What fish biologists should know about bivalve shells

Similarities between shell and otolith growth patterns are numerous. Both have been shown to have subdaily and daily increments, fortnightly variations, and annual patterns. Some of the less obvious common features include the production of irregular microgrowth patterns at low temperature, increased transparency at high temperature, reduced increment clarity in field to laboratory transferred individuals, and uncoupling between somatic growth and growth of the calcified structure. A principal difference between shells and otoliths is that while microgrowth increments are found in bivalve larvae, presence of internal daily increments has not been verified for any species. Applications of shell and otolith growth patterns have also been similar. Both have been used to reconstruct the effect of environmental and ontogenetic events after they have taken place and to obtain age data critical for estimating growth rate, recruitment, and survivorship. Recent evidence suggests that growth in these calcified structures has the potential to provide information on physiological processes. Evidence is provided for bivalves that respiration rates could potentially be predicted from shell growth rates. (C) 2000 Elsevier Science B.V. All rights reserved.