The respiratory behaviour of an air-breathing catfish, Clarias macrocephalus (Clariidae)

1987 ◽  
Vol 65 (2) ◽  
pp. 348-353 ◽  
Author(s):  
David J. Bevan ◽  
Donald L. Kramer
Keyword(s):  
Dissolved Oxygen ◽  
Atmospheric Oxygen ◽  
Breathing Frequency ◽  
Dissolved Oxygen Concentration ◽  
Significant Cost ◽  
Air Breathing ◽  
Aerial Respiration ◽  
Travel Costs ◽  
Clarias Macrocephalus ◽  
Do So

Clarias macrocephalus are continuous, facultative air breathers. Individuals (7.6–20.9 g) survived more than 25 days in normoxic water without surface access. Buoyancy decreased and water-breathing frequency increased when surface access was denied, but growth rate and the frequency of air-breathing attempts did not change. We examined air-breathing and water-breathing frequency in shallow (60 cm) and deep (235 cm) water under normoxic (8.0 mg O2∙L−1) and hypoxic (0.3, 0.7, 1.2, and 2.0 mg O2∙L−1) conditions to examine how changes in the travel costs of breathing affected the use of each respiratory mode. Air-breathing and water-breathing frequency increased as dissolved oxygen decreased from 8.0 to 2.0 mg O2∙L−1. Below this level air breathing continued to increase, but water breathing dropped sharply. At higher levels of dissolved oxygen (8.0 and 2.0 mg O2∙L−1), fish in deep water had lower air-breathing and higher water-breathing frequencies than fish in shallow water. Vertical distance travelled and time spent in air breathing increased with increasing depth and with decreasing level of dissolved oxygen. These results support the hypotheses that travel is a significant cost of aerial respiration and that fish respond to increases in this cost by decreasing their use of atmospheric oxygen when dissolved oxygen concentration permits them to do so.

Thermal Ageing of Some Insulating Fluids in Contact with Insulation Paper and Copper

2018 ◽  
Vol 68 (12) ◽  
pp. 2881-2885
Author(s):  
Iosif Lingvay ◽  
Gabriela Oprina ◽  
Livia Carmen Ungureanu ◽  
Alexandra Pica ◽  
Valerica Stanoi
Keyword(s):  
Experimental Data ◽  
Dissolved Oxygen ◽  
Copper Foil ◽  
Atmospheric Oxygen ◽  
Thermal Ageing ◽  
Dissolved Oxygen Concentration ◽  
Mineral Oils ◽  
Synthetic Ester ◽  
Cu2o Film ◽  
Transformer Oils

The behaviour of copper and insulation paper in various electrical insulating fluids (transformer oils) exposed to thermal ageing at 110�30C for 1000 hours in closed vessels (without access to atmospheric oxygen) has been studied. The processing of the comparative experimental data revealed in all cases that the concentration of dissolved oxygen in the investigated oils decreases exponentially during the heat treatment. In the presence of the copper foil, the oxygen is almost depleted (the dissolved oxygen concentration is approaching zero), indicating a higher affinity of the copper to oxygen than the affinity to oxygen of the investigated oils. In the presence of the copper foil and / or of the insulation paper, the degradation processes of the mineral oils have a pronounced character, explained by the catalytic activity of the Cu2O film that has been formed and by the paper degradation, respectively. A high thermo-oxidative stability was noticed in the case of natural triglyceride oils, particularly for the synthetic ester-based oil.

Aerial respiration in the catfish, Corydoras aeneus (Callichthyidae)

1980 ◽  
Vol 58 (11) ◽  
pp. 1984-1991 ◽  
Author(s):  
Donald L. Kramer ◽  
Martha McClure
Keyword(s):  
Dissolved Oxygen ◽  
Air Breathing ◽  
Aerial Respiration ◽  
Posterior Intestine ◽  
Partial Pressures

Corydoras aeneus uses the posterior intestine for aerial respiration. Ventilation takes place in a rapid dash to the surface. Air is inspired during the 0.06–0.07 s that the mouth is exposed; expiration occurs via the anus as the fish begins to dive. Air breathing occurs at all dissolved oxygen partial pressures [Formula: see text] from 0 Torr (1 Torr = 133.322 Pa) to at least 140 Torr, but frequency, ranging from 1–45 breaths∙h−1, is negatively correlated with [Formula: see text]. Corydoras aeneus survive at least 9 days without air breathing under normoxic conditions [Formula: see text] but below 15 Torr, only fish able to reach the surface survive. Air-breathing rates are significantly influenced by variations in depth between 10–120 cm but the pattern of response depends on [Formula: see text] and involves changes in activity.

Short-term effects of food availability on air-breathing frequency in the fish Corydoras aeneus (Callichthyidae)

1983 ◽  
Vol 61 (9) ◽  
pp. 1964-1967 ◽  
Author(s):  
Donald L. Kramer ◽  
E. Anne Braun
Keyword(s):  
Dissolved Oxygen ◽  
Oxygen Demand ◽  
Ecological Factors ◽  
Food Presentation ◽  
Breathing Frequency ◽  
Ambient Conditions ◽  
Breathing Patterns ◽  
Dissolved Oxygen Tension ◽  
Air Breathing ◽  
Before And After

To examine the hypothesis that breathing patterns in fish capable of bimodal respiration can be modified by ecological factors that alter the relative costs of air and water breathing, we determined the air-breathing frequency and activity of a group of Corydoras aeneus before and after presentation of small amounts of food. In nature a reduction in air breathing while feeding on small, patchy resources should reduce loss of food to competitors and lower the risk of failing to relocalize the food source. Activity always increased after food presentation, but the change in air breathing depended on dissolved oxygen tension. Air breathing decreased after food presentation at 116 and 72 torr (1 torr = 133.322 Pa), stayed the same at 44 torr, and increased at 24 torr. This suggests that although oxygen demand increases during feeding, air breathing is decreased when the ambient conditions permit a compensatory increase in the uptake of dissolved oxygen.

scholarly journals Aquatic and Aerial Respiration Rates, Muscle Capillary Supply and Mitochondrial Volume Density in the Airbreathing Catfish (Clarias Mossambigus) Acclimated to Either Aerated or Hypoxic Water

1983 ◽  
Vol 105 (1) ◽  
pp. 317-338 ◽  
Author(s):  
IAN A. JOHNSTON ◽  
LYNNE M. BERNARD ◽  
GEOFFREY M. MALOIY
Keyword(s):  
Respiration Rate ◽  
Fibre Volume ◽  
Acute Exposure ◽  
Routine Activity ◽  
Breathing Frequency ◽  
Air Breathing ◽  
Aerial Respiration ◽  
Capillary Supply ◽  
Mitochondrial Volume ◽  
Hypoxia Acclimation

Specimens of the African air-breathing catfish Clarias mossambicus were acclimated to either aerated (PwO2 15.3 KPa) or hypoxic (PwO2 2.4KPa) water for up to 27 days at 20 °C. Routine respiration rate for fish acclimated to aerated water was 85.7 mlO2 (kgbodyweight)−1 h−1. Gas exchange across the suprabranchial chambers accounted for 25% of the total. In aerated water the interval between air-breaths varied from 1.4 to 30.6 min. On acute exposure to hypoxia air-breathing frequency was unaltered (6.3 h−1) although aerial respiration rate increased by 70%. This suggests that ventilation of the suprabranchial chambers is variable and that air-breathing frequency is a poor measure of air-breathing effort. Total respiration decreased by 46% on acute exposure to hypoxia (PwO2 2.4 KPa), reflecting a reduction in routine activity. Following acclimation to hypoxia, airbreathing frequency (8.1 h−1) was higher and total routine respiration rate increased from 46.3 to 67.8 mlO2 kg−1h−1. The increased oxygen consumption with hypoxia acclimation was largely the result of an increase in aquatic respiration from 10.4 to 27.5 mlO2kg−1h−1 Measurements were made of mitochondrial volume densities [Vv(mt,f)] and capillary supply to fast and slow myotomal muscles. The fraction of fibre volume occupied by mitochondria was 15 percnt; for slow and 2.5% for fast muscles. Values for [Vv(mt,f)] obtained for fish slow fibres are much higher than for homologous muscles in birds and mammals and show a good correlation with capillary density [NA(c,f)]. Hypoxia acclimation did not result in changes in either muscle Vv(mt,f) or NA(c,f). It is suggested that increased ventilation of the suprabranchial chambers and greater oxygen extraction across the gills obviates the need for modifications in these parameters.

The effect of swimming depth on respiratory behavior of the honey gourami, Colisa chuna (Pisces, Belontiidae)

1986 ◽  
Vol 64 (9) ◽  
pp. 1893-1896 ◽  
Author(s):  
David J. Bevan ◽  
Donald L. Kramer
Keyword(s):  
Gas Exchange ◽  
Significant Cost ◽  
Air Breathing ◽  
Adaptive Changes ◽  
Travel Costs ◽  
Feeding Sites ◽  
Swimming Depth ◽  
Respiratory Behavior

We tested the hypothesis that fish capable of bimodal respiration would respond to the increased travel costs of surfacing by decreasing their frequency of air breathing. Honey gouramis were permitted to move freely in a 220 cm deep aquarium, but their preferred depths were manipulated by changing the location of shelter and feeding sites. With increased depth the interval between air breaths increased. This supports the argument that travel to and from the surface is a significant cost for air-breathing fish. It provides evidence that respiratory behavior can be affected by factors not directly involved in the physiology of gas exchange. Furthermore, it suggests that retention of water-breathing capacity in air-breathing species may reduce the costs of breathing through adaptive changes in partitioning.

Mass Appearance of Cyanobacterium Planktothrix rubescens in Lake Piaseczno, Poland

2003 ◽  
Vol 38 (1) ◽  
pp. 141-152 ◽  
Author(s):  
Danuta Krupa ◽  
Krzysztof Czernaś
Keyword(s):  
Dissolved Oxygen ◽  
Primary Production ◽  
Catchment Area ◽  
High Water ◽  
Water Bloom ◽  
High Water Temperature ◽  
Dissolved Oxygen Concentration ◽  
Planktothrix Rubescens ◽  
Assimilation Number ◽  
Bottom Zone

Abstract In 1989, Lake Piaseczno, Poland, exhibited a mass appearance of Planktothrix rubescens. During this time the pelagic and littoral areas exhibited significant increases in areal primary production (400 and 41 mg C m-2 h-1, respectively), chlorophyll α (100 and 6.9 mg m-2, respectively) and assimilation number (4 and 5.9 mg C m-2 h-1/mg chlα m-2, respectively). After the water bloom subsided, a reduction of dissolved oxygen concentration (down to 1.5 mg L-1) and high water temperature (10.2°C) in the offshore bottom zone was observed. While from 1991 to 1996, the primary production, chlorophyll α concentration and assimilation number values were decreasing, they were significantly higher than the values reported in 1986, prior to the mass cyanobacteria appearance. An indirect correlation with ion levels indicated that the outbreak of the cyanobacteria was linked with inflow of nutrients from the catchment area. The dramatic changes in the range and variability of the phytoplankton density indicate that the recent eutrophication of the lake has had profound effects on the structure and productivity of the aquatic community.

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.

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