Aspects of the respiratory physiology of the burrowing fish Cepola rubescens L.

Abstract

1. 1. The burrowing fish Cepola rubescens L. spends long periods concealed in oxygen deficient burrows: field measurements for the P O 2 at the burrow aperture and within the burrow were 101.8 (6.3) and 83.0 (5.2) mm of Hg; means (standard errors). 2. 2. Contunuous measurement of burrow water P O 2 using captive fish showed that body movements within the burrow cause water displacements of the order of 10 ml which can increase the P O 2 with increments ranging from 4.4 to 44.0%. 3. 3. Fish removed from burrows and acclimatized to a closed respirometer achieved near stabilization of oxygen consumption over a wide range of ambient P O 2 , with a critical P O 2 between 50 and 70 mm of Hg. 4. 4. Haematological studies on fish of 23.2 to 57.8 cm standard length gave the following values; means (standard errors): haematocrit, 17.2 (1.05)%; haemoglobin, 0.20 (0.02) mm/tetramer ATP, 0.71 (0.15) mM/1; PaO 2, 10.90 (2.15) mm of Hg; PvO 2, 6.04 (0.80) mm of Hg; CaO 2, 0.65 (0.09) vol.%; CvO 2, 0.34 (0.08) vol.%; pHa, 7.659 (0.05); pHv, 7.635 (0.03); carrying capacity, 3.24 (0.22) vol.%. 5. 5. The respiratory properties of the blood indicate adaptations to survival in oxygen deficient burrows.