Increasing public awareness is a prerequisite for successful management of invasive alien species (IAS). Environmental education can play an important role in this process by providing relevant learning outcomes and experiences for youth and students, as well as professionals in different sectors associated with introduction pathways or who are involved in mitigation and eradication of IAS. This paper responds to the urgent call for the inclusion of the IAS topic in education through the development, implementation and evaluation of novel and user-friendly educational materials. The aim of this paper is to describe best practices in IAS education and to share the lessons learned from eight educational projects from seven different countries. We discuss four challenges for IAS education, related to (1) inconsistent and ambiguous terminology, (2) communicating risk, (3) implementation of education materials, and (4) evaluation of learning effects. Examples of best practices are the use of smartphone applications and gaming elements, place-based education and exhibitions. We also note the importance of open access publishing of education materials to make them easily available. We intend this discussion to serve as a source of inspiration to researchers, science communicators and teachers and to spur the development of new teaching materials worldwide.

One of the great challenges with invasive alien species is deciding how to act when a new invasive population is detected. This is partly due to a variety of diverse perspectives on risk perception, objectives, predicted effectiveness of different management actions and uncertainty in likelihood of success for each action. These differences of opinion are largely due to divergent perspectives and experiences among individuals or agencies, and can be overcome with careful consideration, consensus-building and collective action. Structured decision-making (SDM) is a formal method to identify shared goals and facilitate discussion among diverse participants with an aim to collaboratively achieve an outcome in natural resource management. While SDM is used by many agencies to deal with a spectrum of natural resource decision problems, other agencies do not use this process. This article acts as a primer on SDM, discussing key considerations relevant to each step. We reinforce these steps by reporting on a case study using SDM. The problem we address is a non-native smallmouth bass (Micropterus dolumieui Lacépède, 1802) population discovered in Cultus Lake, British Columbia (BC), Canada, in 2018. Smallmouth bass are invasive to BC, and while they may provide a unique and satisfying experience for recreational fishers, they may also exert high predation rates on at-risk sockeye salmon Oncorhynchus nerka and coastrange sculpin Cottus aleuticus endemic to the lake. We report on early successes to this process and how it fostered collaboration and collective action to begin the process of population control for this invasive smallmouth bass population.

The introduced monogenean Gyrodactylus salaris (Malmberg, 1957) is categorized as one of the most severe threats against Atlantic salmon (Salmo salar Linnaeus, 1758) in Norway and has almost eradicated salmon populations in the Skibotn and Signaldalen Rivers in northern Norway. The parasite was unintentionally introduced to the Skibotn River in 1976 via release of infested Atlantic salmon smolt from Sweden. The parasite is restricted to freshwater, and survives at most a few days without its host. Therefore, eradication of all hosts in the infected river systems has been the preferred strategy to eliminate the parasite. After two failed eradication attempts in 1988 and 1995, the parasite spread further to neighbouring rivers. This, along with several other failed rotenone treatments in Norway in the 1990s, resulted in severe criticism of the national eradication strategy for G. salaris. Still, the eradication program continued, and the failed eradication attempts were analysed for possible improvements. Arctic char (Salvelinus alpinus Linnaeus, 1758) has proved to be a potential long-term host for the parasite and infested char were documented to have survived in small, groundwater-fed tributaries and ponds during the first two eradication attempts in the Skibotn River. Low limits on allowed rotenone concentrations set by the pollution control authorities might also have contributed to the failures. A third attempt at eradicating the parasite from River Skibotnelva was made in 2015 and 2016, using new knowledge about the parasite and its hosts, renewed strategies to map and deal with dilution from groundwater intrusion and an official acceptance of increased concentrations of rotenone. Treatments for two consecutive years was the main strategy improvement from previous eradication attempts. Water samples showed sufficient levels of rotenone concentrations at all sample points during the treatment periods. Significant efforts in collecting all possible surviving fish from the first-year treatment and screening them for G. salaris revealed no surviving parasites at the time of the second-year treatment. The national G. salaris eradication campaign includes a surveillance programme for eradication confirmation. The results so far are positive for the Skibotn Region, but the earliest an eradication confirmation can be issued earliest is 2021.

Invasive aquatic plants can disrupt native biodiversity with considerable ecological impacts. Glyphosate-based herbicides provide one effective option to manage invasive macrophytes, but the variation in glyphosate sensitivity and accumulation in both target and non-target macrophytes is unclear. We performed an outdoor microcosm concentration-response study in which we applied seven glyphosate concentrations (0.1–8% of the Roundup WeatherMAX® formulation, corresponding to 0.5–43.2 g L^-1 glyphosate) in order to compare sensitivities and accumulation amounts of glyphosate and aminomethylphosphonic acid (AMPA; one degradation product) within and among two invasive emergent plants in North America (Phragmites australis and Typha × glauca), plus a native co-occurring plant (Typha latifolia) over a period of 27 days. Phragmites australis (dose lethal to 50% of the plant population, LC50 = 0.34 ± 0.03%) exhibited four to five times higher glyphosate sensitivity than T. latifolia (LC50 = 1.37 ± 0.13%) and T. × glauca (LC50 = 1.70 ± 0.17%). Invasive T. × glauca and native T. latifolia exhibited a similar glyphosate response, although individual variation was high within both taxa. 27 days after treatment with 5% glyphosate, a concentration that mimics many real-world applications, P. australis retained more glyphosate (348 ± 27 mg kg^-1 dw) than either T. latifolia (102 ± 20 mg kg^-1 dw; P < 0.001) or T. × glauca (92 ± 12 mg kg^-1 dw; P < 0.0001). Our results suggest that glyphosate response varies among and within emergent aquatic macrophyte taxa, independent of taxon invasiveness. When the goal is to minimize glyphosate exposure of the environment, managers could consider variation in glyphosate response at both individual and taxonomic levels. Moreover, managers should be aware that glyphosate accumulates in macrophytes.

The New Zealand mud snail (NZMS) Potamopyrgus antipodarum, is an invasive species of freshwater snail that has become established in the United States. Where they establish, NZMSs can achieve very high densities and have negative ecological impacts. The discovery of NZMSs at Page Springs Hatchery (PSH) in 2019 triggered a need for treatment options in a hatchery that would not result in eradication of fish stocks. The effects of a low-dose (30 ppb) treatment of EarthTec® QZ on NZMSs, Page springsnails Pyrgulopsis morrisoni and pond snails Physella virgata were evaluated for 39 days. Pond snails fell to zero live individuals 15 days before NZMSs, which fell to zero live individuals 36 days into treatment. Page springsnails fell to zero live individuals three days after NZMSs. It appears that EarthTec® QZ may be an effective treatment for NZMSs under the conditions tested within PSH. Additional testing needs to be performed to evaluate the potential effects on other non-targets under varying environmental conditions.

Zequanox® is a biopesticide registered by the U.S. Environmental Protection Agency (USEPA) and the Canadian Pest Management Regulatory Agency for controlling dreissenid mussels with demonstrated selective toxicity. However, some research has indicated that Zequanox may impact the body condition and survival of some non-target species. We assessed avoidance behaviors of two species of cold-, cool-, and warm-water fishes to Zequanox at the maximum concentration allowed by the USEPA label (100 mg/L as active ingredient). Naïve, juvenile fish (n = 30 per species) were individually observed in a two-flume choice tank through which Zequanox-treated and untreated water simultaneously flowed in an unobstructed arena. Individual fish were observed during an untreated control period (20 min) and two Zequanox-exposure periods (20 min each). Treatment was alternated between arena sides to account for potential side bias in the test subjects. Positional data were collected and tabulated in real time with EthoVision® XT software. Zequanox concentrations and water quality properties (pH, dissolved oxygen, temperature, and specific conductance) were monitored during each trial. Analysis of treatment response was performed using a contrast within linear mixed-effects models. Our results indicate that Brook Trout, Lake Trout, and Bluegill avoided Zequanox-treated water, Yellow Perch were indifferent to Zequanox-treated water, and Lake Sturgeon and Fathead Minnow were attracted to Zequanox-treated water. These results combined with existing species sensitivity literature may help inform resource managers of potential treatment-related risks.

This work evaluates technological strategies that include conventional vessel-based and alternative barge-based technologies to meet various treatment standards and combinations. We construct a vessel-versus-barge compliance cost framework informed by California efforts to provide additional protection from ballast discharge invasive risk. The technology-policy goal is to achieve the regulatory standards with appropriate technology, and meanwhile, minimize the compliance cost to reduce the burden on the shipping industry. The results show that the required numeric standards matter a lot. If a single global standard is a weak standard, then adopting vessel-based compliant technology is less costly than centralized barge-based compliance. We consider these findings to apply generally beyond the California context. Specifically, if some region or all regions adopt standards different from current global standards (i.e., stricter), barge-based systems can be less costly than retrofitting world fleets. The findings reveal the potential role of barge-based treatment measure. The increased $0.7 billion compliance cost for the U.S. to achieve stricter ballast water regulation per year may inform the relevant policymakers.

An array of vectors have been identified that pose a risk of spreading invasive alien species (IAS), from personal protective equipment to large equipment such as vehicles and boats. Biosecurity practices that remove and/or kill IAS reduce the risk of accidental spread. The effectiveness of biosecurity protocols suitable for large equipment is little tested and requires development. One widely-used biosecurity method for large equipment is high-pressure hot water spray machines. This study tests the effectiveness of high-pressure hot water spray to induce mortality in two invasive aquatic plants: floating pennywort (Hydrocotyle ranunculoides) and Australian swamp-stonecrop (Crassula helmsii); and two invasive invertebrates: killer shrimp (Dikerogammarus villosus) and zebra mussel (Dreissena polymorpha) in field conditions. IAS were exposed to hot water spray for a range of durations (5–15 seconds) and from a range of distances (10–30 cm). Further treatments of up to 90 seconds were applied to C. helmsii. Complete survival of D. polymorpha, D. villosus and C. helmsii was seen in all control treatments following exposure to cold water spray. Hot water spray caused complete mortality of D. polymorpha and D. villosus at 10 cm for 15 seconds, demonstrating the effectiveness of the hot water treatment in inducing mortality. However, treatments were less effective when applied at longer distances and shorter durations. In contrast, hot water spray was ineffective in causing mortality in C. helmsii, even at 90 seconds of exposure. Fragmentation and complete mortality was seen in H. ranunculoides following exposure to hot and cold water spray, therefore the pressure of the spray was associated with H. ranunculoides mortality. The use of hot water spray is effective against the aquatic invasive animals tested here, however to ensure complete mortality, the importance of both duration and distance of hot water spray application is highlighted. Hot water spray did cause complete mortality in H. ranunculoides but not in C. helmsii, therefore the need for treatment water containment and safe disposal is paramount to prevent spread of potentially viable propagules.

Decontaminating recreational watercraft, and fishing, sailing or watersports equipment after use can reduce the overland dispersal of aquatic invasive species (AIS) among lakes. Recommended methods include pressure-washing, rinsing with hot water, using cleaning agents, or air-drying, but the extent of their efficacy is unknown. The aim of this review is to assess the effectiveness of current decontamination measures for recreational watercraft against various AIS. Web of Science, Greenfile, Environment Complete and Geobase were searched for articles published through September 2019. Studies on preventing overland AIS spread, and plant and invertebrate AIS response to hot water, pressure-washing, desiccation or cleaning agents, were selected. Of 37 studies included in the review, the majority (70.3%) assessed air-drying, followed by hot water (32.4%), household chemicals (16.2%), and pressure-washing (2.7%). The recommended air-drying duration of up to one week produced high mortality (≥ 90%) among several invertebrate and macrophyte species, although survival was high for certain aquatic snails. Larger and/or older invertebrates were more resistant to desiccation. Aquatic plant survival and growth were inversely related to water loss (a function of drying time and relative humidity), and short or single fragments were less resistant to air-drying than larger or clustered fragments. Immersion in water ≥ 50 °C for 15 minutes resulted in 100% mortality among mussels, small invertebrates and some plant species. A higher temperature of 60 °C was required for hot water spray applications lasting ≥ 5 seconds to achieve the same mortality rate among dreissenid mussels. High pressure-washing eliminated significantly more entangled plants, and small organisms and seeds than low pressure. Household chemicals such as salt or bleach required specific doses and immersion durations to be lethal to small organisms. This review reveals that current decontamination methods may be effective, but their efficacy against a diversity of AIS, including those on watch lists, are not yet well-understood. As the literature is currently skewed towards studies on air-drying, which has limited efficacy, further research is required to evaluate practical, and alternate or combined measures to best inform management practices.

The ability to produce byssal threads enables invasive dreissenid mussels to attach to recreational boat hulls and other equipment. These mussels can be exposed to air during overland transport of recreational boats, which affects their potential to survive transport. Survival during air exposure is determined by a variety of environmental factors such as temperature, relative humidity, shaking and vibrations and the movement of air. This study assessed the influence of air movement on the survival and behavioural changes of the quagga mussel (Dreissena bugensis). Survival time decreased significantly when mussels were exposed to a wind speed of 10 and 50 km.h^-1 compared to standing air survival. Mussel clumps survived significantly longer than mussel individuals. The lethal time of 99% of mussel individuals (LT₉₉) decreased from 29.26 to 18.24 hours when exposed to a wind speed of 50 km.h^-1. At a wind speed of 10 km.h^-1 LT₉₉ survival times of mussel clumps (26.94 h) were higher compared to individual mussels (19.76 h). Valve gaping behaviour changed when mussels were exposed to flowing air. Mussels exposed to a wind speed of 10 km.h^-1 were on average open for 6.41% of the time, whereas in standing air mussels were on average open for 26.78% of the time. These results indicate that air movement has an influence on the survival potential of aerially exposed quagga mussels. Management of invasive alien mussels should take into account that the quagga mussel can survive air exposure with an wind speed of 50 km.h^-1 over 18 hours when attached to boat hulls. 50% of the mussels can be transported alive for distances over 300 km and 1% of the mussels can be transported alive for more than 900 km. Decontamination of boats and associated equipment will be vital for improved spread-prevention of invasive mussels.

The release of live organisms into the environment by Buddhists for religious reasons, known as “life release”, is a less understood pathway of biological invasions. To better understand the activity as it is practiced in the United States, we contacted more than 400 Buddhist groups and interviewed 11 individuals during late 2018 and early 2019 to discuss the practice. The information obtained from this small sample included the nature of the ritual, their awareness of impacts and legality, potential low-risk alternatives to the practice, and how to best engage with this community moving forward. Practitioners’ motivation and understanding of the practice are similar to previously published work, though with perhaps a stronger emphasis on saving lives. Practitioners use release animals that they believe are likely to survive, not harmful to the local environment, and are easy to obtain, including earthworms, crickets, and minnows. Release events are often held in places that give the animals the best probability of surviving and group release events are held in public spaces that may allow for fellowship afterwards. Practitioners were generally aware of potential negative impacts of the practice and the legality of the practice. With this in mind, it was often mentioned that effort was put into limiting these impacts. Promisingly, the interviewed practitioners thought more environmentally friendly methods of release were possible and would welcome further engagement with natural resource professionals and Buddhist opinion leaders to practice life release in an environmentally sustainable manner.

Since the 1950s, nine alien crayfish species have been introduced in the Rhine-Meuse river delta. Seven species originate from North America, one from Southeast Europe and one from East Europe/Asia. Currently, at least seven species have well-established populations. Five species are listed as invasive alien species (IAS) of European Union (EU) concern (i.e. Faxonius limosus, Faxonius virilis, Pacifastacus leniusculus, Procambarus clarkii and Procambarus virginalis). All crayfish species of EU concern are subject to restrictions on keeping, transportation, importing, selling and breeding. Member States are required to take action on pathways of unintentional introduction, to perform measures for early detection and rapid eradication of these species, and to manage species that are already widely spread. The impact of these IAS on biodiversity and functioning of ecosystems mainly results from transmission of the crayfish plague pathogen Aphanomyces astaci, predation on native fauna, and fragmentation and consumption of aquatic plants. Moreover, burrowing activities of some IAS cause bank instability, increase risk of dike breaches in peatland areas and enhance sedimentation rates in ditches and canals. First-line risk assessments for the Rhine-Meuse river district with the Harmonia+ scheme shows that seven crayfish species have a high risk of impact on biodiversity, water safety and ecological status of water bodies. Four species have already established populations in this area of concern. The risk of spread via interconnected rivers, canals and small watercourses is high for all species of North American origin. Eradication of alien crayfish populations in an extensive and open network of interconnected watercourses is not feasible. Six management strategies for control of alien crayfish species were formulated. These strategies were assessed using various criteria for cost-effectivity and subsequently prioritized using an unweighted Multi Criteria Analysis. Feasible strategies for population control of invasive crayfish species combine a) measures for enhancing robustness and resilience of ecosystems, and b) crayfish trapping by commercial fishermen, water authorities and well-informed citizens.