Search

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 broadspectrum 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. [ABSTRACT FROM AUTHOR]

Eradication and suppression strategies for established populations of invasive species require innovative but readily available techniques, which maximise efficacy whilst minimising environmental damage. The Asian clam, Corbicula fluminea (Müller, 1774), is a high impact freshwater invader that can dominate macroinvertebrate communities and physically alter benthic habitats. Globally, despite efforts to implement substantial population control measures, C. fluminea continues to invade, spread and persist within freshwater environments. Accordingly, improved eradication, population suppression and rapid reaction techniques are urgently required. As C. fluminea beds can often become exposed during low water conditions, the present study examines the efficacy of an open-flame heat torch, generating ~ 1000 °C, in killing exposed individuals. Direct and indirect applications of the open-flame torch were examined, for C. fluminea residing on top of or within the substrate, respectively. Experiments revealed that ≥ 3 seconds of direct exposure to the flame causes complete mortality of C. fluminea, while only low mortality rates of between 8-11% were achieved for mud-dwelling C. fluminea following 30 seconds of indirect exposure. However, a longer exposure time of 5 minutes can cause complete mortality of buried C. fluminea. Further, combined rake and burn treatments, where the substrate is disturbed between one minute flame applications, can completely kill all C. fluminea specimens residing within beds, following multiple applications. Overall, these results demonstrate that the application of open-flame heat torch treatments can be used for effective, rapid response and substantial population control of C. fluminea populations residing upon naturally and anthropogenically exposed river, lake and canal beds. Although promising, our laboratory results require up-scaling to field application, including examination of other substrate types, increased substrate depth, and greater bed densities of C. fluminea. [ABSTRACT FROM AUTHOR]

Aquatic invasive species (AIS) negatively impact freshwater ecosystems on a global scale. As management options for control and eradication of established AIS populations are often complex, costly and resource-intensive, spread-prevention protocols are considered essential. The Asian clam, Corbicula fluminea (Müller, 1774), is considered a high-impact successful invader that can adversely alter freshwater habitats, community dynamics and ecosystem function. Accordingly, we examine the efficacy of a range of biosecurity techniques, including recommended (aquatic disinfectants, bleach and salt solutions) and more novel (hot water and direct steam) approaches, to induce adult C. fluminea mortality. In separate experiments, C. fluminea were submerged at 12 °C for up to 80 minutes in: 1) 2% and 4% solutions of Virasure® Aquatic and Virkon® Aquatic; 2) warm (30 °C) 2% and 4% solutions of these disinfectants; and 3) 10% and 20% bleach solutions. Furthermore, specimens were exposed to: 4) 30% and 70% salt solutions (NaCl) for up to 72 hrs; 5) hot water (35, 40 and 45 °C) for up to 20 minutes; and 6), direct steam exposure for up to 10 minutes. Adult C. fluminea were found to be largely resistant to aquatic disinfectants, bleach and salt solutions, with ≤ 58% mortality achieved at the maximum exposure times. However, immersion in hot water (≥ 45 °C) and direct steam exposure for five minutes and 30 seconds, respectively, rapidly caused mortality. Accordingly, simple biosecurity protocols that cause thermal shock appear highly effective. We discuss the need for further examination of biosecurity protocols across all life stages of current, emerging and potential AIS, and provide guidance for improving biosecurity practices. [ABSTRACT FROM AUTHOR]

Outreach is an important element of scientific communication and a prescribed element of many projects, but few scientists have training in communications. This paper describes the outreach element of a project on invasive alien species. A communications plan was drawn up to streamline communications efforts, allowing us to take advantage of unanticipated opportunities to engage with the public, while still maintaining the desired focus, using minimal resources. Here, we use two simple metrics--"passive reach" and "interactions"--to measure the extent and the intensity of communications, and we also look at the advantages and limitations provided by different media. Broadcast media and social media have the capacity to reach a wide audience, but have a low percentage of interaction. Workshops and citizen science events tend to reach a much smaller audience, but generate greater levels of engagement. Understanding these dynamics is important in designing an effective communications plan, which uses the minimum number of resources to generate maximum impact. Building the credibility of the researcher or the project means that your research will reach a wider audience, and your message is more likely to have an impact. [ABSTRACT FROM AUTHOR]

Eradication and control measures for invasive aquatic organisms require innovative methods that maximise efficacy whilst minimising environmental damage. Such methods should also ideally utilise readily available materials and have a relatively straightforward field application. The Asian clam, Corbicula fluminea (Müller, 1774) is a high impact freshwater invader that can dominate macroinvertebrate communities and physically alter benthic habitats. Moreover, C. fluminea has shown a high degree of physiological and ecological plasticity, and has displayed a remarkable capacity for human-mediated passive dispersal. Globally, despite repeated efforts to mitigate spread and implement substantial population control measures, C. fluminea continues to invade and spread. Accordingly, effective population eradication and control measures are urgently required. Here, we examine the efficacy of commercially available dry ice (DI) pellets (i.e. solid CO2 pellets at -78 °C) to kill C. fluminea, when applied both directly (water absent) and indirectly (clams submerged). Experiment 1 revealed the ability of 9 mm DI pellets to induce substantial C. fluminea mortality, with a direct application of 300 g DI at 5 min exposure inducing 100% clam mortality. In experiments 2 and 3, DI pellets of 9 mm induced higher clam mortality than 3 mm pellets, DI slices and mixed DI pellet sizes (3 and 9 mm) at simulated clam densities of 1179 and 3930 individuals m-2, especially when clams were submerged. Experiments 4 and 5 showed that DI application was highly effective even with clams that were covered in gravel or mud, due to the freezing of their surrounding substrate. Accordingly, these results demonstrate that DI can potentially be used for effective, rapid response control and eradication of C. fluminea populations. Whilst promising, our laboratory results require scaling up to field application and examination of the effects of water current, substrate, increased water depth, and greater C. fluminea population densities. [ABSTRACT FROM AUTHOR]

Aquatic alien invasive species (AIS) are a substantial and increasing threat to biodiversity and ecosystem function worldwide. In particular, invasive aquatic macrophytes, such as the South African curly waterweed Lagarosiphon major ((Ridley) Moss 1928), induce major environmental change that often culminates in wide-ranging ecological and socio-economic impacts. Currently, there is a lack of effective biosecurity protocols to mitigate against such invader spread. Here, we examine the efficacy of a broad-spectrum aquatic disinfectant, Virasure® Aquatic, to induce mortality of L. major propagule stages. We assessed the efficacy of Virasure® Aquatic at contact times of 1, 2 and 5 minutes, using 1% (10g L-1) and 4% (40g L-1) concentrations. A necrosis scale was applied to visually assess tissue degradation. Necrosis increased with longer chemical contact times, with fragment degradation optimised at 2 minutes at 1% concentration and 1 minute at 4% concentration. Mode of application was also critical to treatment effectiveness, with spray treatments less effective than submersion treatments. We recommend the use of Virasure® Aquatic via submersion for a minimum period of 2 minutes at 1% concentration or higher. While spray applications should be applied when submersion is not feasible, such as with large water craft, increased spray times beyond those assessed here should be examined. However, results presented suggest that Virasure® Aquatic can effectively reduce the secondary spread of invasive L. major, and may thus form an integral part of biosecurity protocols. The use of broad-spectrum disinfectants and other readily available treatments, that were not purposefully developed for aquatic AIS control but nevertheless are emerging as effective in aquatic AIS management, is discussed and encouraged. [ABSTRACT FROM AUTHOR]