Station 11 - English

Invasive Species Station

Unwanted guests

National parks are refuges for indigenous nature. However, we have already introduced hundreds of exotic plant and animal species, which to some extent have also become established in Eifel National Park. Not all of them are comparatively harmless species such as the mouflon, a wild sheep originally native only to Corsica and Sardinia, or the racoon introduced from North America.

Crayfish plague

The introduction of North American relatives such as the Cambarus and signal crayfish over 100 years ago became a serious threat to native European crayfish. The North American crayfish, which are significantly more robust, have not only displaced the noble crayfish and the stone crayfish across Europe; above all, they transmit the crayfish plague, a mould disease to which they themselves are largely resistant, but which is fatal to European crayfish.

National park survival area

The lethal spores of the crayfish plague are transmitted via fish, birds, and even fishing gear. For this reason, only in very isolated refuges do noble and stone crayfish still have a chance to survive. The near-natural flowing waters of Eifel National Park offer such survival areas.

What type of nature do we want?

There was probably never any malicious intent involved when foreign plant and animal species were established or released in Europe. Those who release aquarium inhabitants that have grown too large into the nearest pond or brook are unaware of the dangers associated with this.

Once a non-native species has become established in nature, it is almost impossible to suppress. Where it competes with native species, it is not uncommon for the latter to be completely displaced.

A few prominent examples of such invasive species are listed below.

On the left side of this station is a model of a brook trout that you can touch.

• River cooter turtle

Once purchased as a delightful baby reptile, the quickly growing river cooter turtle suddenly becomes a problem – and is “disposed of” in the nearest body of water. However, the diet of this omnivore includes some species of newt, frog and fish that are on the Red List of endangered native species.

• Rainbow trout

Beginning in 1875, the rainbow trout became established in almost all of Europe. Although it is a subject of debate among fish experts, many say that the rainbow trout has displaced the native brook trout in many places – due to particular spawning habits, and a tolerance for higher water temperatures, a lower oxygen content and a greater degree of water pollution.

• Mink

The European mink, formerly also native to the Eifel, has almost completely disappeared from Europe. Fur trapping and the pollution and channelling of flowing waters were responsible for this – as well as the escape from fur farms of the much more robust American mink, which competes successfully for the last remaining natural river habitats.

• Japanese knotweed

Once introduced as livestock fodder and as an ornamental plant, Japanese knotweed has developed into a “pest” in Europe. It completely displaces natural embankment vegetation, but does not contribute to the soil stabilisation that is so important in such locations. Japanese knotweed is extremely difficult to control, because even a tiny root residue can develop into a new plant.

• Giant hogweed

Giant hogweed introduced from the Caucasus readily colonises brook and river floodplains where, with its foliage reaching a height of up to four metres, it systematically displaces native flora. It is dangerous to come into contact with its sap, especially for children. In combination with sunlight, the sap causes burn blisters and inflammation, which often leaves ugly scars.