| Species |
Recipient region |
Date of the first record |
|
| Acrochaetium mediterraneum | Turkey / Black Sea | 2000 - 2009 |  |
| Acrochaetium microscopicum | Turkey / Black Sea | 2000 - 2009 | |
| Acrochaetium moniliforme | Turkey / Black Sea | 2000 - 2009 | |
| Acrochaetium pacificum | Australia / Bass strait | 1981 | |
| Acrochaetium rosulatum | Bulgaria | 1990 - 1999 | |
| Acrochaetium rosulatum | Turkey / Black Sea | 2000 - 2009 | |
| Acrochaetium savianum | Netherlands | 1960 - 1969 | |
| Acrochaetium subpinnatum | Turkey / Black Sea | 2000 - 2009 | |
| Acromegalomma claparedei | Italy / Adriatic Sea | 1987 | |
| Acrothamnion preissii | France / Western Mediterranean | 1981 | |
| Acrothamnion preissii | Italy / Adriatic Sea | 2007 | |
| Acrothamnion preissii | Italy / Central Mediterranean | 1996 | |
| Acrothamnion preissii | Italy / Western Mediterranean | 1969 | |
| Acrothrix gracilis | France / Western Mediterranean | 1993 | |
| Actaea savignyii | Israel | 2010 | |
| Actaeodes tomentosus | Greece / Eastern Mediterranean | 2013 | |
| Acteocina mucronata | Greece / Eastern Mediterranean | 1991 | |
| Acteocina mucronata | Israel | 1986 | |
| Adelosina carinatastriata | France / Biscay Gulf | To 2007 | |
| Aeolidiella indica | Italy / Western Mediterranean | 1968 | |
| Aequorea macrodactyla | Israel | 2013 | |
| Aerococcus viridans | Ireland | 1961 | |
| Aerococcus viridans | United Kingdom (Britain) / Celtic seas | 1985 | |
| Aeromonas salmonicida salmonicida | Norway / Barents Sea | 1986 | |
| Aeromonas salmonicida salmonicida | Norway / North Sea | 1986 | |
| Aeromonas salmonicida salmonicida | Norway / Norwegian Sea | 1986 | |
| Aetea anguina | Australia / Bass strait | 1887 | |
| Aetea anguina | Spain / Canary Islands | To 2003 | |
| Aetea ligulata | Spain / Canary Islands | To 2003 | |
| Aetea longicollis | Spain / Canary Islands | To 2003 | |
| Aetea sica | Spain / Canary Islands | To 2003 | |
| Aetea truncata | Spain / Canary Islands | To 2003 | |
| Afrocardium richardi | Israel | 1997 | |
| Afropinnotheres monodi | Portugal / Iberian Coastal | To 2019 | |
| Afropinnotheres monodi | Spain / Iberian Coastal | 1995 | |
| Agardhiella subulata | France / Western Mediterranean | 1984 | |
| Agardhiella subulata | Italy / Adriatic Sea | 2003 | |
| Agardhiella subulata | Italy / Central Mediterranean | 1987 | |
| Agardhiella subulata | Italy / Western Mediterranean | 2007 | |
| Agardhiella subulata | Netherlands | 1998 | |
| Agarophyton vermiculophyllum | Belgium | To 2011 | |
| Agarophyton vermiculophyllum | Canada / Gulf of Alaska | 2006 | |
| Agarophyton vermiculophyllum | Denmark / Baltic Sea | 2003 | |
| Agarophyton vermiculophyllum | Denmark / North Sea | 2005 | |
| Agarophyton vermiculophyllum | France / Biscay Gulf | 2005 | |
| Agarophyton vermiculophyllum | France / Celtic seas | 1996 | |
| Agarophyton vermiculophyllum | France / English Channel | 1993 | |
| Agarophyton vermiculophyllum | Germany / Baltic Sea | 2005 | |
| Agarophyton vermiculophyllum | Germany / North Sea | 2002 | |
| Agarophyton vermiculophyllum | Ireland | 2012 | |
