Because of the upcoming importance of the reef building polychaet Lanice conchilega on the Belgian Continental Shelf, the dep. Marine biology of University Ghent started in coöperation with the Laboratory of Aquatic Ecology of the Katholieke Universiteit Leuven a large-scale survey of the genetic structure of Lanice conchilega. The genetic structure of Lanice conchilega points to isolation by distance as measured with mitochondrial markers.