In the 1976-1986 period Echinocardium cordatum was mainly found near the Flemish Banks (maximum 50 ind./m2) whereas it was absent in the eastern coastal zone and near the Hinder Banks. In the 1994-2001 period the species is clearly distributed more widely: E. cordatum was only absent in the eastern coastal zone and reached densities up to 200 ind./m2. As the species lives burrowed in the sand (up to 20 cm deep) there is a real chance that the Van Veen grab fails to scoop up E. cordatum. Consequently, the species may have a broader distribution than mentioned here.
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)