| Main Ref. | Gollasch, S. and S. Nehring, 2006 |
| To | North Sea. |
| FAO area | Atlantic, Northeast |
| From | Northwest Atlantic. |
| FAO area | Atlantic, Northwest |
| Year | 1983 |
| Range | |
| Period | 1975-present |
| Established in the Wild | Unknown |
| Established in Aquaculture | |
| Significant Ecological Interactions | yes - adverse |
| Significant Socio-economic Effects | |
| Introduced by | |
| Reason | ballast water |
| Other Reason | |
| Comments | Reintroduced in the Baltic Sea in 2004. Introduced as Merenzelleria neglecta Sikorski et Bick, 2004 in the Baltic Sea in 1985 and in the North Sea in 1996. Causes competition, habitat modification and predation. |