Coordination of Respiratory and Hydrostatic Functions of the Swimbladder in the Central Mudminnow, Umbra Limi

1981 ◽  
Vol 92 (1) ◽  
pp. 37-52
Author(s):  
JOHN H. GEE
Keyword(s):  
Water Surface ◽  
Energy Costs ◽  
O2 Uptake ◽  
Neutral Buoyancy ◽  
Air Breathing ◽  
Limited Ability ◽  
Hypoxic Conditions ◽  
Water Fish ◽  
Hypoxic Water ◽  
Dissolved O2

1. Observations of behaviour and changes in buoyancy of Umbra limi, a facultative air-breathing fish, were studied to understand coordination of respiratory and hydrostatic functions of the swimbladder. 2. Fish were exposed to either normoxic or hypoxic water in either undisturbed or disturbed (simulating predator presence) conditions. Declines in swimbladder volume occurred between air-breaths as O2 was removed. These varied between treatments averaging 1.3% in disturbed normoxic conditions, 4.1% and 6.4% in undisturbed treatments (normoxic and hypoxic conditions respectively), and 8.3% in disturbed hypoxic conditions. 3. To minimize the extent and rate of such changes and thereby reduce energy costs of a non-optimal buoyancy, fish either maintained a continuous positive buoyancy at the water surface, compressed the swimbladder gases after inspiration and gradually reduced the pressure to compensate for O2 uptake, or increased their reliance on aquatic O2. The use of any of the above mechanisms was determined by the amount of dissolved O2 and presence or absence of disturbance. 4. In normoxic water fish without access to the surface maintained neutral buoyancy despite a very limited ability to secrete swimbladder gases. 5. The frequency of air-breathing in normoxic water was independent of swimbladder O2 levels, indicating that fish breathe air in normoxic water in response to a decline in swimbladder volume. 6. The potentially conflicting roles of the swimbladder are well co-ordinated.

Respiratory patterns and antipredator responses in the central mudminnow, Umbra limi, a continuous, facultative, air-breathing fish

1980 ◽  
Vol 58 (5) ◽  
pp. 819-827 ◽  
Author(s):  
John H. Gee
Keyword(s):  
Air Breathing ◽  
Aerial Respiration ◽  
Resistance To Hypoxia ◽  
Antipredator Responses ◽  
Water Fish ◽  
Progressive Hypoxia ◽  
Hypoxic Water ◽  
High Level ◽  
Random Times ◽  
Frequency Of Respiration

The central mudminnow. Umbra limi, is a continuous facultative air breather whose respiration is primarily aquatic in normoxic water and primarily aerial in hypoxic water. Under these conditions the frequency of respiration (air breaths; branchial breaths) by the primary mode increases with temperature. In hypoxic water, fish exposed to simulated predator disturbance breathed air in synchrony where a breath by one fish was immediately followed by breaths from one or more other fish. Undisturbed fish breathed air at random times with respect to other individuals. The level of dissolved O2 at which fish switch from primarily aquatic to primarily aerial respiration during progressive hypoxia was positively related to temperature. When fish were exposed to progressive hypoxia in groups (n = 10) the transition to air breathing in terms of dissolved O2 concentration was unaffected by acclimation to hypoxia and by simulated predator disturbance. When held alone (isolated) and disturbed, fish became very active and switched to aerial respiration at a higher level of dissolved O2 than either fish held alone and undisturbed or fish held in a group of 10. During progressive hypoxia without access to air, mudminnows maintained both a high level or activity and frequency of branchial breathing down to 15 Torr (1 Torr = 133.322 Pa). Acclimation to hypoxia did not greatly increase resistance to hypoxia in fish without access to air.

scholarly journals Respiratory and hydrostatic functions of the intestine of the catfishes Hoplosternum thoracatum and Brochis splendens (Callichthyidae)

1978 ◽  
Vol 74 (1) ◽  
pp. 1-16 ◽  
Author(s):  
J. H. Gee ◽  
J. B. Graham
Keyword(s):  
Gas Phase ◽  
Respiratory Organ ◽  
Neutral Buoyancy ◽  
Similar Frequency ◽  
Air Breathing ◽  
Aquatic Respiration ◽  
Metabolic Scope ◽  
Hypoxic Water ◽  
The Mean ◽  
Increased Activity

1. The air-breathing behaviour of Hoplosternum thoracatum and Brochis splendens has been studied and their strategy of coordinating the respiratory and hydrostatic functions of the accessory respiratory organ has been examined. 2. H. thoracatum and B. splendens are continuous but not obligate air-breathers and individuals of the former breathe air in synchrony with each other. 3. Frequency of air-breathing increased with increased activity in H. thoracatum. 4. Aquatic respiration (Vo2) in H. thoracatum decreased in hypoxic water but aerial Vo2 maintained a fairly constant total Vo2 independent of aquatic O2. Total Vo2 is higher when fish breathe both air and water but aerial Vo2 did not exceed 75% of total Vo2. 5. The accessory respiratory organ provides about 75% of the lift required to attain neutral buoyancy whereas the swimbladder provides less than 5%. The mean decreases in volume of the accessory respiratory organ in the period between breaths of B. splendens and H. thoracatum were 13.2 and 7.8% respectively. 6. With a gas phase of O2, B. splendens maintained a similar frequency of air breathing and showed a slightly greater reduction in buoyancy between air breaths when compared to breathing air. With a gas phase of N2, air breathing was less frequent and decreases in buoyancy between air breaths were much less than when breathing air. 7. The respiratory and hydrostatic functions of the accessory respiratory organ are compatible. Buoyancy is maintained by frequent air breaths taken in part in response to a decrease in volume of the accessory respiratory organ. This reservoir of O2 could increase metabolic scope during bursts of activity.

scholarly journals Maximal exercise at extreme altitudes on Mount Everest

1983 ◽  
Vol 55 (3) ◽  
pp. 688-698 ◽  
Author(s):  
J. B. West ◽  
S. J. Boyer ◽  
D. J. Graber ◽  
P. H. Hackett ◽  
K. H. Maret ◽  
...  
Keyword(s):  
Partial Pressure ◽  
Maximal Exercise ◽  
Ambient Air ◽  
O2 Uptake ◽  
Mount Everest ◽  
Air Breathing ◽  
Co2 Partial Pressure ◽  
O2 Partial Pressure ◽  
Low Levels ◽  
Arterial Po2

Maximal exercise at extreme altitudes was studied during the course of the American Medical Research Expedition to Everest. Measurements were carried out at sea level [inspired O2 partial pressure (PO2) 147 Torr], 6,300 m during air breathing (inspired PO2 64 Torr), 6,300 m during 16% O2 breathing (inspired PO2 49 Torr), and 6,300 m during 14% O2 breathing (inspired PO2 43 Torr). The last PO2 is equivalent to that on the summit of Mt. Everest. All the 6,300 m studies were carried out in a warm well-equipped laboratory on well-acclimatized subjects. Maximal O2 uptake fell dramatically as the inspired PO2 was reduced to very low levels. However, two subjects were able to reach an O2 uptake of 1 l/min at the lowest inspired PO2. Arterial O2 saturations fell markedly and alveolar-arterial PO2 differences increased as the work rate was raised at high altitude, indicating diffusion limitation of O2 transfer. Maximal exercise ventilations exceeded 200 l/min at 6,300 m during air breathing but fell considerably at the lowest values of inspired PO2. Alveolar CO2 partial pressure was reduced to 7-8 Torr in one subject at the lowest inspired PO2, and the same value was obtained from alveolar gas samples taken by him at rest on the summit. The results help to explain how man can reach the highest point on earth while breathing ambient air.

Using an acoustic telemetry array to assess fish volumetric space use: a case study on impoundments, hypoxia and an air-breathing species (Neoceratodus forsteri)

2017 ◽  
Vol 68 (8) ◽  
pp. 1532 ◽  
Author(s):  
D. T. Roberts ◽  
V. Udyawer ◽  
C. Franklin ◽  
R. G. Dwyer ◽  
H. A. Campbell
Keyword(s):  
Atmospheric Oxygen ◽  
Habitat Preferences ◽  
Three Dimensional ◽  
Depth Sensor ◽  
Experimental Conditions ◽  
Air Breathing ◽  
Hypoxic Conditions ◽  
Hypoxic Zone ◽  
Increasing Demand ◽  
Oxygen Requirements

Facultative air-breathing fish can persist in hypoxic waters due to their capacity to acquire atmospheric oxygen. Most studies examining responses of air-breathing fish to aquatic hypoxia have occurred under experimental conditions. How air-breathing fish respond to hypoxic conditions in the field has received less attention. Using depth sensor transmitters and an array of acoustic receivers to monitor the facultative air-breathing Australian lungfish (Neoceratodus forsteri), we investigated habitat preferences and behavioural responses to seasonal hypoxic zones in a riverine impoundment. Three-dimensional (3-D) kernel utilisation distribution (KUD) models revealed that during stratified conditions, lungfish remained above the oxycline, rarely venturing into hypoxic waters, whereas during holomixis lungfish used a wider range of depths. Total volumetric space utilisation did not change significantly during stratified periods, but the distribution of space used changed, constrained by the oxycline. Despite N. forsteri having lungs to supplement oxygen requirements, the presence of a hypoxic zone constrained the core (50% 3-D-KUD) volumetric space used by lungfish to <1.6% of the total available space of the study area. With increasing demand for new impoundments in many tropical and subtropical regions, the present study provides insights to how air-breathing fish species may respond to altered riverine conditions from impoundments.

Selective control of branchial arch perfusion in an air-breathing Amazonian fish Hoplerythrinus unitaeniatus

1978 ◽  
Vol 56 (4) ◽  
pp. 959-964 ◽  
Author(s):  
D. G. Smith ◽  
B. J. Gannon
Keyword(s):  
Branchial Arch ◽  
Dorsal Aorta ◽  
Oxygen Loss ◽  
Air Breathing ◽  
Gas Bladder ◽  
Hypoxic Water ◽  
Major Branch ◽  
Β Adrenergic Receptors ◽  
Hoplerythrinus Unitaeniatus

Vascular responses to adrenergic and cholinergic agonists were investigated in the air-breathing teleost Hoplerythrinus unitaeniatus during in situ saline perfusion of the ventral aorta.The vasculature resembled that of other teleosts in having inhibitory β-adrenergic receptors and excitatory muscarinic receptors, probably located in the gills. The gas bladder vessels were apparently devoid of adrenergic and cholinergic receptors.The dorsal aorta was specialized between gill arches 2 and 3 in such a way that the dorsal aorta probably received most of its blood supply from arches 1 and 2. Arches 3 and 4 supplied the large coeliac artery whose major branch was to the gas bladder. Acetylcholine reduced the number of perfused gill arches so that most of the ventral aortic flow was directed towards the gas bladder through arches 3 and 4. This was seen as a possible solution to the problem of transbranchial oxygen loss that could arise if blood oxygenated at the gas bladder was exposed to hypoxic water at the gills.

The partitioning of oxygen uptake from air and from water by the large obligate air-breathing teleost pirarucu (Arapaima gigas)

1978 ◽  
Vol 56 (4) ◽  
pp. 974-976 ◽  
Author(s):  
E. Don Stevens ◽  
George F. Holeton
Keyword(s):  
Oxygen Uptake ◽  
Air Breathing ◽  
Anoxic Water ◽  
Arapaima Gigas ◽  
Hypoxic Water

Pirarucu, weighing 2 to 3 kg, ventilated their gills 16 to 24 times per minute and ventilated their lungs every 1 to 2 min. Average oxygen uptake from water was 23 mg∙h−1∙kg−1; average oxygen uptake from air was 80 mg∙h−1∙kg−1. That is, in normoxic water they obtain about 75% of their oxygen from air, and never less than 50% from air. In hypoxic water the fraction from air increases, ultimately to 100% in anoxic water.

scholarly journals The Transition to Air Breathing in Fishes: III. Effects of Body Size and Aquatic Hypoxia on the Aerial Gas Exchange of the Swamp Eel Synbranchus Marmoratus

1984 ◽  
Vol 108 (1) ◽  
pp. 357-375 ◽  
Author(s):  
JEFFREY B. GRAHAM ◽  
TROY A. BAIRD
Keyword(s):  
South American ◽  
Air Breathing ◽  
Aquatic Respiration ◽  
Environmental Selection ◽  
Blood Haemoglobin ◽  
Hypoxic Water ◽  
Breath Co2 ◽  
Hb Concentration ◽  
Swamp Eel ◽  
Exchange Surface

Synbranchus marmoratus (Bloch) breathes air during terrestrial excursions and while dwelling in hypoxic water and utilizes its gills and adjacent buccopharyngeal epithelium as an air-breathing organ (ABO). This fish uses gills and skin for aquatic respiration in normoxic (air-saturated) water but when exposed to progressive aquatic hypoxia it becomes a metabolic O2 conformer until facultative air breathing is initiated. The threshold PwOO2 (aquatic O2 tension or partial pressure in mmHg) that elicits air breathing in S. marmoratus is higher in larger fish. However, neither air-breathing threshold nor the blood haemoglobin (Hb) concentration of this species were changed following hypoxia (PwOO2 &lt; 20 mmHg) acclimation. In hypoxic water S. marmoratus supplies all of its metabolic O2 requirement through air breathing. ABO volume scales with body weight raised to the power of 0.737 and the amount of O2 that is removed from each air breath depends upon the length of time it is held in the ABO. Ambient PwOO2 directly affects the air-breath duration of this fish, but the effect is smaller than in other species. Also, average air-breath duration (15.7 min at PwOO2 0–20 mmHg) and the average inter-air-breath interval (15.1 min) of S. marmoratus are both longer than those of other air-breathing fishes. Although the gills of S. marmoratus are involved in aerial O2 uptake, expelled air-breath CO2 levels are not high and always closely correspond to ambient PwCOCO2, indicating that virtually no respiratory CO2 is released to air by this fish. CO2 extrusion therefore must occur aquatically either continuously across another exchange surface or intermittently across the gills during intervals between air breaths. This study with S. marmoratus from Panama reveals physiological differences between this population and populations in South America. The greater Hb content of South American S. marmoratus may be the result of different environmental selection pressures.

Acetazolamide alters temperature regulation during submaximal exercise

1990 ◽  
Vol 69 (4) ◽  
pp. 1402-1407 ◽  
Author(s):  
W. F. Brechue ◽  
J. M. Stager
Keyword(s):  
Stroke Volume ◽  
Minute Ventilation ◽  
Exercise Bout ◽  
Cycle Ergometer ◽  
Submaximal Exercise ◽  
Whole Body ◽  
Co2 Removal ◽  
O2 Uptake ◽  
Double Blind ◽  
Hypoxic Conditions

Acetazolamide (ACZ), a potent carbonic anhydrase inhibitor, is known to decrease submaximal exercise tolerance under normoxic and hypoxic conditions. These decrements in performance occur despite the maintenance of O2 consumption and CO2 removal. Because ACZ is a diuretic, it induces a moderate hypohydration that may have a role in reducing the ability to sustain exercise through cardiovascular and thermoregulatory impairment. To investigate this potential impairment, seven healthy males between 21 and 35 yr of age were studied in a double-blind crossover design (placebo vs. ACZ). ACZ was administered in three 250-mg oral doses 14, 8, and 2 h before exercise. Subjects exercised at 70% peak O2 uptake for 30 min on a cycle ergometer in a normoxic thermoneutral environment (25 degrees C, 40% relative humidity). Results indicate that exercise minute ventilation was greater but O2 uptake, CO2 output, and respiratory exchange ratio did not differ with ACZ. ACZ led to lower mean skin (0.7 degrees C), higher rectal (0.6 degrees C), and higher mean body temperatures (0.4 degrees C) after 30 min of exercise. Whole-body sweat loss was reduced 23%, and heat storage during the exercise bout was increased 55%. Stroke volume decreased 25%, and arteriovenous O2 difference increased 15%. A significant inverse relationship (r = -0.63) between heart rate and stroke volume was observed. It is concluded that previously reported decreases in the ability to sustain submaximal exercise with ACZ may be related to hypohydration-induced impairment of the cardiovascular and thermoregulatory systems.

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