| Nematodes | Anguillicola crassus* | 2005 | Definite | Established | Fisheries Accidental (not Oyster), Natural Dispersal |
| Protozoans | Bonamia ostreae* | 1991 | Definite | Established | Oyster Accidental |
| Tunicates | Botrylloides violaceus | 1978 | Definite | Established | Hull Fouling |
| Crustaceans-Amphipods | Caprella mutica | 2007 | Definite | Established | Hull Fouling |
| Crustaceans-Crabs | Carcinus maenas | 1907 | Definite | Established | Ballast Water, Dry Ballast, Hull Fouling, Natural Dispersal |
| Tunicates | Ciona intestinalis | None | Definite | Established | Hull Fouling |
| Crustaceans-Amphipods | Corophium volutator | 1975 | Definite | Established | Ballast Water, Dry Ballast |
| Tunicates | Didemnum vexillum | 1982 | Definite | Established | Hull Fouling |
| Algae | Grateloupia turuturu | 2017 | Definite | Established | Ballast Water, Hull Fouling, Natural Dispersal |
| Protozoans | Haplosporidium nelsoni* | 2010 | Definite | Established | Oyster Accidental |
| Annelids-Polychaetes | Hediste diversicolor | 1955 | Definite | Established | Ballast Water, Dry Ballast |
| Crustaceans-Isopods | Ianiropsis serricaudis | None | Definite | Established | Ballast Water, Hull Fouling |
| Crustaceans-Isopods | Ligia oceanica | 2016 | Definite | Established | Dry Ballast, Hull Fouling |
| Mollusks-Gastropods | Littorina littorea | 1971 | Definite | Established | Dry Ballast, Hull Fouling, Natural Dispersal |
| Bryozoans | Membranipora membranacea | 1992 | Definite | Established | Hull Fouling, Natural Dispersal |
| Mollusks-Bivalves | Ostrea edulis | 1962 | Definite | Established | Oyster Intentional |
| Protozoans | Perkinsus marinus* | 1995 | Definite | Established | Oyster Accidental |
| Arthropoda-Insects | Petrobius brevistylis* | 1967 | Definite | Established | Cargo, Dry Ballast |
| Tunicates | Styela clava | 2007 | Definite | Established | Hull Fouling |
| Mollusks-Bivalves | Teredo navalis | None | Definite | Established | Hull Fouling |