terrestrial origin, was more abundant in streamside than upland samples. We conclude that food resources for birds in headwater riparian areas are primarily associated with terrestrial vegetation, and that bird distributions along the gradient from streamside to upland may be related to variation in arthropod prey availability. Because distinct vegetation may distinguish riparian from upland habitats for riparian-associated birds and their terrestrial arthropod prey, we suggest that understory communities be considered when defining management zones for riparian habitat.

  3. Controls on streamflow intermittence in the Colorado Front Range

    Science.gov (United States)

    Kampf, S. K.; Puntenney, K.; Martin, C.; Weber, R.; Gerlich, J.; Hammond, J. C.; Lefsky, M. A.

    2017-12-01

    Intermittent streams comprise more than 60% of the channel length in semiarid northern Colorado, yet little is known about their flow magnitude and timing. We used field surveys, stream sensors, and remote sensing to quantify spatial and temporal patterns of streamflow intermittence in the Cache la Poudre basin in 2016-2017. To evaluate potential controls on streamflow intermittence, we delineated the drainage area to each monitored point and quantified the catchment's mean precipitation, temperature, snow persistence, slope, aspect, vegetation type, soil type, and bedrock geology. During the period of study, most streams below 2500 m elevation and drainage areas >1 km2 had perennial flow, whereas nearly all streams with drainage areas <1 km2 had intermittent flow. For the high elevation intermittent streams, stream locations often differed substantially from the locations mapped in standard GIS data products. Initial analyses have identified no clearly quantifiable controls on flow duration of high elevation streams, but field observations indicate subsurface flow paths are important contributors to surface streams.

  4. Intermittency in Complex Flows

    Science.gov (United States)

    Ben Mahjoub, Otman; Redondo, Jose M.

    2017-04-01

    turbulent mixing is a subject of great importance because it has a broad range of practical applications. In the chemical industry in particular mixing is desirable to facilitate fast mixing of reactants coupled with PIV, and on other methods used in experimental fluids mechanics, both in Eulerian and Lagrangian frameworks towards the understanding of molecular mixing and the role of vorticity and helicity in the analysis of stream function parameter oundaries of spatial dynamic features. Already we used multi-fractal analysis techniques and apply these techniques to understand the scale to scale transport related to mixing and the velocity structure function,used by [1, 2] in the form ⟨| δul |p⟩ ∝ ⟨| δul |s⟩ζp/ζs where ζp/ζs is a general relative scaling exponent that can be expressed as dlog⟨| δul |p⟩ ζp/ζs = -----s- dlog⟨| δul | ⟩ In these relations ζp can be different from ξp for odd values of p because absolute values of velocity increments are used. Clearly, the scale-invariance for relative exponents when ζp and ζs are scale-dependent cannot be easily interpreted. We estimate different intermittency parameters as a function of local instability e.g. Kelvin/Helmholtz, Rayleigh-Taylor or Holbmoe. Different scalar interfaces show different structures, that also depend on local Richardsons numbers, this may be due to different levels of intermittency and thus different spectra, which are not necessarily inertial nor in equilibrium. the analysis of the statistical properties of the velocity structure function is performed using a relative scaling. In the areas of breaking-induced turbulence and foam, which corespond to active, highly intermittent, turbulent regions, using(ESS), we define local intermittency at different depths and horizontal positions. The deviation from the -5/3 law for the power spectra at certain positions is clear, (PDF) of velocity differences highly deviate from a gaussian distribution, and depend on the depth or with

  5. Dynamics of river sediments in forested headwater streams: Plynlimon

    Directory of Open Access Journals (Sweden)

    G. J. L. Leeks

    1997-01-01

    Full Text Available Long term studies of fluvial sediment processes in the Plynlimon catchments have contributed to the assessment and quantification of plantation forestry impacts in British upland catchments, at all stages of the forest cycle. The results from the Plynlimon studies are placed in the context of the observed impacts of particular forest practices and studies of forestry effects on sediment transport elsewhere in the world. The effects associated with drain excavation, ploughing, track construction, ground and channel disruption are outlined for both bedload and, particularly, for suspended load. Finally, recent data on sediment yields from 1995 to 1997 at Plynlimon are reported and discussed in the light of longer-term sediment yield estimates. This paper also provides background information relevant to other sediment process studies which use data from the main Plynlimon sediment monitoring network.

  6. Seasonal movement of Dolly Varden and cutthroat trout with respect to stream discharge in a second–order stream in South Alaska

    Science.gov (United States)

    M.D. Bryant; M.D. Lukey; J.P. McDonell; R.A. Gubernick; R.S. Aho

    2009-01-01

    The relationship between the movement of small (,150-mm) Dolly Varden Salvelinus malma and cutthroat trout Oncorhynchus clarkii and stream discharge is not well known in streams of southeast Alaska. We measured movement in a small headwater stream using passive integrated transponder (PIT) tags and stationary antennas to record time and date of movement. Fish with PIT...

  7. Comparisons of Spatial Predictions of Conductivity on a Stream Network in an Appalachian Watershed

    Science.gov (United States)

    We made spatial predictions of specific conductance based on spatial stream network (SSN) modeling to compare conductivity measurements of components of the network, such as headwaters, tributaries, and mainstem, which have different spatial extents in a study Appalachian watersh...

  8. NITROUS OXIDE CONCENTRATIONS IN SMALL STREAMS OF THE GEORGIA PIEDMONT

    Science.gov (United States)

    We are measuring the dissolved nitrous oxide concentration in 17 headwater streams in the South Fork Broad River, Georgia watershed on a monthly basis. The selected small streams drain watersheds dominated by forest, pasture, developed, or mixed land uses. Nitrous oxide concentr...

  9. Temporal and spatial variability in North Carolina piedmont stream temperature

    Science.gov (United States)

    J.L. Boggs; G. Sun; S.G. McNulty; W. Swartley; Treasure E.; W. Summer

    2009-01-01

    Understanding temporal and spatial patterns of in-stream temperature can provide useful information to managing future impacts of climate change on these systems. This study will compare temporal patterns and spatial variability of headwater in-stream temperature in six catchments in the piedmont of North Carolina in two different geological regions, Carolina slate...

  10. Sampling methods for amphibians in streams in the Pacific Northwest.

    Science.gov (United States)

    R. Bruce Bury; Paul Stephen. Corn

    1991-01-01

    Methods describing how to sample aquatic and semiaquatic amphibians in small streams and headwater habitats in the Pacific Northwest are presented. We developed a technique that samples 10-meter stretches of selected streams, which was adequate to detect presence or absence of amphibian species and provided sample sizes statistically sufficient to compare abundance of...

  11. Defining perennial, intermittent and ephemeral channels in eastern Kentucky: application to forestry best management practices

    Science.gov (United States)

    J. R. Svec; R. K. Kolka; J. W. Stringer

    2003-01-01

    In Kentucky stream classification is used to determine which forestry best management practice (BMP) to apply in riparian zones. Kentucky defines stream classes as follows (Stringer and others 1998): a) perennial streams that hold water throughout the year, b) intermittent streams that hold water during wet portions of the year, and c) ephemeral channels that hold...

  12. Effects of nutrient enrichment on the decomposition of wood and associated microbial activity in streams

    Science.gov (United States)

    Vladislav Gulis; Amy D. Rosemond; Keller Suberkropp; Holly S. Weyers; Jonathan P. Benstead

    2004-01-01

    We determined the effects of nutrient enrichment on wood decomposition rates and microbial activity during a 3-year study in two headwater streams at Coweeta Hydrologic Laboratory, NC, U.S.A. After a 1-year pretreatment period, one of the streams was continuously enriched with inorganic nutrients (nitrogen and phosphorus) for 2 years while the other stream served as a...

  13. Sensitivity of summer stream temperatures to climate variability in the Pacific Northwest

    Science.gov (United States)

    Charles Luce; Brian Staab; Marc Kramer; Seth Wenger; Dan Isaak; Callie McConnell

    2014-01-01

    Estimating the thermal response of streams to a warming climate is important for prioritizing native fish conservation efforts. While there are plentiful estimates of air temperature responses to climate change, the sensitivity of streams, particularly small headwater streams, to warming temperatures is less well understood. A substantial body of literature correlates...

  14. Work Element B: 157. Sampling in Fish-Bearing Reaches [Variation in Productivity in Headwater Reaches of the Wenatchee Subbasin], Final Report for PNW Research Station.

    Energy Technology Data Exchange (ETDEWEB)

    Polivka, Karl; Bennett, Rita L. [USDA Forest Service, Pacific Northwest Research Station, Wenatchee, WA

    2009-03-31

    We studied variation in productivity in headwater reaches of the Wenatchee subbasin for multiple field seasons with the objective that we could develop methods for monitoring headwater stream conditions at the subcatchment and stream levels, assign a landscape-scale context via the effects of geoclimatic parameters on biological productivity (macroinvertebrates and fish) and use this information to identify how variability in productivity measured in fishless headwaters is transmitted to fish communities in downstream habitats. In 2008, we addressed this final objective. In collaboration with the University of Alaska Fairbanks we found some broad differences in the production of aquatic macroinvertebrates and in fish abundance across categories that combine the effects of climate and management intensity within the subbasin (ecoregions). From a monitoring standpoint, production of benthic macroinvertebrates was not a good predictor of drifting macroinvertebrates and therefore might be a poor predictor of food resources available to fish. Indeed, there is occasionally a correlation between drifting macroinvertebrate abundance and fish abundance which suggests that headwater-derived resources are important. However, fish in the headwaters appeared to be strongly food-limited and there was no evidence that fishless headwaters provided a consistent subsidy to fish in reaches downstream. Fish abundance and population dynamics in first order headwaters may be linked with similar metrics further down the watershed. The relative strength of local dynamics and inputs into productivity may be constrained or augmented by large-scale biogeoclimatic control. Headwater streams are nested within watersheds, which are in turn nested within ecological subregions; thus, we hypothesized that local effects would not necessarily be mutually exclusive from large-scale influence. To test this we examined the density of primarily salmonid fishes at several spatial and temporal scales

  15. Retrospective Analysis of Low Flows at Headwater Watersheds in Wyoming

    Science.gov (United States)

    Voutchkova, D. D.; Miller, S. N.

    2016-12-01

    Understanding summer low-flow variability and change in the mountainous West has important implications for water allocations downstream and for maintaining water availability for drinking water supply, reservoir storage, industrial, agricultural, and ecological needs. Wildfires and insect infestations are classical disturbance hydrology topics. It is unclear, however, what are their effects on streamflow and in particular low-flows, when vegetation disturbances are overlapping in time and combined with highly variable and potentially changing local climate. The purpose of this study, therefore, is to quantify changes in low-flows resulting from disturbance in headwater streams. Here we present a retrospective analysis based on: (1) 49-75 complete water years (wy) of daily streamflow data (USGS) for 14 high-elevation headwater watersheds with varying areas (60-1730 km2, 86-100% of watershed area >2000masl) and evergreen forest cover (15-82%), (2) 25-36 complete wy of daily snow-water equivalent accumulation (SWE) and precipitation data from Wyoming SNOTEL stations, (3) burned area boundaries for 20wy (MTBS project), (4) aerial surveys by R1, R2, R4 Forest Service Regions for 18wy (data on tree mortality). We quantify the change in various low-flow characteristics (e.g. post-snowmelt baseflow, Q90 and Q95, 3-,7-, 30- and 90-day annual minima etc.) while accounting for local inter- and multi-annual climate variability by using SWE accumulation data, as it integrates both temperature and precipitation changes. Our approach differs from typical before-after field-based investigation for paired watersheds, as it provides a synthesis over large temporal and spatial scales, resulting in spectrum of possible hydrologic responses due to varying disturbance severity. Quantifying the changes in low-flows and low-flow variability will improve our understanding and will facilitate water management and planning at local state-wide level.

  16. Intermittent search strategies

    Science.gov (United States)

    Bénichou, O.; Loverdo, C.; Moreau, M.; Voituriez, R.

    2011-01-01

    This review examines intermittent target search strategies, which combine phases of slow motion, allowing the searcher to detect the target, and phases of fast motion during which targets cannot be detected. It is first shown that intermittent search strategies are actually widely observed at various scales. At the macroscopic scale, this is, for example, the case of animals looking for food; at the microscopic scale, intermittent transport patterns are involved in a reaction pathway of DNA-binding proteins as well as in intracellular transport. Second, generic stochastic models are introduced, which show that intermittent strategies are efficient strategies that enable the minimization of search time. This suggests that the intrinsic efficiency of intermittent search strategies could justify their frequent observation in nature. Last, beyond these modeling aspects, it is proposed that intermittent strategies could also be used in a broader context to design and accelerate search processes.

  17. Oscillating acoustic streaming jet

    International Nuclear Information System (INIS)

    Moudjed, Brahim; Botton, Valery; Henry, Daniel; Millet, Severine; Ben Hadid, Hamda; Garandet, Jean-Paul

    2014-01-01

    The present paper provides the first experimental investigation of an oscillating acoustic streaming jet. The observations are performed in the far field of a 2 MHz circular plane ultrasound transducer introduced in a rectangular cavity filled with water. Measurements are made by Particle Image Velocimetry (PIV) in horizontal and vertical planes near the end of the cavity. Oscillations of the jet appear in this zone, for a sufficiently high Reynolds number, as an intermittent phenomenon on an otherwise straight jet fluctuating in intensity. The observed perturbation pattern is similar to that of former theoretical studies. This intermittently oscillatory behavior is the first step to the transition to turbulence. (authors)

  18. Determinantes ambientais da ocorrência de espécies de peixes em riachos de cabeceira da bacia do rio Ivinhema, alto rio Paraná - DOI: 10.4025/actascibiolsci.v29i2.520 Environmental determinants of fish species occurrence in headwaters streams of Ivinhema river basin, upper Paraná river - DOI: 10.4025/actascibiolsci.v29i2.520

    Directory of Open Access Journals (Sweden)

    Thiago Rota Alves Felipe

    2007-12-01

    Full Text Available Com o objetivo de quantificar a importância de algumas características fisiográficas dos riachos sobre a ocorrência de quatro espécies de Characidae em riachos de cabeceira na bacia do rio Ivinhema, realizaram-se amostragens bimestrais em dez riachos com uso de telas de isca, com esforço amostral padronizado. A influência das variáveis ambientais sobre a ocorrência das espécies de peixes foi quantificada utilizando-se do modelo da análise de regressão logística. Constatou-se que a velocidade da correnteza foi o principal fator limitante da ocorrência de Serrapinnus notomelas, Hemigrammus marginatus e Moenkhausia sanctaefilomenae, enquanto a profundidade dos riachos foi o principal determinante da ocorrência de Bryconamericus stramineus. Assim, as primeiras espécies ocorrem predominantemente em locais com baixa velocidade da correnteza, enquanto B. stramineus ocorre principalmente em locais com pouca profundidade e com elevada velocidade da correnteza, sugerindo que as características fisiográficas dos habitat sejam importantes determinantes da colonização e persistência das espécies. Palavras-chave: distribuição espacial, peixes de riachos, bacia do rio Ivinhema.In order to quantify the importance of some physiographic characteristics of headwaters streams of Ivinhema basin on occurrence of four Characidae species, bimonthly samples in 10 streams using a rectangular sieve, with standardized sampling effort were collected. The influence of environmental descriptors on species occurrence was quantified using a logistic regression model. It was observed that the water velocity was the main limiting factor to occurrence of Serrapinnus notomelas, Hemigrammus marginatus and Moenkhausia sanctaefilomenae while stream depth was the main determinant of Bryconamericus stramineus occurrence. Thus, the first three species are found mainly in sites with less water velocity, while B. stramineus is found mainly in sites with less depth

  19. Estimating benthic secondary production from aquatic insect emergence in streams affected by mountaintop removal coal mining, West Virginia USA

    Science.gov (United States)

    Mountaintop removal and valley fill (MTR/VF) coal mining recountours the Appalachian landscape, buries headwater stream channels, and degrades downstream water quality. The goal of this study was to compare benthic community production estimates, based on seasonal insect emergen...

  20. Sibship reconstruction for inferring mating systems, dispersal and effective population size in headwater brook trout (Salvelinus fontinalis) populations

    Science.gov (United States)

    Kanno, Yoichiro; Vokoun, Jason C.; Letcher, Benjamin H.

    2011-01-01

    Brook trout Salvelinus fontinalis populations have declined in much of the native range in eastern North America and populations are typically relegated to small headwater streams in Connecticut, USA. We used sibship reconstruction to infer mating systems, dispersal and effective population size of resident (non-anadromous) brook trout in two headwater stream channel networks in Connecticut. Brook trout were captured via backpack electrofishing using spatially continuous sampling in the two headwaters (channel network lengths of 4.4 and 7.7 km). Eight microsatellite loci were genotyped in a total of 740 individuals (80–140 mm) subsampled in a stratified random design from all 50 m-reaches in which trout were captured. Sibship reconstruction indicated that males and females were both mostly polygamous although single pair matings were also inferred. Breeder sex ratio was inferred to be nearly 1:1. Few large-sized fullsib families (>3 individuals) were inferred and the majority of individuals were inferred to have no fullsibs among those fish genotyped (family size = 1). The median stream channel distance between pairs of individuals belonging to the same large-sized fullsib families (>3 individuals) was 100 m (range: 0–1,850 m) and 250 m (range: 0–2,350 m) in the two study sites, indicating limited dispersal at least for the size class of individuals analyzed. Using a sibship assignment method, the effective population size for the two streams was estimated at 91 (95%CI: 67–123) and 210 (95%CI: 172–259), corresponding to the ratio of effective-to-census population size of 0.06 and 0.12, respectively. Both-sex polygamy, low variation in reproductive success, and a balanced sex ratio may help maintain genetic diversity of brook trout populations with small breeder sizes persisting in headwater channel networks.

  1. Intermittency in branching models

    International Nuclear Information System (INIS)

    Chiu, C.B.; Texas Univ., Austin; Hwa, R.C.; Oregon Univ., Eugene

    1990-01-01

    The intermittency properties of three branching models have been investigated. The factorial moments show power-law behavior as function of small rapidity width. The slopes and energy dependences reveal different characteristics of the models. The gluon model has the weakest intermittency. (orig.)

  2. Intermittent degradation and schizotypy

    Directory of Open Access Journals (Sweden)

    Matthew W. Roché

    2015-06-01

    Full Text Available Intermittent degradation refers to transient detrimental disruptions in task performance. This phenomenon has been repeatedly observed in the performance data of patients with schizophrenia. Whether intermittent degradation is a feature of the liability for schizophrenia (i.e., schizotypy is an open question. Further, the specificity of intermittent degradation to schizotypy has yet to be investigated. To address these questions, 92 undergraduate participants completed a battery of self-report questionnaires assessing schizotypy and psychological state variables (e.g., anxiety, depression, and their reaction times were recorded as they did so. Intermittent degradation was defined as the number of times a subject’s reaction time for questionnaire items met or exceeded three standard deviations from his or her mean reaction time after controlling for each item’s information processing load. Intermittent degradation scores were correlated with questionnaire scores. Our results indicate that intermittent degradation is associated with total scores on measures of positive and disorganized schizotypy, but unrelated to total scores on measures of negative schizotypy and psychological state variables. Intermittent degradation is interpreted as potentially derivative of schizotypy and a candidate endophenotypic marker worthy of continued research.

  3. Quantifying spatial and temporal patterns of flow intermittency using spatially contiguous runoff data

    Science.gov (United States)

    Yu (于松延), Songyan; Bond, Nick R.; Bunn, Stuart E.; Xu, Zongxue; Kennard, Mark J.

    2018-04-01

    River channel drying caused by intermittent stream flow is a widely-recognized factor shaping stream ecosystems. There is a strong need to quantify the distribution of intermittent streams across catchments to inform management. However, observational gauge networks provide only point estimates of streamflow variation. Increasingly, this limitation is being overcome through the use of spatially contiguous estimates of the terrestrial water-balance, which can also assist in estimating runoff and streamflow at large-spatial scales. Here we proposed an approach to quantifying spatial and temporal variation in monthly flow intermittency throughout river networks in eastern Australia. We aggregated gridded (5 × 5 km) monthly water-balance data with a hierarchically nested catchment dataset to simulate catchment runoff accumulation throughout river networks from 1900 to 2016. We also predicted zero flow duration for the entire river network by developing a robust predictive model relating measured zero flow duration (% months) to environmental predictor variables (based on 43 stream gauges). We then combined these datasets by using the predicted zero flow duration from the regression model to determine appropriate 'zero' flow thresholds for the modelled discharge data, which varied spatially across the catchments examined. Finally, based on modelled discharge data and identified actual zero flow thresholds, we derived summary metrics describing flow intermittency across the catchment (mean flow duration and coefficient-of-variation in flow permanence from 1900 to 2016). We also classified the relative degree of flow intermittency annually to characterise temporal variation in flow intermittency. Results showed that the degree of flow intermittency varied substantially across streams in eastern Australia, ranging from perennial streams flowing permanently (11-12 months) to strongly intermittent streams flowing 4 months or less of year. Results also showed that the

  4. Potential stream density in Mid-Atlantic US watersheds.

    Science.gov (United States)

    Elmore, Andrew J; Julian, Jason P; Guinn, Steven M; Fitzpatrick, Matthew C

    2013-01-01

    Stream network density exerts a strong influence on ecohydrologic processes in watersheds, yet existing stream maps fail to capture most headwater streams and therefore underestimate stream density. Furthermore, discrepancies between mapped and actual stream length vary between watersheds, confounding efforts to understand the impacts of land use on stream ecosystems. Here we report on research that predicts stream presence from coupled field observations of headwater stream channels and terrain variables that were calculated both locally and as an average across the watershed upstream of any location on the landscape. Our approach used maximum entropy modeling (MaxEnt), a robust method commonly implemented to model species distributions that requires information only on the presence of the entity of interest. In validation, the method correctly predicts the presence of 86% of all 10-m stream segments and errors are low (stream density and compare our results with the National Hydrography Dataset (NHD). We find that NHD underestimates stream density by up to 250%, with errors being greatest in the densely urbanized cities of Washington, DC and Baltimore, MD and in regions where the NHD has never been updated from its original, coarse-grain mapping. This work is the most ambitious attempt yet to map stream networks over a large region and will have lasting implications for modeling and conservation efforts.

  5. Mechanisms of carbon storage in mountainous headwater rivers

    Science.gov (United States)

    Ellen Wohl; Kathleen Dwire; Nicholas Sutfin; Lina Polvi; Roberto Bazan

    2012-01-01

    Published research emphasizes rapid downstream export of terrestrial carbon from mountainous headwater rivers, but little work focuses on mechanisms that create carbon storage along these rivers, or on the volume of carbon storage. Here we estimate organic carbon stored in diverse valley types of headwater rivers in Rocky Mountain National Park, CO, USA. We show that...

  6. Intermittent Explosive Disorder

    Directory of Open Access Journals (Sweden)

    Lut Tamam

    2011-09-01

    Full Text Available Intermittent explosive disorder is an impulse control disorder characterized by the occurrence of discrete episodes of failure to resist aggressive impulses that result in violent assault or destruction of property. Though the prevalence intermittent explosive disorder has been reported to be relatively rare in frontier studies on the field, it is now common opinion that intermittent explosive disorder is far more common than previously thought especially in clinical psychiatry settings. Etiological studies displayed the role of both psychosocial factors like childhood traumas and biological factors like dysfunctional neurotransmitter systems and genetics. In differential diagnosis of the disorder, disorders involving agression as a symptom such as alcohol and drug intoxication, antisocial and borderline personality disorders, personality changes due to general medical conditions and behavioral disorder should be considered. A combination of pharmacological and psychotherapeutic approaches are suggested in the treatment of the disorder. This article briefly reviews the historical background, diagnostic criteria, epidemiology, etiology and treatment of intermittent explosive disorder.

  7. Intermittent heating of buildings

    Energy Technology Data Exchange (ETDEWEB)

    Kohonen, K

    1983-02-01

    Conditions for intermittent heating of buildings are considered both theoretically and experimentally. Thermal behaviour of buildings adn rooms in intermittent heating is simulated by a program based on the convective heat balance equation and by simplified RC-models. The preheat times and the heating energy savings compared with continuous heating are presented for typical lightweight, mediumweight and heavyweight classroom and office modules. Formulaes for estimating the oversizing of the radiator network, the maximum heat output of heat exchangers in district heating and the efficiency of heating boilers in intermittent heating are presented. The preheat times and heating energy savings with different heating control systems are determined also experimentally in eight existing buildings. In addition some principles for the planning and application of intermittent heating systems are suggested.

  8. Relationship Between Storm Hydrograph Components and Subsurface Flow Processes in a Hilly Headwater Basin, Toyota, Japan

    Science.gov (United States)

    Tsujimura, M.; Asai, K.; Takei, R.

    2001-05-01

    Temporal and spatial distribution of tracer elements and subsurface flow processes were investigated to study relationship between storm hydrograph components and behavior of subsurface water in a headwater catchment of Toyota Hill, Aichi prefecture, central Japan. The catchment has an area of 0.857 ha with an altitude of 60 to 100 m, and is underlain by granite. The soil depth revealed by sounding test ranges from 0.5 to 4.0 m. Rain, stream, soil and ground waters were sampled once in a week, and the stream water was sampled at 5 to 60 minute intervals during rainstorms. The pressure head of subsurface water was monitored using tensiometers and piezometers nests, and the stream flow was monitored using V-notch weir. The stable isotopic ratios of deuterium and oxygen 18 and inorganic ion concentrations were determined on all water samples. The oxygen 18 isotopic ratio in stream water decreased with rainfall during the rainstorms. The ratio of event water component to the total runoff water at the peak discharge ranged from 16 to 92 %, and the event water ratio correlated with the peak discharge rate and rainfall intensity. The tesiometric data showed that the shallow subsurface water with low isotopic ratios at the lower slope discharged directly to the stream during the heavy rainstorms. The shallow subsurface flow at the lower slope and overland flow on the raiparian zone contributed much to the stream water chemistry during heavy rainstorms.

  9. Optimal intermittent search strategies

    International Nuclear Information System (INIS)

    Rojo, F; Budde, C E; Wio, H S

    2009-01-01

    We study the search kinetics of a single fixed target by a set of searchers performing an intermittent random walk, jumping between different internal states. Exploiting concepts of multi-state and continuous-time random walks we have calculated the survival probability of a target up to time t, and have 'optimized' (minimized) it with regard to the transition probability among internal states. Our model shows that intermittent strategies always improve target detection, even for simple diffusion states of motion

  10. Fine-scale population structure and riverscape genetics of brook trout (Salvelinus fontinalis) distributed continuously along headwater channel networks

    Science.gov (United States)

    Kanno, Yoichiro; Vokoun, Jason C.; Letcher, Benjamin H.

    2011-01-01

    Linear and heterogeneous habitat makes headwater stream networks an ideal ecosystem in which to test the influence of environmental factors on spatial genetic patterns of obligatory aquatic species. We investigated fine-scale population structure and influence of stream habitat on individual-level genetic differentiation in brook trout (Salvelinus fontinalis) by genotyping eight microsatellite loci in 740 individuals in two headwater channel networks (7.7 and 4.4 km) in Connecticut, USA. A weak but statistically significant isolation-by-distance pattern was common in both sites. In the field, many tagged individuals were recaptured in the same 50-m reaches within a single field season (summer to fall). One study site was characterized with a hierarchical population structure, where seasonal barriers (natural falls of 1.5–2.5 m in height during summer base-flow condition) greatly reduced gene flow and perceptible spatial patterns emerged because of the presence of tributaries, each with a group of genetically distinguishable individuals. Genetic differentiation increased when pairs of individuals were separated by high stream gradient (steep channel slope) or warm stream temperature in this site, although the evidence of their influence was equivocal. In a second site, evidence for genetic clusters was weak at best, but genetic differentiation between individuals was positively correlated with number of tributary confluences. We concluded that the population-level movement of brook trout was limited in the study headwater stream networks, resulting in the fine-scale population structure (genetic clusters and clines) even at distances of a few kilometres, and gene flow was mitigated by ‘riverscape’ variables, particularly by physical barriers, waterway distance (i.e. isolation-by-distance) and the presence of tributaries.

  11. The role of remediation, natural alkalinity sources and physical stream parameters in stream recovery.

    Science.gov (United States)

    Kruse, Natalie A; DeRose, Lisa; Korenowsky, Rebekah; Bowman, Jennifer R; Lopez, Dina; Johnson, Kelly; Rankin, Edward

    2013-10-15

    Acid mine drainage (AMD) negatively impacts not only stream chemistry, but also aquatic biology. The ultimate goal of AMD treatment is restoration of the biological community, but that goal is rarely explicit in treatment system design. Hewett Fork in Raccoon Creek Watershed, Ohio, has been impacted by historic coal mining and has been treated with a calcium oxide doser in the headwaters of the watershed since 2004. All of the acidic inputs are isolated to a 1.5 km stretch of stream in the headwaters of the Hewett Fork watershed. The macroinvertebrate and fish communities have begun to recover and it is possible to distinguish three zones downstream of the doser: an impaired zone, a transition zone and a recovered zone. Alkalinity from both the doser and natural sources and physical stream parameters play a role in stream restoration. In Hewett Fork, natural alkaline additions downstream are higher than those from the doser. Both, alkaline additions and stream velocity drive sediment and metal deposition. Metal deposition occurs in several patterns; aluminum tends to deposit in regions of low stream velocity, while iron tends to deposit once sufficient alkalinity is added to the system downstream of mining inputs. The majority of metal deposition occurs upstream of the recovered zone. Both the physical stream parameters and natural alkalinity sources influence biological recovery in treated AMD streams and should be considered in remediation plans. Copyright © 2013 Elsevier Ltd. All rights reserved.

  12. NITRATE AND NITROUS OXIDE CONCENTRATIONS IN SMALL STREAMS OF THE GEORGIA PIEDMONT

    Science.gov (United States)

    We are measuring dissolved nitrate and nitrous oxide concentrations and related parameters in 17 headwater streams in the South Fork Broad River, Georgia watershed on a monthly basis. The selected small streams drain watersheds dominated by forest, pasture, residential, or mixed...

  13. Consumer-resource stoichiometry in detritus-based streams

    Science.gov (United States)

    Wyatt F. Cross; Jonathan P. Benstead; Amy D. Rosemond; J. Bruce Wallace

    2003-01-01

    Stoichiometric relationships between consumers and resources in detritus-based ecosystems have received little attention, despite the importance of detritus in most food webs. We analysed carbon (C), nitrogen (N), and phosphorus (P) content of invertebrate consumers, and basal food resources in two forested headwater streams (one reference and the other nutrient-...

  14. Stream water responses to timber harvest: Riparian buffer width effectiveness

    Science.gov (United States)

    Barton D. Clinton

    2011-01-01

    Vegetated riparian buffers are critical for protecting aquatic and terrestrial processes and habitats in southern Appalachian ecosystems. In this case study, we examined the effect of riparian buffer width on stream water quality following upland forest management activities in four headwater catchments. Three riparian buffer widths were delineated prior to cutting; 0m...

  15. Mean transit times in headwater catchments: insights from the Otway Ranges, Australia

    Directory of Open Access Journals (Sweden)

    W. Howcroft

    2018-01-01

    Full Text Available Understanding the timescales of water flow through catchments and the sources of stream water at different flow conditions is critical for understanding catchment behaviour and managing water resources. Here, tritium (3H activities, major ion geochemistry and streamflow data were used in conjunction with lumped parameter models (LPMs to investigate mean transit times (MTTs and the stores of water in six headwater catchments in the Otway Ranges of southeastern Australia. 3H activities of stream water ranged from 0.20 to 2.14 TU, which are significantly lower than the annual average 3H activity of modern local rainfall, which is between 2.4 and 3.2 TU. The 3H activities of the stream water are lowest during low summer flows and increase with increasing streamflow. The concentrations of most major ions vary little with streamflow, which together with the low 3H activities imply that there is no significant direct input of recent rainfall at the streamflows sampled in this study. Instead, shallow younger water stores in the soils and regolith are most likely mobilised during the wetter months. MTTs vary from approximately 7 to 230 years. Despite uncertainties of several years in the MTTs that arise from having to assume an appropriate LPM, macroscopic mixing, and uncertainties in the 3H activities of rainfall, the conclusion that they range from years to decades is robust. Additionally, the relative differences in MTTs at different streamflows in the same catchment are estimated with more certainty. The MTTs in these and similar headwater catchments in southeastern Australia are longer than in many catchments globally. These differences may reflect the relatively low rainfall and high evapotranspiration rates in southeastern Australia compared with headwater catchments elsewhere. The long MTTs imply that there is a long-lived store of water in these catchments that can sustain the streams over drought periods lasting several years. However, the

  16. Mean transit times in headwater catchments: insights from the Otway Ranges, Australia

    Science.gov (United States)

    Howcroft, William; Cartwright, Ian; Morgenstern, Uwe

    2018-01-01

    Understanding the timescales of water flow through catchments and the sources of stream water at different flow conditions is critical for understanding catchment behaviour and managing water resources. Here, tritium (3H) activities, major ion geochemistry and streamflow data were used in conjunction with lumped parameter models (LPMs) to investigate mean transit times (MTTs) and the stores of water in six headwater catchments in the Otway Ranges of southeastern Australia. 3H activities of stream water ranged from 0.20 to 2.14 TU, which are significantly lower than the annual average 3H activity of modern local rainfall, which is between 2.4 and 3.2 TU. The 3H activities of the stream water are lowest during low summer flows and increase with increasing streamflow. The concentrations of most major ions vary little with streamflow, which together with the low 3H activities imply that there is no significant direct input of recent rainfall at the streamflows sampled in this study. Instead, shallow younger water stores in the soils and regolith are most likely mobilised during the wetter months. MTTs vary from approximately 7 to 230 years. Despite uncertainties of several years in the MTTs that arise from having to assume an appropriate LPM, macroscopic mixing, and uncertainties in the 3H activities of rainfall, the conclusion that they range from years to decades is robust. Additionally, the relative differences in MTTs at different streamflows in the same catchment are estimated with more certainty. The MTTs in these and similar headwater catchments in southeastern Australia are longer than in many catchments globally. These differences may reflect the relatively low rainfall and high evapotranspiration rates in southeastern Australia compared with headwater catchments elsewhere. The long MTTs imply that there is a long-lived store of water in these catchments that can sustain the streams over drought periods lasting several years. However, the catchments are likely

  17. Regional Curve Development and Use in Stream Restoration and Hydrologic Assessment in High Gradient Headwater Streams

    Science.gov (United States)

    Introduction to Regional Curves including; regressions relating bankfull channelcharacteristics to drainage area, providing estimates of bankfull discharge and channel geometry, validating the selection of the bankfull channel as determined in the field

  18. Hierarchical spatial structure of stream fish colonization and extinction

    Science.gov (United States)

    Hitt, N.P.; Roberts, J.H.

    2012-01-01

    Spatial variation in extinction and colonization is expected to influence community composition over time. In stream fish communities, local species richness (alpha diversity) and species turnover (beta diversity) are thought to be regulated by high extinction rates in headwater streams and high colonization rates in downstream areas. We evaluated the spatiotemporal structure of fish communities in streams originally surveyed by Burton and Odum 1945 (Ecology 26: 182-194) in Virginia, USA and explored the effects of species traits on extinction and colonization dynamics. We documented dramatic changes in fish community structure at both the site and stream scales. Of the 34 fish species observed, 20 (59%) were present in both time periods, but 11 (32%) colonized the study area and three (9%) were extirpated over time. Within streams, alpha diversity increased in two of three streams but beta diversity decreased dramatically in all streams due to fish community homogenization caused by colonization of common species and extirpation of rare species. Among streams, however, fish communities differentiated over time. Regression trees indicated that reproductive life-history traits such as spawning mound construction, associations with mound-building species, and high fecundity were important predictors of species persistence or colonization. Conversely, native fishes not associated with mound-building exhibited the highest rates of extirpation from streams. Our results demonstrate that stream fish colonization and extinction dynamics exhibit hierarchical spatial structure and suggest that mound-building fishes serve as keystone species for colonization of headwater streams.

  19. Flow intermittence and ecosystem services in rivers of the Anthropocene

    Science.gov (United States)

    Intermittent rivers and ephemeral streams (IRES) are watercourses that cease flow at some point in time and space. Arguably Earth's most widespread type of flowing water, IRES are expanding where Anthropocenic climates grow drier and human demands for water escalate. However, IRE...

  20. Assessment of Streamside Management Zones for Conserving Benthic Macroinvertebrate Communities Following Timber Harvest in Eastern Kentucky Headwater Catchments

    Directory of Open Access Journals (Sweden)

    Joshua K. Adkins

    2016-06-01

    Full Text Available Headwater streams generally comprise the majority of stream area in a watershed and can have a strong influence on downstream food webs. Our objective was to determine the effect of altering streamside management zone (SMZ configurations on headwater aquatic insect communities. Timber harvests were implemented within six watersheds in eastern Kentucky. The SMZ configurations varied in width, canopy retention and best management practice (BMP utilization at the watershed scale. Benthic macroinvertebrate samples collected one year before and four years after harvest indicated few differences among treatments, although post-treatment abundance was elevated in some of the treatment streams relative to the unharvested controls. Jaccard index values were similar across SMZ treatments after logging, indicating strong community overlap. These findings suggest that stream invertebrate communities did respond to the timber harvest, though not negatively. Results also suggest that SMZ criteria for aquatic habitats in steeply sloping topography, including at least 50 percent canopy retention and widths of at least 16.8 m, appear to be adequate for protecting benthic macroinvertebrate communities from logging impacts.

  1. Optimal intermittent search strategies

    Energy Technology Data Exchange (ETDEWEB)

    Rojo, F; Budde, C E [FaMAF, Universidad Nacional de Cordoba, Ciudad Universitaria, X5000HUA Cordoba (Argentina); Wio, H S [Instituto de Fisica de Cantabria, Universidad de Cantabria and CSIC E-39005 Santander (Spain)

    2009-03-27

    We study the search kinetics of a single fixed target by a set of searchers performing an intermittent random walk, jumping between different internal states. Exploiting concepts of multi-state and continuous-time random walks we have calculated the survival probability of a target up to time t, and have 'optimized' (minimized) it with regard to the transition probability among internal states. Our model shows that intermittent strategies always improve target detection, even for simple diffusion states of motion.

  2. Intermittency and random matrices

    Science.gov (United States)

    Sokoloff, Dmitry; Illarionov, E. A.

    2015-08-01

    A spectacular phenomenon of intermittency, i.e. a progressive growth of higher statistical moments of a physical field excited by an instability in a random medium, attracted the attention of Zeldovich in the last years of his life. At that time, the mathematical aspects underlying the physical description of this phenomenon were still under development and relations between various findings in the field remained obscure. Contemporary results from the theory of the product of independent random matrices (the Furstenberg theory) allowed the elaboration of the phenomenon of intermittency in a systematic way. We consider applications of the Furstenberg theory to some problems in cosmology and dynamo theory.

  3. Factoring stream turbulence into global assessments of nitrogen pollution.

    Science.gov (United States)

    Grant, Stanley B; Azizian, Morvarid; Cook, Perran; Boano, Fulvio; Rippy, Megan A

    2018-03-16

    The discharge of excess nitrogen to streams and rivers poses an existential threat to both humans and ecosystems. A seminal study of headwater streams across the United States concluded that in-stream removal of nitrate is controlled primarily by stream chemistry and biology. Reanalysis of these data reveals that stream turbulence (in particular, turbulent mass transfer across the concentration boundary layer) imposes a previously unrecognized upper limit on the rate at which nitrate is removed from streams. The upper limit closely approximates measured nitrate removal rates in streams with low concentrations of this pollutant, a discovery that should inform stream restoration designs and efforts to assess the effects of nitrogen pollution on receiving water quality and the global nitrogen cycle. Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

  4. 75 FR 22723 - Stream Protection Rule; Environmental Impact Statement

    Science.gov (United States)

    2010-04-30

    ..., 784, 816, and 817 RIN 1029-AC63 Stream Protection Rule; Environmental Impact Statement AGENCY: Office... streams from the adverse impacts of surface coal mining operations. We are requesting comments for the... mining activities may be conducted in or near perennial or intermittent streams. That rule, which this...

  5. Effects of Concrete Channels on Stream Biogeochemistry, Maryland Coastal Plain

    Science.gov (United States)

    Prestegaard, K. L.; Gilbert, L.; Phemister, K.

    2005-05-01

    In the 1950's and 60's, extensive networks of cement-lined channels were built in suburban watersheds near Washington, D.C. to convey storm water to downstream locations. These cement-lined stream channels limit interactions between surface and groundwater and they provide sources of alkalinity in Maryland Coastal Plain watersheds that normally have low alkalinity. This project was designed to 1) compare base flow water chemistry in headwater reaches of urban and non-urban streams, and 2) to evaluate downstream changes in water chemistry in channelized urban streams in comparison with non-urban reference streams. During a drought year, headwater streams in both urban and non-urban sites had significant concentrations of Fe(II) that were discharged from groundwater sources and rapidly oxidized by iron-oxidizing bacteria. During a wet year, the concentrations of Fe(II) were higher in headwater urban streams than in the non-urban streams. This suggests that impervious surfaces in headwater urban watersheds prevent the recharge of oxygen-rich waters during storm events, which maintains iron-rich groundwater discharge to the stream. Downstream changes in water chemistry are prominent in cement-lined urban channels because they are associated with distinctive microbial communities. The headwater zones of channelized streams are dominated by iron-ozidizing bacteria, that are replaced downstream by manganese-oxidizing zones, and replaced further downstream by biofilms dominated by photosynthesizing cyanobacteria. The reaches dominated by cyanobacteria exhibit diurnal changes in pH due to uptake of CO2 for photosynthesis. Diurnal changes range from 7.5 to 8.8 in the summer months to 7.0 to 7.5 in the cooler months, indicating both the impact of photosynthesis and the additional source of alkalinity provided by concrete. The dissolved oxygen, pH, and other characteristics of tributaries dominated by cyanobacteria are similar to the water chemistry characteristics observed in

  6. Channel changes following headwater reforestation: The Ganaraska river, Ontario, Canada

    International Nuclear Information System (INIS)

    Buttle, J.M.

    1995-01-01

    Reforestation of headwater slopes of the Ganaraska River basin in southern Ontario following World War II has resulted in decreased peak flows and has likely reduced sediment yields. Changes in channel morphology produced by these modifications to the hydrologic regime were examined for a 6.7 km section of river in the context of Schumm's (1977) qualitative model of channel response to reforestation. Flood channel width (measured from air photographs) has decreased since 1928, while cross-sectional measurements during stream gauging in the study section revealed a decrease in the channel's width/depth ratio between 1960 and 1975. Both of these trends agree with Schumm's model. Changes in channel planform were dominated by downstream translation of meander bends and by meander cutoffs. The model predicted an increase in channel sinuosity in response to decreased peak flows and bed-material yield from the basin. However, sinuosity for the entire river section decreased significantly between 1928 and 1988, and only one reach experienced an increase in sinuosity following reforestation. A possible explanation for the model's failure to describe temporal changes in the Ganaraska's sinuosity involves a negative feedback whereby the increased sinuosity produced by decreased flow and sediment yield enhances potential for ice jams and meander cutoffs, which in turn reduce sinuosity. This limited test of Schumm's model suggests that caution be used when applying the model and its variants to reconstructions of basin palaeohydrology, and predictions of channel response to anthropogenic and natural changes to the hydrologic regime. 31 refs, 11 figs, 1 tab

  7. Intermittent Testicular Torsion

    African Journals Online (AJOL)

    2017-06-02

    Jun 2, 2017 ... had prior episodes of testicular pain, suggesting that they may have had intermittent torsion before .... None of the patients had antecedent history of sexual exposure, fever, or urinary tract infection .... torsion of the spermatic cord portends an increased risk of acute testicular infarction. J Urol 2008;180 4 ...

  8. In-stream Physical Heterogeneity, Rainfall Aided Flushing, and Discharge on Stream Water Quality.

    Science.gov (United States)

    Gomes, Pattiyage I A; Wai, Onyx W H

    2015-08-01

    Implications of instream physical heterogeneity, rainfall-aided flushing, and stream discharge on water quality control have been investigated in a headwater stream of a climatic region that has contrasting dry and wet seasons. Dry (low flow) season's physical heterogeneity showed a positive correlation with good water quality. However, in the wet season, physical heterogeneity showed minor or no significance on water quality variations. Furthermore, physical heterogeneity appeared to be more complementary with good water quality subsequent to rainfall events. In many cases stream discharge was a reason for poor water quality. For the dry season, graywater inputs to the stream could be held responsible. In the wet season, it was probably the result of catchment level disturbances (e.g., regulation of ephemeral freshwater paths). Overall, this study revealed the importance of catchment-based approaches on water quality improvement in tandem with in-stream approaches framed on a temporal scale.

  9. Assessing the ecological status of the Cisadane River’s headwaters using benthic macroinvertebrates

    Science.gov (United States)

    Krisanti, M.; Wardiatno, Y.; Anzani, Y. M.

    2017-01-01

    Benthic macroinvertebrates are commonly used in river health biomonitoring. In monitoring program biotic indices are now widely established in water quality monitoring around the world, including in the tropical countries. The aim of this study was to reveal the ecological status of Cisadane River’s headwaters in inside and outside of Mount Halimun-Salak National Park by using benthic macroinvertebrates. The research was conducted in the headwaters of Cisadane River located in Mount Halimun-Salak National Park. Macroinvertebrates were collected from four sites, i.e. inside the park (station 1, 2, 3, and 4) and from two sites outside the park (station 5 and 6). Collections were made twice a month, starting from April to June 2015 by means of Surber sampler (frame area 30x30 cm). A total of 65 genera from 38 families and 11 orders were found in the river. The results showed that based on diversity index, Lincoln Quality Index (LQI), Family Biotic Index (FBI), and Stream Invertebrate Grade Number Average Level 2 (SIGNAL 2), stations located within national park were ecologically better than those outside national park. Rivers with well-preserved riverside vegetation, as in the national park area have greater ecological status.

  10. Reactive solute transport in acidic streams

    Science.gov (United States)

    Broshears, R.E.

    1996-01-01

    Spatial and temporal profiles of Ph and concentrations of toxic metals in streams affected by acid mine drainage are the result of the interplay of physical and biogeochemical processes. This paper describes a reactive solute transport model that provides a physically and thermodynamically quantitative interpretation of these profiles. The model combines a transport module that includes advection-dispersion and transient storage with a geochemical speciation module based on MINTEQA2. Input to the model includes stream hydrologic properties derived from tracer-dilution experiments, headwater and lateral inflow concentrations analyzed in field samples, and a thermodynamic database. Simulations reproduced the general features of steady-state patterns of observed pH and concentrations of aluminum and sulfate in St. Kevin Gulch, an acid mine drainage stream near Leadville, Colorado. These patterns were altered temporarily by injection of sodium carbonate into the stream. A transient simulation reproduced the observed effects of the base injection.

  11. Radioactive Cs-137 discharge from Headwater Forested Catchment in Fukushima after Fukushima Dai-ichi Nuclear Power Plant Accident

    Science.gov (United States)

    Iwagami, S.; Onda, Y.; Tsujimura, M.; Sakakibara, K.; Konuma, R.

    2015-12-01

    Radiocesium migration from headwater forested catchment is important perception as output from the forest which is also input to the subsequent various land use and downstream rivers after Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident. In this study, Cs-137 concentration of dissolved water, suspended sediment and coarse organic matter such as leaf and branch were monitored. Discharge amount of stream water, suspended sediment and coarse organic matter were measured to investigate the discharge amount of radiocesium and composition of radiocesium discharge form through the headwater stream. Observation were conducted at stream site in four headwater catchments in Yamakiya district, located ~35 km north west of FDNPP from June 2011 (suspended sediment and coarse organic matter: August 2012) to December 2014.The Cs-137 concentration of dissolved water was around 1Bq/l at June 2011. Then declined to 0.1 Bq/l at December 2011. And in December 2014, it declined to 0.01 Bq/l order. Declining trend of Cs-137 concentration in dissolved water was expressed in double exponential model. Also temporary increase was observed in dissolved Cs-137 during the rainfall event. The Cs-137 concentration of suspended sediment and coarse organic matter were 170-49000 Bq/kg and 350-14000 Bq/kg respectably. The Cs-137 concentration of suspended sediment showed good correlation with average deposition density of catchment. The effect of decontamination works appeared in declining of Cs-137 concentration in suspended sediment. Contribution rate of Cs-137 discharge by suspended sediment was 96-99% during a year. Total annual Cs-137 discharge from the catchment were 0.02-0.3% of the deposition.

  12. Streams with Strahler Stream Order

    Data.gov (United States)

    Minnesota Department of Natural Resources — Stream segments with Strahler stream order values assigned. As of 01/08/08 the linework is from the DNR24K stream coverages and will not match the updated...

  13. Quasistatic Dynamics with Intermittency

    International Nuclear Information System (INIS)

    Leppänen, Juho; Stenlund, Mikko

    2016-01-01

    We study an intermittent quasistatic dynamical system composed of nonuniformly hyperbolic Pomeau–Manneville maps with time-dependent parameters. We prove an ergodic theorem which shows almost sure convergence of time averages in a certain parameter range, and identify the unique physical family of measures. The theorem also shows convergence in probability in a larger parameter range. In the process, we establish other results that will be useful for further analysis of the statistical properties of the model.

  14. Quasistatic Dynamics with Intermittency

    Energy Technology Data Exchange (ETDEWEB)

    Leppänen, Juho; Stenlund, Mikko, E-mail: mikko.stenlund@helsinki.fi [University of Helsinki, Department of Mathematics and Statistics (Finland)

    2016-06-15

    We study an intermittent quasistatic dynamical system composed of nonuniformly hyperbolic Pomeau–Manneville maps with time-dependent parameters. We prove an ergodic theorem which shows almost sure convergence of time averages in a certain parameter range, and identify the unique physical family of measures. The theorem also shows convergence in probability in a larger parameter range. In the process, we establish other results that will be useful for further analysis of the statistical properties of the model.

  15. Use of multiple dispersal pathways facilitates amphibian persistence in stream networks

    Science.gov (United States)

    Campbell, Grant E.H.; Nichols, J.D.; Lowe, W.H.; Fagan, W.F.

    2010-01-01

    Although populations of amphibians are declining worldwide, there is no evidence that salamanders occupying small streams are experiencing enigmatic declines, and populations of these species seem stable. Theory predicts that dispersal through multiple pathways can stabilize populations, preventing extinction in habitat networks. However, empirical data to support this prediction are absent for most species, especially those at risk of decline. Our mark-recapture study of stream salamanders reveals both a strong upstream bias in dispersal and a surprisingly high rate of overland dispersal to adjacent headwater streams. This evidence of route-dependent variation in dispersal rates suggests a spatial mechanism for population stability in headwater-stream salamanders. Our results link the movement behavior of stream salamanders to network topology, and they underscore the importance of identifying and protecting critical dispersal pathways when addressing region-wide population declines.

  16. Use of multiple dispersal pathways facilitates amphibian persistence in stream networks.

    Science.gov (United States)

    Campbell Grant, Evan H; Nichols, James D; Lowe, Winsor H; Fagan, William F

    2010-04-13

    Although populations of amphibians are declining worldwide, there is no evidence that salamanders occupying small streams are experiencing enigmatic declines, and populations of these species seem stable. Theory predicts that dispersal through multiple pathways can stabilize populations, preventing extinction in habitat networks. However, empirical data to support this prediction are absent for most species, especially those at risk of decline. Our mark-recapture study of stream salamanders reveals both a strong upstream bias in dispersal and a surprisingly high rate of overland dispersal to adjacent headwater streams. This evidence of route-dependent variation in dispersal rates suggests a spatial mechanism for population stability in headwater-stream salamanders. Our results link the movement behavior of stream salamanders to network topology, and they underscore the importance of identifying and protecting critical dispersal pathways when addressing region-wide population declines.

  17. Towards Mapping the Provision of Ecosystem Services from Headwater Wetlands in the Susquehanna River Basin

    Science.gov (United States)

    Headwater wetlands provide a range of ecosystem services including habitat provisioning and flood retention. Following the River Ecosystem Synthesis framework we identified and assessed not only headwater wetlands, but unconstrained reaches with the potential to support diverse s...

  18. Intermittency in nuclear multifragmentation

    International Nuclear Information System (INIS)

    Ploszajczak, M.; Tucholski, A.

    1990-07-01

    Fluctuations of the fragment size distribution in a percolation model and in nuclear multifragmentation following the breakup of high energy nuclei in the nuclear emulsion are studied using the method of scaled factorial moments. An intermittent patern of fluctuations is found in the data as well as in the percolation lattice calculation. This is a consequence of both a self-similarity in the fragment size distribution and a random character for the scaling law. These fluctuations are in general well-described by percolation model. The multifractal dimensions are calculated and their relevance to the study of possible critical behaviour is pointed out. (orig.)

  19. Multidimensional intermittency in hadronic collisions

    International Nuclear Information System (INIS)

    Pan, J.; Hwa, R.C.

    1992-06-01

    The study of intermittency in high-energy hadronic collisions by the Monte Carlo code ECCO is extended to 3-dimensional phase space. Strong intermittency is found in agreement with the data. Fluctuation in the impact parameter is responsible for the intermittency in lnp T , and the transverse-momentum conservation leads to negative intermittency slopes in the azimuthal angle φ. The Ochs-Wosiek plots are linear in all dimensions having universal slopes. An exponent ν = 1.448 emerges to characterize multiparticle production in pp collisions. The properties of G moments are also examined, and the fractal dimensions determined

  20. 78 FR 42030 - Reservoirs at Headwaters of the Mississippi River; Use and Administration

    Science.gov (United States)

    2013-07-15

    ... Headwaters of the Mississippi River; Use and Administration AGENCY: U.S. Army Corps of Engineers, DoD. ACTION... proposing to amend the rules regarding use and administration of the reservoirs at the headwaters of the... Headwaters reservoirs containing minimum flow values that differ from those currently codified in the Code of...

  1. Spatial patterns of soil nitrification and nitrate export from forested headwaters in the northeastern United States

    Science.gov (United States)

    Ross, D.S.; Shanley, J.B.; Campbell, J.L.; Lawrence, G.B.; Bailey, S.W.; Likens, G.E.; Wemple, B.C.; Fredriksen, G.; Jamison, A.E.

    2012-01-01

    Nitrogen export from small forested watersheds is known to be affected by N deposition but with high regional variability. We studied 10 headwater catchments in the northeastern United States across a gradient of N deposition (5.4 - 9.4 kg ha -1 yr -1) to determine if soil nitrification rates could explain differences in stream water NO 3 - export. Average annual export of two years (October 2002 through September 2004) varied from 0.1 kg NO 3 --N ha -1 yr -1 at Cone Pond watershed in New Hampshire to 5.1 kg ha -1 yr -1 at Buck Creek South in the western Adirondack Mountains of New York. Potential net nitrification rates and relative nitrification (fraction of inorganic N as NO 3 -) were measured in Oa or A soil horizons at 21-130 sampling points throughout each watershed. Stream NO 3 - export was positively related to nitrification rates (r 2 = 0.34, p = 0.04) and the relative nitrification (r 2 = 0.37, p = 0.04). These relationships were much improved by restricting consideration to the 6 watersheds with a higher number of rate measurements (59-130) taken in transects parallel to the streams (r 2 of 0.84 and 0.70 for the nitrification rate and relative nitrification, respectively). Potential nitrification rates were also a better predictor of NO 3 - export when data were limited to either the 6 sampling points closest to the watershed outlet (r 2 = 0.75) or sampling points <250 m from the watershed outlet (r 2 = 0.68). The basal area of conifer species at the sampling plots was negatively related to NO 3 - export. These spatial relationships found here suggest a strong influence of near-stream and near-watershed-outlet soils on measured stream NO 3 - export. Copyright 2012 by the American Geophysical Union.

  2. Stream Crossings

    Data.gov (United States)

    Vermont Center for Geographic Information — Physical measurements and attributes of stream crossing structures and adjacent stream reaches which are used to provide a relative rating of aquatic organism...

  3. Akamai Streaming

    OpenAIRE

    ECT Team, Purdue

    2007-01-01

    Akamai offers world-class streaming media services that enable Internet content providers and enterprises to succeed in today's Web-centric marketplace. They deliver live event Webcasts (complete with video production, encoding, and signal acquisition services), streaming media on demand, 24/7 Webcasts and a variety of streaming application services based upon their EdgeAdvantage.

  4. Watershed Urbanization Linked to Differences in Stream Bacterial Community Composition

    Directory of Open Access Journals (Sweden)

    Jacob D. Hosen

    2017-08-01

    Full Text Available Urbanization strongly influences headwater stream chemistry and hydrology, but little is known about how these conditions impact bacterial community composition. We predicted that urbanization would impact bacterial community composition, but that stream water column bacterial communities would be most strongly linked to urbanization at a watershed-scale, as measured by impervious cover, while sediment bacterial communities would correlate with environmental conditions at the scale of stream reaches. To test this hypothesis, we determined bacterial community composition in the water column and sediment of headwater streams located across a gradient of watershed impervious cover using high-throughput 16S rRNA gene amplicon sequencing. Alpha diversity metrics did not show a strong response to catchment urbanization, but beta diversity was significantly related to watershed impervious cover with significant differences also found between water column and sediment samples. Samples grouped primarily according to habitat—water column vs. sediment—with a significant response to watershed impervious cover nested within each habitat type. Compositional shifts for communities in urbanized streams indicated an increase in taxa associated with human activity including bacteria from the genus Polynucleobacter, which is widespread, but has been associated with eutrophic conditions in larger water bodies. Another indicator of communities in urbanized streams was an OTU from the genus Gallionella, which is linked to corrosion of water distribution systems. To identify changes in bacterial community interactions, bacterial co-occurrence networks were generated from urban and forested samples. The urbanized co-occurrence network was much smaller and had fewer co-occurrence events per taxon than forested equivalents, indicating a loss of keystone taxa with urbanization. Our results suggest that urbanization has significant impacts on the community composition

  5. Metabolic Effects of Intermittent Fasting.

    Science.gov (United States)

    Patterson, Ruth E; Sears, Dorothy D

    2017-08-21

    The objective of this review is to provide an overview of intermittent fasting regimens, summarize the evidence on the health benefits of intermittent fasting, and discuss physiological mechanisms by which intermittent fasting might lead to improved health outcomes. A MEDLINE search was performed using PubMed and the terms "intermittent fasting," "fasting," "time-restricted feeding," and "food timing." Modified fasting regimens appear to promote weight loss and may improve metabolic health. Several lines of evidence also support the hypothesis that eating patterns that reduce or eliminate nighttime eating and prolong nightly fasting intervals may result in sustained improvements in human health. Intermittent fasting regimens are hypothesized to influence metabolic regulation via effects on (a) circadian biology, (b) the gut microbiome, and (c) modifiable lifestyle behaviors, such as sleep. If proven to be efficacious, these eating regimens offer promising nonpharmacological approaches to improving health at the population level, with multiple public health benefits.

  6. Global Positioning System (GPS) and Geographic Information System (GIS) analysis of mobile harvesting equipment and sediment delivery to streams during forest harvest operations on steep terrain: Experimental design

    Science.gov (United States)

    Daniel Bowker; Jeff Stringer; Chris Barton; Songlin Fei

    2011-01-01

    Sediment mobilized by forest harvest machine traffic contributes substantially to the degradation of headwater stream systems. This study monitored forest harvest machine traffic to analyze how it affects sediment delivery to stream channels. Harvest machines were outfitted with global positioning system (GPS) dataloggers, recording machine movements and working status...

  7. Ecosystem and physiological scales of microbial responses to nutrients in a detritus-based stream: results of a 5-year continuous enrichment

    Science.gov (United States)

    Keller Suberkropp; Vladislav Gulis; Amy D. Rosemond; Jonathan Benstead

    2010-01-01

    Our study examined the response of leaf detritus–associated microorganisms (both bacteria and fungi) to a 5-yr continuous nutrient enrichment of a forested headwater stream. Leaf litter dominates detritus inputs to such streams and, on a system wide scale, serves as the key substrate for microbial colonization. We determined physiological responses as microbial biomass...

  8. Assessment of corn and banana leaves as potential standardized substrates for leaf decomposition in streams affected by mountaintop removal coal mining, West Virginia, USA

    Science.gov (United States)

    Mountaintop removal and valley filling is a method of coal mining that buries Central Appalachian headwater streams. A 2007 federal court ruling highlighted the need for measurement of both ecosystem structure and function when assessing streams for mitigaton. Rapid functional as...

  9. Barriers, invasion, and conservation of native salmonids in coldwater streams [Box 18.2

    Science.gov (United States)

    Bruce Rieman; Michael Young; Kurt Fausch; Jason Dunham; Douglas Peterson

    2010-01-01

    Habitat loss and fragmentation are threats to persistence of many native fish populations. Invading nonnative species that may restrict or displace native species are also important. These two issues are particularly relevant for native salmonids that are often limited to remnant habitats in cold, headwater streams. On the surface, reversing threats to native fishes...

  10. Leaf litter decomposition and elemental change in three Appalachian mountain streams of different pH

    Science.gov (United States)

    Steven W. Solada; Sue A. Perry; William B. Perry

    1996-01-01

    The decomposition of leaf litter provides the primary nutrient source for many of the headwater mountain streams in forested catchments. An investigation of factors affected by global change that influence organic matter decomposition, such as temperature and pH, is important in understanding the dynamics of these systems. We conducted a study of leaf litter elemental...

  11. Fate in intermittent claudication

    DEFF Research Database (Denmark)

    Jelnes, Rolf; Gaardsting, O; Hougaard Jensen, K

    1986-01-01

    , or an ankle/arm pressure index below 50% were individually significantly associated with progression of the arteriosclerotic disease. These findings show the importance of peripheral blood pressure measurements in the management of patients with intermittent claudication due to arteriosclerotic disease........ The rate of clinical progression of the arteriosclerotic disease (that is, rest pain or gangrene) of the worst affected leg was 7.5% in the first year after referral. Thereafter the rate was 2.2% a year. An ankle systolic blood pressure below 70 mm Hg, a toe systolic blood pressure below 40 mm Hg...... 113 of the patients (44%) had died. Causes of death were no different from those in the general population. Mortality was twice that of the general population matched for age and sex. Mortality among the men was twice that among the women. In men under 60 mortality was four times that expected...

  12. Effects of urban stream burial on nitrogen uptake and ...

    Science.gov (United States)

    Urbanization has resulted in extensive burial and channelization of headwater streams, yet little is known about impacts on stream ecosystem functions critical for reducing downstream nitrogen pollution. To characterize the biogeochemical impact of stream burial, we measured NO3- uptake, using 15N-NO3- isotope tracer releases, and whole stream metabolism, during four seasons in three paired buried and open streams reaches within the Baltimore Ecosystem Study Long-term Ecological Research Network. Stream burial increased NO3- uptake lengths, by a factor of 7.5 (p < 0.01) and decreased nitrate uptake velocity and areal nitrate uptake rate by factors of 8.2 (p = 0.01) and 9.6 (p < 0.001), respectively. Stream burial decreased gross primary productivity by a factor of 9.2 (p < 0.05) and decreased ecosystem respiration by a factor of 4.2 (p = 0.06). From statistical analysis of Excitation Emissions Matrices (EEMs), buried streams were also found to have significantly less labile dissolved organic matter. Furthermore, buried streams had significantly lower transient storage and water temperatures. Overall, differences in NO3- uptake and metabolism were primarily explained by decreased transient storage and light availability in buried streams. We estimate that stream burial increases daily watershed nitrate export by as much as 500% due to decreased in-stream retention and may considerably decrease carbon export via decreased primary production. These results

  13. Mapping of hydropedologic spatial patterns in a steep headwater catchment

    Science.gov (United States)

    Cody P. Gillin; Scott W. Bailey; Kevin J. McGuire; John P. Gannon

    2015-01-01

    A hydropedologic approach can be used to describe soil units affected by distinct hydrologic regimes. We used field observations of soil morphology and geospatial information technology to map the distribution of five hydropedologic soil units across a 42-ha forested headwater catchment. Soils were described and characterized at 172 locations within Watershed 3, the...

  14. Importance of terrestrial arthropods as subsidies in lowland Neotropical rain forest stream ecosystems

    Science.gov (United States)

    Small, Gaston E.; Torres, Pedro J.; Schwizer, Lauren M.; Duff, John H.; Pringle, Catherine M.

    2013-01-01

    The importance of terrestrial arthropods has been documented in temperate stream ecosystems, but little is known about the magnitude of these inputs in tropical streams. Terrestrial arthropods falling from the canopy of tropical forests may be an important subsidy to tropical stream food webs and could also represent an important flux of nitrogen (N) and phosphorus (P) in nutrient-poor headwater streams. We quantified input rates of terrestrial insects in eight streams draining lowland tropical wet forest in Costa Rica. In two focal headwater streams, we also measured capture efficiency by the fish assemblage and quantified terrestrially derived N- and P-excretion relative to stream nutrient uptake rates. Average input rates of terrestrial insects ranged from 5 to 41 mg dry mass/m2/d, exceeding previous measurements of aquatic invertebrate secondary production in these study streams, and were relatively consistent year-round, in contrast to values reported in temperate streams. Terrestrial insects accounted for half of the diet of the dominant fish species, Priapicthys annectens. Although terrestrially derived fish excretion was found to be a small flux relative to measured nutrient uptake rates in the focal streams, the efficient capture and processing of terrestrial arthropods by fish made these nutrients available to the local stream ecosystem. This aquatic-terrestrial linkage is likely being decoupled by deforestation in many tropical regions, with largely unknown but potentially important ecological consequences.

  15. Extent of Stream Burial and Relationships to Watershed Area, Topography, and Impervious Surface Area

    Directory of Open Access Journals (Sweden)

    Roy E. Weitzell

    2016-11-01

    Full Text Available Stream burial—the routing of streams through culverts, pipes, and concrete lined channels, or simply paving them over—is common during urbanization, and disproportionately affects small, headwater streams. Burial undermines the physical and chemical processes governing life in streams, with consequences for water quality and quantity that may amplify from headwaters to downstream receiving waters. Knowledge of the extent of stream burial is critical for understanding cumulative impacts to stream networks, and for future decision-making allowing for urban development while protecting ecosystem function. We predicted stream burial across the urbanizing Potomac River Basin (USA for each 10-m stream segment in the basin from medium-resolution impervious cover data and training observations obtained from high-resolution aerial photography in a GIS. Results were analyzed across a range in spatial aggregation, including counties and independent cities, small watersheds, and regular spatial grids. Stream burial was generally correlated with total impervious surface area (ISA, with areas exhibiting ISA above 30% often subject to elevated ratios of stream burial. Recurring patterns in burial predictions related to catchment area and topographic slope were also detected. We discuss these results in the context of physiographic constraints on stream location and urban development, including implications for environmental management of aquatic resources.

  16. Benthic invertebrates in the headwaters of the Wye and Severn: effects of forestry and clear-felling

    Science.gov (United States)

    Gee, J. H. R.; Smith, B. D.

    Invertebrate communities were recorded in three surveys between 1974 and 1994 of headwaters of the Wye and Severn at Plynlimon: the Afon Gwy (unforested), the Afon Hore (initially forested) and the Afon Hafren (forested throughout). The data cover periods before and after the clear-felling of a large area of coniferous forest in the catchment of the Hore. All three streams contained invertebrates characteristic of acidic, upland conditions and had similar species richness. Differences in assemblage composition within streams between surveys could be related to differences in method or timing of sampling. All assemblages were dominated by Insecta, particularly Plecoptera and Diptera, whereas Ephemeroptera, Moilusca, Crustacca and some families of Trichoptera (notably Hydropsychidae and Philopotamidae) were poorly represented. The forested streams (Hafren and Hore) contained similar assemblages which differed from those in the unforested stream (Gwy) in containing lower densities of Ephemeroptera and Oligochacta and much higher densities of nemourid and leuctrid Plecoptera. Clear-felling of the Hore catchment resulted in changes in physical and chemical conditions (including a reduction of stream pH, and increases in dissolved aluminium concentration and summer water temperature) but no related change in the invertebrate assemblage. The apparent failure of invertebrates to respond as expected to substantial changes in local environmental conditions may reflect either a lack of understanding of causal links between invertebrates and environmental factors, or the over-riding influence of the dynamics of recruitment to populations.

  17. The role of groundwater in streamflow in a headwater catchment with sub-humid climate

    Science.gov (United States)

    Liu, Yaping; Tian, Fuqiang; Hu, Hongchang; Tie, Qiang

    2015-04-01

    Recent studies have suggested that bedrock groundwater can exert considerable influence on streamflow in headwater catchments under humid climate. However, study of the role of bedrock groundwater is still challenged due to limited direct observation data. In this study, by utilizing observed hydrometric and hydrochemical data, we aimed at characterize the bedrock groundwater's response to rainfall at hillslope and catchment scales in a small headwater catchment with sub-humid climate. We selected Xitaizi catchment with area of 6.7 km in the earth-rock mountain region, which located in the north of Beijing, China, as study area. The catchment bedrock is mainly consist of fractured granite. Four weather stations were installed to observe the weather condition and soil volumetric water content (VWC) at depth of 10-60 cm with 10-minute interval. Five wells with depth of 10 m were drilled in two slopes to monitor the bedrock water table by pneumatic water gauge. At slope 1, the soil VWC at depth of 10-80 cm were also observed by soil moisture sensors, and surface/subsurface hillslope runoff at three different layers (0-20cm, 20-80cm, 80-300cm) was observed by three recording buckets. Field works were conducted from July 2013 to November 2014. During the period, precipitation, river, spring and groundwater were sampled nearly monthly. Water temperature, electrical conductivity (EC) and pH were measured in site with portable instruments. In addition, the precipitation, river and groundwater were also sampled intensively during two storm events. All the samples were subjected to stable isotope analysis, the samples taken monthly during the period from July 2013 to July 2014 were subjected to hydrochemistry analysis. Our results show that: (1) the bedrock groundwater is the dominant component of streamflow in the headwater catchment with sub-humid climate; (2) stream is recharged by groundwater sourcing from different mountains with different hydrochemistry characteristics

  18. Lessons in collaboration and effective field research from the Appalachian Headwaters Research Experience for Undergraduates Program

    Science.gov (United States)

    Jones, A. L.; Fox, J.; Wilder, M. S.

    2009-12-01

    In the summer of 2009, the authors launched year one of a three-year National Science Foundation-funded Research Experience for Undergraduates entitled "Carbon Storage and Headwater Health in the Appalachian Headwaters." Eight undergraduates selected from a nationally competitive field of more than 60 applicants participated in the ten-week field- and laboratory-based program along with three middle- and high-school teachers. Each student developed and completed an independent research project related to coal mining’s impact on soil organic carbon and sediment transport processes. Specifically, they used isotope ratio mass spectrometry to measure the carbon and nitrogen stable isotopic signature of soils and sediments in the Appalachian headwater landscapes and first order streams of Kentucky's southeastern coalfields. Among the program's innovative features was its fundamentally collaborative nature--which was represented in several ways. First, the background of the three program leaders was very different: an environmental planner with an academic background in land use planning and administration (Jones); a civil engineer trained in biogeochemistry and watershed modeling (Fox); and an environmental educator experienced in both formal and nonformal educator training and certification (Wilder). The program was also a collaboration between a Carnegie 1 research-oriented institution and an undergraduate/ teaching -focused regional comprehensive university. Finally, the participants themselves represented a diversity of disciplines and institutional backgrounds--including biology, geology, chemistry, environmental science and civil engineering. The Research Experience for Teachers component was another innovative program element. The teachers participated in all field and laboratory research activities during the first six weeks, then developed a unit of study for their own classrooms to be implemented during the current school year. In addition to the six

  19. Assessment of climate change impacts on streamflow dynamics in the headwaters of the Amazon River basin

    Science.gov (United States)

    Yoon, Y.; Beighley, E.

    2015-12-01

    The Amazon River basin is the largest watershed in the world containing thousands of tributaries. Although the mainstream and its larger tributaries have been the focus on much research, there has been few studies focused on the hydrodynamics of smaller rivers in the foothills of the Andes Mountains. These smaller rivers are of particular importance for the fishery industry because fish migrate up these headwater rivers to spawn. During the rainy season, fish wait for storm event to increase water depths to a sufficient level for their passage. Understanding how streamflow dynamics will change in response to future conditions is vital for the sustainable management of the fishery industry. In this paper, we focus on improving the accuracy of river discharge estimates on relatively small-scale sub-catchments (100 ~ 40,000 km2) in the headwaters of the Amazon River basin. The Hillslope River Routing (HRR) hydrologic model and remotely sensed datasets are used. We provide annual runoff, seasonal patterns, and daily discharge characteristics for 81 known migration reaches. The model is calibrated for the period 2000-2014 and climate forecasts for the period 2070-2100 are used to assess future changes in streamflow dynamics. The forecasts for the 2070 to 2100 period were obtained by selecting 5 climate models from IPCC's Fifth Assessment Report (AR5) Coupled Model Intercomparison Project Phase 5 (CMIP5) based on their ability to represent the main aspects of recent (1970 to 2000) Amazon climate. The river network for the HRR model is developing using surface topography based on the SRTM digital elevation model. Key model forcings include precipitation (TRMM 3B42) and evapotranspiration (MODIS ET, MOD16). Model parameters for soil depth, hydraulic conductivity, runoff coefficients and lateral routing were initially approximated based on literature values and adjusted during calibration. Measurements from stream gauges located near the reaches of interest were used for

  20. Seasonal Accumulation and Depletion of Local Sediment Stores of Four Headwater Catchments

    Directory of Open Access Journals (Sweden)

    Sarah E. Martin

    2014-07-01

    Full Text Available Seasonal turbidity patterns and event-level hysteresis analysis of turbidity verses discharge in four 1 km2 headwater catchments in California’s Sierra Nevada indicate localized in-channel sediment sources and seasonal accumulation-depletion patterns of stream sediments. Turbidity signals were analyzed for three years in order to look at the relationships between seasonal turbidity trends, event turbidity patterns, and precipitation type to stream sediment production and transport. Seasonal patterns showed more turbidity events associated with fall and early to mid- winter events than with peak snow-melt. No significant turbidity patterns emerged for periods of snow melt vs. rain. Single event hysteresis loops showed clockwise patterns were dominant suggesting local sediment sources. In successive discharge events, the largest turbidity spike was often associated with the first but not necessarily the largest discharge event-indicating seasonal depletion of local sediment stores. In multi-peaked discharge events, hysteresis loops shifted from clockwise to linear or random patterns suggesting that localized sediment stores are being used up and sufficient flow energy must be reached to start entraining the more consolidated bank/bed sediment or that dominant sediment sources may be shifting to less localized areas such as hill slopes. A conceptual model with phases of accumulation and transport is proposed.

  1. Naftidrofuryl for intermittent claudication.

    Science.gov (United States)

    De Backer, T L M; Vander Stichele, R; Lehert, P; Van Bortel, L

    2008-04-16

    Lifestyle changes and cardiovascular prevention measures are a primary treatment for intermittent claudication (IC). Symptomatic treatment with vasoactive agents (Anatomic Therapeutic Chemical Classification (ATC) for medicines from the World Health Organisation class CO4A) is controversial. To evaluate evidence on the efficacy and safety of oral naftidrofuryl (ATC CO4 21) versus placebo on the pain-free walking distance (PFWD) of people with IC by using a meta-analysis based on individual patient data (IPD). The Cochrane Peripheral Vascular Diseases Group searched their Trials Register (last searched December 2007) and CENTRAL (last searched 2007, Issue 4). We searched MEDLINE, EMBASE, International Pharmaceutical Abstracts, the Science Citation Index and contacted the authors and checked the reference lists of retrieved articles. We asked the manufacturing company for IPD. We included only randomized controlled trials (RCTs) with low or moderate risk of bias for which the IPD were available. We collected data from the electronic data file or from the case report form and checked the data by a statistical quality control procedure. All randomized patients were analyzed following the intention-to-treat (ITT) principle. The geometric mean of the relative improvement in PFWD was calculated for both treatment groups in all identified studies. The effect of the drug was assessed compared with placebo on final walking distance (WDf) using multilevel and random-effect models and adjusting for baseline walking distance (WD0). For the responder analysis, therapeutic success was defined as an improvement of walking distance of at least 50%. We included seven studies in the IPD (n = 1266 patients). One of these studies (n = 183) was only used in the sensitivity analysis so that the main analysis included 1083 patients. The ratio of the relative improvement in PFWD (naftidrofuryl compared with placebo) was 1.37 (95% confidence interval (CI) 1.32 to 1.51, P < 0.001). The

  2. Intermedia and Intermittency

    Directory of Open Access Journals (Sweden)

    Veres Bálint

    2014-12-01

    Full Text Available It is commonly known that medial reflections have been initiated by attempts to secure the borders of discrete medial forms and to define the modus operandi of each essentialized medial area. Later on, the focus of study has shifted to plurimedial formations and the interactions between predefined medial genres. In the last few decades, taxonomic approaches to various multi-, inter-, and transmedial phenomena dominated the discussions, which offered invaluable support in mapping the terrain, but at the same time hindered the analysis of the ephemeral, time-dependent aspects of plurimedial operations. While we explore the properties of each medial configuration, we lose sight of the actual historical drivers that produce ever-new configurations. My thesis is that any discourse on intermediality should be paralleled by a discourse on cultural intermittency, and consequently, media studies should involve an approach that focuses on the “ecosystem” of the constantly renewing media configurations from the point of view of their vitalizing potential and capability to trigger heightened experiences. This approach draws much inspiration from K. Ludwig Pfeiffer’s media anthropology that gives orientation in my paper.

  3. Chronic Intermittent Hypoxia Induces Atherosclerosis

    OpenAIRE

    Savransky, Vladimir; Nanayakkara, Ashika; Li, Jianguo; Bevans, Shannon; Smith, Philip L.; Rodriguez, Annabelle; Polotsky, Vsevolod Y.

    2007-01-01

    Rationale: Obstructive sleep apnea, a condition leading to chronic intermittent hypoxia (CIH), is associated with hyperlipidemia, atherosclerosis, and a high cardiovascular risk. A causal link between obstructive sleep apnea and atherosclerosis has not been established.

  4. Stream invertebrate productivity linked to forest subsidies: 37 stream-years of reference and experimental data.

    Science.gov (United States)

    Wallace, J Bruce; Eggert, Susan L; Meyer, Judy L; Webster, Jackson R

    2015-05-01

    Riparian habitats provide detrital subsidies of varying quantities and qualities to recipient ecosystems. We used long-term data from three reference streams (covering 24 stream-years) and 13-year whole-stream organic matter manipulations to investigate the influence of terrestrial detrital quantity and quality on benthic invertebrate community structure, abundance, biomass, and secondary production in rockface (RF) and mixed substrates (MS) of forested headwater streams. Using a mesh canopy covering the entire treatment stream, we examined effects of litter ex'clusion, small- and large-wood removal, and addition of artificial wood (PVC) and leaves of varying quality on organic matter standing crops and invertebrate community structure and function. We assessed differences in functional feeding group distribution between substrate types as influenced by organic matter manipulations and long-term patterns of predator and prey production in manipulated vs. reference years. Particulate organic matter standing crops in MS of the treatment stream declined drastically with each successive year of litter exclusion, approaching zero after three years. Monthly invertebrate biomass and annual secondary production was positively related to benthic organic matter in the MS habitats. Rockface habitats exhibited fewer changes than MS habitats across all organic matter manipulations. With leaf addition, the patterns of functional group distribution among MS and RF habitats returned to patterns seen in reference streams. Secondary production per unit organic matter standing crop was greatest for the leaf addition period, followed by the reference streams, and significantly less for the litter exclusion and wood removal periods. These data indicate that the limited organic matter remaining in the stream following litter exclusion and wood removal was more refractory than that in the reference streams, whereas the added leaf material was more labile and readily converted into

  5. Dynamic characterizers of spatiotemporal intermittency

    OpenAIRE

    Gupte, Neelima; Jabeen, Zahera

    2006-01-01

    Systems of coupled sine circle maps show regimes of spatiotemporally intermittent behaviour with associated scaling exponents which belong to the DP class, as well as regimes of spatially intermittent behaviour (with associated regular dynamical behaviour) which do not belong to the DP class. Both types of behaviour are seen along the bifurcation boundaries of the synchronized solutions, and contribute distinct signatures to the dynamical characterizers of the system, viz. the distribution of...

  6. Stream systems.

    Science.gov (United States)

    Jack E. Williams; Gordon H. Reeves

    2006-01-01

    Restored, high-quality streams provide innumerable benefits to society. In the Pacific Northwest, high-quality stream habitat often is associated with an abundance of salmonid fishes such as chinook salmon (Oncorhynchus tshawytscha), coho salmon (O. kisutch), and steelhead (O. mykiss). Many other native...

  7. Hydrologic response to valley-scale structure in alpine headwaters

    Science.gov (United States)

    Weekes, Anne A.; Torgersen, Christian E.; Montgomery, David R.; Woodward, Andrea; Bolton, Susan M.

    2015-01-01

    Few systematic studies of valley-scale geomorphic drivers of streamflow regimes in complex alpine headwaters have compared response between catchments. As a result, little guidance is available for regional-scale hydrological research and monitoring efforts that include assessments of ecosystem function. Physical parameters such as slope, elevation range, drainage area and bedrock geology are often used to stratify differences in streamflow response between sampling sites within an ecoregion. However, these metrics do not take into account geomorphic controls on streamflow specific to glaciated mountain headwaters. The coarse-grained nature of depositional features in alpine catchments suggests that these landforms have little water storage capacity because hillslope runoff moves rapidly just beneath the rock mantle before emerging in fluvial networks. However, recent studies show that a range of depositional features, including talus slopes, protalus ramparts and 'rock-ice' features may have more storage capacity than previously thought.

  8. Instream wood in a steep headwater channel: geomorphic significance of large and small wood

    Science.gov (United States)

    Galia, Tomáš; Šilhán, Karel; Ruiz-Villanueva, Virginia; Tichavský, Radek

    2016-04-01

    Besides the well-known significance of large wood (LW), also small woody pieces (SW; here defined as pieces with dimensions at least 0.5 m length and 0.05 m diameter), can play an important role in steep narrow headwaters. We inventoried instream wood in the 0.4 km long Mazák headwater channel, Moravskoslezské Beskydy Mts, Czech Republic (2pieces were European beeches (Fagus sylvatica L.); only two pieces were Norway spruces (Picea abies (L.) Karst.). First results showed an increase in the number of LWs in channel-reaches confined by the steepest adjacent hillslopes (especially at 0.15-0.20 km). Increasing downstream amount of SW most likely reflected transport processes in the stream, and the later deposition of SWs on the lowest channel gradients. Also LWs and SWs in the downstream channel-reaches were more decayed than wood presented in the upper reaches. The orientation of instream wood was connected with its length and stability, and LWs longer than 5 m were usually attached to adjacent hillslopes. Pieces longer than 2 m, which were unattached or were somehow stabilized in the channel bed, had often orientation of 0° or 337°. LWs were mostly unattached in the upstream channel-reaches, while often stabilized by adjacent hillslopes in the middle part. At 0.05-0.10 km, there were also many logs stabilized by bed sediments. By contrast, SWs were mostly unattached in the whole longitudinal profile. We observed higher % of influenced channel width by SWs than LWs. Also, SWs were usually entirely located in the channel, which was significantly different when compared to LWs. Nine small steps (step height ~0.5 m) were created by instream wood; six of them were formed by SWs. Dendrogeomorphic cross dating supported the observed decay status for LW/SW within the longitudinal profile: at the lowest channel gradients with wider higher active channels, the potential for storage of instream wood increased. In these downstream reaches we observed older LW and SW, with

  9. Effects of acidic precipitation on leaf decomposition rates, microbial biomass, and leaf pack macroinvertebrates in six streams on the Allegheny plateau of West Virginia

    Science.gov (United States)

    Erik S. Engstrom; Sean K. Meegan; Sue A. Perry; William B. Perry

    1996-01-01

    We studied the effects of acidification on leaf litter decomposition in six headwater streams in the Monongahela National Forest. These streams differed in underlying geology and mean baseflow pH (3.99, 4.24, 6.13, 6.47, 6.59, and 7.52). We placed 10-gram leaf packs of white oak, red maple, and yellow poplar in each stream, and retrieved them after two days, two weeks...

  10. Intermittency in 197Au fragmentation

    International Nuclear Information System (INIS)

    Dabrowska, A.; Holynski, R.; Olszewski, A.; Szarska, M.; Wilczynska, B.; Wolter, W.; Wosiek, B.; Cherry, M.L.; Deines-Jones, P.; Jones, W.V.; Sengupta, K.; Wefel, B.

    1995-07-01

    The concept of factorial moments was applied to an analysis of the dynamical fluctuations in the charge distributions of the fragments emitted from gold nuclei with energies 10.6 and < 1.0 GeV/n interacting with emulsion nuclei. Clear evidence for intermittent fluctuations has been found in an analysis using all the particles released from the gold projectile, with a stronger effect observed below 1 GeV/n than at 10.6 GeV/n. For the full data sets, however, the intermittency effect was found to be very sensitive to the singly charged particles, and neglecting these particles strongly reduces the intermittency signal. When the analysis is restricted to the multiply charged fragments, an intermittency effect is revealed only for multifragmentation events, although one that is enhanced as compared to the analysis of all, singly and multiply charged, particles. The properties of the anomalous fractal dimensions suggest a sequential decay mechanism, rather than the existence of possible critical behaviour in the process of nuclear fragmentation. The likely influence of the charge conservation effects and the finite size of decaying systems on the observed intermittency signals was pointed out. (author). 37 refs, 9 figs, 5 tabs

  11. Interactions between stream fungi and bacteria associated with decomposing leaf litter at different levels of nutrient availability

    Science.gov (United States)

    Vladislav Gulis; Keller Suberkropp

    2003-01-01

    We examined the potential for interactions between aquatic hyphomycetes and bacteria isolated from leaves decaying in a headwater stream. In agar plate assays, culture filtrates of each of 28 aquatic hyphomycete isolates tested (5 species) inhibited bacterial growth (16 Gram-negative bacterial isolates belonging to 6 colony morphotypes were tested). Inhibition of...

  12. Rare Moss-Built Microterraces in a High-Altitude, Acid Mine Drainage-Polluted Stream (Cordillera Negra, Peru)

    NARCIS (Netherlands)

    Sevink, J.; Verstraten, J.M.; Kooijman, A.M.; Loayza-Muro, R.A.; Hoitinga, L.; Palomino, E.J.; Jansen, B.

    2015-01-01

    The Rio Santiago in the Cordillera Negra of Peru is severely contaminated by acid mine drainage in its headwaters. In a strongly acid stream, at about 3800 m above sea level (masl), microterraces were found with terrace walls built up of dead moss, with encrustations and interstitial fine, creamy

  13. Nutrient enrichment differentially affects body sizes of primary consumers and predators in a detritus-based stream

    Science.gov (United States)

    John M. Davis; Amy D. Rosemond; Sue L. Eggert; Wyatt F. Cross; J. Bruce. Wallace

    2010-01-01

    We assessed how a 5-yr nutrient enrichment affected the responses of different size classes of primary consumers and predators in a detritus-based headwater stream. We hypothesized that alterations in detritus availability because of enrichment would decrease the abundance and biomass of large-bodied consumers. In contrast, we found that 2 yr of enrichment increased...

  14. Stream Response to an Extreme Defoliation Event

    Science.gov (United States)

    Gold, A.; Loffredo, J.; Addy, K.; Bernhardt, E. S.; Berdanier, A. B.; Schroth, A. W.; Inamdar, S. P.; Bowden, W. B.

    2017-12-01

    Extreme climatic events are known to profoundly impact stream flow and stream fluxes. These events can also exert controls on insect outbreaks, which may create marked changes in stream characteristics. The invasive Gypsy Moth (Lymantria dispar dispar) experiences episodic infestations based on extreme climatic conditions within the northeastern U.S. In most years, gypsy moth populations are kept in check by diseases. In 2016 - after successive years of unusually warm, dry spring and summer weather -gypsy moth caterpillars defoliated over half of Rhode Island's 160,000 forested ha. No defoliation of this magnitude had occurred for more than 30 years. We examined one RI headwater stream's response to the defoliation event in 2016 compared with comparable data in 2014 and 2015. Stream temperature and flow was gauged continuously by USGS and dissolved oxygen (DO) was measured with a YSI EXO2 sonde every 30 minutes during a series of deployments in the spring, summer and fall from 2014-2016. We used the single station, open channel method to estimate stream metabolism metrics. We also assessed local climate and stream temperature data from 2009-2016. We observed changes in stream responses during the defoliation event that suggest changes in ET, solar radiation and heat flux. Although the summer of 2016 had more drought stress (PDSI) than previous years, stream flow occurred throughout the summer, in contrast to several years with lower drought stress when stream flow ceased. Air temperature in 2016 was similar to prior years, but stream temperature was substantially higher than the prior seven years, likely due to the loss of canopy shading. DO declined dramatically in 2016 compared to prior years - more than the rising stream temperatures would indicate. Gross Primary Productivity was significantly higher during the year of the defoliation, indicating more total fixation of inorganic carbon from photo-autotrophs. In 2016, Ecosystem Respiration was also higher and Net

  15. Stream Evaluation

    Data.gov (United States)

    Kansas Data Access and Support Center — Digital representation of the map accompanying the "Kansas stream and river fishery resource evaluation" (R.E. Moss and K. Brunson, 1981.U.S. Fish and Wildlife...

  16. A Statistical Method to Predict Flow Permanence in Dryland Streams from Time Series of Stream Temperature

    Directory of Open Access Journals (Sweden)

    Ivan Arismendi

    2017-12-01

    Full Text Available Intermittent and ephemeral streams represent more than half of the length of the global river network. Dryland freshwater ecosystems are especially vulnerable to changes in human-related water uses as well as shifts in terrestrial climates. Yet, the description and quantification of patterns of flow permanence in these systems is challenging mostly due to difficulties in instrumentation. Here, we took advantage of existing stream temperature datasets in dryland streams in the northwest Great Basin desert, USA, to extract critical information on climate-sensitive patterns of flow permanence. We used a signal detection technique, Hidden Markov Models (HMMs, to extract information from daily time series of stream temperature to diagnose patterns of stream drying. Specifically, we applied HMMs to time series of daily standard deviation (SD of stream temperature (i.e., dry stream channels typically display highly variable daily temperature records compared to wet stream channels between April and August (2015–2016. We used information from paired stream and air temperature data loggers as well as co-located stream temperature data loggers with electrical resistors as confirmatory sources of the timing of stream drying. We expanded our approach to an entire stream network to illustrate the utility of the method to detect patterns of flow permanence over a broader spatial extent. We successfully identified and separated signals characteristic of wet and dry stream conditions and their shifts over time. Most of our study sites within the entire stream network exhibited a single state over the entire season (80%, but a portion of them showed one or more shifts among states (17%. We provide recommendations to use this approach based on a series of simple steps. Our findings illustrate a successful method that can be used to rigorously quantify flow permanence regimes in streams using existing records of stream temperature.

  17. A statistical method to predict flow permanence in dryland streams from time series of stream temperature

    Science.gov (United States)

    Arismendi, Ivan; Dunham, Jason B.; Heck, Michael; Schultz, Luke; Hockman-Wert, David

    2017-01-01

    Intermittent and ephemeral streams represent more than half of the length of the global river network. Dryland freshwater ecosystems are especially vulnerable to changes in human-related water uses as well as shifts in terrestrial climates. Yet, the description and quantification of patterns of flow permanence in these systems is challenging mostly due to difficulties in instrumentation. Here, we took advantage of existing stream temperature datasets in dryland streams in the northwest Great Basin desert, USA, to extract critical information on climate-sensitive patterns of flow permanence. We used a signal detection technique, Hidden Markov Models (HMMs), to extract information from daily time series of stream temperature to diagnose patterns of stream drying. Specifically, we applied HMMs to time series of daily standard deviation (SD) of stream temperature (i.e., dry stream channels typically display highly variable daily temperature records compared to wet stream channels) between April and August (2015–2016). We used information from paired stream and air temperature data loggers as well as co-located stream temperature data loggers with electrical resistors as confirmatory sources of the timing of stream drying. We expanded our approach to an entire stream network to illustrate the utility of the method to detect patterns of flow permanence over a broader spatial extent. We successfully identified and separated signals characteristic of wet and dry stream conditions and their shifts over time. Most of our study sites within the entire stream network exhibited a single state over the entire season (80%), but a portion of them showed one or more shifts among states (17%). We provide recommendations to use this approach based on a series of simple steps. Our findings illustrate a successful method that can be used to rigorously quantify flow permanence regimes in streams using existing records of stream temperature.

  18. EVOLUTION OF INTERMITTENCY IN THE SLOW AND FAST SOLAR WIND BEYOND THE ECLIPTIC PLANE

    Energy Technology Data Exchange (ETDEWEB)

    Wawrzaszek, A.; Macek, W. M. [Space Research Centre, Polish Academy of Sciences, Warsaw (Poland); Echim, M. [The Belgian Institute for Space Aeronomy, Brussels (Belgium); Bruno, R., E-mail: anna.wawrzaszek@cbk.waw.pl, E-mail: marius.echim@oma.be, E-mail: macek@cbk.waw.pl, E-mail: roberto.bruno@iaps.inaf.it [Institute for Space Astrophysics and Planetology, Roma (Italy)

    2015-12-01

    We study intermittency as a departure from self-similarity of the solar wind magnetic turbulence and investigate the evolution with the heliocentric distance and latitude. We use data from the Ulysses spacecraft measured during two solar minima (1997–1998 and 2007–2008) and one solar maximum (1999–2001). In particular, by modeling a multifractal spectrum, we revealed the intermittent character of turbulence in the small-scale fluctuations of the magnetic field embedded in the slow and fast solar wind. Generally, at small distances from the Sun, in both the slow and fast solar wind, we observe the high degree of multifractality (intermittency) that decreases somewhat slowly with distance and slowly with latitude. The obtained results seem to suggest that generally intermittency in the solar wind has a solar origin. However, the fast and slow streams, shocks, and other nonlinear interactions can only be considered as the drivers of the intermittent turbulence. It seems that analysis shows that turbulence beyond the ecliptic plane evolves too slowly to maintain the intermittency with the distance and latitude. Moreover, we confirm that the multifractality and intermittency are at a lower level than in the ecliptic, as well as the existence of symmetry with respect to the ecliptic plane, suggesting that there are similar turbulent properties observed in the two hemispheres.

  19. EVOLUTION OF INTERMITTENCY IN THE SLOW AND FAST SOLAR WIND BEYOND THE ECLIPTIC PLANE

    International Nuclear Information System (INIS)

    Wawrzaszek, A.; Macek, W. M.; Echim, M.; Bruno, R.

    2015-01-01

    We study intermittency as a departure from self-similarity of the solar wind magnetic turbulence and investigate the evolution with the heliocentric distance and latitude. We use data from the Ulysses spacecraft measured during two solar minima (1997–1998 and 2007–2008) and one solar maximum (1999–2001). In particular, by modeling a multifractal spectrum, we revealed the intermittent character of turbulence in the small-scale fluctuations of the magnetic field embedded in the slow and fast solar wind. Generally, at small distances from the Sun, in both the slow and fast solar wind, we observe the high degree of multifractality (intermittency) that decreases somewhat slowly with distance and slowly with latitude. The obtained results seem to suggest that generally intermittency in the solar wind has a solar origin. However, the fast and slow streams, shocks, and other nonlinear interactions can only be considered as the drivers of the intermittent turbulence. It seems that analysis shows that turbulence beyond the ecliptic plane evolves too slowly to maintain the intermittency with the distance and latitude. Moreover, we confirm that the multifractality and intermittency are at a lower level than in the ecliptic, as well as the existence of symmetry with respect to the ecliptic plane, suggesting that there are similar turbulent properties observed in the two hemispheres

  20. Importance of vegetation, topography and flow paths for water transit times of base flow in alpine headwater catchments

    Directory of Open Access Journals (Sweden)

    M. H. Mueller

    2013-04-01

    Full Text Available The mean transit time (MTT of water in a catchment gives information about storage, flow paths, sources of water and thus also about retention and release of solutes in a catchment. To our knowledge there are only a few catchment studies on the influence of vegetation cover changes on base flow MTTs. The main changes in vegetation cover in the Swiss Alps are massive shrub encroachment and forest expansion into formerly open habitats. Four small and relatively steep headwater catchments in the Swiss Alps (Ursern Valley were investigated to relate different vegetation cover to water transit times. Time series of water stable isotopes were used to calculate MTTs. The high temporal variation of the stable isotope signals in precipitation was strongly dampened in stream base flow samples. MTTs of the four catchments were 70 to 102 weeks. The strong dampening of the stable isotope input signal as well as stream water geochemistry points to deeper flow paths and mixing of waters of different ages at the catchments' outlets. MTTs were neither related to topographic indices nor vegetation cover. The major part of the quickly infiltrating precipitation likely percolates through fractured and partially karstified deeper rock zones, which increases the control of bedrock flow paths on MTT. Snow accumulation and the timing of its melt play an important role for stable isotope dynamics during spring and early summer. We conclude that, in mountainous headwater catchments with relatively shallow soil layers, the hydrogeological and geochemical patterns (i.e. geochemistry, porosity and hydraulic conductivity of rocks and snow dynamics influence storage, mixing and release of water in a stronger way than vegetation cover or topography do.

  1. Sources, occurrence and predicted aquatic impact of legacy and contemporary pesticides in streams

    International Nuclear Information System (INIS)

    McKnight, Ursula S.; Rasmussen, Jes J.; Kronvang, Brian; Binning, Philip J.; Bjerg, Poul L.

    2015-01-01

    We couple current findings of pesticides in surface and groundwater to the history of pesticide usage, focusing on the potential contribution of legacy pesticides to the predicted ecotoxicological impact on benthic macroinvertebrates in headwater streams. Results suggest that groundwater, in addition to precipitation and surface runoff, is an important source of pesticides (particularly legacy herbicides) entering surface water. In addition to current-use active ingredients, legacy pesticides, metabolites and impurities are important for explaining the estimated total toxicity attributable to pesticides. Sediment-bound insecticides were identified as the primary source for predicted ecotoxicity. Our results support recent studies indicating that highly sorbing chemicals contribute and even drive impacts on aquatic ecosystems. They further indicate that groundwater contaminated by legacy and contemporary pesticides may impact adjoining streams. Stream observations of soluble and sediment-bound pesticides are valuable for understanding the long-term fate of pesticides in aquifers, and should be included in stream monitoring programs. - Highlights: • Findings comprised a range of contemporary and banned legacy pesticides in streams. • Groundwater is a significant pathway for some herbicides entering streams. • Legacy pesticides increased predicted aquatic toxicity by four orders of magnitude. • Sediment-bound insecticides were identified as the primary source for ecotoxicity. • Stream monitoring programs should include legacy pesticides to assess impacts. - Legacy pesticides, particularly sediment-bound insecticides were identified as the primary source for predicted ecotoxicity impacting benthic macroinvertebrates in headwater streams

  2. Small reservoir effects on headwater water quality in the rural-urban fringe, Georgia Piedmont, USA

    Directory of Open Access Journals (Sweden)

    Dr.. Amber R. Ignatius, Geographer

    2016-12-01

    Full Text Available Small reservoirs are prevalent landscape features that affect the physical, chemical, and biological characteristics of headwater streams. Tens of thousands of small reservoirs, often less than a hectare in size, were constructed over the past century within the United States. While remote-sensing and geographic-mapping technologies assist in identifying and quantifying these features, their localized influence on water quality is uncertain. We report a year-long physicochemical study of nine small reservoirs (0.15–2.17 ha within the Oconee and Broad River Watersheds in the Georgia Piedmont. Study sites were selected along an urban-rural gradient with differing amounts of agricultural, forested, and developed land covers. Sites were sampled monthly for discharge and inflow/outflow water quality parameters (temperature, specific conductance, pH, dissolved oxygen, turbidity, alkalinity, total phosphorus, total nitrogen, nitrate, ammonium. While the proportion of developed land cover within watersheds had positive correlations with reservoir specific conductivity values, agricultural and forested land covers showed correlations (positive and negative, respectively with reservoir alkalinity, total nitrogen, nitrate, and specific conductivity. The majority of outflow temperatures were warmer than inflows for all land uses throughout the year, especially in the summer. Outflows had lower nitrate concentrations, but higher ammonium. The type of outflow structure was also influential; top-release dams showed higher dissolved oxygen and pH than bottom-release dams. Water quality effects were still evident 250 m below the dam, albeit reduced.

  3. Stream permanence influences crayfish occupancy and abundance in the Ozark Highlands, USA

    Science.gov (United States)

    Yarra, Allyson N.; Magoulick, Daniel D.

    2018-01-01

    Crayfish use of intermittent streams is especially important to understand in the face of global climate change. We examined the influence of stream permanence and local habitat on crayfish occupancy and species densities in the Ozark Highlands, USA. We sampled in June and July 2014 and 2015. We used a quantitative kick–seine method to sample crayfish presence and abundance at 20 stream sites with 32 surveys/site in the Upper White River drainage, and we measured associated local environmental variables each year. We modeled site occupancy and detection probabilities with the software PRESENCE, and we used multiple linear regressions to identify relationships between crayfish species densities and environmental variables. Occupancy of all crayfish species was related to stream permanence. Faxonius meeki was found exclusively in intermittent streams, whereas Faxonius neglectus and Faxonius luteushad higher occupancy and detection probability in permanent than in intermittent streams, and Faxonius williamsi was associated with intermittent streams. Estimates of detection probability ranged from 0.56 to 1, which is high relative to values found by other investigators. With the exception of F. williamsi, species densities were largely related to stream permanence rather than local habitat. Species densities did not differ by year, but total crayfish densities were significantly lower in 2015 than 2014. Increased precipitation and discharge in 2015 probably led to the lower crayfish densities observed during this year. Our study demonstrates that crayfish distribution and abundance is strongly influenced by stream permanence. Some species, including those of conservation concern (i.e., F. williamsi, F. meeki), appear dependent on intermittent streams, and conservation efforts should include consideration of intermittent streams as an important component of freshwater biodiversity.

  4. Fish movement ecology in high gradient headwater streams: Its relevance to fish passage restoration through stream culvert barriers

    Science.gov (United States)

    Hoffman, Robert L.; Dunham, Jason B.

    2007-01-01

    Restoration of fish passage through culvert barriers has emerged as a major issue in the Pacific Northwest and nationwide, in part, because of their potential influence on fish movement. Movement is an essential mechanism by which mobile animals acquire the resources necessary for the successful completion of their life-cycles. In this report, we provide a brief review of some essential characteristics of animal movement and examples from a focal group of fishes in Washington State: salmon, trout, and char. We begin by outlining some basic characteristics of animal movement and then apply that foundation to the case of salmonid fishes. Next we consider the consequences of disrupting fish movement with human-constructed barriers, such as culverts. Finally, this body of evidence is summarized, and we propose a short list of what we view as high priority information needs to support more effective restoration of fish passage through culverts.

  5. Spatial and temporal variability of runoff and streamflow generation within and among headwater catchments: a combined hydrometric and stable isotope approach

    Science.gov (United States)

    Singh, N. K.; Emanuel, R. E.; McGlynn, B. L.

    2012-12-01

    The combined influence of topography and vegetation on runoff generation and streamflow in headwater catchments remains unclear. We aim to understand how spatial, hydrological and climate variables affect runoff generation and streamflow at hillslope and watershed scales at the Coweeta Hydrologic Laboratory (CHL) in the southern Appalachian Mountains by analyzing stable isotopes of hydrogen (2H) and oxygen (18O) coupled with measurements of hydrological variables (stream discharge, soil moisture, shallow groundwater) and landscape variables (upslope accumulated area, vegetation density slope, and aspect). We investigated four small catchments, two of which contained broadleaf deciduous vegetation and two of which contained evergreen coniferous vegetation. Beginning in June 2011, we collected monthly water samples at 25 m intervals along each stream, monthly samples from 24 shallow groundwater wells, and weekly to monthly samples from 10 rain gauges distributed across CHL. Water samples were analyzed for 2H and 18O using cavity ring-down spectroscopy. During the same time period we recorded shallow groundwater stage at 30 min intervals from each well, and beginning in fall 2011 we collected volumetric soil moisture data at 30 min intervals from multiple depths at 16 landscape positions. Results show high spatial and temporal variability in δ2H and δ18O within and among streams, but in general we found isotopic enrichment with increasing contributing area along each stream. We used a combination of hydrometric observations and geospatial analyses to understand why stream isotope patterns varied during the year and among watersheds, and we used complementary measurements of δ2H and δ18O from other pools within the watersheds to understand the movement and mixing of precipitation that precedes runoff formation. This combination of high resolution stable isotope data and hydrometric observations facilitates a clearer understanding of spatial controls on streamflow

  6. Floodplains as a source of fine sediment in grazed landscapes: Tracing the source of suspended sediment in the headwaters of an intensively managed agricultural landscape

    Science.gov (United States)

    Yu, Mingjing; Rhoads, Bruce L.

    2018-05-01

    The flux of fine sediment within agricultural watersheds is an important factor determining the environmental quality of streams and rivers. Despite this importance, the contributions of sediment sources to suspended sediment loads within intensively managed agricultural watersheds remain poorly understood. This study assesses the provenance of fine suspended sediment in the headwater portion of a river flowing through an agricultural landscape in Illinois. Sediment source samples were collected from five sources: croplands, forested floodplains, grasslands, upper grazed floodplains, and lower grazed floodplains. Event-based and aggregated suspended sediment samples were collected from the stream at the watershed outlet. Quantitative geochemical fingerprinting techniques and a mixing model were employed to estimate the relative contributions of sediment from the five sources to the suspended sediment loads. To account for possible effects of small sample sizes, the analysis was repeated with only two sources: grazed floodplains and croplands/grasslands/forested floodplains. Results based on mean values of tracers indicate that the vast majority of suspended sediment within the stream (>95%) is derived from erosion of channel banks and the soil surface within areas of grazed floodplains. Uncertainty analysis based on Monte Carlo simulations indicates that mean values of tracer properties, which do not account for sampling variability in these properties, probably overestimate contributions from the two major sources. Nevertheless, this analysis still supports the conclusion that floodplain erosion accounts for the largest percentage of instream sediment (≈55-75%). Although grazing occurs over only a small portion of the total watershed area, grazed floodplains, which lie in close proximity to the stream channel, are an important source of sediment in this headwater steam system. Efforts to reduce fluxes of fine sediment in this intensively managed landscape should

  7. The role of near-stream riparian zones in the hydrology of steep upland catchments

    Science.gov (United States)

    McDonnell, Jeffery J.; McGlynn, B.L.; Kendall, K.; Shanley, J.; Kendall, C.

    1998-01-01

    Surface and subsurface waters were monitored and sampled at various topographic positions in a 40.5-ha headwater catchment to test several hypotheses of runoff generation and stream chemical and isotopic evolution during snowmelt. Transmissivity feedback was observed on the hillslopes during the melt period. Groundwater levels and stream DOC were highly correlated with stream discharge. Hysteresis in the groundwater-streamflow relation suggests that localized water flux from the riparian areas controlled the rising limb and main peak response of the melt hydrograph, whilst hillslope drainage controlled the timing and volume of the falling limb. Lateral flow from upslope positions was detected in the riparian zone.

  8. Contribution of radioactive 137Cs discharge by suspended sediment, coarse organic matter, and dissolved fraction from a headwater catchment in Fukushima after the Fukushima Dai-ichi Nuclear Power Plant accident.

    Science.gov (United States)

    Iwagami, Sho; Onda, Yuichi; Tsujimura, Maki; Abe, Yutaka

    2017-01-01

    Radiocesium ( 137 Cs) migration from headwaters in forested areas provides important information, as the output from forest streams subsequently enters various land-use areas and downstream rivers. Thus, it is important to determine the composition of 137 Cs fluxes (dissolved fraction, suspended sediment, or coarse organic matter) that migrate through a headwater stream. In this study, the 137 Cs discharge by suspended sediment and coarse organic matter from a forest headwater catchment was monitored. The 137 Cs concentrations in suspended sediment and coarse organic matter, such as leaves and branches, and the amounts of suspended sediment and coarse organic matter were measured at stream sites in three headwater catchments in Yamakiya District, located ∼35 km northwest of Fukushima Dai-ichi Nuclear Power Plant (FDNPP) from August 2012 to September 2013, following the earthquake and tsunami disaster. Suspended sediment and coarse organic matter were sampled at intervals of approximately 1-2 months. The 137 Cs concentrations of suspended sediment and coarse organic matter were 2.4-49 kBq/kg and 0.85-14 kBq/kg, respectively. The 137 Cs concentrations of the suspended sediment were closely correlated with the average deposition density of the catchment. The annual proportions of contribution of 137 Cs discharge by suspended sediment, coarse organic matter, and dissolved fraction were 96-99%, 0.0092-0.069%, and 0.73-3.7%, respectively. The total annual 137 Cs discharge from the catchment was 0.02-0.3% of the deposition. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Groundwater Recharge and Flow Regime revealed by multi-tracers approach in a headwater, North China Plain

    Science.gov (United States)

    Sakakibara, Koichi; Tsujimura, Maki; Song, Xianfang; Zhang, Jie

    2014-05-01

    Groundwater recharge is a crucial hydrological process for effective water management especially in arid/ semi-arid regions. However, the insufficient number of specific research regarding groundwater recharge process has been reported previously. Intensive field surveys were conducted during rainy season, mid dry season, and end of dry season, in order to clarify comprehensive groundwater recharge and flow regime of Wangkuai watershed in a headwater, which is a main recharge zone of North China Plain. The groundwater, spring, stream water and lake water were sampled, and inorganic solute constituents and stable isotopes of oxygen 18 and deuterium were determined on all water samples. Also the stream flow rate was observed. The solute ion concentrations and stable isotopic compositions show that the most water of this region can be characterized by Ca-HCO3 type and the main water source is precipitation which is affected by altitude effect of stable isotopes. In addition, the river and reservoir of the area seem to recharge the groundwater during rainy season, whereas interaction between surface water and groundwater does not become dominant gradually after the rainy season. The inversion analysis applied in Wangkuai watershed using simple mixing model represents an existing multi-flow systems which shows a distinctive tracer signal and flow rate. In summary, the groundwater recharged at different locations in the upper stream of Wangkuai reservoir flows downward to alluvial fan with a certain amount of mixing together, also the surface water recharges certainly the groundwater in alluvial plain in the rainy season.

  10. Partitioning taxonomic diversity of aquatic insect assemblages and functional feeding groups in Neotropical Savanna headwater streams

    Science.gov (United States)

    Biological diversity can be divided into: alpha (α, local), beta (β, difference in assemblage composition among locals), and gamma (γ, total diversity). We assessed the partitioning of taxonomic diversity of Ephemeroptera, Plecoptera and Trichoptera (EPT) and of functional feedin...

  11. Nutrient enrichment alters storage and fluxes of detritus in a headwater stream ecosystem

    Science.gov (United States)

    Jonathan P. Benstead; Amy D. Rosemond; Wyatt F. Cross; J. Bruce Wallace; Susan L. Eggert; Keller Suberkropp; Vladislav Gulis; Jennifer L. Greenwood; Cynthia J. Tant

    2009-01-01

    Responses of detrital pathways to nutrients may differ fundamentally from pathways involving living plants: basal carbon resources can potentially decrease rather than increase with nutrient enrichment. Despite the potential for nutrients to accelerate heterotrophic processes and fluxes of detritus, few studies have examined detritus-nutrient dynamics at whole-...

  12. Characterization of storm flow dynamics of headwater streams in the South Carolina lower coastal plain

    Science.gov (United States)

    Thomas H. Epps; Daniel R. Hitchcock; Anand D. Jayakaran; Drake R. Loflin; Thomas M. Williams; Devendra M. Amatya

    2013-01-01

    Hydrologic monitoring was conducted in two first-order lower coastal plain watersheds in South Carolina, United States, a region with increasing growth and land use change. Storm events over a three-year period were analyzed for direct runoff coefficients (ROC) and the total storm response (TSR) as percent rainfall. ROC calculations utilized an empirical hydrograph...

  13. Ecosystem Function in Appalachian Headwater Streams during an Active Invasion by the Hemlock Woolly Adelgid

    Science.gov (United States)

    Robert M. Northington; Jackson R. Webster; Ernest F. Benfield; Beth M. Cheever; Barbara R. Niederlehner

    2013-01-01

    Forested ecosystems in the southeastern United States are currently undergoing an invasion by the hemlock woolly adelgid (HWA). Previous studies in this area have shown changes to forest structure, decreases in canopy cover, increases in organic matter, and changes to nutrient cycling on the forest floor and soil. Here, we were interested in how the effects of canopy...

  14. Trophic structure of fish fauna along the longitudinal gradient of a first-order rural stream

    Directory of Open Access Journals (Sweden)

    Jardel Nimet

    2015-12-01

    Full Text Available Abstract Aim: This study evaluated the trophic structure of the fish assemblage along the longitudinal gradient of a first-order rural stream. Methods Fish were sampled by electrofishing technique in December 2007, September 2008 and March 2009, at three stretch of the Itiz stream (headwater, middle and mouth. We sampled 1,255 individuals relating to 18 species. The categorization of trophic guilds was based on stomach content data of 1,096 individuals, analyzed according to the volumetric method, except for four species, which were classified according to the literature. To test the hypothesis of differences in the richness, abundance and biomass of trophic guilds along the headwater-mouth gradient, it was performed non-parametric statistical analysis of the dietary data. Was also calculated, the amplitude of trophic niche (Levins's index for each guild. To summarize the composition and abundance of the trophic guilds along the longitudinal gradient, we applied a non-metric multidimensional scaling (NMDS. Results We registered seven guilds: herbivorous, detritivorous, aquatic insectivorous, terrestrial insectivorous, invertivorous, omnivorous and piscivorous, the latter was exclusive to headwater and middle stretches. The omnivorous guild was not recorded in the headwater. Through PERMANOVA analysis it was found that the species richness of more specialized guilds (detritivorous and insectivorous terrestrial and of generalist invertivorous increased, while less specialized guilds like aquatic insectivorous and herbivorous, decrease significantly in headwater-mouth direction. Except by the non-expected increase of insectivorous terrestrial and decrease of herbivorous downstream, the non-metric multidimensional scaling (NMDS identified longitudinal variations in abundance and biomass of the guilds that agree with general patterns of fish guilds distribution along environmental gradients. Conclusion These results suggest that the influence of

  15. 78 FR 78717 - Reservoirs at Headwaters of the Mississippi River; Use and Administration

    Science.gov (United States)

    2013-12-27

    ... Headwaters of the Mississippi River; Use and Administration AGENCY: U.S. Army Corps of Engineers, DoD. ACTION... administration of the reservoirs at the headwaters of the Mississippi River by deleting from the Code of Federal... values that differ from those currently codified in the Code of Federal Regulations. Deleting all...

  16. Thermal and hydrologic responses to climate change predict marked alterations in boreal stream invertebrate assemblages.

    Science.gov (United States)

    Mustonen, Kaisa-Riikka; Mykrä, Heikki; Marttila, Hannu; Sarremejane, Romain; Veijalainen, Noora; Sippel, Kalle; Muotka, Timo; Hawkins, Charles P

    2018-06-01

    Air temperature at the northernmost latitudes is predicted to increase steeply and precipitation to become more variable by the end of the 21st century, resulting in altered thermal and hydrological regimes. We applied five climate scenarios to predict the future (2070-2100) benthic macroinvertebrate assemblages at 239 near-pristine sites across Finland (ca. 1200 km latitudinal span). We used a multitaxon distribution model with air temperature and modeled daily flow as predictors. As expected, projected air temperature increased the most in northernmost Finland. Predicted taxonomic richness also increased the most in northern Finland, congruent with the predicted northwards shift of many species' distributions. Compositional changes were predicted to be high even without changes in richness, suggesting that species replacement may be the main mechanism causing climate-induced changes in macroinvertebrate assemblages. Northern streams were predicted to lose much of the seasonality of their flow regimes, causing potentially marked changes in stream benthic assemblages. Sites with the highest loss of seasonality were predicted to support future assemblages that deviate most in compositional similarity from the present-day assemblages. Macroinvertebrate assemblages were also predicted to change more in headwaters than in larger streams, as headwaters were particularly sensitive to changes in flow patterns. Our results emphasize the importance of focusing protection and mitigation on headwater streams with high-flow seasonality because of their vulnerability to climate change. © 2018 John Wiley & Sons Ltd.

  17. From headwaters to coast: Influence of human activities on water quality of the Potomac River Estuary

    Science.gov (United States)

    Bricker, Suzanne B.; Rice, Karen C.; Bricker, Owen P.

    2014-01-01

    The natural aging process of Chesapeake Bay and its tributary estuaries has been accelerated by human activities around the shoreline and within the watershed, increasing sediment and nutrient loads delivered to the bay. Riverine nutrients cause algal growth in the bay leading to reductions in light penetration with consequent declines in sea grass growth, smothering of bottom-dwelling organisms, and decreases in bottom-water dissolved oxygen as algal blooms decay. Historically, bay waters were filtered by oysters, but declines in oyster populations from overfishing and disease have led to higher concentrations of fine-sediment particles and phytoplankton in the water column. Assessments of water and biological resource quality in Chesapeake Bay and tributaries, such as the Potomac River, show a continual degraded state. In this paper, we pay tribute to Owen Bricker’s comprehensive, holistic scientific perspective using an approach that examines the connection between watershed and estuary. We evaluated nitrogen inputs from Potomac River headwaters, nutrient-related conditions within the estuary, and considered the use of shellfish aquaculture as an in-the-water nutrient management measure. Data from headwaters, nontidal, and estuarine portions of the Potomac River watershed and estuary were analyzed to examine the contribution from different parts of the watershed to total nitrogen loads to the estuary. An eutrophication model was applied to these data to evaluate eutrophication status and changes since the early 1990s and for comparison to regional and national conditions. A farm-scale aquaculture model was applied and results scaled to the estuary to determine the potential for shellfish (oyster) aquaculture to mediate eutrophication impacts. Results showed that (1) the contribution to nitrogen loads from headwater streams is small (about 2 %) of total inputs to the Potomac River Estuary; (2) eutrophic conditions in the Potomac River Estuary have improved in

  18. Distribution of Chironomidae in a semiarid intermittent river of Brazil.

    Science.gov (United States)

    Farias, R L; Carvalho, L K; Medeiros, E S F

    2012-12-01

    The effects of the intermittency of water flow on habitat structure and substrate composition have been reported to create a patch dynamics for the aquatic fauna, mostly for that associated with the substrate. This study aims to describe the spatial distribution of Chironomidae in an intermittent river of semiarid Brazil and to associate assemblage composition with environmental variables. Benthic invertebrates were sampled during the wet and dry seasons using a D-shaped net (40 cm wide and 250 μm mesh), and the Chironomidae were identified to genus level. The most abundant genera were Tanytarsus, Polypedilum, and Saetheria with important contributions of the genera Procladius, Aedokritus, and Dicrotendipes. Richness and density were not significantly different between the study sites, and multiple regression showed that the variation in richness and density explained by the environmental variables was significant only for substrate composition. The composition of genera showed significant spatial segregation across the study sites. Canonical Correspondence Analysis showed significant correspondence between Chironomidae composition and the environmental variables, with submerged vegetation, elevation, and leaf litter being important predictors of the Chironomidae fauna. This study showed that Chironomidae presented important spatial variation along the river and that this variation was substantially explained by environmental variables associated with the habitat structure and river hierarchy. We suggest that the observed spatial segregation in the fauna results in the high diversity of this group of organisms in intermittent streams.

  19. Marine dispersal determines the genetic population structure of migratory stream fauna of Puerto Rico: evidence for island-scale population recovery processes

    Science.gov (United States)

    Benjamin D. Cook; Sofie Bernays; Catherine M. Pringle; Jane M. Hughes

    2009-01-01

    Various components of island stream faunas, including caridean shrimps, fish, and gastropods, undertake obligate amphidromous migration, whereby larvae are released in upstream freshwater reaches, drift downstream to estuaries or marine waters, then migrate upstream as postlarvae to freshwater adult habitats. Longitudinal migration from estuaries to headwaters is well...

  20. Ecology of endangered damselfly Coenagrion ornatum in post-mining streams in relation to their restoration

    OpenAIRE

    TICHÁNEK, Filip

    2016-01-01

    The thesis explores various aspects of ecology of endangered damselfly Coenagrion ornatum, the specialists for lowland headwaters, in post-mining streams of Radovesicka spoil. The first part of thesis is manuscript which has been already submitted in Journal of Insect Conservation. In the first part, we focused on population estimate of the local population using capture-recapture method, and explored its habitat requirements across life stages and spatial scales. In the next part, I assess m...

  1. Consequences of variation in stream-landscape connections for stream nitrate retention and export

    Science.gov (United States)

    Handler, A. M.; Helton, A. M.; Grimm, N. B.

    2017-12-01

    Hydrologic and material connections among streams, the surrounding terrestrial landscape, and groundwater systems fluctuate between extremes in dryland watersheds, yet the consequences of this variation for stream nutrient retention and export remain uncertain. We explored how seasonal variation in hydrologic connection among streams, landscapes, and groundwater affect nitrate and ammonium concentrations across a dryland stream network and how this variation mediates in-stream nitrate uptake and watershed export. We conducted spatial surveys of stream nitrate and ammonium concentration across the 1200 km2 Oak Creek watershed in central Arizona (USA). In addition, we conducted pulse releases of a solution containing biologically reactive sodium nitrate, with sodium chloride as a conservative hydrologic tracer, to estimate nitrate uptake rates in the mainstem (Q>1000 L/s) and two tributaries. Nitrate and ammonium concentrations generally increased from headwaters to mouth in the mainstem. Locally elevated concentrations occurred in spring-fed tributaries draining fish hatcheries and larger irrigation ditches, but did not have a substantial effect on the mainstem nitrogen load. Ambient nitrate concentration (as N) ranged from below the analytical detection limit of 0.005 mg/L to 0.43 mg/L across all uptake experiments. Uptake length—average stream distance traveled for a nutrient atom from the point of release to its uptake—at ambient concentration ranged from 250 to 704 m and increased significantly with higher discharge, both across streams and within the same stream on different experiment dates. Vertical uptake velocity and aerial uptake rate ranged from 6.6-10.6 mm min-1 and 0.03 to 1.4 mg N m-2 min-1, respectively. Preliminary analyses indicate potentially elevated nitrogen loading to the lower portion of the watershed during seasonal precipitation events, but overall, the capacity for nitrate uptake is high in the mainstem and tributaries. Ongoing work

  2. Estimated Perennial Streams of Idaho and Related Geospatial Datasets

    Science.gov (United States)

    Rea, Alan; Skinner, Kenneth D.

    2009-01-01

    The perennial or intermittent status of a stream has bearing on many regulatory requirements. Because of changing technologies over time, cartographic representation of perennial/intermittent status of streams on U.S. Geological Survey (USGS) topographic maps is not always accurate and (or) consistent from one map sheet to another. Idaho Administrative Code defines an intermittent stream as one having a 7-day, 2-year low flow (7Q2) less than 0.1 cubic feet per second. To establish consistency with the Idaho Administrative Code, the USGS developed regional regression equations for Idaho streams for several low-flow statistics, including 7Q2. Using these regression equations, the 7Q2 streamflow may be estimated for naturally flowing streams anywhere in Idaho to help determine perennial/intermittent status of streams. Using these equations in conjunction with a Geographic Information System (GIS) technique known as weighted flow accumulation allows for an automated and continuous estimation of 7Q2 streamflow at all points along a stream, which in turn can be used to determine if a stream is intermittent or perennial according to the Idaho Administrative Code operational definition. The selected regression equations were applied to create continuous grids of 7Q2 estimates for the eight low-flow regression regions of Idaho. By applying the 0.1 ft3/s criterion, the perennial streams have been estimated in each low-flow region. Uncertainty in the estimates is shown by identifying a 'transitional' zone, corresponding to flow estimates of 0.1 ft3/s plus and minus one standard error. Considerable additional uncertainty exists in the model of perennial streams presented in this report. The regression models provide overall estimates based on general trends within each regression region. These models do not include local factors such as a large spring or a losing reach that may greatly affect flows at any given point. Site-specific flow data, assuming a sufficient period of

  3. Techniques for Minimizing and Monitoring the Impact of Pipeline Construction on Coastal Streams

    Science.gov (United States)

    Thomas W. Mulroy; John R. Storrer; Vincent J. Semonsen; Michael L. Dungan

    1989-01-01

    This paper describes specific measures recently employed for protection of riparian resources during construction of an oil and gas pipeline that crossed coastal reaches of 23 perennial and intermittent streams between Point Conception and Gaviota in Santa Barbara County, California. Flumes were constructed to maintain stream flow; anchored straw bales and silt fences...

  4. Temporal variation of nitrate and phosphate transport in headwater catchments: the hydrological controls and land use alteration

    Directory of Open Access Journals (Sweden)

    T.-Y. Lee

    2013-04-01

    Full Text Available Oceania rivers are hotspots of DIN (dissolved inorganic nitrogen and DIP (dissolved inorganic phosphorus transport due to humid/warm climate, typhoon-induced episodic rainfall and high tectonic activity that create an environment favorable for high/rapid runoff and soil erosion. In spite of its uniqueness, effects of hydrologic controls and land use on the transport behaviors of DIN and DIP are rarely documented. A 2 yr monitoring study for DIN and DIP from three headwater catchments with different cultivation gradient (0 To 8.9% was implemented during a ~ 3 day interval with an additional monitoring campaign at a 3 h interval during typhoon periods. Results showed the DIN yields in the pristine, moderately cultivated (2.7%, and intensively cultivated (8.9% watersheds were 8.3, 26, and 37 kg N ha−1 yr−1, respectively. For the DIP yields, they were 0.36, 0.35, and 0.56 kg P ha−1 yr−1, respectively. Higher year-round DIN concentrations and five times larger in DIN yields in intensively cultivated watersheds indicate DIN is more sensitive to land use changes. The high background DIN yield from the relatively pristine watershed was likely due to high atmospheric nitrogen deposition and large subterranean N pool. The correlations between runoff and concentration reveals that typhoon floods purge out more DIN from the subterranean reservoir, i.e., soil, by contrast, runoff washes off surface soil resulting in higher suspended sediment with higher DIP. Collectively, typhoon runoff contributes 20–70% and 47–80%, respectively, to the annual DIN and DIP exports. The DIN yield to DIP yield ratio varied from 97 to 410, which is higher than the global mean of ~ 18. Such a high ratio indicates a P-limiting condition in stream and the downstream aquatic environment. Based on our field observation, we constructed a conceptual model illustrating different remobilization mechanisms for DIN and DIP from headwaters in a mountainous river, which is

  5. A Guide to Ordinary High Water Mark (OHWM) Delineation for Non-Perennial Streams in the Western Mountains, Valleys, and Coast Region of the United States

    Science.gov (United States)

    2014-08-01

    38 15 Remotely sensed images acquired from Google Earth and ground-based images from 2011 of a non-perennial stream in Teton County, WY...less confined. Debris flows and landslides are common in the region, accounting for much, if not most, of the sediment flux from headwater streams in...information is becoming in- creasingly available and easy to analyze via free, open-access resources such as Google Earth (www.earth.google.com). Where

  6. Effects of groundwater levels and headwater wetlands on streamflow in the Charlie Creek basin, Peace River watershed, west-central Florida

    Science.gov (United States)

    Lee, T.M.; Sacks, L.A.; Hughes, J.D.

    2010-01-01

    storage, rainfall-runoff processes, and groundwater-level differences in the upper basin allow it to generate approximately half of the streamflow from the Charlie Creek basin. Therefore, future development in the upper basin that would alter the hydraulic connectivity of wetlands during high flow conditions or expand recharging groundwater conditions could substantially affect streamflow in Charlie Creek. LIDAR (Light detection and ranging) based topographic maps and integrated modeling results were used to quantify the water stored in wetlands and other topographic depressions, and to describe the network of shallow stream channels connecting wetlands to Charlie Creek and its tributaries over distances of several thousand feet. Peak flows at all but one streamflow station were underpredicted in MIKE SHE simulations, possibly because the hydraulics of surface channels connecting wetlands to stream channels were not explicitly simulated in the model. Explicitly simulating the smaller channels connecting wetlands and stream channels should improve the ability of future watershed models to simulate peak flows in streams with headwater wetlands. The runoff potential was greater in the lower half of the Charlie Creek basin than in the upper half, and the streambed of Charlie Creek had greater potential to both directly gain streamflow from groundwater and lose streamflow to groundwater. Charlie Creek is more incised into the surficial aquifer in the lower basin than in the upper basin, and the streambed intersects the top of the intermediate aquifer system at two known locations. Groundwater levels in the intermediate aquifer system varied widely in the lower half of the basin from artesian conditions inducing upward flow toward the surficial aquifer and streams, to recharging conditions allowing downward flow and stream leakage. Recharge areas were greatest in May 2004 when rainfall was at a seasonal low and irrigation pumping was at a seasonal high. Recharge conditions

  7. Implementation of Environmental Flows for Intermittent River Systems: Adaptive Management and Stakeholder Participation Facilitate Implementation

    Science.gov (United States)

    Conallin, John; Wilson, Emma; Campbell, Josh

    2018-03-01

    Anthropogenic pressure on freshwater ecosystems is increasing, and often leading to unacceptable social-ecological outcomes. This is even more prevalent in intermittent river systems where many are already heavily modified, or human encroachment is increasing. Although adaptive management approaches have the potential to aid in providing the framework to consider the complexities of intermittent river systems and improve utility within the management of these systems, success has been variable. This paper looks at the application of an adaptive management pilot project within an environmental flows program in an intermittent stream (Tuppal Creek) in the Murray Darling Basin, Australia. The program focused on stakeholder involvement, participatory decision-making, and simple monitoring as the basis of an adaptive management approach. The approach found that by building trust and ownership through concentrating on inclusiveness and transparency, partnerships between government agencies and landholders were developed. This facilitated a willingness to accept greater risks and unintended consequences allowing implementation to occur.

  8. South Platte Watershed from the Headwaters to the Denver Metropolitan Area (Colorado) Systems Thinking

    Science.gov (United States)

    South Platte Watershed from the Headwaters to the Denver Metropolitan Area (Colorado) of the Urban Waters Federal Partnership (UWFP) reconnects urban communities with their waterways by improving coordination among federal agencies and collaborating

  9. 76 FR 55699 - Proposed Establishment of Everglades Headwaters National Wildlife Refuge and Conservation Area

    Science.gov (United States)

    2011-09-08

    ... Federal trust species and species of management concern, with special emphasis on species listed under the... landscape; (6) protect the headwaters, groundwater recharge, and watershed of the Kissimmee Chain of Lakes...

  10. Bioassessment in nonperennial streams: Hydrologic stability influences assessment validity

    Science.gov (United States)

    Mazor, R. D.; Stein, E. D.; Schiff, K.; Ode, P.; Rehn, A.

    2011-12-01

    Nonperennial streams pose a challenge for bioassessment, as assessment tools developed in perennial streams may not work in these systems. For example, indices of biotic integrity (IBIs) developed in perennial streams may give improper indications of impairment in nonperennial streams, or may be unstable. We sampled benthic macroinvertebrates from 12 nonperennial streams in southern California. In addition, we deployed loggers to obtain continuous measures of flow. 3 sites were revisited over 2 years. For each site, we calculated several metrics, IBIs, and O/E scores to determine if assessments were consistent and valid throughout the summer. Hydrology varied widely among the streams, with several streams drying between sampling events. IBIs suggested good ecological health at the beginning of the study, but declined sharply at some sites. Multivariate ordination suggested that, despite differences among sites, changes in community structure were similar, with shifts from Ephemeroptera, Plecoptera, and Trichoptera to Coleoptera and more tolerant organisms. Site revisits revealed a surprising level of variability, as 2 of the 3 revisited sites had perennial or near-perennial flow in the second year of sampling. IBI scores were more consistent in streams with stable hydrographs than in those with strongly intermittent hydrographs. These results suggest that nonperennial streams can be monitored successfully, but they may require short index periods and distinct metrics from those used in perennial streams. In addition, better approaches to mapping nonperennial streams are required.

  11. Geology, Streamflow, and Water Chemistry of the Talufofo Stream Basin, Saipan, Northern Mariana Islands

    Science.gov (United States)

    Izuka, Scot K.; Ewart, Charles J.

    1995-01-01

    A study of the geology, streamflow, and water chemistry of Talufofo Stream Basin, Saipan, Commonwealth of the Northern Mariana Islands, was undertaken to determine the flow characteristics of Talufofo Stream and the relation to the geology of the drainage basin. The Commonwealth government is exploring the feasibility of using water from Talufofo Stream to supplement Saipan's stressed municipal water supply. Streamflow records from gaging stations on the principal forks of Talufofo Stream indicate that peak streamflows and long-term average flow are higher at the South Fork gaging station than at the Middle Fork gaging station because the drainage area of the South Fork gaging station is larger, but persistent base flow from ground-water discharge during dry weather is greater in the Middle Fork gaging station. The sum of the average flows at the Middle Fork and South Fork gaging stations, plus an estimate of the average flow at a point in the lower reaches of the North Fork, is about 2.96 cubic feet per second or 1.91 million gallons per day. Although this average represents the theoretical maximum long-term draft rate possible from the Talufofo Stream Basin if an adequate reservoir can be built, the actual amount of surface water available will be less because of evaporation, leaks, induced infiltration, and reservoir-design constraints. Base-flow characteristics, such as stream seepage and spring discharge, are related to geology of the basin. Base flow in the Talufofo Stream Basin originates as discharge from springs near the base of limestones located in the headwaters of Talufofo Stream, flows over low-permeability volcanic rocks in the middle reaches, and seeps back into the high-permeability limestones in the lower reaches. Water sampled from Talufofo Stream during base flow had high dissolved-calcium concentrations (between 35 and 98 milligrams per liter), characteristic of water from a limestone aquifer. Concentrations of potassium, sodium, and chloride

  12. Design tradeoffs in long-term research for stream salamanders

    Science.gov (United States)

    Brand, Adrianne B,; Grant, Evan H. Campbell

    2017-01-01

    Long-term research programs can benefit from early and periodic evaluation of their ability to meet stated objectives. In particular, consideration of the spatial allocation of effort is key. We sampled 4 species of stream salamanders intensively for 2 years (2010–2011) in the Chesapeake and Ohio Canal National Historical Park, Maryland, USA to evaluate alternative distributions of sampling locations within stream networks, and then evaluated via simulation the ability of multiple survey designs to detect declines in occupancy and to estimate dynamic parameters (colonization, extinction) over 5 years for 2 species. We expected that fine-scale microhabitat variables (e.g., cobble, detritus) would be the strongest determinants of occupancy for each of the 4 species; however, we found greater support for all species for models including variables describing position within the stream network, stream size, or stream microhabitat. A monitoring design focused on headwater sections had greater power to detect changes in occupancy and the dynamic parameters in each of 3 scenarios for the dusky salamander (Desmognathus fuscus) and red salamander (Pseudotriton ruber). Results for transect length were more variable, but across all species and scenarios, 25-m transects are most suitable as a balance between maximizing detection probability and describing colonization and extinction. These results inform sampling design and provide a general framework for setting appropriate goals, effort, and duration in the initial planning stages of research programs on stream salamanders in the eastern United States.

  13. Tropical montane forest conversion affects spatial and temporal nitrogen dynamics in Kenyan headwater catchment

    Science.gov (United States)

    Jacobs, Suzanne; Weeser, Björn; Breuer, Lutz; Butterbach-Bahl, Klaus; Guzha, Alphonce; Rufino, Mariana

    2017-04-01

    Deforestation and land use change (LUC) are often stated as major contributors to changes in water quality, although other catchment characteristics such as topography, geology and climate can also play a role. Understanding how stream water chemistry is affected by LUC is essential for sustainable water management and land use planning. However, there is often a lack of reliable data, especially in less studied regions such as East Africa. This study focuses on three sub-catchments (27-36 km2) with different land use types (natural forest, smallholder agriculture and tea/tree plantations) nested in a 1023 km2 headwater catchment in the Mau Forest Complex, Kenya's largest closed-canopy indigenous tropical montane forest. In the past decades approx. 25% of the natural forest was lost due to land use change. We studied seasonal, diurnal and spatial patterns of total dissolved nitrogen (TDN), nitrate (NO3-N) and dissolved organic nitrogen (DON) using a combination of high-resolution in-situ measurements, bi-weekly stream water samples and spatial sampling campaigns. Multiple linear regression analysis of the spatial data indicates that land use shows a strong influence on TDN and nitrate, while DON is more influenced by precipitation. Highest TDN and nitrate concentrations are found in tea plantations, followed by smallholder agriculture and natural forest. This ranking does not change throughout the year, though concentrations of TDN and nitrate are respectively 27.6 and 25.4% lower in all catchments during the dry season. Maximum Overlap Discrete Wavelet Transform (MODWT) analysis of the high resolution nitrate data revealed a seasonal effect on diurnal patterns in the natural forest catchment, where the daily peak shifts from early morning in the wet season to mid-afternoon in the dry season. The smallholder and tea catchment do not exhibit clear diurnal patterns. The results suggest that land use affects dissolved nitrogen concentrations, leading to higher N

  14. Decoupling of stream and vegetation solutes during the late stages of weathering: insights from elemental and Mg isotope trends at the Luquillo Critical Zone Observatory, Puerto Rico

    Science.gov (United States)

    Chapela Lara, M.; Schuessler, J. A.; Buss, H. L.; McDowell, W. H.

    2017-12-01

    During the evolution of the critical zone, the predominant source of nutrients to the vegetation changes from bedrock weathering to atmospheric inputs and biological recycling. In parallel, the architecture of the critical zone changes with time, promoting a change in water flow regime from near-surface porous flow during early weathering stages to more complex flow regimes modulated by clay-rich regolith during the late stages of weathering. As a consequence of these two concurrent processes, we can expect the predominant sources and pathways of solutes to the streams to also change during critical zone evolution. If this is true, we would observe a decoupling between the solutes used by the vegetation and those that determine the composition of the streams during the late stages of weathering, represented by geomorphically stable tropical settings. To test these hypotheses, we are analyzing the elemental and Mg isotopic composition of regolith and streams at the humid tropical Luquillo Critical Zone Observatory. We aim to trace the relative contributions of the surficial, biologically mediated pathways and the deeper, weathering controlled nutrient pathways. We also investigate the role of lithology on the solute decoupling between the vegetation and the stream, by examining two similar headwater catchments draining two different bedrocks (andesitic volcaniclastic and granitic). Our preliminary elemental and Mg isotope results are consistent with atmospheric inputs in the upper 2 m of regolith in both lithologies and with bedrock weathering at depth. During a short storm event ( 6 h), a headwater stream draining volcaniclastic bedrock showed a large variation in Mg and δ26Mg, correlated with total suspended solids, while another similar headwater granitic stream showed a much narrower variation. A larger stream draining volcaniclastic bedrock showed changes in Mg concentration in response to rain during the same storm event, but did not change in δ26Mg

  15. The Yo-Yo intermittent recovery test

    DEFF Research Database (Denmark)

    Bangsbo, Jens; Iaia, F. Marcello; Krustrup, Peter

    2008-01-01

    The two Yo-Yo intermittent recovery (IR) tests evaluate an individual's ability to repeatedly perform intense exercise. The Yo-Yo IR level 1 (Yo-Yo IR1) test focuses on the capacity to carry out intermittent exercise leading to a maximal activation of the aerobic system, whereas Yo-Yo IR level 2...

  16. Intermittent behavior of the logistic system

    Science.gov (United States)

    Mayer-Kress, G.; Haken, H.

    1981-03-01

    In the discrete logistic model a transition to chaotic behavior via intermittency occurs in a neighborhood of periodic bands. Intermittent behavior is also induced if a stable periodic orbit is perturbed by low-level external noise, whereas alterations due to computer digitalisation produce remarkable periodicities. We compare our numerical results with the predictions of Pomeau and Manneville for the Lorenz system.

  17. Seasonal variation of residence time in spring and groundwater evaluated by CFCs and numerical simulation in mountainous headwater catchment

    Science.gov (United States)

    Tsujimura, Maki; Watanabe, Yasuto; Ikeda, Koichi; Yano, Shinjiro; Abe, Yutaka

    2016-04-01

    Headwater catchments in mountainous region are the most important recharge area for surface and subsurface waters, additionally time information of the water is principal to understand hydrological processes in the catchments. However, there have been few researches to evaluate variation of residence time of subsurface water in time and space at the mountainous headwaters especially with steep slope. We investigated the temporal variation of the residence time of the spring and groundwater with tracing of hydrological flow processes in mountainous catchments underlain by granite, Yamanashi Prefecture, central Japan. We conducted intensive hydrological monitoring and water sampling of spring, stream and ground waters in high-flow and low-flow seasons from 2008 through 2013 in River Jingu Watershed underlain by granite, with an area of approximately 15 km2 and elevation ranging from 950 m to 2000 m. The CFCs, stable isotopic ratios of oxygen-18 and deuterium, inorganic solute constituent concentrations were determined on all water samples. Also, a numerical simulation was conducted to reproduce of the average residence times of the spring and groundwater. The residence time of the spring water estimated by the CFCs concentration ranged from 10 years to 60 years in space within the watershed, and it was higher (older) during the low flow season and lower (younger) during the high flow season. We tried to reproduce the seasonal change of the residence time in the spring water by numerical simulation, and the calculated residence time of the spring water and discharge of the stream agreed well with the observed values. The groundwater level was higher during the high flow season and the groundwater dominantly flowed through the weathered granite with higher permeability, whereas that was lower during the low flow season and that flowed dominantly through the fresh granite with lower permeability. This caused the seasonal variation of the residence time of the spring

  18. Stream Phosphorus Dynamics Along a Suburbanizing Gradient in Southern Ontario, Canada

    Science.gov (United States)

    Duval, T. P.

    2017-12-01

    While it is well known that urban streams are subject to impaired water quality relative to natural analogues, far less research has been directed at stream water quality during the process of (sub-) urbanization. This study determines the role of housing construction activities in Brampton, Canada on the concentration and flux of phosphorus (P) of a headwater stream. Prior to development the stream was engineered with a riffle-pool sequence, riparian plantings, and a floodplain corridor that was lined with sediment fencing. Stream sites were sampled daily over a period of six months at locations representing varying stages of subdivision completion (upper site -active construction; middle site -finished construction and natural vegetation; lower site -finished construction and active construction). A nearby urban stream site developed ten years prior to this study was selected as a reference site. There were no differences in total phosphorus (TP) levels or flux between the suburbanizing and urban streams; however, the forms of P differed between sites. The urban stream TP load was dominated by particulate phosphorus (PP) while suburbanizing stream P was mainly in the dissolved organic phosphorus (DOP) form. The importance of DOP to TP flux increased with the onset of the growing season. TP levels in all stream segments frequently exceeded provincial water quality guidelines during storm events but were generally low during baseflow conditions. During storm events PP and total suspended solid levels in the suburbanizing stream reached levels of the urban stream due to sediment fence failure at several locations along the construction-hillslope interface. Along the suburbanizing gradient, the hydrological connection to a mid-reach zone of no-construction activity / fallow field and native forest resulted in significantly lower P levels than the upper suburbanizing stream site. This suggests that stream channel design features as well as timing of construction

  19. Cosmic Rays in Intermittent Magnetic Fields

    International Nuclear Information System (INIS)

    Shukurov, Anvar; Seta, Amit; Bushby, Paul J.; Wood, Toby S.; Snodin, Andrew P.

    2017-01-01

    The propagation of cosmic rays in turbulent magnetic fields is a diffusive process driven by the scattering of the charged particles by random magnetic fluctuations. Such fields are usually highly intermittent, consisting of intense magnetic filaments and ribbons surrounded by weaker, unstructured fluctuations. Studies of cosmic-ray propagation have largely overlooked intermittency, instead adopting Gaussian random magnetic fields. Using test particle simulations, we calculate cosmic-ray diffusivity in intermittent, dynamo-generated magnetic fields. The results are compared with those obtained from non-intermittent magnetic fields having identical power spectra. The presence of magnetic intermittency significantly enhances cosmic-ray diffusion over a wide range of particle energies. We demonstrate that the results can be interpreted in terms of a correlated random walk.

  20. Cosmic Rays in Intermittent Magnetic Fields

    Energy Technology Data Exchange (ETDEWEB)

    Shukurov, Anvar; Seta, Amit; Bushby, Paul J.; Wood, Toby S. [School of Mathematics and Statistics, Newcastle University, Newcastle Upon Tyne NE1 7RU (United Kingdom); Snodin, Andrew P., E-mail: a.seta1@ncl.ac.uk, E-mail: amitseta90@gmail.com [Department of Mathematics, Faculty of Applied Science, King Mongkut’s University of Technology North Bangkok, Bangkok 10800 (Thailand)

    2017-04-10

    The propagation of cosmic rays in turbulent magnetic fields is a diffusive process driven by the scattering of the charged particles by random magnetic fluctuations. Such fields are usually highly intermittent, consisting of intense magnetic filaments and ribbons surrounded by weaker, unstructured fluctuations. Studies of cosmic-ray propagation have largely overlooked intermittency, instead adopting Gaussian random magnetic fields. Using test particle simulations, we calculate cosmic-ray diffusivity in intermittent, dynamo-generated magnetic fields. The results are compared with those obtained from non-intermittent magnetic fields having identical power spectra. The presence of magnetic intermittency significantly enhances cosmic-ray diffusion over a wide range of particle energies. We demonstrate that the results can be interpreted in terms of a correlated random walk.

  1. The Role of Stream Water Carbon Dynamics and Export in the Carbon Balance of a Tropical Seasonal Rainforest, Southwest China

    Science.gov (United States)

    Zhou, Wen-Jun; Zhang, Yi-Ping; Schaefer, Douglas A.; Sha, Li-Qing; Deng, Yun; Deng, Xiao-Bao; Dai, Kai-Jie

    2013-01-01

    A two-year study (2009 ∼ 2010) was carried out to investigate the dynamics of different carbon (C) forms, and the role of stream export in the C balance of a 23.4-ha headwater catchment in a tropical seasonal rainforest at Xishuangbanna (XSBN), southwest China. The seasonal volumetric weighted mean (VWM) concentrations of total inorganic C (TIC) and dissolved inorganic C (DIC) were higher, and particulate inorganic C (PIC) and organic C (POC) were lower, in the dry season than the rainy season, while the VWM concentrations of total organic C (TOC) and dissolved organic C (DOC) were similar between seasons. With increased monthly stream discharge and stream water temperature (SWT), only TIC and DIC concentrations decreased significantly. The most important C form in stream export was DIC, accounting for 51.8% of the total C (TC) export; DOC, POC, and PIC accounted for 21.8%, 14.9%, and 11.5% of the TC export, respectively. Dynamics of C flux were closely related to stream discharge, with the greatest export during the rainy season. C export in the headwater stream was 47.1 kg C ha−1 yr−1, about 2.85% of the annual net ecosystem exchange. This finding indicates that stream export represented a minor contribution to the C balance in this tropical seasonal rainforest. PMID:23437195

  2. The role of stream water carbon dynamics and export in the carbon balance of a tropical seasonal rainforest, southwest China.

    Directory of Open Access Journals (Sweden)

    Wen-Jun Zhou

    Full Text Available A two-year study (2009 ~ 2010 was carried out to investigate the dynamics of different carbon (C forms, and the role of stream export in the C balance of a 23.4-ha headwater catchment in a tropical seasonal rainforest at Xishuangbanna (XSBN, southwest China. The seasonal volumetric weighted mean (VWM concentrations of total inorganic C (TIC and dissolved inorganic C (DIC were higher, and particulate inorganic C (PIC and organic C (POC were lower, in the dry season than the rainy season, while the VWM concentrations of total organic C (TOC and dissolved organic C (DOC were similar between seasons. With increased monthly stream discharge and stream water temperature (SWT, only TIC and DIC concentrations decreased significantly. The most important C form in stream export was DIC, accounting for 51.8% of the total C (TC export; DOC, POC, and PIC accounted for 21.8%, 14.9%, and 11.5% of the TC export, respectively. Dynamics of C flux were closely related to stream discharge, with the greatest export during the rainy season. C export in the headwater stream was 47.1 kg C ha(-1 yr(-1, about 2.85% of the annual net ecosystem exchange. This finding indicates that stream export represented a minor contribution to the C balance in this tropical seasonal rainforest.

  3. Application of the Hydroecological Integrity Assessment Process for Missouri Streams

    Science.gov (United States)

    Kennen, Jonathan G.; Henriksen, James A.; Heasley, John; Cade, Brian S.; Terrell, James W.

    2009-01-01

    Natural flow regime concepts and theories have established the justification for maintaining or restoring the range of natural hydrologic variability so that physiochemical processes, native biodiversity, and the evolutionary potential of aquatic and riparian assemblages can be sustained. A synthesis of recent research advances in hydroecology, coupled with stream classification using hydroecologically relevant indices, has produced the Hydroecological Integrity Assessment Process (HIP). HIP consists of (1) a regional classification of streams into hydrologic stream types based on flow data from long-term gaging-station records for relatively unmodified streams, (2) an identification of stream-type specific indices that address 11 subcomponents of the flow regime, (3) an ability to establish environmental flow standards, (4) an evaluation of hydrologic alteration, and (5) a capacity to conduct alternative analyses. The process starts with the identification of a hydrologic baseline (reference condition) for selected locations, uses flow data from a stream-gage network, and proceeds to classify streams into hydrologic stream types. Concurrently, the analysis identifies a set of non-redundant and ecologically relevant hydrologic indices for 11 subcomponents of flow for each stream type. Furthermore, regional hydrologic models for synthesizing flow conditions across a region and the development of flow-ecology response relations for each stream type can be added to further enhance the process. The application of HIP to Missouri streams identified five stream types ((1) intermittent, (2) perennial runoff-flashy, (3) perennial runoff-moderate baseflow, (4) perennial groundwater-stable, and (5) perennial groundwater-super stable). Two Missouri-specific computer software programs were developed: (1) a Missouri Hydrologic Assessment Tool (MOHAT) which is used to establish a hydrologic baseline, provide options for setting environmental flow standards, and compare past and

  4. ANISOTROPIC INTERMITTENCY OF MAGNETOHYDRODYNAMIC TURBULENCE

    International Nuclear Information System (INIS)

    Osman, K. T.; Kiyani, K. H.; Chapman, S. C.; Hnat, B.

    2014-01-01

    A higher-order multiscale analysis of spatial anisotropy in inertial range magnetohydrodynamic turbulence is presented using measurements from the STEREO spacecraft in fast ambient solar wind. We show for the first time that, when measuring parallel to the local magnetic field direction, the full statistical signature of the magnetic and Elsässer field fluctuations is that of a non-Gaussian globally scale-invariant process. This is distinct from the classic multiexponent statistics observed when the local magnetic field is perpendicular to the flow direction. These observations are interpreted as evidence for the weakness, or absence, of a parallel magnetofluid turbulence energy cascade. As such, these results present strong observational constraints on the statistical nature of intermittency in turbulent plasmas

  5. Prolonged Intermittent Renal Replacement Therapy.

    Science.gov (United States)

    Edrees, Fahad; Li, Tingting; Vijayan, Anitha

    2016-05-01

    Prolonged intermittent renal replacement therapy (PIRRT) is becoming an increasingly popular alternative to continuous renal replacement therapy in critically ill patients with acute kidney injury. There are significant practice variations in the provision of PIRRT across institutions, with respect to prescription, technology, and delivery of therapy. Clinical trials have generally demonstrated that PIRRT is non-inferior to continuous renal replacement therapy regarding patient outcomes. PIRRT offers cost-effective renal replacement therapy along with other advantages such as early patient mobilization and decreased nursing time. However, due to lack of standardization of the procedure, PIRRT still poses significant challenges, especially pertaining to appropriate drug dosing. Future guidelines and clinical trials should work toward developing consensus definitions for PIRRT and ensure optimal delivery of therapy. Copyright © 2016 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.

  6. A method to assess longitudinal riverine connectivity in tropical streams dominated by migratory biota

    Science.gov (United States)

    Crook, K.E.; Pringle, C.M.; Freeman, Mary C.

    2009-01-01

    1. One way in which dams affect ecosystem function is by altering the distribution and abundance of aquatic species. 2. Previous studies indicate that migratory shrimps have significant effects on ecosystem processes in Puerto Rican streams, but are vulnerable to impediments to upstream or downstream passage, such as dams and associated water intakes where stream water is withdrawn for human water supplies. Ecological effects of dams and water withdrawals from streams depend on spatial context and temporal variability of flow in relation to the amount of water withdrawn. 3. This paper presents a conceptual model for estimating the probability that an individual shrimp is able to migrate from a stream's headwaters to the estuary as a larva, and then return to the headwaters as a juvenile, given a set of dams and water withdrawals in the stream network. The model is applied to flow and withdrawal data for a set of dams and water withdrawals in the Caribbean National Forest (CNF) in Puerto Rico. 4. The index of longitudinal riverine connectivity (ILRC), is used to classify 17 water intakes in streams draining the CNF as having low, moderate, or high connectivity in terms of shrimp migration in both directions. An in-depth comparison of two streams showed that the stream characterized by higher water withdrawal had low connectivity, even during wet periods. Severity of effects is illustrated by a drought year, where the most downstream intake caused 100% larval shrimp mortality 78% of the year. 5. The ranking system provided by the index can be used as a tool for conservation ecologists and water resource managers to evaluate the relative vulnerability of migratory biota in streams, across different scales (reach-network), to seasonally low flows and extended drought. This information can be used to help evaluate the environmental tradeoffs of future water withdrawals. ?? 2008 John Wiley & Sons, Ltd.

  7. Potential interaction between transport and stream networks over the lowland rivers in Eastern India.

    Science.gov (United States)

    Roy, Suvendu; Sahu, Abhay Sankar

    2017-07-15

    Extension of transport networks supports good accessibility and associated with the development of a region. However, transport lines have fragmented the regional landscape and disturbed the natural interplay between rivers and their floodplains. Spatial analysis using multiple buffers provides information about the potential interaction between road and stream networks and their impact on channel morphology of a small watershed in the Lower Gangetic Plain. Present study is tried to understand the lateral and longitudinal disconnection in headwater stream by rural roads with the integration of geoinformatics and field survey. Significant (p development, delineation of stream corridor, regular monitoring and engineering efficiency for the construction of road and road-stream crossing might be effective in managing river geomorphology and riverine landscape. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Nutrient cycling and ecosystem metabolism in boreal streams of the Central Siberian Plateau

    Science.gov (United States)

    Diemer, L.; McDowell, W. H.; Prokushkin, A. S.

    2013-12-01

    Arctic boreal streams are undergoing considerable change in carbon and nutrient biogeochemistry due to degrading permafrost and increasing fire activity. Recent studies show that fire increases transport of inorganic solutes from the boreal landscape to arctic streams in some regions; couple this with expected greater labile dissolved organic carbon (DOC) from deepening active layers, enhanced biomass production, and increased annual precipitation and boreal streams may experience greater in-stream primary production and respiration in the coming century. Little is known about the spatial and temporal dynamics of inorganic nutrients in relation to C availability in headwater streams of a major Arctic region, the Central Siberian Plateau. Our preliminary data of Central Siberian headwater streams show NO3 and PO4 concentrations near or below detection limits (e.g. nine samples taken in spring from a small stream near the Russian settlement of Tura averaged 10 μg/L NO3-N and 9.7 μg/L PO4-P), and recent studies in Central Siberia suggest that bioavailable organic matter and inorganic nutrients such as NO3 will likely increase with climate warming. We examined the fate of nutrients in Central Siberian streams using Tracer for Spiraling Curve Characterization (TASCC) additions of NO3, NH4, and PO4 along with conservative tracer, NaCl, in spring at high and low discharges in streams underlain by continuous permafrost in Central Siberia. We also sampled two sites in spring every 2 hours overnight for 24 hours to document any diel patterns in DOC and inorganic nutrients. Our results thus far show that NO3 uptake length may be strongly correlated with DOC concentration (a function of fire activity). Preliminary results also show that despite high discharge and cold temperatures (4-8°C) in mid to late spring, there appears to be biological activity stimulating a diel signal for NO3 with maximum concentration corresponding to low light (11 PM). Investigating the primary

  9. Intermittent cranial lung herniation in two dogs.

    Science.gov (United States)

    Guglielmini, Carlo; De Simone, Antonio; Valbonetti, Luca; Diana, Alessia

    2007-01-01

    Two aged dogs with chronic obstructive airway disease were evaluated because of intermittent swelling of the ventral cervical region. Radiographs made at expiration and caudal positioning of the forelimbs allowed identification of intermittent cervical lung herniation of the left and right cranial lung lobe in both dogs. Pulmonary hyperinflation, increased expiratory effort, and chronic coughing were considered responsible for the lung herniation. Cervical lung hernia should be included in the differential diagnoses of intermittent cervical swelling in dogs with chronic respiratory disorders associated with increased expiratory effort and chronic coughing.

  10. Headwater Capture Evidenced by Paleo-Rivers Reconstruction and Population Genetic Structure of the Armored Catfish (Pareiorhaphis garbei) in the Serra do Mar Mountains of Southeastern Brazil

    Science.gov (United States)

    Lima, Sergio M. Q.; Berbel-Filho, Waldir M.; Araújo, Thais F. P.; Lazzarotto, Henrique; Tatarenkov, Andrey; Avise, John C.

    2017-01-01

    Paleo-drainage connections and headwater stream-captures are two main historical processes shaping the distribution of strictly freshwater fishes. Recently, bathymetric-based methods of paleo-drainage reconstruction have opened new possibilities to investigate how these processes have shaped the genetic structure of freshwater organisms. In this context, the present study used paleo-drainage reconstructions and single-locus cluster delimitation analyses to examine genetic structure on the whole distribution of Pareiorhaphis garbei, a ‘near threatened’ armored catfish from the Fluminense freshwater ecoregion in Southeastern Brazil. Sequences of two mitochondrial genes (cytochrome b and cytochrome c oxidase subunit 1) were obtained from five sampling sites in four coastal drainages: Macaé (KAE), São João (SJO), Guapi-Macacu [sub-basins Guapiaçu (GAC) and Guapimirim (GMI)], and Santo Aleixo (SAL). Pronounced genetic structure was found, involving 10 haplotypes for cytB and 6 for coi, with no haplotypes shared between localities. Coalescent-based delineation methods as well as distance-based methods revealed genetic clusters corresponding to each sample site. Paleo-drainage reconstructions showed two putative paleo-rivers: an eastern one connecting KAE and SJO; and a western one merging in the Guanabara Bay (GAC, GMI, and SAL). A disagreement was uncovered between the inferred past riverine connections and current population genetic structure. Although KAE and SJO belong to the same paleo-river, the latter is more closely related to specimens from the Guanabara paleo-river. This discordance between paleo-drainage connections and phylogenetic structure may indicate an ancient stream-capture event in headwaters of this region. Furthermore, all analyses showed high divergence between KAE and the other lineages, suggesting at least one cryptic species in the latter, and that the nominal species should be restricted to the Macaé river basin, its type locality. In

  11. Headwater Capture Evidenced by Paleo-Rivers Reconstruction and Population Genetic Structure of the Armored Catfish (Pareiorhaphis garbei in the Serra do Mar Mountains of Southeastern Brazil

    Directory of Open Access Journals (Sweden)

    Sergio M. Q. Lima

    2017-12-01

    Full Text Available Paleo-drainage connections and headwater stream-captures are two main historical processes shaping the distribution of strictly freshwater fishes. Recently, bathymetric-based methods of paleo-drainage reconstruction have opened new possibilities to investigate how these processes have shaped the genetic structure of freshwater organisms. In this context, the present study used paleo-drainage reconstructions and single-locus cluster delimitation analyses to examine genetic structure on the whole distribution of Pareiorhaphis garbei, a ‘near threatened’ armored catfish from the Fluminense freshwater ecoregion in Southeastern Brazil. Sequences of two mitochondrial genes (cytochrome b and cytochrome c oxidase subunit 1 were obtained from five sampling sites in four coastal drainages: Macaé (KAE, São João (SJO, Guapi-Macacu [sub-basins Guapiaçu (GAC and Guapimirim (GMI], and Santo Aleixo (SAL. Pronounced genetic structure was found, involving 10 haplotypes for cytB and 6 for coi, with no haplotypes shared between localities. Coalescent-based delineation methods as well as distance-based methods revealed genetic clusters corresponding to each sample site. Paleo-drainage reconstructions showed two putative paleo-rivers: an eastern one connecting KAE and SJO; and a western one merging in the Guanabara Bay (GAC, GMI, and SAL. A disagreement was uncovered between the inferred past riverine connections and current population genetic structure. Although KAE and SJO belong to the same paleo-river, the latter is more closely related to specimens from the Guanabara paleo-river. This discordance between paleo-drainage connections and phylogenetic structure may indicate an ancient stream-capture event in headwaters of this region. Furthermore, all analyses showed high divergence between KAE and the other lineages, suggesting at least one cryptic species in the latter, and that the nominal species should be restricted to the Macaé river basin, its type

  12. The role of the geophysical template and environmental regimes in controlling stream-living trout populations

    Science.gov (United States)

    Penaluna, Brooke E.; Railsback, Steve F.; Dunham, Jason B.; Johnson, S.; Bilby, Richard E.; Skaugset, Arne E.

    2015-01-01

    The importance of multiple processes and instream factors to aquatic biota has been explored extensively, but questions remain about how local spatiotemporal variability of aquatic biota is tied to environmental regimes and the geophysical template of streams. We used an individual-based trout model to explore the relative role of the geophysical template versus environmental regimes on biomass of trout (Oncorhynchus clarkii clarkii). We parameterized the model with observed data from each of the four headwater streams (their local geophysical template and environmental regime) and then ran 12 simulations where we replaced environmental regimes (stream temperature, flow, turbidity) of a given stream with values from each neighboring stream while keeping the geophysical template fixed. We also performed single-parameter sensitivity analyses on the model results from each of the four streams. Although our modeled findings show that trout biomass is most responsive to changes in the geophysical template of streams, they also reveal that biomass is restricted by available habitat during seasonal low flow, which is a product of both the stream’s geophysical template and flow regime. Our modeled results suggest that differences in the geophysical template among streams render trout more or less sensitive to environmental change, emphasizing the importance of local fish–habitat relationships in streams.

  13. Intermittent sea-level acceleration

    Science.gov (United States)

    Olivieri, M.; Spada, G.

    2013-10-01

    Using instrumental observations from the Permanent Service for Mean Sea Level (PSMSL), we provide a new assessment of the global sea-level acceleration for the last ~ 2 centuries (1820-2010). Our results, obtained by a stack of tide gauge time series, confirm the existence of a global sea-level acceleration (GSLA) and, coherently with independent assessments so far, they point to a value close to 0.01 mm/yr2. However, differently from previous studies, we discuss how change points or abrupt inflections in individual sea-level time series have contributed to the GSLA. Our analysis, based on methods borrowed from econometrics, suggests the existence of two distinct driving mechanisms for the GSLA, both involving a minority of tide gauges globally. The first effectively implies a gradual increase in the rate of sea-level rise at individual tide gauges, while the second is manifest through a sequence of catastrophic variations of the sea-level trend. These occurred intermittently since the end of the 19th century and became more frequent during the last four decades.

  14. Social Smoking among Intermittent Smokers

    Science.gov (United States)

    Shiffman, Saul; Li, Xiaoxue; Dunbar, Michael S.; Ferguson, Stuart G.; Tindle, Hilary A.; Scholl, Sarah M.

    2015-01-01

    Background “Social smoking” - smoking mostly or even only with others – may be an important pattern that implies smoking motivated extrinsically by social influences. Non-daily smokers (intermittent smokers; ITS) are often assumed to be social smokers, with some authors even assuming that all ITS are social smokers (SS+). We sought to identify and characterize social smokers in a sample of ITS. Methods 204 adult ITS (smoking 4–27 days/month) recorded the circumstances of smoking in their natural settings using Ecological Momentary Assessment, while also recording their circumstances in nonsmoking moments. SS+ were defined as ITS who were with others when they smoked most of their cigarettes, and who were ≥ 50% more likely to be with others when smoking than when not. Results Only 13% of ITS were SS+. Although defined solely on the basis of presence of others, SS+ showed a distinct pattern of smoking across multiple dimensions: Compared to other ITS (who were significantly less likely to smoke when with others), SS+ smoking was more associated with socializing, being with friends and acquaintances, drinking alcohol, weekends, evening or nighttime, being in other people’s homes, but not their own home. SS+ smoking was low in the morning and increased in the evening. SS+ smoked fewer days/week and were less dependent, but did not differ demographically. Conclusions Social smoking does constitute a highly distinct smoking pattern, but is not common among adult ITS. PMID:26205313

  15. Intermittent ileocoecal intususception in adult

    International Nuclear Information System (INIS)

    Cambal, M.; Zonca, P.; Maly, T.

    2013-01-01

    Aim: Aim of our paper is to present a case-report of chronic invagination in adult patient. Material: 28-years old woman with one year history of intermittent abdominal pain with symptoms of subileus state. She has underwent abdominal ultrasonography, abdominal X-ray, colonoscopy, irigography and abdominal CT. Appendectomy indicated for diagnosis of chronic appendicitis did not improve symptoms. Consecutively during acute problems were irigography and CT performed and diagnosis of an incomplete colon transversum obstruction of uncertain origin was established. There was stated suspicion of an intususception and patient was due to a repeated gastrointestinal passage indicated for an explorative laparotomy. During operation there was identified threefold invagination – colo-colonic, ileo-colonic and ileo-ileal. As a leading point of invagination was found in terminal ileum intraluminal polypous tumor 5 cm in diameter. Because of the secondary chronic changes of right colon wall and terminal ileum wall, after partial desinvagination right hemicolectomy was performed. Results: Patient was primary healed and now is without any subjective problems. Conclusion: Invagination is an acute abdominal event of obturative-strangulative type and it mainly occurs in infantile age. It is astonishing how long were patient´s difficulties lasting without obvious acute ileus. It is necessary in clinical practice to think on these rare reasons of gastrointestinal passage disorders. (author)

  16. White adipose tissue coloring by intermittent fasting.

    Science.gov (United States)

    Kivelä, Riikka; Alitalo, Kari

    2017-11-01

    Intermittent fasting (IF) has been shown to promote metabolic health in several organisms. Two recent papers show that IF induces white adipose tissue beiging and increases thermogenesis, which improves metabolic health in mice.

  17. On-line intermittent connector anomaly detection

    Data.gov (United States)

    National Aeronautics and Space Administration — This paper investigates a non-traditional use of differential current sensor and current sensor to detect intermittent disconnection problems in connectors. An...

  18. Intermittent chaotic chimeras for coupled rotators

    DEFF Research Database (Denmark)

    Olmi, Simona; Martens, Erik Andreas; Thutupalli, Shashi

    2015-01-01

    Two symmetrically coupled populations of N oscillators with inertia m display chaotic solutions with broken symmetry similar to experimental observations with mechanical pendulums. In particular, we report evidence of intermittent chaotic chimeras, where one population is synchronized and the other...

  19. Feigenbaum attractor and intermittency in particle collisions

    International Nuclear Information System (INIS)

    Batunin, A.V.

    1992-01-01

    The hypothesis is proposed that the Feigenbaum attractor arising as a limit set in an infinite pichfork bifurcation sequence for unimodal one-dimensional maps underlies the intermittency phenomena in particle collisions. 23 refs.; 8 figs

  20. Runoff Responses to Forest Thinning at Plot and Catchment Scales in a Headwater Catchment Draining Japanese Cypress Forest

    Science.gov (United States)

    We examined the effect of forest thinning on runoff generation at plot and catchment scales in headwater basins draining a Japanese cypress (Chamaecyparis obtusa) forest. We removed 58.3% of the stems (corresponding to 43.2% of the basal area) in the treated headwater basin (catc...

  1. Mississippi River Headwaters Lakes in Minnesota. Feasibility Study. Appendices.

    Science.gov (United States)

    1982-09-01

    organisms by blanketing stream or lake bottoms, spawning beds, or other desirable bottom area. Suspended solids may kill fish and shellfish by causing...Tree S~rv Long-billed M~arsh Wren 0Ctlipping S;-arrcd Short-billed Marsh Wren N Clay-crod )rm: Mockingbird L. Field Sparrow Gray Catbird VH;;rris

  2. Controls of event-based nutrient transport within nested headwater agricultural watersheds of the western Lake Erie basin

    Science.gov (United States)

    Williams, Mark R.; Livingston, Stanley J.; Penn, Chad J.; Smith, Douglas R.; King, Kevin W.; Huang, Chi-hua

    2018-04-01

    Understanding the processes controlling nutrient delivery in headwater agricultural watersheds is essential for predicting and mitigating eutrophication and harmful algal blooms in receiving surface waters. The objective of this study was to elucidate nutrient transport pathways and examine key components driving nutrient delivery processes during storm events in four nested agricultural watersheds (298-19,341 ha) in the western Lake Erie basin with poorly drained soils and an extensive artificial drainage network typical of the Midwestern U.S. Concentration-discharge hysteresis patterns of nitrate-nitrogen (NO3-N), dissolved reactive phosphorus (DRP), and particulate phosphorus (PP) occurring during 47 storm events over a 6 year period (2004-2009) were evaluated. An assessment of the factors producing nutrient hysteresis was completed following a factor analysis on a suite of measured environmental variables representing the fluvial and wider watershed conditions prior to, and during the monitored storm events. Results showed the artificial drainage network (i.e., surface tile inlets and subsurface tile drains) in these watersheds was the primary flow pathway for nutrient delivery to streams, but nutrient behavior and export during storm events was regulated by the flow paths to and the intensity of the drainage network, the availability of nutrients, and the relative contributions of upland and in-stream nutrient sources. Potential sources and flow pathways for transport varied among NO3-N, PP, and DRP with results underscoring the challenge of mitigating nutrient loss in these watersheds. Conservation practices addressing both nutrient management and hydrologic connectivity will likely be required to decrease nutrient loss in artificially drained landscapes.

  3. Changing climate and nutrient transfers: Evidence from high temporal resolution concentration-flow dynamics in headwater catchments.

    Science.gov (United States)

    Ockenden, M C; Deasy, C E; Benskin, C McW H; Beven, K J; Burke, S; Collins, A L; Evans, R; Falloon, P D; Forber, K J; Hiscock, K M; Hollaway, M J; Kahana, R; Macleod, C J A; Reaney, S M; Snell, M A; Villamizar, M L; Wearing, C; Withers, P J A; Zhou, J G; Haygarth, P M

    2016-04-01

    We hypothesise that climate change, together with intensive agricultural systems, will increase the transfer of pollutants from land to water and impact on stream health. This study builds, for the first time, an integrated assessment of nutrient transfers, bringing together a) high-frequency data from the outlets of two surface water-dominated, headwater (~10km(2)) agricultural catchments, b) event-by-event analysis of nutrient transfers, c) concentration duration curves for comparison with EU Water Framework Directive water quality targets, d) event analysis of location-specific, sub-daily rainfall projections (UKCP, 2009), and e) a linear model relating storm rainfall to phosphorus load. These components, in combination, bring innovation and new insight into the estimation of future phosphorus transfers, which was not available from individual components. The data demonstrated two features of particular concern for climate change impacts. Firstly, the bulk of the suspended sediment and total phosphorus (TP) load (greater than 90% and 80% respectively) was transferred during the highest discharge events. The linear model of rainfall-driven TP transfers estimated that, with the projected increase in winter rainfall (+8% to +17% in the catchments by 2050s), annual event loads might increase by around 9% on average, if agricultural practices remain unchanged. Secondly, events following dry periods of several weeks, particularly in summer, were responsible for high concentrations of phosphorus, but relatively low loads. The high concentrations, associated with low flow, could become more frequent or last longer in the future, with a corresponding increase in the length of time that threshold concentrations (e.g. for water quality status) are exceeded. The results suggest that in order to build resilience in stream health and help mitigate potential increases in diffuse agricultural water pollution due to climate change, land management practices should target

  4. Floodplains as a source of fine sediment in grazed landscapes: tracing the source of suspended sediment in the headwaters of an intensively managed agricultural landscape

    Science.gov (United States)

    Yu, M.; Rhoads, B. L.; Stumpf, A.

    2017-12-01

    The flux of fine sediment within agricultural watersheds is an important factor determining the environmental quality of streams and rivers. Despite this importance, the contributions of sediment sources to suspended sediment loads within intensively managed agricultural watersheds remain poorly understood. This study assesses the provenance of fine suspended sediment in the headwater portion of a river flowing through an agricultural landscape in Illinois. Sediment source samples were collected from five potential sources: streambanks, forested floodplain, grassland, and grazed floodplains. Event-based and aggregated suspended sediment samples were collected from the stream at the watershed outlet. Quantitative geochemical fingerprinting techniques and a mixing model were employed to estimate the relative contributions of sediment from five potential sources to the suspended sediment loads. Organic matter content, trace elements, and fallout radionuclides were used as potential tracers. Principal Component analysis was employed to complement the results and Monte Carlo random sampling routine was used to test the uncertainty in estimated contributions of sources to in-stream sediment loads. Results indicate that the majority of suspended sediment is derived from streambanks and grazed floodplains. Erosion of the floodplain both by surface runoff and by streambank erosion from lateral channel migration contributes to the production of fine sediment within the stream system. These results suggest that human activities, in this case grazing, have converted portions of floodplains, normally net depositional environments, into sources of fine sediments. Efforts to reduce fluxes of fine sediment in this intensively managed landscape should focus on degraded floodplain surfaces and eroding channel banks within heavily grazed reaches of the stream.

  5. The Morphology of Streams Restored for Market and Nonmarket Purposes: Insights From a Mixed Natural-Social Science Approach

    Science.gov (United States)

    Singh, J.; Doyle, M.; Lave, R.; Robertson, M.

    2015-12-01

    Stream restoration is increasingly driven by compensatory mitigation; impacts to streams associated with typical land development activities must be offset via restoration of streams elsewhere. This policy creates an environment where restored stream 'credits' are traded under market-like conditions, comparable to wetland mitigation, carbon offsets, or endangered species habitat banking. The effect of mitigation on restoration design and construction is unknown. We use geomorphic surveys to quantify the differences between restored and nonrestored streams, and the difference between streams restored for market purposes (compensatory mitigation) from those restored for nonmarket programs. Physical study sites are located in the state of North Carolina, USA. We also analyze the social and political-economic drivers of the stream restoration and mitigation industry using analysis of policy documents and interviews with key personnel including regulators, mitigation bankers, stream designers, and scientists. Restored streams are typically wider, shallower and geomorphically more homogeneous than nonrestored streams. For example, nonrestored streams are typically characterized by more than an order of magnitude variability in radius of curvature and meander wavelength within a single study reach. By contrast, the radius of curvature in many restored streams does not vary for nearly the entire project reach. Streams restored for the mitigation market are typically headwater streams and part of a large, complex of long restored main channels, and many restored tributaries; streams restored for nonmarket purposes are typically shorter and consist of the main channel only. Interviews reveal that social forces shape the morphology of restored streams. Designers integrate many influences including economic and regulatory constraints, but traditions of practice have a large influence as well. Home to a fairly mature stream mitigation banking market, North Carolina can provide

  6. Get In and Get Out: Assessing Stream Sediment Loading from Short Duration Forest Harvest Operations and Rapid Haul Road Decommissioning.

    Science.gov (United States)

    Corrigan, A.; Silins, U.; Stone, M.

    2016-12-01

    Best management practices (BMPs) and associated erosion control measures for mitigating sediment impacts from forestry roads and road-stream crossings are well documented. While rapid road decommissioning after forestry operations may serve to limit broader impacts on sediment production in high value headwater streams, few studies have evaluated the combined effects of accelerated harvest operations and rapid retirement of logging roads and road-stream crossings on stream sediment. The objectives of this study were to evaluate the initial impacts of these strategies on fine sediment loading and fate during a short duration harvesting operation in 3 headwater sub-catchments in the southwestern Rocky Mountains of Alberta, Canada. A multi-pronged sampling approach (ISCOs, event focused grab sampling, continuous wash load sampling, and stream bed sediment intrusion measurements) was used to measure sediment loading and deposition in streambeds upstream and downstream of road-stream bridge crossings during harvest operations (2015) and after road and bridge crossing retirement (2016). Sediment production from forestry roads was generally much lower than has been reported from other studies in similar settings. Average total suspended solids (TSS) downstream of the bridge crossings were actually lower (-3.28 g/L; -0.704 g/L) than upstream of two bridge crossings while in-stream sediment sources contributed to elevated sediment downstream of a third road-stream crossing. Minimal in stream sediment impacts from forest harvest and road-stream crossings was likely a reflection of combined factors including a) employment of erosion control BMPs to roads and bridge crossings, b) rapid decommissioning of roads and crossings to limit exposure of linear land disturbance features, and c) drier El Niño climatic conditions during the study.

  7. Distribution patterns of fish assemblages in an Eastern Mediterranean intermittent river

    Directory of Open Access Journals (Sweden)

    Vardakas L.

    2015-01-01

    Full Text Available The distribution patterns of fish assemblages within streams can provide insights for river type classifications and may warrant specific conservation actions. However, there is limited knowledge of how fish assemblages assort along a longitudinal axis in Mediterranean intermittent streams. Patterns in spatial and temporal distribution of fish communities were analysed in a Mediterranean intermittent river (Evrotas River located in Southern Greece, hosting three endemic range restricted species of high conservation concern, during the period 2007−2009, with 80% of the river’s total length desiccating in the 2007 and 2008 droughts. The general trend was an increase in fish density and species richness along an upstream-downstream gradient. Fish assemblages from upstream to downstream were characterized by a decrease of the most rheophilic species (Squalius keadicus and an increase of the most stagnophilic species (Tropidophoxinellus spartiaticus. Three river segments, characterized by a high degree of homogeneity were delineated. Habitat and environmental preferences for the studied fish species were identified, with elevation and low flowing habitats being the most important environmental factors affecting fish distribution patterns. The current study provides evidence that even in an intermittent river an assemblage pattern following a longitudinal gradient can be identified, mainly due to the lack of instream barriers that allows recolonization after flow resumption.

  8. Using Video to Communicate Scientific Findings -- Habitat Connections in Urban Streams

    Science.gov (United States)

    Harned, D. A.; Moorman, M.; Fitzpatrick, F. A.; McMahon, G.

    2011-12-01

    The U.S Geological Survey (USGS) National Water-Quality Assessment Program (NAWQA) provides information about (1) water-quality conditions and how those conditions vary locally, regionally, and nationally, (2) water-quality trends, and (3) factors that affect those conditions. As part of the NAWQA Program, the Effects of Urbanization on Stream Ecosystems (EUSE) study examined the vulnerability and resilience of streams to urbanization. Completion of the EUSE study has resulted in over 20 scientific publications. Video podcasts are being used in addition to these publications to communicate the relevance of these scientific findings to more general audiences such as resource managers, educational groups, public officials, and the general public. An example of one of the podcasts is a film examining effects of urbanization on stream habitat. "Habitat Connections in Urban Streams" explores how urbanization changes some of the physical features that provide in-stream habitat and examines examples of stream restoration projects designed to improve stream form and function. The "connections" theme is emphasized, including the connection of in-stream habitats from the headwaters to the stream mouth; connections between stream habitat and the surrounding floodplains, wetlands and basin; and connections between streams and people-- resource managers, public officials, scientists, and the general public. Examples of innovative stream restoration projects in Baltimore Maryland; Milwaukee, Wisconsin; and Portland Oregon are shown with interviews of managers, engineers, scientists, and others describing the projects. The film is combined with a website with links to extended film versions of the stream-restoration project interviews. The website and films are an example of USGS efforts aimed at improving science communication to a general audience. The film is available for access from the EUSE website: http://water.usgs.gov/nawqa/urban/html/podcasts.html. Additional films are

  9. Nitrous oxide emission from denitrification in stream and river networks

    Science.gov (United States)

    Beaulieu, J.J.; Tank, J.L.; Hamilton, S.K.; Wollheim, W.M.; Hall, R.O.; Mulholland, P.J.; Peterson, B.J.; Ashkenas, L.R.; Cooper, L.W.; Dahm, Clifford N.; Dodds, W.K.; Grimm, N. B.; Johnson, S.L.; McDowell, W.H.; Poole, G.C.; Maurice, Valett H.; Arango, C.P.; Bernot, M.J.; Burgin, A.J.; Crenshaw, C.L.; Helton, A.M.; Johnson, L.T.; O'Brien, J. M.; Potter, J.D.; Sheibley, R.W.; Sobota, D.J.; Thomas, S.M.

    2011-01-01

    Nitrous oxide (N2O) is a potent greenhouse gas that contributes to climate change and stratospheric ozone destruction. Anthropogenic nitrogen (N) loading to river networks is a potentially important source of N 2O via microbial denitrification that converts N to N2O and dinitrogen (N2). The fraction of denitrified N that escapes as N2O rather than N2 (i.e., the N2O yield) is an important determinant of how much N2O is produced by river networks, but little is known about the N2O yield in flowing waters. Here, we present the results of whole-stream 15N-tracer additions conducted in 72 headwater streams draining multiple land-use types across the United States. We found that stream denitrification produces N2O at rates that increase with stream water nitrate (NO3-) concentrations, but that production, but does not increase the N2O yield. In our study, most streams were sources of N2O to the atmosphere and the highest emission rates were observed in streams draining urban basins. Using a global river network model, we estimate that microbial N transformations (e.g., denitrification and nitrification) convert at least 0.68 Tg??y -1 of anthropogenic N inputs to N2O in river networks, equivalent to 10% of the global anthropogenic N2O emission rate. This estimate of stream and river N2O emissions is three times greater than estimated by the Intergovernmental Panel on Climate Change.

  10. The response of macroinvertebrates to artificially enhanced detritus levels in plantation streams

    Science.gov (United States)

    Pretty, J. L.; Dobson, M.

    The leaves and wood from vegetation surrounding headwater streams constitute a major food source for aquatic invertebrates, providing they are retained upon the streambed and not transported downstream. This study investigated the response of aquatic invertebrates to artificially increased detritus retention, in an effort to reproduce the naturally occurring build up of dead organic matter associated with streams in old-growth forest. The background detrital standing stock in streams in Kielder Forest (Northumberland, UK) was low, approximately 32 gm-2. Two streams flowing through dense conifer plantation and one in open broadleaved woodland were manipulated by the addition of logs over a 10 m stream reach. After several months, log addition significantly enhanced detrital standing stocks in both conifer and broadleaved streams. Total invertebrate abundance, taxon richness and the numbers of certain numerically dominant families were significantly higher in experimental than reference reaches in both conifer and broadleaved streams. This response was most marked for detritivores, whilst non-detritivore groups often showed no response to the manipulation. Whilst in the short term the responses to enhanced retention may reflect a redistribution of the local fauna, it is argued that over a longer time-scale, a genuine increase in invertebrate density and diversity could occur. Allowing old-growth forest to develop in planted valley bottoms may be a viable management option for conservation. If established alongside streams, it would ensure continuous input of woody material and the fauna may benefit from the resulting increase in detritus retention.

  11. How do land-based salmonid farms affect stream ecology?

    International Nuclear Information System (INIS)

    Tello, A.; Corner, R.A.; Telfer, T.C.

    2010-01-01

    Increasing research is highlighting the fact that streams provide crucial ecosystem services through the biogeochemical and ecological processes they sustain. Freshwater land-based salmonid farms commonly discharge their effluents into low order, headwater streams, partly due to the fact that adequate freshwater resources for production are commonly found in undisturbed areas. We review the effects of salmonid farm effluents on different biological components of stream ecosystems. Relevant considerations related to the temporal and spatial scales of effluent discharge and ecological effects are discussed. These highlight the need to characterize the patterns of stressor discharge when assessing environmental impacts and designing ecological effects studies. The potential role of multiple stressors in disrupting ecosystem structure and function is discussed with an emphasis on aquaculture veterinary medicines. Further research on the effects of veterinary medicines using relevant exposure scenarios would significantly contribute to our understanding of their impact in relation to other effluent stressors. - This article reviews the effects of aquaculture effluents on stream ecosystems with an emphasis on veterinary medicines and the temporal patterns of effluent discharge.

  12. Intermittent ephemeral river-breaching

    Science.gov (United States)

    Reniers, A. J.; MacMahan, J. H.; Gallagher, E. L.; Shanks, A.; Morgan, S.; Jarvis, M.; Thornton, E. B.; Brown, J.; Fujimura, A.

    2012-12-01

    In the summer of 2011 we performed a field experiment in Carmel River State Beach, CA, at a time when the intermittent natural breaching of the ephemeral Carmel River occurred due to an unusually rainy period prior to the experiment associated with El Nino. At this time the river would fill the lagoon over the period of a number of days after which a breach would occur. This allowed us to document a number of breaches with unique pre- and post-breach topographic surveys, accompanying ocean and lagoon water elevations as well as extremely high flow (4m/s) velocities in the river mouth during the breaching event. The topographic surveys were obtained with a GPS-equipped backpack mounted on a walking human and show the evolution of the river breaching with a gradually widening and deepening river channel that cuts through the pre-existing beach and berm. The beach face is qualified as a steep with an average beach slope of 1:10 with significant reflection of the incident waves (MacMahan et al., 2012). The wave directions are generally shore normal as the waves refract over the deep canyon that is located offshore of the beach. The tide is mixed semi-diurnal with a range on the order of one meter. Breaching typically occurred during the low-low tide. Grain size is highly variable along the beach with layers of alternating fine and coarse material that could clearly be observed as the river exit channel was cutting through the beach. Large rocky outcroppings buried under the beach sand are also present along certain stretches of the beach controlling the depth of the breaching channel. The changes in the water level measured within the lagoon and the ocean side allows for an estimate of the volume flux associated with the breach as function of morphology, tidal elevation and wave conditions as well as an assessment of the conditions and mechanisms of breach closure, which occurred on the time scale of O(0.5 days). Exploratory model simulations will be presented at the

  13. Coherent Structures and Intermittency in Plasma Turbulence

    International Nuclear Information System (INIS)

    Das, Amita; Kaw, Predhiman; Sen, Abhijit

    2008-01-01

    The paper discusses some fundamental issues related to the phenomenon of intermittency in plasma turbulence with particular reference to experimental observations in fusion devices. Intermittency is typically associated with the presence of coherent structures in turbulence. Since coherent structures can play an important role in governing the transport properties of a system they have received a great deal of attention in fusion research. We review some of the experimental measurements and numerical simulation studies on the presence and formation of coherent structures in plasmas and discuss their relevance to intermittency. Intermittency, as widely discussed in the context of neutral fluid turbulence, implies multiscaling behaviour in contrast to self-similar scaling patterns observed in self organized criticality (SOC) phenomenon. The experimental evidence from plasma turbulence measurements reveal a mixed picture--while some observations support the SOC model description others indicate the presence of multiscaling behaviour. We discuss these results in the light of our present understanding of plasma turbulence and in terms of certain unique aspects of intermittency as revealed by fluid models of plasmas.

  14. Intermittency in {sup 197}Au fragmentation

    Energy Technology Data Exchange (ETDEWEB)

    Dabrowska, A; Holynski, R; Olszewski, A; Szarska, M; Wilczynska, B; Wolter, W; Wosiek, B [Institute of Nuclear Physics, Cracow (Poland); Cherry, M L; Deines-Jones, P; Jones, W V; Sengupta, K; Wefel, B [Louisiana State Univ., Baton Rouge, LA (United States). Dept. of Physics and Astronomy; Waddington, C J [Minnesota Univ., Minneapolis, MN (United States). School of Physics and Astronomy; Pozharova, E A; Skorodko, T Yu [Inst. of Theoretical and Experimental Physics, Moscow (Russian Federation); KLMM Collaboration

    1995-07-01

    The concept of factorial moments was applied to an analysis of the dynamical fluctuations in the charge distributions of the fragments emitted from gold nuclei with energies 10.6 and < 1.0 GeV/n interacting with emulsion nuclei. Clear evidence for intermittent fluctuations has been found in an analysis using all the particles released from the gold projectile, with a stronger effect observed below 1 GeV/n than at 10.6 GeV/n. For the full data sets, however, the intermittency effect was found to be very sensitive to the singly charged particles, and neglecting these particles strongly reduces the intermittency signal. When the analysis is restricted to the multiply charged fragments, an intermittency effect is revealed only for multifragmentation events, although one that is enhanced as compared to the analysis of all, singly and multiply charged, particles. The properties of the anomalous fractal dimensions suggest a sequential decay mechanism, rather than the existence of possible critical behaviour in the process of nuclear fragmentation. The likely influence of the charge conservation effects and the finite size of decaying systems on the observed intermittency signals was pointed out. (author). 37 refs, 9 figs, 5 tabs.

  15. Persistent effects of wildfire and debris flows on the invertebrate prey base of rainbow trout in Idaho streams

    Science.gov (United States)

    Rosenberger, A.E.; Dunham, J.B.; Buffington, J.M.; Wipfli, M.S.

    2011-01-01

    Wildfire and debris flows are important physical and ecological drivers in headwater streams of western North America. Past research has primarily examined short-term effects of these disturbances; less is known about longer-term impacts. We investigated wildfire effects on the invertebrate prey base for drift-feeding rainbow trout (Oncorhynchus mykiss, Walbaum) in Idaho headwater streams a decade after wildfire. Three stream types with different disturbance histories were examined: 1) unburned, 2) burned, and 3) burned followed by debris flows that reset channel morphology and riparian vegetation. The quantity of macroinvertebrate drift (biomass density) was more variable within than among disturbance categories. Average body weight and taxonomic richness of drift were significantly related to water temperature and influenced by disturbance history. During the autumn sampling period, the amount of terrestrial insects in rainbow trout diets varied with disturbance history and the amount of overhead canopy along the stream banks. Results indicate that there are detectable changes to macroinvertebrate drift and trout diet a decade after wildfire, and that these responses are better correlated with specific characteristics of the stream (water temperature, canopy cover) than with broad disturbance classes.

  16. Future and recent changes in flow patterns in the Czech headwater catchments

    Czech Academy of Sciences Publication Activity Database

    Benčoková, A.; Hruška, Jakub; Krám, P.; Stuchlik, E.

    2011-01-01

    Roč. 62, 1-4 (2011), s. 17-22 ISSN 0006-5471 R&D Projects: GA MŠk(CZ) ED1.1.00/02.0073 Institutional research plan: CEZ:AV0Z60870520 Keywords : Headwater catchments * hydrological modelling * regional climate model Subject RIV: EH - Ecology, Behaviour

  17. An inexpensive and portable drill rig for bedrock groundwater studies in headwater catchments

    Science.gov (United States)

    C. Gabrielli; J.J. McDonnell

    2011-01-01

    Bedrock groundwater dynamics in headwater catchments are poorly understood and poorly characterized. Here, we present an inexpensive and portable bedrock drilling system designed for use in remote locations. Our system is capable of drilling bedrock wells up to 11 m deep and 38 mm in diameter in a wide range of bedrock types. The drill consists of a lawn mower engine...

  18. 77 FR 22606 - Proposed Information Collection; Visitor Use Surveys for Headwaters Forest Reserve and King Range...

    Science.gov (United States)

    2012-04-16

    ... visitor use surveys would assist the BLM in meeting goals set forth in Resource Management Plans (RMPs... DEPARTMENT OF THE INTERIOR Bureau of Land Management [LLCAN03900 L17110000 AL0000] Proposed Information Collection; Visitor Use Surveys for Headwaters Forest Reserve and King Range National Conservation...

  19. Riparian buffer and density management influences on microclimate of young headwater forests of Western Oregon.

    Science.gov (United States)

    Paul D. Anderson; David J. Larson; Samuel S. Chan

    2007-01-01

    Thinning of 30- to 70-year-old Douglas-fir (Psuedotsuga menziesii [Mirb.] Franco) stands is a common silvicultural activity on federal forest lands of the Pacific Northwest, United States. Empirical relationships among riparian functions, silvicultural treatments, and different riparian buffer widths are not well documented for small headwater...

  20. Stream network responses to evapotranspiration in mountain systems: evidence from spatially-distributed network mapping and sapflow measurements

    Science.gov (United States)

    Godsey, S.; Whiting, J. A.; Reinhardt, K.

    2015-12-01

    Stream networks respond to decreased inputs by shrinking from their headwaters and disconnecting along their length. Both the relative stability of the stream network and the degree of disconnection along the network length can strongly affect stream ecology, including fish migration and nutrient spiraling. Previous data suggests that stream network lengths decrease measurably as discharge decreases, and that evapotranspiration may be an important control on stream network persistence. We hypothesized that changes in sapflow timing and magnitude across a gradient from rain-dominated to snow-dominated elevations would be reflected in the stability of the stream network in a steep watershed draining to the Middle Fork Salmon in central Idaho. We expected that the relative timing of water availability across the gradient would drive differences in water delivery to both trees and the stream network. Here we present results that highlight the stability of sapflow timing across the gradient and persistence of the stream network at this site. We discuss geologic controls on network stability and present a conceptual framework identifying characteristics of stable flowheads. We test this framework at four sites in central Idaho with mapped stream networks. We also discuss late summer sapflow patterns across the elevation gradient and their linkages to soil and atmospheric characteristics. Finally, we compare these patterns to those observed at other sites and discuss the role of vegetation in controlling spatiotemporal patterns across the stream network.

  1. Forces and energetics of intermittent swimming

    Science.gov (United States)

    Floryan, Daniel; Van Buren, Tyler; Smits, Alexander J.

    2017-08-01

    Experiments are reported on intermittent swimming motions. Water tunnel experiments on a nominally two-dimensional pitching foil show that the mean thrust and power scale linearly with the duty cycle, from a value of 0.2 all the way up to continuous motions, indicating that individual bursts of activity in intermittent motions are independent of each other. This conclusion is corroborated by particle image velocimetry (PIV) flow visualizations, which show that the main vortical structures in the wake do not change with duty cycle. The experimental data also demonstrate that intermittent motions are generally energetically advantageous over continuous motions. When metabolic energy losses are taken into account, this conclusion is maintained for metabolic power fractions less than 1.

  2. Chaos synchronization based on intermittent state observer

    Institute of Scientific and Technical Information of China (English)

    Li Guo-Hui; Zhou Shi-Ping; Xu De-Ming

    2004-01-01

    This paper describes the method of synchronizing slave to the master trajectory using an intermittent state observer by constructing a synchronizer which drives the response system globally tracing the driving system asymptotically. It has been shown from the theory of synchronization error-analysis that a satisfactory result of chaos synchronization is expected under an appropriate intermittent period and state observer. Compared with continuous control method,the proposed intermittent method can target the desired orbit more efficiently. The application of the method is demonstrated on the hyperchaotic Rossler systems. Numerical simulations show that the length of the synchronization interval rs is of crucial importance for our scheme, and the method is robust with respect to parameter mismatch.

  3. StreamCat

    Data.gov (United States)

    U.S. Environmental Protection Agency — The StreamCat Dataset provides summaries of natural and anthropogenic landscape features for ~2.65 million streams, and their associated catchments, within the...

  4. Prioritized Contact Transport Stream

    Science.gov (United States)

    Hunt, Walter Lee, Jr. (Inventor)

    2015-01-01

    A detection process, contact recognition process, classification process, and identification process are applied to raw sensor data to produce an identified contact record set containing one or more identified contact records. A prioritization process is applied to the identified contact record set to assign a contact priority to each contact record in the identified contact record set. Data are removed from the contact records in the identified contact record set based on the contact priorities assigned to those contact records. A first contact stream is produced from the resulting contact records. The first contact stream is streamed in a contact transport stream. The contact transport stream may include and stream additional contact streams. The contact transport stream may be varied dynamically over time based on parameters such as available bandwidth, contact priority, presence/absence of contacts, system state, and configuration parameters.

  5. Hydrologic controls on the export dynamics of dissolved and particulate phosphorus in a lowland, headwater agricultural catchment

    Science.gov (United States)

    Dupas, Rémi; Grimaldi, Catherine; Gruau, Gérard; Gascuel-Odoux, Chantal

    2014-05-01

    Phosphorus (P) availability controls eutrophication in freshwater ecosystems, since P is generally the limiting nutrient to algal development. The contribution of diffuse P emission to surface waters is significant in intensively livestock farmed catchments as a result of high application rates of P-rich animal waste and subsequent enrichment of soils. This study investigates the transport dynamics of particulate phosphorus (PP), suspended sediments (SS), and dissolved phosphorus (DP) with the aim of elucidating the relationship between PP and DP transport mechanisms and water dynamics in lowland, headwater catchments. The selected catchment (Kervidy-Naizin catchment, France) is particularly suitable for this purpose as it benefits of a 5 years, high-frequency monitoring of PP and DP concentrations at its outlet, including data recovered both during base flow and storm periods, with the monitoring of more than 50 storm flow events. The data analysis includes interpretation of concentration-discharge relationships at the annual time scale and on an event basis, seasonal analysis of flood characteristics and empirical modeling. Annual DP and PP concentration-discharge relationships of interflood samples display a hysteretic pattern, with higher concentrations during the autumn and spring periods, and progressive decrease during winter. No hysteretic pattern is visible for interflood SS concentration, which follows a classical C=a*Qb relationship. During floods, the dynamic of PP export is similar to that of SS during most of the events: the concentration peak occurs during the rising limb of the hydrogram (clockwise hysteresis), suggesting a source close to or within the stream. The amplitude and the hysteresis' loop size for SS and PP are a function of maximum discharge and rate of change in discharge. On the contrary, there is a strong decoupling between DP and SS (and thus PP) during most of the floods (no significant correlation), with DP concentration peaks

  6. Unsteady propulsion by an intermittent swimming gait

    Science.gov (United States)

    Akoz, Emre; Moored, Keith W.

    2018-01-01

    Inviscid computational results are presented on a self-propelled swimmer modeled as a virtual body combined with a two-dimensional hydrofoil pitching intermittently about its leading edge. Lighthill (1971) originally proposed that this burst-and-coast behavior can save fish energy during swimming by taking advantage of the viscous Bone-Lighthill boundary layer thinning mechanism. Here, an additional inviscid Garrick mechanism is discovered that allows swimmers to control the ratio of their added mass thrust-producing forces to their circulatory drag-inducing forces by decreasing their duty cycle, DC, of locomotion. This mechanism can save intermittent swimmers as much as 60% of the energy it takes to swim continuously at the same speed. The inviscid energy savings are shown to increase with increasing amplitude of motion, increase with decreasing Lighthill number, Li, and switch to an energetic cost above continuous swimming for sufficiently low DC. Intermittent swimmers are observed to shed four vortices per cycle that form into groups that are self-similar with the DC. In addition, previous thrust and power scaling laws of continuous self-propelled swimming are further generalized to include intermittent swimming. The key is that by averaging the thrust and power coefficients over only the bursting period then the intermittent problem can be transformed into a continuous one. Furthermore, the intermittent thrust and power scaling relations are extended to predict the mean speed and cost of transport of swimmers. By tuning a few coefficients with a handful of simulations these self-propelled relations can become predictive. In the current study, the mean speed and cost of transport are predicted to within 3% and 18% of their full-scale values by using these relations.

  7. Shape of power spectrum of intermittent chaos

    International Nuclear Information System (INIS)

    So, B.C.; Mori, H.

    1984-01-01

    Power spectra of intermittent chaos are calculated analytically. It is found that the power spectrum near onset point consists of a large number of Lorentzian lines with two peaks around frequencies ω = 0 and ω = ω 0 , where ω 0 is a fundamental frequency of a periodic orbit before the onset point, and furthermore the envelope of lines around ω = 0 obeys the power law 1/ + ω +2 , whereas the envelope around ω 0 obeys 1/ + ω-ω 0 +4 . The universality of these power law dependence in a certain class of intermittent chaos are clarified from a phenomenological view point. (author)

  8. Productivity of Stream Definitions

    NARCIS (Netherlands)

    Endrullis, Jörg; Grabmayer, Clemens; Hendriks, Dimitri; Isihara, Ariya; Klop, Jan

    2007-01-01

    We give an algorithm for deciding productivity of a large and natural class of recursive stream definitions. A stream definition is called ‘productive’ if it can be evaluated continuously in such a way that a uniquely determined stream is obtained as the limit. Whereas productivity is undecidable

  9. Productivity of stream definitions

    NARCIS (Netherlands)

    Endrullis, J.; Grabmayer, C.A.; Hendriks, D.; Isihara, A.; Klop, J.W.

    2008-01-01

    We give an algorithm for deciding productivity of a large and natural class of recursive stream definitions. A stream definition is called ‘productive’ if it can be evaluated continually in such a way that a uniquely determined stream in constructor normal form is obtained as the limit. Whereas

  10. Riparian zone controls on base cation concentrations in boreal streams

    Science.gov (United States)

    Ledesma, J. L. J.; Grabs, T.; Futter, M. N.; Bishop, K. H.; Laudon, H.; Köhler, S. J.

    2013-01-01

    Forest riparian zones are a major in control of surface water quality. Base cation (BC) concentrations, fluxes, and cycling in the riparian zone merit attention because of increasing concern of negative consequences for re-acidification of surface waters from future climate and forest harvesting scenarios. We present a two-year study of BC and silica (Si) flow-weighted concentrations from 13 riparian zones and 14 streams in a boreal catchment in northern Sweden. The Riparian Flow-Concentration Integration Model (RIM) was used to estimate riparian zone flow-weighted concentrations and tested to predict the stream flow-weighted concentrations. Spatial variation in BC and Si concentrations as well as in flow-weighted concentrations was related to differences in Quaternary deposits, with the largest contribution from lower lying silty sediments and the lowest contribution from wetland areas higher up in the catchment. Temporal stability in the concentrations of most elements, a remarkably stable Mg / Ca ratio in the soil water and a homogeneous mineralogy suggest that the stable patterns found in the riparian zones are a result of distinct mineralogical upslope groundwater signals integrating the chemical signals of biological and chemical weathering. Stream water Mg / Ca ratio indicates that the signal is subsequently maintained in the streams. RIM gave good predictions of Ca, Mg, and Na flow-weighted concentrations in headwater streams. The difficulty in modelling K and Si suggests a stronger biogeochemical influence on these elements. The observed chemical dilution effect with flow in the streams was related to variation in groundwater levels and element concentration profiles in the riparian zones. This study provides a first step toward specific investigations of the vulnerability of riparian zones to changes induced by forest management or climate change, with focus on BC or other compounds.

  11. Which factors make clean intermittent (self) catheterisation successful?

    NARCIS (Netherlands)

    Cobussen-Boekhorst, H.; Beekman, J.; Wijlick, E. van; Schaafstra, J.; Kuppevelt, D. van; Heesakkers, J.P.

    2016-01-01

    AIMS AND OBJECTIVES: To explore which factors determine successful intermittent catheterisation. BACKGROUND: Intermittent catheterisation is a safe, effective treatment and is associated with improved quality of life, although negative issues are reported. Factors which determine adherence are

  12. Fractal structures and intermittency in QCD

    International Nuclear Information System (INIS)

    Gustafson, Goesta.

    1990-04-01

    New results are presented for fractal structures and intermittency in QCD parton showers. A geometrical interpretation of the anomalous dimension in QCD is given. It is shown that model predications for factorial moments in the PEP-PETRA energy range are increased. if the properties of directly produced pions are more carefully taken into account

  13. Intermittent demand : Linking forecasting to inventory obsolescence

    NARCIS (Netherlands)

    Teunter, Ruud H.; Syntetos, Aris A.; Babai, M. Zied

    2011-01-01

    The standard method to forecast intermittent demand is that by Croston. This method is available in ERP-type solutions such as SAP and specialised forecasting software packages (e.g. Forecast Pro), and often applied in practice. It uses exponential smoothing to separately update the estimated demand

  14. Acute intermittent porphyria presenting as progressive muscular ...

    African Journals Online (AJOL)

    Acute intermittent porphyria, the most common porphyria affecting the nervous system, typically presents with neurovisceral crises followed by a motor neuropathy. We describe a 23-year-old black South African man presenting with a progressive stuttering, lower motor neuron syndrome developing over months. He had not ...

  15. Cooling tower modification for intermittent operation

    International Nuclear Information System (INIS)

    Midkiff, W.S.

    1975-03-01

    One of the cooling towers at Los Alamos Scientific Laboratory is being operated intermittently. The cooling tower has been modified to restrict air flow and to keep the tower from drying out. The modifications are relatively inexpensive, simple to operate, and have proved effective. (U.S.)

  16. Intermittent preventive treatment of malaria in pregnancy

    DEFF Research Database (Denmark)

    Mbonye, A.K.; Hansen, Kristian Schultz; Bygbjerg, Ib Christian

    2008-01-01

    The main objective of this study was to assess whether traditional birth attendants, drug-shop vendors, community reproductive health workers and adolescent peer mobilisers could administer intermittent preventive treatment (IPTp) with sulfadoxine-pyrimethamine (SP) to pregnant women. The study w...

  17. Management of patients with intermittent claudication

    NARCIS (Netherlands)

    S. Spronk (Sandra)

    2008-01-01

    textabstractIntermittent claudication is the first and mildest manifestation of peripheral arterial disease, caused by the atherosclerotic process of progressive narrowing of one or more of the arteries of the peripheral circulation.1 If the arterial system fails, it results in a progressive oxygen

  18. Intermittent resistive faults in digital cmos circuits

    NARCIS (Netherlands)

    Kerkhoff, Hans G.; Ebrahimi, Hassan

    2015-01-01

    A major threat in extremely dependable high-end process node integrated systems in e.g. Avionics are no failures found (NFF). One category of NFFs is the intermittent resistive fault, often originating from bad (e.g. Via or TSV-based) interconnections. This paper will show the impact of these faults

  19. Intermittent and global transitions in plasma turbulence

    International Nuclear Information System (INIS)

    Vlad, M.; Spineanu, F.; Itoh, K.; Itoh, S.-I.

    2003-07-01

    The dynamics of the transition processes in plasma turbulence described by the nonlinear Langevin equation (1) is studied. We show that intermittent or global transitions between metastable states can appear. The conditions for the generation of these transitions and their statistical characteristics are determined. (author)

  20. The hydrochemistry of the headwaters of the River Severn, Plynlimon

    Directory of Open Access Journals (Sweden)

    C. Neal

    1997-01-01

    Full Text Available Water quality data spanning 13 years and covering an extensive range of major, minor and trace elements in rain and stream waters at Plynlimon in mid Wales, are presented. Rainfall water chemistry is highly variable due to varying proportions of marine and pollutant derived constituents associated with patterns of atmospheric circulation. Stream waters, being composed of different proportions of waters from three chemically distinct sources at any one time (atmospheric deposition, the soil system and deeper groundwaters, are also chemically highly variable. For example, components predominantly derived from deposition such as chloride change only in response to sea-salt deposition episodes. Solutes associated with bedrock weathering such as calcium, magnesium, and alkalinity decrease with increasing flow, those associated with the upper soil layers such as aluminium, many transition metals, dissolved organic carbon and hydrogen ions increase with increasing flow. The nutrients (e.g. nitrate, boron, bromide and iodine exhibit strong seasonal cycles associated with cycles of vegetation growth and decay. The changes in stream water chemistry resulting from tree harvesting in the Afon Hore catchment are shown to have run their course within a period of eight years. Nutrient increases in the first few years following the commencement of felling have returned to or fallen below pre-felling values. Aluminium changes are shown to be complicated by changes in nitrate and calcium. Aluminium concentrations initially increased and have fallen below their pre-felling value. Data for chloride suggest a reduction in capture of dry and mist deposition; this indicates the importance of understanding reduced deposition as a result of felling. Felling has also affected the soil micro-climate which experiences greater fluctuations in temperature and an increase in the concentration of constituents associated with organic matter. Input-output mass balance estimates

  1. The suitability of using dissolved gases to determine groundwater discharge to high gradient streams

    Science.gov (United States)

    Gleeson, Tom; Manning, Andrew H.; Popp, Andrea; Zane, Mathew; Clark, Jordan F.

    2018-01-01

    Determining groundwater discharge to streams using dissolved gases is known to be useful over a wide range of streamflow rates but the suitability of dissolved gas methods to determine discharge rates in high gradient mountain streams has not been sufficiently tested, even though headwater streams are critical as ecological habitats and water resources. The aim of this study is to test the suitability of using dissolved gases to determine groundwater discharge rates to high gradient streams by field experiments in a well-characterized, high gradient mountain stream and a literature review. At a reach scale (550 m) we combined stream and groundwater radon activity measurements with an in-stream SF6 tracer test. By means of numerical modeling we determined gas exchange velocities and derived very low groundwater discharge rates (∼15% of streamflow). These groundwater discharge rates are below the uncertainty range of physical streamflow measurements and consistent with temperature, specific conductance and streamflow measured at multiple locations along the reach. At a watershed-scale (4 km), we measured CFC-12 and δ18O concentrations and determined gas exchange velocities and groundwater discharge rates with the same numerical model. The groundwater discharge rates along the 4 km stream reach were highly variable, but were consistent with the values derived in the detailed study reach. Additionally, we synthesized literature values of gas exchange velocities for different stream gradients which show an empirical relationship that will be valuable in planning future dissolved gas studies on streams with various gradients. In sum, we show that multiple dissolved gas tracers can be used to determine groundwater discharge to high gradient mountain streams from reach to watershed scales.

  2. The suitability of using dissolved gases to determine groundwater discharge to high gradient streams

    Science.gov (United States)

    Gleeson, Tom; Manning, Andrew H.; Popp, Andrea; Zane, Matthew; Clark, Jordan F.

    2018-02-01

    Determining groundwater discharge to streams using dissolved gases is known to be useful over a wide range of streamflow rates but the suitability of dissolved gas methods to determine discharge rates in high gradient mountain streams has not been sufficiently tested, even though headwater streams are critical as ecological habitats and water resources. The aim of this study is to test the suitability of using dissolved gases to determine groundwater discharge rates to high gradient streams by field experiments in a well-characterized, high gradient mountain stream and a literature review. At a reach scale (550 m) we combined stream and groundwater radon activity measurements with an in-stream SF6 tracer test. By means of numerical modeling we determined gas exchange velocities and derived very low groundwater discharge rates (∼15% of streamflow). These groundwater discharge rates are below the uncertainty range of physical streamflow measurements and consistent with temperature, specific conductance and streamflow measured at multiple locations along the reach. At a watershed-scale (4 km), we measured CFC-12 and δ18O concentrations and determined gas exchange velocities and groundwater discharge rates with the same numerical model. The groundwater discharge rates along the 4 km stream reach were highly variable, but were consistent with the values derived in the detailed study reach. Additionally, we synthesized literature values of gas exchange velocities for different stream gradients which show an empirical relationship that will be valuable in planning future dissolved gas studies on streams with various gradients. In sum, we show that multiple dissolved gas tracers can be used to determine groundwater discharge to high gradient mountain streams from reach to watershed scales.

  3. Intermittency in the particle production and in the nuclear multifragmentation

    International Nuclear Information System (INIS)

    Bozek, P.; Ploszajczak, M.

    1991-01-01

    Intermittency is a manifestation of scale invariance and randomness in physical systems. Intermittency in relativistic heavy-ion collisions and, in particular, the projectile dependence, multiplicity dependence and source-size dependence are discussed in the frame of the model of spatio-temporal intermittency. Moreover, recent theoretical results in intermittency studies of the nuclear multifragmentation are presented. (author) 35 refs., 4 figs., 1 tab

  4. Temporal change of SF6 age in spring during rainstorms in a forested headwater catchment, Fukushima, Japan

    Science.gov (United States)

    Sakakibara, Koichi; Tsujimura, Maki; Onda, Yuichi; Iwagami, Sho; Sato, Yutaro; Nagano, Kosuke

    2017-04-01

    Time variant water age in catchments can fundamentally describe catchment function, controlling rainfall-runoff generation, groundwater flow pathway, and water storage. We observed sulfur hexafluoride concentration in the stream and groundwater with 1 - 2 hours interval during rainstorm events in order to reveal temporal variations of rainfall-runoff water age. Target's spring is perennial in a forested headwater catchment with an area of 0.045 square km, Fukushima, Japan. The observed hydrological data and tracer data of water in the catchment (stable isotopic compositions, inorganic solute concentrations) were used for clarifying rainfall-runoff processes related to water age variances. The storm hydrograph and groundwater table clearly responded to rainfall especially with more than 30 mm per day throughout the monitoring period (May 2015 - October 2016). Large variations of SF6 age in spring ranging from zero to 14 years were found in the short period during rainstorms. In particular, the SF6 age in spring was evidently old when the runoff was over 2 mm per day. At the high runoff condition, the SF6 age in spring positively correlated with discharge rate: the spring age became older as the discharge rate increased. With regard to spatial distributions of SF6 age in groundwater, the old groundwater age (9 - 13 years) in the shallow subsurface area along the valley was confirmed after heavy rainfall. This groundwater age was similar age to the deep groundwater at no-rainfall conditions. In addition, inorganic solute concentrations such as chloride ion, sodium ion, and silica in spring water showed dominant levels in the deep and ridge groundwater. All facts suggest that the old groundwater, stored in the ridge or deeper subsurface area, replaced the shallow groundwater in the vicinity of the spring due to heavy rainfall, then it contributed to the spring discharge. Therefore, rainstorm events play important roles as triggers for discharging older water stored in

  5. Benthic invertebrate fauna, small streams

    Science.gov (United States)

    J. Bruce Wallace; S.L. Eggert

    2009-01-01

    Small streams (first- through third-order streams) make up >98% of the total number of stream segments and >86% of stream length in many drainage networks. Small streams occur over a wide array of climates, geology, and biomes, which influence temperature, hydrologic regimes, water chemistry, light, substrate, stream permanence, a basin's terrestrial plant...

  6. Intermittent Rivers and Biodiversity. Large scale analyses between hydrology and ecology in intermittent rivers

    OpenAIRE

    Blanchard, Q.

    2014-01-01

    Intermittent rivers are characterized by a temporary interruption of their flow which can manifest in a variety of ways, as much on a spatial scale as on a temporal one. This particular aspect of intermittent river hydrology gives rise to unique ecosystems, combining both aquatic and terrestrial habitats. Neglected for a long time by scientists and once considered biologically depauperate and ecologically unimportant, these fragile habitats are nowadays acknowledged for their rendered service...

  7. Effects of seasonality and resource limitation on organic matter turnover by Chironomidae (Diptera) in southern Appalachian headwater streams

    Science.gov (United States)

    Angela Romito; Susan Eggert; Jeffrey Diez; J. Wallace

    2010-01-01

    Despite their high abundance, secondary production, and known reliance on detrital material, the role of chironomids (Diptera) in fine particulate organic matter (FPOM) dynamics has not been well quantified. We conducted field trials using fluorescent pigment markers to estimate seasonal rates of consumption, annual secondary production, assimilation efficiency (AE),...

  8. Spatially distributed characterization of hyporheic solute transport during baseflow recession in a headwater mountain stream using electrical geophysical imaging

    Science.gov (United States)

    Adam S. Ward; Michael N. Gooseff; Michael Fitzgerald; Thomas J. Voltz; Kamini Singha

    2014-01-01

    The transport of solutes along hyporheic flowpaths is recognized as central to numerous biogeochemical cycles, yet our understanding of how this transport changes with baseflow recession, particularly in a spatially distributed manner, is limited. We conducted four steady-state solute tracer injections and collected electrical resistivity data to characterize hyporheic...

  9. Classification of the alterations of beaver dams to headwater streams in northeastern Connecticut, U.S.A.

    Science.gov (United States)

    Burchsted, Denise; Daniels, Melinda D.

    2014-01-01

    Of the many types of barriers to water flow, beaver dams are among the smallest, typically lasting less than a decade and rarely exceeding 1.5 m in height. They are also among the most frequent and common obstructions in rivers, with a density often exceeding ten dams per km, a frequency of construction within a given network on a time scale of years, and a historic extent covering most of North America. Past quantification of the geomorphologic impact of beaver dams has primarily been limited to local impacts within individual impoundments and is of limited geographic scope. To assess the impact of beaver dams at larger scales, this study examines channel shape and sediment distribution in thirty river reaches in northeastern Connecticut, U.S.A. The study reaches fall within the broader categories of impounded and free-flowing segments, leaving a third segment class of beaver meadows requiring additional study. Each of the study reaches were classified at the reach scale as free-flowing, valley-wide beaver pond, in-channel beaver pond, and downstream of beaver dam. The bankfull channel width to depth ratios and channel widths normalized by watershed area vary significantly across the study reach classes. Additionally, reaches modified by beaver dams have finer sediment distributions. This paper provides the first quantitative geomorphic descriptions of the in-channel beaver pond and reaches downstream of beaver dams. Given the different channel shapes and sediment distributions, we infer that geomorphic processes are longitudinally decoupled by these frequent barriers that control local base level. These barriers generate heterogeneity within a river network by greatly increasing the range of channel morphology and by generating patches controlled by different processes. Therefore, in spite of the small size of individual beaver dams, the cumulative effect of multiple dams has the potential to modify processes at larger spatial scales. To improve assessment of the larger-scale impacts, we propose a hierarchical classification scheme based on discontinuities, place the reach classes of this study within that scheme, and suggest that further research should continue investigation of discontinuity at the network scale and quantification of the cumulative impacts.

  10. Conservation value of post-mining headwaters: drainage channels at a lignite spoil heap harbour threatened stream fragonflies

    Czech Academy of Sciences Publication Activity Database

    Tichánek, Filip; Tropek, Robert

    2015-01-01

    Roč. 19, č. 5 (2015), s. 975-985 ISSN 1366-638X R&D Projects: GA ČR GAP504/12/2525 Grant - others:GA JU(CZ) 168/2013/P Institutional support: RVO:60077344 Keywords : biodiversity conservation * drainage ditches * freshwater habitats Subject RIV: EH - Ecology, Behaviour Impact factor: 1.431, year: 2015 http://link.springer.com/article/10.1007%2Fs10841-015-9814-1

  11. Effects of insect and decapod exclusion and leaf litter species identity on breakdown rates in a tropical headwater stream

    Directory of Open Access Journals (Sweden)

    José Rincón

    2014-04-01

    Full Text Available La gran variedad de especies vegetales junto a los ríos tropicales afecta la diversidad de detritos orgánicos que llegan a los arroyos, creando variaciones temporales en cantidad y calidad de hojarasca. Examinamos la influencia de las especies vegetales y de la exclusión de macroinvertebrados sobre la descomposición de hojarasca en la parte alta de un arroyo en las montañas Luquillo de Puerto Rico. Incubamos hojarasca de Dacryodes excelsa (Burseraceae, Guarea guidonia (Meliaceae, Cecropia scheberiana (Moraceae, Manilkara bidentata (Sapotaceae y Prestoea acuminata (Palmae en bolsas descomposición que colocamos en una poza de Quebrada Prieta. Usamos bolsas de malla fina para excluir los macroinvertebrados y de malla gruesa para permitir la entrada a crustáceos decápodos (camarones y cangrejos jóvenes e insectos acuáticos (principalmente efemerópteros, quironómidos y tricópteros. D. excelsa y G. guidonia (en ambos tipos de malla tuvieron tasas de descomposición más altas que C. scheberiana, M. bidentata y P. acuminata. La descomposición fue más rápida para todas las especies de hoja con la malla gruesa, resaltando el papel de los descomponedores en este hábitat. Tras 42 días de esta incubación, las densidades totales de invertebrados, efemerópteros y tricópteros fueron mayores en las bolsas con hojas de D. excelsa y G. guidonia, e inferiores en P. acuminata, C. scheberiana y M. bidentata. A mayor densidad de insectos hubo mayor tasa de descomposición. Nuestros resultados indican la importancia de la especie de las hojas y de la presencia de macroinvertebrados en el proceso de descomposición de hojarasca en partes altas de arroyos tropicales.

  12. Combined effects of hydrologic alteration and cyprinid fish in mediating biogeochemical processes in a Mediterranean stream.

    Science.gov (United States)

    Rubio-Gracia, Francesc; Almeida, David; Bonet, Berta; Casals, Frederic; Espinosa, Carmen; Flecker, Alexander S; García-Berthou, Emili; Martí, Eugènia; Tuulaikhuu, Baigal-Amar; Vila-Gispert, Anna; Zamora, Lluis; Guasch, Helena

    2017-12-01

    Flow regimes are important drivers of both stream community and biogeochemical processes. However, the interplay between community and biogeochemical responses under different flow regimes in streams is less understood. In this study, we investigated the structural and functional responses of periphyton and macroinvertebrates to different densities of the Mediterranean barbel (Barbus meridionalis, Cyprinidae) in two stream reaches differing in flow regime. The study was conducted in Llémena Stream, a small calcareous Mediterranean stream with high nutrient levels. We selected a reach with permanent flow (permanent reach) and another subjected to flow regulation (regulated reach) with periods of flow intermittency. At each reach, we used in situ cages to generate 3 levels of fish density. Cages with 10 barbels were used to simulate high fish density (>7indm -2 ); cages with open sides were used as controls (i.e. exposed to actual fish densities of each stream reach) thus having low fish density; and those with no fish were used to simulate the disappearance of fish that occurs with stream drying. Differences in fish density did not cause significant changes in periphyton biomass and macroinvertebrate density. However, phosphate uptake by periphyton was enhanced in treatments lacking fish in the regulated reach with intermittent flow but not in the permanent reach, suggesting that hydrologic alteration hampers the ability of biotic communities to compensate for the absence of fish. This study indicates that fish density can mediate the effects of anthropogenic alterations such as flow intermittence derived from hydrologic regulation on stream benthic communities and associated biogeochemical processes, at least in eutrophic streams. Copyright © 2017. Published by Elsevier B.V.

  13. Drivers of nitrogen transfer in stream food webs across continents.

    Science.gov (United States)

    Norman, Beth C; Whiles, Matt R; Collins, Sarah M; Flecker, Alexander S; Hamilton, Steve K; Johnson, Sherri L; Rosi, Emma J; Ashkenas, Linda R; Bowden, William B; Crenshaw, Chelsea L; Crowl, Todd; Dodds, Walter K; Hall, Robert O; El-Sabaawi, Rana; Griffiths, Natalie A; Marti, Eugènia; McDowell, William H; Peterson, Scot D; Rantala, Heidi M; Riis, Tenna; Simon, Kevin S; Tank, Jennifer L; Thomas, Steven A; von Schiller, Daniel; Webster, Jackson R

    2017-12-01

    Studies of trophic-level material and energy transfers are central to ecology. The use of isotopic tracers has now made it possible to measure trophic transfer efficiencies of important nutrients and to better understand how these materials move through food webs. We analyzed data from thirteen 15 N-ammonium tracer addition experiments to quantify N transfer from basal resources to animals in headwater streams with varying physical, chemical, and biological features. N transfer efficiencies from primary uptake compartments (PUCs; heterotrophic microorganisms and primary producers) to primary consumers was lower (mean 11.5%, range 100%). Total N transferred (as a rate) was greater in streams with open compared to closed canopies and overall N transfer efficiency generally followed a similar pattern, although was not statistically significant. We used principal component analysis to condense a suite of site characteristics into two environmental components. Total N uptake rates among trophic levels were best predicted by the component that was correlated with latitude, DIN:SRP, GPP:ER, and percent canopy cover. N transfer efficiency did not respond consistently to environmental variables. Our results suggest that canopy cover influences N movement through stream food webs because light availability and primary production facilitate N transfer to higher trophic levels. © 2017 by the Ecological Society of America.

  14. Solar wind stream interfaces

    International Nuclear Information System (INIS)

    Gosling, J.T.; Asbridge, J.R.; Bame, S.J.; Feldman, W.C.

    1978-01-01

    Measurements aboard Imp 6, 7, and 8 reveal that approximately one third of all high-speed solar wind streams observed at 1 AU contain a sharp boundary (of thickness less than approx.4 x 10 4 km) near their leading edge, called a stream interface, which separates plasma of distinctly different properties and origins. Identified as discontinuities across which the density drops abruptly, the proton temperature increases abruptly, and the speed rises, stream interfaces are remarkably similar in character from one stream to the next. A superposed epoch analysis of plasma data has been performed for 23 discontinuous stream interfaces observed during the interval March 1971 through August 1974. Among the results of this analysis are the following: (1) a stream interface separates what was originally thick (i.e., dense) slow gas from what was originally thin (i.e., rare) fast gas; (2) the interface is the site of a discontinuous shear in the solar wind flow in a frame of reference corotating with the sun; (3) stream interfaces occur at speeds less than 450 km s - 1 and close to or at the maximum of the pressure ridge at the leading edges of high-speed streams; (4) a discontinuous rise by approx.40% in electron temperature occurs at the interface; and (5) discontinuous changes (usually rises) in alpha particle abundance and flow speed relative to the protons occur at the interface. Stream interfaces do not generally recur on successive solar rotations, even though the streams in which they are embedded often do. At distances beyond several astronomical units, stream interfaces should be bounded by forward-reverse shock pairs; three of four reverse shocks observed at 1 AU during 1971--1974 were preceded within approx.1 day by stream interfaces. Our observations suggest that many streams close to the sun are bounded on all sides by large radial velocity shears separating rapidly expanding plasma from more slowly expanding plasma

  15. Hydrologic cycle and dynamics of aquatic macrophytes in two intermittent rivers of the semi-arid region of Brazil

    Directory of Open Access Journals (Sweden)

    F. Pedro

    Full Text Available The dynamics of aquatic macrophytes in intermittent rivers is generally related to the characteristics of the resistance and resilience of plants to hydrologic disturbances of flood and drought. In the semi-arid region of Brazil, intermittent rivers and streams are affected by disturbances with variable intensity, frequency, and duration throughout their hydrologic cycles. The aim of the present study is to determine the occurrence and variation of biomass of aquatic macrophyte species in two intermittent rivers of distinct hydrologic regimes. Their dynamics were determined with respect to resistance and resilience responses of macrophytes to flood and drought events by estimating the variation of biomass and productivity throughout two hydrologic cycles. Twenty-one visits were undertaken in the rewetting, drying, and drought phases in a permanent puddle in the Avelós stream and two temporary puddles in the Taperoá river, state of Paraíba, Northeast Brazil. The sampling was carried out by using the square method. Floods of different magnitudes occurred during the present study in the river and in the stream. The results showed that floods and droughts are determining factors in the occurrence of macrophytes and in the structure of their aquatic communities. The species richness of the aquatic macrophyte communities was lower in the puddles of the river and stream subject to flood events, when compared to areas where the run-off water is retained. At the beginning of the recolonization process, the intensity of the floods was decisive in the productivity and biomass of the aquatic macrophytes in the Taperoá river and the Avelós stream. In intermediate levels of disturbance, the largest values of productivity and biomass and the shortest time for starting the recolonization process occurred.

  16. Evaluation of catch-and-release regulations on Brook Trout in Pennsylvania streams

    Science.gov (United States)

    Jason Detar,; Kristine, David; Wagner, Tyler; Greene, Tom

    2014-01-01

    In 2004, the Pennsylvania Fish and Boat Commission implemented catch-and-release (CR) regulations on headwater stream systems to determine if eliminating angler harvest would result in an increase in the number of adult (≥100 mm) or large (≥175 mm) Brook Trout Salvelinus fontinalis. Under the CR regulations, angling was permitted on a year-round basis, no Brook Trout could be harvested at any time, and there were no tackle restrictions. A before-after–control-impact design was used to evaluate the experimental regulations. Brook Trout populations were monitored in 16 treatment (CR regulations) and 7 control streams (statewide regulations) using backpack electrofishing gear periodically for up to 15 years (from 1990 to 2003 or 2004) before the implementation of the CR regulations and over a 7–8-year period (from 2004 or 2005 to 2011) after implementation. We used Poisson mixed models to evaluate whether electrofishing catch per effort (CPE; catch/100 m2) of adult (≥100 mm) or large (≥175 mm) Brook Trout increased in treatment streams as a result of implementing CR regulations. Brook Trout CPE varied among sites and among years, and there was no significant effect (increase or decrease) of CR regulations on the CPE of adult or large Brook Trout. Results of our evaluation suggest that CR regulations were not effective at improving the CPE of adult or large Brook Trout in Pennsylvania streams. Low angler use, high voluntary catch and release, and slow growth rates in infertile headwater streams are likely the primary reasons for the lack of response.

  17. Simulation of dynamic expansion, contraction, and connectivity in a mountain stream network

    Science.gov (United States)

    Ward, Adam S.; Schmadel, Noah M.; Wondzell, Steven M.

    2018-04-01

    Headwater stream networks expand and contract in response to changes in stream discharge. The changes in the extent of the stream network are also controlled by geologic or geomorphic setting - some reaches go dry even under relatively wet conditions, other reaches remain flowing under relatively dry conditions. While such patterns are well recognized, we currently lack tools to predict the extent of the stream network and the times and locations where the network is dry within large river networks. Here, we develop a perceptual model of the river corridor in a headwater mountainous catchment, translate this into a reduced-complexity mechanistic model, and implement the model to examine connectivity and network extent over an entire water year. Our model agreed reasonably well with our observations, showing that the extent and connectivity of the river network was most sensitive to hydrologic forcing under the lowest discharges (Qgauge 10 L s-1) the extent of the network was relatively insensitive to hydrologic forcing and was instead determined by the network topology. We do not expect that the specific thresholds observed in this study would be transferable to other catchments with different geology, topology, or hydrologic forcing. However, we expect that the general pattern should be robust: the dominant controls will shift from hydrologic forcing to geologic setting as discharge increases. Furthermore, our method is readily transferable as the model can be applied with minimal data requirements (a single stream gauge, a digital terrain model, and estimates of hydrogeologic properties) to estimate flow duration or connectivity along the river corridor in unstudied catchments. As the available information increases, the model could be better calibrated to match site-specific observations of network extent, locations of dry reaches, or solute break through curves as demonstrated in this study. Based on the low initial data requirements and ability to later tune

  18. Future climate and changes in flow patterns in Czech headwater catchments

    Czech Academy of Sciences Publication Activity Database

    Benčoková, A.; Krám, P.; Hruška, Jakub

    2011-01-01

    Roč. 49, č. 1 (2011), s. 1-15 ISSN 0936-577X R&D Projects: GA MŠk(CZ) ED1.1.00/02.0073 Institutional research plan: CEZ:AV0Z60870520 Keywords : climate change impact * flow pattern * regional climate scenarios * Headwater catchments * hydrological modelling * Broo90 Subject RIV: DA - Hydrology ; Limnology Impact factor: 1.994, year: 2011

  19. Estimating shallow groundwater recharge in the headwaters of the Liverpool Plains using SWAT

    OpenAIRE

    Sun, H.; Cornish, P.S.

    2005-01-01

    Metadata only record A physically based catchment model (SWAT) was used for recharge estimation in the headwaters of the Liverpool Plains in NSW, Australia. The study used water balance modelling at the catchment scale to derive parameters for long-term recharge estimation. The derived parameters were further assessed at a subcatchment scale. Modelling results suggest that recharge occurs only in wet years, and is dominated by a few significant years or periods. The results were matched by...

  20. The use of coupled atmospheric and hydrological models for water-resources management in headwater basins

    Science.gov (United States)

    Leavesley, G.; Hay, L.

    1998-01-01

    Coupled atmospheric and hydrological models provide an opportunity for the improved management of water resources in headwater basins. Issues currently limiting full implementation of coupled-model methodologies include (a) the degree of uncertainty in the accuracy of precipitation and other meteorological variables simulated by atmospheric models, and (b) the problem of discordant scales between atmospheric and bydrological models. Alternative methodologies being developed to address these issues are reviewed.

  1. Episodic runoff generation at Central European headwater catchments studied using water isotope concentration signals

    Czech Academy of Sciences Publication Activity Database

    Votrubová, J.; Dohnal, M.; Vogel, T.; Šanda, M.; Tesař, Miroslav

    2017-01-01

    Roč. 65, č. 2 (2017), s. 114-122 ISSN 0042-790X Grant - others:Grantová agentura České republiky (GA ČR)(CZ) GC14-15201J Institutional support: RVO:67985874 Keywords : O isotope * headwater catchment runoff * subsurface runoff * tracer * rainfall-runoff episodes Subject RIV: DA - Hydrology ; Limnology OBOR OECD: Hydrology Impact factor: 1.654, year: 2016

  2. Storm runoff in the foothill headwater area Senotín

    Czech Academy of Sciences Publication Activity Database

    Tesař, Miroslav; Syrovátka, O.; Šír, Miloslav; Lichner, Ľ.; Váchal, J.; Krejča, M.

    2008-01-01

    Roč. 3, č. 3 (2008), s. 168-174 ISSN 1801-5395 R&D Projects: GA ČR GA526/98/0805; GA AV ČR IAA3060701 Institutional research plan: CEZ:AV0Z20600510 Keywords : headwater area * storm runoff * water retention * runoff retardation Subject RIV: DA - Hydrology ; Limnology http://journals.uzpi.cz:8050/uniqueFiles/02525.pdf

  3. Spatial patterns of stream temperatures and electric conductivity in a mesoscale catchment

    Science.gov (United States)

    Lieder, Ernestine; Weiler, Markus; Blume, Theresa

    2017-04-01

    Stream temperature and electric conductivity (EC) are both relatively easily measured and can provide valuable information on runoff generation processes and catchment storage.This study investigates the spatial variability of stream temperature and EC in a mesoscale basin. We focus on the mesoscale (sub-catchments and reach scale), and long term (seasonal / annual) stream temperature and EC patterns. Our study basin is the Attert catchment in Luxembourg (288km2), which contains multiple sub-catchments of different geology, topography and land use patterns. We installed 90 stream temperature and EC sensors at sites across the basin in summer 2015. The collected data is complemented by land use and discharge data and an extensive climate data set. Thermal sensitivity was calculated as the slope of daily air temperature-water-temperature regression line and describes the sensitivity of stream temperature to long term environmental change. Amplitude sensitivity was calculated as slope of the daily air and water temperature amplitude regression and describes the short term warming capacity of the stream. We found that groups with similar long term thermal and EC patterns are strongly related to different geological units. The sandstone reaches show the coldest temperatures and lowest annual thermal sensitivity to air temperature. The slate reaches are characterized by comparably low EC and high daily temperature amplitudes and amplitude sensitivity. Furthermore, mean annual temperatures and thermal sensitivities increase exponentially with drainage area, which can be attributed to the accumulation of heat throughout the system. On the reach scale, daily stream temperature fluctuations or sensitivities were strongly influenced by land cover distribution, stream shading and runoff volume. Daily thermal sensitivities were low for headwater streams; peaked for intermediate reaches in the middle of the catchment and then decreased again further downstream with increasing

  4. Intermittent control: a computational theory of human control.

    Science.gov (United States)

    Gawthrop, Peter; Loram, Ian; Lakie, Martin; Gollee, Henrik

    2011-02-01

    The paradigm of continuous control using internal models has advanced understanding of human motor control. However, this paradigm ignores some aspects of human control, including intermittent feedback, serial ballistic control, triggered responses and refractory periods. It is shown that event-driven intermittent control provides a framework to explain the behaviour of the human operator under a wider range of conditions than continuous control. Continuous control is included as a special case, but sampling, system matched hold, an intermittent predictor and an event trigger allow serial open-loop trajectories using intermittent feedback. The implementation here may be described as "continuous observation, intermittent action". Beyond explaining unimodal regulation distributions in common with continuous control, these features naturally explain refractoriness and bimodal stabilisation distributions observed in double stimulus tracking experiments and quiet standing, respectively. Moreover, given that human control systems contain significant time delays, a biological-cybernetic rationale favours intermittent over continuous control: intermittent predictive control is computationally less demanding than continuous predictive control. A standard continuous-time predictive control model of the human operator is used as the underlying design method for an event-driven intermittent controller. It is shown that when event thresholds are small and sampling is regular, the intermittent controller can masquerade as the underlying continuous-time controller and thus, under these conditions, the continuous-time and intermittent controller cannot be distinguished. This explains why the intermittent control hypothesis is consistent with the continuous control hypothesis for certain experimental conditions.

  5. Inventory of miscellaneous streams

    International Nuclear Information System (INIS)

    Lueck, K.J.

    1995-09-01

    On December 23, 1991, the US Department of Energy, Richland Operations Office (RL) and the Washington State Department of Ecology (Ecology) agreed to adhere to the provisions of the Department of Ecology Consent Order. The Consent Order lists the regulatory milestones for liquid effluent streams at the Hanford Site to comply with the permitting requirements of Washington Administrative Code. The RL provided the US Congress a Plan and Schedule to discontinue disposal of contaminated liquid effluent into the soil column on the Hanford Site. The plan and schedule document contained a strategy for the implementation of alternative treatment and disposal systems. This strategy included prioritizing the streams into two phases. The Phase 1 streams were considered to be higher priority than the Phase 2 streams. The actions recommended for the Phase 1 and 2 streams in the two reports were incorporated in the Hanford Federal Facility Agreement and Consent Order. Miscellaneous Streams are those liquid effluents streams identified within the Consent Order that are discharged to the ground but are not categorized as Phase 1 or Phase 2 Streams. This document consists of an inventory of the liquid effluent streams being discharged into the Hanford soil column

  6. Hydrography - Streams and Shorelines

    Data.gov (United States)

    California Natural Resource Agency — The hydrography layer consists of flowing waters (rivers and streams), standing waters (lakes and ponds), and wetlands -- both natural and manmade. Two separate...

  7. CONDITIONED ANALYSIS OF HIGH-LATITUDE SOLAR WIND INTERMITTENCY

    International Nuclear Information System (INIS)

    D'Amicis, R.; Consolini, G.; Bavassano, B.; Bruno, R.

    2012-01-01

    The solar wind is a turbulent medium displaying intermittency. Its intermittent features have been widely documented and studied, showing how the intermittent character is different in fast and slow wind. In this paper, a statistical conditioned analysis of the solar wind intermittency for a period of high-latitude fast solar wind is presented. In particular, the intermittent features are investigated as a function of the Alfvénic degree of fluctuations at a given scale. The results show that the main contribution to solar wind intermittency is due to non-Alfvénic structures, while Alfvénic increments are found to be characterized by a smaller level of intermittency than the previous ones. Furthermore, the lifetime statistics of Alfvénic periods are discussed in terms of a multiscale texture of randomly oriented flux tubes.

  8. Climate Change Impacts on Sediment Yield in Headwaters of a High-latitude Region in China

    Science.gov (United States)

    Zhou, Y.; Xu, Y. J.; Wang, J., , Dr; Weihua, X.; Huang, Y.

    2017-12-01

    Climate change is expected to have strongest effects in higher latitude regions. Despite intensive research on possible hydrological responses to global warming in these regions, our knowledge of climate change on surface erosion and sediment yield in high-latitude headwaters is limited. In this study, we used the Soil and Water Assessment Tool (SWAT) to predict future runoff and sediment yield from the headwaters of a high-latitude river basin in China's far northeast. The SWAT model was first calibrated with historical discharge records and the model parameterization achieved satisfactory validation. The calibrated model was then applied to two greenhouse gas concentration trajectories, RCP4.5 and RCP8.5, for the period from 2020 to 2050 to estimate future runoff. Sediment yields for this period were predicted using a discharge-sediment load rating curve developed from field measurements in the past nine years. Our preliminary results show an increasing trend of sediment yield under both climate change scenarios, and that the increase is more pronounced in the summer and autumn months. Changes in precipitation and temperature seem to exert variable impacts on runoff and sediment yield at interannual and seasonal scales in these headwaters. These findings imply that the current river basin management in the region needs to be reviewed and improved in order to be effective under a changing climate.

  9. Assessment of groundwater–surface water interaction using long-term hydrochemical data and isotope hydrology: Headwaters of the Condamine River, Southeast Queensland, Australia

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, Jorge L., E-mail: jlmarti@ig.com.br [Queensland University of Technology, Brisbane (Australia); Raiber, Matthias [CSIRO Land and Water Flagship, Brisbane (Australia); Cox, Malcolm E. [Queensland University of Technology, Brisbane (Australia)

    2015-12-01

    A spatial analysis of hydrochemical data of groundwater and surface water was undertaken to identify groundwater-surface water connectivity in the headwaters of the Condamine River catchment, Southeast Queensland, Australia. An assessment of long-term hydrochemical and water level data supplemented by stable- and radioisotope measurements following a prolonged dry period dominated by baseflow, helped in determining patterns of interaction in different tributaries of the upper Condamine catchment. A conceptual hydrological model representing the major hydrochemical processes and their implications for stream-aquifer connectivity was developed and tested using multiple lines of evidence. The results of a multivariate statistical analysis highlight that there are two main regions with distinct hydrochemical facies (salinity, alkalinity, and predominant ions) in surface water. Geomorphology, geology, anthropogenic and climate influence were identified as the most relevant controlling factors of the spatial variability in water quality. Stable isotope data confirmed a clear evaporation trend in almost all surface water samples during baseflow conditions. Two water types can be identified and separated by the degree of evaporation and the proximity of one group to the local meteoric water line. The results confirm the discharge of groundwater from aquifers recharged by rainfall and located upstream of the surface water sampling sites. Overall, {sup 222}Rn data show a trend of increased activity in surface water towards the upstream portions of these tributaries, validating the use of this tracer to estimate groundwater input to the local creeks. The proportion of groundwater contribution to stream flow calculated by {sup 222}Rn and chloride mass balance is in agreement, and ranges between 20–70% in tributaries in the northern areas, and between 8–50% in the upper reaches of the main river channel. This study shows the efficacy of an integrated approach combining long

  10. Assessment of groundwater–surface water interaction using long-term hydrochemical data and isotope hydrology: Headwaters of the Condamine River, Southeast Queensland, Australia

    International Nuclear Information System (INIS)

    Martinez, Jorge L.; Raiber, Matthias; Cox, Malcolm E.

    2015-01-01

    A spatial analysis of hydrochemical data of groundwater and surface water was undertaken to identify groundwater-surface water connectivity in the headwaters of the Condamine River catchment, Southeast Queensland, Australia. An assessment of long-term hydrochemical and water level data supplemented by stable- and radioisotope measurements following a prolonged dry period dominated by baseflow, helped in determining patterns of interaction in different tributaries of the upper Condamine catchment. A conceptual hydrological model representing the major hydrochemical processes and their implications for stream-aquifer connectivity was developed and tested using multiple lines of evidence. The results of a multivariate statistical analysis highlight that there are two main regions with distinct hydrochemical facies (salinity, alkalinity, and predominant ions) in surface water. Geomorphology, geology, anthropogenic and climate influence were identified as the most relevant controlling factors of the spatial variability in water quality. Stable isotope data confirmed a clear evaporation trend in almost all surface water samples during baseflow conditions. Two water types can be identified and separated by the degree of evaporation and the proximity of one group to the local meteoric water line. The results confirm the discharge of groundwater from aquifers recharged by rainfall and located upstream of the surface water sampling sites. Overall, 222 Rn data show a trend of increased activity in surface water towards the upstream portions of these tributaries, validating the use of this tracer to estimate groundwater input to the local creeks. The proportion of groundwater contribution to stream flow calculated by 222 Rn and chloride mass balance is in agreement, and ranges between 20–70% in tributaries in the northern areas, and between 8–50% in the upper reaches of the main river channel. This study shows the efficacy of an integrated approach combining long

  11. Intermittent character of interplanetary magnetic field fluctuations

    International Nuclear Information System (INIS)

    Bruno, Roberto; Carbone, Vincenzo; Chapman, Sandra; Hnat, Bogdan; Noullez, Alain; Sorriso-Valvo, Luca

    2007-01-01

    Interplanetary magnetic field magnitude fluctuations are notoriously more intermittent than velocity fluctuations in both fast and slow wind. This behavior has been interpreted in terms of the anomalous scaling observed in passive scalars in fully developed hydrodynamic turbulence. In this paper, the strong intermittent nature of the interplanetary magnetic field is briefly discussed comparing results performed during different phases of the solar cycle. The scaling properties of the interplanetary magnetic field magnitude show solar cycle variation that can be distinguished in the scaling exponents revealed by structure functions. The scaling exponents observed around the solar maximum coincide, within the errors, to those measured for passive scalars in hydrodynamic turbulence. However, it is also found that the values are not universal in the sense that the solar cycle variation may be reflected in dependence on the structure of the velocity field

  12. Intermittency exponent of the turbulent energy cascade

    International Nuclear Information System (INIS)

    Cleve, J.; Greiner, M.; Pearson, B.R.; Sreenivasan, K.R.

    2006-12-01

    We consider the turbulent energy dissipation from one-dimensional records in experiments using air and gaseous helium at cryogenic temperatures, and obtain the intermittency exponent via the two-point correlation function of the energy dissipation. The air data are obtained in a number of flows in a wind tunnel and the atmospheric boundary layer at a height of about 35 m above the ground. The helium data correspond to the centerline of a jet exhausting into a container. The air data on the intermittency exponent are consistent with each other and with a trend that increases with the Taylor microscale Reynolds number, R λ , of up to about 1000 and saturates thereafter. On the other hand, the helium data cluster around a constant value at nearly all R λ , this being about half of the asymptotic value for the air data. Some possible explanation is offered for this anomaly. (author)

  13. Effects of intermittent hypoxia on running economy.

    Science.gov (United States)

    Burtscher, M; Gatterer, H; Faulhaber, M; Gerstgrasser, W; Schenk, K

    2010-09-01

    We investigated the effects of two 5-wk periods of intermittent hypoxia on running economy (RE). 11 male and female middle-distance runners were randomly assigned to the intermittent hypoxia group (IHG) or to the control group (CG). All athletes trained for a 13-wk period starting at pre-season until the competition season. The IHG spent additionally 2 h at rest on 3 days/wk for the first and the last 5 weeks in normobaric hypoxia (15-11% FiO2). RE, haematological parameters and body composition were determined at low altitude (600 m) at baseline, after the 5 (th), the 8 (th) and the 13 (th) week of training. RE, determined by the relative oxygen consumption during submaximal running, (-2.3+/-1.2 vs. -0.3+/-0.7 ml/min/kg, Ptraining phase. Georg Thieme Verlag KG Stuttgart . New York.

  14. Optimal intermittent search strategies: smelling the prey

    International Nuclear Information System (INIS)

    Revelli, J A; Wio, H S; Rojo, F; Budde, C E

    2010-01-01

    We study the kinetics of the search of a single fixed target by a searcher/walker that performs an intermittent random walk, characterized by different states of motion. In addition, we assume that the walker has the ability to detect the scent left by the prey/target in its surroundings. Our results, in agreement with intuition, indicate that the prey's survival probability could be strongly reduced (increased) if the predator is attracted (or repelled) by the trace left by the prey. We have also found that, for a positive trace (the predator is guided towards the prey), increasing the inhomogeneity's size reduces the prey's survival probability, while the optimal value of α (the parameter that regulates intermittency) ceases to exist. The agreement between theory and numerical simulations is excellent.

  15. Optimal intermittent search strategies: smelling the prey

    Energy Technology Data Exchange (ETDEWEB)

    Revelli, J A; Wio, H S [Instituto de Fisica de Cantabria, Universidad de Cantabria and CSIC, E-39005 Santander (Spain); Rojo, F; Budde, C E [Fa.M.A.F., Universidad Nacional de Cordoba, Ciudad Universitaria, X5000HUA Cordoba (Argentina)

    2010-05-14

    We study the kinetics of the search of a single fixed target by a searcher/walker that performs an intermittent random walk, characterized by different states of motion. In addition, we assume that the walker has the ability to detect the scent left by the prey/target in its surroundings. Our results, in agreement with intuition, indicate that the prey's survival probability could be strongly reduced (increased) if the predator is attracted (or repelled) by the trace left by the prey. We have also found that, for a positive trace (the predator is guided towards the prey), increasing the inhomogeneity's size reduces the prey's survival probability, while the optimal value of {alpha} (the parameter that regulates intermittency) ceases to exist. The agreement between theory and numerical simulations is excellent.

  16. Optimal Dynamics of Intermittent Water Supply

    Science.gov (United States)

    Lieb, Anna; Wilkening, Jon; Rycroft, Chris

    2014-11-01

    In many urban areas of the developing world, piped water is supplied only intermittently, as valves direct water to different parts of the water distribution system at different times. The flow is transient, and may transition between free-surface and pressurized, resulting in complex dynamical features with important consequences for water suppliers and users. These consequences include degradation of distribution system components, compromised water quality, and inequitable water availability. The goal of this work is to model the important dynamics and identify operating conditions that mitigate certain negative effects of intermittent water supply. Specifically, we will look at valve parameters occurring as boundary conditions in a network model of transient, transition flow through closed pipes. Optimization will be used to find boundary values to minimize pressure gradients and ensure equitable water availability.

  17. AN ELDERLY WOMAN WITH INTERMITTENT CLAUDICATION

    Directory of Open Access Journals (Sweden)

    Nayyer Naveed Wazir

    2006-01-01

    Full Text Available This case report illustrates the misdiagnosis of intermittent claudication in an elderly with multiple cardiac risk factors. Careful clinical evaluation and imaging shifts the diagnosis from peripheral vascular disease to spinal stenosis. The decision whether to offer conservative therapy or proceed to spinal surgery requires an accurate assessment of the severity of the symptoms without ignoring the important role of patient preferences.

  18. Long-range forecasting of intermittent streamflow

    OpenAIRE

    F. F. van Ogtrop; R. W. Vervoort; G. Z. Heller; D. M. Stasinopoulos; R. A. Rigby

    2011-01-01

    Long-range forecasting of intermittent streamflow in semi-arid Australia poses a number of major challenges. One of the challenges relates to modelling zero, skewed, non-stationary, and non-linear data. To address this, a statistical model to forecast streamflow up to 12 months ahead is applied to five semi-arid catchments in South Western Queensland. The model uses logistic regression through Generalised Additive Models for Location, Scale and Shape (GAMLSS) to determine th...

  19. Long-range forecasting of intermittent streamflow

    OpenAIRE

    F. F. van Ogtrop; R. W. Vervoort; G. Z. Heller; D. M. Stasinopoulos; R. A. Rigby

    2011-01-01

    Long-range forecasting of intermittent streamflow in semi-arid Australia poses a number of major challenges. One of the challenges relates to modelling zero, skewed, non-stationary, and non-linear data. To address this, a probabilistic statistical model to forecast streamflow 12 months ahead is applied to five semi-arid catchments in South Western Queensland. The model uses logistic regression through Generalised Additive Models for Location, Scale and Shape (GAMLSS) to determine the probabil...

  20. Evaluation of stream crossing methods prior to gas pipeline construction

    International Nuclear Information System (INIS)

    Murphy, M.H.; Rogers, J.S.; Ricca, A.

    1995-01-01

    Stream surveys are conducted along proposed gas pipeline routes prior to construction to assess potential impacts to stream ecosystems and to recommend preferred crossing methods. Recently, there has been a high level of scrutiny from the Public Service Commission (PSC) to conduct these stream crossings with minimal effects to the aquatic community. PSC's main concern is the effect of sediment on aquatic biota. Smaller, low flowing or intermittent streams are generally crossed using a wet crossing technique. This technique involves digging a trench for the pipeline while the stream is flowing. Sediment control measures are used to reduce sediment loads downstream. Wider, faster flowing, or protected streams are typically crossed with a dry crossing technique. A dry crossing involves placing a barrier upstream of the crossing and diverting the water around the crossing location. The pipeline trench is then dug in the dry area. O'Brien and Gere and NYSEG have jointly designed a modified wet crossing for crossing streams that exceed maximum flows for a dry crossing, and are too wide for a typical wet crossing. This method diverts water around the crossing using a pumping system, instead of constructing a dam. The trench is similar to a wet crossing, with sediment control devices in place upstream and downstream. If streams are crossed during low flow periods, the pumping system will be able to reduce the majority of water flow and volume form the crossing area, thereby reducing ecological impacts. Evaluation of effects of this crossing type on the stream biota are currently proposed and may proceed when construction begins

  1. Soil plutonium and cesium in stream channels and banks of Los Alamos liquid effluent-receiving areas

    International Nuclear Information System (INIS)

    Nyhan, J.W.; White, G.C.; Trujillo, G.

    1982-01-01

    Stream channel sediments and adjacent bank soils found in three intermittent streams used for treated liquid effluent disposal at Los Alamos, New Mexico were sampled to determine the distribution of 238 Pu, sup(239,240)Pu and 137 Cs. Radionuclide concentrations and inventories were determined as functions of distance downstream from the waste outfall and from the center of the stream channel, soil sampling depth, stream channel-bank physiography, and the waste use history of each disposal area. Radionuclide concentrations in channel sediments were inversely related to distances up to 10 km downstream from the outfalls. For sites receiving appreciable waste effluent additions, contaminant concentrations in bank soils decreased with perpendicular distances greater than 0.38 m from the stream channel, and with stream bank sampling depths greater than 20-40 cm. Concentrations and total inventories of radionuclides in stream bank soils generally decreased as stream bank height increased. Inventory estimates of radionuclides in channel sediments exhibited coefficients of variation that ranged 0.41-2.6, reflecting the large variation in radionuclide concentrations at each site. Several interesting temporal relationships of these radionuclides in intermittent streams were gleaned from the varying waste use histories of the three effluent-receiving areas. Eleven years after liquid wastes were added to one canyon, the major radionuclide inventories were found in the stream bank soils, unlike most of the other currently-used receiving areas. A period of time greater than 6 yr seems to be required before the plutonium in liquid wastes currently added to the canyon is approximately equilibrated with the plutonium in the bank soils. These observations are discussed relative to waste management practices in these southwestern intermittent streams. (author)

  2. Soil plutonium and cesium in stream channels and banks of Los Alamos liquid effluent-receiving areas.

    Science.gov (United States)

    Nyhan, J W; White, G C; Trujillo, G

    1982-10-01

    Stream channel sediments and adjacent bank soils found in three intermittent streams used for treated liquid effluent disposal at Los Alamos, New Mexico were sampled to determine the distribution of 238Pu, 239,240Pu and 137Cs. Radionuclide concentrations and inventories were determined as functions of distance downstream from the waste outfall and from the center of the stream channel, soil sampling depth, stream channel-bank physiography, and the waste use history of each disposal area. Radionuclide concentrations in channel sediments were inversely related to distances up to 10 km downstream from the outfalls. For sites receiving appreciable waste effluent additions, contaminant concentrations in bank soils decreased with perpendicular distances greater than 0.38 m from the stream channel, and with stream bank sampling depths greater than 20-40 cm. Concentrations and total inventories of radionuclides in stream bank soils generally decreased as stream bank height increased. Inventory estimates of radionuclides in channel sediments exhibited coefficients of variation that ranged 0.41-2.6, reflecting the large variation in radionuclide concentrations at each site. Several interesting temporal relationships of these radionuclides in intermittent streams were gleaned from the varying waste use histories of the three effluent-receiving areas. Eleven yr after liquid wastes were added to one canyon, the major radionuclide inventories were found in the stream bank soils, unlike most of the other currently-used receiving areas. A period of time greater than 6 yr seems to be required before the plutonium in liquid wastes currently added to the canyon is approximately equilibrated with the plutonium in the bank soils. These observations are discussed relative to waste management practices in these southwestern intermittent streams.

  3. Efficient search by optimized intermittent random walks

    International Nuclear Information System (INIS)

    Oshanin, Gleb; Lindenberg, Katja; Wio, Horacio S; Burlatsky, Sergei

    2009-01-01

    We study the kinetics for the search of an immobile target by randomly moving searchers that detect it only upon encounter. The searchers perform intermittent random walks on a one-dimensional lattice. Each searcher can step on a nearest neighbor site with probability α or go off lattice with probability 1 - α to move in a random direction until it lands back on the lattice at a fixed distance L away from the departure point. Considering α and L as optimization parameters, we seek to enhance the chances of successful detection by minimizing the probability P N that the target remains undetected up to the maximal search time N. We show that even in this simple model, a number of very efficient search strategies can lead to a decrease of P N by orders of magnitude upon appropriate choices of α and L. We demonstrate that, in general, such optimal intermittent strategies are much more efficient than Brownian searches and are as efficient as search algorithms based on random walks with heavy-tailed Cauchy jump-length distributions. In addition, such intermittent strategies appear to be more advantageous than Levy-based ones in that they lead to more thorough exploration of visited regions in space and thus lend themselves to parallelization of the search processes.

  4. Testing a community water supply well located near a stream for susceptibility to stream contamination and low-flows.

    Science.gov (United States)

    Stewart-Maddox, N. S.; Tysor, E. H.; Swanson, J.; Degon, A.; Howard, J.; Tsinnajinnie, L.; Frisbee, M. D.; Wilson, J. L.; Newman, B. D.

    2014-12-01

    A community well is the primary water supply to the town of El Rito. This small rural town in is located in a semi-arid, mountainous portion of northern New Mexico where water is scarce. The well is 72 meters from a nearby intermittent stream. Initial tritium sampling suggests a groundwater connection between the stream and well. The community is concerned with the sustainability and future quality of the well water. If this well is as tightly connected to the stream as the tritium data suggests, then the well is potentially at risk due to upstream contamination and the impacts of extended drought. To examine this, we observed the well over a two-week period performing pump and recovery tests, electrical resistivity surveys, and physical observations of the nearby stream. We also collected general chemistry, stable isotope and radon samples from the well and stream. Despite the large well diameter, our pump test data exhibited behavior similar to a Theis curve, but the rate of drawdown decreased below the Theis curve late in the test. This decrease suggests that the aquifer is being recharged, possibly through delayed yield, upwelling of groundwater, or from the stream. The delayed yield hypothesis is supported by our electrical resistivity surveys, which shows very little change in the saturated zone over the course of the pump test, and by low values of pump-test estimated aquifer storativity. Observations of the nearby stream showed no change in stream-water level throughout the pump test. Together this data suggests that the interaction between the stream and the well is low, but recharge could be occurring through other mechanisms such as delayed yield. Additional pump tests of longer duration are required to determine the exact nature of the aquifer and its communication with the well.

  5. LHCb trigger streams optimization

    Science.gov (United States)

    Derkach, D.; Kazeev, N.; Neychev, R.; Panin, A.; Trofimov, I.; Ustyuzhanin, A.; Vesterinen, M.

    2017-10-01

    The LHCb experiment stores around 1011 collision events per year. A typical physics analysis deals with a final sample of up to 107 events. Event preselection algorithms (lines) are used for data reduction. Since the data are stored in a format that requires sequential access, the lines are grouped into several output file streams, in order to increase the efficiency of user analysis jobs that read these data. The scheme efficiency heavily depends on the stream composition. By putting similar lines together and balancing the stream sizes it is possible to reduce the overhead. We present a method for finding an optimal stream composition. The method is applied to a part of the LHCb data (Turbo stream) on the stage where it is prepared for user physics analysis. This results in an expected improvement of 15% in the speed of user analysis jobs, and will be applied on data to be recorded in 2017.

  6. A wavelet-based intermittency detection technique from PIV investigations in transitional boundary layers

    Science.gov (United States)

    Simoni, Daniele; Lengani, Davide; Guida, Roberto

    2016-09-01

    The transition process of the boundary layer growing over a flat plate with pressure gradient simulating the suction side of a low-pressure turbine blade and elevated free-stream turbulence intensity level has been analyzed by means of PIV and hot-wire measurements. A detailed view of the instantaneous flow field in the wall-normal plane highlights the physics characterizing the complex process leading to the formation of large-scale coherent structures during breaking down of the ordered motion of the flow, thus generating randomized oscillations (i.e., turbulent spots). This analysis gives the basis for the development of a new procedure aimed at determining the intermittency function describing (statistically) the transition process. To this end, a wavelet-based method has been employed for the identification of the large-scale structures created during the transition process. Successively, a probability density function of these events has been defined so that an intermittency function is deduced. This latter strictly corresponds to the intermittency function of the transitional flow computed trough a classic procedure based on hot-wire data. The agreement between the two procedures in the intermittency shape and spot production rate proves the capability of the method in providing the statistical representation of the transition process. The main advantages of the procedure here proposed concern with its applicability to PIV data; it does not require a threshold level to discriminate first- and/or second-order time-derivative of hot-wire time traces (that makes the method not influenced by the operator); and it provides a clear evidence of the connection between the flow physics and the statistical representation of transition based on theory of turbulent spot propagation.

  7. Asteroid/meteorite streams

    Science.gov (United States)

    Drummond, J.

    The independent discovery of the same three streams (named alpha, beta, and gamma) among 139 Earth approaching asteroids and among 89 meteorite producing fireballs presents the possibility of matching specific meteorites to specific asteroids, or at least to asteroids in the same stream and, therefore, presumably of the same composition. Although perhaps of limited practical value, the three meteorites with known orbits are all ordinary chondrites. To identify, in general, the taxonomic type of the parent asteroid, however, would be of great scientific interest since these most abundant meteorite types cannot be unambiguously spectrally matched to an asteroid type. The H5 Pribram meteorite and asteroid 4486 (unclassified) are not part of a stream, but travel in fairly similar orbits. The LL5 Innisfree meteorite is orbitally similar to asteroid 1989DA (unclassified), and both are members of a fourth stream (delta) defined by five meteorite-dropping fireballs and this one asteroid. The H5 Lost City meteorite is orbitally similar to 1980AA (S type), which is a member of stream gamma defined by four asteroids and four fireballs. Another asteroid in this stream is classified as an S type, another is QU, and the fourth is unclassified. This stream suggests that ordinary chondrites should be associated with S (and/or Q) asteroids. Two of the known four V type asteroids belong to another stream, beta, defined by five asteroids and four meteorite-dropping (but unrecovered) fireballs, making it the most probable source of the eucrites. The final stream, alpha, defined by five asteroids and three fireballs is of unknown composition since no meteorites have been recovered and only one asteroid has an ambiguous classification of QRS. If this stream, or any other as yet undiscovered ones, were found to be composed of a more practical material (e.g., water or metalrich), then recovery of the associated meteorites would provide an opportunity for in-hand analysis of a potential

  8. Impacts of habitat degradation and stream spatial location on biodiversity in a disturbed riverine landscape

    DEFF Research Database (Denmark)

    Göthe, Emma; Wiberg-Larsen, Peter; Kristensen, Esben Astrup

    2015-01-01

    gradients. We used macrophyte, fish and macroinvertebrate data from Danish lowland streams to investigate whether (1) high connectivity in reaches situated in lower parts of the stream network (downstream sites) generates high α-diversity, while dispersal limitation and high habitat heterogeneity across......The ongoing degradation of freshwater habitat quality and subsequent losses of biodiversity is alarming. One key to successful freshwater management is to understand how different scale-dependent diversity components (i.e. γ-, α- and β-diversity) change along present-day anthropogenic impact...... the more isolated upper reaches (headwater sites) generate high β-diversity, (2) γ-, α- and β- diversity decrease with increasing hydromorphological impact and (3) high connectivity in downstream reaches buffers against impacts on biodiversity. Results showed that α-diversity was higher in downstream sites...

  9. Evidence for acid-precipitation-induced trends in stream chemistry at hydrologic bench-mark stations

    Science.gov (United States)

    Smith, Richard A.; Alexander, Richard B.

    1983-01-01

    Ten- to 15-year water-quality records from a network of headwater sampling stations show small declines in stream sulfate concentrations at stations in the northeastern quarter of the Nation and small increases in sulfate at most southeastern and western sites. The regional pattern of stream sulfate trends is similar to that reported for trends in S02 emissions to the atmosphere during the same period. Trends in the ratio of alkalinity to total major cation concentrations at the stations follow an inverse pattern of small increases in the Northeast and small, but widespread decreases elsewhere. The undeveloped nature of the sampled basins and the magnitude and direction of observed changes in relation to SO2 emissions support the hypothesis that the observed patterns in water quality trends reflect regional changes in the rates of acid deposition.

  10. The influence of data characteristics on detecting wetland/stream surface-water connections in the Delmarva Peninsula, Maryland and Delaware

    Science.gov (United States)

    Vanderhoof, Melanie; Distler, Hayley; Lang, Megan W.; Alexander, Laurie C.

    2018-01-01

    The dependence of downstream waters on upstream ecosystems necessitates an improved understanding of watershed-scale hydrological interactions including connections between wetlands and streams. An evaluation of such connections is challenging when, (1) accurate and complete datasets of wetland and stream locations are often not available and (2) natural variability in surface-water extent influences the frequency and duration of wetland/stream connectivity. The Upper Choptank River watershed on the Delmarva Peninsula in eastern Maryland and Delaware is dominated by a high density of small, forested wetlands. In this analysis, wetland/stream surface water connections were quantified using multiple wetland and stream datasets, including headwater streams and depressions mapped from a lidar-derived digital elevation model. Surface-water extent was mapped across the watershed for spring 2015 using Landsat-8, Radarsat-2 and Worldview-3 imagery. The frequency of wetland/stream connections increased as a more complete and accurate stream dataset was used and surface-water extent was included, in particular when the spatial resolution of the imagery was finer (i.e., watershed contributing direct surface water runoff to streamflow. This finding suggests that our interpretation of the frequency and duration of wetland/stream connections will be influenced not only by the spatial and temporal characteristics of wetlands, streams and potential flowpaths, but also by the completeness, accuracy and resolution of input datasets.

  11. Percent Forest Adjacent to Streams

    Data.gov (United States)

    U.S. Environmental Protection Agency — The type of vegetation along a stream influences the water quality in the stream. Intact buffer strips of natural vegetation along streams tend to intercept...

  12. Percent Agriculture Adjacent to Streams

    Data.gov (United States)

    U.S. Environmental Protection Agency — The type of vegetation along a stream influences the water quality in the stream. Intact buffer strips of natural vegetation along streams tend to intercept...

  13. Transition over C4 leading edge and measurement of intermittency factor using PDF of hot-wire signal

    Energy Technology Data Exchange (ETDEWEB)

    Hazarika, B.K.; Hirsch, C. [Vrije Univ. Brussel, Brussels (Belgium). Dept. of Fluid Mechanics

    1997-07-01

    The variation of intermittency factors in the transition region of a C4 leading edge flat plate is measured at three incidence angles in a low-turbulence free stream. During the determination of intermittency factor, the threshold value of the detector function and the validity of conditional averaging are verified by a method based on the direct application of PDF of the hot-wire output. As the angle of incidence is increased, the transition progressively moves through all the three modes on the suction surface: at zero incidence the bypass transition, at 2 deg incidence the natural transition, and at 4 deg incidence the separated-flow transition occur, respectively. All three modes of transition exhibited the chordwise intermittency factor variation in accordance with Narasinha`s universal intermittency distribution; thus, the method based on spot production rate is applicable to all the three modes of transition. In the transition zone of the attached boundary layers, the conditionally averaged interturbulent profiles are fuller than the Blasius profile, while the conditionally averaged turbulent profiles follow a logarithmic profile with a variable additive parameter.

  14. Composition and structure of fish assemblage from Passa Cinco stream, Corumbataí river sub-basin, SP, Brazil

    Directory of Open Access Journals (Sweden)

    AL Carmassi

    Full Text Available The aim of this work was to determine the composition of the fish assemblage of Passa Cinco stream and verify changes in their structure on the altitudinal gradient. Six samples were performed at five different sites in Passa Cinco stream (from the headwater, at order two, to its mouth, at order six, using an electric fishery equipment and gill nets in May, July, September and November of 2005 and January and March of 2006. The indices of Shannon's diversity, Pielou's evenness and Margalef's richness were quantified separately considering the different fishery equipment (nets versus electric fishery equipment. An ANOVA was used to compare samples collected in relation to values of abundance, diversity, evenness and richness. The representativeness of the species was summarised by their average values of abundance and weight. We captured 5082 individuals distributed into 61 species. We observed a trend of increasing diversity, richness and evenness of species from site 1 to 3, with further decrease in sites 4 and 5. The values found for habitat diversity also followed this pattern. Significant differences were found for all three indices considering the electric fishery samples. For individuals caught with nets, only the richness index showed a significant difference. Characidium aff. zebra was an important species in the headwater and transition sites and Hypostomus strigaticeps in middle-lower course sites. Despite the small extension of the Passa Cinco stream, environments structurally well defined were evidenced by the species distribution and assemblage composition along the gradient.

  15. Determinants of fish assemblage structure in Northwestern Great Plains streams

    Science.gov (United States)

    Mullen, J.A.; Bramblett, R.G.; Guy, C.S.; Zale, A.V.; Roberts, D.W.

    2011-01-01

    Prairie streams are known for their harsh and stochastic physical conditions, and the fish assemblages therein have been shown to be temporally variable. We assessed the spatial and temporal variation in fish assemblage structure in five intermittent, adventitious northwestern Great Plains streams representing a gradient of watershed areas. Fish assemblages and abiotic conditions varied more spatially than temporally. The most important variables explaining fish assemblage structure were longitudinal position and the proportion of fine substrates. The proportion of fine substrates increased proceeding upstream, approaching 100% in all five streams, and species richness declined upstream with increasing fine substrates. High levels of fine substrate in the upper reaches appeared to limit the distribution of obligate lithophilic fish species to reaches further downstream. Species richness and substrates were similar among all five streams at the lowermost and uppermost sites. However, in the middle reaches, species richness increased, the amount of fine substrate decreased, and connectivity increased as watershed area increased. Season and some dimensions of habitat (including thalweg depth, absolute distance to the main-stem river, and watershed size) were not essential in explaining the variation in fish assemblages. Fish species richness varied more temporally than overall fish assemblage structure did because common species were consistently abundant across seasons, whereas rare species were sometimes absent or perhaps not detected by sampling. The similarity in our results among five streams varying in watershed size and those from other studies supports the generalization that spatial variation exceeds temporal variation in the fish assemblages of prairie and warmwater streams. Furthermore, given longitudinal position, substrate, and stream size, general predictions regarding fish assemblage structure and function in prairie streams are possible. ?? American

  16. Wadeable Streams Assessment Data

    Science.gov (United States)

    The Wadeable Streams Assessment (WSA) is a first-ever statistically-valid survey of the biological condition of small streams throughout the U.S. The U.S. Environmental Protection Agency (EPA) worked with the states to conduct the assessment in 2004-2005. Data for each parameter sampled in the Wadeable Streams Assessment (WSA) are available for downloading in a series of files as comma separated values (*.csv). Each *.csv data file has a companion text file (*.txt) that lists a dataset label and individual descriptions for each variable. Users should view the *.txt files first to help guide their understanding and use of the data.

  17. AN INVESTIGATION INTO THE DISAPPEARANCE OF AUSTROPOTAMOBIUS PALLIPES (LEREBOULLET POPULATIONS IN THE HEADWATERS OF THE NORE RIVER, IRELAND AND THE CORRELATION TO WATER QUALITY

    Directory of Open Access Journals (Sweden)

    LYONS R.

    2003-04-01

    Full Text Available Monitoring of the protected white-clawed crayfish Austropotamobius pallipes (Lereboullet has been carried out in the headwaters of the Nore River since 1995. In recent years a reduction in crayfish abundance had become apparent. Some populations had completely disappeared. Adult crayfish were sampled using the baited trap method while juveniles were sampled using a modified surber sampler. The temporal variation in baited trap data was found to be significant at three of the sites while significant variation in enclosure sampling data was found at two sites. In an effort to ascertain why the populations had disappeared a possible relationship between water quality and adult and juvenile crayfish numbers was investigated. Water quality was assessed using both chemical and macroinvertebrate data. Macroinvertebrate sampling revealed deterioration in water quality at all sites. Results also showed the disappearance of crayfish from both Q3 and Q3-4 waters at some sites yet crayfish remain at these Q-ratings at other sites. Therefore the Q-rating below which crayfish cannot survive cannot clearly be defined. However, no clear correlation was observed between the water chemistry data and the crayfish data. Crayfish populations at the Fertagh (FRT site appear to be surviving intermittent pollution and eutrophic conditions where pre-dawn oxygen sags reach lows of 4.4 mg/l O2. Deterioration in water quality as indicated by the Q-value biotic index coincided with reduced crayfish catches. There is no evidence to suggest that predation be it of aquatic or terrestrial origin is a major contributing factor.

  18. Hovering and intermittent flight in birds

    International Nuclear Information System (INIS)

    Tobalske, Bret W

    2010-01-01

    Two styles of bird locomotion, hovering and intermittent flight, have great potential to inform future development of autonomous flying vehicles. Hummingbirds are the smallest flying vertebrates, and they are the only birds that can sustain hovering. Their ability to hover is due to their small size, high wingbeat frequency, relatively large margin of mass-specific power available for flight and a suite of anatomical features that include proportionally massive major flight muscles (pectoralis and supracoracoideus) and wing anatomy that enables them to leave their wings extended yet turned over (supinated) during upstroke so that they can generate lift to support their weight. Hummingbirds generate three times more lift during downstroke compared with upstroke, with the disparity due to wing twist during upstroke. Much like insects, hummingbirds exploit unsteady mechanisms during hovering including delayed stall during wing translation that is manifest as a leading-edge vortex (LEV) on the wing and rotational circulation at the end of each half stroke. Intermittent flight is common in small- and medium-sized birds and consists of pauses during which the wings are flexed (bound) or extended (glide). Flap-bounding appears to be an energy-saving style when flying relatively fast, with the production of lift by the body and tail critical to this saving. Flap-gliding is thought to be less costly than continuous flapping during flight at most speeds. Some species are known to shift from flap-gliding at slow speeds to flap-bounding at fast speeds, but there is an upper size limit for the ability to bound (∼0.3 kg) and small birds with rounded wings do not use intermittent glides.

  19. Hovering and intermittent flight in birds

    Energy Technology Data Exchange (ETDEWEB)

    Tobalske, Bret W, E-mail: bret.tobalske@mso.umt.ed [Field Research Station at Fort Missoula, Division of Biological Sciences, University of Montana, Missoula, MT 59812 (United States)

    2010-12-15

    Two styles of bird locomotion, hovering and intermittent flight, have great potential to inform future development of autonomous flying vehicles. Hummingbirds are the smallest flying vertebrates, and they are the only birds that can sustain hovering. Their ability to hover is due to their small size, high wingbeat frequency, relatively large margin of mass-specific power available for flight and a suite of anatomical features that include proportionally massive major flight muscles (pectoralis and supracoracoideus) and wing anatomy that enables them to leave their wings extended yet turned over (supinated) during upstroke so that they can generate lift to support their weight. Hummingbirds generate three times more lift during downstroke compared with upstroke, with the disparity due to wing twist during upstroke. Much like insects, hummingbirds exploit unsteady mechanisms during hovering including delayed stall during wing translation that is manifest as a leading-edge vortex (LEV) on the wing and rotational circulation at the end of each half stroke. Intermittent flight is common in small- and medium-sized birds and consists of pauses during which the wings are flexed (bound) or extended (glide). Flap-bounding appears to be an energy-saving style when flying relatively fast, with the production of lift by the body and tail critical to this saving. Flap-gliding is thought to be less costly than continuous flapping during flight at most speeds. Some species are known to shift from flap-gliding at slow speeds to flap-bounding at fast speeds, but there is an upper size limit for the ability to bound ({approx}0.3 kg) and small birds with rounded wings do not use intermittent glides.

  20. Water flow pathways and the water balance within a head-water catchment containing a dambo: inferences drawn from hydrochemical investigations

    Directory of Open Access Journals (Sweden)

    M. P. McCartney

    1999-01-01

    Full Text Available Dambos, seasonally saturated wetlands, are widespread in headwater catchments in sub-Saharan Africa. It is widely believed that they play an important role in regional hydrology but, despite research conducted over the last 25 years, their hydrological functions remain poorly understood. To improve conceptualisation of hydrological flow paths and investigate the water balance of a small Zimbabwean catchment containing a single dambo, measurements of alkalinity and chloride in different water types within the catchment have been used as chemical markers. The temporal variation in alkalinity is consistent with the premise that all stream water, including the prolonged dry season recession, is derived predominantly from shallow sources. The proposition that dry season recession flows are maintained by water travelling at depth within the underlying saprolite is not substantiated. There is evidence that a low permeability clay lens, commonly present in many dambos, acts as a barrier for vertical water exchange. However, the highly heterogeneous chemical composition of different waters precludes quantitative hydrograph split-ting using end member mixing analysis. Calculation of the chloride mass-balance confirms that, after rainfall, evaporation is the largest component of the catchment water budget. The study provides improved understanding of the hydrological functioning of dambos. Such understanding is essential for the development and implementation of sustainable management strategies for this landform.

  1. Renewable energies: the cost of intermittency

    International Nuclear Information System (INIS)

    Crassous, Renaud; Roques, Fabien

    2013-01-01

    The authors indicate the different adaptations which will be required for the electric system to cope with the intermittency of solar and wind energy production, and propose an approximate assessment of the associated costs. Different types of adaptation are addressed: secure production in case of absence of wind or sun (electricity imports, construction of additional power stations), use of more flexible production means (gas turbines), grid extensions (connection to offshore production sites, routing of production one part of the country to the other). They think that beyond a 20 per cent share for renewable energies, these costs could rapidly increase

  2. Spatio-temporal intermittency on the sandpile

    International Nuclear Information System (INIS)

    Erzan, A.; Sinha, S.

    1990-08-01

    The self-organized critical state exhibited by a sandpile model is shown to correspond to motion on an attractor characterized by an invariant distribution of the height variable. The largest Lyapunov exponent is equal to zero. The model nonetheless displays intermittent chaos, with a multifractal distribution of local expansion coefficients in history space. Laminar spatio-temporal regions are interrupted by chaotic bursts caused by avalanches. We introduce the concept of local histories in configuration space and show that their expansion parameters also exhibit a multifractal distribution in time and space. (author). 22 refs, 5 figs

  3. Intermittent claudication in a professional rugby player.

    Science.gov (United States)

    Bray, A E; Lewis, W A

    1992-04-01

    Intermittent claudication in a professional rugby player is described. The typical features of a delayed and difficult diagnosis of an external iliac artery stenosis were found. The noninvasive diagnostic protocol used to investigate this young patient with a minimal arterial lesion enabled accurate localization and angioplasty to be performed at the same time as diagnostic angiography. The patient was symptom free with normal arterial pressures on follow-up. It is suggested that appropriate noninvasive investigations should be performed before angiography in young people with minimal lesions.

  4. A stochastic model for intermittent search strategies

    International Nuclear Information System (INIS)

    Benichou, O; Coppey, M; Moreau, M; Suet, P H; Voituriez, R

    2005-01-01

    It is often necessary, in scientific or everyday life problems, to find a randomly hidden target. What is then the optimal strategy to reach it as rapidly as possible? In this article, we develop a stochastic theory for intermittent search behaviours, which are often observed: the searcher alternates phases of intensive search and slow motion with fast displacements. The first results of this theory have already been announced recently. Here we provide a detailed presentation of the theory, as well as the full derivation of the results. Furthermore, we explicitly discuss the minimization of the time needed to find the target

  5. Intermittent oral iron supplementation during pregnancy (Review)

    Science.gov (United States)

    Peña-Rosas, Juan Pablo; De-Regil, Luz Maria; Dowswell, Therese; Viteri, Fernando E

    2014-01-01

    Background Anaemia is a frequent condition during pregnancy, particularly among women from developing countries who have insufficient iron intake to meet increased iron needs of both the mother and the fetus. Traditionally, gestational anaemia has been prevented with the provision of daily iron supplements throughout pregnancy, but adherence to this regimen due to side effects, interrupted supply of the supplements, and concerns about safety among women with an adequate iron intake, have limited the use of this intervention. Intermittent (i.e. one, two or three times a week on non-consecutive days) supplementation with iron alone or in combination with folic acid or other vitamins and minerals has recently been proposed as an alternative to daily supplementation. Objectives To assess the benefits and harms of intermittent supplementation with iron alone or in combination with folic acid or other vitamins and minerals to pregnant women on neonatal and pregnancy outcomes. Search methods We searched the Cochrane Pregnancy and Childbirth Group’s Trials Register (23 March 2012). We also searched the WHO International Clinical Trials Registry Platform (ICTRP) for ongoing studies and contacted relevant organisations for the identification of ongoing and unpublished studies (23 March 2012). Selection criteria Randomised or quasi-randomised trials. Data collection and analysis We assessed the methodological quality of trials using standard Cochrane criteria. Two review authors independently assessed trial eligibility, extracted data and conducted checks for accuracy. Main results This review includes 21 trials from 13 different countries, but only 18 trials (with 4072 women) reported on our outcomes of interest and contributed data to the review. All of these studies compared daily versus intermittent iron supplementation. Three studies provided iron alone, 12 iron+folic acid and three more iron plus multiple vitamins and minerals. Their methodological quality was mixed

  6. Estimating occurrence and detection probabilities for stream-breeding salamanders in the Gulf Coastal Plain

    Science.gov (United States)

    Lamb, Jennifer Y.; Waddle, J. Hardin; Qualls, Carl P.

    2017-01-01

    Large gaps exist in our knowledge of the ecology of stream-breeding plethodontid salamanders in the Gulf Coastal Plain. Data describing where these salamanders are likely to occur along environmental gradients, as well as their likelihood of detection, are important for the prevention and management of amphibian declines. We used presence/absence data from leaf litter bag surveys and a hierarchical Bayesian multispecies single-season occupancy model to estimate the occurrence of five species of plethodontids across reaches in headwater streams in the Gulf Coastal Plain. Average detection probabilities were high (range = 0.432–0.942) and unaffected by sampling covariates specific to the use of litter bags (i.e., bag submergence, sampling season, in-stream cover). Estimates of occurrence probabilities differed substantially between species (range = 0.092–0.703) and were influenced by the size of the upstream drainage area and by the maximum proportion of the reach that dried. The effects of these two factors were not equivalent across species. Our results demonstrate that hierarchical multispecies models successfully estimate occurrence parameters for both rare and common stream-breeding plethodontids. The resulting models clarify how species are distributed within stream networks, and they provide baseline values that will be useful in evaluating the conservation statuses of plethodontid species within lotic systems in the Gulf Coastal Plain.

  7. Effects of microhabitat and land use on stream salamander abundance in the southwest Virginia coalfields

    Science.gov (United States)

    Sweeten, Sara E.; Ford, W. Mark

    2015-01-01

    Large-scale land uses such as residential wastewater discharge and coal mining practices, particularly surface coal extraction and associated valley fills, are of particular ecological concern in central Appalachia. Identification and quantification of both alterations across scales are a necessary first-step to mitigate negative consequences to biota. In central Appalachian headwater streams absent of fish, salamanders are the dominant, most abundant vertebrate predator providing a significant intermediate trophic role. Stream salamander species are considered to be sensitive to aquatic stressors and environmental alterations, and past research has shown linkages among microhabitat parameters, large-scale land use such as urbanization and logging with salamander abundances. However, little is known about these linkages in the coalfields of central Appalachia. In the summer of 2013, we visited 70 sites (sampled three times each) in the southwest Virginia coalfields to survey salamanders and quantify stream and riparian microhabitat parameters. Using an information-theoretic framework we compared the effects of microhabitat and large-scale land use on salamander abundances. Our findings indicate that dusky salamander (Desmognathus spp.) abundances are more correlated to microhabitat parameters such as canopy cover than to subwatershed land uses. Brook salamander (Eurycea spp.) abundances show strong negative associations to the suspended sediments and stream substrate embeddedness. Neither Desmognathus spp. nor Eurycea spp. abundances were influenced by water conductivity. These suggest protection or restoration of riparian habitats and erosion control is an important conservation component for maintaining stream salamanders in the mined landscapes of central Appalachia.

  8. Influences on wood load in mountain streams of the Bighorn National Forest, Wyoming, USA.

    Science.gov (United States)

    Nowakowski, Amy L; Wohl, Ellen

    2008-10-01

    We documented valley and channel characteristics and wood loads in 19 reaches of forested headwater mountain streams in the Bighorn National Forest of northern Wyoming. Ten of these reaches were in the Upper Tongue River watershed, which has a history of management including timber harvest, tie floating, and road construction. Nine reaches were in the North Rock Creek watershed, which has little history of management activities. We used these data to test hypotheses that (i) valley geometry correlates with wood load, (ii) stream gradient correlates with wood load, and (iii) wood loads are significantly lower in managed watersheds than in otherwise similar unmanaged watersheds. Statistical analyses of the data support the first and third hypotheses. Stream reaches with steeper valley side slopes tend to have higher wood loads, and reaches in managed watersheds tend to have lower wood loads than reaches in unmanaged watersheds. Results do not support the second hypothesis. Shear stress correlated more strongly with wood load than did stream gradient, but statistical models with valley-scale variables had greater explanatory power than statistical models with channel-scale variables. Wood loads in stream reaches within managed watersheds in the Bighorn National Forest tend to be two to three times lower than wood loads in unmanaged watersheds.

  9. Intermittent fasting and cardiovascular disease: current evidence and unresolved questions.

    Science.gov (United States)

    Tinsley, Grant M; Horne, Benjamin D

    2018-01-01

    Intermittent fasting has produced a variety of beneficial health effects in animal models, although high-quality research in humans has been limited. This special report examines current evidences for intermittent fasting in humans, discusses issues that require further examination, and recommends new research that can improve the knowledge base in this emerging research area. While potentially useful for health improvement, intermittent fasting requires further study prior to widespread implementation for health purposes. Randomized, longer-term studies are needed to determine whether using intermittent fasting as a lifestyle rather than a diet is feasible and beneficial for the health of some members of the human population.

  10. Atomistic Model of Fluorescence Intermittency of Colloidal Quantum Dots

    KAUST Repository

    Voznyy, O.; Sargent, E. H.

    2014-01-01

    with foreign cations can stabilize the vacancies, inhibiting intermittency and improving quantum yield, providing an explanation of recent experimental observations. © 2014 American Physical Society.

  11. Future Roads Near Streams

    Data.gov (United States)

    U.S. Environmental Protection Agency — Roads are a source of auto related pollutants (e.g. gasoline, oil and other engine fluids). When roads are near streams, rain can wash these pollutants directly into...

  12. Channelized Streams in Iowa

    Data.gov (United States)

    Iowa State University GIS Support and Research Facility — This draft dataset consists of all ditches or channelized pieces of stream that could be identified using three input datasets; namely the1:24,000 National...

  13. Stochastic ice stream dynamics.

    Science.gov (United States)

    Mantelli, Elisa; Bertagni, Matteo Bernard; Ridolfi, Luca

    2016-08-09

    Ice streams are narrow corridors of fast-flowing ice that constitute the arterial drainage network of ice sheets. Therefore, changes in ice stream flow are key to understanding paleoclimate, sea level changes, and rapid disintegration of ice sheets during deglaciation. The dynamics of ice flow are tightly coupled to the climate system through atmospheric temperature and snow recharge, which are known exhibit stochastic variability. Here we focus on the interplay between stochastic climate forcing and ice stream temporal dynamics. Our work demonstrates that realistic climate fluctuations are able to (i) induce the coexistence of dynamic behaviors that would be incompatible in a purely deterministic system and (ii) drive ice stream flow away from the regime expected in a steady climate. We conclude that environmental noise appears to be crucial to interpreting the past behavior of ice sheets, as well as to predicting their future evolution.

  14. Roads Near Streams

    Data.gov (United States)

    U.S. Environmental Protection Agency — Roads are a source of auto related pollutants (e.g. gasoline, oil and other engine fluids). When roads are near streams, rain can wash these pollutants directly into...

  15. Streaming tearing mode

    Science.gov (United States)

    Shigeta, M.; Sato, T.; Dasgupta, B.

    1985-01-01

    The magnetohydrodynamic stability of streaming tearing mode is investigated numerically. A bulk plasma flow parallel to the antiparallel magnetic field lines and localized in the neutral sheet excites a streaming tearing mode more strongly than the usual tearing mode, particularly for the wavelength of the order of the neutral sheet width (or smaller), which is stable for the usual tearing mode. Interestingly, examination of the eigenfunctions of the velocity perturbation and the magnetic field perturbation indicates that the streaming tearing mode carries more energy in terms of the kinetic energy rather than the magnetic energy. This suggests that the streaming tearing mode instability can be a more feasible mechanism of plasma acceleration than the usual tearing mode instability.

  16. Trout Stream Special Regulations

    Data.gov (United States)

    Minnesota Department of Natural Resources — This layer shows Minnesota trout streams that have a special regulation as described in the 2006 Minnesota Fishing Regulations. Road crossings were determined using...

  17. Scientific stream pollution analysis

    National Research Council Canada - National Science Library

    Nemerow, Nelson Leonard

    1974-01-01

    A comprehensive description of the analysis of water pollution that presents a careful balance of the biological,hydrological, chemical and mathematical concepts involved in the evaluation of stream...

  18. Elucidating Critical Zone Process Interactions with an Integrated Hydrology Model in a Headwaters Research Catchment

    Science.gov (United States)

    Collins, C.; Maxwell, R. M.

    2017-12-01

    Providence Creek (P300) watershed is an alpine headwaters catchment located at the Southern Sierra Critical Zone Observatory (SSCZO). Evidence of groundwater-dependent vegetation and drought-induced tree mortality at P300 along with the effect of subsurface characterization on mountain ecohydrology motivates this study. A hyper resolution integrated hydrology model of this site, along with extensive instrumentation, provides an opportunity to study the effects of lateral groundwater flow on vegetation's tolerance to drought. ParFlow-CLM is a fully integrated surface-subsurface model that is driven with reconstructed meteorology, such as the North American Land Data Assimilation System project phase 2 (NLDAS-2) dataset. However, large-scale data products mute orographic effects on climate at smaller scales. Climate variables often do not behave uniformly in highly heterogeneous mountain regions. Therefore, forcing physically-based integrated hydrologic models—especially of mountain headwaters catchments—with a large-scale data product is a major challenge. Obtaining reliable observations in complex terrain is challenging and while climate data products introduce uncertainties likewise, documented discrepancies between several data products and P300 observations suggest these data products may suffice. To tackle these issues, a suite of simulations was run to parse out (1) the effects of climate data source (data products versus observations) and (2) the effects of climate data spatial variability. One tool for evaluating the effect of climate data on model outputs is the relationship between latent head flux (LH) and evapotranspiration (ET) partitioning with water table depth (WTD). This zone of LH sensitivity to WTD is referred to as the "critical zone." Preliminary results suggest that these critical zone relationships are preserved despite forcing albeit significant shifts in magnitude. These results demonstrate that integrated hydrology models are sensitive

  19. Sediment transport in headwaters of a volcanic catchment—Kamchatka Peninsula case study

    Science.gov (United States)

    Chalov, Sergey R.; Tsyplenkov, Anatolii S.; Pietron, Jan; Chalova, Aleksandra S.; Shkolnyi, Danila I.; Jarsjö, Jerker; Maerker, Michael

    2017-09-01

    Due to specific environmental conditions, headwater catchments located on volcanic slopes and valleys are characterized by distinctive hydrology and sediment transport patterns. However, lack of sufficient monitoring causes that the governing processes and patterns in these areas are rarely well understood. In this study, spatiotemporal water discharge and sediment transport from upstream sources was investigated in one of the numerous headwater catchments located in the lahar valleys of the Kamchatka Peninsula Sukhaya Elizovskaya River near Avachinskii and Koryakskii volcanoes. Three different subcatchments and corresponding channel types (wandering rivers within lahar valleys, mountain rivers within volcanic slopes and rivers within submountain terrains) were identified in the studied area. Our measurements from different periods of observations between years 2012-2014 showed that the studied catchment was characterized by extreme diurnal fluctuation of water discharges and sediment loads that were influenced by snowmelt patterns and high infiltration rates of the easily erodible lahar deposits. The highest recorded sediment loads were up to 9•104 mg/L which was related to an increase of two orders of magnitude within a one day of observations. Additionally, to get a quantitative estimate of the spatial distribution of the eroded material in the volcanic substrates we applied an empirical soil erosion and sediment yield model-modified universal soil loss equation (MUSLE). The modeling results showed that even if the applications of the universal erosion model to different non-agricultural areas (e.g., volcanic catchments) can lead to irrelevant results, the MUSLE model delivered might be acceptable for non-lahar areas of the studied volcanic catchment. Overall the results of our study increase our understanding of the hydrology and associated sediment transport for prediction of risk management within headwater volcanic catchments.

  20. 50 years of change at 14 headwater snowmelt-dominated watersheds in Wyoming

    Science.gov (United States)

    Voutchkova, D. D.; Miller, S. N.

    2017-12-01

    Wyoming is a headwater state contributing to the water resources of four major US basins: Columbia River, Colorado River, Great Basin, and Missouri River. Most of the annual precipitation in this semi-arid state is received at high elevations as snow. Water availability for drinking water supply, reservoir storage, industrial, agricultural, and ecological needs - all depends on the variable and potentially changing annual snowmelt. Thus, characterizing snowmelt and snowmelt-dominated runoff variability and change at high-elevation headwater watersheds in Wyoming is of utmost importance. Next to quantifying variability and changes in total precipitation, snow-water equivalent (SWE), annual runoff and low flows at 14 selected and representative high-elevation watersheds during the previous 50 years, we also explore past watershed disturbances. Wildfires, forest management (e.g. timber harvest), and recent bark beetle outbakes have altered the vegetation and potentially the hydrology of these high-elevation watersheds. We present a synthesis and trend analysis of 49-75 complete water years (wy) of daily streamflow data for 14 high-elevation watersheds, 25-36 complete wy of daily SWE and precipitation data for the closest SNOTEL stations, and spatiotemporal data on burned areas for 20 wy, tree mortality for 18 wy, timber harvest during the 20th century, as well as overview on legacy tie-drive related distrbances. These results are discussed with respect to the differing watershed characteristics in order to present a spectrum of possible hydrologic responses. The importance of our work lies in extending our understanding of snowmelt headwater annual runoff and low-flow dynamics in Wyoming specifically. Such regional synthesis would inform and facilitate water managers and planners both at local state-wide level, but also in the intermountain US West.