Laonome calida Capa, 2007, a feather-duster worm discovered in 2007 in estuaries and open water of tropical and subtropical Australia, was recently found at many locations in fresh and brackish waters of the delta region of the rivers Rhine, Meuse, and Scheldt in the Netherlands. Morphological differences between specimens from Australia and the Netherlands are insufficient to warrant specific distinction. A recent translocation from Australia to Europe, or from a third country to both, may explain the disjunct distribution of this species. A table with translocated and cryptogenic sabellids reported to date is provided.

The clubbed tunicate Styela clava (Herdman, 1881) is an invasive, solitary, club-shaped organism native to the western Pacific. S. clava has spread far beyond its native range into temperate waters worldwide, including those of Long Island Sound (LIS) on the northeastern coast of the United States. A visual inspection of public and private commercial and recreational marinas and docks located along the shores of LIS was conducted between June 2011 and September 2013. The wrack lines of public beaches and other public coastal areas were also surveyed. S. clava was found at 77.8 % of the sites surveyed indicating it has now fully colonized the Sound. It is strongly suggested that managers of neighboring waters be vigilante, and be prepared to take steps to mitigate negative impacts, should the species spread further south along the Atlantic Coast of the United States.

In March 2013 the Asian kelp Undaria pinnatifida (Harvey) Suringar, 1873 was discovered in Rangaunu Harbour, northern New Zealand (34°89′05″S, 173°29′54″E), a site where water temperatures typically range between 14 and at least 24C. This is the first report of Undaria in subtropical parts of New Zealand and demonstrates that Undaria is capable of invading marine environments throughout the country. The presence of healthy juvenile and reproductive sporophytes during late summer (SST >21C) is of particular concern as juvenile Undaria sporophytes have previously only been recorded during summer in cooler water regions. This discovery indicates a previously unreported deviation from a winter annual lifecycle at subtropical temperatures and an increased risk of invasion impacts for subtropical sites worldwide.

Bivalves of the family Teredinidae are among the most destructive wood-boring species in the sea. We report the first occurrences of the warm-water shipworm Teredo bartschi in Mersin, Turkey, and Olhão, Portugal. The colonisation of the site in Mersin is likely to have occurred by rafting adults originating from the Red Sea, which passed through the Suez Canal (lessepsian migrants). T. bartschi might have been introduced in Olhão Harbour, Portugal, either by rafting adults with larvae transported by currents or by larvae transported by ships in ballast water. These seem to be the first published records of established T. bartschi populations in the Mediterranean and in northeast Atlantic.

Examination of mud from crevices beneath Pacific oysters Crassostrea gigas (Thunberg, 1793) in The Netherlands revealed the presence of the Pacific amphipod Monocorophium uenoi (Stephensen, 1932), which was not recorded previously from the Atlantic. The most likely introduction vector to The Netherlands was import of shellfish. The only location where the amphipod was found was the center of shellfish trade, Yerseke.

Lake Balaton in Hungary is the biggest shallow lake in Europe and has two main invasion pathways: a canal (Sió Canal), which connects the lake to the watershed of the River Danube and fishponds on the south of the lake. The spiny-cheek crayfish was intentionally introduced to Hungary in the 1950s for farming, and was first detected in the wild in the Újpest-branch of the River Danube in 1985. Its occurrence in the Sió Canal was first reported in 2004, and a dead specimen was found in Lake Balaton. In our study the species is described from a fish pond with a possible connection to the lake.

Callinectes sapidus (Crustacea, Decapoda, Portunidae) and Percnon gibbesi (Crustacea, Decapoda, Percnidae) are respectively reported from two Italian localities: Basento river (Basilicata, Ionian Sea) and Montecristo Island, Tuscan Archipelago (Northern Tyrrhenian Sea). Data on collection sites and discussion regarding their present distribution are provided.

In 2013, 71 specimens of Perccottus glenii Dybowski, 1877 were caught in Ukraine in a tributary of the Southern Bug River, known as the Hirskyi Tikych. Present study confirms the expansion of this invasive species in Ukraine and also in Europe.

Neopomacentrus cyanomos (Bleeker, 1856), a common damselfish from the Indo-west Pacific, is reported from the southern Gulf of Mexico based on 134 visual observations and the collection of 15 specimens from coral south of Veracruz, Mexico. It was sighted in schools containing 5 to 30 individuals at depths of 2 to 21 m. The introduction and subsequent colonization of this alien species is probably the result of transport in the ballast water of international ships.

The first sighting of Abudefduf individuals from Maltese (Central Mediterranean) coastal waters is reported. The individuals (6-7) were photographed in the field but were not collected. The pattern of body colouration of these individuals is consistent with that reported by most previous authors for A. saxatilis, marking the first record of this Atlantic species from Maltese waters.