In the 1976-1986 period Atylus swammerdami was observed across the entire Belgian part of the North Sea with a low distribution frequency and in low densities (up to 60 ind./m2). A similar distribution pattern was also found in the 1994-2001 period. The most remarkable difference was the high distribution frequency near the southern Zeeland Banks. This is where the highest densities were observed (up to 170 ind./m2).
Degraer, S.; Wittoeck, J.; Appeltans, W.; Cooreman, K.; Deprez, T.; Hillewaert, H.; Hostens, K.; Mees, J.; Vanden Berghe, E.; Vincx, M. (2006). The macrobenthos atlas of the Belgian part of the North Sea. Belgian Science Policy. D/2005/1191/3. ISBN 90-810081-6-1. 164 pp. (look up in IMIS)