Downstream and Lateral Transport of Nymphs of Two Mayfly Species (Ephemeroptera)

1983 ◽  
Vol 40 (11) ◽  
pp. 2025-2029 ◽  
Author(s):  
Jan J. H. Ciborowski
Keyword(s):  
Water Column ◽  
Velocity Gradient ◽  
Current Velocity ◽  
Lateral Transport ◽  
Cross River ◽  
Baetis Tricaudatus ◽  
Settling Behavior ◽  
Mean Current ◽  
Lateral Dispersal

By releasing live and dead nymphs of two mayfly species, Baetis tricaudatus Dodds and Ephemerella inermis Eaton, into the water column of a river and catching them downstream in a series of contiguous nets, I estimated settling and lateral dispersal rates. Live animals settled over shorter distances than dead individuals, and became more widely laterally dispersed for any given distance downstream and mean current velocity. Transport of suspended organisms in a river in which mean current velocity increases with increasing distance from shore may produce a skewed cross-river benthic distribution of animals. The degree of skewness will depend on the current velocity gradient and on suspended animals' settling behavior.

Influence of current velocity, density, and detritus on drift of two mayfly species (Ephemeroptera)

1983 ◽  
Vol 61 (1) ◽  
pp. 119-125 ◽  
Author(s):  
Jan J. H. Ciborowski
Keyword(s):  
Water Column ◽  
Linear Function ◽  
Current Velocity ◽  
Substantial Proportion ◽  
Positive Linear Function ◽  
Laboratory Streams ◽  
Indirect Consequence ◽  
Baetis Tricaudatus ◽  
Mean Current

Drift responses of Baetis tricaudatus Dodds and Ephemerella inermis Eaton larvae to manipulations of benthic density, sterile detritus, and current velocity were monitored in laboratory streams. The proportion of larvae departing from the substrate was independent of benthic density, amount of detritus, and interactions between these two variables. In spring, departure of larvae of both species was a positive linear function of current velocity during daylight hours. In darkness, departure of B. tricaudatus larvae became a negative linear function of current velocity. Nocturnal drift of E. inermis larvae was minimal at a mean current velocity of 25 cm∙s−1 and greater at both higher and lower velocities. None of the factors tested influenced departure of B. tricaudatus larvae in autumn experiments. Dead larvae were eroded from the substrate in much smaller proportions than were their live counterparts. This suggests that appearance in the water column of live animals is the direct or indirect consequence of individuals' behaviour. Departure of animals during daytime is largely passive in nature, whereas a substantial proportion of nocturnal drift probably results from active desertion of the substrate.

scholarly journals Modelling the effect of boundary scavenging on Thorium and Protactinium profiles in the ocean

2009 ◽  
Vol 6 (4) ◽  
pp. 7853-7896 ◽  
Author(s):  
M. Roy-Barman
Keyword(s):  
Arctic Ocean ◽  
Water Column ◽  
Open Ocean ◽  
The Arctic ◽  
Transport Parameters ◽  
Lateral Transport ◽  
Transport Reaction ◽  
The Pacific ◽  
The Arctic Ocean ◽  
Boundary Scavenging

Abstract. The "boundary scavenging" box model is a cornerstone of our understanding of the particle-reactive radionuclide fluxes between the open ocean and the ocean margins. However, it does not describe the radionuclide profiles in the water column. Here, I present the transport-reaction equations for radionuclides transported vertically by reversible scavenging on settling particles and laterally by horizontal currents between the margin and the open ocean. Analytical solutions of these equations are compared with existing data. In the Pacific Ocean, the model produces "almost" linear 230Th profiles (as observed in the data) despite lateral transport. However, omitting lateral transport biased the 230Th based particle flux estimates by as much as 50%. 231Pa profiles are well reproduced in the whole water column of the Pacific Margin and from the surface down to 3000 m in the Pacific subtropical gyre. Enhanced bottom scavenging or inflow of 231Pa-poor equatorial water may account for the model-data discrepancy below 3000 m. The lithogenic 232Th is modelled using the same transport parameters as 230Th but a different source function. The main source of 232Th scavenged in the open Pacific is advection from the ocean margin, whereas a net flux of 230Th produced in the open Pacific is advected and scavenged at the margin, illustrating boundary exchange. In the Arctic Ocean, the model reproduces 230Th measured profiles that the uni-dimensional scavenging model or the scavenging-ventilation model failed to explain. Moreover, if lateral transport is ignored, the 230Th based particle settling speed may by underestimated by a factor 4 at the Arctic Ocean margin. The very low scavenging rate in the open Arctic Ocean combined with the enhanced scavenging at the margin accounts for the lack of high 231Pa/230Th ratio in arctic sediments.

Mean current velocity measurement from a movable base

1994 ◽  
Vol 5 (5) ◽  
pp. 395-399
Author(s):  
N. P. Bulgakov ◽  
V. I. Remchukov ◽  
A. G. Evgushchenko
Keyword(s):  
Current Velocity ◽  
Velocity Measurement ◽  
Mean Current

scholarly journals Snare Performance for Sunken and Submerged Oil Detection and Monitoring

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
M.P. VERFAILLIE ◽  
M.D. GLOEKLER ◽  
N.E. KINNER ◽  
E.A. BALCOM ◽  
C.A. BERNARDY ◽  
...  
Keyword(s):  
Water Column ◽  
Oil Spill ◽  
Current Velocity ◽  
Developed Countries ◽  
Fuel Oil ◽  
Detection Techniques ◽  
Drag Forces ◽  
Plastic Bags ◽  
A Chain ◽  
Sunken Oil

ABSTRACT - 687127 Most oil spill response strategies, tactics, and equipment are designed to address floating oil. Previous research and historic events have shown that spilled oil can suspend (i.e., submerged oil) or sink (i.e., sunken oil) as a function of the oil's density relative to that of the receiving waters. Processes such as wave action or current velocity, sediment entrainment, and oil weathering (e.g., evaporation) may change the buoyancy of floating oils causing them to submerge or sink. Non-floating oil is more difficult and expensive to detect and poses significant challenges for containment and cleanup. Many existing detection techniques for non-floating oils rely on oleophilic sorbents, such as snare, which are weighted depending upon the oil's location in the water column and then towed behind a vessel in designated transects. Currently, there is no quantitative method to relate the amount of oil collected by snare to the amount of oil encountered during towing. In addition, the dynamics and interactions of towed snare and oil remain largely unknown. To address these knowledge gaps, various components of snare performance have been evaluated since 2016 by the Coastal Response Research Center (CRRC) at the University of New Hampshire (UNH). The research has evaluated: (1) the impacts of temperature, salinity, oil type, and tow velocity on adsorption and desorption of oil to snare, (2) snare dynamics and position in the water column as a function of tow velocity, (3) the impacts of material type and potential alternatives to snare (e.g., mosquito and fishing nets, plastic debris) for lesser developed countries (LDCs), and (4) the interaction of snare with sunken and submerged oil. The results determined: (1) adsorption of oil to snare was best for less viscous oils (No. 6 Fuel Oil) and lower water temperatures (5°C) and desorption was greatest at low temperatures (6°C) and low current velocities (< 1 knot), while salinity had no significant effect. (2) Tow depth for snare arrays decreased with increased velocity unless a vane was used. (3) Optimal spacing of snare on a chain is a function of tow and current velocity, and drag forces on the tow chain. (4) Snare alternatives with greatest potential for sunken oil detection in LDCs were nylon mosquito netting and plastic bags. The findings from this research improves understanding of the behavior of snare and how it interacts with sunken and submerged oil and can improve towing techniques used by oil spill responders, leading to more effective detection.

Dissolved silicon and its isotopes in the water column of the Bay of Bengal: Internal cycling versus lateral transport

2015 ◽  
Vol 151 ◽  
pp. 172-191 ◽  
Author(s):  
Satinder Pal Singh ◽  
Sunil Kumar Singh ◽  
Ravi Bhushan ◽  
Vinai Kumar Rai
Keyword(s):  
Water Column ◽  
Bay Of Bengal ◽  
Lateral Transport ◽  
Dissolved Silicon ◽  
Internal Cycling

scholarly journals Modelling the effect of boundary scavenging on Thorium and Protactinium profiles in the ocean

2009 ◽  
Vol 6 (12) ◽  
pp. 3091-3107 ◽  
Author(s):  
M. Roy-Barman
Keyword(s):  
Arctic Ocean ◽  
Water Column ◽  
Open Ocean ◽  
The Arctic ◽  
Transport Parameters ◽  
Lateral Transport ◽  
Transport Reaction ◽  
The Pacific ◽  
The Arctic Ocean ◽  
Boundary Scavenging

Abstract. The "boundary scavenging" box model is a cornerstone of our understanding of the particle-reactive radionuclide fluxes between the open ocean and the ocean margins. However, it does not describe the radionuclide profiles in the water column. Here, I present the transport-reaction equations for radionuclides transported vertically by reversible scavenging on settling particles and laterally by horizontal currents between the margin and the open ocean. Analytical solutions of these equations are compared with existing data. In the Pacific Ocean, the model produces "almost" linear 230Th profiles (as observed in the data) despite lateral transport. However, omitting lateral transport biaises the 230Th based particle flux estimates by as much as 50%. 231Pa profiles are well reproduced in the whole water column of the Pacific Margin and from the surface down to 3000 m in the Pacific subtropical gyre. Enhanced bottom scavenging or inflow of 231Pa-poor equatorial water may account for the model-data discrepancy below 3000 m. The lithogenic 232Th is modelled using the same transport parameters as 230Th but a different source function. The main source of the 232Th scavenged in the open Pacific is advection from the ocean margin, whereas a net flux of 230Th produced in the open Pacific is advected and scavenged at the margin, illustrating boundary exchange. In the Arctic Ocean, the model reproduces 230Th measured profiles that the uni-dimensional scavenging model or the scavenging-ventilation model failed to explain. Moreover, if lateral transport is ignored, the 230Th based particle settling speed may by underestimated by a factor 4 at the Arctic Ocean margin. The very low scavenging rate in the open Arctic Ocean combined with the enhanced scavenging at the margin accounts for the lack of high 231Pa/230Th ratio in arctic sediments.

MOVEMENT AND EROSION OF ALBERTA BITUMEN ALONG THE BOTTTOM AS A FUNCTION OF TEMPERATURE, WATER VELOCITY AND SALINITY

2017 ◽  
Vol 2017 (1) ◽  
pp. 2306-2326
Author(s):  
M.D. GLOEKLER ◽  
T.P. BALLESTERO ◽  
E.V. DAVE ◽  
I.P. GAUDREAU ◽  
C.B.R. WATKINS ◽  
...  
Keyword(s):  
Shear Stress ◽  
Water Column ◽  
Current Velocity ◽  
Critical Shear Stress ◽  
Heavy Oils ◽  
Annular Flume ◽  
Length Width ◽  
Higher Temperature ◽  
Trajectory Models ◽  
Temperature Water

Abstract While many trajectory models exist to predict the movement of oil floating in or on water, few are designed to address heavy oil on the bottom of water bodies. In addition, remobilization (erosion) of the material into the water column is also difficult to predict. While properties such as adhesion, viscosity and density of oil may be readily measured, the critical shear stress (CSS) and the effect of (current) velocity, salinity, and temperature are virtually unknown for most heavy oils. The Coastal Response Research Center (CRRC) has a 4,000 L annular flume, with a water depth of 0.43 m. An inner rectangular flume (1.2 m length, 0.2m width, 0.9 m height), placed inside the annular flume, was preceded by two flow straighteners to reduced turbulence and produce a uniform, one dimensional flow field. The current is generated by an electric thrust motor and measured in 3D by a Nortek AS (Norway) Vectrino II Profiling Velocimeter. A 20g circle of Alberta bitumen (API ~ 10°) was placed on a laminated grid (1cm2 square pattern) at the bottom of the straight flume. A total of 2.3m3 of water was then gradually added to the flume. The electric motor was started and the profiler began collecting data. Two cameras, placed along the side and above the oil, collected video of the erosions and length/width changes of the oil. Conditions were held steady for one hour once the desired current velocity was achieved. Temperatures, current velocity (X, Y, Z), and digital videographic data were collected during each run. Erosions and percent lengthening of the oil was monitored as a function of water temperature, salinity and velocity. The turbulent kinetic energy (TKE) method was used to calculate the bed shear stress (BSS). In addition to the expected impact of higher temperature on the movement along the bed and erosion into the water column, the viscoelastic and shear-thinning properties of the bitumen played a role in its behavior (lowering of viscosity at higher BSS slowing erosions and movement) and must be considered when predicting its behavior during a spill.

Optimum Swimming Speeds in Fish: The Problem of Currents

1980 ◽  
Vol 37 (7) ◽  
pp. 1086-1092 ◽  
Author(s):  
Clifford L. Trump ◽  
William C. Leggett
Keyword(s):  
Energy Expenditure ◽  
Swimming Speed ◽  
Current Velocity ◽  
Migration Behavior ◽  
Fish Swimming ◽  
Retrograde Motion ◽  
The Mean ◽  
The Relationship ◽  
Mean Current ◽  
A Current

A model is presented describing the energetic consequences of various behavioral responses to currents. To minimize the energy cost of migration, when confronted with currents, fish must optimize both the mean swimming speed and the degree to which swimming speed is altered in response to changes in current velocity. The optimum swimming speed in a current is U0 + 1/b where U0 = mean current speed and b is a constant in the equation E(t) = a ebW(t) describing the relationship between specific energy expenditure per unit time E(t) and swimming speed W(t). In a variable current, such as might occur in estuaries and coastal areas, energy expenditure is minimized when these variations are ignored and a constant speed through the water is maintained. This is true even in conditions where occasional retrograde motion over the bottom may occur. The added energy costs of swimming at mean speeds ≠ U0 + 1/b or of varying swimming speeds in response to changes in current velocity are rigorously defined. Predictions of the model are in general agreement with empirical data on fish swimming behavior.Key words: swimming speeds, currents, fish, theoretical ecology, mathematical models, energetics, migration, behavior

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