Effects of early fouling communities formed in the field on settlement and metamorphosis of cyprids of the barnacle, Balanus amphitrite Darwin

Effects of early fouling communities formed in the field on cyprid settlement in the laboratory have been examined. Glass coverslips (18 x 18 mm; total area 324 mm(2)) were placed daily, in a holder immersed 50 cm below the sea surface in Tokyo Bay and were collected on day 10. Each of the ten filmed coverslips, of successive growth stages, were placed in a polypropylene bottle containing 8 mi filtered seawater, into which ten cyprids were added. Bottles were incubated at 25 degrees C in the dark, and juveniles on the coverslip were counted after 48 h. Film volumes were estimated by a confocal laser microscope equipped with a 3D image analyzer. Although films grew at different rates and in different fashions from experiment to experiment, they showed a similar pattern of induction of cyprid metamorphosis when the film volume was used as a parameter. The percentage metamorphosis increased as the film volumes increased, up to 0.1-1 mu m(3) mu m(-2), and decreased thereafter. Therefore, the film volume is most likely to influence cyprid settlement.