Influence of Delayed Metamorphosis on the Growth and Metabolism of YoungCrepidula fornicata(Gastropoda) Juveniles

Larvae of most marine invertebrates delay metamorphosis if they fail to contact an appropriate environmental stimulus. We conducted seven experiments with the slipper shell snail, Crepidula fornicata, to determine if delaying metamorphosis decreases juvenile fitness. Larvae were reared in the laboratory at 25° C on the unicellular alga Isochrysis sp. (clone T-ISO, 18 x 104 cells m1-1), and were induced to metamorphose after long, medium, or short periods of delayed metamorphosis. Long delay larvae were reared until they metamorphosed pontaneously in acid-cleaned glassware. Medium and short delay larvae were induced to metamorphose with adult-conditioned seawater or 20 mM elevations of KCl. Juveniles were subsequently reared for about one to two weeks at 25° C in the laboratory on a diet of T-ISO. Delaying metamorphosis generally did not lower juvenile weight-specific feeding rates, increase juvenile weight-specific respiration rates, or lower juvenile shell or tissue growth rates, any of which effects would suggest that delaying metamorphosis reduces juvenile fitness. Moreover, there was no indication that delaying metamorphosis reduced juvenile tolerance of temperature-salinity stress. Delaying metamorphosis of C. fornicata does not appear detrimental, at least for the first few weeks of juvenile life.