The good status of the marine environment with regard to the quality descriptor of non-indigenous species resulting from human activities is achieved when the presence of non-indigenous species does not harm the ecosystem, namely: the number of newly introduced non-indigenous species into nature resulting from human activity for each assessment period, measured from the reference, is reduced to a minimum; the abundance and spatial distribution of established non-indigenous species, especially invasive ones, which have a significant adverse effect on species and EUNIS2 habitat types is limited; the proportion of species or spatial range of the EUNIS2 habitat types resulting from the adverse effects of non-indigenous species, in particular invasive species, is negligible.