An overview is presented of the metazoan alien biota recorded from the Mediterranean coast of Israel. Of the 296 alien species, 284 have been introduced from the Red Sea/Indo West-Pacific through the Suez Canal. A brief history of the research on introduced species along the Israeli coast is presented along with the list of species, and their ecological and economic impacts are discussed.

This risk assessment study follows the environmental match of donor and recipient regions of ballast water and the voyage duration as risk quantifiers. The ports considered were Gothenburg (Sweden), Copenhagen (Denmark), Kiel (Germany), Klaipeda (Lithuania), Kemi, Tornio and Raahe as one port region (Finland), and Sköldvik/Kilpilahti (Finland). All selected Baltic ports have at least one donor port in the highest risk category, all extreme and high risk donor ports are located in Europe, but mostly outside the Baltic Sea. The most frequently reported high-risk donor ports are Rotterdam (6 times), Bremerhaven (5), Amsterdam (4) and Antwerp (3), and most high-risk donor ports are the major hub ports in Europe. The paper concludes with ballast water management scenarios for intra-Baltic shipping and for vessels engaged on voyages outside the Baltic.

One-hundred-and-twelve alien species are recorded for marine, brackish and freshwater environments in Ireland, of these sixty-eight are thought to be established. Their arrival has been mainly due to shipping, aquaculture and the ornamental industries. There are almost thirty species considered to be invasive and some that have arrived recently may have significant future impact. The majority of recorded alien species will have arrived since 1950. Usually these species appear in Britain or Northern Europe before occurring in Ireland. The majority of the marine species will have originated from the North Pacific Ocean whilst most of the freshwater species will have originally been sourced from North America. The sixty-four cryptogenic species arise out of the uncertainty of their origin or as to how they will have arrived. Ireland being a recently deglaciated island and separated from the continental land mass will have acquired the majority of its biota since the last glacial retreat making distinction between native and alien species more difficult.

The invasive alga Sargassum muticum has recently been reported in the Firth of Lorn, west coast of Scotland. This represents the first sighting of the species north of the Kintyre Peninsula, a land barrier that had been expected to slow the northwards spread of S. muticum. This paper presents a thorough review of literature concerning the dispersal and establishment of this invasive alga and predicts potential dispersal trajectories and likely areas for future establishment in Scotland. From previous dispersal rates, S. muticum is likely to spread throughout the west coast of Scotland in the next few years, predominantly via natural pathways although anthropogenic vectors may also contribute to dispersal. Sheltered and moderately exposed sea lochs and shorelines, on the west coast of Scotland in particular, are likely to provide favourable conditions for the establishment of persistent populations of S. muticum. Conditions on the north and east coasts of Scotland were considered less favourable, both for the dispersal and establishment of S. muticum. The spread of S. muticum is unlikely to cause serious widespread ecological impacts, however, it does have the potential to cause economic damage to the aquaculture industry which is a major employer on the west coast of Scotland. The establishment of dense highly visible canopies would also constitute a degradation of the natural heritage value of Scottish shorelines. It would be prudent to investigate means of preventing persistent populations from establishing in areas of economic importance or with high natural heritage value.

The immigrant ascidian Styela clava Herdman is native to the northwest Pacific. It was first found in British waters in 1953. The spread of this sessile invertebrate in western European waters during the fifty years since its introduction is described, and the current distribution is reviewed with reference to physical constraints and the dispersal methods available. Natural dispersion may account for the spread to neighbouring sites, but isolated populations can best be explained by man-aided dispersal. Suitable vectors are proposed and the potential for further spread is discussed.

Ephyrae and adult medusae of Phyllorhiza punctata were found in 2005 and 2006 in the Ionian Sea, Greece. The youngest ephyrae had a diameter of 1.5 mm and already contained symbiotic zooxanthellae. The biggest medusae, with 45 cm bell diameter, were found in September 2005 in the Bay of Vlyho on the Ionian Island Lefkada. There they occurred simultaneously with ephyrae and young medusae. Adult medusae were also observed in September 2006 in the harbour of Igoumenitsa. In a laboratory maintenance trial, collected ephyrae grew to an umbrella diameter of 4.6 cm in 60 days. This is the first record of a reproducing population of tropical medusae in the Central Mediterranean Sea.

The invasive ctenophore, Mnemiopsis leidyi, was recently observed for the first time in Danish waters where it was widely distributed during the summer of 2007. In certain areas, including Limfjorden, it exhibited mass occurrence. In this study, we assess the abundance of M. leidyi in Limfjorden in the late summer of 2007 and give a preliminary evaluation of the predation effects of this ctenophore. On two cruises in August and September, M. leidyi was found in every net sample from 9 locations in Limfjorden. The population densities were high, up to more than 800 individuals m^-3 in the innermost part, but body lengths were small (5 to 15 mm). The bio-volumes were very high (100 and 300 ml m^-3) in the central parts of Limfjorden and are even greater than those from the Black Sea, where the greatest mean bio-volume was about 184 ml m^-3 in the autumn of 1989 when the zooplankton and fish stocks collapsed. The possible ecological consequences of the mass occurrence of this ctenophore are discussed.

A few specimens and egg capsules of the American oyster drill, Urosalpinx cinerea, have been found in the Oosterschelde, an area of shellfish culture in The Netherlands. Probably U. cinerea was introduced with imported shellfish from south-east England. It is expected that the oyster drill will establish itself firmly in The Netherlands. The ban on anti-fouling paints containing tributyltin has increased the risk of introduction of oyster drills to new areas in Europe.

Long-term, regular studies of coastal plankton communities were resumed in 2002, based on bi-weekly plankton casts at three stations located within and adjacent to Sevastopol Bay, Crimea, northern Black Sea. In October 2005 two adult females of Oithona brevicornis were initially discovered in a sample taken during a routine plankton survey. Within one month after this discovery O. brevicornis began to appear in the samples regularly. In November 2005 the total abundance of O. brevicornis exceeded 1000 ind./m³ in the central part of the Bay. From April 2006, O. brevicornis disappeared completely from net catches and was absent until July 2006 when this species reappeared. The peak abundance of this species – 42667 ind./m³ – was recorded at the central station within the Bay at the end of October 2006. The possible route of invasion and the seasonal dynamics of this new copepod species in the Black Sea coastal region are discussed.

The amphipod Caprella mutica is one of the most rapidly invading species in Europe and has extended its range throughout North Sea and Celtic Sea coasts and the English Channel in less than fourteen years. It was first described from sub-boreal areas of north-east Asia in 1935 and has since spread to both northern and southern hemispheres. The first European record was from The Netherlands in 1994. Since then it has spread within the North Sea and later to the west coast of Scotland and to Ireland. C. mutica is frequently associated with man-made structures and is found in abundance on boat hulls, navigation/ offshore buoys, floating pontoons and aquaculture infrastructure. It is highly likely that its dispersal is associated with vessel movements whilst attached to hull fouling. This species is expected to colonise the west coasts of France and Spain and offshore islands in the north-east Atlantic.

Osmoregulation efficiency greatly determines the settling of aquatic invasive species in a new environment. The successful establishment of invasive cladoceran Cercopagis pengoi in the North American Great Lakes raises the question about a possible invasion of this species from the Baltic Sea to freshwater bodies like the Finnish Lake District using canals and rivers as invasion corridors. However, major ion concentrations (Na⁺, Ca²⁺, Mg²⁺, Cl^-, SO4^2-) in Finnish and in many other North European fresh waters are much lower than those in the Great Lakes. In our study we compared the survival of nonacclimated C. pengoi in waters collected from the Baltic Sea and Lake Saimaa as well as in experimentally ion-enriched Lake Saimaa water, which resembles the ion characteristics of the waters of the Great Lakes colonized by C. pengoi. In short-term experiments (24 and 56 h), the survival of C. pengoi was poor in Lake Saimaa water compared with Baltic Sea or enriched Lake Saimaa water. LT₅₀ was lowest in Lake Saimaa water (9.51 h), followed by Baltic Sea water (18.4 h) and enriched Lake Saimaa water (20.5 h). Furthermore, single ion additions improved survival in Lake Saimaa water. According to this preliminary study, imminent invasion of C. pengoi to freshwater systems with low concentrations of major ions appears unlikely. However, the impact of adaptation on the survival and dispersion of C. pengoi remains open.

The red alga Antithamnion nipponicum was discovered on the west coast of Norway, south of Bergen in 2007. From its native range in Japan and Korea the alga was first introduced to the Mediterranean Sea in 1988. Except for a possible report from the Azores (as A. pectinatum) there are no published records from European Atlantic coasts. The introduction to Norway most likely occurred via fouling on ship hulls, or by ballast water. Vegetative and tetrasporangium-bearing plants were found, and the specimens conform to the detailed description recently published by Cho et al. (2005), based on material from Pacific and Atlantic coasts of North America where the alga is also a recent introduction.

The red alga Asparagopsis taxiformis, a seaweed that is possibly introduced in the Mediterranean Sea, is recorded for the first time in Greece. Although no invasive behaviour was observed at any studied site, its spread seems to have been progressive during the last couple of years. However, the origin of the population on the Greek coasts remains uncertain.

More than 30 alien foraminifera species have been reported from the Levantine Basin. The most abundant of them is the Indo-Pacific originated Amphistegina lobifera Larsen, which is the dominant foraminifera species on the coasts of Israel and southwestern coasts of Turkey. It is widely distributed in the Eastern Mediterranean, Aegean Sea and even recorded in the Sea of Marmara. The westernmost limits of its distribution extend to Libya and Tunisia. This study constitutes the first record of Amphistegina lobifera Larsen from the Maltese Islands in June 2006.

The Asian ascidian Styela clava was recorded for the first time from the island of Helgoland-Düne, Germany, in July 2007. This is the first record of this species from the only two offshore islands in the SE North Sea.

The invasive ctenophore Mnemiopsis leidyi is expanding its range in the Baltic Sea. It was observed in the Landsort Deep in March 2007 and in the western part of the Gulf of Finland, Åland and Bothnian Seas in August 2007. In September the abundances were several times higher in the Gulf of Finland and the Åland Sea than in August, maximum abundances being 694 ind m^-2, and densities 24 ind m^-3. In December M. leidyi was observed also in the eastern Gulf of Finland at low abundances. Eggs and newly hatched larvae as well as juvenile stages were observed during autumn, indicating efficient reproduction and establishment of the species in the northern Baltic Sea.

We report the discovery of Mnemiopsis leidyi A. Agassiz, 1865 in the Gulf of Gdańsk (southern Baltic Sea, Poland) in October 2007. During the first month of observations the species was found in many areas of the Gulf of Gdańsk, from the surface to a depth of 42 m. The length of individual M. leidyi varied from 1.8 to 8.0 cm.

Blooms of Mnemiopsis leidyi observed along the coast of The Netherlands in late 2006 have made the spreading of this invasive ctenophore to neighboring waters a topic of major concern. Here we report on recent occurrences of M. leidyi in Danish waters, observed partly by ourselves and other biologists, partly by beach guests, boat owners and amateur divers. The earliest record of M. leidyi is from August 2005 and the early summer of 2006, and in 2007, the earliest records are from February and March, from the northern Little Belt and Kerteminde Bay. In the period April to June, the density of M. leidyi remained very low in the Great Belt, but numerous reports indicate that the ctenophore in July to September was widely distributed in all inner Danish waters, and "mass occurrences" have been reported from certain areas.

A specimen of the invasive mytilid mussel Brachidontes pharaonis (Fischer P., 1870) was collected on 18 April 2007 in Karaburun Peninsula, İzmir. This record represents the northernmost occurrence of the species along the Aegean coast of Turkey. Information on the distribution of the species along the Mediterranean coast of Turkey is provided.

The non-native estuarine shrimp, Palaemon longirostris H. Milne Edwards, 1837, is reported for the first time on the Sinop Peninsula coast (southern Black Sea). The species is previously known to occur in the northeastern Atlantic Ocean and the eastern Mediterranean including the Aegean Sea and the Sea of Marmara.

The first Mediterranean record of the Indo-Pacific humpnose big-eye bream, Monotaxis grandoculis (Forsskål, 1775), was recently reported at Antalya Bay, Turkey. It is suggested that this fish had entered the Mediterranean through the Suez Canal.

The Ponto-Caspian invasive gobiid fish Proterorhinus marmoratus (tubenose goby) is recorded for the first time from the Baltic Sea area: single specimens were found in the Neva River on 15 August 2006 and the eastern part of the Gulf of Finland on 23 July 2007. This fish is at the initial stage of a Baltic Sea invasion.