EFFECTS OF SUPERABUNDANT OXYGEN ON THERMAL TOLERANCE OF GOLDFISH

A hypothesis may be made out that the respiratory/circulatory, and possibly the oxygen transport, systems are importantly involved in thermal death of goldfish. Experiments showed that at two distinct levels of temperature acclimation, superabundant oxygen in the water could produce a definite improvement either in time of survival at a fixed lethal temperature or in lethal temperature reached as a result of heating. Despite this positive effect of high oxygen a clear cut failure of oxygen, in excess of about 5 atmospheres (partial pressure), to produce further improvement in thermal tolerance suggests the failure of some critical system directly affected by temperature. The experiments, while revealing nothing of the detailed mechanisms involved, certainly do not invalidate the hypothesis proposed, and open a way to further investigation.