Flow Fields Inside Stocked Fish Cages and the Near Environment

2011 ◽  
Author(s):  
Lars C. Gansel ◽  
Siri Rackebrandt ◽  
Frode Oppedal ◽  
Thomas A. McClimans
Keyword(s):  
Surface Water ◽  
Atlantic Salmon ◽  
Laboratory Tests ◽  
Numerical Models ◽  
Field Measurements ◽  
Flow Patterns ◽  
Fish Swimming ◽  
Swimming Depth ◽  
Starting Point ◽  
Fish Cages

This study explores the average flow field inside and around stocked Atlantic salmon (Salmo salar L.) fish cages. Laboratory tests and field measurements were conducted to study the effects of biofouling and especially fish behaviour on the flow patterns around and through fish cages. Currents were measured around an empty and a stocked fish cage in a fjord to verify the results obtained from laboratory tests without fish and to study the effects of fish swimming in the cage. Fluorescein, a non-toxic, fluorescent dye, was released inside a stocked fish cage for visualization of 3-dimensional flow patterns inside the cage. Atlantic salmon tend to form a torus shaped school and swim in a circular path, following the net during the daytime. Current measurements around an empty and a stocked fish cage show a strong influence of fish swimming in this circular pattern: while most of the oncoming water mass passes through the empty cage, significantly more water is pushed around the stocked fish cage. Dye experiments show that surface water inside stocked fish cages converges towards the center, where it sinks and spreads out of the cage at the depth of maximum biomass. Furthermore, the converging surface water swirled in the direction of the swimming fish. In order to achieve a circular motion, fish must accelerate towards the center of the cage. This inward-directed force must be balanced by an outward force that pushes the water out of the cage, resulting in a low pressure area in the center of the rotational motion of the fish. Thus, water is pulled from above and below the fish swimming depth. The laboratory tests with empty cages agree well with field measurements around empty fish cages, and give a good starting point for further laboratory tests including the effect of fish-induced currents inside the cage to document the details of the flow patterns inside and adjacent to stocked fish cages. The results of such experiments can be used as benchmarks for numerical models to simulate the water flow in and around net pens, and model the oxygen supply and the spreading of wastes in the near wake of stocked fish farms.

Flow Fields Inside Stocked Fish Cages and the Near Environment

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
Lars C. Gansel ◽  
Siri Rackebrandt ◽  
Frode Oppedal ◽  
Thomas A. McClimans
Keyword(s):  
Atlantic Salmon ◽  
Water Flow ◽  
Laboratory Tests ◽  
Numerical Models ◽  
Field Measurements ◽  
Flow Patterns ◽  
Fish Swimming ◽  
Swimming Depth ◽  
Starting Point ◽  
Fish Cages

This study explores the average flow field inside and around stocked Atlantic salmon (Salmo salar L.) fish cages. Laboratory tests and field measurements were conducted to study flow patterns around and through fish cages and the effect of fish on the water flow. Currents were measured around an empty and a stocked fish cage in a fjord to verify the results obtained from laboratory tests without fish and to study the effects of fish swimming in the cage. Fluorescein, a nontoxic, fluorescent dye, was released inside a stocked fish cage for visualization of three-dimensional flow patterns inside the cage. Atlantic salmon tend to form a torus shaped school and swim in a circular path, following the net during the daytime. Current measurements around an empty and a stocked fish cage show a strong influence of fish swimming in this circular pattern: while most of the oncoming water mass passes through the empty cage, significantly more water is pushed around the stocked fish cage. Dye experiments show that surface water inside stocked fish cages converges toward the center, where it sinks and spreads out of the cage at the depth of maximum biomass. In order to achieve a circular motion, fish must accelerate toward the center of the cage. This inward-directed force must be balanced by an outward force that pushes the water out of the cage, resulting in a low pressure area in the center of the rotational motion of the fish. Thus, water is pulled from above and below the fish swimming depth. Laboratory tests with empty cages agree well with field measurements around empty fish cages, and give a good starting point for further laboratory tests including the effect of fish-induced currents inside the cage to document the details of the flow patterns inside and adjacent to stocked fish cages. The results of such experiments can be used as benchmarks for numerical models to simulate the water flow in and around net pens, and model the oxygen supply and the spreading of wastes in the near wake of stocked fish farms.

Hydrodynamic influences on sedimentology and geomorphology of nearshore parts of carbonate ramps: Holocene, NE Yucatán Shelf, Mexico

2021 ◽  
Vol 91 (10) ◽  
pp. 1040-1066
Author(s):  
Thomas C. Neal ◽  
Christian M. Appendini ◽  
Eugene C. Rankey
Keyword(s):  
Numerical Models ◽  
Remote Sensing Data ◽  
Field Measurements ◽  
High Energy ◽  
Tidal Range ◽  
Carbonate Platforms ◽  
Trade Winds ◽  
Tidal Forces ◽  
Carbonate Ramps ◽  
Geologic Record

ABSTRACT Although carbonate ramps are ubiquitous in the geologic record, the impacts of oceanographic processes on their facies patterns are less well constrained than with other carbonate geomorphic forms such as isolated carbonate platforms. To better understand the role of physical and chemical oceanographic forces on geomorphic and sedimentologic variability of ramps, this study examines in-situ field measurements, remote-sensing data, and hydrodynamic modeling of the nearshore inner ramp of the modern northeastern Yucatán Shelf, Mexico. The results reveal how sediment production and accumulation are influenced by the complex interactions of the physical, chemical, and biological processes on the ramp. Upwelled, cool, nutrient-rich waters are transported westward across the ramp and concentrated along the shoreline by cold fronts (Nortes), westerly regional currents, and longshore currents. This influx supports a mix of both heterozoan and photozoan fauna and flora in the nearshore realm. Geomorphically, the nearshore parts of this ramp system in the study area include lagoon, barrier island, and shoreface environments, influenced by the mixed-energy (wave and tidal) setting. Persistent trade winds, episodic tropical depressions, and winter storms generate waves that propagate onto the shoreface. Extensive shore-parallel sand bodies (beach ridges and subaqueous dune fields) of the high-energy, wave-dominated upper shoreface and foreshore are composed of fine to coarse skeletal sand, lack mud, and include highly abraded, broken and bored grains. The large shallow lagoon is mixed-energy: wave-dominated near the inlet, it transitions to tide-dominated in the more protected central and eastern regions. Lagoon sediment consists of Halimeda-rich muddy gravel and sand. Hydrodynamic forces are especially strong where bathymetry focuses water flow, as occurs along a promontory and at the lagoon inlet, and can form subaqueous dunes. Explicit comparison among numerical models of conceptual shorefaces in which variables are altered and isolated systematically demonstrates the influences of the winds, waves, tides, and currents on hydrodynamics across a broad spectrum of settings (e.g., increased tidal range, differing wind and wave conditions). Results quantify how sediment transport patterns are determined by wave height and direction relative to the shoreface, but tidal forces locally control geomorphic and sedimentologic character. Similarly, the physical oceanographic processes acting throughout the year (e.g., daily tides, episodic winter Nortes, and persistent easterly winds and waves) have more impact on geomorphology and sedimentology of comparable nearshore systems than intense, but infrequent, hurricanes. Overall, this study provides perspectives on how upwelling, nutrient levels, and hydrodynamics influence the varied sedimentologic and geomorphic character of the nearshore areas of this high-energy carbonate ramp system. These results also provide for more accurate and realistic conceptual models of the depositional variability for a spectrum of modern and ancient ramp systems.

scholarly journals Randomized response surface pathway design with skewed starting point and stochastic dose window

2020 ◽  
Vol 7 (1) ◽  
pp. 18
Author(s):  
Trond Holand ◽  
Øystein Evensen ◽  
Sagita Dewi ◽  
Stig Larsen
Keyword(s):  
Atlantic Salmon ◽  
Response Surface ◽  
Initial Dose ◽  
Salt Water ◽  
Lower Boundary ◽  
Response Variable ◽  
Ct Value ◽  
Starting Point ◽  
Starting Dose ◽  
The Mean

<p class="abstract"><strong>Background:</strong> The aim was to introduce response surface pathway (RSP)-design with skewed starting value and stochastic dose-window to estimate optimal efficacy dose (OED) of BP-C2 after IL-1β stimulation in Atlantic salmon.</p><p class="abstract"><strong>Methods:</strong> 54 healthy smolt of Atlantic salmon between 50 and 100 g before habituated to salt water were included. The study was conducted as a one-dimensional, randomized between-patient three-level RSP designed trial with one interventional- and one response variable and odd outcomes. The interventional variable was intraperitoneal injected BPC2 with skewed starting dose of 0.10 mg/100 g related to the initial dose-window &lt;0.02-0.5 mg/100 g. The response variable was the Ct-value of mRNA IL-1β expression 24 hours after injection.</p><p class="abstract"><strong>Results:</strong> Skewed starting value of 0.10 mg/100 g was chosen in the first design-level with a dose-window of &lt;0.0-0.20]. The three smolt obtained a reduction in Ct-value above 15%, and the dose-window adjusted with the lower boundary equals the previous dose. The five smolt at second design-level received 0.16 mg/100g with a dose-window [0.10-0.22]. Four smolt obtained above 15% and one of 0.5% reduction in cycle threshold (Ct)-value. Six smolt in the third design-level received 0.21 mg/100 g and one 0.16 mg/100 g. The mean Ct-value was reduced from 30.0 in the unstimulated situation to 25.0, 24.8 and 26.4 after BP-C2 stimulation of 0.10, 0.16 and 0.21 mg/100 g, respectively. The OED of BP-C2 related to IL-1β was estimated to 0.14 mg/100 g.</p><p class="abstract"><strong>Conclusions: </strong>Skewed starting value in the initial dose-window made the K-adjustment factor and dose-window stochastic. The RSP-procedure works in accordance to the expectation and estimated OED of BP-C2 sufficiently.</p><strong> </strong>

scholarly journals Peranan Kontrol Struktural dan Hidrologis dalam Perkembangan Lorong Gua Bagus-Jebrot di Malang-Indonesia

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Mohammad Ainul Labib ◽  
Agung Suprianto ◽  
Devi Prasetyo ◽  
Aan Seftian Hardianto ◽  
Alfi Sahrina ◽  
...  
Keyword(s):  
Surface Water ◽  
Groundwater Flow ◽  
Cross Section ◽  
Frequency Analysis ◽  
Late Miocene ◽  
Structural Control ◽  
Middle Miocene ◽  
Field Measurements ◽  
Underground Water ◽  
And Control

Bagus-Jebrot Cave is located in Donomulyo District, Malang Regency which is in the Wonosari Formation which was formed in the Middle Miocene and Late Miocene. The purpose of this study is related to the developmental control that affects the cave passageways. The approach used is a geomorphological approach by conducting field measurements and documentation. The analysis used is frequency analysis and cross-section of the passage. Bagus-Jebrot Cave is a type of Epigenic Cave which is formed from surface water flowing into doline/sinkhole. It can be seen from the planview map that has a curvilinear passage pattern. The existence of groundwater flow also forms a physiographic cave passage with ellipse passage formation, asymmetrical ellipse, potholes, callops, solution notches, cups, solution pockets. Besides underground water flow, the development of the Bagus-Jebrot Cave aisle is related to the process of structural lifting and control. The lifting process is marked by the formation of 4 levels of the cave passage. While the formation of the canyon, joint passage, rectangular passage and keyhole is the result of structural control

scholarly journals Drag on Nets Fouled With Blue Mussel (Mytilus Edulis) and Sugar Kelp (Saccharina Latissima) and Parameterization of Fouling

2017 ◽  
Author(s):  
Lars C. Gansel ◽  
Per Christian Endresen ◽  
Kristine Braaten Steinhovden ◽  
Stine Wiborg Dahle ◽  
Eirik Svendsen ◽  
...  
Keyword(s):  
Mytilus Edulis ◽  
Structural Integrity ◽  
Blue Mussel ◽  
Numerical Models ◽  
Flow Speed ◽  
Saccharina Latissima ◽  
Detailed Knowledge ◽  
Fish Welfare ◽  
Fish Cages ◽  
The Relationship

Biofouling is a serious problem in marine finfish aquaculture with a number of negative impacts. Marine growth obstructs net openings, thereby reducing water exchange through the net and affecting fish welfare and health, as well as the spreading of dissolved nutrients, particles and pathogens. Furthermore, additional water blockage leads to increased hydrodynamic forces on fish cages, which potentially threaten the structural integrity of the fish farm. However, detailed knowledge about the effects of biofouling on the flow past, and the resulting forces on fish cages, is limited and systematic investigations of the effects of different types of fouling have been called for. This study investigates the effects of different amounts and sizes of two important fouling organisms in Norwegian aquaculture, blue mussel (Mytilus edulis) and kelp (Saccharina latissima) on the drag on net panels. Drag forces on a number of clean and fouled nets were measured in a flume tank at a flow speed of 0.1 m/s. Net solidity was calculated from images acquired of all nets in the current. The relationship between net solidity and drag was then found for clean nets and for each type of fouling, and biofouling was parameterized by comparing clean and fouled net results: for a given fouled net, a clean net can be found that experiences the same drag. The latter can then be used in numerical models to estimate the effect of fouling on net drag. That means existing models can be used to model the drag effect of fouling. This study found a solidity increase due to mussel and kelp fouling to affect drag roughly at the same rate as an increase in clean net solidity at a flow speed of 0.1 ms−1 and within the tested fouling size range for two net types. Therefore, existing models, describing the relationship between net solidity and drag, can be used directly or with minor alterations (especially at high solidities) to estimate effects of additional mussel and kelp fouling on drag. In contrast, wet weight seems to be unsuitable as a measure to estimate drag on nets fouled with seaweed or mussels. It should be noted that these findings are only valid under similar conditions, and that other fouling types and sizes, as well as test parameters and tank size can affect the relationship between solidity and drag.

Industrial pollution and vegetable farming in sharada industrial layout of Kano municipal area council

2021 ◽  
Vol 1 (2) ◽  
pp. 50-58
Author(s):  
Ikenna Uzonu
Keyword(s):  
Surface Water ◽  
Environmental Protection Agency ◽  
Industrial Effluents ◽  
Field Measurements ◽  
Secondary Treatment ◽  
Protection Agency ◽  
Vegetable Farmers ◽  
Groundwater Samples ◽  
Dug Wells ◽  
Vegetable Farming

This work examined the effects of industrial effluents on surface water used for vegetable irrigation in Kano City of Kano State. As the population of Kano increases, more demand is placed on these industries for products thus leading to the generation of large volumes of effluents that are discharged directly into nearby streams without treatment. The usage of this surface water for vegetable irrigation by a significant number of vegetable farmers is a matter of major concern due to the presence of pollutants. Some of the field measurements were carried out insitu while others were taken to the laboratory for analysis. Groundwater samples were taken from a borehole and two hand-dug wells while surface water was taken from point of discharge and two other points along the Challawa River which is the main source of water for vegetable irrigation. Composite soil samples were taken from four points within the vegetable farms. The Federal Environmental Protection Agency and the Federal Ministry of Environment standards were used as baseline standards for limits. Results show that presence of Fe, Pb, Mn, Cr and Cd were found to be above the FMEnv limits in the soil, the presence of SO4, Cu and K were also found to be above the FMEnv limits as well in groundwater while BOD, NO2 and Cr were above the FEPA limit for surface water. Some of the recommendations include constant monitoring for the presence of heavy metals in soils and irrigation water and that the need for the construction of both primary and secondary treatment plants has become essential.

scholarly journals Atlantic salmon post-smolt migration routes in the Gulf of St. Lawrence

2012 ◽  
Vol 69 (6) ◽  
pp. 981-990 ◽  
Author(s):  
Marylise A. Lefèvre ◽  
Michael J. W. Stokesbury ◽  
Frederick G. Whoriskey ◽  
Michael J. Dadswell
Keyword(s):  
Surface Water ◽  
Atlantic Salmon ◽  
Atlantic Ocean ◽  
Salmo Salar ◽  
Swimming Speed ◽  
Migration Routes ◽  
Water Currents ◽  
North Shore ◽  
The North ◽  
Residency Time

Abstract Lefèvre, M. A., Stokesbury, M. J. W., Whoriskey, F. G., and Dadswell, M. J. 2012. Atlantic salmon post-smolt migration routes in the Gulf of St. Lawrence – ICES Journal of Marine Science, 69: 981–990. The migration of Atlantic salmon (Salmo salar) post-smolts from the Rivière Saint-Jean on the north shore of the Gulf of St. Lawrence (Canada) was studied during 2009 and 2010. Salmon from rivers in this region spend ≥2 years at sea before returning to spawn, and are believed to migrate to ocean feeding areas off Greenland. To determine residency time in the nearshore environment, and to define the migration routes of post-smolts, tagged post-smolts were tracked passively in Jacques Cartier Strait and at the two exits of the Gulf of St. Lawrence to the Atlantic Ocean (Cabot Strait and the Strait of Belle Isle). Post-smolts moved rapidly south in the nearshore area; two of them were detected 45 km south of the estuary exit, suggesting that they were moving towards the centre of the Gulf of St. Lawrence. One tagged post-smolt was detected exiting the Gulf of St. Lawrence via the Strait of Belle Isle after 44 d and exhibited a minimum swimming speed of 14.4 km d−1. There was no apparent linkage between the detection patterns of post-smolts and surface water temperatures or surface water currents close to shore. Post-smolts, however, appeared to orient to higher salinity.

Fish cage and mooring system dynamics using physical and numerical models with field measurements

2003 ◽  
Vol 27 (2) ◽  
pp. 117-146 ◽  
Author(s):  
David W. Fredriksson ◽  
M.Robinson Swift ◽  
James D. Irish ◽  
Igor Tsukrov ◽  
Barbaros Celikkol
Keyword(s):  
System Dynamics ◽  
Numerical Models ◽  
Field Measurements ◽  
Mooring System
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