Adaptation of the silver eel (Anguilla anguilla L.) to sea water and to artificial media together with observations on the role of the gut

1964 ◽  
Vol 11 (1) ◽  
pp. 19-30 ◽  
Author(s):  
Brenda M. Sharratt ◽  
D. Bellamy ◽  
I.Chester Jones
Keyword(s):  
Sea Water ◽  
Anguilla Anguilla ◽  
Silver Eel

MEASUREMENT OF PLASMA CORTISOL LEVELS IN THE EEL ANGUILLA ANGUILLA IN RELATION TO OSMOTIC ADJUSTMENTS

1971 ◽  
Vol 50 (1) ◽  
pp. 75-96 ◽  
Author(s):  
J. N. BALL ◽  
I. CHESTER JONES ◽  
M. E. FORSTER ◽  
G. HARGREAVES ◽  
E. F. HAWKINS ◽  
...  
Keyword(s):  
Plasma Cortisol ◽  
Sea Water ◽  
Anguilla Anguilla ◽  
Plasma Cortisol Level ◽  
Hormonal Control ◽  
Total Cortisol ◽  
Competitive Protein Binding ◽  
Low Levels ◽  
Cortisol Levels

SUMMARY The competitive protein-binding radioassay (CPB method) of Murphy (1967) has been adapted to determine total cortisol levels in the plasma of the eel, Anguilla anguilla L. Validation of the method for this species depended in part on the development of a chromatographic—fluorimetric technique for eel cortisol, following classical procedures and using radioactive tracers; by this means, the specificity of the CPB method for cortisol in eel plasma was established. Accuracy, precision and sensitivity of the CPB method were also investigated and were shown to be satisfactory. Plasma total cortisol levels were determined in eels during osmotic adjustments after transfers from fresh water (FW) to sea-water (SW) and vice versa, and from FW to distilled water. Plasma osmotic pressure and/or sodium levels were monitored simultaneously, to follow the progress of osmotic regulation. In only one of the transfer situations did the plasma cortisol level change significantly, showing a marked transitory increase during the first few days after transfer from FW to SW, corresponding to the development and correction of an 'osmotic crisis'. Plasma cortisol levels were the same in eels adapted for long periods to FW and to SW. Plasma cortisol fell to extremely low levels after hypophysectomy. These results are discussed in the light of the literature on hormonal control of osmoregulatory mechanisms in the eel, with particular emphasis on the role of adrenocorticosteroids in ionic regulation of animals in SW.

The Kinetics of Peripheral Exchanges of Water and Electrolytes in the Silver Eel (Anguilla Anguilla L.) in Fresh Water and in Sea Water

1972 ◽  
Vol 57 (2) ◽  
pp. 489-512
Author(s):  
R. KIRSCH
Keyword(s):  
Sea Water ◽  
External Medium ◽  
Anguilla Anguilla ◽  
Osmotic Gradient ◽  
Silver Eel ◽  
Experimental Tank ◽  
Experimental Conditions ◽  
Control Measurement ◽  
Internal Medium ◽  
Kinetics Of

1. New experimental techniques are described for the investigation of water and electrolyte fluxes in the eel by studying the internal medium, the urine and the external medium. An experimental tank made up of two compartments isolates the water containing the head from the water containing the trunk and tail of the animal. The two water circuits are separated by remote control. Measurement can thus be made without handling the eel previously adapted to experimental conditions. 2. The freshwater eel shows low branchial exchanges and low chloride urinary losses. A positive correlation between urinary excretion of water and sodium has been shown. 3. The silver eel's skin is impermeable to water and chlorides. 4. The eel reacts to FW-SW transfer by immediately drinking water. The drinking reflex is therefore not triggered by dehydration due to the osmotic gradient. 5. During SW adaptation the eel presents a transitory hyperactivity phase of the branchial outflux corresponding to plasma hypermineralization. 6. The eel which has been adapted to sea water for 3 weeks shows the lowest chloride exchanges ever recorded among marine teleosts.

Plasma concentrations of ovarian steroids in the freshwater European silver eel (Anguilla anguilla L.): effects of hypophysectomy and transfer to sea water

1987 ◽  
Vol 114 (2) ◽  
pp. 289-294 ◽  
Author(s):  
B. Quérat ◽  
K. Nahoul ◽  
A. Hardy ◽  
Y. A. Fontaine ◽  
J. Leloup-Hâtey
Keyword(s):  
Plasma Levels ◽  
Sea Water ◽  
Plasma Concentrations ◽  
Anguilla Anguilla ◽  
Aromatase Activity ◽  
Silver Eel ◽  
Ovarian Steroids ◽  
Silver Eels ◽  
Dependent Inhibition ◽  
Stimulation Of

ABSTRACT Intact and hypophysectomized freshwater (FW) silver eels were transferred to tanks of FW or artificial sea water (SW; salinity = 0·60 osmol/l) which were simultaneously renewed twice a week. Fish were killed 2 months after transfer and plasma was assayed for ovarian steroids. In all fish, 5α-androstane-3β,17β-diol was present, while 5α-dihydrotestosterone and 5α-androstane-3α,17β-diol were undetectable. In intact FW eels, plasma levels of testosterone, 5α-androstane-3β,17β-diol and oestradiol-17β were approximately 0·15 nmol/l. In intact SW eels, no change in plasma levels of testosterone and 5α-androstane-3β,17β-diol was found, whereas the concentration of oestradiol-17β was increased significantly (P<0·01), indicating stimulation of aromatase activity. In hypophysectomized compared with intact FW fish, plasma levels of testosterone and 5α-androstane-3β,17β-diol were decreased (P<0·05) and there was a slight but significant (P<0·01) augmentation of the plasma concentration of oestradiol-17β which may have involved the removal of pituitary-dependent inhibition of aromatase activity, possibly by 5α-reduced compounds. In hypophysectomized compared with intact SW fish, plasma levels of testosterone, 5α-androstane-3β,17β-diol and oestradiol-17β were decreased (P<0·05); in the case of oestradiol-17β, this may have reflected the diminished ovarian synthesis of testosterone, its precursor. The plasma level of oestradiol-17β was, however, higher in SW than in FW fish, even in hypophysectomized eels. This suggests that extra-pituitary mechanisms mediate, at least partly, the effects of transfer to SW on aromatase activity. J. Endocr. (1987) 114, 289–294

The role of mucus in ion absorption by the oesophagus of the sea-water eel (Anguilla anguilla L.)

1987 ◽  
Vol 157 (2) ◽  
pp. 187-199 ◽  
Author(s):  
V. Simonneaux ◽  
J. A. Barra ◽  
W. Humbert ◽  
R. Kirsch
Keyword(s):  
Sea Water ◽  
Anguilla Anguilla ◽  
Ion Absorption

scholarly journals Role of Restored Underwater Images in Underwater Imaging Applications

2021 ◽  
Vol 4 (4) ◽  
pp. 96
Author(s):  
Jarina Raihan A ◽  
Pg Emeroylariffion Abas ◽  
Liyanage C De Silva
Keyword(s):  
Machine Learning ◽  
Image Classification ◽  
Feature Detection ◽  
Sea Water ◽  
Learning Algorithm ◽  
Underwater Imaging ◽  
Underwater Image ◽  
Common Problems ◽  
Restoration Method

Underwater images are extremely sensitive to distortion occurring in an aquatic underwater environment, with absorption, scattering, polarization, diffraction and low natural light penetration representing common problems caused by sea water. Because of these degradation of quality, effectiveness of the acquired images for underwater applications may be limited. An effective method of restoring underwater images has been demonstrated, by considering the wavelengths of red, blue, and green lights, attenuation and backscattering coefficients. The results from the underwater restoration method have been applied to various underwater applications; particularly, edge detection, Speeded Up Robust Feature detection, and image classification that uses machine learning. It has been shown that more edges and more SURF points can be detected as a result of using the method. Applying the method to restore underwater images in image classification tasks on underwater image datasets gives accuracy of up to 89% using a simple machine-learning algorithm. These results are significant as it demonstrates that the restoration method can be implemented on underwater system for various purposes.

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