OXYGEN CONSUMPTION, BRAIN METABOLISM AND RESPIRATORY MOVEMENTS OF GOLDFISH DURING TEMPERATURE ACCLIMATIZATION, WITH SPECIAL REFERENCE TO LOWERED TEMPERATURES

¹ Biology Department, Newcomb College of Tulane University, New Orleans

1. Oxygen consumption of goldfish at acclimatization temperatures increases between 12° C. and 27° C. but is again lower at 37.8° C.

2. When measured at a single temperature, there is an inverse relation between oxygen consumption of brain breis and the acclimatization temperature of fish between 12° and 37.5° C. The level of oxygen consumption of muscle breis, however, does not differ significantly for fish acclimatized at 12° and 27° C.

3. When measured over the range from 0° to 37.8° C., the metabolism of fish brain tissue increases rapidly between 0° and 27°, but at higher temperatures the increase with temperature is less marked and at the highest temperature may be lower again.

4. At temperatures up to 27° C., logarithmic plots of the metabolism of brain tissue and of whole animal respiration are similar in slope.

5. Between 4° and 27° C., the rate of opercular movements at the acclimatization temperatures increases with temperature just as does the rate of brain tissue metabolism calculated for the acclimatization temperatures, the ratios of the two being the same at 12°, 20° and 27° C. Above 27° C., however, the rate of the respiratory rhythm does not rise significantly.

6. The rates at which oxygen consumption of the fish, the opercular rhythm and the brain metabolism change during acclimatization to 12° C. after previous acclimatization at 27° C. are the same, approximately 50 per cent of the change taking place in two days. This and other observations are interpreted as indicating that the changes in brain metabolism observed to accompany low temperature acclimatization constitute a homeostatic mechanism making possible the maintenance of more normal functioning than would otherwise be possible at the new low temperature.

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