THE EFFECT OF STARVATION ON ACQUISITION OF COMPETENCE AND POST-METAMORPHIC PERFORMANCE IN THE MARINE PROSOBRANCH GASTROPOD CREPIDULA-FORNICATA (L)

The duration of the precompetent period of development determines the obligate dispersal period for larvae of many benthic marine invertebra te species. This study considers the extent to which the onset of meta morphic competence in the gastropod Crepidula fornicata (L.) is contro lled by growth rate or the attainment of a critical, threshold size. P recompetent larvae of C. fornicata were starved in filtered seawater f or up to 6 days at 25 degrees C and subsequently tested for competence by 5 h exposures to 20 mM excess K+ in seawater. Control larvae were reared in excess phytoplankton suspension (Isochrysis galbana, clone T -ISO) and tested for metamorphic competence concurrently with starved individuals. Even though larvae stopped growing (and in fact lost up t o 37% of their initial ash-free dry weight) after being transferred to filtered seawater, many individuals became competent to metamorphose while being starved. These results suggest an allocation of limited en ergy stores to differentiation rather than to growth, and clearly indi cate that the onset of metamorphic competence is not size-dependent an d does not depend on growth for larvae of this species. Metamorphosed juveniles grew more slowly if they had been starved as larvae, indicat ing a link between larval nutritional experience and post-metamorphic performance.