Neozoa

Muskrat (Ondatra zibethicus)

The muskrat is native to North America but has spread throughout Europe andAsia. It has been imported toEuropefor fur cultivation.

The muskrat accepts almost any flowing or still waters as habitat. It feeds primarily on plants, during months of low vegetation, however, it complements on mussels and insect larvae.

Therefore, the muskrat is an important threat to small mussel populations.

Raccoon (Procyon lotor)

The raccoon is native to North America but spread throughoutEuropeafter it escaped from cages or has been abandoned. The raccoon is an adaptable, primarily nocturnal predator, that occurs in water-rich mixed- and deciduous forests. The raccoon is an omnivore and therefore a threat to native mussels.

Asian clam (Corbicula fluminea)

The Asian clam is native toChinaandTaiwan. Ballast water has carried this species to North and South America as well asEurope. Intense reproduction means that it can propagate rapidly.

Zebra mussel (Dreissena polymorpha)

The zebra mussel now occurs in flowing and still waters in Europe andNorth America. However, its origin lies in the tributaries of the Caspian andBlack Sea. Similarly to the Asian clam, it has been dispersed by ship traffic.

The mussels can clog up sewage and water service pipes of energy plants for example. It also attaches onto other mussels and snails and restricts their movement..

Signal crayfish (Pacifastacus leniusculus)

The signal crayfish originates in North America and has been released inEurope.

It resembles the European crayfish (Astacus astacus) but its carapace is less thorned. The signal  crayfish is an omnivore that occurs predominantly in cold, oxygen-rich rivers. It also tolerates warmer temperatures and can therefore be found in small lakes.

The signal crayfish also feeds on mussels.