Growth efficiencies and factors controlling size in some mytilid bivalves. Especially Mytilus edulis L.: review and interpretation

Abstract

Data from the literature on rates of growth and metabolism, mainly in Mytilus edulis, but also in M. californianus and Modiolus demissus have been used in an attempt to estimate the maximum rates at which mussels can convert absorbed food energy into growth and reproduction, and to evaluate which factors control these maximum net growth efficiencies. It is concluded that high maximum growth efficiencies can be maintained at a constant level up to a certain critical body size above which the maximum growth efficiency declines with increasing size. The critical body size at which growth efficiency starts to decline is independent of the initial level of maximum growth efficiency.

The maximum body size that can be attained depends upon the body size at which the growth efficiency starts to decline and the rate at which it is declining.

It is argued that the declining growth efficiency above a critical body size results from a decelerating mean rate of water transport. The reduced rate of water transport, that is, of food uptake, may be the main factor that determines the maximum size the species, or the individual, can attain.