Rhithropanopeus harrisii (Gould, 1841) is an estuarine crab native to the East Coast of North America. This species has invaded both the West Coast of the United States and several European countries since the late 1800s where it has reportedly altered native ecosystems. This crab can tolerate a broad range of salinities and temperatures, which probably contributes to its success as an invader. In 1969, five specimens of R. harrisii were recorded in Panama, but subsequent surveys suggest it was not established. Here, evidence is reported of an established, reproducing population of R. harrisii in the Panama Canal. The crab’s entire distribution within this waterway remains to be determined and potential changes in its ecology, especially given the imminent expansion of the Canal, need to be evaluated.

Thirty of the 33 alien decapod crustacean species that have been reported off the Turkish Mediterranean coast are believed to have invaded the region via the Suez Canal, but only three of the species have been recorded along the Turkish Aegean coast. The marine biota of Gökova Bay, Datça Peninsula and Gulf of Fethiye, on the southern Aegean coast of Turkey, was studied by diving between 2002 and 2006. Of the eight Erythrean alien decapod species collected there, five constitute new records for the Aegean Sea and three are newly recorded from the Turkish coast of the Aegean Sea.

Single adult specimens of the Chinese mitten crab have been regularly found in the Volga River since the mid-1970s, most likely originating from the eastern Baltic Sea via the Volga-Baltic Canal. Three new records of Eriocheir sinensis H. Milne Edwards, 1853 are reported from the Kuibyshev Reservoir, Volga River, Russia, found in fishing nets in October 2002 and April-May 2007. The origins and possible vectors for the introduction of these crabs are discussed.

This is a special review on the native ranges of the zebra mussel (Dreissena polymorpha polymorpha) and quagga mussel (Dreissena bugensis). Revision of museum collections showed that the Dniepr Delta is a native locality of the quagga mussel, for example in the Lower Southern Bug and that Dreissena presbensis occurs in the Aegean Sea Basin in Greece. The native range of the zebra mussel includes Danube, Dniestr, Berezan, Southern Bug, Dniepr, Molochnaya, Don, Kuban, Kamchia, and Veleca river basins; isolated and semi-isolated relic estuarian reservoirs along the Bulgarian, Romanian, Ukrainian, and Russian Black and Azov seas coasts; and in zones of these seas influenced by freshwater. Invasive dreissenids in Turkish rivers are local species and subspecies. More recent locations of the dreissenid expansion within the Ponto-Caspian region (Lake Sasyk, Baraboj River, and Sukhoj Liman Basin for the zebra mussel; Dniestr River Basin for the quagga mussel) are described. One empty valve of Dreissena polymorpha andrusovi was found in the Taganrog Bay.

The ctenophore Mnemiopsis leidyi is one of the most cited invasive species due to its ecological and economical impact that occurred in the Black and Caspian Seas in previous years. Recent reports on the species presence in the Baltic and North Seas alarmed the scientific community. While the earliest report of M. leidyi in the Baltic was spring 2006, this paper indicates of the presence of M. leidyi in the Oslofjorden as early as autumn 2005, and discusses the possible invasion routes from its native range along the eastern coast of the Americas.

This study investigated the reproduction of non-native fish species, inferred from the presence of 0+ fish, in three English lowland rivers over an 8 year period. Evidence of self-sustaining populations was found for three non-native fish species, namely zander Sander lucioperca (in the River Trent and Warwickshire Avon), bitterling Rhodeus amarus (in the Trent) and carp Cyprinus carpio (in the Trent and Avon). Notwithstanding, such fishes are currently rare, accounting for <1% of the 0+ fish communities of these two rivers, and no non-native species were recorded from the Yorkshire Ouse. It is possible, however, that improvements in water quality and habitat, together with the potential effects of climate change, may facilitate consolidation and expansion of their populations, as well as those of other non-native fish species already present or introduced in the future. This could have repercussions for the ecology and management of non-native fishes in the UK.

We report on the occurrence and possible establishment of a non-native cichlid fish in a brackish-water system in the lower Chao Phraya River delta region, Thailand. Although, the possibility of some degree of introgressive hybridization can not be ruled out, Thailand specimens agree best with Mayan Cichlid “Cichlasoma” urophthalmus (Günther 1862). Our collections represent the first records of this New World, highly-invasive, euryhaline fish from Thailand and coincides with recent collections from Singapore. Positive identification of specimens as “C.” urophthalmus requires caution due to the diversity of the Cichlidae (>1,300 species), widespread introduction of many family members, variation within species, extensive interspecific overlap in characters, and proliferation of artificial cichlid hybrids (e.g., Flowerhorns). We first became aware of the Thailand population in 2005 when “C.” urophthalmus began appearing in the catches of local fishermen. We visited the site in November 2006 and obtained and examined voucher specimens. The abundance and wide size range of juveniles and adults in local ponds and an adjacent canal is evidence of natural reproduction. Because water bodies throughout the Chao Phraya delta are interconnected and subject to flooding, it is likely that “C.” urophthalmus is already established and is dispersing, but surveys and monitoring are needed to determine their exact geographic range. The Thailand population is compared to “C.” urophthalmus introduced into Florida (USA). Based on what is known about Florida “C.” urophthalmus, it is predicted that this cichlid will further invade coastal and inland waters in Thailand and elsewhere in Southeast Asia. This cichlid has a long history in the aquarium trade in Europe. However, there are no records from the wild in European waters and, because of the colder climate, the possibility of establishment in that region is relatively low.

This review is a first attempt to summarize data on the records and distribution of 240 alien species in fresh water, brackish water and marine water areas of Ukraine, from unicellular algae up to fish. A checklist of alien species with their taxonomy, synonymy and with a complete bibliography of their first records is presented. Analysis of the main trends of alien species introduction, present ecological status, origin and pathways is considered.

In total 61 aquatic alien species (AAS) are known from Belgian marine and brackish waters, eight of which are considered as cryptogenic species. The majority of the Belgian AAS have established self-sustaining populations, although for some species the establishment is uncertain or in need of verification. Prime introduction vectors are shipping, including small recreational craft, and aquaculture. Most AAS originate from the temperate northwest Pacific. The invasion rate has been increasing during the last two decades.

Two alien opisthobranch gastropod species are recorded from Greece in 2003-2004: Chromodoris annulata is a new record for the Mediterranean Sea, while Bursatella leachii is newly reported from Crete and Saronikos Gulf. Chromodoris annulata may have been introduced by shipping, whereas B. leachii has long been considered to have immigrated via the Suez Canal.

The first record of the quagga mussel Dreissena rostriformis bugensis (Andrusov, 1897) in Germany is described. This species has expanded its distribution area in Europe at a slower rate than the zebra mussel Dreissena polymorpha (Pallas, 1771). Recent records from the Danube in Romania and from an enclosed Rhine-Meuse estuary in The Netherlands, suggest that the Main-Danube canal and River Rhine have functioned as the dispersal pathway of the quagga mussel to The Netherlands. The record of this species in the River Main supports this hypothesis.

In 2006 and 2007 living individuals of Sinanodonta woodiana (Lea 1834) were collected from the eastern part of Romania. These samples represent the first report of this invasive species in the region and indicate that this alien species has colonized the main aquatic basins of Romania.

Dikerogammarus villosus has been recorded for the first time in the alpine lake – Lac du Bourget, French Alps. Low abundance of the alien species in gathered samples suggests that the colonization is just in its initial stage. Two native gammarid species: Gammarus fossarum (Koch, 1836) and G. pulex (Linnaeus, 1758) are still present in the lake. The invader has most probably reached the lake through the Canal de Savières joining the lake to the Rhone River in which it has been already present since late 1990s.

The invasive Ponto-Caspian mysid Limnomysis benedeni Czerniavsky, 1882 has been recorded for the first time in August 2007 at three sites on the River Pripyat (the Belarusian part of the inland European central invasion corridor). This species occurs in the onshore shallow zone (depth 0.2-0.3 m) with aquatic vegetation and high temperature. High abundances of this species have been observed in port bays. Most likely, this invasive mysid entered the River Pripyat basin from the Dnieper Reservoirs where it was intentionally introduced after 1960.

The invasive Ponto-Caspian gobiid fish Proterorhinus marmoratus has been recorded in August 2007 for the first time in the upper and middle sections of the River Pripyat (Republic of Belarus), a principal invasion corridor of European inland waters. This species was found mainly in river oxbows characterized by depths of 0.3–1.0 m, aquatic vegetation and muddy substrata. Tubenose goby invasion of the River Pripyat basin was via reservoirs on the River Dnieper, which was invaded by the species during the late-1970s.