SHORT COMMUNICATION LACTATE DYNAMICS DURING LOCOMOTOR ACTIVITY IN THE BLUE CRAB, CALLJNECTES SAPID US

In recent years there has been considerable interest in the effects of locomotor activity on respiratory gas exchange and acid-base balance in the Crustacea (reviewed by Herreid, 1981; McMahon, 1981; McMahon & Wilkens, 1983). However, the partitioning of energy metabolism between aerobic and anaerobic pathways during crustacean locomotion is still poorly understood (Herreid, 1981; Full & Herreid, 1984). Booth, McMahon & Pinder (1982) recently reported that the highly active swimming crab, Callinectes sapidus, elevates oxygen uptake rate to a steady state level within 2 min after the onset of enforced swimming activity. In contrast, several terrestrial crabs studied by Herreid and co-workers (Herreid, 1981) showed sluggish aerobic responses to exercise, and did not attain steady state levels of oxygen uptake during 10—20 min of treadmill running at various speeds. The short 'oxygen deficit ' period displayed by C. sapidus at the start of exercise resembles the oxygen uptake kinetics of highly aerobic mammals (cf. Cerretelli, Pendergast, Paganelli & Rennie, 1979) and suggests that C. sapidus might be less dependent on anaerobic metabolism to fuel locomotion than some of the terrestria