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Nicholas Williamson, Tsuyoshi Kobayashi, David Outhet, Lee C Bowling
Cyanobacterial survival following their release in water from major headwaters reservoirs was compared in five New South Wales rivers. Under low flow conditions, cyanobacterial presence disappeared rapidly with distance downstream in the Cudgegong and Hunter Rivers, whereas the other three rivers were contaminated for at least 300 km. Cyanobacterial survival is likely to be impacted by the geomorphology of each river, especially the extent of gravel riffle reaches (cells striking rocks can destroy them) and by the different turbulent flow conditions it produces within each...
May 2018: Harmful Algae
Danielle R Cook, S Mažeika P Sullivan
Dam removal is an increasingly common river restoration option, yet some of the mechanisms leading to ecological changes remain unquantified. We assessed relationships between riffle structure and benthic macroinvertebrate and fish assemblages 2 years after a lowhead dam removal in Ohio, USA. Hydrogeomorphic, water-chemistry, and biotic surveys were conducted at seven study riffles at six time intervals from spring 2014 through summer 2015. The density and diversity of macroinvertebrates and fish were significantly different over time, largely as a function of season (lowest densities in early spring, greatest in summer)...
May 10, 2018: Environmental Monitoring and Assessment
Sean M Naman, Jordan S Rosenfeld, Peter M Kiffney, John S Richardson
1.Increasing habitat availability (i.e. habitat suitable for occupancy) is often assumed to elevate the abundance or production of mobile consumers; however, this relationship is often nonlinear (threshold or unimodal). Identifying the mechanisms underlying these nonlinearities is essential for predicting the ecological impacts of habitat change, yet the functional forms and ultimate causation of consumer-habitat relationships are often poorly understood. 2.Nonlinear effects of habitat on animal abundance may manifest through physical constraints on foraging that restrict consumers from accessing their resources...
May 8, 2018: Journal of Animal Ecology
Heikki Mykrä, Romain Sarremejane, Tiina Laamanen, Satu Maaria Karjalainen, Annamari Markkola, Sirkku Lehtinen, Kaisa Lehosmaa, Timo Muotka
We examined how short-term (19 days) nutrient enrichment influences stream fungal and diatom communities, and rates of leaf decomposition and algal biomass accrual. We conducted a field experiment using slow-releasing nutrient pellets to increase nitrate (NO3 -N) and phosphate (PO4 -P) concentrations in a riffle section of six naturally acidic (naturally low pH due to catchment geology) and six circumneutral streams. Nutrient enrichment increased microbial decomposition rate on average by 14%, but the effect was significant only in naturally acidic streams...
April 16, 2018: Ambio
Scott J Knoer, Allison R Riffle
No abstract text is available yet for this article.
April 1, 2018: American Journal of Health-system Pharmacy: AJHP
Mark Dunscombe, Anne Robertson, Ignacio Peralta-Maraver, Peter Shaw
There is little understanding of the variability in the structure and function of metazoan hyporheic communities across streams draining geologies that weather to produce different pore sizes and, by extension, different hydrological conditions. In this study we selected two catchments in each of three geologies that had differing values of hydraulic conductivity and porosity, and sampled four riffles in each catchment at high and low water levels and at two depths. We found clear differences in the physical template of streams draining different geologies and in the composition and abundance of communities inhabiting the hyporheic zones of streams draining chalk/sandstone and limestone geologies...
July 15, 2018: Science of the Total Environment
Kelly S Johnson, Ed Rankin, Jen Bowman, Jessica Deeds, Natalie Kruse
Mayflies (Order Ephemeroptera) require high quality water and habitat in streams to thrive, so their appearance after restoration is an indicator of ecological recovery. To better understand the importance of restoring in-stream habitat versus water chemistry for macroinvertebrate communities, we developed taxon-specific models of occurrence for five mayfly genera (Caenis, Isonychia, Stenonema, Stenacron, and Baetis) inhabiting streams in the Appalachian Mountains, USA. Presence/absence records from past decades were used to develop single and multiple logistic predictive models based on catchment characteristics (drainage area, gradient), in-stream habitat variables (e...
March 7, 2018: Environmental Monitoring and Assessment
Michael P Venarsky, David M Walters, Robert O Hall, Bridget Livers, Ellen Wohl
In the Colorado Front Range (USA), disturbance history dictates stream planform. Undisturbed, old-growth streams have multiple channels and large amounts of wood and depositional habitat. Disturbed streams (wildfires and logging < 200 years ago) are single-channeled with mostly erosional habitat. We tested how these opposing stream states influenced organic matter, benthic macroinvertebrate secondary production, emerging aquatic insect flux, and riparian spider biomass. Organic matter and macroinvertebrate production did not differ among sites per unit area (m-2 ), but values were 2 ×-21 × higher in undisturbed reaches per unit of stream valley (m-1 valley) because total stream area was higher in undisturbed reaches...
May 2018: Oecologia
Luke A Helgeson, Alex Zelter, Michael Riffle, Michael J MacCoss, Charles L Asbury, Trisha N Davis
Accurate segregation of chromosomes relies on the force-bearing capabilities of the kinetochore to robustly attach chromosomes to dynamic microtubule tips. The human Ska complex and Ndc80 complex are outer-kinetochore components that bind microtubules and are required to fully stabilize kinetochore-microtubule attachments in vivo. While purified Ska complex tracks with disassembling microtubule tips, it remains unclear whether the Ska complex-microtubule interaction is sufficiently strong to make a significant contribution to kinetochore-microtubule coupling...
March 13, 2018: Proceedings of the National Academy of Sciences of the United States of America
Peng Huang, Ting Fong May Chui
The hyporheic zone is the saturated interstitial space surrounding a stream. Water actively moves into, through, and out of the hyporheic zone, resulting in hyporheic exchange (HE), which is crucial to the physicochemical and biological processes in these systems. The HE in pool-riffle sequences is one of the most common forms of HE and has received a vast amount of attention. This study aimed to derive empirical equations to predict the scale, median residence time (RT), and flux of HE in a single pool-riffle sequence by considering stream discharge, bedform geometry, streambed hydraulic conductivity, and groundwater flow...
February 1, 2018: Ground Water
Moncie V Wright, Cole W Matson, Leanne F Baker, Benjamin T Castellon, Preston S Watkins, Ryan S King
A 5-week mesocosm experiment was conducted to investigate the toxicity of titanium dioxide nanoparticles (TiO2 NPs) to periphytic algae in an environmentally-realistic scenario. We used outdoor experimental streams to simulate the characteristics of central Texas streams receiving large discharges of wastewater treatment plant effluent during prolonged periods of drought. The streams were continually dosed and maintained at two concentrations. The first represents an environmentally relevant concentration of 0...
June 1, 2018: Science of the Total Environment
Michael Riffle, Damon H May, Emma Timmins-Schiffman, Molly P Mikan, Daniel Jaschob, William Stafford Noble, Brook L Nunn
Metaproteomics is the characterization of all proteins being expressed by a community of organisms in a complex biological sample at a single point in time. Applications of metaproteomics range from the comparative analysis of environmental samples (such as ocean water and soil) to microbiome data from multicellular organisms (such as the human gut). Metaproteomics research is often focused on the quantitative functional makeup of the metaproteome and which organisms are making those proteins. That is: What are the functions of the currently expressed proteins? How much of the metaproteome is associated with those functions? And, which microorganisms are expressing the proteins that perform those functions? However, traditional protein-centric functional analysis is greatly complicated by the large size, redundancy, and lack of biological annotations for the protein sequences in the database used to search the data...
December 27, 2017: Proteomes
Sean M Hitchman, Martha E Mather, Joseph M Smith, Jane S Fencl
Conserving native biodiversity depends on restoring functional habitats in the face of human-induced disturbances. Low-head dams are a ubiquitous human impact that degrades aquatic ecosystems worldwide. To improve our understanding of how low-head dams impact habitat and associated biodiversity, our research examined complex interactions among three spheres of the total environment. i.e., how low-head dams (anthroposphere) affect aquatic habitat (hydrosphere), and native biodiversity (biosphere) in streams and rivers...
April 1, 2018: Science of the Total Environment
Elizabeth M Riffle
No abstract text is available yet for this article.
November 2017: Nursing Management
Paul C Kusnierz, Christopher M Holbrook
Bed stability is an important stream habitat attribute because it affects geomorphology and biotic communities. Natural resource managers desire indices of bed stability that can be used under a wide range of geomorphic conditions, are biologically meaningful, and are easily incorporated into sampling protocols. To eliminate potential bias due to presence of instream wood and increase precision of stability values, we modified a stream bed instability index (ISI) to include measurements of bankfull depth (dbf ) and median particle diameter (D50 ) only in riffles and increased the pebble count to decrease variability (i...
October 16, 2017: Environmental Monitoring and Assessment
Mónica Rivas Casado, Rocío Ballesteros González, José Fernando Ortega, Paul Leinster, Ros Wright
The multiple protocols that have been developed to characterize river hydromorphology, partly in response to legislative drivers such as the European Union Water Framework Directive (EU WFD), make the comparison of results obtained in different countries challenging. Recent studies have analyzed the comparability of existing methods, with remote sensing based approaches being proposed as a potential means of harmonizing hydromorphological characterization protocols. However, the resolution achieved by remote sensing products may not be sufficient to assess some of the key hydromorphological features that are required to allow an accurate characterization...
September 26, 2017: Sensors
Roy E Barnewall, Carol G Riffle, Randy L Jones, David J Guistino, Richard M Chou, Mike S Anderson, Michelle L Vassar, Carrie A Howland
Ricin toxin may be used as a biological warfare agent and no medical countermeasures are currently available. Here, a well-characterized lot of ricin was aerosolized to determine the delivered dose for future pre-clinical efficacy studies.  Mouse intraperitoneal (IP) median lethal dose (LD50 ) bioassay measured potency at 5.62 and 7.35 μg/kg on Days 0 and 365, respectively. Additional analyses included total protein, sodium dodecyl sulfate polyacrylamide gel electrophoresis, Western blotting, and rabbit reticulocyte lysate activity assay...
December 2017: Journal of Biochemical and Molecular Toxicology
Kristen M Harrigan, Paul A Moore
In flowing systems, fluctuations in the frequency, magnitude, and duration of exposure occurs due to turbulence and geomorphology, causing spatial and temporal variations in chemical exposure at the scale of the organism. Spatial models representing toxicant distribution at the appropriate scales of stream organisms are noticeably missing from the literature. To characterize the fine scale distribution of pollutants in freshwater streams at the scale of a benthic organism, nine artificial stream habitats were created (riffle, pool, run, bend, woody debris) with either sand or gravel substrate...
April 2018: Archives of Environmental Contamination and Toxicology
E M Brambilla, A M C Ruocco, M G Nogueira
The knickzones are defined as locally steep riverbed segments, such as a convex reach in a concave-up longitudinal profile. They are worldwide distributed and geologically well studied, but despite their distinctiveness as a particular kind of macrohabitat there is a notorious lack of ecological knowledge. In this context, this research proposal aims to provide a physical description, in terms of kind of habitats, and a limnological characterization of a basaltic knickzone. Information is based on a case study carried out in the Sapucaí-Mirim River, Southeast Brazil...
July 27, 2017: Brazilian Journal of Biology, Revista Brasleira de Biologia
Stephen Riffle, Rashmi S Hegde
Under hypoxic conditions, tumor cells undergo a series of adaptations that promote evolution of a more aggressive tumor phenotype including the activation of DNA damage repair proteins, altered metabolism, and decreased proliferation. Together these changes mitigate the negative impact of oxygen deprivation and allow preservation of genomic integrity and proliferative capacity, thus contributing to tumor growth and metastasis. As a result the presence of a hypoxic microenvironment is considered a negative clinical feature of many solid tumors...
August 3, 2017: Journal of Experimental & Clinical Cancer Research: CR
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