Invasive alien species
Non-native or alien species are animals, plants, fungi and micro-organisms from other parts of the world that have been introduced to a new natural environment at the hands of humans. The number of alien species in Europe is on the rise: currently, the counter stands at more than 12 000. Many of these species are deliberately brought to Europe because they are beautiful, useful or commercially valuable. Others are introduced unintentionally, when, for example, they get caught up in other goods or are accidentally transported via ships or vehicle.
Invasive alien species (IAS) are non-native animals and plants whose introduction and spread have serious negative impacts on the environment. Fortunately, not all exotic species cause problems in their new environment: the vast majority find it difficult to survive, grow or reproduce there. About 10-15% of alien species introduced to Europe also become invasive and proliferate locally, often due to a lack of predators and parasites that normally keep these species under control.
Pictures: larva of the voracious Lithobates catesbeianus (GBNNSS), stream overgrown with Impatiens glandulifera (Jo Packet), pond almost completely occupied by Myriophyllum aquaticum (Jo Packet); a young specimen of the crab Eriocheir sinensis (Bram D'hondt).