New Zealand Journal of Marine and Freshwater Research abstracts

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Oxygen consumption and apnoea in the shortfin eel, Anguilla australis schmidtii

Malcolm E. Forster

Department of Zoology, University of Canterbury, Christchurch 1, New Zealand

Abstract Patterns of ventilation, oxygen consumption (VO₂),iblood gas tensions (PaO₂ and PaCO₂) and pH were determined in shortfin eels (Anguilla australis schmidtii (Phillips)). At rest, shortfin eels (average weight 646.5 ± 64.5 g) had a VO₂ of 20.4 ± 1.2 ml. kg-'.h"¹ (n = 13) at 17.5 ± 0.2 °c, with smaller fish having the highest metabolic rates. The frequency of ventilation was inversely proportional to body weight in both A. australis schmidtii and A. dieffenbachii. In air-saturated water 10 eels exhibited periodic apnoea (mean duration 3.59 min); periods of ventilation were more variable in duration (mean 4.92 min). After 2.62 min of apnoea, the PaO₂ of dorsal aortic blood had fallen from 9.12 to 1.91 kPa. Thus, although the blood has a high affinity for oxygen and the haemoglobins are 30% oxygen-saturated at this low PaO₂, the eel allows its blood to be significantly depleted in oxygen during apnoeic pauses at rest. When ventilating its gills at rest, PaO₂ does not approach the PO₂ of the inspired water. It is suggested that these features of respiration in eels result in a saving of metabolic costs involved in ventilation. The results are discussed in terms of the eel's ability to withstand hypoxic conditions.

Keywords Anguilla spp.; oxygen consumption; gill ventilation; (apnoea); blood gases; haematocrit.

New Zealand Journal of Marine & Freshwater Research, 1981, 15(1): 85-90
Received 11 August 1980; revision received 6 October 1980

PDF file of entire paper: medium quality (481K); (scanned from paper original: notes about this process)

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