The main findings of the study, which performs a large-scale assessment of the native distribution range of the European marine non-indigenous species (NIS) found in at least one of the European seas (the Mediterranean Sea, the North-Eastern Atlantic Ocean, the Black Sea and the Baltic Sea), are:
- The vast majority of the marine non-indigenous species originate from the Western and Central Indo-Pacific, in particular species introduced in the Eastern Mediterranean through the Suez Canal such as the dusky spinefoot, the bluespotted cornetfish and the nomad jellyfish;
- A significant number of species originate from the Northern Pacific, Northwest Atlantic and Tropical Atlantic, in particular for species introduced in the Black Sea, Great North Sea and Western Mediterranean, such as the dead man's fingers, the American piddock and the warty comb jelly;
- There is a decreasing trend in new species introductions originating from the Northern Pacific.
The assessment of the origin and the associated pathways of the marine non-indigenous species can help scientists and national authorities to focus on non-indigenous species with specific origin and associated pathway of introduction. The findings provided by the current study are very useful for tailored management of specific primary pathways per marine subregion, supporting effective prioritisation efforts of marine non-indigenous species in order to prevent new introductions into unaffected areas: Marine non-indigenious species represent a major risk. They may exhibit invasive behaviour and change the ecosystem's structure and functions, impede the provision of ecosystem services and even result in negative socio-economic effects in coastal areas.
The new introductions of non-indigenous, alien species into unaffected areas can be prevented by handling their introduction pathways. These pathways include, after decades of rapid globalisation, increased shipping of ballast water, fouling on ships’ hulls, artificial canals, aquaculture, aquarium trade and tourism, which are responsible for the vast majority of non-indigenous species' arrivals into European Seas from other marine regions worldwide.