Advance of exotic animals and plants unstoppable

14/03/2006 14:00

Flora and fauna in the Netherlands are changing continually. New species emerge and existing species disappear. Over 10 percent of many animal and plant groups were imported into the Netherlands. The amount of exotic species of plants and animals has more than doubled since 1900.

Species come and go

Exotic species are species introduced into the Netherlands from their natural habitat by human intervention which are able to reproduce in the wild. If these new species manage to survive here and complete their life cycle, they will become part of the Dutch fauna and flora.

Share of exotic species in Dutch fauna and flora

Share of exotic species in Dutch fauna and flora

Deliberately or inadvertently

A number of exotic plants and animals were imported into Europe or the Netherlands, such as the Japanese oyster for oyster farming, the muskrat for its fur and the North American wild cherry for forest improvement. Other species ended up here inadvertently, like the brown rat and the American jackknife clam, a shellfish. These species were, for instance, brought to the Netherlands aboard ships. The Egyptian goose escaped from captivity and the Caspian mud shrimp could reach the Netherlands after opening of the Main-Donau canal.

Vertebrates: amount of exotic species by period

Vertebrates: amount of exotic species by period

Molluscs: amount of exotic species by period

Molluscs: amount of exotic species by period

1.3 billion euro worth of damage

Exotic species can cause massive financial damage. Annual damage is estimated at 1.3 billion euro. This damage includes costs of control of exotic infectious diseases. The muskrat’s tunnelling below water level undermines dike foundations and the water pennywort, a water plant, grows so fast over a short period of time that it can jeopardise water discharge. Exotic plants and animals can also cause damage to the environment. Various exotic species, like the Japanese oyster compete for food or space with native species, other species pass on diseases to indigenous plants and animals.

Lodewijk van Duuren