Bl. Bayne, Physiological components of growth differences between individual oysters (Crassostrea gigas) and a comparison with Saccostrea commercialis, PHYSIOL B Z, 72(6), 1999, pp. 705-713
Pacific oysters (Crassostera gigas) of identical age from two genetically d
istinct lines, one fast growing and the other slow growing, were held at th
ree levels of ration and analysed for physiological traits to explain diffe
rences in their rates of growth. The data supported three hypotheses; faste
r growth was associated with faster rates of consumption of food, reduced m
etabolic rate at maintenance (i.e., at zero growth), and reduced metabolic
costs of growth. A comparison with the Sydney rock oyster, Saccostrea comme
rcialis, based on similar experiments on the two species, indicated that fa
ster growth of Pacific oysters depended on similar physiological difference
s; the mean metabolic costs of growth, however, were similar in the two spe
cies. It is suggested that a general model for genetically linked differenc
es in the growth rate of bivalve molluscs will need to include the processe
s of metabolic control rather than relying solely on an analysis of the ind
ividual components of the energetics of growth.