Descriptions of the seasonal cycles of abundance of the dominant zooplankters of Yaquina Bay, Oregon, USA, are derived from a seven year series of net samples taken at two downstream stations. The summer dominants are forms distributed to the north, along the American coast. Winter dominants have southern affinities. This cycle is associated with the annual cycle of coastal surface currents: from north to south in summer, reversed in winter. There are no persistent trends in the abundance data from year-to-year.