Vase tunicate, Ciona intestinalis (Linnaeus, 1767) Type B (sensu Sato et al. 2012), was first recorded in Newfoundland (Canada) in Burin, Placentia Bay, by SCUBA divers conducting rapid visual surveys for invasive species on 19 September 2012. Follow-up surveys of Burin and adjacent communities were conducted in October and November 2012. Ciona intestinalis was present in relatively low abundance in Burin, but a well-established population was located in Little Bay, approximately 15 km north of Burin. Little Bay is located within Mortier Bay, an area of high vessel traffic and the possible introduction source of C. intestinalis. Further surveys are recommended to delineate the present distribution and monitor future dispersal of C. intestinalis in coastal Newfoundland waters. Due to the demonstrated high ecological and economic impacts of this species in other previously invaded regions, options for mitigating population growth and dispersal should be examined to minimize effects of this non-indigenous species.

The invasive and potentially pathogenic Asian fish tapeworm, Bothriocephalus acheilognathi, is reported for the first time from the vicinity of the Panama Canal zone, a region of international economic and environmental significance. The tapeworm was found in two cichlid species, Aequidens coeruleopunctatus and Cryptoheros panamensis in two tributaries of the Chagres River / Panama Canal drainage, Soberania National Park area, Panama. Sequence data from the ITS-1 region of the rRNA genome corroborate the identifications based on diagnostic morphological features. The tapeworm was not found in 201 of the other 15 species of fish belonging to 6 families that were collected during the same time. Using historical records, we argue that the tapeworm was likely introduced with the stocking of one of its principal hosts, grass carp, during early attempts to control aquatic vegetation in the Canal zone, and we predict that it is probably more widely distributed in the area, especially in Gatun Lake. The impact of this tapeworm on the native fish resources of Panama remains unknown, but is noteworthy for its presence in an already ecologically impacted region of the Neotropics.

We analysed the dynamics of the invasive Asian basket clam Corbicula fluminea in Lake Maggiore (Italy), recorded for the first time in August 2010. In order to reveal the extent of its dispersal, we monitored 30 locations along the lake for presence/absence of clams. This assessment of population structure, density and biomass is based on quantitative samples collected along the southern shoreline at four sites with diverse types of habitats. In the present study, the on-going process of Corbicula invasion was analysed from a spatial and temporal perspective. We compared density and size structure of the population among the sites (spatial distribution). We attempted to trace the colonization dynamics of the clams, so the invasion dynamics were tentatively reconstructed from spatial distribution of size/age groups and the contribution of the last recruited cohort to total population density along the lake littoral zone. Results from our surveys conducted in 2010–2011 have demonstrated that the Asian clam was well-established in the lake, thus about one-third of the lake (i.e. the southern basin) was already colonized by C. fluminea in 2011. Size frequency distribution in autumn 2011 further illustrated reproduction events and new recruitments. Population densities in Lake Maggiore were among the highest ever recorded in an Italian lake. Both the rapid spread of Corbicula in the littoral area and the relatively high densities, even at the most recently invaded sites, infer the potential ecosystem impacts associated with a dominant invasive species. Data reported here are not intended to be exhaustive since they concern only two years of investigations, so more detailed studies on both the ecology and invasive habits of this new alien species in Lake Maggiore are planned. The spatial approach used in the present study may clarify the dynamics of this invasion. Future monitoring might help us to disentangle the effects of spatial variability versus temporal succession during the establishment of the invasive species.

A new cyclopoid copepod species, Oithona davisae was discovered during regular monitoring along the western coast of the Black Sea in 2009–2012. In the short period since its discovery off the Bulgarian Coast, O. davisae populations have increased to become one of the dominant zooplankters, contributing up to 63.5–70.5 % of total mesozooplankton numbers in the Varna Bay and adjacent open sea waters. This species thrived in early autumn with a maximum density of 43818 ind./m³ in the eutrophic Varna Bay, but seasonal and annual abundance fluctuated widely during the investigation period. Temperature variability, changes in the phytoplankton community composition, and decreased abundance of gelatinous plankton were investigated as possible drivers for rapid increase in the new established population O. davisae in the Black Sea.

New observations are presented on the distribution of Palaemon elegans Rathke, 1837 in the Gulf of Finland and in the Archipelago Sea. P. elegans has spread and become established in the north-eastern Baltic Sea. Ovigerous females and juveniles were found, indicating that P. elegans reproduces in this area. The species was recorded, sometimes in high densities, along the southern coast of Finland between Naantali and Loviisa. Information on the distribution of P. elegans along the Estonian coast is also included.

Craspedacusta sowerbii Lankester, 1880 is reported for the first time from one of the largest Portuguese hydrographic basins. Three specimens collected in October 2012 represent the third record from Portugal and the first on the Sado hydrographic basin (south Portugal). We provide evidence on the range extension of C. sowerbii within Portuguese freshwater habitats, and outline the current lack of knowledge on the distribution in the southwest Iberian Peninsula.

The Chinese mystery snail (Bellamya chinensis) is an aquatic invasive species found throughout the USA. Little is known about this species’ life history or ecology, and only one population estimate has been published, for Wild Plum Lake in southeast Nebraska. A recent die-off event occurred at this same reservoir and we present a mortality estimate for this B. chinensis population using a quadrat approach. Assuming uniform distribution throughout the newly-exposed lake bed (20,900 m²), we estimate 42,845 individuals died during this event, amounting to approximately 17% of the previously-estimated population size of 253,570. Assuming uniform distribution throughout all previously-reported available habitat (48,525 m²), we estimate 99,476 individuals died, comprising 39% of the previously-reported adult population. The die-off occurred during an extreme drought event, which was coincident with abnormally hot weather. However, the exact reason of the die-off is still unclear. More monitoring of the population dynamics of B. chinensis is necessary to further our understanding of this species’ ecology.

Two specimens of the invasive American blue crab Callinectes sapidus were captured recently in the Ebro Delta, Spain. These constitute the first documented records of the species from Mediterranean waters of the Iberian Peninsula.

To date, the only alien xanthid crab recorded from the Mediterranean is Atergatis roseus (Rüppell, 1830). This species was first collected off Israel in 1961 and is now common along the Levantine coast. Recently a second alien xanthid species, Actaea savignii (H. Milne Edwards, 1834), was found off Israel and Turkey. A single adult specimen was collected in Haifa Bay in 2010, and two specimens were captured off Mersin, Turkey in 2011. Repeatedly reported from the Suez Canal since 1924, the record of the Levantine populations of A. savignii is a testament to the ongoing Erythraean invasion of the Mediterranean Sea.

In August 2012, a single painted spiny lobster (Panulirus versicolor) was captured in the coastal waters of Georgia, USA. The specimen was captured by a recreational fisherman in the South Brunswick River in water <1 meter deep. This is the first record of this non-native species in Georgia waters, and is believed to be the first record of P. versicolor in both the coastal waters of the continental USA and in the Atlantic Ocean.

Gibel carp Carassius gibelio (Bloch, 1782) has become an important non-native fish in all regions of Turkish inland waters with its wide distribution, high prevalence and impacts on native fish species through mainly reproductive and feeding interactions. This paper presents the first record of gibel carp caught on 15 December 2011 from Tersakan Stream in Muğla Province in SW Turkey. Size range of the species, possible introduction pathways and structure of the stream suggest that the species could well fit in its new environments and that further spread is likely.

The alien Ponto-Caspian gobiid Benthophilus stellatus was recorded in November 2011 for the first time in the lower reaches of the Dnieper River (Republic of Belarus). This species was captured in off-shore macrophyte beds, on a silty sand substrate, at a depth of approx. 0.6 m. A second individual was captured in August 2012. B. stellatus has invaded the Belarus waters from the Kiev Reservoir (Ukraine).

All Iberian populations of the genus Gobio have been ascribed to G. lozanoi to date. In northeastern (NE) Iberian catchments, the Gobio populations are not native and several species may have been involved in the introductions. To identify the species present, specimens were collected in several Ebro River and NE Iberian catchments. Their identification revealed the presence of two species, G. occitaniae and G. lozanoi, the former being the first record in the Iberian Peninsula. Gobio occitaniae was reported from one Ebro tributary and three NE Iberian catchments. The possible negative effects caused by competitive interactions between introduced Gobio species and native fish may warrant management actions to control or eradicate introduced populations.

The presence of Asian weather loach, Misgurnus anguillicaudatus, was confirmed for the first time in the River Meuse basin in September 2012. Initially, four specimens were caught in the Tungelroyse brook near the Belgium border. Based on settlement patterns in other parts of the world the species may become invasive. Potential ecological impacts should therefore be studied.

On 28 December 2012, a single specimen of the Red Sea goatfish Parupeneus forsskali was captured north of Beirut (33°55.472'N; 35°34.654'E) (Lebanon, eastern Mediterranean Sea). This species has been recorded earlier by visual sighting in only one Mediterranean location, in the vicinity of Mersin (Turkey). The most likely pathway for this Red Sea region endemic fish is the passage through the Suez Canal.