The role of the geophysical template and environmental regimes in controlling stream-living trout populations

2015 ◽  
Vol 72 (6) ◽  
pp. 893-901 ◽  
Author(s):  
Brooke E. Penaluna ◽  
Steve F. Railsback ◽  
Jason B. Dunham ◽  
Sherri Johnson ◽  
Robert E. Bilby ◽  
...  
Keyword(s):  
Fish Habitat ◽  
Spatiotemporal Variability ◽  
Sensitivity Analyses ◽  
Low Flow ◽  
Aquatic Biota ◽  
Relative Role ◽  
Oncorhynchus Clarkii ◽  
Environmental Regimes ◽  
Multiple Processes

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.

scholarly journals Variability of low flow magnitudes in the Upper Colorado River Basin: identifying trends and relative role of large-scale climate dynamics

2014 ◽  
Vol 11 (7) ◽  
pp. 8779-8802 ◽  
Author(s):  
M. Pournasiri Poshtiri ◽  
I. Pal
Keyword(s):  
River Basin ◽  
Large Scale ◽  
River Flow ◽  
Colorado River ◽  
Colorado River Basin ◽  
Low Flow ◽  
Anthropogenic Factors ◽  
Relative Role ◽  
Water Abstraction

Abstract. Low flow magnitude in a head water basin is important for planners because minimum available amount of water in a given time period often leads to concerns regarding serious repercussions, in both up and downstream regions. This is a common scenario in arid region like Colorado River basin located in the southwestern US. Low flow variability in Colorado River is due to complex interactions between several natural and anthropogenic factors; but we aim to identify the relative role of climate on varying low flow magnitudes at different spatial locations. The research questions we aim to answer are: Is there a systematic variability in water availability during the driest time of a year or season? How does that vary across locations and is there a link between large-scale climate and low flow variations? Towards that aim we select 17 stream gauge locations, which are identified as "undisturbed" meaning that these stations represent near-natural river flow regimes in the headwater region of Colorado River, which provides a useful resource for assessment of climate and hydrology associations without the confounding factor of major direct (e.g. water abstraction) or indirect (e.g. land-use change) human modification of flows. A detailed diagnostic analysis gives us fair understanding on the variability of low flow magnitude that is explained by climate. We also present spatial heterogeneity of hydro-climatological linkages that is important for suitable adaptive management measures.

scholarly journals Regional pulmonary perfusion patterns in humans are not significantly altered by inspiratory hypercapnia

2019 ◽  
Vol 127 (2) ◽  
pp. 365-375
Author(s):  
Amran K. Asadi ◽  
Rui Carlos Sá ◽  
Tatsuya J. Arai ◽  
Rebecca J. Theilmann ◽  
Susan R. Hopkins ◽  
...  
Keyword(s):  
Blood Flow ◽  
Regional Perfusion ◽  
Spatiotemporal Variability ◽  
Pulmonary Perfusion ◽  
Relative Role ◽  
Alveolar Hypoxia ◽  
Dynamic Measures ◽  
End Tidal ◽  
The Right

Pulmonary vascular tone is known to be sensitive to both local alveolar Po2 and Pco2. Although the effects of hypoxia are well studied, the hypercapnic response is relatively less understood. We assessed changes in regional pulmonary blood flow in humans in response to hypercapnia using previously developed MRI techniques. Dynamic measures of blood flow were made in a single slice of the right lung of seven healthy volunteers following a block-stimulus paradigm (baseline, challenge, recovery), with CO2 added to inspired gas during the challenge block to effect a 7-Torr increase in end-tidal CO2. Effects of hypercapnia on blood flow were evaluated based on changes in spatiotemporal variability (fluctuation dispersion, FD) and in regional perfusion patterns in comparison to hypoxic effects previously studied. Hypercapnia increased FD 2.5% from baseline (relative to control), which was not statistically significant ( P = 0.07). Regional perfusion patterns were not significantly changed as a result of increased [Formula: see text] ( P = 0.90). Reanalysis of previously collected data using a similar protocol but with the physiological challenge replaced by decreased [Formula: see text] ([Formula: see text] = 0.125) showed marked flow redistribution ( P = 0.01) with the suggestion of a gravitational pattern, demonstrating hypoxia has the ability to affect regional change with a global stimulus. Taken together, these data indicate that hypercapnia of this magnitude does not lead to appreciable changes in the distribution of pulmonary perfusion, and that this may represent an interesting distinction between the hypoxic and hypercapnic regulatory response. NEW & NOTEWORTHY Although it is well known that the pulmonary circulation responds to local alveolar hypoxia, and that this mechanism may facilitate ventilation-perfusion matching, the relative role of CO2 is not well appreciated. This study demonstrates that an inspiratory hypercapnic stimulus is significantly less effective at inducing changes in pulmonary perfusion patterns than inspiratory hypoxia, suggesting that in these circumstances hypercapnia is not sufficient to induce substantial integrated feedback control of ventilation-perfusion mismatch across the lung.

scholarly journals Forensic Investigation of Four Monitored Green Infrastructure Inlets

Water ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 1787
Author(s):  
Leena J. Shevade ◽  
Franco A. Montalto
Keyword(s):  
Measurement Uncertainty ◽  
Green Infrastructure ◽  
Stormwater Management ◽  
Catchment Area ◽  
Low Flow ◽  
Inflow Rate ◽  
Forensic Investigation ◽  
Flow Conditions ◽  
The Mean

Green infrastructure (GI) is viewed as a sustainable approach to stormwater management that is being rapidly implemented, outpacing the ability of researchers to compare the effectiveness of alternate design configurations. This paper investigated inflow data collected at four GI inlets. The performance of these four GI inlets, all of which were engineered with the same inlet lengths and shapes, was evaluated through field monitoring. A forensic interpretation of the observed inlet performance was conducted using conclusions regarding the role of inlet clogging and inflow rate as described in the previously published work. The mean inlet efficiency (meanPE), which represents the percentage of tributary area runoff that enters the inlet was 65% for the Nashville inlet, while at Happyland the NW inlet averaged 30%, the SW inlet 25%, and the SE inlet 10%, considering all recorded events during the monitoring periods. The analysis suggests that inlet clogging was the main reason for lower inlet efficiency at the SW and NW inlets, while for the SE inlet, performance was compromised by a reverse cross slope of the street. Spatial variability of rainfall, measurement uncertainty, uncertain tributary catchment area, and inlet depression characteristics are also correlated with inlet PE. The research suggests that placement of monitoring sensors should consider low flow conditions and a strategy to measure them. Additional research on the role of various maintenance protocols in inlet hydraulics is recommended.

scholarly journals The Role of Frost Processes in the Retreat of River Banks

Water ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 1812
Author(s):  
Karol Augustowski ◽  
Józef Kukulak
Keyword(s):  
Relative Role ◽  
Freezing And Thawing ◽  
Fine Grained ◽  
Fluvial Processes ◽  
Precise Calculation ◽  
Erosion Pins ◽  
Summer Half ◽  
Lateral Erosion ◽  
Summer Flood

The rate of bank retreat was measured using erosion pins on the alluvial banks of the rivers in the Podhale region (the boundary zone between Central and Outer Carpathians) during the hydrological year 2013/2014. During the winter half-year (November–April), the bank retreat was mainly caused by processes related to the freezing and thawing of the ground (swelling, creep, downfall). During the summer half-year (May–October), fluvial processes and mass movements such as lateral erosion, washing out, and sliding predominated. The share of fluvial processes in the total annual amount of bank retreat (71 cm on average) was 4 times greater than that of the frost phenomena. Erosion on bank surfaces by frost phenomena during the cold half-year was greatest (up to 38 cm) on the upper parts of banks composed of fine-grained alluvium, while fluvial erosion during the summer half-year (exceeding 80 cm) mostly affected the lower parts of the banks, composed of gravel. The precise calculation of the relative role of frost phenomena in the annual balance of bank erosion was precluded at some stations by the loss of erosion pins in the summer flood.

Grain Boundary Segregation in Titanium Dioxide: Evaluation of Relative Driving Forces for Segregation

2002 ◽  
Vol 751 ◽  
Author(s):  
Qinglei Wang ◽  
Guoda D. Lian ◽  
Elizabeth C. Dickey
Keyword(s):  
Titanium Dioxide ◽  
Driving Forces ◽  
Boundary Segregation ◽  
Solute Segregation ◽  
Dielectric Behavior ◽  
Relative Role ◽  
Transmission Electron ◽  
Fundamental Phenomenon ◽  
Versus Strain

ABSTRACTSolute segregation to grain boundaries is a fundamental phenomenon in polycrystalline metal-oxide electroceramics that has enormous implications for the macroscopic dielectric behavior of the materials. This paper presents a systematic study of solute segregation in a model dielectric, titanium dioxide. We investigate the relative role of the electrostatic versus strain energy driving forces for segregation by studying yttrium-doped specimens. Through analytical transmission electron microscopy studies, we quantitatively determine the segregation behavior of the material. The measured Gibbsian interfacial excesses are compared to thermodynamic predictions.

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