Consensus and controversy in the discipline of invasion science

Approaches, values and perceptions in invasion science are highly dynamic, and like in other disciplines, views among different people can be somewhat divergent. This has led to debate in the field specifically surrounding the core themes relating to values, management, impacts, and terminology. Considering these debates, we surveyed the views of 698 scientists and practitioners to assess levels of polarization (opposing views) on core and contentious invasion science topics. Our results indicate that although there are generally high levels of consensus in the field, there are still some areas of polarization. Relating to values, there was high polarization regarding claims of invasive species denialism, if invasive species contribute to biodiversity, and, how biodiversity reporting should be conducted. Linking to management there were polarized views on banning the commercial use of beneficial invasive species, the extent to which stakeholders’ perceptions should influence management, if invasive species utilization alone is an appropriate control strategy, and, whether the eradication of invasive plants is possible. For impacts, there was high polarization concerning whether invasive species drive, or are a side effect of degradation, and, if invasive species benefits are understated. For terminology, polarized views related to defining invasive species based only on spread, if labelling species as invasive in their native ranges, and, if language used is too xenophobic. Factor and regression analysis revealed that views were particularly divergent between people working on different invasive taxa (plants and mammals) and in different disciplines (especially between biologists and social scientists), between academics and practitioners, and between world regions (especially between Africa and the Global North). Unlike in other studies, age and gender had a limited influence on response patterns. We highlight that better integration globally and between disciplines, taxa and sectors (e.g., academic vs. practitioners), could help build broader understanding and consensus in the field

Clarification and guidance on the use of the Socio-Economic Impact Classification for Alien Taxa (SEICAT) framework

Understanding the ways in which alien taxa threaten human well-being, beyond purely monetary costs, can be difficult as impacts differ vastly across social, cultural, and economic contexts. Failure to capture impacts outside of monetary costs means that impacts are unfairly weighted towards those that can be easily monetised, which is unlikely to be a realistic measure of how alien species truly affect human well-being. To address this issue, the Socio-Economic Impact Classification for Alien Taxa (SEICAT) was developed with the intention to facilitate standardised classifications and comparisons of the impacts of alien taxa on human well-being and livelihood. The framework measures impacts by assessing to what extent alien taxa have altered human activities, so has application across a broad range of reported impacts associated with different constituents of human well-being. Although in their original paper, Bacher et al. (2018) provided an overview of the SEICAT framework, comprehensive guidelines that enable assessors to overcome potential ambiguities were, until now, unavailable. This may be preventing the broad application of the framework due to reduced usability. Here, we provide clarification and guidance for the application of SEICAT to facilitate standardised, consistent assessments. In particular, we address uncertainties stemming from unclear definitions of impacted communities and activities, as well as the spatial and temporal scales of relevance. We clarify these key issues and give explicit recommendations, whilst encouraging the collection of additional contextual information to be recorded for each assessed impact report, to generate more practical information for end-users of SEICAT data. Further, we recommend adopting an alternative terminology for the impact categories to reduce the potential misuse of the current descriptors. The intended outcome of this work is to aid the broad application of the SEICAT framework in a consistent and transparent manner

The EICAT+ framework enables classification of positive impacts of alien taxa on native biodiversity

Species introduced through human-related activities beyond their native range, termed alien species, have various impacts worldwide. The IUCN Environmental Impact Classification for Alien Taxa (EICAT) is a global standard to assess negative impacts of alien species on native biodiversity. Alien species can also positively affect biodiversity (for instance, through food and habitat provisioning or dispersal facilitation) but there is currently no standardized and evidence-based system to classify positive impacts. We fill this gap by proposing EICAT+, which uses 5 semiquantitative scenarios to categorize the magnitude of positive impacts, and describes underlying mechanisms. EICAT+ can be applied to all alien taxa at different spatial and organizational scales. The application of EICAT+ expands our understanding of the consequences of biological invasions and can inform conservation decisions

The EICAT+ framework enables classification of positive impacts of alien taxa on native biodiversity

Species introduced through human-related activities beyond their native range, termed alien species, have various impacts worldwide. The IUCN Environmental Impact Classification for Alien Taxa (EICAT) is a global standard to assess negative impacts of alien species on native biodiversity. Alien species can also positively affect biodiversity (for instance, through food and habitat provisioning or dispersal facilitation) but there is currently no standardized and evidence-based system to classify positive impacts. We fill this gap by proposing EICAT+, which uses 5 semiquantitative scenarios to categorize the magnitude of positive impacts, and describes underlying mechanisms. EICAT+ can be applied to all alien taxa at different spatial and organizational scales. The application of EICAT+ expands our understanding of the consequences of biological invasions and can inform conservation decisions.Agencia Estatal de Investigación PCI2018-092939, PCI2018-092986Swiss National Science Foundation 31003A_179491, 31BD30_184114Austrian Fonds zur Förderung der Wissenschaftlichen Forschung 4011-B32German Bundesministerium für Bildung und Forschung 16LC1803A, 01LC1807CFrench National Research Agency ANR-18-EBI4-0001-06US National Science Foundation ICER-1852060National Research Foundation of South Africa 89967Australian Research Council DP200101680UK Natural Environment Research Council NE/V007548/1Hellenic Foundation for Research and Innovation (H.F.R.I.) HFRIFM17-159

Identifying, reducing, and communicating uncertainty in community science:A focus on alien species

Community science (also often referred to as citizen science) provides a unique opportunity to address questions beyond the scope of other research methods whilst simultaneously engaging communities in the scientific process. This leads to broad educational benefits, empowers people, and can increase public awareness of societally relevant issues such as the biodiversity crisis. As such, community science has become a favourable framework for researching alien species where data on the presence, absence, abundance, phenology, and impact of species is important in informing management decisions. However, uncertainties arising at different stages can limit the interpretation of data and lead to projects failing to achieve their intended outcomes. Focusing on alien species centered community science projects, we identified key research questions and the relevant uncertainties that arise during the process of developing the study design, for example, when collecting the data and during the statistical analyses. Additionally, we assessed uncertainties from a linguistic perspective, and how the communication stages among project coordinators, participants and other stakeholders can alter the way in which information may be interpreted. We discuss existing methods for reducing uncertainty and suggest further solutions to improve data reliability. Further, we make suggestions to reduce the uncertainties that emerge at each project step and provide guidance and recommendations that can be readily applied in practice. Reducing uncertainties is essential and necessary to strengthen the scientific and community outcomes of community science, which is of particular importance to ensure the success of projects aimed at detecting novel alien species and monitoring their dynamics across space and time

The toxicity of the methylimidazolium ionic liquids, with a focus on M8OI and hepatic effects

Ionic liquids are a diverse range of charged chemicals with low volatility and often liquids at ambient temperatures. This characteristic has in part lead to them being considered environmentally-friendly replacements for existing volatile solvents. However, methylimidazolium ionic liquids are slow to break down in the environment and a recent study at Newcastle detected 1 octyl 3 methylimidazolium (M8OI) – an 8 carbon variant methylimidazolium ionic liquid - in soils in close proximity to a landfill site. The current M8OI toxicity database in cultured mammalian cells, in experimental animal studies and in model indicators of environmental impact are reviewed. Selected analytical data from the Newcastle study suggest the soils in close proximity to the landfill site, an urban soil lacking overt contamination, had variable levels of M8OI. The potential for M8OI - or a structurally related ionic liquid – to trigger primary biliary cholangitis (PBC), an autoimmune liver disease thought to be triggered by an unknown agent(s) in the environment, is reviewed

Using the IUCN Environmental Impact Classification for Alien Taxa to inform decision-making

The Environmental Impact Classification for Alien Taxa (EICAT) is an important tool for biological invasion policy and management and has been adopted as an International Union for Conservation of Nature (IUCN) standard to measure the severity of environmental impacts caused by organisms living outside their native ranges. EICAT has already been incorporated into some national and local decision-making procedures, making it a particularly relevant resource for addressing the impact of non-native species. Recently, some of the underlying conceptual principles of EICAT, particularly those related to the use of the precautionary approach, have been challenged. Although still relatively new, guidelines for the application and interpretation of EICAT will be periodically revisited by the IUCN community, based on scientific evidence, to improve the process. Some of the criticisms recently raised are based on subjectively selected assumptions that cannot be generalized and may harm global efforts to manage biological invasions. EICAT adopts a precautionary principle by considering a species’ impact history elsewhere because some taxa have traits that can make them inherently more harmful. Furthermore, non-native species are often important drivers of biodiversity loss even in the presence of other pressures. Ignoring the precautionary principle when tackling the impacts of non-native species has led to devastating consequences for human well-being, biodiversity, and ecosystems, as well as poor management outcomes, and thus to significant economic costs. EICAT is a relevant tool because it supports prioritization and management of non-native species and meeting and monitoring progress toward the Kunming–Montreal Global Biodiversity Framework (GBF) Target 6

The importance of assessing positive and beneficial impacts of alien species

Extensive literature is available on the diversity and magnitude of impacts that alien species cause on recipient systems. Alien species may decrease or increase attributes of ecosystems (e.g. total biomass or species diversity), thus causing negative and positive environmental impacts. Alien species may also negatively or positively impact attributes linked to local human communities (e.g. the number of people involved in a given activity). Ethical and societal values contribute to define these environmental and socio-economic impacts as deleterious or beneficial. Whilst most of the literature focuses on the deleterious effects of alien taxa, some recognise their beneficial impacts on ecosystems and human activities. Impact assessment frameworks show a similar tendency to evaluate mainly deleterious impacts: only relatively few, and not widely applied, frameworks incorporate the beneficial impacts of alien species. Here, we provide a summary of the frameworks assessing beneficial impacts and briefly discuss why they might have been less frequently cited and applied than frameworks assessing exclusively deleterious impacts. Then, we review arguments that invoke a greater consideration of positive and beneficial impacts caused by alien species across the invasion science literature. We collate and describe arguments from a set of 47 papers, grouping them in two categories (value- free and value-laden), which span from a theoretical, basic science perspective to an applied science perspective. We also provide example cases associated with each argument. We advocate that the development of transparent and evidence-based frameworks assessing positive and beneficial impacts might advance our scientific understanding of impact dynamics and better inform management and prioritisation decisions. We also advise that this development should be achieved by recognising the underlying ethical and societal values of the frameworks and their intrinsic limitations. The evaluation of positive and beneficial impacts through impact assessment frameworks should not be seen as an attempt to outweigh or to discount deleterious impacts of alien taxa but rather as an opportunity to provide additional information for scientists, managers and policymakers

Understanding uncertainty in the Impact Classification for Alien Taxa (ICAT) assessments

The Environmental Impact Classification for Alien Taxa (EICAT) and the Socio- Economic Impact Classification of Alien Taxa (SEICAT) have been proposed to provide unified methods for classifying alien species according to their magnitude of impacts. EICAT and SEICAT (herein “ICAT” when refered together) were designed to facilitate the comparison between taxa and invasion contexts by using a standardised, semi-quantitative scoring scheme. The ICAT scores are assigned after conducting a literature review to evaluate all impact observations against the protocols’ criteria. EICAT classifies impacts on the native biota of the recipient environments, whereas SEICAT classifies impacts on human activities. A key component of the process is to assign a level of confidence (high, medium or low) to account for uncertainty. Assessors assign confidence scores to each impact record depending on how confident they are that the assigned impact magnitude reflects the true situation. All possible sources of epistemic uncertainty are expected to be captured by one overall confidence score, neglecting linguistic uncertainties that assessors should be aware of. The current way of handling uncertainty is prone to subjectivity and therefore might lead to inconsistencies amongst assessors. This paper identifies the major sources of uncertainty for impacts classified under the ICAT frameworks, where they emerge in the assessment process and how they are likely to be contributing to biases and inconsistency in assessments. In addition, as the current procedures only capture uncertainty at the individual impact report, interspecific comparisons may be limited by various factors, including data availability. Therefore, ranking species, based on impact magnitude under the present systems, does not account for such uncertainty. We identify three types of biases occurring beyond the individual impact report level (and not captured by the confidence score): biases in the existing data, data collection and data assessment. These biases should be recognised when comparing alien species based on their impacts. Clarifying uncertainty concepts relevant to the ICAT frameworks will lead to more consistent impact assessments and more robust intra- and inter-specific comparisons of impact magnitudes