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 < 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.

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.

Reduced blood O2 affinity associated with air breathing in osteoglossid fishes

1978 ◽  
Vol 56 (4) ◽  
pp. 891-897 ◽  
Author(s):  
K. Johansen ◽  
C. P. Mangum ◽  
R. E. Weber
Keyword(s):  
Striking Difference ◽  
Red Cell ◽  
Closely Related Species ◽  
Air Breathing ◽  
Arapaima Gigas ◽  
Uptake Rates ◽  
Hypoxic Water ◽  
The Difference ◽  
Hb Concentration ◽  
Freshwater Teleosts

Respiratory properties of blood in two closely related species of tropical freshwater teleosts, the osteoglossids Arapaima gigas, an obligatory air breather, and Osteoglossum bieirrhosum, an exclusive water breather, have been compared. Additionally, the O2 uptake rates (VO2) and breathing responses to hypoxic water were compared.The two species had similar values of hematocrit, hemoglobin (Hb) concentration, and O2, capacity, these being 28%, 7.5 g/100 ml, and 11.0 ml/100 ml for Osteoglossum and 30.8%, 7.5 g/100 ml, and 10.4 ml/100 ml for Arapaima. Red cell ATP and GTP levels were also similar in both species.A striking difference existed in the O2 affinity of red cell suspensions with a P50 value of 6.1 mmHg (1 mmHg = 133.322 Pa) at pH 7.4 (28 °C) for Osteoglossum against 21.0 mmHg for Arapaima. The difference persisted after purification and stripping of the hemoglobins of their red cell cofactors. We conclude that the O2-binding properties of the hemoglobin molecules in the two species are intrinsically different. The low O2 affinity in the air-breathing Arapaima permits O2 unloading at relatively high [Formula: see text]'s thus supporting a high [Formula: see text]. The high O2 affinity in Osteoglossum is necessary for Hb to function in O2 transport from a very hypoxic medium.

The Transition to Air Breathing in Fishes:: I. Environmental Effects on the Facultative Air Breathing of Ancistrus Chagresi and Hypostomus Plecostomus Loricariidae

1982 ◽  
Vol 96 (1) ◽  
pp. 53-67 ◽  
Author(s):  
JEFFREY B. GRAHAM ◽  
TROY A. BAIRD
Keyword(s):  
Fish Species ◽  
Environmental Effects ◽  
Breathing Rate ◽  
Breathing Frequency ◽  
Rate Reduction ◽  
Air Breathing ◽  
Aquatic Respiration ◽  
Saturated Water ◽  
Important Regulator ◽  
Hypoxia Acclimation

In response to progressive aquatic hypoxia, the armoured loricariid catfishes Ancistrus chagresi and Hypostomus plecostomus become facultative air-breathers and utilize their stomachs as accessory air-breathing organs. Hypostomus initiates air breathing at a higher aquatic O2 tension (Pw, Ow, O2) than does Ancistrus (60 v. 33 mmHg). Once begun, the air-breathing frequencies of both species increase with decreasing Pw, Ow, O2; the frequency of Ancistrus, however, is greater than and increases more with hypoxia than does that of Hypostomus, which appears to be a more efficient air breather. Hypoxia acclimation reduces the air-breathing rate of both species. A larger rate reduction occurs in Ancistrus, which, however, continues to require more frequent breaths than Hypostomus. Hypoxia acclimation does not affect the air-breathing threshold of either species, suggesting that external O2 receptors initiate facultative air breathing. In progressive aquatic hypercapnia Ancistrus has a lower air-breathing CO2 threshold (8.7 mmHg) than Hypostomus (12.8 mmHg). However, in some tests, individual fish of both species did not initiate air breathing even at Pw, COw, CO2 as high as 21 mmHg. Also, air breathing evoked by hypercapnia was short-lived; both species quickly compensated for this gas and resumed exclusively aquatic respiration within a few hours of exposure. Thus, CO2 is not an important regulator of air breathing in these species. Between 25 and 35 °C, the Pw, Ow, O2 air breathing threshold of Ancistrus is temperature-independent, but air-breathing frequency increases with temperature. Ancistrus and Hypostomus do not breathe air in normoxic (air-saturated) water; their air-breathing responses are evoked by environmental hypoxia. This is fundamentally different from other fish species that breathe air in normoxia in order to meet heightened metabolic demands. Also, the facultative air-breathing adaptations of Ancistrus and Hypostomus differ in scope and magnitude from those utilized by species that breathe air in nor-moxia and adapt to hypoxia by increasing air-breathing rate.

scholarly journals Acid–base regulation in the air-breathing swamp eel (Monopterus albus) at different temperatures

2018 ◽  
Vol 221 (10) ◽  
pp. jeb172551 ◽  
Author(s):  
Phan Vinh Thinh ◽  
Nguyen Thanh Phuong ◽  
Colin J. Brauner ◽  
Do Thi Thanh Huong ◽  
Andrew T. Wood ◽  
...  
Keyword(s):  
Acid Base ◽  
Air Breathing ◽  
Monopterus Albus ◽  
Different Temperatures ◽  
Swamp Eel

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.

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