Scaling of enzyme activity in larval herring and plaice: effects of temperature and individual growth rate on aerobic and anaerobic capacity

Herring Clupea harengus and plaice Pleuronectes platessa were reared at 8 a nd 12 degrees C from the fertilized egg to a larval age of up to 600 degree -days. Soluble protein as well as the activities of both citrate synthetase (CS) and lactate dehydrogenase (LDH) were measured in homogenate supernata nts of individual larvae at 10 degrees C. Scaling factors were calculated u sing the expression y=ax(b) where y is the enzyme activity, x the protein c ontent of the larva a is a constant and b the scaling factor. All scaling f actors showed significant differences between the species. Within species, the scaling factors for CS activity were either small or not significantly different between the two rearing temperatures, but the scaling factors for the LDH activities were significantly different at the two temperatures fo r both species. Herring larvae, which had higher LDH activities when newly hatched, showed smaller scaling factors for LDH (b=1.42 at 8 degrees C and b=1.07 at 12 degrees C) than plaice (b=2.11 at 8 degrees C and b=1.45 at 12 degrees C). Activities converged as the larvae grew. The results of the cu rrent study together with reanalysis of data from the literature indicate a n increasing aerobic and anaerobic capacity during the larval stage of fish es (positive allometry). (C) 2000 The Fisheries Society of the British Isle s.