Freshwater ecosystems host high levels of biodiversity but are also highly vulnerable to biological invasions. Aquatic Invasive Alien Plant Species (aIAPS) can cause detrimental effects on freshwater ecosystems and their services to society, raising challenges to decision-makers regarding their correct management. Spatially and temporally explicit information on the occurrence of aIAPS in dynamic freshwater systems is essential to implement efficient regional and local action plans. The use of unmanned aerial vehicle imagery synchronized with free Sentinel-2 multispectral data allied with classifier fusion techniques may support more efficient monitoring actions for non-stationary aIAPS. Here, we explore the advantages of such a novel approach for mapping the invasive water-hyacinth (Eichhornia crassipes) in the Cávado River (northern Portugal). Invaded and non-invaded areas were used to explore the evolution of spectral attributes of Eichhornia crassipes through a time series (processed by a super-resolution algorithm) that covers March 2021 to February 2022 and to build an occurrence dataset (presence or absence). Analysis of the spectral behavior throughout the year allowed the detection of spectral regions with greater capacity to distinguish the target plant from the surrounding environment. Classifier fusion techniques were implemented in the biomod2 predictive modelling package and fed with selected spectral regions to firstly extract a spectral signature from the synchronized day and secondly to identify pixels with similar reflectance values over time. Predictions from statistical and machine-learning algorithms were ensembled to map invaded spaces across the whole study area during all seasons with classifications attaining high accuracy values (True Skill Statistic, TSS: 0.932; Area Under the Receiver Operating Curve, ROC: 0.992; Kappa: 0.826). Our results provide evidence of the potential of our approach to mapping plant invaders in dynamic freshwater systems over time, applicable in the assessment of the success of control actions as well as in the implementation of long-term strategic monitoring.

The overarching objective of OneSTOP is to pioneer an innovative and joined-up approach to biosecurity for terrestrial invasive alien species, strengthening the interconnections between animal, plant, human and environmental health. OneSTOP aims to harness current technologies and citizen science, while overcoming challenges posed by dispersed and fragmentary processes, policies, and knowledge, to deliver methods for identification, early detection and surveillance of invasive alien species. OneSTOP aims to achieve transformative results to minimise the introduction, establishment and spread of invasive alien species by integrating cutting-edge detection methods, underpinned by prioritisation and robust models, alongside stakeholder engagement to inform harmonised policies and facilitate knowledge exchange. The outcomes will be relevant for invasive alien species policy, noting the importance of enhancing collaboration and coordination across local, national, and regional scales, recognising that geographic boundaries do not confine the impact of these species. By adopting a holistic and interconnected approach, OneSTOP seeks to establish a strategy to achieve rapid and transformative progress in detecting, eradicating and controlling invasive alien animals and plants, ultimately contributing to a more secure and resilient environment. Throughout, OneSTOP is based upon the strategic actions recommended for integrated governance of biological invasions in the recently published IPBES Thematic assessment report on invasive alien species and their control (IPBES 2023).

Invasive alien species are a major driver of global environmental change. Escalating globalization processes such as international trade and long-distance transport have contributed to an increase in the ecological, economic, and sociocultural impacts of biological invasions. As a result, their management has become an increasingly relevant topic on environmental policy agendas. To better understand the role of policy in invasion science and to identify trends and gaps in policy-oriented research, a systematic literature review was conducted covering 2135 publications. The results highlight that international policy instruments are contributing to an increased interest in pursuing policy-oriented research. Specifically, key historical periods in policy development (e.g., the Convention on Biological Diversity’s COP10 in 2010) coincide with periods of active policy-focused research in invasion science. Research is, however, more applied to local scales (i.e., subnational, and national) and is more focused in places with high research capacity or where severe environmental or economic impacts are well documented.

Biological invasions are a major driver of global change with largely negative impacts on biodiversity, sustainability and human well-being. Understanding and predicting patterns and trends in future biological invasions requires a variety of model and scenario-based tools. Here, we present the outcome of the first comprehensive literature review synthesising the state of the art in model-based scenarios. Through a systematic review we considered the scope of studies in terms of spatial, temporal and taxonomic coverage, drivers of global change involved, model and scenario types covered, as well as facets of biological invasions including impacts, pathways and management. Additionally, we assessed the coverage of overarching themes relating biological invasions to human health and well-being, understanding the role of Indigenous and local knowledge for understanding biological invasion, and how biological invasions affect nature’s contributions to people. We found 1,268 studies (English-literature) using model-based scenarios, with 81% focussing on correlative modelling approaches developing forward-looking correlative scenarios. Target-seeking and policy-screening scenarios were less frequently developed in the literature (5 and 7% respectively). The main driver implemented in the model-based scenarios to shape future biological invasions is climate change (66%) with other important drivers like land-use change, socio-economy, policy or technology being substantially less covered. Cluster analysis revealed distinct groups of studies associated with different foci on: process-based models investigating species abundance changes, particularly in vertebrates over short-term futures until 2030, correlative models and quantitative exploratory scenarios focusing on projecting habitat suitability under climate change and other direct drivers, and expert-based and hybrid models that investigate changes in species richness and impacts under policy-screening and target-seeking scenarios. process-based models investigating species abundance changes, particularly in vertebrates over short-term futures until 2030, correlative models and quantitative exploratory scenarios focusing on projecting habitat suitability under climate change and other direct drivers, and expert-based and hybrid models that investigate changes in species richness and impacts under policy-screening and target-seeking scenarios. In summary, while we show that literature on model-based scenarios of biological invasions is advancing rapidly, there is a dominance of exploratory scenarios using correlative models to understand potential future changes in biological invasions by projecting large-scale patterns of alien species richness and distribution. The value of such approaches is widely recognized but our findings suggest that there could also be increased focus on regional and local scale scenarios. Impacts of invasive alien species are rarely included within studies. Furthermore, the voices of Indigenous People and local communities (IPLC) in particular, but also those of land managers and other relevant stakeholders are only included in a very small number of studies, indicating that future research might focus more strongly on co-development and collaboration with IPLC and other groups. To adequately inform future implementation of policy targets on invasive alien species, the share of target-seeking and policy-screening scenarios to explore the option space for different management interventions at local and global scales and across contexts (e.g., realms or habitats) needs to be increased. While recognizing the value and application of correlative models, we call for extending the breadth of these studies to routinely encompass more process-based and hybrid models approaches, as well as target-seeking and policy-screening scenarios. This way, model-based scenarios will contribute robustly to understanding the complex interplay amongst drivers of environmental change and specifically reveal plausible futures across social-ecological systems.

Invasive alien species are widely recognised as a major driver of biodiversity loss and ecosystem change. Their ecological impacts are expressed as measurable changes in ecosystem properties across levels of organisation, from genes to ecosystems, and vary in both direction and magnitude depending on social-ecological context. While this context-dependency is essential for understanding impacts within specific systems, it limits the extent to which findings can be synthesised, generalised and used in broader decision-making frameworks. As a result, large-scale ecosystem assessments have largely focused on quantifying and mapping invasion pressure, while a critical gap remains in capturing how this pressure translates into interpretable patterns of change in ecosystem state (i.e., quantifying the impact). Ecosystem condition provides a relevant framework to address this gap by characterising ecosystem integrity through the state of its biotic and abiotic components and their interactions, and can be assessed across dimensions of composition, structure, functioning, and supporting abiotic and landscape characteristics. Framing invasion impacts as patterns of change in ecosystem condition therefore enables the identification of comparable effects across ecological contexts. We present an evidence synthesis, combining a systematic review and meta-analysis, of empirical studies on the effects of invasion by alien species on forest ecosystem condition across Europe. Extracted metrics were classified into the six condition classes of the SEEA EEA Ecosystem Condition Typology (physical abiotic, chemical abiotic, composition, structure, functioning, and landscape) and analysed across invasive species groups, forest types, and biogeographic regions. We identify condition metrics that show consistent patterns of ecosystem response to invasion across contexts and evaluate their potential as impact indicators for large-scale assessments. We argue that this approach advances the integration of invasion impacts into large-scale ecosystem assessments and provides a basis for incorporating them into ecosystem service and natural capital accounting frameworks.

Public perceptions of invasive alien species are critical for the societal acceptance of management measures. However, there is limited comparative cross-country evidence regarding the combined influence of awareness, values, emotions, and communication framings on these perceptions. This study, conducted within the EU Horizon Europe project OneSTOP, presents findings from representative surveys of the general public (aged 18+) in Belgium, Finland, Portugal, Romania, and the United Kingdom (~500 respondents per country). Each country survey follows a shared structure but features two locally relevant invasive alien species—one plant and one animal—selected based on EU Union list status, public visibility, perceived charisma, and management controversy. To examine the influence of communication on attitudes, the survey included an embedded framing experiment: respondents were randomly assigned to one of three information treatments—a control providing general invasive alien species information, and two treatments presenting the same species framed through different justifications for management, such as biodiversity impact, environmental or cultural loss, economic cost, human health risks and social norm. Based on approximately 2,500 responses, we expect to provide insights into how awareness and knowledge influence public perceptions of invasive alien species across the five countries, and how these perceptions are further shaped by emotional responses associated with species charisma, perceived ecological and economic impacts, cultural significance, personal experience, and proximity. The findings are anticipated to show how these factors, together with socio-economic characteristics, influence public attitudes toward different management options, including support for eradication, control, or tolerance. The analysis aims to offer evidence on whether and how different framings shift attitudes toward management options, and which types of arguments most effectively increase support for action across countries and socio-demographic groups. The results will inform the development of targeted communication and citizen engagement strategies within and beyond the OneSTOP project.