Respiration of the carp, Cyprinus carpio L., at 10 and 20° C and the effects of hypoxia

Abstract

Oxygen consumption of carp acclimated at 10 and 20° C has been measured under routine conditions. Some complications and precautions necessary in continuous flow respirometry are discussed. Routine Vo2 at different levels of hypoxia have been determined. Individual variation leads to scatter in the data and different methods of plotting the relationship between Vo2 and Po2 are proposed; attention is drawn to differences between inlet (or ambient) Po2 and inspired Po2. Using certain criteria a ‘critical’ oxygen tension of about 95 mm Hg was found at 20° C; Q10 values are about 2 at normoxia and some suggestions of an increase near to the critical oxygen tension were found. Blood samples from the dorsal aorta showed rising Pa,o2 of 16 mm Hg which increased to 70–80 mm Hg when Pinsp was 90 and they then fall as the inspired oxygen is lowered. During periods of deep hypoxia (25 mm Hg) blood lactate concentration increases steadily and indicates an increasing dependence on anaerobic mechanisms.