In recent years, the distribution of several non-native crayfish species in Flanders has increased significantly. Several new species have been detected that are likely to increase their ranges in the coming years. Watercourses are also strongly affected by invasive, non-native plant species.
These species can cause significant ecosystem changes, impacting on native species, infrastructure and recreation. Changes in macrophyte communities also result in negative assessment in the context of reporting for the European Water Framework Directive (WFD). Informed management is recommended, with rapid response to early-invasive species more effective than the control of late-invasive species. Many of these species are on the 'Union list' of invasive alien species of the EU IAS Regulation, requiring surveillance and the adoption of appropriate preventative actions and management measures.