In its 120-year history, the major injurious wildlife provision of the Lacey Act has remained nearly intact. The purpose of the Federal law has always been to protect the United States from the introduction of invasive and otherwise harmful species. Amendments along the way have transformed the law, sometimes narrowing and sometimes broadening. Here for the first time, the major changes to the injurious wildlife law from 1900 to the current law are compiled to provide a history that is critical to understanding how the nation’s oldest invasive species law has varied in its ability to prevent wildlife invasions. In 1900, under the oversight of the U.S. Department of Agriculture, the newly enacted law prohibited the importation of any foreign wild mammal or bird to protect agriculture and horticulture, with exceptions only by permit. A small designated subset of wild mammals and birds could not be imported under any circumstance, and these were the first injurious species. For almost a half century, little changed. The 1939 amendment transferred authority of injurious wildlife to the U.S. Department of the Interior, a change affecting little except the oversight. Then a 1948 amendment removed a critical clause. The deletion suddenly removed the prohibition on the importation of any wild mammal or bird, except for the designated injurious species, which were still unconditionally prohibited. In 1960, Congress expanded the injurious provisions of the Lacey Act (18 U.S.C. 42) by authorizing additional vertebrate and some invertebrate taxa that may be designated as injurious and by authorizing additional categories of interests that could be affected. Simultaneously, however, the unconditional prohibition for injurious species was replaced with a permit exception system, and the 1960 amendments have remained to this day. By presenting how the law varied over the decades, this history will allow scientists to determine the effectiveness of a law that is well into its second century.

The anthropogenic transfer of non-indigenous marine species (NIMS) into new areas of the oceans is a key issue. Despite increasing research effort in recent years many fundamental questions remain to be answered before we can effectively manage the issue. One question is whether the greater number of NIMS thus far documented in temperate waters is real or an artefact of fewer surveys being undertaken in tropical environments. Another one is whether poor taxonomic knowledge of the biodiverse tropics hides NIMS that actually occur there. Extensive taxonomic work in three Pacific localities (Guam, northern Western Australia and Singapore) has been collated in previous papers showing that there are relatively few NIMS in these biodiverse environments. The present paper replicates investigations for a low latitude environment in southern Florida in the Atlantic Ocean. The focus area includes the extensive Florida Keys coral reef environment, the southern margin of the Everglades on Florida Bay and the major PortMiami. Only 48 NIMS were identified in a literature-based compilation of 4,615 species; 15 species were represented by isolated records and have not established populations, leaving only 33 NIMS that are established or whose status is unknown. Records for Mollusca, the group with the most species (1,153) in the compilation, were individually researched and taxonomically verified. It is argued that the relative paucity of NIMS is not a straightforward temperature-driven tropical/temperate issue, but instead there are biological factor(s) restricting the ability of NIMS to colonise biodiverse environments compared to less diverse areas.

The management of some invasive plant species is difficult because species can exhibit high productivity despite control measures. Inefficient control methods may even produce unwanted side effects. We conducted an experimental study on Fallopia spp., a major invasive plant in Europe. We tested the effects of two different stem-cutting frequencies on the aboveground and belowground traits of several genotypes in a greenhouse experiment against control plants (no cuts). Plants receiving one cut per month for a total of 4 cuts experienced 30% mortality of the individuals, surviving plants had greatly reduced values of the measured traits, especially for biomass and height. In contrast, plants in the treatment group, consisting of a single cut in five months, were eventually able to compensate for the loss of aboveground parts despite reduced length and biomass of the rhizome. Our results indicate that minimal mechanical intervention has limited effects on Fallopia spp. During the vegetative season, managers can increase control efficacy through regular cutting rather than a one-time intervention for these species.

The zebra mussel, Dreissena polymorpha, has strong economic and environmental effects within a wide range of habitats, including reservoirs, and there is a need to monitor in advance of an arrival so that an elimination might be possible. We report the establishment of the zebra mussel in the Alfundão Reservoir, a small reservoir in central Portugal, 190 km away from the closest known population in Spain. The area has been monitored using suspended ropes since 2016, and during October 2019, mussels of 5–43.8 mm shell length were recorded for the first time in the Alfundão reservoir. The shallow lined reservoir was then chlorinated and drained. To date, this treatment appears to have been successful in eliminating this population. It is unknown how this mussel arrived, since the reservoir area has a surrounding exclusion zone.

The largemouth bass Micropterus salmoides (Lacépède, 1802) is a highly invasive freshwater species, and has a considerable impact on the diversity of indigenous aquatic organisms. We hypothesized that mature males released sex pheromones to attract mature females to their nests. To develop an effective method for controlling the population in a lake of northern Japan, we studied the efficacy of using bile collected from mature males with the bioactive function to attract mature females. A trap was devised to evaluate the attraction of sample solutions from males and to test practical uses of the pheromone. In the spawning season, when bile from reproductive males (RB) was introduced into the traps, female catches in the trap were significantly higher than when bile from non-reproductive males (NRB) or controls were used. In the non-spawning season, the female largemouth bass did not show any preference for RB. Other fish species did not show any preference for RB in both the spawning and non-spawning season. This study shows that RB contains a sex pheromone that attracts mature females, suggesting that pheromone traps could possibly be used to control largemouth bass populations.

Common Carp (Cyprinus carpio Linnaeus, 1758), is a highly invasive species that has had profound effects on biodiversity and ecosystem services. Many Carp management methods have been applied including physical removal, pesticide treatments of whole lakes, and water drawdowns. Herein, we tested key elements of a potential “bait and switch” approach in which corn could be used to induce feeding aggregations of Carp and then switched for corn pellets with a pesticide Antimycin-A (ANT-A) to selectively target the Carp. First, laboratory experiments were used to determine if addition of lethal concentrations of ANT-A to corn pellets deterred Carp from eating corn-based food pellets. Second, a pond experiment tested if a corn-based bait containing ANT-A functioned as a species-specific Carp management tool in a semi-natural environment with three common native fishes: White Sucker (Catostomus commersonii Lacepède, 1803), Yellow Perch (Perca flavescens Mitchill, 1814), and Bluegill (Lepomis macrochirus Rafinesque, 1819). The use of baited sites by Carp and native species was monitored using passive integrated transponder (PIT) tags. Mortality of each species and presence of corn in their digestive tracts was also monitored. Our laboratory experiment showed that presence of ANT-A did not deter Carp from consuming the pellets. The pond experiment showed that only Carp perished in significant numbers once toxic bait was applied. Further, only Carp increased their use of baited sites once baiting began, and only Carp had corn in their digestive tracts. Overall, our results indicate that corn might function as a species-specific Carp attractant in systems of North American Midwest and that corn-based bait can be used to effectively conceal a lethal dose of ANT-A. Further research is necessary to refine this potential management tool, specifically investigating the behavioral and social dynamics of Carp aggregating at sites baited with corn to enhance the temporal and spatial specificity of pesticide application.

There is a critical need to identify and develop behavioral deterrents that impede the spread of invasive Bigheaded Carp (Hypophthalmichthys spp.) through waterways in North America. High-intensity light has significant advantages over other behavior deterrents because it can be relatively inexpensive, easy to deploy and can be used in shallow waterways. Although previous studies have shown that light has the potential to guide and block the passage of fishes, the efficacy of light has also been found to be species- and situation-specific, and no study has yet examined how well light works for Bigheaded Carp. The present laboratory study sought to determine whether high-intensity white light might be effective at blocking Bighead Carp (H. nobilis) while having minimal effects on another model fish species. We measured the response of juvenile Bighead Carp and Largemouth Bass (Micropterus salmoides) to three types of high-intensity white light (constant light [0 Hz] and strobing light [5 Hz or 12 Hz]) in both a dark [1 lux] and a dimly-lit [100 lux] laboratory flume. High-intensity light consistently blocked at least 74% of Bighead Carp in a dark flume, with strobing and constant light having equivalent effects (p > 0.05). In contrast, a constant light (80%) was more effective than a 5 Hz strobing light (33%) in a dimly-lit flume (p < 0.05). While Largemouth Bass were also blocked by constant light (63%) in a dark flume, both a 5 Hz (82%) and 12 Hz (88%) strobing light were more effective (p < 0.05). When tested in a dimly-lit flume, Largemouth Bass were not blocked by either the constant light or a 5 Hz strobing light (p > 0.05). Taken together, our experiments demonstrate that responses to light can be species- and situation-specific, and that high-intensity constant light has particular promise to block Bighead Carp in both dark and dimly-lit environments without strongly blocking bass. Light might be especially useful in shallow, clear waters that cannot be blocked by other means.

Several species of small invasive lizards form high densities in their invaded ranges and threaten native biodiversity in a variety of ways. Little attention has, however, been devoted toward identifying tools to control populations of these lizards for conservation purposes. Some of these invasive lizards or their close relatives consume a variety of sweet food items, either natural or human-made. Thus, we conducted experimental laboratory trials to identify the potential for sweetened solutions, pastes, or fruit products to serve as attractive baits for two invasive lizard species, and we evaluated the potential effectiveness of acetaminophen and alpha-chloralose to serve as toxicants when mixed in such baits. Using paired-choice tests, we identified red baits (as corn syrups, sweetened pastes, or strawberries) as the most effective baits for Anolis carolinensis and white corn syrup as the most effective bait for Hemidactylus frenatus. Bait attractiveness was improved by the addition of vanilla flavoring. We assessed the LD100 of acetaminophen and alpha-chloralose to A. carolinensis, H. frenatus, and Lampropholis delicata by oral application of solutions of known concentration. Acetaminophen proved infeasible for use as a toxicant in sweet baits because of its low aqueous solubility and high concentrations needed to attain lethality; alpha-chloralose was more successful in this regard because of its greater toxicity and smaller quantities needed for use. However, keeping the toxin in suspension remains a problem. Trials combining alpha-chloralose with some of the more effective baits provided some degree of lethality among samples but indicated that further work is required in order to identify the best bait matrix for control projects in a field setting. We recommend next steps to advance development of an effective toxicant+bait system for controlling small invasive lizards that build off our results.

The opening of the Suez Canal in 1869 created a tremendous impact both on the shipping industry, by shortening navigational routes, and on ecological communities in the Mediterranean Sea, by facilitating numerous introductions of non-indigenous species (NIS). These impacts are deeply intertwined as the majority of Mediterranean Sea introductions are ship-facilitated. Here we analyzed shipping data for the Canal between 2011–2018, and characterized the shipping trends of the Canal in relation to global shipping trends and to the introduction of NIS. We differentiated the data analysis between ballast-weighted ships and cargo laden ships according to nine ship categories: Tankers, LNG (Liquid Natural Gas) Ships, Bulk Carriers, General Cargo, Container Ships, Ro/Ro (Roll on/ off) ships, Car-Carriers, Passenger Ships, and Others. We used statistical tests to determine whether the August 2015 expansion influenced shipping trends and discuss our findings with respect to patterns in species introductions. Our findings show that although there has been an increase in tonnage being shipped through the Canal, this is a consequence of an increase in ship dimensions, while the actual number of ships for some categories has decreased. This pattern was particularly evident in the container ship category, which had the highest global growth compared to other ship categories. A few categories, such as bulk carriers and tankers, had more traffic in particular directions of passage. Only passenger ships and bulk carriers revealed significant seasonal transit trends, with higher transfers during spring and autumn for passenger ships and summer/autumn for bulk carriers. An increase in average ship size was evident for almost all categories. Larger ships imply a longer turnover time spent in ports and a larger available wetted surface area that is susceptible to fouling, thus potentially providing a larger fouling community with more time to propagate and settle in a novel habitat. Our findings emphasize the importance of identifying current shipping trends that may pose a threat to the Mediterranean Sea biodiversity in order to construct a follow-on policy to mitigate the transfer and delivery of NIS via the Suez Canal. Specifically, enforcement of antifouling regulations is highlighted as a significant contribution to the European Union Marine Strategy Framework Directive goals to achieve a good environmental status.

Ballast water management systems (BWMS) are shipboard devices designed to treat ballast water such that concentrations of living or viable organisms in discharged water are sufficiently low to meet state, national, or international limits. At land-based, purpose-built test facilities, BWMS undergo a rigorous verification process to confirm their efficacy. Currently, concentrations of living organisms in treated water are determined by manual microscope counts. We considered sources of uncertainty associated with these measurements and performed empirical estimates of variability in samples representative of the initial, uptake water (with correspondingly high concentrations of organisms) and in samples representative of treated water (with low concentrations of organisms, near the discharge limits for organisms ≥ 50 µm and organisms ≥ 10 and < 50 µm in minimum dimension). The sources of uncertainty included both systematic error—here, the loss of organisms during sampling—and random error—represented by variability in organisms counts among analysts and among replicate subsamples, as well as variability across measurements of sample volumes. Systematic error for organisms ≥ 50 µm was measured by the recovery rates of 150-µm diameter microbeads in field-scale trials. This error was substantial: recovery rates were 76 ± 11%; n = 18 replicate trials. The greatest source of random error was due to variation in counts of organisms among replicate subsamples, with average coefficients of variation (CV, %) ranging from 10% to 37% for organisms ≥ 50 µm. The variations among analysts’ counts of organisms and volumetric measurements, however, were negligible, approximately one order of magnitude smaller. Likewise, pipetting errors were unimportant.

Gastropods are amongst the most popular of the Mollusca in the pet trade, with globalisation being the main contributing factor facilitating their establishment globally. Although it is known that gastropods are kept as pets in South Africa, relatively little has been documented on the trade for this group. Physical pet stores selling gastropod species were surveyed seasonally in South Africa, aiming to determine 1) the types of species sold, including their trade popularity, trade volume, and the biogeographic realms they originated from, and 2) seasonal variations in gastropod species traded. Six gastropod species were recorded in the South African pet stores with three known invasives (Achatina fulica, A. immaculata, and Pomacea canaliculata). Of these species, the African giant snail A. fulica and the channelled golden apple snail P. canaliculata were the species with higher trade popularity throughout the year. The trade of the other species fluctuated with seasons among pet stores and provinces. Gastropod species sampled in this study originated from four biogeographic realms, with two species from the Afrotropical and Neotropical realms, and one each from the Indomalayan and the Palaearctic. The number of gastropod individuals observed in this study was relatively large; as a result, they may pose a potential risk of invasion should they be released or escape captivity. The pet trade industry at a national level needs to be regularly monitored and the policies on selling invasive non-native species should be implemented to avoid the introduction and establishment of potential invaders.

A pathways risk assessment is a part of an integrated assessment for the horizon scanning of non-indigenous species introductions. We examined past pathways, and their vectors, of aquatic NIS already present in Belarus in order to predict those species likely to spread to Belarus and arrive to Western Europe along the Central European invasion corridor. Twenty-four aquatic non-indigenous macroinvertebrates are known within Belarusian rivers, lakes and reservoirs, six of these have already spread westwards through Belarus. The modes of spread for these NIS were vessel transport, navigation corridors, and natural spread following an initial introduction.

The extremely invasive Old World Climbing Fern, Lygodium microphyllum, has invaded New World tropical and subtropical habitats. Lygodium microphyllum has indeterminate twining leaves that grow up on and shade out host shrubs and trees, their epiphytes, and the understory. This invasive plant threatens numerous native habitats in Florida USA and the Caribbean, including internationally valued conservation lands such as Everglades National Park. Fire, which can reduce or stimulate growth and/or reproduction in different plant species, is one intervention used to manage L. microphyllum, but the effects of burning on this species’ growth are unknown. We experimentally burned greenhouse-grown plants, then monitored their growth in response to burning for 18 months. We also clipped a subset of the greenhouse plants to determine whether fire effects were explained by aboveground biomass removal. In our experiment, fire either killed or reduced the regrowth of L. microphyllum plants. Burning killed 25% of the burned plants and slowed growth of the remaining burned plants for up to 18 months post-burn. Size had a significant effect on plant mortality: smaller burned plants had greater mortality than larger plants. Mechanically removing the aboveground biomass (leaves) by clipping did not kill any plants but reduced their growth as compared to controls in the first six months after treatment. Clipped plants, however, had substantially recovered after 12 months. Burned plants were more sensitive to drought than clipped or control plants. The results show that burning does more than remove biomass, compromising the root system and perhaps damaging the hydraulic support system, similar to the latent mortality effects of fire on forest trees. We discuss how fire could affect invasion by this species, incorporating fire effects on spore viability and dispersal, as well as on subsequent plant regrowth. These results show that fire is a useful management tool for L. microphyllum invasions that both kills plants and reduces plant regrowth for up to 18 months.

It has been demonstrated that Ipomoea batatas (L.) Lam (sweet potato) has greater soil nutrient absorption ability when grown in association with the invasive plant Mikania micrantha Kunth (mile-a-minute), but the competition interaction of the two plant species under different fertilization levels is not well characterized. The current study utilized a de Wit replacement series incorporating three ratios of I. batatas and M. micrantha densities and four different fertilizer levels in 16 m² plots. In mixed culture, the total shoot length, branch, leaf, and biomass of M. micrantha were significantly suppressed (P < 0.05) by I. batatas. With increasing fertilization, total shoot length, branch, leaf, and biomass of I. batatas and M. micrantha were significantly increased, but at a greater rate for I. batatas than for M. micrantha. Relative yield parameters demonstrated that intraspecific competition was less than interspecific competition and that I. batatas had a higher competitive ability than M. micrantha under different fertilization levels. Fertilization significantly impacted the photosynthetic rate (Pn) of these species in June and July, whereas density ratio had greater effect on Pn of both species in August and September. Growth rates of I. batatas were markedly higher than those of M. micrantha in July and August, but less than those of M. micrantha in June and September. The concentrations of soil organic matter, and available N, P, and K in M. micrantha infested soil were significantly greater (P < 0.05) than soils where I. batatas was grown in monoculture, and fertilization levels were reduced by the presence of I. batatas in mixed culture. With increased fertilization, soil nutrient absorption increased, at a greater rate for I. batatas than for M. micrantha. Our results demonstrated that I. batatas could gain greater competitive advantage from enriched fertilization levels than M. micrantha. If I. batatas is incorporated into cropping system rotations, optimal fertilizer levels could be designed using information from our study to produce high I. batatas yields in addition to the benefits of suppressing invasive plants like M. micrantha.

Alien invasive species are major drivers of ecological change worldwide, being especially detrimental in oceanic islands, where they constitute one of the greatest threats to the survival of native species. Ring-necked parakeets Psittacula krameri (Scopoli, 1769) are popular pets and individuals escaped from captivity have formed multiple self-sustainable populations outside their native range. For over ten years, free-ranging ring-necked parakeets have regularly been observed in Madeira Island (Portugal) and strong evidence suggests that they have breed multiple times in Funchal, the capital of the island. Herein, we assess the current status of Psittacula krameri in Madeira and discuss the possible ecological and economic impacts of established populations of this non-native parakeet. Given the initial stage of the incursion, we advocate for a “rapid response” intervention aimed at preventing the spread of this potential invader.

The UN Convention on Biological Diversity has declared invasive species a global threat and requested increased data sharing to prevent further impact. Existing worldwide and local databases mainly focus on distribution, abundance, identification, and impacts of invasive species, but very few record management activities. In the Niagara region of Ontario, Canada, no database focuses specifically on invasive species management. The goal of this study was to document current aquatic and riparian invasive species management activities in the Niagara region and develop a database that would become a tool to facilitate collaboration at the regional level. The objectives were to (1) inventory current invasive species detection and control activities in the Niagara region; (2) examine perceived efficacy of control techniques; and (3) develop a database integrated with a GIS mapping component. Seventy-one organizations involved in riparian/aquatic invasive species management in the Niagara region were contacted and 16 in-depth interviews were conducted. In 2017–2018, 35 separate control efforts were reported, involving 10 riparian invasive species and two aquatic invasive species, mostly concentrated along the Niagara River. Collaboration efforts were minimal, occurring for only six specific projects. Recommendations include develop a regional invasive species plan; increase control efforts along the Welland Canal and Lake Erie shoreline; adopt a wider variety of control techniques; and increase collaboration, information-sharing and resource-sharing among organizations. Overall, the newly developed database provides a baseline for the current state of aquatic and riparian invasive species management activities in the region. It can also help bridge the gap between invasive species science and decision-making by forming a tool to identify resource-sharing opportunities, management efficacy, priority areas, areas of improvement, and future resource needs. The database will enrich the global invasive species information network by providing Niagara-specific information. The database could also act as a model for tracking management activities of other invasive species and in other regions of North America.

Risk-based prioritization for early detection monitoring is of utmost importance to prevent and mitigate invasive species impacts and is especially needed for large ecosystems where management resources are not sufficient to survey all locations susceptible to invasion. In this paper we describe a spatially-explicit and quantitative approach for identifying the highest risk sites for aquatic invasive species (AIS) introduction into the United States’ waters of the Laurentian Great Lakes, a vast inland sea with a surface area of 246,049 square km and a shoreline length of 16,431 km. We compiled data from geospatial metrics available across all of the US waters of the Great Lakes as surrogates for propagule pressure from the dominant AIS pathways. Surrogates were weighted based on the observed or expected contribution of each pathway to past (historic) and predicted future invasions. Weighted surrogate data were combined to generate “invasion risk” scores for plants, invertebrates, fish, and all taxa combined at 3,487 management units (9 km × 9 km). The number of sites with invasion risk scores > 0 is: for plants (490), for invertebrates (220), for fish (436), and for all taxa (403). The rank order of sites with the highest risk scores varies by taxa, but in general the top thirty highest risk sites are the same across all groups. For all taxonomic groups, we show that the “top 30” sites account for at least 50% of predicted propagule pressure to the basin from all pathways. Many of the highest risk sites are located in western Lake Erie, southern Lake Michigan, and the St. Clair-Detroit River System. This framework provides a starting point for objective surveillance planning and implementation that can be adaptively improved.