In the last ten years Araipama gigas, commonly known as pirarucu, expanded its distribution upstream into the Madeira River rapids where it is not a native species. The invasion was favored by escapes from Peruvian fish farms upstream in the Madeira River Basin, where they have been raising pirarucu since the 1970s. Although the Madeira River rapids had formerly represented a geographical barrier to this invasion by limiting floodplain habitats, the construction of the Santo Antônio and Jirau dams in 2011 flooded the two most important falls, replacing the rapids stretch with a lentic or semi-lentic habitat favoring the invasion of A. gigas. Since construction of the dams, fisheries reports have been marked by the decrease of traditional commercial species, coupled with the presence of invasive populations of A. gigas. This example highlights a major emergent threat to artisanal fishing in the Amazonian freshwater system: government policies favoring dam construction and the consequent spread of native fish species used in aquaculture to new regions upstream of waterfalls where they are not native.

Invasive and medically important arthropods continue to spread and establish worldwide whilst adversely impacting ecosystems and public health. As the eradication and population suppression of these invaders and pests can be highly problematic and frequently unsuccessful, prevention of their further spread and establishment is imperative. Currently, however, there remains a lack of efficacious and cost-effective spread prevention techniques; particularly for species with complex life histories that span both aquatic and terrestrial habitats, such as mosquitoes. Here, we examine the use of steam exposure and disinfectant (Virkon® Aquatic) treatments to cause mortality of juvenile life stages of two invasive disease vector mosquitoes, Aedes albopictus and Culex quinquefasciatus. Steam treatments induced total mortality of A. albopictus and C. quinquefasciatus egg stages, following thirty second and five second exposures, respectively. Hatchability of A. albopictus eggs was substantially reduced following ten seconds of steam exposure. Total A. albopictus larval mortality was caused by steam exposures of one second or longer. Conversely, the aquatic disinfectant failed to impede hatchability of A. albopictus or C. quinquefasciatus egg stages. However, disinfection with Virkon® Aquatic caused up to total mortality of mosquito larvae at exposure durations exceeding one minute at 4% concentrations, and five minutes at 1% concentrations. Our results suggest that steam treatments could be implemented as a biosecurity technique to prevent spread and establishment of invasive mosquitoes. Whilst the efficacy of chemical disinfections to cause mortality was not apparent towards mosquito eggs, applications could achieve significant mortality towards larvae in aquatic environments.

Aquatic invasive alien species (IAS) negatively impact freshwater ecosystems worldwide. As suppression and eradication of established invader populations are often complex, costly and resource-intensive, the prevention of further invader spread is considered a key aspect of proactive management measures. Although broad-spectrum aquatic disinfectants have been suggested as a suitable decontamination mechanism to enhance invader spread-prevention strategies, inconsistencies concerning their effectiveness are reported within the literature. Here, we examine the use of two aquatic disinfectants, which were developed to kill damaging microbes, to induce substantial degradation of the apical fragmentary propagules of five invasive macrophytes: Crassula helmsii (Kirk) Cockayne; Egeria densa Planchon; Elodea canadensis Michx; Hydrocotyle ranunculoides Linnaeus; Lagarosiphon major (Ridley) Moss. Apical fragments were exposed to 0% (0 g L^-1), 2% (20 g L^-1) or 4% (40 g L^-1) solutions of Virkon® Aquatic and Virasure® Aquatic, for submergence treatments of five, fifteen, thirty or sixty minutes. After 28 days, degradation of treated fragments was significantly greater than that of control groups, particularly for 4% solutions and longer exposure times. Despite this, sustained viability in relation to shoot and/or root regrowth was exhibited by almost all plant species. However, new shoot growth rates were significantly reduced following exposure to all treatments. At matched concentrations, there was no significant difference between the two disinfectants. Overall, it appears that the examined aquatic disinfectants will not curtail the spread of these invasive macrophytes. Yet, longer submergence times, multiple applications and synergistic effects of different biosecurity treatments may enhance preventative measures against further spread and this requires investigation.

The invasive red swamp crayfish poses a significant threat to physical habitat quality and biodiversity of aquatic communities in western U.S. streams. With no natural predators or competitors, crayfish can consume adult, juvenile, and egg forms of native fish, amphibians, and benthic macroinvertebrates. In addition, crayfish can destroy physical structures and disrupt nutrient and sediment dynamics by burrowing into banks and increasing turbidity. Mountain Restoration Trust has managed crayfish populations in the Santa Monica Mountains for almost a decade, yet evaluation of trap type effectiveness has remained a constant source of uncertainty in overall management efforts. In this two-week field experiment, we compared 12 trap designs including refuge traps, baited pyramid traps, and baited minnow traps with different colors and opening sizes to determine which traps caught the most crayfish and least bycatch. There were significant differences observed across the traps tested in the number of crayfish, chub, and tadpoles caught. The most effective trap for catching crayfish were both mesh traps, the Promar mesh 503 trap (mean daily crayfish catch = 1.9, SE = 0.24) and the Promar mesh 501 trap (mean daily crayfish catch = 1.2, SE = 0.26). The least effective traps, that caught more bycatch than crayfish, were the painted-black Gee Minnow trap (mean daily chub bycatch = 3.3, SE = 0.98) and the customized Pyramid trap with 5.1 cm openings (mean daily chub bycatch = 3.2, SE = 1.30). When managing for crayfish in southern California, arid-environment streams, we recommend deploying a combination of the Promar mesh 503 trap, the Promar mesh 501 trap, and/or the black Promar (2.5 cm). The combination of these traps can maximize crayfish catch efficiency and limit negative impacts on native fish and tadpole bycatch.

Eurasian zebra and quagga mussels were likely introduced to the Laurentian Great Lakes via ballast water release in the 1980s, and their range has since expanded across the US, including some of their southernmost occurrences in Texas. Their spread into the state has resulted in a need to revise previous delimitations of suitable dreissenid habitat. We therefore assessed invasion risk in Texas by 1) predicting distribution of suitable habitat of zebra and quagga mussels using Maxent species distribution models based upon global occurrence and climate data; and 2) refining lake-specific predictions via collection and analysis of physicochemical data. Maxent models predicted a lack of suitable habitat for quagga mussels within Texas. However, models did predict the presence of suitable zebra mussel habitat, with hotspots of suitable habitat occurring along the Red and Sabine Rivers of north and east Texas, as well as patches of suitable habitat in central Texas between the Colorado and Brazos Rivers and extending inland along the Gulf Coast. Although predicted suitable habitat extended further west than in previous models, most of the Texas panhandle, west Texas extending toward El Paso, and the Rio Grande valley were predicted to provide poor zebra mussel habitat suitability. Collection of physicochemical data (i.e., dissolved oxygen, pH, specific conductance, and temperature on-site as well as laboratory analysis for Ca, N, and P) from zebra mussel-invaded lakes and a subset of uninvaded but high-risk lakes of North and Central Texas, did not refine model predictions because there was no apparent distinction between invaded and uninvaded lakes. Overall, we demonstrated that while quagga mussels do not appear to represent an invasive threat in Texas, abundant suitable habitat for continuing zebra mussel invasion exists within the state. The threat of continued expansion of this poster-child for negative invasive species impacts warrants further prevention efforts, management, and research.

Biological invasion pathways are strongly influenced by human behavior. This research aimed to build new understanding about public perceptions and expectations for possible management responses that might be used after detection of Asian carp in the Laurentian Great Lakes. Although the species are as yet unestablished, our research worked to inform communication that could be publicly responsive in the event of an invasion. Our objectives were to: 1) determine public risk perceptions associated with Asian carp; 2) determine public risk perceptions associated with different types of management responses to an Asian carp invasion; and 3) identify types of risk‐related information and communication that would influence community support for different types of eradication or control approaches. Objectives were achieved by using a two-phase approach. Phase one utilized an online, voluntary, self-administered survey with 2788 responses received from a convenience sample of Laurentian Great Lakes Basin residents. Phase two included three “Thinkshops” of fishing and boating stakeholders in southern Michigan. Across all hypothetical Asian carp invasion scenarios, the application of rotenone to a large area was the most frequently selected management response. When impacts from Asian carp and their management were discussed, study participants supported framing risks in terms of environment and economy. Insights herein provide new evidence that can help narrow the gap between how invasion risks are perceived and responded to by natural resource managers to reduce social conflicts over, and potentially address, invasive species threats more rapidly.

Potamopyrgus antipodarum is one of the most widespread invasive species worldwide and its expansion is ongoing. Although the snail has already been documented as surviving the digestive tract of various fish, there is insufficient data on potential riverine fish predators of P. antipodarum and of the ability of the snail to survive digestion by these fish. Lotic ecosystems are unfavourable for the upstream spread of this species by active movement and thus it is suspected that benthivorous riverine fish facilitate such upstream dispersion. In general, the results of this study indicated that P. antipodarum is not a preferable food object for the studied riverine fish. The study did indicate, however, that the invasive snail is capable of surviving the digestive tract of all the studied fish. As accidental consumption of abundant P. antipodarum with other food objects has already been documented, this study suggests that riverine fish can act as potential secondary dispersion vectors, facilitating the upstream dispersion of the snail.

Invasive rats are known to threaten natural resources and human health and safety. Island-wide rat eradication attempts have been increasing in number and scale during the past several decades, as has the frequency of eradication success. The most common method to remove all rats from an island is to broadcast anticoagulant rodenticide bait into every rat’s home range on the island. Broadcast of toxicants can put humans and other nontarget species in marine and terrestrial environments at risk of exposure. The persistence of anticoagulant residues is somewhat unknown, particularly in marine environments. Three years after ~ 18,000 kg of 25 mg/kg brodifacoum bait was broadcast across Wake Atoll to eliminate rats, we collected whole-body fish samples from six near-shore sites and one intermittently land-locked pond to test for brodifacoum residues. Of the 69 samples tested using high-performance liquid chromatography with fluorescence detection, 20 were suspected of brodifacoum contamination and therefore subject to more selective liquid chromatography-mass spectrometry analysis. Of those 20 fish, brodifacoum was detected in two individuals of blacktail snapper (Lutjanus fulvus), although at levels too low to be accurately quantified. Both fish containing detectable brodifacoum residues were caught within an intermittently land-locked pond in an area of the island that received heavy brodifacoum baiting, and not truly in the “marine environment”. Brodifacoum was not detected in any of the samples collected within the lagoon of the atoll or within near-shore waters outside the lagoon. These results demonstrate that under some circumstances very low levels of brodifacoum can occur in a low proportion of fish tissues for as long as three years after the application of the rodenticide to an environment. Such information is valuable in assessing the relative environmental risks associated with rodenticide use in rodent eradications for protection of threatened species and restoration of island ecosystems. The overall result is one of declining incidence and magnitude of residue concentrations over time and within limited environmental circumstances.

Invasive species are threatening biodiversity and ecosystem stability globally. The introduction of the California kingsnake (Lampropeltis californiae) on Gran Canaria, Canary Islands, Spain represents an emerging invasion that is already threatening endemic island species. Dead neonatal mice treated with 80-mg acetaminophen tablets are approved as a registered pesticide for control of invasive brown treesnakes (Boiga irregularis) in Guam and could potentially be used as an oral toxicant to control invasive California kingsnake populations. We sought to evaluate oral toxicity of acetaminophen and to determine the dosage necessary for lethal control of invasive California kingsnake populations. Dead mice inserted with a known acetaminophen dose (0 mg, 40 mg, 60 mg, and 80 mg) were fed to California kingsnakes from Gran Canaria. Each dose was tested in 20 male and 20 female snakes representing the size range found in Gran Canaria. After snakes ate their dead mouse, they were monitored for mortality, regurgitation, and time of death and regurgitation. Treatments of 60 mg and 80 mg had 100% mortality, while 40 mg had 87.5% mortality. No control snakes died. Time to death occurred on average 38.6 hours after consuming the dead mouse. The top two time to death models accounted for 97% of model weights and included variables dosage (mg/kg), sex, and dosage * sex or those terms plus body condition index. Out of the 116 snakes that died, 97 regurgitated the mouse that contained the acetaminophen capsule, and time to regurgitation was highly correlated with time to death. Acetaminophen is a highly effective oral toxicant for California kingsnakes. Dead mouse baits treated with acetaminophen have potential as a control method on Gran Canaria but should not solely be expected to protect native species or eradicate California kingsnakes on Gran Canaria. Future efforts should focus on preventing California kingsnakes from invading other Canary Islands.

Documenting the distribution and composition of non-native species populations can be challenging, especially when species cross jurisdictional boundaries that require interagency coordination. Herein I report the development of three tools that have been used in Florida over the past seven years to assist with tracking of non-native fishes: 1) an overarching organization to increase coordination and communication amongst stakeholders (Florida Non-Native Fish Action Alliance); 2) regularly-scheduled expert bioblitzes (Fish Slams); and 3) symposia (Fish Chats). Ten Fish Slams were held since 2012, which have included nearly 100 individuals from 20 organizations. Participants have sampled nearly 200 unique sites, capturing 36 non-native fish taxa. These activities have generated over 600 records for the U.S. Geological Survey’s Nonindigenous Aquatic Species database. Many specimens collected during Fish Slams are deposited into natural history museums or used by researchers. Informal interactions amongst colleagues working together in the field, at check-in meetings at the end of the day, and during more structured Fish Chat symposia allow members of various organizations to become acquainted, build trust, and share information and technology, which may then lead to professional collaborations. While this program is focused on non-native fish species in south Florida, I also discuss how the expert bioblitz may be adapted to suit other taxonomic groups and a variety of conservation needs.