This is the first attempt to outline the occurrence of selected invasive alien vertebrates in Greece, since up to now, there are no “official” or scientific reports except from sporadic sightings and anecdotal stories. Records on the occurrence of: Lithobates catesbeianus, Trachemys scripta (T. s. elegans and T. s. scripta), Neovison vison, Myocastor coypus, Nyctereutes procyonoides and Ondatra zibethicus were requested through a pan-Hellenic survey. According to the results, the coypu (Myocastor coypus) appears to be the most widely distributed of all species, having conquered practically all wetlands of Western and Central Greece with populations exceeding, in most cases, 20 individuals each. On the contrary, there is merely one unconfirmed record of the raccoon dog (Nyctereutes procyonoides) while there were no sightings at all for the muskrat (Ondatra zibethicus). The American mink (Neovison vison) was recorded in the northwestern part of Greece. Regarding the alien herpetofauna, the bullfrog (Lithobates catesbeianus) seems to be still confined in Crete where it was originally introduced, while the red-eared slider (Trachemys scripta) appears mostly in Crete, Attiki prefecture, and a few more places, showing most probably an underestimated distribution.

Snakes have become successful invaders in a wide variety of ecosystems worldwide. In southern Florida, USA, the Burmese python (Python molurus bivittatus) has become established across thousands of square kilometers including all of Everglades National Park (ENP). Both experimental and correlative data have supported a relationship between Burmese python predation and declines or extirpations of mid- to large-sized mammals in ENP. In June 2013 a large python (4.32 m snout-vent length, 48.3 kg) was captured and removed from the park. Subsequent necropsy revealed a massive amount of fecal matter (79 cm in length, 6.5 kg) within the snake’s large intestine. A comparative examination of bone, teeth, and hooves extracted from the fecal contents revealed that this snake consumed three white-tailed deer (Odocoileus virginianus). This is the first report of an invasive Burmese python containing the remains of multiple white-tailed deer in its gut. Because the largest snakes native to southern Florida are not capable of consuming even mid-sized mammals, pythons likely represent a novel predatory threat to white-tailed deer in these habitats. This work highlights the potential impact of this large-bodied invasive snake and supports the need for more work on invasive predator-native prey relationships.

Marine fouling communities on artificial structures are invasion hotspots for non-indigenous species (NIS). Yet, little is known about NIS in fouling communities of British Columbia (BC), Canada. To determine NIS identity and richness in BC fouling communities, we deployed settlement plates at 108 sites along the coast of BC between 2006 and 2012. Of the 295 invertebrate taxa identified to species, 20 were NIS while an additional 14 were cryptogenic, including several global invaders. This study documents the range expansion of tunicates Botrylloides violaceus Oka, 1927 and Botryllus schlosseri (Pallas, 1766), including the first known records on Haida Gwaii. NIS were detected within each of the six distinct geographic regions with the southern, more populated regions of BC (Straits of Georgia and Juan De Fuca) having the highest NIS richness and frequency of occurrence compared to the less populated northern regions. This study provides a contemporary baseline of invertebrate NIS identity and richness in fouling communities that will allow comparisons through time and a means to focus research and prioritize management efforts.

Opuntioid cacti have caused some of the most damaging plant invasions globally. While many of these invaders were introduced for ornamental and some agriculture use, there are an increasing number of records of invasive ornamental species. Here we report the first detailed invasion by Opuntia pubescens and investigate the potential for eradicating the species from South Africa. We found the species only at one location (Pretoria National Botanical Gardens) where the population was approximately 5023 plants over the undeveloped area of 3.66 ha. The plant was not found during surveys of neighbouring natural areas. We believe it was introduced to staff gardens as an ornamental plant, but we have not found it on sale in nurseries nor mentioned in historical literature. However, as the species was initially confused with O. aurantiaca, surveys were conducted in the neighbouring hills and Gauteng province for all known O. aurantiaca infested farms. Initial efforts on surveying the Limpopo, KwaZulu-Natal and Eastern Cape provinces with the assistance of Department of Agriculture, Forestry and Fisheries Land Use and Soil Management Resource Auditors have been initiated, but more work still needs to be done. Therefore, while preliminary control efforts in the garden looking promising; it is not clear whether nation-wide eradication is feasible. The Australian Weed Risk Assessment was used to collate information and determine the invasive potential of O. pubescens in South Africa. This method has been used worldwide and within the programme to determine risk potential of invasive species in the country. To determine the potential distribution of O. pubescens we developed a species distribution model using MaxEnt 3.3.3e based on native and non-native range. This study highlights the need to discourage the use of Opuntioid cacti as ornamental species due to their invasiveness, even if they are not yet known to be invasive.

Limnobium laevigatum (Hydrocharitaceae) is a freshwater plant indigenous to Central and South America, which has become naturalized and invasive in parts of North America, Asia and Australia and has been detected in Southern Africa. Populations have been found in Zimbabwe and Zambia over the last eleven years and we warn of its likely spread to other parts of Africa and the likelihood of it becoming invasive in tropical Africa.

We report a sizeable population of Carolina fanwort Cabomba caroliniana from Belgium. The new population was discovered in June 2013 and represents the only occurrence in the Atlantic region of this country. A previous record dates back to 1998 but by 2006 this population was eliminated unintentionally by dredging works. Cabomba caroliniana is expected to become a regulated invasive alien species of EU concern, in which case it will need to be eradicated. We briefly describe the site conditions, discuss possible measures for eradication and present a decision support scheme.

Gonionemus vertens A. Agassiz, 1862 is a small hydrozoan native to the Pacific Ocean. It has become established in the northern and southern Atlantic Ocean as well as the Mediterranean Sea. We report on the first occurrence of this species in estuaries in New Jersey, USA, and confirm species identification through molecular sequence analysis. Given the large number of individuals collected, we contend that this is a successful invasion into this region with established polyps. The remaining question is the vector and source of these newly established populations.

Since its first detection on the island of Ireland in April 2010, the invasive Asian clam Corbicula fluminea (Müller, 1774) has been confirmed present at five sites within the Republic of Ireland (RoI). In March 2016, specimens of C. fluminea were first discovered in Northern Ireland (NI) within the River Foyle, which delineates the border between RoI and NI. In a subsequent survey in June 2016 an established population was confirmed to be present within the River Foyle, where densities of clams attained 384 individuals m^-2. This highly invasive species can potentially represent a significant threat to freshwater environments. Therefore, increased biosecurity awareness and enforcement of existing legislation is needed to prevent further spread.

The North Pacific copepod Eurytemora pacifica Sato, 1913 was fortuitously found in a sea water tank of the Marinarium of Concarneau (Southern Brittany, France). The presence of ovigerous females in this tank as well as in some nearby ecosystems confirms the successful introduction of this species along the Atlantic coast of France. Morphology was examined using scanning electron microscopy and confirmed the species identity. The presence of two types of females resulting from cyclomorphosis was confirmed, as well as the production of two types of eggs. The French Atlantic coasts seem to be the only area in the world where the species has been reported as a non-indigenous species (NIS).

Silver carp (Hypophthalmichthys molitrix) and bighead carp (H. nobilis) are poised to invade the Laurentian Great Lakes. Zebra mussels (Dreissena polymorpha) and quagga mussels (D. rostriformis bugensis) have shifted nutrient pathways towards the benthos, partly through deposition of feces and rejected food particles called biodeposits. When biodeposit material was fed to bighead and silver carp, they fed on the material, but on average lost weight. Energy density between fed and unfed fish did not differ, but a few individual fish did gain weight on the biodeposits diet. Our results demonstrate that biodeposits might be considered a supplemental food for bigheaded carps.

Weakfish Cynoscion regalis (Bloch and Schneider, 1801) is a sciaenid fish native to the east coast of North America and has been recently collected in three areas of the Iberian Peninsula (Europe). We aimed to i) provide the first report of the presence of weakfish in Europe, ii) hypothesize the most likely introduction vector, iii) discuss the potential for ecological overlap between weakfish and meagre Argyrosomus regius (Asso, 1801), the native Sciaenidae species, and iv) highlight the importance of citizen science in the detection of non-native species. Weakfish were captured in the Sado estuary (July 2014), Gulf of Cadiz (November 2015) and the adjacent Guadiana estuary (June 2016), and in two Galician Rías (June 2016). Anglers reported that weakfish was present in the Sado estuary for “some” years, while their presence was only noticed recently in the other two areas. We hypothesize that ballast water was the introduction vector, that weakfish established a reproducing population in the non-native range, and that it dispersed from the Sado estuary, a central region of its current distribution range. The Sado estuary might have been the introduction area for weakfish via ballast water because there is a busy transoceanic commercial port in the estuary. Moreover, they are not used in European aquaculture facilities, nor in the aquarium trade. The collected specimens were ≤50 cm, with average lengths of 30 cm, which corresponds to a median age of 2 years and to individuals capable of reproducing. As a result, the year of introduction must be before 2012. Weakfish have a similar ecological niche to meagre, but the outcome of potential interactions is uncertain. Citizen science, especially the initiative of local fishermen, was critical to detect this non-native species.

The blue peacock cichlid Cichla piquiti is naturally found in the Tocantins-Araguaia river basins, but non-native populations are recorded in many reservoirs of Central and South Brazil. The present study provides, through both morphological and molecular analyses, the first record of the introduction of C. piquiti in a large and important river basin of south eastern Brazil. Morphological characteristics together with 35 cytb and 48 CR mtDNA sequences confirmed the putative sampled fish as C. piquiti, although hybridisation with C. kelberi (i.e. another Cichla species introduced at Lajes reservoir in the 1950s) cannot be entirely ruled out. Two stocking events were carried out in 2005 and 2010 by affiliated anglers of a local sportfishing club to introduce C. piquiti into Lajes, but only the latter resulted in established populations. Since C. piquiti can apparently achieve higher maximum size than C. kelberi, it is expected that the vulnerability of native fish to predation will be higher. In addition, there is the possibility of introgressive hybridisation between the two introduced Cichla species, which can obscure the recognition of successive events of introduction and potentially increase the impact on native fish assemblages. Finally, C. piquiti has the potential to become widespread, both by passive movement along interconnected systems within the Paraíba do Sul river basin, as well as through active transfer by local anglers to other more distant systems, following a similar trend to that which apparently occurred for C. kelberi. Therefore, the continuous assessment of peacock cichlid populations, together with further studies on the genetic characterization of C. piquiti, have great ecological relevance for the early detection of the spread of this invasive fish beyond the Paraíba do Sul river basin and throughout Brazilian territory.

Cichla kelberi, Cichla monoculus, and Cichla ocellaris are recognised as the most widespread introduced species of yellow peacock cichlids but most studies have failed to accurately identify these species in the invaded systems. The present study used molecular analysis to firstly confirm the introduction of C. monoculus in the Southeast Atlantic Hydrographic province, which encompasses areas from the three most populated Brazilian states. The cytochrome b sequences of 13 yellow peacock cichlids captured at two reservoirs from Paraíba do Sul river basin confirmed six of them as C. monoculus and seven as C. kelberi. Phylogenetic analysis revealed that the six C. monoculus caught in the Paraíba do Sul river clustered in a well-supported clade with other C. monoculus sequences available in GenBank. Some individuals showed divergences in colouration pattern from that of the original description of C. monoculus, suggesting that this species could be interbreeding with C. kelberi. Our findings stressed the applied importance of using molecular approaches to accurately detect invasive cryptic species and to track the spread of yellow peacock cichlids outside their native range.

We present the first record of the Chinese sleeper (Perccottus glenii), an Asian invasive fish species, in the Dnieper Estuary, southern Ukraine. This new locality is clearly distant from all previous known localities in the Dnieper drainage. As the new finding is situated close to a fish pond outlet, we suggest one possible route of introduction to be fish transfer for aquaculture.

The Seychelles dragonet Synchiropus sechellensis Regan, 1908 is reported for the fourth time from the Mediterranean and for the first time from Cyprus. This addition expands its distribution in the Mediterranean further from the Gulf of Antalya on the Turkish coast and the islands of Rhodes and Kastellorizo in Southeastern Aegean, placing a question mark whether this species was accidentally introduced in the Mediterranean as initially hypothesized, or it actively entered from the Indo-Pacific through the Suez Canal (Lessepsian immigration) and may have been overlooked in areas closer to the Canal. The basic measurements of the specimen caught in Cyprus, as well as an updated list of all Lessepsian fish species reported from Cyprus are given.

The silver-cheeked toadfish Lagocephalus sceleratus (Gmelin, 1789)—an invasive toxic species well established in the eastern Mediterranean—is rapidly expanding through the western Basin and a public campaign was set to inform Italian citizens on the risks associated with its consumption. Both news media and local communities responded rapidly to the initiative generating an increasing flow of information. On 15 April 2016, a new capture of this species (off Briatico, Calabria, Italy at 25 m of depth), was promptly reported to the authors, representing the first documented record of L. sceleratus from the Tyrrhenian Sea. On 7 June 2016, a second specimen was captured at Montebello Ionico in Calabria. This case of early detection is here presented as a successful example of interplay among citizens, researchers, and policy makers: a powerful approach for monitoring the spread of invasive species and reducing their potential impacts through increasing awareness.