New crustacean invaders in the Schelde estuary (Belgium)

This paper reports on the first records of three non-indigenous crustacean species in the Zeeschelde estuary (Belgium). All three species are native to the Western Pacific Ocean and are probably transported in ballast water or hull fouling. The isopod Synidotea laevidorsalis has been recorded earlier in Europe from two locations, in the south of France and in Spain. The present records constitute a range extension of more than 1000 kilometres to the north. The crab Hemigrapsus takanoi and the prawn Palaemon macrodactylus were found for the first time in the brackish reaches of the Schelde estuary. The finding of these species demonstrates the vulnerability of the estuarine system to the invasion of exotic species.