Behavioral and metabolic aspects of low temperature dormancy in the brown bullhead,Ictalurus nebulosus
- Cite this article as:
- Crawshaw, L.I., Lemons, D.E., Parmer, M. et al. Journal of Comparative Physiology B (1982) 148: 41. doi:10.1007/BF00688886
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Behavioral and physiological measurements were made during the winter at low temperatures to evaluate cold temperature dormancy in the brown bullhead.
At 17°C and when slowly cooled to 3°C the bullheads often buried themselves in the mud (Fig. 1). Animals buried at 3°C were not immobilized and would emerge from the mud following a disturbance.
No readjustment of the thermoregulatory mechanisms was seen when acclimatized bullheads were placed in a thermal gradient that was slowly cooled. At the end of 6–7 h, the bullheads always became quiescent in the warmest portion of the gradient available (11–13°C)-(Fig. 2).
Spontaneous activity and oxygen uptake were measured, at the acclimation temperature, for animals acclimated to 3–17°C at 2°C intervals.
Spontaneous activity in an annular tank showed a high degree of compensation between 5 and 17°C. At 3°C the bullheads showed much less spontaneous activity and an exceptionally low initial hyperactive period following placement in the tank (Fig. 3).
When oxygen uptake was measured with a closed system technique which involved a very slight disturbance, large increases in magnitude and variability of oxygen uptake occurred at higher acclimation temperatures. These large increases were not seen if oxygen uptake of sleeping fish was measured with an open system (Fig. 4).
Overwintering in this species may simply involve an increase in the time spent burrowed in the mud asleep.