Responses of the Respiratory Pumps to Hypoxia in the Rainbow Trout (Salmo Gairdnert)

Abstract

1. Unanaesthetized rainbow trout, when subjected to a lowered Po2 of the inspired water, show an increase in amplitude of pressures recorded from the buccal and opercular cavities. Pressure amplitudes were commonly found to be 0.5 cm of water in resting trout and increased 4- or 5-fold as inspired Po2 was reduced. Differential pressures across the gills also increased with hypoxia. 2. Typically the minute volume in a 400-600 g trout increased from about 0.2 to 0.6 l/kg/min when the inspired Po2 was lowered from 150 to 80 mm Hg, but rose to 1-5l/kg/min at lower Po2. Increased minute volumes are mainly due to increases in stroke volume; respiratory frequency remains fairly constant at Po2 's above about 8o mm Hg. 3. The relation between differential pressure and minute volume is fairly linear over much of the range, but minute volume increases more rapidly than differential pressure. 4. Oxygen consumption of the non-swimming fish increases during hypoxia and is related to the increased ventilation and differential pressure across the gills. 5. Estimates of the oxygen cost of breathing were made from the increased oxygen consumption during hyperventilation. Comparison of these estimates with estimates of the work done, using the pressure and volume measurements, gave figures for the overall efficiency of the pumping mechanism of about 10%.

Body size dictates physiological and behavioural responses to hypoxia and elevated water temperatures in Murray cod (Maccullochella peelii)

“…Consistent with other studies (e.g. Hughes and Saunders, 1970 ; Giacomin et al, 2019 ), we observed that fish significantly increased their GVR and the amplitude of opercular movements with increasing water temperature to increase oxygen supply to metabolizing tissues to delay the onset of anaerobic metabolism. Moreover, acute exposure of fish to warm water meant that fish engaged ASR earlier at higher oxygen saturation levels.…”

Coughing in the Rainbow Trout Salmo-Gairdneri and the Influence of Pollutants

“…In the past it has been common for assay of pollutants to be carried out using lethal or near lethal doses and while such methods have their value, it is equally important to know more of the sublethal effects of pollutants and how to assay them. The techniques developed in studies of fish respiratory physiology clearly have some value in this respect and the methods described here are relatively simple ones to which could be added ECG recording and the measurement of ventilation volume and oxygen consumption by similar methods (Hughes and Saunders, 1970). The particular parameter chosen here is of especial interest with respect to suspended solid pollutants but it may also be important in other cases.…”

Oxygen extraction efficiency of the tidally-ventilated rectal gills of dragonfly nymphs

“…As a result, the unidirectionally ventilated gills of water-breathing animals typically extract 70 to 85% of the O 2 from the inhaled water (e.g. [11][12][13][14]).…”