The herring swimbladder: loss and gain of gas

1984 ◽  
Vol 64 (2) ◽  
pp. 441-459 ◽  
Author(s):  
J. H. S. Blaxter ◽  
R. S. Batty
Keyword(s):  
Pressure Vessel ◽  
Atmospheric Pressure ◽  
Juvenile Fish ◽  
Gas Diffusion ◽  
Sea Surface ◽  
Target Strength ◽  
Experimental Conditions ◽  
Neutral Buoyancy ◽  
Sea Bed ◽  
Ecological Implications

The herring is a physostome with no gas secretion mechanism in the swimbladder. The swimbladder volume was measured in fish from about 3–33 cm in length. It was rarely large enough to give the fish neutral buoyancy at the sea surface. Swimbladder volumes were also measured after periods of up to 1 week at pressures from 1·9 to 5·5 ATA (0·9–4·5atm above atmospheric pressure) in a laboratory pressure vessel and in a sub-surface cage in the sea. The swimbladder gas was lost within a few hours in the larval herring and in a few days in smaller juvenile fish; no change was found in older fish under experimental conditions. The findings were in accord with measurements of the guanine content of the swimbladder wall which was low in those fish which lost gas quickly. This supports the view that gas diffusion is limited by guanine crystals. While it seems likely that larger fish can exist for several weeks without the need to replenish the swimbladder gas some large spawning herring were caught at sea with empty swimbladders, suggesting a long stay near the sea bed. Analysis of swimbladder gas showed that oxygen tended to diffuse out more quickly than nitrogen. Behaviour experiments showed that fish with artificially emptied swimbladders could refill them by swallowing air at the surface, in some cases very quickly and efficiently. Fish with empty swimbladders and no access to the surface suffered a high mortality. The ecological implications of these results and their relevance to the interpretation of sonar ‘target strength’ measurements are discussed.

scholarly journals The contribution of Geomatics to increase safety and security in ports

2021 ◽  
Author(s):  
Maurizio Soldani
Keyword(s):  
Atmospheric Pressure ◽  
Research Team ◽  
Environmental Parameters ◽  
Sea Surface ◽  
Port Security ◽  
Process Data ◽  
Water Quality Control ◽  
Port Authorities ◽  
Graphical Interfaces ◽  
Port Areas

AbstractIn this paper, the advantages achievable from the use of two prototype systems that are being developed to increase safety and security in ports are shown. Both systems start by monitoring environmental parameters in harbors, and then process data acquired. The first system has been conceived to be helpful to port communities (port authorities, pilots) to optimize harbor waterside management (ship’s navigation and cargo, dock performances, boat moorings, refloating of stranded ships, water quality control). By monitoring and processing sea level and atmospheric pressure in port areas, it can help port communities, e.g., to choose the best time when a ship with a certain draft can enter or leave a harbor, or to plan the best route inside the basin for that vessel (port safety). The second system, instead, has been designed for port protection purposes: by monitoring and processing the Earth’s magnetic field below the sea surface in harbors (where the natural field is disturbed by a high artificial component), it is able to detect the possible presence of intruders (e.g., divers) swimming underwater in prohibited areas (port security). Here, the results of monitoring and processing activities of the two systems performed in Livorno and La Spezia harbors are shown (Italy). The processing procedures and the graphical interfaces of the systems are based on applications under development by the research team the author belongs to, by using C# and C++ languages; Matlab environment has been employed for simulations.

scholarly journals Tunning CO2 Separation Performance of Ionic Liquids through Asymmetric Anions

Molecules ◽  
2022 ◽  
Vol 27 (2) ◽  
pp. 413
Author(s):  
Bruna F. Soares ◽  
Daniil R. Nosov ◽  
José M. Pires ◽  
Andrey A. Tyutyunov ◽  
Elena I. Lozinskaya ◽  
...  
Keyword(s):  
Ionic Liquids ◽  
Atmospheric Pressure ◽  
Time Lag ◽  
Gas Permeation ◽  
Separation Performance ◽  
Experimental Conditions ◽  
Feed Pressure ◽  
Similar Chemical ◽  
Supported Ionic Liquid Membranes ◽  
Gas Separation Performance

This work aims to explore the gas permeation performance of two newly-designed ionic liquids, [C2mim][CF3BF3] and [C2mim][CF3SO2C(CN)2], in supported ionic liquid membranes (SILM) configuration, as another effort to provide an overall insight on the gas permeation performance of functionalized-ionic liquids with the [C2mim]+ cation. [C2mim][CF3BF3] and [C2mim][CF3SO2C(CN)2] single gas separation performance towards CO2, N2, and CH4 at T = 293 K and T = 308 K were measured using the time-lag method. Assessing the CO2 permeation results, [C2mim][CF3BF3] showed an undermined value of 710 Barrer at 293.15 K and 1 bar of feed pressure when compared to [C2mim][BF4], whereas for the [C2mim][CF3SO2C(CN)2] IL an unexpected CO2 permeability of 1095 Barrer was attained at the same experimental conditions, overcoming the results for the remaining ILs used for comparison. The prepared membranes exhibited diverse permselectivities, varying from 16.9 to 22.2 for CO2/CH4 and 37.0 to 44.4 for CO2/N2 gas pairs. The thermophysical properties of the [C2mim][CF3BF3] and [C2mim][CF3SO2C(CN)2] ILs were also determined in the range of T = 293.15 K up to T = 353.15 K at atmospheric pressure and compared with those for other ILs with the same cation and anion’s with similar chemical moieties.

In situ acoustic estimates of the swimbladder volume of Atlantic herring (Clupea harengus)

2004 ◽  
Vol 61 (3) ◽  
pp. 323-337 ◽  
Author(s):  
Redwood W. Nero ◽  
Charles H. Thompson ◽  
J. Michael Jech
Keyword(s):  
Gulf Of Maine ◽  
Clupea Harengus ◽  
Sea Surface ◽  
Atlantic Herring ◽  
Acoustic Measurements ◽  
Neutral Buoyancy ◽  
Fish Weight ◽  
Neutrally Buoyant ◽  
Boyle’S Law

Abstract Acoustic measurements at 1.5–5 kHz on fish in the Gulf of Maine showed a swimbladder-resonance peak near 2.5 kHz at 160–190-m depth. Midwater trawls confirmed that the fish were likely to be Atlantic herring (Clupea harengus) of 19–29 cm length. Calculation using a model of swimbladder resonance gives swimbladder volumes of 1.2% of fish weight at 160–190 m. Extrapolation of this volume of gas using Boyle's Law suggests that at the sea surface, these herring would need to inflate their swimbladders by up to five to six times the volume required for neutral buoyancy. If these fish were to maintain this volume of gas with surface “gulping”, they would need to submerge from the sea surface with a 30% excess buoyancy. In general, swimbladders of the Clupeidae may have greater volumes of gas than if the fish were neutrally buoyant at the sea surface and the interpretation of HF-echosounder surveys may be additionally complex when the volume of gas and swimbladder volume are difficult to predict. Mechanisms of how herring obtain additional swimbladder gas are discussed.

scholarly journals Gastrointestinal parasites in feral cats and rodents from the Fernando de Noronha Archipelago, Brazil

2017 ◽  
Vol 26 (4) ◽  
pp. 521-524 ◽  
Author(s):  
Victor Fernando Santana Lima ◽  
Rafael Antonio Nascimento Ramos ◽  
Raphael Lepold ◽  
João Carlos Gomes Borges ◽  
Carlos Diógenes Ferreira ◽  
...  
Keyword(s):  
Human Infection ◽  
Gastrointestinal Parasites ◽  
Parasitic Infections ◽  
Toxocara Cati ◽  
Experimental Conditions ◽  
Trichuris Muris ◽  
Feral Cats ◽  
Ecological Implications ◽  
Fernando De Noronha ◽  
Parasite Infections

Abstract Gastrointestinal parasites are important pathogens affecting animals, some of them are of medical and veterinary concern. Although the dynamic of parasitic infections is a complex phenomenon that has been studied under experimental conditions, it shows several gaps in knowledge, especially in insular regions where a confined population of animals and parasites co-exists. In this study was assessed the parasitism by endoparasite gastrointestinal in feral cats (n = 37) and rodents (n = 30) from the Fernando de Noronha Archipelago; in addition, the risk of human infection and ecological implications of these findings were discussed. Out of all samples analysed, 100% scored positive for the presence of gastrointestinal parasites in both feral cats and rodents. A total 17 genera and/or species of endoparasite gastrointestinal were identified, Ancylostoma sp., Strongyloides sp., Trichuris campanula and Toxocara cati were the parasites more frequently in feral cats. In rodents Eimeria sp., Strongyloides sp. and Trichuris muris were parasites more frequently herein detected. Human population living in this area are at risk of parasite infections due to the population of rodents and feral cats in the archipelago.

Growth Mechanism and Optical Properties of Nano and Microstructures of ZnO Obtained by Thermal Oxidation of Zinc Powders at Atmospheric Pressure

2019 ◽  
Vol 286 ◽  
pp. 33-39
Author(s):  
Carlos Bueno ◽  
Abraham Pacio ◽  
Edith Osorio ◽  
Jose Alberto Alvarado ◽  
David Maestre ◽  
...  
Keyword(s):  
Thermal Oxidation ◽  
Growth Mechanism ◽  
Atmospheric Pressure ◽  
Hollow Spheres ◽  
Emission Spectra ◽  
Green Emission ◽  
Bottom Surface ◽  
Deep Part ◽  
Experimental Conditions ◽  
Zinc Powders

ZnO Nano and microstructures were obtained by thermal oxidation using Zn powders as source. To achieve those structures, the Zn powders were annealed at 650°C and 750°C under oxygen environment and atmospheric pressure. SEM results show that these experimental conditions promote the formation of hollow spherical microstructures with nanowires and nano-swords in each sphere. As was observed, the nanostructures start growing from the bottom surface of the spheres unlike those that were reported recently. The EDS results clearly show that those hollow spheres in the deep part make a compound with Zn and the top surface is mainly composed of ZnO. CL emission spectra show a main green emission that belongs to the sphere’s bottom surface; this emission is correlated to the existing defects that are presented. These results could allow the prediction of a possible growth mechanism under specific conditions.

Experimental Method for Determining the Damping Parameter of Spectral Lines Emitted by a Microwave Plasma at Atmospheric Pressure

2005 ◽  
Vol 59 (12) ◽  
pp. 1457-1464 ◽  
Author(s):  
I. Santiago ◽  
M. C. García ◽  
M. D. Calzada
Keyword(s):  
Line Profile ◽  
Atmospheric Pressure ◽  
Microwave Plasma ◽  
Argon Plasma ◽  
Spectral Lines ◽  
Experimental Conditions ◽  
Simple Method ◽  
Damping Parameter ◽  
Absorption Phenomenon ◽  
Parameter Values

In this work, a simple method for experimentally obtaining the value of the damping parameter or a-parameter of the spectral lines emitted by an argon plasma generated at atmospheric pressure is presented. The value of this coefficient indicates the proportion existing between the Lorentzian and Doppler components of the total line profile, which can be approximated to a Voigt function for our experimental conditions. The a-parameter values found were within the value interval recorded in the literature. The results obtained showed that the damping coefficient of the lines next to the fundamental level remains practically constant along the plasma column, whereas for the spectral lines involving high-lying levels, the a-parameter is sensitive to the changes in the electron density in the plasma. In this work it is also proved that the self-absorption phenomenon induces errors in the calculation of a, due to an increase in the broadening of the line profile produced by this phenomenon.

scholarly journals Derivation of Three-Dimensional Radiation Stress Based on Lagrangian Solutions of Progressive Waves

2017 ◽  
Vol 47 (11) ◽  
pp. 2829-2842 ◽  
Author(s):  
Chao Ji ◽  
Qinghe Zhang ◽  
Yongsheng Wu
Keyword(s):  
Coordinate Transformation ◽  
Atmospheric Pressure ◽  
Three Dimensional ◽  
Sea Surface ◽  
Lagrangian Description ◽  
Radiation Stress ◽  
New Approach ◽  
Progressive Waves ◽  
Analytical Expressions ◽  
Sloping Bottom

AbstractA new approach has been proposed to derive the expressions for three-dimensional radiation stress using solutions of the pressure and velocity distributions and the coordinate transformation function that are derived from a Lagrangian description wherein the pressure is zero (relative to the atmospheric pressure) at the sea surface. Using this approach, analytical expressions of horizontal and vertical depth-dependent radiation stress are derived at a uniform depth and for a sloping bottom, respectively. The results of the depth integration of the expressions agree well with the theory of Longuet-Higgins and Stewart. In the case involving a sloping bottom, the radiation stress expressions from this study provide a better balance of the net momentum compared to those from previous studies.

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