LARVAL DISPERSAL AND RECRUITMENT OF HALIOTIS-DISCUS-HANNAI AND TEGULASPP ON MIYAGI COASTS, JAPAN

The spatial dispersal and vertical distribution of larvae of Haliotis discus hannai and Tegula spp. were examined in relation to storm event s in Miyagi Prefecture, Japan, from 1983 to 1993. Epidemic spawning is induced by typhoons and minor storms. After typhoons, larvae are disp ersed in coastal waters up to 3 km from shore to a depth of 30 m and l ater are advected toward the coast by onshore winds. After minor storm s, larvae are locally dispersed close to shore. Larvae of H. discus ha nnai and Tegula spp, become vertically stratified and settle on the su bstratum at depths in accordance with the vertical depth range of thei r larvae, Strong settlements of H. discus hannai of up to 200 m(-2) we re recorded around headlands, with average survival rates of about 13% per month in the first 2-3 months. The adaptive significance of dispe rsal over short and long distances is considered.