The freshwater red algal form taxon, Chantransia macrospora Wood, was recently collected at an artificial reservoir pond in Okinawa, Japan. This species is chiefly characterized by a bluish-green thallus and erect filaments irregularly branched with cylindrical to tapered cells and monosporangia on lateral branchlets. Our culture study confirmed that C. macrospora from Okinawa was the ‘chantransia’ sporophyte of Batrachospermum species. The rbcL sequence of C. macrospora from Okinawa was identical to isolate FG15 of this species from French Guiana in South America. The sporophyte Chantransia macrospora as well as the gametophyte B. macrospora Montagne are distributed in North and South America. However, there have been no records of either C. macrospora or B. macrosporum in Japan or in eastern Asia. Therefore, C. macrospora specimens originally from South America may have been introduced to Okinawa, Japan, through the vector such as ornamental macrophytes.

Invasive tunicates are creating costly fouling problems to the mussel aquaculture industry in many regions including Prince Edward Island, Canada. These invasive tunicates are also posing a threat to the ecosystem integrity of native species. There are currently four invasive tunicate species present in waters surrounding Prince Edward Island including: Ciona intestinalis, Styela clava, Botryllus schlosseri, and Botrylloides violaceus. Current monitoring practices for the presence of these species in PEI are conducted by costly and time consuming recruitment plates or via microscopy surveys for egg and larval stages using dissecting microscopes. However, these methods are inadequate for early detection. Recruitment plates only allow for the detection of tunicates once they have already established, and microscopic methods can be inaccurate since it is difficult to distinguish between eggs and larvae of different species of tunicate. In this study, we propose polymerase chain reaction (PCR) based detection as a means to overcome the limitations of current monitoring practices in water samples. For this purpose, oligonucleotide primers were generated to enable the rapid analysis of samples for the presence of invasive tunicates by PCR. Primers were designed from 18S rDNA and COI gene sequences specific to each species and were evaluated for efficacy, specificity, and sensitivity in detecting target tunicate species. Through efficient detection methods and careful monitoring it is hoped that further invasions of these tunicate species throughout Prince Edward Island waters can be prevented or managed in their early stage.

The colonial ascidian Didemnum vexillum was observed overgrowing fouling organisms present on structures within Holyhead Marina in North Wales in September 2008. Despite the examination of 9 other marinas in Wales during December 2008 and February 2009 no further populations were found. During December 2008 the extent of D. vexillum within Holyhead Marina and the surrounding harbour area was examined by diving. D. vexillum formed dispersed colonies throughout the marina, with <1% to 10% cover, but was not observed at any location within Holyhead harbour outside of the marina. Levels of infestation appeared to be low indicating a recent possible arrival. D. vexillum was found on the hulls of two vessels berthed within Holyhead marina but these vessels were long-term residents and not believed to be the source of infection. However, it is expected that hull fouling on recreational boats may become important vectors in the dispersal of D. vexillum to other regions around Britain. Although the species has been known in northern Europe since the 1990s, this is the first recorded established population of D. vexillum in Great Britain. In September 2008 a single colony of D. vexillum was collected in a marina in Plymouth and a colony, appearing to be D. vexillum, was photographed at the Darthaven Marina in 2005. The species was confirmed at this site in July 2009 by the collection of a single colony.

The first records of Styela clava are reported from the northern coasts of Ireland from two sheltered inlets in 2008. On the south coast, high densities were found associated with mussel longlines in a shallow bay and remained abundant in 2009. There is a potential for expansion of the species that may impact upon aquaculture installations in Irish shallow waters. The distribution of the species in Ireland is reviewed.

The first specimens of the Asian prawn Palaemon macrodactylus Rathbun, 1902, including ovigerous females, were identified in estuarine water bodies along the Romanian coast during early September 2009, in large numbers compared to the native prawns Palaemon elegans Rathke, 1837 and Palaemon adspersus Rathke, 1837. Examination of archived samples backdated the first occurrence of P. macrodactylus in the Black Sea to 2002. The supposed vector of introduction is via ballast water, from ships travelling from Rotterdam. Native to the seas of Japan and Korea, P. macrodactylus was first introduced in California in the 1950s, Australia in the 1970s and later to Britain, parts of continental Europe and Argentina. The Asian prawn already has well-established populations in the Romanian Black Sea and, taking into consideration the invasion record and the ecology of this species, it is very likely that it will successfully invade the whole of the Black and Azov Seas and the adjacent estuaries, deltas and limans.

This paper reports on the state of the Asian shore crab Hemigrapsus sanguineus (de Haan, 1835) population around the Cotentin Peninsula (Normandy, France) for 2009. As in 2008, the year of the first survey, the northern and eastern Cotentin coasts remain the most densely colonised. On the western shore, H. sanguineus remains rare, except in two sites not surveyed in 2008. In the east most colonised sites, Gatteville-Phare and La Hougue, the populations for both years indicate a rapid increase of abundance: maximum density > 50 ind.m^-2 in 2009 compared to 10 ind.m^-2 in 2008. This observation probably demonstrates that the species' current significant increase is comparable to that of an invasive species. A second species of Asian shore crab Hemigrapsus takanoi Asakura & Watanabe, 2005 was only present on one eastern site off Saint-Vaast-La-Houge, but remains isolated.

Exuviae of Chinese mitten crab were collected in the Saw Kill, a small tributary to the fresh-tidal Hudson River, in summer and early fall 2008. Most exuviae were found in July when water temperatures exceeded 21ºC and numbers declined with subsequent decreasing water temperatures. Sizes ranged from 12 to 45 mm CW and all were considered to be in their second summer (1+). Very small exuviae (≤ 15 mm CW) were present from early June through mid-August indicating recruitment to the Saw Kill all summer. Live mitten crabs were difficult to collect and therefore data from exuviae were useful in observing the early stage of this invasion.

Establishment success of invasive species depends largely on the size of the initial source population because small populations are more likely to fail due to stochastic or inverse density-dependent Allee effects. However, there are difficulties involved in using propagule pressure as an explanatory variable to account for establishment success because records concerning the size of initial source populations are typically (i) non-existent, (ii) only rough estimates and/or (iii) based on indirect measurements. The focus of this study was the establishment success of a deliberately introduced non-native salmonid, Salvelinus fontinalis as a function of actual site-specific propagule pressure. Additionally, we investigated whether newly released fish located suitable habitat patches, potentially facilitating the spread of the invader across Finnish stream systems. We found that the propagule pressure leading to highly successful establishment amounted to approximately 8000 released individuals. Additionally we also noted that one fourth of the newly introduced fish rapidly located suitable habitat patches (small tributaries) during initial dispersal, thus potentially increasing establishment success and the spread of the invader. The results suggest that by considering both propagule pressure and initial dispersal it will be possible to understand the latter stages of the invasion process, eventually leading to an improved capability in predicting successful invaders and sites that will be invaded.

We documented the abundance and habitat association of the native virile crayfish [ (Hagen, 1870)] and two invasive species, the rusty crayfish [O. rusticus (Girard, 1852)] and the papershell crayfish [O. immunis (Hagen, 1870)] in a 38 km² area in the Lake of the Woods (LOW; Canada). From 20 June to 1 September in 2006, traplines were set at 376 sites for approximately 24 hours. A total of 9833 crayfish were captured, of which 68% were O. virilis, 23% were O. rusticus, and 9% were O. immunis. The mean catch per unit effort (CPUE) was 4.4 crayfish per trap with a maximum of 29. At least one invasion front of O. rusticus was detected, where its CPUE decreased sharply from a mean of 1.3 to 0.03. The mean CPUE of both O. virilis and O. immunis was significantly higher outside than within the front. For the entire catch, CPUE values of all three species were negatively correlated.
Water depth (0.5-12 m) was significantly related to crayfish abundance, positively for O. virilis and negatively for O. rusticus and O. immunis. The distribution and abundance of the two invasive species on islands and adjacent mainland sites indicated that water depths near and deeper than the thermocline limit the colonisation of islands by O. rusticus and, particularly, O. immunis, but that islands surrounded by shallower water may serve as shortcuts in crayfish expansion circumventing convoluted shorelines. Mean CPUE of all three crayfish species differed between bottom substrates, being highest on mainly rocky substrates for O. virilis and O. rusticus, and on organic and inorganic fines for O. immunis. Mean CPUE of O. virilis near macrophytes was similar to that in areas free of aquatic plants; CPUE near macrophytes was significantly lower for O. rusticus and significantly higher for O. immunis.
In conjunction with crayfish captures during lake-wide fish surveys between 1973 and 2006, we show that by 2006 O. rusticus has spread into most parts of LOW since its first record from Long Bay on the east side of the lake in 1963, expanding its distribution by an average of 2.1 km per year. Our results further indicate that O. immunis is more widespread and more abundant in LOW than previously assumed.

Despite the continued arrival and impacts of non-native aquatic species in the Great Lakes, there is as yet no comprehensive early-detection monitoring program for them. As a step towards implementing such a program, we evaluated strategies for efficient non-native species monitoring based on the ability to detect a diverse set of benthos and fish species currently present in a heavily invaded, spatially complex Great Lakes subsystem. Taxa accumulation analyses confirmed that reliable detection of rare species requires substantial sampling effort but also that there is potential for exploiting patchiness in distributions to increase efficiency. While non-native species monitoring warrants generally comprehensive spatial coverage, it may be possible to identify areas where such taxa are broadly most prevalent (e.g., the lower reaches of our study system) as a way to focus effort. On a finer scale, richness of non-native taxa may vary substantially among stations in close proximity – which in this system was driven by habitat variability rather than distance from potential introduction points. Microhabitats that differ in physical attributes are also likely to differ in species composition and richness. Randomization analyses indicated that some monitoring effort should be directed towards all distinct habitats but that detection rates are maximized by biasing effort towards those habitats or gear yielding the most total, non-native, or rare taxa. For benthic invertebrates, shallow structurally complex (vegetated) habitats yielded the most taxa but shallow open and deep habitats also contributed unique taxa. For fish, fyke-net stations (shallowest habitats) yielded the most taxa, but electrofishing (intermediate-depth) and trawling (deepest) also contributed unique taxa. Our approach to identifying relevant sampling strata and exploiting difference among them to increase the efficiency of early-detection monitoring is applicable to a broad variety of systems.

The invasive bryozoan Zoobotryon verticillatum Delle Chiaje, 1822 is recorded from Madeira for the first time. Apparently it has been growing on the floating pontoons of Quinta do Lorde harbor, at the southeastern coast of Madeira Island, for some time already.

The comb jelly Mnemiopsis leidyi was first reported in July 2009 along the Spanish coast of the NW Mediterranean Sea and occurred throughout the summer (last report 26 September 2009). Large numbers of the ctenophore were reported by many participants of the “Medusa Project”. The high concentrations of M. leidyi along the Spanish coast, together with its blooms earlier this year in Israel, suggests establishment in the Mediterranean Sea. This is of great concern because of the well-known effects of M. leidyi on marine ecosystems and the consequences for commercial fisheries.

The gelatinous macroplankters Mnemiopsis leidyi and Phyllorhiza punctata are recorded for the first time from the Italian coasts of the Western Mediterranean. In the framework of the CIESM Jellywatch campaign in the summer of 2009, M. leidyi was recorded from the Ligurian, Tyrrhenian, and Ionian Seas, including swarming episodes that, together with those reported from Spain in the same period, suggest a great success of the species in the Western Mediterranean. A single specimen of P. punctata has been recorded from Sardinia. These species do not sting or harm humans and no impact on tourism is expected, but they might harm fisheries by predating on fish eggs and larvae and their prey, zooplankton. The large distribution area of M. leidyi suggests the species invaded the Western Mediterranean during the summer of 2009, but its establishment is still uncertain, since the populations might not withstand winter conditions. The isolated record of P. punctata just indicates that it can reach this part of the Mediterranean.

This paper aims to set the record straight regarding the first observations of Corbicula fluminea (Müller, 1775) in the Guadiana River Basin. According to the available data, C. fluminea was first observed in 1988 and not in 2006 as suggested by Pérez-Bote and Fernandéz (2008). The first observations of C. fluminea in the Guadiana estuary were reported in 2000. In 2003, C. fluminea was already well established in the estuary and in many rivers and streams. C. fluminea is likely to expand its current biogeographic distribution in Portugal, since suitable lentic habitats for colonization will be created by the implementation of the “National program of dams with high hydraulic potential”, which should be concluded by 2016.

The first record of Sinanodonta woodiana (Lea, 1834) (Bivalvia: Unionidae) in Lake Garda, the largest Italian lake located in the Southern Alps is reported. Empty shells of this alien bivalve, also known as the Chinese pond mussel, were observed in February 2009 along the southeastern shore.

Orchestia cavimana, a semiterrestrial amphipod of presumably Mediterranean origin was found for the first time in a freshwater habitat in Poland in October 2009, in the main Vistula channel at Świbno. Most probably the species reached this locality from the nearby Baltic coast by natural spread up the river. Taking into account its high abundance at the site and presence of immature individuals, the species has probably established a permanent population in this new habitat in Poland.

The Ponto-Caspian amphipod Echinogammarus trichiatus (=Chaetogammarus trichiatus) was found for the first time in Slovakia (22 August 2007, near Bratislava) and in Hungary (15 September 2009, near Rajka). This range expansion is probably a result of a recent downstream spread of the Upper-Danubian populations. Our records indicate that the species can inhabit artificial rip-raps as well as near-natural gravel banks, and co-occurs with its relatives already present. Suitable habitats can be found all along the Middle-Danube, so further spread of the species is anticipated.

During a zooplankton monitoring program in the Rhine catchment (Southern Germany) during the 2006 sampling year, we recorded the mysid Hemimysis anomala in an oligotrophic gravel pit lake. The crustacean and rotifer abundance in the lake was low; maximum density was 28 and 145 ind. L^-1, respectively. Crustaceans were dominated by copepods, which constituted 90-100% of the zooplankton community. Cladocerans were represented only by Diaphanosoma brachyurum. Rotifers were dominated by Polyarthra spp. for most part of the year. We suggest that the reason for the lack of cladocerans (except Diaphanosmoma) could be competition and/or predation by H. anomala. That D. brachyurum could persist in the presence of Hemimysis may be a result of spatial segregation. Possibly, due to differences in thermal preferences, H. anomala avoids the warm epilimnion of the lake in summer while Diaphanosoma may prefer it.

The Erythrean stomatopod Clorida albolitura is reported herein for the first time from the Bay of Iskenderun on the Mediterranean coast of Turkey. Additional records from locations off the southern coast of Israel attest to the presence of a rapidly growing population of this alien species in the Mediterranean Sea.

This short note reports on the first European records of Sinelobus stanfordi (Crustacea: Tanaidacea: Tanaidae). The species has been recorded from five different water bodies in the Dutch coastal area and in the docks of the Belgian harbour of Antwerp. S. stanfordi was until now not known to inhabit (North-) European coasts and estuaries. It is thus very likely that its origin is non-indigenous.

A specimen of Carupa tenuipes Dana, 1851 (Crustacea: Brachyura: Portunidae) from the eastern coastline of Rhodos Island is reported from under stones of a rocky substrate with low vegetation coverage at 0.5 m. Carupa tenuipes is considered to be a well established alien decapod species in the Eastern Mediterranean.

On August 2008, a single individual of the red king crab Paralithodes camtschaticus, a boreal species indigenous to the North Pacific, was caught by a gill net in the Ionian Sea, Central Mediterranean. The crab weighed 4 kg and it is estimated it was ten years old. Transport in ballast water seems the most likely way of introduction. If true, the implication is that this cold-water species is capable of surviving and growing to adulthood in a warm-temperate sea.

The North American black bullhead Ameiurus melas has been recorded for the first time in the Guadalquivir Estuary. The abundance of A. melas was monitored and quantified after first detection (February, 2007), with captures in two consecutive surveys (from October to December for 2007 and 2008) using nylon fyke nets. Catch per unit effort (CPUE) showed a rapid increase from 0.11 individuals per net in 2007 to 0.47 ind net^-1 in 2008. Additionally, A. melas specimens collected in the 2008 survey (n = 1563), were measured (LT) and weighed to study the population structure and allometric growth relationship. The rapid increase in abundance of A. melas, together with the cohort analysis of individuals collected in the 2008 survey, suggest that incipient reproduction of black bullhead is already occurring. The invasion of A. melas constitutes a new threat to biodiversity in the Guadalquivir Estuary and connected natural parks and reserves (e.g., Doñana National Park). It also presents potential economic damage to fisheries and aquaculture fish-farms.