Marine Fish Cages—The Physical Environment

1976 ◽  
Vol 75 (4) ◽  
pp. 207-221 ◽  
Author(s):  
A. Edwards ◽  
D. J. Edelsten
Keyword(s):  
Dissolved Oxygen ◽  
Oxygen Concentration ◽  
Marine Fish ◽  
West Coast ◽  
Physical Environment ◽  
Stocking Density ◽  
Current Speed ◽  
Low Oxygen ◽  
Fish Stocking ◽  
Small Areas

SYNOPSISThe distributions of the four variables—temperature, salinity, currents and dissolved oxygen—are discussed with particular reference to the Scottish west coast. In fjords, the distributions are related to the sources of change—tides, freshwater runoff, winds and, in the case of currents, to friction, which makes currents very variable over small areas. Current speed in floating cages has been found less than that outside. A model of the oxygen concentration in such a cage has been used to examine the conditions of current and fish stocking density under which the cage can be operated without reaching dangerously low oxygen concentrations.

scholarly journals Testate amoebae (Amoebozoa: Arcellinidae) as indicators of dissolved oxygen concentration and water depth in lakes of the Lacandón Forest, southern Mexico

2019 ◽  
Vol 79 (1) ◽  
Author(s):  
Norma Fernanda Charqueño Celis ◽  
Martin Garibay ◽  
Itzel Sigala ◽  
Mark Brenner ◽  
Paula Echeverria-Galindo ◽  
...  
Keyword(s):  
Dissolved Oxygen ◽  
Oxygen Concentration ◽  
Water Depth ◽  
Diversity Index ◽  
Testate Amoebae ◽  
Sediment Surface ◽  
Ambient Conditions ◽  
Low Oxygen ◽  
Southern Mexico ◽  
Oxygen Concentrations

The ecology of aquatic protists such as testate amoebae is poorly known worldwide, but is almost completely unknown in lakes of the northern Neotropics. To address this knowledge gap, we analyzed testate amoebae (Amoebozoa: Arcellinidae) in lakes of the Lacandón Forest, one of the most biodiverse parts of southern México. We set out to evaluate the diversity of testate amoebae communities and assess whether testate amoebae taxa are reliable indicators of environmental variables dissolved oxygen and water depth. We collected 17 surface sediment samples from a range of water depths in six lakes across the Naha-Metzabok Biosphere Reserve, northeastern Chiapas state. We identified 15 testate amoebae taxa distributed across seven genera. Eleven were identified to species level and four to strain (infra-subspecific level), and taxa were distributed unevenly among samples. Distribution of taxa in samples was related to dissolved oxygen (DO) concentration in the water measured near the sediment surface. Arcella discoides and Centropyxis aculeata strain “aculeata” were the most tolerant of low oxygen concentrations, whereas the other taxa require higher DO levels. The influence of oxygen was also seen at the assemblage level. Sites with low DO concentrations had Shannon Diversity Index (SDI) values <1.5, an indication of stressful ambient conditions. We identified two species assemblage types, which are distinguished by their oxygen concentration requirements. Assemblage 1 was more diverse and possessed species that are intolerant of low oxygen concentrations, whereas Assemblage 2 possessed fewer, rarer, opportunistic species that tolerate stressful conditions. Low oxygen concentrations are related to water depth and the combination of these two variables is important in determining the composition of testate amoebae assemblages in Lacandón Forest lakes. Quantitative relationships between testate amoebae assemblages and water depth will enable use of sedimented amoebae remains for paleolimnological inference of past water level changes in lakes of the Lacandón Forest.

Effect of Dissolved Oxygen Concentrations on the Toxicity of Several Poisons to Rainbow Trout (Salmo Gairdnerii Richardson)

1961 ◽  
Vol 38 (2) ◽  
pp. 447-455
Author(s):  
R. LLOYD
Keyword(s):  
Rainbow Trout ◽  
Dissolved Oxygen ◽  
Oxygen Concentration ◽  
Ph Value ◽  
Dissolved Oxygen Concentration ◽  
Low Oxygen ◽  
Copper Salts ◽  
Respiratory Flow ◽  
The Difference ◽  
Oxygen Concentrations

1. A given reduction in the dissolved oxygen concentration of the water from the air-saturation value to a lower level increases the toxicity to rainbow trout of zinc, lead and copper salts, and of a mixture of monohydric phenols, to about the same extent. 2. The effect of a reduced oxygen concentration on the toxicity of ammonia solutions is greater than that found for the other four poisons; the extra increase can be accounted for by a theoretical calculation of the difference between the pH value of the bulk of the solution and that at the gill surface. 3. An hypothesis is presented to account for the effect of low oxygen concentrations on the toxicity of poisons to fish. It assumes that a given toxic effect is produced by a specified concentration of poison at the gill surface, and suggests that this concentration is governed not only by the concentration of poison in the bulk of the solution but also by the velocity of respiratory flow.

Effect of Physicochemical Variables on Algal Autoflotation

1992 ◽  
Vol 26 (7-8) ◽  
pp. 1769-1778 ◽  
Author(s):  
S.-I. Lee ◽  
B. Koopman ◽  
E. P. Lincoln
Keyword(s):  
Dissolved Oxygen ◽  
Oxygen Concentration ◽  
Retention Time ◽  
Contact Time ◽  
Pilot Scale ◽  
Dissolved Oxygen Concentration ◽  
Physicochemical Variables ◽  
Rise Rate ◽  
Mixing Intensity ◽  
Maximum Rise

Combined chemical flocculation and autoflotation were examined using pilot scale process with chitosan and alum as flocculants. Positive correlation was observed between dissolved oxygen concentration and rise rate. Rise rate depended entirely on the autoflotation parameters: mixing intensity, retention time, and flocculant contact time. Also, rise rate was influenced by the type of flocculant used. The maximum rise rate with alum was observed to be 70 m/h, whereas that with chitosan was approximately 420 m/h. The efficiency of the flocculation-autoflotation process was superior to that of the flocculation-sedimentation process.

Effect of low oxygen concentration on activation of inflammation by Helicobacter pylori

2021 ◽  
Vol 560 ◽  
pp. 179-185
Author(s):  
Adiza Abass ◽  
Tokuju Okano ◽  
Kotchakorn Boonyaleka ◽  
Ryo Kinoshita-Daitoku ◽  
Shoji Yamaoka ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Oxygen Concentration ◽  
Low Oxygen ◽  
Low Oxygen Concentration
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