Evidence for the direct settlement of Mytilus edulis larvae on adult mussel beds

Investigations on intertidal mussels Mytilus e d u l ~s L. on an exposed rocky shore in the west of Ireland during 1983 to 1986 revealed a settlement pattern which differs from that reported elsewhere, particularly in Britain Analysis of the population structure showed the frequent presence of cohorts of ind~viduals < 500 pm shell length These cohorts appeared in the population at times and with a size range which indicates direct settlement from the plankton on the adult beds. M. eduhs larvae may settle directly on adult beds without the initial prlmary phase on filamentous substrates postulated by the primary/secondary settlement model.