THE MARINE BIOLOGICAL ASSOCIATION OF THE UNITED KINGDOM The Marine Life Information Network for Britain and Ireland Marine Life Topic Note ALIEN, NON-NATIVE AND INVASIVE MARINE SPECIES

Definition An invasive, non-native, alien or exotic species is one that has been intentionally or accidentally released into an environment outside its native geographical range of habitat (Olenin et al., 2002). In the UK, according to Eno et al. (1997) the term ‘nonnative’ is used to indicate a species that has been established in UK waters, whilst ‘alien’ species are those that have been introduced via human activities but which have not become established and are incapable of establishing self-sustaining populations without deliberate intervention by ‘man’ (Eno et al., 1997). ‘Alien’ species are also referred to as ‘nonestablished’ species (Eno et al., 1997).