Is Corophium multisetosum Stock, 1952 an exotic invasive species in Europe? Distribution, habitat and recent observations in the Netherlands.

Corophium multisetosum Stock, 1952 has been found in several estuaries and water bodies in Europe ranging from fresh and brackish to salt water. The species appeared to be distributed over a wide geographic range from the Iberian Peninsula to the southern Baltic region and is recently found in theMediterranean and Gulf ofMexico, showing remarkable differences in ecology between populations. The recorded observations of the species in the Netherlands, however, remained restricted to a few smaller waters, and were published in grey literature. Recently, the species has been observed in a variety of waters in the southwestern part of the Netherlands and appears to be relatively common. The current study gives an overview of the recordings of C. multisetosum within its geographic range and its habitat preferences. The recent observations on distribution and habitat preferences of C. multisetosum in the Netherlands are compared with the findings in other parts of Europe. Seeming discontinuities in recorded ecology of the species in the Netherlands and over Europe are discussed. C. multisetosum appears to be very flexible in its behaviour and appears to tolerate a broad range of environmental conditions. Local environmental conditions (e.g., salinity and substrate) and related communities (in the Netherlands particularly the presence of the seemingly competing species Corophium volutator (Pallas, 1766) and Chelicorophium curvispinum (G. O. Sars, 1895)) determine the presence of C. multisetosum and the local behaviour and abundance of the species in the system. As the species shows a typical distribution pattern with many recent recordings, its origin and possible dispersal routes are discussed