Experiments on Substrate Selection by Corophium Species: Films and Bacteria on Sand Particles

1964 ◽  
Vol 41 (3) ◽  
pp. 499-511
Author(s):  
P. S. MEADOWS

1. A simple method is described for determining the substrate preferences of Corophium volutator (Pallas) and Corophium arenarium Crawford. 2. If offered a choice of its own substrate with that of the other species each prefers its own. 3. Level of illumination and colour of substrate have little effect on choice. An animal's size and hence its age has little effect on its substrate preferences. 4. C. volutator prefers a substrate previously maintained under anaerobic conditions, C. arenarium vice versa. 5. Treatments which kill, inactivate, or remove micro-organisms render sands unattractive to Corophium. These include boiling, acid-cleaning, drying, and soaking in fixatives or distilled water. Attempts to make these sands attractive again failed. 6. Distilled water, and solutions of the non-electrolytes sucrose and glycerol at the same osmotic pressure as sea water, induce many bacteria to desorb from sand particles; smaller numbers are desorbed in the presence of solutions of electrolytes at the same ionic strength as sea water (NaCl, Na2SO4, KC1, MgSO4, MgCl2, CaCl2). Of all these, only distilled water and solutions of MgCl2 and CaCl2 reduce the attractive properties of sands. Hence the loss of bacteria from the surface of sand grains, though related to the ionic strength and composition of the medium, is not necessarily associated with a substrate becoming unattractive.

1995 ◽  
Vol 32 (5) ◽  
pp. 767-782 ◽  
Author(s):  
R.C. Joshi ◽  
Gopal Achari ◽  
Shenbaga R. Kaniraj ◽  
H. Wijeweera

The main objective of this study was to understand the effect of aging on the penetration resistance of freshly deposited sands. Two types of sand, locally available river sand used as masonry sand and Beaufort Sea sand, were selected for the study. The sands were allowed to age under a constant stress of 100 kPa in a specially designed apparatus in a dry state, as well as submerged in distilled water and in simulated sea water. Penetration resistance of the sand beds was measured periodically by pushing 4 probes into the sand bed. Mineralogical and fabric studies on freshly deposited and aged sand samples were conducted to detect the effect of aging, if any, on sand grains. The results indicate that aging significantly increases the penetration resistance of sands. The rate of increase in penetration resistance was higher for the submerged sand as compared with the dry sand. The increase in penetration resistance of the sand in a dry state was attributed to rearrangement of sand grains. In the submerged state, besides the rearrangement of sand particles, partial cementation caused by precipitation of salts and probably also silica on the sand grains and in the pores resulted in the larger increase in the penetration resistance. Key words : sand, aging, penetration resistance, freezing and thawing, sea water, distilled water.


1971 ◽  
Vol 125 (1) ◽  
pp. 297-302 ◽  
Author(s):  
Thérèse Ternynck ◽  
Stratis Avrameas

Specific immune precipitates dissolve in concentrated solutions of alkali-metal halides, and of alkaline-earth-metal halides and thiocyanates. The quantity of protein dissolved depends on the nature of the antigen–antibody system, on the proportion of the antigen in the precipitate, and on the avidity of the antibody. The extent of solubilization is a function of the temperature, of the volume of solution used and of the concentration of the ions in the solution, and also depends on the nature of these ions. The dissolving power of bivalent cations is greater than that of monovalent ones, and is as follows: Mg2+[unk]Ba2+[unk]Ca2+[unk]Sr2+. Antigen–antibody complexes and free antibodies, but no free antigen, are detected in supernatants of specific precipitates dissolved in solutions of electrolytes of low ionic strength. Antigen–antibody complexes, free antibodies and also free antigen are detected in supernatants of specific precipitates dissolved in solutions of electrolytes of high ionic strength. Comparable results are obtained when the electrolyte solutions are studied for their effect on the bonds formed between an antibody and its corresponding immunosorbent. Moreover, in the latter case, 50% of the fixed antibodies could be recovered by elution with distilled water.


1992 ◽  
Vol 25 (11) ◽  
pp. 117-124 ◽  
Author(s):  
N. Watanabe ◽  
S. Sakai ◽  
H. Takatsuki

Examination of individual degradation paths (biodegradation and photolysis) of butyltin compounds (especially tributyltin: TBT) in natural waters was performed. Biodegradation of TBT and dibutyltin (DBT) in an unfiltered sea water in summer is rather fast; their half life is about a week. But pretreatment with glass fiber filter makes the half life of TBT much longer (about 80 days). Photolysis of TBT in sea water by sun light is rapid (half life is about 0.5 days), and faster than in distilled water or in fresh water. Degradation rates of each process for TBT are calculated in various conditions of sea water, and contribution rates are compared. Biodegradation will be the main degradation process in an “SS-rich” area such as a marina, but photolysis will exceed that in a “clean” area. Over all half lives of TBT in sea water vary from 6 days to 127 days considering seasons and presence of SS.


2021 ◽  
Vol 9 (6) ◽  
pp. 634
Author(s):  
Euichi Hirose ◽  
Noburu Sensui

Ascidians are marine sessile chordates that comprise one of the major benthic animal groups in marine ecosystems. They sometimes cause biofouling problems on artificial structures underwater, and non-indigenous, invasive ascidian species can potentially and seriously alter native faunal communities. Ascidian larvae are usually tadpole-shaped, negatively phototactic, and adhere on substrates by secreting a glue from their adhesive organs. Although larvae often prefer hydrophobic surfaces, such as a silicone rubber, for settlement, hydrophobic materials are often used to reduce occurrence of fouling organisms on artificial structures. This inconsistency may indicate that an attractive surface for larvae is not always suitable for settlement. Micro-scale structures or roughness may enhance the settlement of ascidian larvae, but settlement is significantly reduced by a nano-scale nipple array (or moth-eye structure), suggesting functional properties of similar structures found on the body surfaces of various invertebrates. The substrate preferences of larvae should be one of the important bases in considering measures against biofouling, and this review also discusses the potential uses of materials to safely reduce the impacts of invasive species.


2017 ◽  
Vol 130 (1) ◽  
pp. 479-484 ◽  
Author(s):  
M. M. Mato ◽  
L. M. Casás ◽  
J. L. Legido ◽  
C. Gómez ◽  
L. Mourelle ◽  
...  

1963 ◽  
Vol 40 (1) ◽  
pp. 187-193
Author(s):  
M. J. WELLS

1. A method of teaching Octopus chemotactile discriminations is described. 2. The animals can be shown to be capable of distinguishing by touch between porous objects soaked in plain sea water and sea water with hydrochloric acid, sucrose or quinine sulphate added. 3. They can detect these substances in concentrations at least 100 times as dilute as the human tongue is capable of detecting them in distilled water. 4. They can be trained to distinguish between equimolar (0.2 mM) solutions of hydrochloric acid, sucrose and quinine. 5. They can also be trained to distinguish between sea water and fresh water or half-strength sea water or sea water with twice the usual quantity of salt. 6. The function of the ‘olfactory organ’ is discussed. 7. Chemotactile learning is discussed in relation to the means by which Octopus finds its way about the territory around its ‘home’


Author(s):  
O. Shkromada ◽  
Yu. Dudchenko ◽  
T. Necherya ◽  
I. Abubakari Kavla

In this field, complex disinfectants were contrasted using effective concentrations against bacteria and spore-forming microorganisms. A significant problem for the owners is the emergence of resistance of strains of microorganisms in the existing production and the same disinfectants. Investigation of trusted working concentrations of disinfectants that do not have a corrosive effect on metal structures. According to the results of research and production, contrast is an effective disinfectant for reducing E. coli and S aureus at 0,3 – 0,5% concentration at exposure for 30 min. and consumption of 100 - 400 cm3 / m2. Laboratory researches were carried out in laboratories of microbiological faculties of veterinary medicine of Sumy National Agrarian University. Disappearance gaps and disinfection on the market in Kyiv. Samples were drawn in the refrigerators from the walls, ceilings and floors. Refrigerated chambers made of stainless steel are made up of rubber and plastic elements. Metals are very vulnerable to corrosion with more concentrated acids and alkali. This was taken into account when choosing a disinfectant and its effective organizations. As a disinfectant used the drug contrast (manufacturer PE "Kronos Agro", Ukraine). The disinfectant was taken at a dose of 100 ml per 1 m2. To produce the culture was prepared basic products containing 1000 mg of the drug in 1 ml of distilled water. The experimental solutions were prepared for study with the main formulations developed. Representatives had extraordinary effects. The  disks were leaked through the disinfectant to obtain a zone of retention of high bacteria and fungi. The reliability of disinfectant destroying the micro-organisms of E. coli and S. aureus test cultures was also known. For the trusted production preparations, the contrast at the trusted enterprises was carried out by the rehabilitation of the premises of the educational laboratory of the Sumy National Agrarian University (premises for animals, dairies, refrigeration chambers). Renovation and test activities were performed at 0,1, 0,25 and 0,5 % of exposed contrast with exposure for 60, 30 and 10 min. the disinfectant was consumed 250 cm3 / m2. Upon completion of the studies, the investigated tests were investigated with distilled water (flow rate - 1000 cm3 / m2). Water that has been washed away test products, presented in specially prepared capabilities. Test results for this after disinfection were also investigated with distilled water, which was found on the disinfectant. To study the corrosion activity of the disinfectant used metal plates 1h1sm2. The metal samples were welded to the fifth mark after the commission before and after the study. 0,5; 1,0; 1,5; 2,5 % contrast solutions were used in the study. For comparison, in the experiments used 2% of productive. M. bovis mycobacterial cultures were grown on Pavlovsky's glycerol medium. The bacterial culture was transferred into sterile vials and sterile isotonic material containing 0,05 cm3 / mg was added. A large amount of delay zone in Petri dishes containing 0,5 % of S. aureus disinfectant, 3,5 times S. cholerase 1,8 S. Enteritidis 2 more than 0,5% formal form . Higher indicators of bacterial properties of the disinfectant contrast at a concentration of 0,5%.


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