De Aziatische Korfmossel, Corbicula fluminea, in het Ketelmeer

From recent observations (August and October, 1993) it was concluded that the colonization of the immigrant freshwater clam Corbicula fluminea into the drainage area of the River Rhine moved forward into Lake Ketelmeer. In this lake, the River IJssel discharges. It is one of the Rhine branches in The Netherlands. Lake Ketelmeer is part of the Lake IJsselmeer area, which means further colonization possibilities for both species. Colonization by C. fluminea and C. fluminalis of the Rhine in general is discussed.