Specific dynamic action in the shore crab, Carcinus maenas (L.), in relation to acclimation temperature and to the onset of the emersion response

The rate of oxygen uptake ((M) over dot o(2)) of shore crabs following a. M period of fasting varied directly with acclimation temperature, with a Q(10) of 2.96 between 7degrees and 15degreesC and a Q(10) of 2.11 between 15degrees and 22degreesC. The factorial rise in (M) over dot o(2) following a. M meal (specific dynamic action [SDA]) ranged between 1.9 and 3.1 and varied with temperature, being highest at 15 degreesC and significantly lower at both 7degrees and 22 degreesC, despite similar ration sizes in all groups. At 7 degreesC, the SDA coefficient and magnitude were significantly lower than at 15 degreesC, possibly due in part to the inhibition of protein synthesis. Both the time to peak and the duration of the SDA response were inversely related to temperature. SDA coefficients were inversely related to the amount of food consumed. The critical oxygen tension of inspired water (P(I)o(2)), which evoked the emersion response in fasted animals, increased with temperature and further increased at each temperature when the animals were fed. Thus, the threshold P(I)o(2) evoking the emersion response is directly related to relative metabolic oxygen demand in Carcinus.