In both periods Urothoe poseidonis mainly occurred in the near-coastal zone, with the exception of the eastern coastal zone but with the inclusion of the western Flemish Banks. Whereas the species was only found 15 times and with a maximum density of 50 ind./m2 in the 1976-1986 period, the species had a higher distribution frequency and maximum density (750 ind./m2) in the 1994-2001 period. In the latter period the species was mainly found in the western near-coastal zone.
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)