Long-term cold acclimation leads to high Q(10) effects on oxygen consumption of loggerhead sea turtles caretta caretta

We monitored oxygen consumption ((V) over dotO(2)), body temperatures. (T-b), submersion intervals, and circadian rhythms of (V) over dotO(2) in nine loggerhead turtles during a 6-mo period. The turtles originated from the Tyrhennian Sea, South Italy (40degrees51'N, 14degrees17'E) and were kept in indoor tanks at constant photoperiod while being subject to the seasonal decline in water temperature (T-w = 27.1degrees to 15.3degreesC). From summer to winter, all turtles underwent profound reductions in (V) over dotO(2) (Q(10) = 5.4). Simulta neously, their activity was greatly reduced and submergence intervals increased. Over 24-h periods, however, the turtles showed no circadian rhythm in activity or. However, there. was a significant positive correlation between the proportion of a day spent actively swimming and (V) over dotO(2). T-b's were not sig nificantly different from Tw and followed the same seasonal decline. A second experiment was conducted to establish the effect of short-term exposure to various temperatures on.. T-b equilibrated with the experimental T-w within 3 h. The metabolic responses were again positively correlated with changes in T-w, but this time the corresponding Q(10) was only 1.3. On the basis of the range of body masses of the turtles used in this study (2-60 kg), the intraspecific scaling exponent for was 0.353.