During the late 20th century, several species of alien tunicates invaded New England marine coastal waters. In Autumn 2008, we surveyed for tunicates in Lake Tashmoo, a protected marine pond with shellfish aquaculture operations and restored bay scallop Argopecten irradians irradians habitat on Martha’s Vineyard, Massachusetts. We found the invasive tunicates Ascidiella aspersa, Botrylloides violaceus, Botryllus schlosseri, Didemnum vexillum, Diplosoma listerianum, Styela clava and native tunicate Molgula manhattensis attached to artificial substrates throughout Lake Tashmoo and B. violaceus, B. schlosseri, D. vexillum, D. listerianum and M. manhattensis attached to eelgrass Zostera marina in the middle of Lake Tashmoo. Tunicates were growing on the stalk and blade of in situ eelgrass, floating pieces of eelgrass (a transport and dispersal mechanism), and pieces of eelgrass in fouling communities on boat hulls and aquaculture floats. Botrylloides violaceus, B. schlosseri, D. listerianum and M. manhattensis have been previously recorded as utilizing eelgrass as substrate, but this is the first recorded occurrence of D. vexillum to utilize eelgrass as substrate. Perhaps because of lack of substrate space in Lake Tashmoo, D. vexillum spread to eelgrass. Eelgrass serves as a juvenile shellfish and fish habitat and threats to it are of concern by coastal managers and the fishing industry.

Invasive, non-indigenous ascidians have been a significant biofouling problem for the aquaculture industry in Nova Scotia and Prince Edward Island since the mid-1990’s. The problematic species in Atlantic Canada include Styela clava, Ciona intestinalis, Botryllus schlosseri and Botrylloides violaceus. Newfoundland harbour surveys that we have performed over the past three years revealed the presence of B. schlosseri and B. violaceus. As of yet, neither of these species has reached invasive abundance in Newfoundland.
Portions of the COI genes of two non-indigenous ascidians (Botryllus schlosseri and Botrylloides violaceus) and two indigenous ascidians (Boltenia echinata and Halocynthia pyriformis) were cloned and sequenced. We then determined intraspecific and interspecific COI sequence variation. The BLASTN results showed that Botryllus schlosseri and Halocynthia pyriformis match the other listings for these species in GenBank. However, the BLAST results from Botrylloides violaceus were more similar to B. schlosseri than B. violaceus. While there were no other entries for Boltenia echinata, it was similar to other species in the Pyuridae family. Intraspecific similarity in the COI sequence for Newfoundland populations was >99.7% for B. violaceus, H. pyriformis and B. echinata, and 86.5-96.6% for B. schlosseri. Interspecific similarities among all four species were <80.3%. This indicates that the COI gene should be an effective species-specific molecular marker for the identification of eggs and larvae of these Newfoundland ascidians.

Visual searches are a common method of detecting invasive species in coastal waters, but the statistical properties of search methods have rarely been evaluated. Understanding the error rate (especially false negatives) and effective detection distance of searches can improve survey design, and quantify the uncertainty in risk assessments used to inform invasive species management efforts. An experiment using artificial tunicates (“decoys”) was conducted in Hillsborough Bay, Prince Edward Island, to determine the effectiveness of SCUBA divers conducting underwater visual searches for the vase tunicate, Ciona intestinalis (Linnaeus, 1767). Single decoys and clusters of three decoys, constructed from water-filled, ivory-coloured balloons 5-6 cm in length, were placed at a blue mussel, Mytilus edulis (Linnaeus, 1758), aquaculture site on buoys, lines and mussel socks. The probability of detecting tunicate decoys on a mussel sock in the experiment is 89.8% (±SD 7.1), known in this paper as a true positive. The probability of not detecting tunicate decoys actually placed on a mussel sock in the experiment is 10.2% (±SD 7.1), known in this paper as a false negative. Divers detected 79.2% (±SD 7.1) of single decoys and 94.0% (±11.4) of clusters. Divers were able to detect single decoys from a measured horizontal distance of 2.7 m (±0.8), and clusters from 2.8 m (±0.9). The typical detection distance for real C. intestinalis estimated by divers was, on average, 2.1 m (range 1 - 3 m), and tunicates of lengths ≥ 2.9 cm (range 1-4 cm) could be detected.

The bivalve Limnoperna fortunei (Dunker, 1857), also called golden mussel, is native to Asia but becoming dispersed around the world. The golden mussel resembles the invasive dreissenid bivalves in many respects, and although much less studied it evidently has broader environmental tolerances. The golden mussel was introduced into the La Plata River estuary (South America) and quickly expanded upstream to the north, into the tropical Paraguay River reaching a large floodplain area in Brazil known as the Pantanal wetland. The golden mussel tolerates environmental conditions in the Pantanal that would be inhospitable for most bivalves, but mussel mortality has been observed during the most extreme oxygen depletion events. Based on knowledge about the limiting factors for the golden mussel in the Pantanal wetland, its potential distribution was predicted for the remainder of the Paraguay River basin where the species is not present, as well as in other river systems throughout Brazil. Forecasts of potential distribution in Brazilian river systems were based on physicochemical limitations for shell calcification, and specifically on lower thresholds of dissolved calcium concentrations and the calcium carbonate (calcite) index of saturation, which may be a better indicator of calcification potential in low-calcium waters than calcium concentration alone. In addition to examining spatial patterns in calcium and calcification potential, these and other limnological and climate variables were used in ecological niche modeling using GARP and Maxent algorithms. Forecasts of potential distributions in three major North American river systems (Mississippi, Colorado, and Rio Grande) were based mainly on water temperature because calcium availability and calcification evidently would not be limiting to golden mussel establishment in those waters. Due to the greater tolerance of the golden mussel to conditions known to limit other bivalves, as well as its greater ability for shell calcification in low-calcium water, the golden mussel could potentially become broadly distributed throughout Brazil. According to its thermal tolerance L. fortunei could become established in the Mississippi, Colorado and Rio Grande drainage systems, although the northern Mississippi River system including the Missouri River may be too cool in the winter to support the golden mussel.

Signal crayfish Pasifastacus leniusculus were first discovered in Norway in the Dammane area of Telemark County in October 2006. This introduced population was found to be infected with the oomycete Aphanomyces astaci, the causative agent of crayfish plague. The Dammane watershed consists of 5 small ponds, the largest with a surface area of approximately 2000 m². The Norwegian National Veterinary Institute conducted a feasibility study for the eradication of the Dammane signal crayfish population at the request of the Norwegian Food Safety Authority and Directorate for Nature Management. This study recommended the use of the pharmaceutical BETAMAX VET.^®, followed by pond drainage as a feasible course of action. BETAMAX VET.^® is a cypermethrin-based pharmaceutical developed for treatment of salmon louse (Lepeophtherius salmonis) infestations of farmed Atlantic salmon (Salmo salar). Cypermethrin is a synthetic pyrethroid and a common agent in many insecticides licensed throughout Europe. Following a comprehensive mapping of the Dammane watershed, the ponds were treated with BETAMAX VET.^® on the 14 and 28 May, 2008. Subsequently, the ponds were drained by pumping out the water in two separate stages on 2-4 June, 2008 and 22-24 December 2008. During the first treatment with BETAMAX VET.^®, signal crayfish were captured in the two upper ponds. During and following the second treatment and draining of the ponds, no signal crayfish were found. The ponds were gradually re-filled with water during the spring of 2009. It is too early to conclude whether the treatment has led to the complete eradication of the signal crayfish, but the results so far are promising. We believe that BETAMAX VET.^® can be a useful tool in managing alien crayfish populations.

The eastern mudminnow Umbra pygmaea (DeKay, 1842) originates from the eastern part of the United States of America and was transferred to Europe already at the beginning of the 20th century. This paper summarizes the current distribution in Europe and adds an extended dataset of eastern mudminnow records in Flanders (Belgium). The core of the European distribution seems to be the southeast of The Netherlands and the northeast of Flanders. Eastern mudminnow is established in lotic waters in Flanders and was found on 76 locations over the last 15 years. Neutral pH and high oxygen concentrations positively correlate with the presence of eastern mudminnow. The abundance of U. pygmaea decreases significantly with an increase of the number of fish species. The length-frequency distribution shows a peak at 7.0 cm and total length of U. pygmaea specimens varies between 3.4 and 13.7 cm. The overall length-weight relationship for all U. pygmaea specimens in Flanders shows a positive allometric growth. Fulton’s condition factor for all eastern mudminnow specimens caught in Flemish rivers is 1.22. Assessment of U. pygmaea on its potential invasiveness in Flanders results in a low to medium risk.

The hoplo catfish [Hoplosternum littorale (Hancock, 1828)] is a callichthyid catfish native to South America. It was first recorded in Florida in 1995. It has now dispersed throughout much of Florida. It is thought that this fish has had little or no impacts to native fish. However, it is unknown if the introduction of this fish can cause other ecological impacts, such as alteration of aquatic invertebrates assemblages. We conducted a cage experiment to evaluate the effects of the hoplo catfish on macroinvertebrates. Results showed that macroinvertebrate abundance and taxa on artificial substrates (MAS) were reduced by 31 and 50% in the fish treatments, respectively. The entire macroinvertebrate assemblage structure was significantly different between fish and no-fish treatments. This difference was driven primarily by reductions in amphipods, and chironomids. Macroinvertebrates were also identified from fish stomachs and these were compared to assemblages on the MAS. We found a smaller subset of taxa in the stomachs, as compared to the MAS. These results suggest that this fish could alter the macroinvertebrate assemblage structure. This could have implications for environmental monitoring programs that use macroinvertebrates to assess water quality.

As of the end of 2008, 25 species of non-native fishes have been documented in the Republic of Belarus. Of these, 17 (68%) species were deliberately introduced for aquaculture, six (24%) species invaded from the adjacent territories by natural dispersal, and two (8%) species were likely introduced accidentally. During the 20th century, the number of non-native fishes in Belarus increased exponentially, resulting in significant shifts in taxonomic composition of the country’s ichthyofauna. For the first time, we assessed the invasive potential of the introduced fishes by applying a uniform protocol, the Fish Invasiveness Screening Kit (FISK). Based on the total FISK scores, all the non-native fishes in Belarus were classified into two groups: high and medium risk of becoming invasive. In terms of the economic sectors at risk (‘aquacultural/fisheries’, ‘environmental’, and ‘nuisance’), all species were classified into three distinct groups. The highest risk to all of these sectors was posed by the brown bullhead Ameiurus nebulosus Le Sueur, 1819, gibel carp Carassius gibelio (Bloch, 1782), round goby Neogobius melanostomus (Pallas, 1814), Amur sleeper Perccottus glenii Dybowski, 1877, and topmouth gudgeon Pseudorasbora parva (Temminck & Schlegel, 1846). The two risk categories identified in the present study can be used in prioritizing the resources for the management of non-native fish species of Belarus and in countries with similar environmental conditions.

Oceangoing ships contribute to the introduction of invasive, benign and pathogenic bacteria via ballast water discharge. Here we report the bacterial abundance and cell size in ballast and receiving port waters in Vancouver, British Columbia (Canada) ports during 2007 and 2008. Bacterial abundance in port water (7.5×10⁸ to 3.4×10⁹ cells L^-1) was significantly (P < 0.001) higher than those in ballast water (2.5×10⁸ to 2.1×10⁹ cells L^-1) and was higher in unexchanged than ballast water that was exchanged at-sea. There was no significant difference in bacterial abundances between 2007 and 2008 for each sample type. Bacterial cell volume showed a different pattern, with no significant difference among sample types and a two-fold larger average cell volume during 2007 than 2008. Bacterial abundance and cell volume in ballast water were not correlated with ballast water age, end-of-voyage temperature, salinity or pH. The absence of predictive relationships between measured physiochemical and bacterial variables in ballast water highlights the difficulty of predicting bacterial abundance or cell volume from the physiochemical factors alone. Future studies should focus on the bacterial community structure in ballast and port waters, the fate of bacteria in the new environment, and regional susceptibility to invasion by the introduced bacteria.

Bacterial abundance, population dynamics and related environmental parameters were determined in ballast water during a trans-Pacific voyage from Japan to the west coast of Canada. Water samples were collected from four ballast tanks, two of which underwent mid-ocean exchange (MOE) and two that remained unexchanged (control). Bacterial abundances in the unexchanged tanks increased from ~6.4×10⁸ cells/L on Day 0 to 1.8×10⁹ cells/L on Day 7, whereas in MOE tanks, abundances increased from approximately 8.6×10⁸ cells/L (Day 0) to 2.2×10⁹ cells/L (Day 10) before MOE (Day 14). After Day 10, bacterial abundances in all ballast tanks declined. Despite the greater decline in MOE tanks, the final abundances in the MOE and unexchanged tanks were not significantly different, which suggests MOE alone is not effective in reducing the risk of transferring the number of bacteria. Bacterial abundance was assessed with respect to changes in environmental parameters within the tanks and we found a significant increase with increased temperatures and a decrease with increased dissolved oxygen concentrations (p<0.001). If the relationship between bacterial abundance and both temperature and dissolved oxygen concentrations is shown to be a general characteristic for ballast water, new control protocols could be developed to minimize the number of bacteria being deballasted into coastal harbors.

University researchers and government agency scientists can join new allies in efforts to increase public understanding of aquatic invasive species. More than 200 “free choice learning” centers accredited by the Association of Zoos and Aquariums, along with Sea Grant programs across the United States, have received Aquatic Invaders program toolkits as part of an outreach project funded by NOAA’s National Sea Grant College Program. Surveys results show that the AZA educators have already reached audiences totaling at least 10,000 with messages to limit the introduction and spread of AIS. The educators also report significant increases in their own understanding of invasive species. The kit reflects a successful project that brought together scientists and educators for a program designed on a national scale, yet can be adapted for local use/emphasis.

A special session at the 2009 ICAIS meeting offered participants a chance to experience an outstanding “free choice learning” center: the Montreal Biodome. The setting sparked an engaging discussion of AIS outreach opportunities with partners including members of the Association of Zoos and Aquariums and other educational institutions.