Invasive species are a major driver in the global decline of biodiversity. Invasive herpetofauna cause ecological harm through different mechanisms that vary in scope and severity, and Florida boasts more established nonnative herpetofauna species than any other region in the world. There, black spiny-tailed iguanas (Ctenosaura similis) are one of several large invasive reptiles known to occupy the burrows of the imperiled, native gopher tortoise (Gopherus polyphemus) and may even exclude tortoises from their burrows. To test the hypothesis that iguanas exclude tortoises from their burrows and evaluate effectiveness of iguana management, we conducted a field study on Gasparilla Island, Florida, USA. We used a burrow scope to estimate occupancy of each species within tortoise burrows at sites with and without sustained iguana removal efforts and modelled co-occurrence patterns between the two species. We used two-species occupancy analyses to test three predictions relating to gopher tortoise burrow use; 1) that tortoise occupancy within burrows would be lower given the presence of iguanas, 2) that iguana occupancy would be positively associated and tortoise occupancy would be negatively associated with the presence of iguana side-tunnels within a tortoise burrow, and 3) that iguana occupancy would be lower and tortoise occupancy would be higher at sites with ongoing iguana removal. Our results support the hypothesis that gopher tortoises are less likely to utilize burrows that are or have been utilized by black spiny-tailed iguanas. We estimated the probability of tortoise occupancy conditional on iguana presence to be 63% lower than tortoise occupancy conditional on iguana absence. Our results also show that sustained iguana removal is likely effective at reducing iguana occupancy of tortoise burrows, as the probability of iguana occupancy was 72% lower where iguanas are actively managed.

Effective control of invasive pests primarily occurs through accurate monitoring of their populations. Precisely planned monitoring allows us to use citizen science to conduct experiments over a large monitoring area. Within the framework of the NAJDI.JE project, an experiment was carried out with the involvement of the general public at 55 sites in 10 regions of the Czech Republic. Two-thirds of the participants (37) tested a treatment with yellow sticky traps (YSTs) only, and one-third of the participants (18) tested YSTs together with insecticide spraying. Most locations were in the South Moravian region, where R. completa first appeared in the Czech Republic and where it is currently causing the greatest nut damage on walnut trees. In our trial, the use of three YSTs per site with bi-weekly monitoring was found to be as effective as ten traps for detecting the infestation. Another very valuable novel finding was that the height at which the YSTs were hung was not a significant factor in the number of adult R. completa captured in the canopy. Our recommendation for simple and accurate monitoring of R. completa is to hang three YSTs at a height of 2 m from the ground evenly around the perimeter of solitary trees in gardens.

Oxbow lakes are highly productive waterbodies that host multiple life stages of many freshwater aquatic species. These lakes also provide foraging and rearing habitat to the invasive silver carp (Hypophthalmichthys molitrix) enabling populations to grow in biomass and abundance that can add propagule pressure to connected waterways and oxbows within the Mississippi River Basin. Ecologically these fish are undesirable because they overlap in diet and may compete for resources with native fishes and negatively impact recreational fisheries. Our goal was to evaluate silver carp distribution patterns in a major Mississippi River oxbow lake to inform removal programs and precision harvesting. We implanted 35 adult silver carp with acoustic tags and released them into the lake. Periodic tracking over 365 d revealed that fish were predominantly found in lake areas with water depths ranging from 2.0 to 5.9 m during all seasons, despite the availability of shallower and deeper water. Silver carp tended to aggregate in the wintertime (December–February) relative to other seasons. This information about lake area uses and seasonal aggregations could inform removal efforts in invaded waterbodies by exploiting natural behavioral and temporal vulnerabilities of this highly invasive and difficult-to-capture fish.

Invasive grass carp Ctenopharyngodon idella spawning was confirmed in Lake Erie with the collection of fertilized eggs in the Sandusky River, Ohio in 2015. Managers responded with initiation of adult grass carp removal in 2017. Hydrodynamic modeling revealed a potential spawning location in downtown Fremont, Ohio (41.3455; −83.1110), which was supported by the presence of sexually mature adults. Egg detection and adult removals appear to coincide with periods of elevated discharge and suitable water temperatures. Electrofishing is the primary method for removing adults during spawning, however, it is unknown if this has indirect effects such as disruption of grass carp spawning; thereby lowering egg presence in ichthyoplankton samples. We used a binomial generalized linear model to predict the probability of grass carp egg presence (≥ 1 egg) in a paired ichthyoplankton net based on the presence of electrofishing in the spawning grounds and net depth using 2017–2022 data. Further, we carried out a field experiment to isolate the effect of electrofishing by sampling eggs at two sites before and during electrofishing in the spawning grounds in 2022. Analysis of 2017–2022 egg and electrofishing data suggested that grass carp egg presence in a paired ichthyoplankton net was significantly higher without electrofishing and in nets towed at a depth of 1.5 m compared to surface-towed nets. Data analysis from the field experiment revealed a significant negative relationship between electrofishing in the spawning grounds and grass carp egg collections downstream. Both analyses suggested lower egg capture rates associated with electrofishing in the spawning grounds, although other factors should be further quantified. Consequently, electrofishing may cause a short-term disruption in grass carp spawning in the Sandusky River and could reduce spawning during preferred conditions.

Redbelly tilapia (Coptodon zillii) poses a significant threat to aquatic ecosystem security and water quality, severely impeding ecological restoration efforts for the aquatic ecosystem. But effective control methods for redbelly tilapia, particularly within riverine and lacustrine habitats, have been scarce. “Miefeiling” an organophosphorus pesticide, has demonstrated specificity as a piscicide for tilapia species. However, there was little information regarding the application of this compound in natural water bodies, such as lakes. This study aimed to evaluate the efficacy and safety of “Miefeiling” in Dongshan Lake of Guangzhou City, where redbelly tilapia constituted 79.41% of the biomass of all the fish species. A concurrent control experiment was conducted in ponds. The application of “Miefeiling” at a concentration of 0.20 ml/m³ resulted in a substantial reduction of the redbelly tilapia population within a 30-hour period, achieving an eradication rate of 88.7 g/m³ and totaling 1598.2 kg of the redbelly tilapia removed from Dongshan Lake. Post-treatment population dynamics were as follows: no redbelly tilapia was detected 20 days post-treatment; 180 days post-treatment, redbelly tilapia accounted for 7.22% of the fish biomass; and 630 days post-treatment, comprised 14.03% of the fish biomass. This was significantly lower compared to the control lake without piscicide application, where redbelly tilapia made up 75.43% of the fish biomass. Additionally, total phosphorus and chemical oxygen demand levels reverted to baseline within seven days, with no detectable presence of malathion or dichlorvos throughout the experimental period. The application of “Miefeiling” did not adversely affect other native fish species, and the pond experiment indicated minimal impacts on phytoplankton and water quality. These results suggest that “Miefeiling” can effectively eradicate redbelly tilapia without compromising water quality and the native biota in the lake.

Monitoring programs or surveys for marine alien species in biofouling assemblages often focus on surveying after a specific period of settlement, with few regions being able to implement ongoing monitoring systems. Whilst these programs are beneficial, they provide only a snapshot in time and may miss key information about the temporal settlement patterns of alien fouling species and the associated management implications. The current study initiated a temporal settlement study that could 1) track the settlement patterns of fouling species with a focus on detecting alien species and 2) highlight the change in community structure across different months, providing an insight into the ecological succession. The study was conducted in a marina in Cape Town, South Africa, using PVC settlement plates, and serves as a baseline for a longer-term monitoring settlement study. The findings indicate that the species richness and abundance differed significantly across the months (Wald test: p < 0.001), with a rapid increase in both measures within a month and a gradual decline in species richness after two to three months. A total of 12 alien species were detected accounting for 55% of the community structure. Within the first month, eight of those species had already settled. Overall, four species (Corella eumyota, Diplosoma listerianum, Neodexiospira brasiliensis and Balanus trigonus) were particularly dominant throughout the study. The ascidian, Corella eumyota currently listed as native, was one of the first species to settle and demonstrated strong competitive traits, raising concerns about its current status in the region. The findings highlight the value of temporal settlement studies revealing patterns that may have been overlooked when sampling at only one point in time. Thus, a longer-term monitoring program that tracks the temporal settlement patterns of alien fouling species could start to provide valuable insights to management authorities.

U.S. Laker ships move large quantities of untreated ballast water from the lower Great Lakes to Lake Superior, making early detection of AIS in harbors of ballast uptake critical to spread prevention. Environmental DNA (eDNA) techniques using qPCR methods targeting AIS of concern can facilitate early detection surveillance by signaling presence of the target species. However, such methods detect genetic material of an organism regardless of the organism’s vital status, making the question of how long eDNA persists in the environment after removal or death — a duration known to vary across species and conditions — highly relevant to interpretation of eDNA screening outcomes, with implications for invasion management and action. While eDNA decay rates have been measured in closed systems under varying conditions for organisms easily removed from the system, data are lacking for zooplankton since removal experiments are not practical. We developed a method that utilizes microcosms to measure eDNA signal decay in zooplankton after the death of the organisms and applied the method to persistence of target-specific, qPCR signal in eDNA extracted from Lake Erie water microcosms inoculated with the invasive mysid, Hemimysis anomala (GO Sars, 1907). At temperatures between 19 and 23 °C, qPCR signal rapidly decayed in the first 48 hours. During the exponential decay phase, T90 and T99 values were 14.8 hours and 29.5 hours respectively, the eDNA half-life was 4.5 hours and the decay rate constant was 0.154 h^-1. The limit of detection was reached in seven days and there was no detectable signal for the remainder of the 29-day experiment. Similar to what others have shown for larger organisms, these results indicate that eDNA from this species of zooplankton is rapidly metabolized and support the use of screening for eDNA as a valuable tool to enable early detection of new populations in Great Lakes harbors. .

Eleven species of Erythraean alien decapod crustaceans were identified in the fouling communities collected between 2021 and 2023 from Autonomous Reef Monitoring Structures (ARMS) stationed along the Mediterranean coast of Israel, of which, three are new records for the Mediterranean Sea: Athanas dimorphus Ortmann, 1894, Pilumnus longicornis Hilgendorf, 1879, Pilumnus savignyi Heller, 1861; additionally, two are new records for the Israeli coast: Sphaerozius nitidus Stimpson, 1858, and Liomera rugipes (Heller, 1861). The results substantiate the role of marine infrastructure as steppingstones for fouling-associated alien species. As Israel advances the construction of littoral, shelf, and off-shore maritime infrastructure, it is essential to address the shortcomings in its existing National Monitoring Program. A comprehensive and standardized monitoring system must be implemented to enable the timely detection of invasive fouling taxa. The deployment of ARMS arrays has been established as a fundamental approach in achieving this objective, and serve, in addition, as a Mediterranean-wide early warning system.

ORMEF, accessible at https://www.ormef.eu, is a new interactive web platform that consolidates a vast historical repository of georeferenced records of exotic fishes, extracted from scientific literature. Covering observations spanning over a century, from 1896 to the present day, ORMEF incorporates 12,553 georeferenced occurrences distributed across 221 fish taxa, meticulously sourced from 805 scientific papers. This paper outlines the architecture of ORMEF and provides an insightful illustration of its tools and future developments. As an authoritative yet user-friendly reference, ORMEF has the potential to make a substantial impact across various initiatives. From advancing scientific research and supporting conservation efforts to engaging communities, ORMEF’s outputs and data offer promising applications not only for marine bioinvasion research but also for informed decision-making at both the Mediterranean and EU levels.

The literature indicates that the wading gear of recreational anglers is the main vector of transport of the aquatic invasive species, New Zealand mudsnail Potamopyrgus antipodarum within and between rivers. We surveyed 308 anglers fishing the Pere Marquette River, Michigan, USA in 2016–2017. Of these anglers, 44% reported that they cleaned their waders between fishing trips. Even though 52% of anglers were aware of NZMS, there was not a significant difference in wader cleaning behaviors between anglers aware or unaware of NZMS, indicating that outreach efforts need to focus beyond the awareness stage. We provide a flowchart to help guide outreach efforts given the different stages of angler awareness and knowledge, as well as their propensity to engage in wader cleaning. As no in-stream method of treatment is presently available, angler social behavioral change should be a focus of future management efforts.

Producing prioritised lists of current and prospective non-indigenous species with the potential to cause significant harm is essential for several reasons but these need to be transparent both in the methods used and their justifications. Despite their varied applications, the criteria and components used to generate priority lists for non-indigenous species are often not indicated and there are no universal guidelines for their development. As such, we conducted a literature review identifying the common elements of existing priority lists to develop a framework, including considerations, to guide the creation of future priority lists for non-indigenous species. This framework is organised around five elements: (1) Scoping, (2) Compilation of a Master List, (3) Primary Assessment, (4) Secondary Assessment, and (5) Listing. Using the framework and associated flowchart, end users identify the considerations most relevant to their objectives so as to ascertain the specific criteria and parameters required to develop priority lists that are defensible and fit-for-purpose. This framework is designed to be applicable for a variety of purposes, is taxa and ecosystem-independent, and when implemented in a transparent way, will improve clarity for interpretation of, and comparisons across, priority lists, resulting in more widespread acceptance of lists among end users and stakeholders.

The impacts of invasive aquatic plants (IAPs) are well documented and extensive relative to other functional groups of invasive species. Operational control of IAPs has evolved from a limited range of general biocides and physical control methods to the development of more targeted methods that offer more selective control measures. Despite the increase in IAP control strategies, several studies have identified the need to better serve IAP managers through identification and implementation of control-related research needs. Successfully aligning research needs and management products requires consulting with all interested parties to develop research questions and engagement of managers interested in adaptive management in the research programs. To this end, it is vital to use a process in which ecologists, practitioners, and decision-makers work collaboratively to develop scientific research, a process known as translational ecology. We identify IAP control-related research needs through a combination of species-specific literature reviews and an expert elicitation workshop for 20 priority IAP. Based on the literature reviews and workshop, generalized research needs, species-specific research needs, and an analysis of factors related to tool availability were developed. While the scope of this case study is the Great Lakes region, the IAPs and associated research needs discussed in this study are relevant to researchers studying these globally invasive species anywhere within their invasive range and should be used to inform research wherever it is undertaken. These findings will help agencies and academic institutions to plan future research activities and project proposals and serve as a reference document to inform funding agencies as they make decisions related to invasive aquatic plant control and research.

Government efforts to address invasive alien species (IAS) need collective actions, cooperation, and pooling of resources and expertise across borders. What is the status of transnational collaboration in the European Union (EU) to address IAS? First, IAS management projects within the EU were identified by a systematic literature review. Second, role players’ perspective on transnational collaboration was investigated through a questionnaire. Third, challenges and opportunities were explored in an engagement workshop. This paper shows that language barriers and limited public access to information on IAS management across the EU have resulted in the work of competent authorities being little recognized by research projects and EU-funded initiatives. Our findings highlight that while there is a growing transnational consciousness, transnational projects are more academic in nature rather than involving direct collaboration between competent authorities. Finally, this paper advocates for policy agendas endorsing the gaps identified in protocols, plans and chains of actions necessary for effective management of IAS.

GuardIAS is a three-year Horizon Europe project starting in January 2025, uniting diverse expertise to address aquatic invasive alien species (IAS) management. This multidisciplinary initiative comprises seven interconnected work packages targeting all invasion stages (pre-border, border, post-border) to develop tools for disrupting invasions. GuardIAS will employ Artificial Intelligence and data workflows to enhance biodiversity databases with species distributions, environmental tolerances, traits, and genetic information, thereby improving the European Alien Species Information Network (EASIN) and harmonizing key datasets. The citizen science platform iNaturalist will be enriched with expert-verified images of aquatic IAS for early detection and monitoring of geographic spread. An Early Warning System focused on IAS of EU concern will be developed and integrated into EASIN. To prevent hull biofouling—a major IAS introduction pathway—GuardIAS will explore nanotechnology-based antifouling coatings. The project will also investigate recreational boat movements along European coastlines, an understudied factor in IAS secondary dispersal. An eDNA reference library and assay panel will be developed for effective IAS detection. Advanced models, such as the Nobel Prize winning Multi-Region Input-Output analysis, will assess IAS risks, including impacts on threatened species and critical habitats under current and future scenarios. Systematic conservation planning tools will prioritize IAS monitoring and management actions based on their impacts. GuardIAS will enhance data collection, monitoring, early detection, and public awareness through innovative citizen science initiatives like BioArtBlitz events — where arts serve as a communication vehicle — eDNA sampling, sound analysis projects on Zooniverse, and marina events for boaters. Stakeholder engagement will be fostered through applied games. Collaborating with environmental authorities, industry, and aquatic managers, the project will co-design and implement eradication and control efforts in marine and freshwater environments. By integrating Social Sciences and Humanities, GuardIAS will promote collaborative knowledge creation, understand public perceptions on IAS management, and facilitate exploitation of the project’s outcomes.