An Evaluation by Field Experiments of the McLay Model of Stream Drift

1985 ◽  
Vol 42 (5) ◽  
pp. 909-918 ◽  
Author(s):  
P. A. Larkin ◽  
D. W. McKone
Keyword(s):  
Linear Function ◽  
Field Experiments ◽  
Drift Rate ◽  
Stream Velocity ◽  
Upstream Migration ◽  
Spatial Differences ◽  
Natural Drift ◽  
Stream Drift

The model of McLay (J. Fish. Res. Board Can. 27: 359–370) for describing the drift of stream organisms was tested in a variety of field experiments in which organisms were disturbed from the substrate and/or the natural drift was blocked. In each situation, appropriate corrections may be made for the catch of drift organisms by the sampling nets. Disturbed animals drifted at a rate much less than stream velocity. The logarithm of the distance travelled was a linear function of the logarithm of mean stream velocity and conformed to the McLay model. Similarly, the model adequately described experiments in which two disturbances were done simultaneously, when drift was blocked for a 2-h period, and when there was both disturbance and blockage. A more comprehensive version of the model was only partially successful in describing the drift at various distances downstream of a blockage sustained for 4 d, probably because of upstream migration of organisms through the substrate, spatial differences in the densities of animals in the substrate, or a reduction in drift rate at lower density in the substrate.

scholarly journals Upstream guppies (Poecilia reticulata, Peters, 1859) go against the flow

2012 ◽  
Vol 12 (3) ◽  
pp. 68-72 ◽  
Author(s):  
Ryan Simon Mohammed ◽  
Cock van Oosterhout ◽  
Bettina Schelkle ◽  
Joanne Cable ◽  
Mark McMullan
Keyword(s):  
Natural Selection ◽  
Poecilia Reticulata ◽  
Downstream Migration ◽  
Upstream Migration ◽  
Station Keeping ◽  
Significant Difference ◽  
Spatial Differences ◽  
Riverine Habitat ◽  
Ecology And Environment ◽  
Flooding Events

Guppies (Poecilia reticulata Peters 1859) in lakes and from captive-bred populations are predicted to show little rheotaxis compared to conspecifics in a stream environment that are regularly exposed to flash floods associated with involuntary downstream migration. Here we test this hypothesis using an artificial stream, examining guppies of two wild riverine populations, one lake population, and one ornamental strain. Guppies from the most upstream riverine habitat show the most pronounced rheotaxis and are less likely to be swept downstream during flooding events. However, there is no significant difference between guppies from the lowland riverine habitat, the Pitch Lake and ornamental strain. We propose that station-keeping behaviours are most strongly selected in the upstream population because large spatial differences exist in ecology and environment between up- and downstream habitats. Given that these sites are separated by barrier waterfalls that prevent compensatory upstream migration, natural selection operates particularly strong against upstream guppies that have been displaced downstream during flooding events.

scholarly journals Determination of hydrological roughness by means of close range remote sensing

SOIL ◽  
2015 ◽  
Vol 1 (2) ◽  
pp. 613-620 ◽  
Author(s):  
A. Kaiser ◽  
F. Neugirg ◽  
F. Haas ◽  
J. Schmidt ◽  
M. Becht ◽  
...  
Keyword(s):  
Field Experiments ◽  
Soil Surface ◽  
Field Work ◽  
Stream Velocity ◽  
Sigmoid Function ◽  
Statistical Parameters ◽  
Hydraulic Roughness ◽  
Central Brazil ◽  
Physically Based ◽  
Close Range

Abstract. The objective of the presented work was to develop a method to acquire Manning's n by creating very high-resolution surface models with structure-from-motion methods. As hydraulic roughness is an essential parameter for physically based erosion models, a practical measuring technique is valuable during field work. Data acquisition took place during several field experiments in the Lainbach valley, southern Germany, and on agricultural sites in Saxony, eastern Germany, and in central Brazil. Rill and interrill conditions were simulated by flow experiments. In order to validate our findings stream velocity was measured with colour tracers. Grain sizes were derived by measuring distances from a best fit line to the reconstructed soil surface. Several diameters from D50 to D90 were tested with D90 showing best correlation between tracer experiments and photogrammetrically acquired data. Several roughness parameters were tested (standard deviation, random roughness, Garbrecht's n and D90). Best agreement in between the grain size and the hydraulic roughness was achieved with a non-linear sigmoid function and D90 rather than with the Garbrecht equation or statistical parameters.

scholarly journals Analysis of Biostimulated Microbial Communities from Two Field Experiments Reveals Temporal and Spatial Differences in Proteome Profiles

2010 ◽  
Vol 44 (23) ◽  
pp. 8897-8903 ◽  
Author(s):  
Stephen J. Callister ◽  
Michael J. Wilkins ◽  
Carrie D. Nicora ◽  
Kenneth H. Williams ◽  
Jillian F. Banfield ◽  
...  
Keyword(s):  
Microbial Communities ◽  
Field Experiments ◽  
Spatial Differences ◽  
Temporal And Spatial

scholarly journals Determination of hydrological roughness by means of close range remote sensing

2015 ◽  
Vol 2 (1) ◽  
pp. 401-425
Author(s):  
A. Kaiser ◽  
F. Neugirg ◽  
F. Haas ◽  
J. Schmidt ◽  
M. Becht ◽  
...  
Keyword(s):  
Field Experiments ◽  
Soil Surface ◽  
Field Work ◽  
Stream Velocity ◽  
Sigmoid Function ◽  
Statistical Parameters ◽  
Hydraulic Roughness ◽  
Central Brazil ◽  
Physically Based ◽  
Close Range

Abstract. The objective of the presented work was to develop a method to acquire Manning's n by creating very high resolution surface models with Structure from Motion-methods. As hydraulic roughness is an essential parameter for physically based erosion models, a practical measuring technique is valuable during field work. Data acquisition took place during several field experiments in the Lainbach valley, southern Germany and on agricultural sites in Saxony, eastern Germany and in central Brazil. Rill and interrill conditions were simulated by flow experiments. In order to validate our findings stream velocity was measured with colour tracers. Grain sizes were derived by measuring distances from a best fit line to the reconstructed soil surface. Several diameters from D50 to D90 were tested with D90 showing best correlation between tracer experiments and photogrammetrically acquired data. Several roughness parameters were tested (standard deviation, random roughness, Garbrechts n and D90). Best agreement in between the grain size and the hydraulic roughness was achieved with a non-linear sigmoid function and D90 rather than with the Garbrecht equation or statistical parameters.

Drift Responses of Benthic Invertebrates to Experimental Streamflow Variation in a Hydrologically Stable Stream

1991 ◽  
Vol 48 (10) ◽  
pp. 1926-1936 ◽  
Author(s):  
N. LeRoy Poff ◽  
J. V. Ward
Keyword(s):  
Benthic Invertebrates ◽  
Field Experiments ◽  
Colorado River ◽  
Drift Rate ◽  
Chironomidae Larvae ◽  
Drift Density ◽  
Reduced Flow

Field experiments were conducted in the regulated upper Colorado River to assess drift responses of lotic macroinvertebrates to streamflow manipulations. In each of three seasons, drift was collected in one control and two experimental riffles. On the first day, no flow manipulations occurred. Six hours before sunset on the second day, streamflow was simultaneously reduced and elevated in two experimental riffles with instream diversion structures. Following flow elevation, both mean daily drift density and drift rate generally increased for 13 taxa across all seasons. Flow reductions generally induced elevated drift densities for most taxa, but drift rates declined for some taxa. Patterns of diel drift periodicity were less frequently modified by flow manipulations. Taxa with typical nocturnal peaks in drift activity (Baetis spp., Epeorus longimanus, Triznaka signata) generally maintained this pattern despite some increases in diurnal drift. For a few taxa, modification of diel drift patterns occurred, either as nocturnal decreases following reduced flow (Paraleptophlebia heteronea, Ephemerella infrequens) or as diurnal drift increases in response to either elevated flow (Lepidostoma ormea, Chironomidae larvae) or reduced flow (Simuliidae). With some exceptions, observed drift responses could be used to suggest active versus passive processes of drift entry.

Electron Microscopy of the Shape of Small Metal Particles

1977 ◽  
Vol 35 ◽  
pp. 300-301
Author(s):  
M. Jose Yacaman
Keyword(s):  
Electron Microscopy ◽  
Metal Particle ◽  
Field Experiments ◽  
Size Range ◽  
Dark Field ◽  
Metal Particles ◽  
Bragg Condition ◽  
Crystal Particle ◽  
Small Metal Particle ◽  
Small Metal Particles

In the Study of small metal particles the shape is a very Important parameter. Using electron microscopy Ino and Owaga(l) have studied the shape of twinned particles of gold. In that work electron diffraction and contrast (dark field) experiments were used to produce models of a crystal particle. In this work we report a method which can give direct information about the shape of an small metal particle in the amstrong- size range with high resolution. The diffraction pattern of a sample containing small metal particles contains in general several systematic and non- systematic reflections and a two-beam condition can not be used in practice. However a N-beam condition produces a reduced extinction distance. On the other hand if a beam is out of the bragg condition the effective extinction distance is even more reduced.

Successful field experiments: Getting in, getting the data, getting published

2010 ◽  
Author(s):  
Susan M. Kochanowski ◽  
Charles F. Seifert ◽  
Gary A. Yukl ◽  
Dov Eden ◽  
Gary P. Latham
Keyword(s):  
Field Experiments

Optimizing genotype-environment-management interactions to ensure silage maize production in the Chinese Maize Belt

2020 ◽  
Vol 80 (2) ◽  
pp. 133-146
Author(s):  
L Zhang ◽  
Z Zhang ◽  
J Cao ◽  
Y Luo ◽  
Z Li
Keyword(s):  
Field Experiments ◽  
Weather Conditions ◽  
Growth Cycle ◽  
High Energy ◽  
Risk Level ◽  
Energy Yield ◽  
Maize Production ◽  
Early Date ◽  
Environment Management ◽  
Silage Maize

Grain maize production exceeds the demand for grain maize in China. Methods for harvesting good-quality silage maize urgently need a theoretical basis and reference data in order to ensure its benefits to farmers. However, research on silage maize is limited, and very few studies have focused on its energetic value and quality. Here, we calibrated the CERES-Maize model for 24 cultivars with 93 field experiments and then performed a long-term (1980-2017) simulation to optimize genotype-environment-management (G-E-M) interactions in the 4 main agroecological zones across China. We found that CERES-Maize could reproduce the growth and development of maize well under various management and weather conditions with a phenology bias of <5 d and biomass relative root mean square error values of <5%. The simulated results showed that sowing long-growth-cycle cultivars approximately 10 d in advance could yield good-quality silage. The optimal sowing dates (from late May to July) and harvest dates (from early October to mid-November) gradually became later from north to south. A high-energy yield was expected when sowing at an early date and/or with late-maturing cultivars. We found that Northeast China and the North China Plain were potential silage maize growing areas, although these areas experienced a medium or even high frost risk. Southwestern maize experienced a low risk level, but the low soil fertility limited the attainable yield. The results of this paper provide information for designing an optimal G×E×M strategy to ensure silage maize production in the Chinese Maize Belt.

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