in Belgian part of the North Sea: Ships: accidental with ballast water, sea water systems, live wells or other deck basins
Ketelaars, H. A. M.; Lambregts-van de Clundert, F.E.; Carpentier, C.J.; Wagenvoort, A. J.; Hoogenboezem, W. (1999). Ecological effects of the mass occurrence of the Ponto-Caspian invader, Hemimysis anomala G.O. Sars, 1907 (Crustacea: Mysidacea), in a freshwater storage reservoir in The Netherlands, with notes on its autecology and new records. <em>Hydrobiologia, The Hague.</em> 394:233-248.