Aquatic Invasions

Publications
Survey sites for Crepipatella dilatata in Northern Spain. Site 1 (O Grove Bay), Site 2 (Baia de Aldan), and Site 4 (Playa de Beluso) are reported locations of Crepipatella populations. Site 3 (42°20'09.11"N, 8°47'55.40"W), Site 5 (42°19'39.33"N, 8°47'32.15"W) and Site 6 (42°19'57.02"N, 8°46'20.48"W) were searched but no Crepipatella were found
(A) Living specimen and (B) dorsal and ventral views of a shells of Crepipatella dilatata collected from the shells of Mytilus galloprovincalis in September 2008. Scale bar = 1 cm 
Developmental stages of C. dilatata . (A) A cluster of egg capsules early in development. Scale bar = 4 mm. (B) Early intracapsular embryos showing the early development of the ridge that will become the velum surrounded by uncleaved nurse eggs. Scale bar = 600 μ m. (C) Fully developed embryos that have already lost the velum and are almost ready to hatch. Scale bar = 1 mm. (D) A recent hatchling. Scale bar = 400 μ m 
* Corresponding author Abstract Calyptraeid gastropods have been introduced frequently in bays and ports around the world, and have become rampantly invasive in several cases. Here we confirm the identification and establishment of a recently-detected population of Crepipatella in northern Spain. Because their shells do not have many diagnostic features, introductions of calyptraeids are often accompanied by confusion about the identity and therefore origin of the species in question. We use DNA sequence data and developmental observations to verify the species identity of this population as the South American species Crepipatella dilatata. The apparently rapid spread of this species, which lacks a larval stage, may be due to human action.
 
Katamysis warpachowskyi from Lake Constance. a: female; b: male; c: telson.  
Body length and brood size of Katamysis warpachowskyi in Lake Constance given as mean ± standard deviation if n > 3 or single measurements if n  3.
The mysid Katamysis warpachowskyi Sars, 1877 originated in the Ponto-Caspian region and the associated river systems. The first evidence of its transgression of the limits of the watersheds of its natural Ponto-Caspian origin was found when three individuals were recorded in October 2009 in eastern Lake Constance (Austria). In March 2010, K. warpachowskyi comprised 10% of the mysid assemblage and was mainly found in rocky habitats. On both sampling dates, breeding females were present. Before this invasion, Limnomysis benedeni Czerniavsky, 1882, was the only mysid in Lake Constance and is also distributed in the Rhine river system. Since the two mysids coexist in Lake Constance, K. warpachowskyi will likely become established in the lake and further expand into the main part of the Rhine. K. warpachowskyi is known as a benthic organism and feeds on detritus and small algae; therefore, the impact on the lake ecosystem should be weaker than that of pelagic mysids.
 
Distribution and relative abundance of Gracilaria vermiculophylla in Northern Europe. Invaded regions and the year of first observation was mapped using literature, monitoring data, queries and surveys. The circles sizes correspond roughly to the relative abundance of G. vermiculophylla at invaded regions. Subscripts indicate order of first observation, where 1 = Wadden Sea, Germany, 2 = Horsens Fjord, 3 = Swedish west coast, (circles size here based on 6 visited locations, cf. Nyberg 2006 for details), 4 = Vejle Fjord, 5 = Nibe and Gjøl Bredninger in Limfjorden, 6 = Kiel Bay, 7 = Wadden Sea, Denmark (Mandø), 8 = Holckenhavn Fjord, 9 = Øster Hurup Harbor, and 10 = Egense Harbor (Annex 2) 
Distribution and abundance of Gracilaria vermiculophylla in Horsens Fjord, July 2006. Circle sizes correlate with percentage cover. G. vermiculophylla was present at 20 out of 24 point-locations (black non-filled circles, black non-filled squares = 4 sampled locations without G. vermiculophylla), at 9 out of 9 'deep' dive transect-locations and at 3 out of 3 'shallow' video transectlocations (transect means shown, black filled circles). See Annex 3 for specific cover-values and corresponding geocoordinates.
Gracilaria vermiculophylla abundance versus depth in Horsens Fjord. Percent cover and depth was quantified from 36 locations visited in July 2006 (including overall mean values from 12 transects).
Attachment of Gracilaria vermiculophylla and other Gracilaria species. Attachment type was recorded from randomly selected thalli at Holckenhavn Fjord (Hol, N=32), 4 locations in Horsens Fjord (Hor 1-4, N=46, 48, 70, 42), Danish Wadden Sea (Wad1, N=72, western Mandø), German Wadden Sea (Wad2, pers. com. C. Buschman and G. Nehls), Kiel Bay (Kie, pers. com. D. Schories and F. Weinberger), 6 locations on the Swedish west coast around Göteborg, including Särö (Got1, N=25), Sandö (Got2, N=25), Stora Amundön (Got3, N=25), Askim (Got4, N=25), Rörvik (Got5, N=25), and Saltholmen (Got6, N=25), 2 location in Hog Island Bay, Virginia, USA (US1, US2, N=77, 137), 2 locations in Pauatahanui Inlet, New Zealand (G. chilensis, NZ1, NZ2, N=39, 41) and 2 locations in Swan River, Australia (G. comosa, AU1, AU2, N=86, 103). Attachment was classified into groups as shown on figure legend. Att. = Attached, Inc. = incorporated.
Performance of Gracilaria vermiculophylla . A 4- factorial experiment tested for interactive effects of salinity (S34, S17, S8.5, units = psu), light (L+ = 10% PAR reduction, L- = 90% PAR reduction), grazing (G+ = 1 Littorina littorea , G- = no grazer) and ‘number of fragments’ on biomass change (top) and fragmentation rate (bottom) over the entire experimental period (+SE). L. littorea could not be acclimatized to 8.5 psu and was therefore not added to this salinity level. Only significant effects are shown, and significant interactions are given graphical preference over single factor significant results (i.e. significant salinity × grazing, supersedes significant effects of salinity and grazing, cf. Annex 1) 
Gracilaria vermiculophylla, a red macroalga from the West Pacific, was discovered in western Germany (the Wadden Sea) in 2002 and has since also been observed in Sweden (from about 70 km south to about 80 km north of Göteborg), Denmark (Wadden Sea, Horsens Fjord, Limfjorden, Vejle Fjord, Holckenhavn Fjord, Øster Hurup Harbor) and eastern Germany (Kiel Bay). Today, less than 5 years following its first observation in the Wadden Sea the invader is common in many invaded regions, often being amongst the most abundant macroalgal species. G. vermiculophylla is successful in shallow protected soft-bottom estuaries and bays, typically in association with ubiquitous native invertebrates (lugworms, tube-building worms, mussels, cockles, snails). The invertebrates provide substratum for holdfast attachment and thalli incorporation, most likely increasing the stability of local G. vermiculophylla populations. We hypothesize that this substratum provision is highly important for its general invasion success. We also confirm that G. vermiculophylla can maintain growth at all salinities experienced along Danish coastlines (8.5-34 psu). In addition, laboratory experiments indicate that the ubiquitous grazer Littorina littorea has the potential to control G. vermiculophylla growth under specific environmental conditions, but also that L. littorea may facilitate small-scale dispersal within invaded locations, because grazing increases thalli fragmentation rates. Given its widespread distribution, rapid range expansion, and known ecological traits, G. vermiculophylla is clearly a permanent resident of northern European waters.
 
Study area of Denmark with its three main regions; Jutland, Zealand, and Fyn. Invertebrate and macroalgal samples were collected throughout Danish waters from east of Bornholm (Bh) to west of Jutland and included samples from both open waters and from all major estuaries, e.g. Limfjorden (Lf) and Ringkøbing fjord (Rf) 
Relative abundance of soft-bottom benthic invertebrate NIMS (divided by all individuals summed from all samples within a specific time period). Only significant correlation results are included on graphs (p > 0.32 for rest of tests, n = 22)
Relative abundance of hard-bottom benthic macroalgal NIMS (divided by all cover values summed from all samples within a specific time period, n = 15). Tests were not performed on the very recent NIMS (Gracilaria vermiculophylla, Heterosiphonia japonica, Neosiphonia harveyi), only significant and near-significant correlation results are included on graphs (p > 0.16 for rest of tests, n = 15)
Non-indigenous marine species (NIMS) have only recently caught general interest in Denmark, and baseline studies are needed to identify what species are of particular importance in order to prioritize management and research efforts. We used large data sets compiled in monitoring databases to quantify annual nation-wide changes in abundance of non-indigenous soft-bottom invertebrates (from grab samples) and hard-bottom macroalgae (from diver based percent cover values) in Denmark. Based on criteria of being either abundant (constituting >1% of the entire Danish assemblages) or increasing in abundance, NIMS of particular interest were found to be Mya arenaria and Bonemaissonia hamifera (abundant), Crepidula fornicata, Ensis americanus, Neanthes succinea (a cryptogenic species), Marenzelleria spp. (increasing), and Sargassum muticum (abundant and increasing). In addition, new and/or warm-water eurohaline NIMS such as Gracilaria vermiculophylla and Crassostrea gigas, should be given attention as these species are expected to increase in the future. Finally, species not included in existing monitoring programs (hard-bottom estuarine invertebrates, fish, parasites, highly mobile species) should also be targeted in future sampling programs.
 
Sampling sites in Upper Lake Constance. Routine sampling site for macrozoobenthos and benthivorous fish sampled in 2000-2004 (arrow), and six additional sites sampled in 2005 and 2006 (triangles) 
Abundance of G. roeseli and D. villosus (individuals ⋅ m -2 ) at two sampling sites in Upper Lake Constance assessed at 40 cm water depth before and after D. villosus became established at these sites
The Ponto-Caspian amphipod Dikerogammarus villosus (Sowinski) invaded Lake Constance, Central Europe (47°39'N, 9°18'E,)in 2002 and within four years had colonized the entire littoral zone of the upper lake basin, replacing the formerly dominantspecies Gammarus roeseli Gervais. Fifteen fish species were sampled from six littoral sites in the upper lake basin in 2005 and 2006, and their stomach contents were compared with samples taken prior to the replacement of G. roeseli by D. villosus. Three zoobenthivorous fish species (European eel Anguilla anguilla (L.), Eurasian perch Perca fluviatilis L., and burbot Lota lota (L.)), which had regularly consumed G. roeseli, included D. villosus immediately into their diet in similar proportions. Shifts in amphipod consumption have thus not been detected, whereas effects of the invasive amphipod on the macrozoobenthos community, which on their part might affect the food base of littoral fish, require detailed study.
 
Location of the recent non-indigenous ascidians in the Mediterranean. The families are indicated by symbols: ● Polycitoridae ▲ Perophoridae o Corellidae ■ Ascidiidae x Styelidae ♦ Pyuridae  
Special issue “Proceedings of the 2nd International Invasive Sea Squirt Conference” (October 2-4, 2007, Prince Edward Island, Canada) Andrea Locke and Mary Carman (Guest Editors). A revision of the non-indigenous ascidians in the Mediterranean Sea has been carried out, from published and unpublished records. The records considered include the last 50 years, which encompasses the period after the Pérès inventory (in 1958). Our aim is to analyze the ancient and recent records with comments about their validity and possible introduction vectors.
 
The 100 th Meridian Initiative was developed to help prevent the spread of aquatic nuisance species (ANS) through boater education and research on boater movement patterns and behaviors. Surveys employing these elements were conducted at Lake Mead National Recreation Area (LMNRA) in 2002-2003 before the discovery of the quagga mussel (Dreissena rostiformis bugensis Andrusov 1897) and in 2007-2008 after an established population of quagga mussels was found in the Lake. Boaters were asked questions in a personal interview or a mail-in survey regarding what body of water they had previously launched their watercraft in, where they were planning to launch next, if they cleaned their watercraft between each launch, and if they were aware of quagga mussels or other ANS. Results from the personal interviews and mail-in surveys indicated a significant increase in mussel awareness between the pre- and post- mussel invasion groups. Cleaning habits between the study periods for both interviews and mail-in surveys did not differ significantly. Boat trailer states of registration were also documented in both study periods in the parking lots of LMNRA. In 2002-2003, 0.6% of the trailers documented were from states with known zebra or quagga mussel populations, whereas in 2007-2008, 98.2% of states documented had known zebra or quagga mussel populations. Increased boater awareness will help prevent the spread of aquatic invasive species and the 100 th Meridian Initiative is a helpful way to educate boaters and collect relevant data on future mussel invasions. The preservation of natural waters is vital for the conservation of native species and the prevention of zebra and quagga mussel invasions will assist in this preservation. Further efforts should be directed toward educating boaters on effective cleaning methods.
 
The study site at Agger Tange in the western part of the Limfjord, Denmark. The bivalve bed was divided into three zones: Southern (S), Middle (M), and Northern (N) Zone.  
Location of the sample points on the bivalve bed (n = 155). The cells in the grid are 40 × 40 m.  
Orthophotos depicting the extent of the bivalve bed from 1999 to 2010. In all orthophotos, it is possible to distinguish the bivalve bed from the surrounding sand and mud flats, thus they were included in the analysis of spatial development of the bivalve bed (Danish Digital Orthophoto, consultancy firm COWI, Denmark). The resolution of the orthophotos ranged from 13 × 13 cm to 40 × 40 cm.
The invasive Pacific oyster, Crassostrea gigas Thunberg, 1793 was introduced in Denmark for aquaculture in the 1970s. Presently, feral populations are found in many parts of the country, with the largest populations established on existing beds of blue mussel, Mytilus edulis Linnaeus, 1758. This study was conducted in the Limfjord estuary, at Agger Tange, where C. gigas was introduced in 1972. The study site is a large cluster of raised intertidal bivalve beds inhabited by C. gigas and M. edulis in a sheltered part of the estuary. The two bivalves have some of the same living requirements, and as C. gigas have been present in the ecosystem for more than 40 years, we hypothesize that the presence of C. gigas has altered the spatial and temporal distribution of M. edulis by inducing a niche separation. The spatiotemporal development of the bivalve bed was determined using orthophotos. C. gigas and M. edulis were collected from the bivalve bed, shell lengths were converted into biomass, which were interpolated to create biomass contours and combined with modelled topography of the bivalve bed to study niche separation. The bivalve bed slowly extended northwards over a period of 11 years, where it also became more fragmented. The northern part of the bed was composed of mussel mats on top of soft sediment. This area was dominated by M. edulis, while areas in the south were dominated by C. gigas. In the southern part, the bivalve bed was composed of thick and compact sediment suggesting it represent the oldest part of the bivalve bed. There were no differences in the conditions of C. gigas and M. edulis from old or newly established areas, and there were no difference in the vertical distributions of the bivalve species. Thus, spatial and temporal separation of the two species is not pronounced at present, and thus unable to explain why they seemingly coexist.
 
The Indo-Pacific lionfishes (Pterois volitans [Linnaeus, 1758] and P. miles [Bennett, 1828]: Family Scorpaenidae) are the first non-native marine fishes to establish in the Western North Atlantic/Caribbean region. The chronology of the invasion was reported last year (Schofield 2009) using records from the US Geological Survey's Nonindigenous Aquatic Species database. This article provides an update of lionfish geographic spread (as of October 2010) and predictions of future range.
 
Charybdis feriata (Linnaeus, 1758). Collected near Barcelona, western Mediterranean Sea. Adult female (Carapace width: 125.0 mm; Carapace length: 81.3 mm) (ICMD 16/2005).
Location of the present record of Charybdis feriata (Linnaeus, 1758) off Barcelona in the western Mediterranean (black arrow). 200 and 1000 m isobaths are shown.
The Indo-Pacific portunid crab Charybdis feriata (Linnaeus, 1758) was recorded for the first time from the Mediterranean Sea, based on a single adult female caught in a gillnet off Barcelona at a depth of 60-70 m on the 13th December 2004. Its most probable introduction vector was a merchant ship.
 
The slipper limpet Crepidula fornicata Linnaeus, 1758 is a major exotic invader of East North Atlantic coasts. Individuals live on top of each other and form stacks with the youngest on the top. Earlier studies reported that one individual typically settles per year. If true, it is a simplified means to provide a “shell length-age” relationship for population dynamics studies, especially Production/Biomass ratio (P/B) assessment. However, estimated P/B ranges between 0.15 and 0.45 yr⁻¹ seem low compared to those of closely-related marine invertebrates and considering the invasiveness of C. fornicata in coastal habitats. In this study, we placed artificial substrates (“tiles”) for one year in the middle of a C. fornicata colony and measured settlement. We sometimes observed more than one individual settling per stack in a year: 4% of stacks were composed by 3 individuals, 27% by 2 individuals and 69% were single specimen. On this basis, we formulated a model to better link the position of each C. fornicata within a stack to its age. In addition, the C. fornicata population was annually sampled for 5 years. Then, population dynamics parameters, density at recruitment, mortality rate, growth performance, production and P/B were estimated. We compared two cases: (i) individual age was defined by its position in stacks; (ii) individual age was corrected by the model. Recalculation moderately increased growth performance expectation (+2 to 8% per year) but greatly enhanced production and P/B (ca. 1.2 to 2.6-fold per year). Recalculated P/B values ranged from 0.55 to 0.72 yr⁻¹. While still low, they were more consistent with published values for similar large marine invertebrates, in particular for invasive species.
 
Specimens of lionfish (Pterois volitans) observed (A, B, C and D) and collected (E) on the Venezuelan coast. A: specimen (~12 cm total length) photographed by Gustavo Quiroga on December 19, 2009 at 16 m depth, in Cayo del Norte, Parque Nacional Morrocoy. B: specimen (~14 cm total length) photographed by Rene Sleiman on January 3, 2010 at 27 m depth, in Chichiriviche de La Costa. C: specimen (~12 cm total length) photographed by María Padrón on January 9, 2010 at 17 m depth, in Cayo del Norte, Parque Nacional Morrocoy. D: specimen (~22 cm total length), photographed by Gabriela Carías on April 3, 2010 at 27 m depth, in Gran Roque, Parque Nacional Archipiélago de Los Roques. E: specimen (141 mm total length) collected by D. Granados and O. Correa on March 26, 2010 at 8 m depth in Playa Cal, east of Chichiriviche de La Costa (MHNLS 25906, Annex 1). Photo by O. Lasso-Alcalá. 
Distribution of Pterois volitans on the Venezuelan coast, southeastern Caribbean Sea. Each point corresponds to a locality. Records of observed specimens in numbers (see Annex 1). Records of collected specimens in letters (see Annex 2). 
We report the presence of the invasive Indo-Pacific red lionfish (Pterois volitans) in 23 localities of the Venezuelan coast, southeastern Caribbean Sea. This finding is based on ten specimens collected at Parque Nacional Archipielago de Los Roques (PNAR, Dependencias Federales), Playa Cal, Caraballeda and Puerto Carayaca (Estado Vargas) and 30 specimens observed in 18 localities of PNAR, Parque Nacional Morrocoy (Estado Falcon), Bahia de Cata, Ensenada de Cepe (Estado Aragua), Puerto Cruz, Chichiriviche de La Costa, Mamo, Catia La Mar, La Guaira, Macuto, Caraballeda (Estado Vargas) and Farallon Centinela (Dependencias Federales). The specimens were collected and observed from November 2009 to June 2010. This is the first published report documenting their occurrence in Venezuela.
 
Environmental predictor variables, including units of measure and sources, considered for modeling distribution of red lionfish.
Categorical model results showing the predicted distribution of red lionfish (Pterois volitans) in our study area. Models comparing GLM and Maxent models were constructed using native occurrence (A, B), non-native occurrence (C, D), and combined native/non-native occurrence (E, F) datasets. Predictions made outside the environmental range of each occurrence dataset were masked and are not included.  
Continuous model results showing the predicted distribution of red lionfish (Pterois volitans) in our study area. Models comparing GLM and Maxent models were constructed using native occurrence (A, B), non-native occurrence (C, D), and combined native/non-native occurrence (E, F) datasets. Predictions made outside the environmental range of each occurrence dataset were masked and are not included.  
Predictor variable marginal response curves for the top three contributing variables for each red lionfish (Pterois volitans) model (Native GLM, Native Maxent, Non-native GLM, Non-native Maxent, Native/non-native GLM, and Native/non-native Maxent). The environmental variables included: (A) bathymetry, (B) salinity, (C) pH, (D) minimum sea surface temperature, (E) maximum seas surface temperature, (F) mean chlorophyll A concentration, and (G) nitrate.  
We used two common correlative species-distribution models to predict suitable habitat of invasive red lionfish Pterois volitans (Linnaeus, 1758) in the western Atlantic and eastern Pacific Oceans. The Generalized Linear Model (GLM) and the Maximum Entropy (Maxent) model were applied using the Software for Assisted Habitat Modeling. We compared models developed using native occurrences, using non-native occurrences, and using both native and non-native occurrences. Models were trained using occurrence data collected before 2010 and evaluated with occurrence data collected from the invaded range during or after 2010. We considered a total of 22 marine environmental variables. Models built with non-native only or both native and non-native occurrence data outperformed those that used only native occurrences. Evaluation metrics based on the independent test data were highest for models that used both native and non-native occurrences. Bathymetry was the strongest environmental predictor for all models and showed increasing suitability as ocean floor depth decreased, with salinity ranking the second strongest predictor for models that used native and both native and non-native occurrences, indicating low habitat suitability for salinities < 30. Our model results also suggest that red lionfish could continue to invade southern latitudes in the western Atlantic Ocean and may establish localized populations in the eastern Pacific Ocean. We reiterate the importance in the choice of the training data source (native, non-native, or native/non-native) used to develop correlative species distribution models for invasive spècies.
 
Dietary shifts of invasive rudds Scardinius erythrophthalmus (Linnaeus, 1758) and food web structure of the upper Niagara River were examined. Stable isotope analysis (SIA) of liver tissue was used to test the hypothesis that rudds shifted their diets from piscivory during early spring months when macrophyte availability was low towards herbivory when macrophytes were abundant and warmer water temperatures facilitated digestion. Muscle tissue was used to evaluate the trophic position of rudds and other invasive species relative to native species. SIA revealed enriched δ15 N and depleted δ13 C in liver tissue of rudds during early spring months, suggesting a mostly piscivorous diet of pelagic origin when macrophyte availability was low, and depressed δ15 N and elevated δ13 C values during warmer summer months when littoral macrophytes were abundant. Analysis of muscle tissue from late summer indicated that rudds and other invasive fishes, including common carp Cyprinus carpio (Linnaeus, 1758) and goldfish Carassius auratus (Linnaeus, 1758), had similar trophic positions that may be attributed to their omnivorous feeding strategies. The ability of rudds to shift their diets from feeding on fishes of pelagic origin towards consuming littoral macrophytes is an adaptation that is likely to both facilitate invasion and create novel pathways of nutrient transfer among habitat types. Our results provide an increased understanding of the feeding ecology of the rudd and the role of this invasive species in the food web of the upper Niagara River.
 
Prince Edward Island (PEI), Canada, has seen the introduction and the establishment of many exotic tunicate species since the late 1990's. Exploratory research in the Orwell Bay identified turbidity as a potential factor in this failure of tunicates, and in particular Ciona intestinalis, to establish despite multiple unintentional introductions. Laboratory experiments showed significant negative effect of increased suspended inorganic matter on the fertilization success, larval settlement, and the survival of juvenile tunicates. Although the levels of turbidity tested (up to 22 and 32 NTU) reduced all of these processes it did not completely eliminate them. High levels of turbidity have the potential to prevent establishment of non-native tunicates in some locations where establishment would otherwise be expected.
 
Intra-annual and inter-annual reproductive periodicity for in situ populations of Ciona intestinalis were documented from October 2013 to August 2015 in the small vessel marina at the Bedford Institute of Oceanography in Dartmouth, NS. Three metrics of reproduction were monitored: (i) larval settlement, (ii) gonad development and (iii) gamete viability. In situ settlement was observed between June and November 2014. Gonad development during spring consisted of a sharp increase in the proportion of males followed by development into hermaphrodites, which resulted in a near entirely-hermaphroditic population throughout the summer and fall. The proportion of males and hermaphrodites began to decline by late fall; hermaphrodites were absent by early winter (i.e., late December or January), whereas males persisted at low abundance throughout the winter. In-vitro fertilization assays demonstrated that gametes became non-viable by early December. The seasonal changes in development stages were compared with respect to ambient seawater temperature and growing degree days. The spring maturation in 2014 occurred 3 weeks earlier than observed in 2015 (i.e., May 2014 and June 2015), likely due to a 2.0 °C higher mean seawater temperature than the same period in 2015. The effect of temperature on development rate was confirmed in a mesocosm experiment where the 3 °C elevated temperature treatment resulted in earlier sexual maturation by ten days for males and eight days for hermaphrodites compared to those in the unheated treatment. These results demonstrate the potential for an extended reproductive window, and perhaps extended geographic range, in response to predicted increases in ambient sea surface temperatures in Atlantic Canada in the next few decades.
 
Number and size of zebra mussels attached to P. clarkii, in Lake Trasimeno, during the summer periods 2011 and 2012.
Distribution (%) of attached zebra mussels on crayfish.
Observations of Procambarus clarkii fouling, by alien zebra mussels (Dreissena polymorpha) in Lake Trasimeno (and in the laboratory) are recorded. Results agree with previous reports that zebra mussels can be found, if only occasionally, on most parts of the swamp crayfish body, with a general preference for the ventral surface, and in this case, the pereopods. The frequency of colonization on P. clarkii in the wild varied from 0 to 4%; much lower than other crayfish species (e.g. 65% in Orconectes limosus or 12-24% in O. rusticus). Adults of both sexes were colonized equally. Multiple zebra mussels observed on individual crayfish were unexpectedly high; this may relate to poor crayfish condition and may also explain the only colonization of a live crayfish individual recorded in the laboratory.
 
The Indo-Pacific swimming crab Scylla serrata (Forskål, 1775) is reported here for the second time from the Southwestern Atlantic (Brazil). The species had been previously recorded from Brazil in the early 1980's. On both occasions individuals were captured near port areas.
 
The Eastern Mediterranean basin is facing a high invasion rate of mainly Indo-Pacific species entering through the Suez Canal. The needle-spined urchin, Diadema setosum, was first documented in the Mediterranean in 2006 off southern Turkey. The new record of D. setosum in September 2009 represents the first evidence of its presence in Lebanese coastal waters.
 
Lobotes surinamensis is considered as a rare occurrence in the Mediterranean Sea, being mainly encountered in the eastern and central areas of the basin. The species was previously recorded only once from the Maltese Islands, from offshore waters 45 miles south of the islands. Numerous recent records of the species in Maltese nearshore waters suggest that the same species is becoming more common in such waters, possibly hinting at the geographical expansion of populations of this thermophilic fish species in the Mediterranean.
 
The distinctive Mediterranean-Atlantic fanworm polychaete, Sabella spallanzanii (Gmelin, 1791), is recorded from New Zealand, in both North and South Island, consequent upon its discovery first in the port area of Lyttelton in Lyttelton Harbour and later 800 km further north in the port area of Auckland in Waitemata Harbour. Morphology distinguishing the species from other sabellids is highlighted. In the initial occurrence in March 2008 one large specimen was identified from samples taken by a surveillance team off subtidal wharf structures in Lyttelton port. In July and August 2008 further large specimens were found both nearby and dispersed across the inner port area, with reproductive maturity appearing imminent in some. The New Zealand Government funded repeated search and culling by divers, directed towards possible local elimination, with over 380 specimens removed from Lyttelton by December 2009. However, in August 2009 a single large specimen was found in an enclosed port area in Waitemata Harbour, then several more, and in October 2009 numerous specimens were found on a barge hull berthed there. Also it became apparent that a second generation of colonisers was present in both harbours. By early 2010 well-grown specimens had been found in disparate Waitemata Harbour locations over a large area. The decision to suspend culls was made in February 2010, and elimination efforts were abandoned in June 2010, two years after first detection. The arrival and apparent establishment of S. spallanzanii in New Zealand is ascribed to accidental international transfer probably in 2007, either via hull fouling or ballast water, but it is not known if the two ports were colonised via the same transiting vessel.
 
Records of Polydora cornuta in the Mediterranean and Black Seas (Tena et al. 1991;  Çinar et al. 2005a; Radashevsky 2005; ■ Boltachova and Lisitskaya 2007; ▲ Present study). See Annex 1 for details. 
The present study reports the first occurrence of an alien spionid polychaete Polydora cornuta Bosc, 1802, in Izmit Bay, Sea of Marmara, Turkey. A dense population of P. cornuta (up to 170 ind.m-2) found at 7 sampling stations in the bay on 18 August 2006. Our findings show that currently this alien polychaete is a key species of polluted soft bottom benthic assemblages in Izmit Bay.
 
The Pontian monkey goby, Neogobius fluviatilis, was recorded for the first time in the Netherlands in March 2009. Seven specimens were caught in the lower parts of the River Rhine, at close distance of the German border. Based on the species invasive history, N. fluviatilis could become invasive. Potential ecological impacts should therefore be studied.
 
South Island water bodies where Daphnia 'pulex' has been sampled to date. 
Lithophaga aristata is a boring bivalve native to the Caribbean Sea, first recorded in 2005 as an introduced species on the Southeastern Brazilian coast. The geographic distribution and density of L. aristata and of its native congeneric L. bisulcata were assessed in four areas of Brazil (24 sites), additionally considering their relationship with types of substrate, depth and wave exposure. This study records the first occurrence of L. aristata in the Sepetiba Bay and also reports the species at five new localities in the Arraial do Cabo Bay. Lithophaga aristata is established in the four surveyed regions. At intertidal habitats, the exotic species only colonizes the infralittoral fringe but its density was not related to wave action. At subtidal habitats, the species colonizes natural and artificial substrates, from shallow (0.5m) to deep (5.0-7.0m) zones but no relationship between density and these evaluated factors was detected. Broad geographical and ecological distributions and higher densities of this introduced species in relation to its native congeneric are suggested as contrary to Darwin's naturalization hypothesis and instead indicate a high invasiveness potential.
 
Records of Limnoperna securis and map showing the study area and the locations of the four stations where this species has been collected. 
Records of Limnoperna securis in the world.
Limnoperna securis (from Nervión estuary, Spain) (a) inner part of Nervión estuary; (b) site of intertidal sampling stations; (c) adult; (d, e, f) juveniles; (g) patches of L. securis in rocky; (h) colony attached to a stone; (i) specimens of L. securis collected at Station D (Photographed by Julián Martínez).
The occurrence of the non-indigenous species Limnoperna securis belonging to Mytilidae family is recorded for the first time in the Bay of Biscay. Numerous individuals were collected in intertidal and shallow waters in the inner part of Nervión estuary (Bizkaia, Basque Country, SE Bay of Biscay). In the present paper, notes about the history of this small brown mussel invasion, vectors of introduction and dispersal, as well as consequences of invasion are discussed.
 
Location of the study area: Gulf of Riga, and inner (1) and outer (2) station in Pärnu Bay (NE Gulf of Riga).  
Sampling details in the Gulf of Riga (GoR) and the outer station of Pärnu Bay (PB). Sampling depth in PB was 10m. 
Evadne anonyx (upper) and Evadne nordmanni (lower). Photo by M. Kalaus.  
Spatial distribution and abundance (individuals m -3 ) of the non-indigenous Evadne anonyx in the Gulf of Riga in summer 2001–2012.  
Comparison of the abundance estimates of the nonindigenous cladoceran Evadne anonyx based on Sub-sampling and total sample counts. Grey dots indicate samples, where subsampling failed to detect E. anonyx  
The recruitment and population structure of the non-indigenous brackish water mytilid Xenostrobus securis (Lamark, 1819), native to Australasia, were studied in the lower reaches of the Kino River, central Japan. Post-larvae > 2 mm in shell length were found exclusively among barnacle stands of Fistulobalanus kondakovi (Tarasov and Zevina, 1957) and algal fronds of Gloiopeltis tenax (Turner) Decaisone, 1842 from January to May and from July to October. Density of the post-larvae was much greater in the latter period than in the former. Small mussels with shell lengths of 2-4 mm settled to the conspecific mussel beds in April and September. Primary and secondary settlements onto different substrates were observed in the early stages of the life cycle. Two or three cohorts were identified in conspecific mussel beds, and they grew at a rate of ca. 1 mm per month. Density in the beds fluctuated monthly and was greater in the lower than in the middle intertidal zone, suggesting greater spatial heterogeneity in density due to predation in the former.
 
Ameiurus melas specimens collected in the Guadalquivir Estuary. Detail of an adult specimen (LT = 304 mm) (a); detail of specimens of different size (b); details of the mouth and barbles (c), first dorsal fin rays (d), pectoral fin rays (e) and caudal fin rays (f) (Photograph by J. Garcia-de-Lomas)
Total length ( L T , mm) of Ameiurus melas in the 
Total length (LT, mm) of Ameiurus melas in the 2008 survey. Sample size (n) of each month is indicated
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.
 
Hypselodoris infucata from Lara Beach Gulf of Antalya (Photographs by Levent Yasin Atik). 
Map showing the locality where Hypselodoris infucata species was found in Turkey and Cyprus Coasts (latest record in red, see Table 1 for details). 
The Indo West Pacific opisthobranch, Hypselodoris infucata, first recorded in the Gulf of Iskenderun, Turkey, in 1999, is now reported from the Gulf of Antalya (on 13 July 2010).
 
Chaetodon larvatus HUJ 20053, 89.9 mm (SL), 15 January 2011, Haifa Bay, Israel. Photograph by D. Golani. 
The Red Sea species, the Orangeface Butterflyfish, Chaetodon larvatus, is recorded for the first time from the Mediterranean. Its occurrence there is evidentially the result of entering the Mediterranean via the Suez Canal.
 
Sinanodonta woodiana from river channel Mali Strug, Nature Park Lonjsko polje.  
Empty shell of Sinanodonta woodiana on banks of channel Hulovo, Nature Park Kopački rit.  
The Chinese pond mussel Sinanodonta woodiana is an invasive bivalve species present in the flowing and standing waters of most of Europe. Field research conducted from 2007 to 2011 indicated that this species has colonised the entire eastern part of Croatia, and that its spread westward is continuing. During our study, S. woodiana was recorded at 54 localities.
 
Study area and record locations of Anodonta woodiana in Lake Maggiore (see Appendix 1 for geographic coordinates); red circles-sites with Anodonta woodiana, blue-absent.
Morphometric measurements of Anodonta woodiana collected in Lake Maggiore during March 2012.
Anodonta woodiana : W – width, L – total length, h – wing/top ventral edge height shell measurements (mm). Photographs by Lyudmila Kamburska. 
This note is the first communication of the occurrence of the alien Anodonta (Sinanodonta) woodiana (Lea, 1834) (Bivalvia: Unionidae) in Lake Maggiore (Northern Italy). We have found empty shells of the bivalve first in August 2010, and since then, this species is colonizing rapidly the second deepest subalpine lake in Italy. Preliminary findings on morphometric features of A. woodiana in the Lake are provided.
 
Bellamya chinensis, an Asian species, is reported for the first time from the Netherlands. These records are also the first reports from Europe. The species is commercially sold for garden ponds and aquaria, from which they may have escaped or been released. It is anticipated that this species will become invasive in the Netherlands and beyond.
 
Eriocheir sinensis H. Milne Edwards, 1853; NHM 1993:1, River Cray, Hall Place near Crayford, Kent, collected B. Martin, 20 August 1992, right chela showing spines on internal surface of propodus (circled). These spines are normally obscured by the mittens in male crabs. Taken by Harry Taylor, NHM Photo Unit. Scale bar in mm divisions of 1 cm  
Eriocheir sinensis H. Milne Edwards, 1853; NHM 1993:1, River Cray, Hall Place near Crayford, Kent, collected B. Martin, 20 August 1992, showing the prey grasping coadaptation between spines on internal surface of the right chela propodus and those on the merus (circled). These spines are normally obscured by the mittens in male crabs. Taken be Harry Taylor, NHM Photo Unit. Scale bars in mm divisions of 1 cm  
Average rate of energy consumption ± SE by sub-adult Eriocheir sinensis for three prey species  
Dispersal of Eriocheir sinensis from its native habitat is a worldwide concern. As one of the most invasive species known, this crab causes significant disruption to foreign ecosystems. In particular, populations in the United Kingdom (UK) are increasing in number and E. sinensis has been reported from many river catchments. The ecological implications of this invasion are not fully understood. One aspect of concern lies in the potential for mitten crabs to predate fish eggs which, if realistic, could contribute to the decline of riverine populations. In this study, 100 mitten crabs from the River Thames were used in experimental feeding trials to 1) investigate foraging ability on a variety of fish eggs and 2) establish whether crab size affected foraging potential. Eggs ranged from 1–6 millimetres (mm) in diameter from one of four species of marine and freshwater fish; zebrafish, lumpfish, Pacific salmon and trout. Predation by crabs varied with egg type; crabs were capable of foraging 1mm zebrafish eggs, but the majority consumed eggs 2–6mm in diameter. The most attractive eggs were apparently lumpfish, where the median proportion consumed was 100%. Crab size did not appear to govern foraging potential, though variation was observed in the size range of juvenile crabs consuming the different eggs with the largest, salmon, being consumed by crabs of the broadest size range. E. sinensis does have the potential to predate on a range of fish eggs, and the results are used to infer the risk presented to specific groups of UK fish stocks.
 
Specimen of Omobranchus punctatus collected on Algodoal-Maiandeua Island in 2010. 
Physical-chemical parameters of the water from the tidal pools in which the specimens of Omobranchus punctatus were collected on Algodoal-Maiandeua Island in 2008 and 2010.
Location of the study site, Algodoal-Maiandeua Island in northeastern Pará (Brazil), where the specimens of Omobranchus punctatus were collected in tidal pools in 2008 and 2010.
Locations at which the non- native blenny Omobranchus punctatus has been recorded on the Brazilian coast in published and unpublished reports, including the present study. 
The muzzled blenny Omobranchus punctatus (Valenciennes, 1836) is native to the Indo-Pacific region. The species has been recorded at a number of locations in the southwestern Atlantic, including the Brazilian states of Bahia, Santa Catarina, and Rio de Janeiro. This fish was probably introduced accidentally in ship fouling, and poses a potential threat to the local ecosystem.
 
First detected in the United States in Idaho's Snake River in 1987, the New Zealand mud snail (NZMS), Potamopyrgus antipodarum, was discovered in Olympia Washington's Capitol Lake in 2009. The snail is not native to North America and may be capable of adversely impacting native species diversity and food web dynamics in aquatic ecosystems. In this study, we evaluated the effect of lowering the lake level during freezing weather on the survival of NZMSs. Both generalized linear models with link function logit and nonlinear mixed effects models were used to investigate the rates of detection and survival with four temporal and environmental predictor variables. The rate of detection of NZMSs was affected by substrate depth and proximity to shore. The location of sample stations (upshore versus offshore), substrate depth, and elapsed time between collection from the field and laboratory processing did not affect survival rates. The survival rate of NZMSs decreased rapidly with time and the predicted survival rate at the conclusion of the freezing episode was 1.8%. The results indicate that lowering the water level during freezing weather can be a highly effective means for controlling the distribution and abundance of NZMSs and reducing the risk of their spread to other water bodies.
 
The Western Pacific Ocean barred knifejaw Oplegnathus fasciatus was found from 2013 to 2015 along the Pacific Coast of North America from Washington to California. The knifejaw was found in derelict vessels that had arrived on the Pacific Coast and that had been lost during the March 2011 Great Japan Earthquake and Tsunami. Knifejaw were also found free living in the wild in regions known to have received Japanese tsunami marine debris. No previous records of O. fasciatus are known east of the Hawaiian Archipelago.
 
Photograph of JTMD-BF-356 at the time of discovery off the coast of Seal Rock, Oregon, USA. Photograph by John Chapman. 
Japanese yellowtail jacks, Seriola aureovittata, within the hold of a Japanese derelict fishing vessel, 9 April 2013, and after capture. Photograph of fish in the well by James Burke. Photograph of fish after capture by Caren Braby. 
A. Neighbor-Joining phylogram based on Kimura-2 parameter distances of 564 base pairs of the nuclear EEHADH gene for yellowtail jacks, Seriola spp. B. Neighbor-Joining phylogram based on Kimura-2 parameter distances of 655 base pairs of the nuclear EEHADH gene for yellowtail jacks, Seriola spp. In both phylograms the yellowtail jacks associated with vessel JTMD-BF-356 cluster with the Japanese yellowtail jack, Seriola aureovittata, indicating that they are the same. Scale bar is substitutions/site. CA = California, U.S.A, CH = Chile, JP = Japan, MG = Mexico (Gulf of California), MP = Mexico (Pacific), NZ = New Zealand, OR = Oregon, SA = South Africa.
The devastating tsunami of March 2011 on the Pacific coast of Japan produced abundant marine debris which drifted across the Pacific Ocean to North America. Here we document rafting of the Japanese yellowtail jack Seriola aureovittata Temminck & Schlegel, 1845 (Carangidae) across the North Pacific inside a tsunami-generated derelict vessel. Long-distance transport of rafted fish may be an infrequent but potentially consequential mechanism for the introduction of invasive fish, especially given the increasing volumes of debris in the world’s oceans.
 
Mean (SD; n=3) relative abundance of sessile invertebrates on two rocky intertidal shores in southeastern Brazil in spring and summer of 1990-1991 and 2002-2003, before and after Isognomon bicolor invasion, respectively.
Scientists recognize the importance of ecological data prior to invasion by non-native species in order to evaluate changes in the recipient community. Here we assess the potential impact of the invasion of the bivalve Isognomon bicolor (C.B. Adams, 1845) on Brazilian rocky shores through the use of surveys both before and after the arrival of this non-native species. The invader was mostly distributed across the mid and low shore levels of the intertidal zone with relative abundance ranging from 9.0 to 36.7 percent cover. The mid shore, previously dominated by the native barnacle Tetraclita stalactifera (Lamarck, 1818), was co-dominated by this barnacle species and I. bicolor after invasion. The relative abundance of these species, and presumably the interaction strength between them, differed between sites. At the site where I. bicolor reached the highest abundance (around 30% on average), the abundance of T. stalactifera decreased on average 70% compared to baseline values obtained before the I. bicolor invasion. Finally, conspicuous and extensive I. bicolor beds such as those observed in this study have not been reported in its original distribution range. Beds of I. bicolor may create a much more intricate biogenic matrix than the extents of bare rock and barnacle clumps it replaced. This bivalve may act as an ecosystem engineer and, thus a functionally different component of the intertidal community in its invaded range compared to its native distribution.
 
Forty-two specimens of Macrobrachium nipponense (de Haan, 1849) were collected from Abu-Zirig Marsh in the south of Iraq, in July 2005. DNA sequences confirmed the morphological identification by 99 % similarity to published 16S sequences. The
 
Map of the Tagus Estuary (central western Portugal) showing the area where the fishing surveys were performed for collecting the samples of the Manila clam (Ruditapes philippinarum). 
Photographs of acetate peel sections of Ruditapes philippinarum. A) acetate peel of sectioned shell illustrating the two layers; B) outer prismatic layer exhibiting two distinct growth patterns; C) annual growth ring associated with a cleft on the shell surface; D) false growth ring associated with a cleft on the shell surface; E) acetate peel illustrating the distinction of annual growth rings (progressive narrowing of growth bands) from false rings (sudden interruption of the natural growth pattern). OL, outer composite prismatic layer; IL, inner homogeneous layer; SG, slow growth, FG, fast growth; AR, annual ring; FR, false ring. Photo by P. Moura. 
Variation of the growth performance index (phi-prime, φ') according to the geographical location (latitudinal and longitudinal coordinates) of the populations of Ruditapes philippinarum distributed worldwide. Circles delimit the groups of populations from different continents (Tagus Estuary-star; Europe-squares; Asia-circles; North America-triangles) and the interrupted line (φ' = 3.050) separates the populations introduced in Europe from the remaining populations (introduced in North America and native from Asia). Further details on those populations of the Manila clam (numbers, locations and references) are compiled in Table 2. 
Auximetric grid for comparison of the overall growth performance (OGP, P) between populations of Ruditapes philippinarum (Tagus Estuary-star; other populations-squares) and Ruditapes decussatus (triangles) distributed worldwide. Diagonal lines indicate equal OGP values. Further details on those populations of the Manila clam (numbers, locations and references) are compiled in Table 2. 
The Manila clam Ruditapes philippinarum (Adams & Reeve, 1850) was introduced in several regions worldwide where it is permanently established. In Portuguese waters, the colonisation of the Tagus Estuary by this invasive species coincided with a significant decrease in abundance of the native Ruditapes decussatus (Linnaeus, 1758). This study aimed to estimate the age and growth of the Manila clam, to compare the growth performance between R. philippinarum and R. decussatus in several locations worldwide, and to ascertain whether the Manila clam’s growth patterns contributed to the extensive distribution of this invasive bivalve in the Tagus Estuary. The growth of R. philippinarum in the Tagus Estuary was described through the von Bertalanffy equation SLt=65.2[1−e-0.34(t+0.93)], corresponding to a phi-prime index (φ’) of 3.160 and an overall growth performance of 4.974. This growth performance is the second highest recorded for R. philippinarum worldwide and was much higher than that of R. decussatus from Portugal. This study confirmed that the Tagus Estuary presents near-ideal environmental conditions for growth of the Manila clam. R. philippinarum displayed clearly invasive behaviour, spreading widely and growing faster than the native R. decussatus, which certainly contributed to the decline of its populations in the Tagus Estuary.
 
Geographic distribution of of haplotypes of Procambarus clarkii, within the native range (in grey) and those introduced, included in this study: ILL, Illinois, U.S.A.; LA, Louisiana, U.S.A.; CH, Las Varas, Chihuahua, Mexico; CON, Río Jimenez, Coahuila, Mexico; COC, Río Sabinas, Coahuila, Mexico, NL, Sabinas Hidalgo, Nuevo Leon, Mexico; DU, El Arenal, Durango, Mexico; CHIS, Teopisca, Chiapas, Mexico; CR, Cachí Dam, Costa Rica.  
Localities of the analyzed native (bold) and introduced populations of Procambarus clarkii in Mexico, United States and Costa Rica.
Distance tree (NJ) based on 37 sequences with population, haplotype and outgroup, based on a GTR nucleotidic model. Bootstrap values above the branches correspond to ML analysis and to MP below the branches. In green: localities from the native range, in red: the introduced ones.  
Haplotype network constructed using the haplotypes of the COI gene of Procambarus clarkii. Small circles represent intermediate haplotypes not obtained in the analysis. Letters a-l refer to the different haplotypes, other abbreviations correspond to the localities, in green haplotypes from the native range, in red the introduced ones.  
The genetic variation among nine populations of the red swamp crayfish Procambarus clarkii was examined using partial sequences of the mitochondrial COI gene. Three populations (Illinois and Louisiana, United States and northern Coahuila, Mexico) represented the native range and six populations came from areas where the species has been introduced (central Coahuila, southern Nuevo León, Durango, Chihuahua and Chiapas, Mexico, and Cartago, Costa Rica). A 689 bp fragment was amplified from 37 samples. Uncorrected genetic distances among sequences were p = 0 to 0.02031 and 12 haplotypes were found. A phylogenetic reconstruction shows that the three populations from the native range remain very similar to each other and some introduced populations can be directly associated to one of them. The populations from Nuevo León, central Coahuila and Costa Rica were the most divergent ones. Overall the genetic variation found in P. clarkii in both native and introduced populations is low.
 
The list of P. clarkii specimens preserved at the National Zoological Collections, Tel Aviv University
Procambarus clarkii: A-a large male, observed on 6 May 2008, night survey; B-in a water-filled burrow, 28 April 2008; C-two males observed at the mouth of a burrow, 28 April 2008; D-a gravid female, 28 April 2008. Photographs by Gil Wizen
The recent findings of the red swamp crayfish, Procambarus clarkii, in groundwater-filled pits in an abandoned quarry (Hadera, central coastal plain) constitute the first record in the wild of this notoriously invasive species in Israel. Crayfish had been offered for sale in local pet shops: twenty years ago several illegally imported specimens had been confiscated by the Israel Nature and Parks Authority and two of the specimens were deposited at the National Collections, Tel Aviv University. The recent finding of a small reproducing population established in a semi natural habitat in Israel raises great concern regarding the potential widening of its range and of the limited options for its eradication.
 
Top-cited authors
Michal Grabowski
  • University of Lodz
Argyro Zenetos
  • Hellenic Centre for Marine Research
Ana Cristina Cardoso
  • European Commission
Stelios Katsanevakis
  • University of the Aegean
Melih Ertan Çinar
  • Ege University