The colonisation of the IJsselmeer by the Caspian mud shrimp

The Caspian mud shrimp has established successfully in the Netherlands and has ousted some of the original fauna.

Trends

The Caspian mud shrimp colonised the IJsselmeer in the 1990s. In 1992 it was found chiefly in the west of the lake, but by 2000 it had spread throughout the lake. At the same time, the native mud shrimp Corophium lacustre declined, presumably because it cannot compete.

Origin

Many of the exotics in the Netherlands are from other continents, but this species has arrived from southeastern Europe, via the canals built to link rivers that were formerly isolated from each other. The Caspian mud shrimps travelled via the Dnieper, Vistula, Oder, Elbe and Rhine.

Another exotic, the killer shrimp, arrived in the Netherlands the same way. It reached the Rhine after the Main-Danube canal was completed in 1992. Its arrival has led to the decline of other species such as the zebra mussel (also an exotic from Eastern Europe). Various other species have reached the Netherlands via the Main-Danube canal and settled here: two possum shrimps, a freshwater isopod and a flatworm.

Technical note

The data are from RIZA's monitoring networks. The mud shrimps have been counted at several dozen locations in the IJsselmeer.

References

Noordhuis, R. (red.) (2000). Biologische monitoring zoete rijkswateren. Watersysteemrapportage IJsselmeer en Markermeer. RIZA-rapport 2000.050. RIZA. Lelystad.