A horizon scan exercise for aquatic invasive alien species in Iberian inland waters

Trouble on the horizon: anticipating biological invasions through futures thinking

Anticipating future biosecurity threats to prevent their occurrence is the most cost-effective strategy to manage invasive alien species. Yet, biological invasions are complex, highly uncertain processes. High uncertainty drives decision-making away from strategic preventative measures and towards operational outcomes aimed at post-invasion management. The limited success of preventative measures in curbing biological invasions reflects this short-term mindset and decision-makers should instead apply strategic foresight to imagine futures where biosecurity threats are minimised. Here, four major futures thinking tools (environmental scanning, driver-mapping, horizon scanning, and scenario planning) that describe probable, possible, plausible and preferable futures are assessed in terms of their potential to support both research and policy addressing biological invasions. Environmental scanning involves surveying existing data sources to detect signals of emerging alien species through knowledge of changes in either the likelihood or consequences of biological invasions. Several approaches are widely used for biosecurity including automated scans of digital media, consensus-based expert scoring, and prediction markets. Automated systems can be poor at detecting weak signals because of the large volume of 'noise' they generate while expert scoring relies on prior knowledge and so fails to identify unknown unknowns which is also true of prediction markets that work well for quite specific known risks. Driver-mapping uses expert consensus to identify the political, economic, societal, technological, legislative, and environmental forces shaping the future and is a critical component of strategic foresight that has rarely been applied to biological invasions. Considerable potential exists to extend this approach to develop system maps to identify where biosecurity interventions may be most effective and to explore driver complexes to determine megatrends shaping the future of biological invasions. Horizon scanning is a systematic outlook of potential threats and future developments to detect weak signals of emerging issues that exist at the margins of current thinking. Applications have been strongly focused on emerging issues related to research and technological challenges relevant to biosecurity and invasion science. However, most of these emerging issues are already well known in current-day research. Because horizon scanning is based on expert consensus, it needs to embrace a diversity of cultural, gender, and disciplinary diversity more adequately to ensure participants think intuitively and outside of their own subject boundaries. Scenario planning constructs storylines that describe alternative ways the political, economic, social, technological, legislative, and environmental situation might develop in the future. Biological invasion scenario planning has favoured structured approaches such as standardised archetypes and uncertainty matrices, but scope exists to apply more intuitive thinking by using incasting, backcasting, or causal layered analysis. Futures thinking in biological invasions has not engaged with decision-makers or other stakeholders adequately and thus outcomes have been light on policy and management priorities. To date, strategic foresight addressing biological invasions has applied each approach in isolation. Yet, an integrated approach to futures thinking that involves a diverse set of stakeholders in exploring the probable, possible, plausible, and preferable futures relating to biological invasions is crucial to the delivery of strategic biosecurity foresight at both national and global scales.

Management Measures and Trends of Biological Invasions in Europe: A Survey-Based Assessment of Local Managers

Biological invasions are a major threat to biodiversity, ecosystem functioning and nature's contributions to people worldwide. However, the effectiveness of invasive alien species (IAS) management measures and the progress toward achieving biodiversity targets remain uncertain due to limited and nonuniform data availability. Management success is usually assessed at a local level and documented in technical reports, often written in languages other than English, which makes such data notoriously difficult to collect at large geographic scales. Here we present the first European assessment of how managers perceive trends in IAS and the effectiveness of management measures to mitigate biological invasions. We developed a structured questionnaire translated into 18 languages and disseminated it to local and regional managers of IAS in Europe. We received responses from 1928 participants from 41 European countries, including 24 European Union (EU) Member States. Our results reveal substantial efforts in IAS monitoring and control, with invasive plants being the primary focus. Yet, there is a general perception of an increase in the numbers, occupied areas, and impacts of IAS across environment and taxonomic groups, particularly plants, over time. This perceived increase is consistent across both EU and non-EU countries, with respondents from EU countries demonstrating more certainty in their responses. Our results also indicate a lack of data on alien vertebrates and invertebrates, reflecting a need for more targeted monitoring and knowledge sharing between managers and policymakers and between countries. Overall, our study suggests that Europe's current strategies are insufficient to substantially reduce IAS by 2030 and hence to meet the Kunming-Montreal Global Biodiversity Framework target.

Framing challenges and polarized issues in invasion science: toward an interdisciplinary agenda

In a hyperconnected world, framing and managing biological invasions poses complex and contentious challenges, affecting socioeconomic and environmental sectors. This complexity distinguishes the field and fuels polarized debates. In the present article, we synthesize four contentious issues in invasion science that are rarely addressed together: vocabulary usage, the potential benefits of nonnative species, perceptions shifting because of global change, and rewilding practices and biological invasions. Researchers have predominantly focused on single issues; few have addressed multiple components of the debate within or across disciplinary boundaries. Ignoring the interconnected nature of these issues risks overlooking crucial cross-links. We advocate for interdisciplinary approaches that better integrate social and natural sciences. Although they are challenging, interdisciplinary collaborations offer hope to overcome polarization issues in invasion science. These may bridge disagreements, facilitate knowledge exchange, and reshape invasion science narratives. Finally, we present a contemporary agenda to advance future research, management, and constructive dialogue.

Predicting the risk of invasion by broadleaf watermilfoil (Myriophyllum heterophyllum) in mainland Portugal

Broadleaf water milfoil (Myriophyllum heterophyllum) is an emerging invasive alien plant in Europe, and thus a priority for European Union (EU)-level surveillance, monitoring, and eradication. This species is native to North America and threatens aquatic ecosystems by creating dense stands that can fill an entire water body, leading to high economic costs and the loss of native biodiversity. Although its presence in Portugal is not reported, the species has already been established in several European countries, including neighboring Spain. In this study, we assessed the risk of invasion by this species in mainland Portugal by jointly considering environmentally suitable areas and the risk of human-mediated introduction. Environmental suitability was estimated using MaxEnt, which relates the known species distribution to climate, topography, and soil variables. The model achieved a mean area under the curve value of 0.96 ± 0.008 and identified the mean temperature of the warmest quarter as the most relevant variable for explaining the species distribution (67.2 %). Predictions from the model indicated that the peaks of suitability values were distributed mainly in temperate climate regions along central and northern coastal areas in Portugal. The risk of introduction was estimated by mapping and calculating the spatial density of the aquarium stores. Jointly considering environmental suitability and risk of introduction, we observed that hotspots at risk of invasion are concentrated on the Portuguese central and northern coasts and in the two main metropolitan areas, Lisbon and Porto. Several risk hotspots fall within protected areas and sites designated under the EU Habitats Directive, comprising water bodies of high significance for maintaining local vegetation and fauna. Therefore, it is necessary to take measures to reduce the risk of invasion by this species, namely, surveillance and monitoring efforts confirming its absence in the national territory and preventing its future arrival.

Exploring the uptake of advanced digital technologies in environmental assessment practice - Experiences from Austria and Germany

Environmental assessment (EA) evaluates the environmental impacts of proposed projects, plans or policies to inform decision making. While several studies have highlighted the potential and opportunities of digitalisation for EA, few have explored practitioners' perceptions using a mixed methods approach in order to discover concerns and risks identified by EA of novel technological approaches. In addition, this initial exploratory study examines the perception of benefits and contributions to quality and effectiveness of advanced digital approaches, such as the introduction of artificial intelligence, in EA practice. The research process was based on focus group discussions and exploratory interviews with EA consultants, environmental authorities, researchers, environmental associations and NGOs. Relevant technologies were identified from the existing scientific literature and their applicability, benefits and use were discussed in context of real-world experience made by the practitioner. It became evident that the majority of practitioners in the field of EA in Austria and Germany are not familiar with advanced digital approaches and tools. While other planning disciplines are exploiting the potential of advanced digital tools, EA practitioners still share concerns about data quality, security, legal uncertainties, but also skills and know-how. The study identifies a gap and a need for training and confidence building. It aims to contribute to the promotion of inter- & transdisciplinary exchange involving the wider EA community.

Procambarus virginalis Lyko, 2017: A new threat to Iberian inland waters

An eco-monitoring programme to assess faunal biodiversity in the main rivers of the northern Iberian Peninsula (Spain) reveals the first occurrence of the marbled crayfish Procambarus virginalis (Decapoda: Cambaridae) in Iberian inland waters. Iberian specimens have been identified by combining morphological and genetic traits. We discuss the most plausible pathways and introduction vectors, its potential invasiveness and subsequent impacts on host localities. Our preliminary results raise concern about the potential threat of P. virginalis to native fauna and ecosystem dynamics, as P. virginalis was found in an area of great cultural and ecological importance with relevant populations of endangered species. Due to the invasive history of the marbled crayfish, eradication of these individuals is urgent. This study confirms the importance of early warning systems for exotic species, keeping the population, forest guards and field technicians informed about potential invasive species to execute a rapid and effective response.

Identification of potential invasive alien species in Spain through horizon scanning

Invasive alien species have widespread impacts on native biodiversity and ecosystem services. Since the number of introductions worldwide is continuously rising, it is essential to prevent the entry, establishment and spread of new alien species through a systematic examination of future potential threats. Applying a three-step horizon scanning consensus method, we evaluated non-established alien species that could potentially arrive, establish and cause major ecological impact in Spain within the next 10 years. Overall, we identified 47 species with a very high risk (e.g. Oreochromis niloticus, Popillia japonica, Hemidactylus frenatus, Crassula helmsii or Halophila stipulacea), 61 with high risk, 93 with moderate risk, and 732 species with low risk. Many of the species categorized as very high or high risk to Spanish biodiversity are either already present in Europe and neighbouring countries or have a long invasive history elsewhere. This study provides an updated list of potential invasive alien species useful for prioritizing efforts and resources against their introduction. Compared to previous horizon scanning exercises in Spain, the current study screens potential invaders from a wider range of terrestrial, freshwater, and marine organisms, and can serve as a basis for more comprehensive risk analyses to improve management and increase the efficiency of the early warning and rapid response framework for invasive alien species. We also stress the usefulness of measuring agreement and consistency as two different properties of the reliability of expert scores, in order to more easily elaborate consensus ranked lists of potential invasive alien species.

The challenge of managing threatened invasive species at a continental scale

The European Union's (EU) environmental legislation establishes common measures to prevent the entry and spread of invasive non-native species and to minimize their impacts. However, species that are native to at least one member state but non-native and potentially invasive in others (NPIS) are in limbo because they are neither legally regulated at the EU level nor in most member states. We used the Communication and Information Resource Centre for Administrations, Businesses and Citizens (CIRCABC) raw data on NPIS (317 taxa) to analyze their distribution across the EU and identify which biogeographical regions are the main sources of invasions. We additionally evaluated the conservation challenge posed by NPIS that are threatened within their native ranges. We performed a pairwise analysis summarizing the number of species that are native to a given member state but non-native to another and vice versa. Although distribution patterns of NPIS varied across taxa groups, overall, southern and central EU countries were both donors and recipients of NPIS. Eastern countries were mainly a source, and western and northern countries mostly received NPIS. Around 27% of NPIS were threatened in some of their EU native ranges, which is a challenge for conservation and management because some of them have serious negative effects on European biodiversity, but hitherto remain outside the scope of the EU regulation of invasive non-native species. This highlights an unresolved paradox because efforts to manage species as invasive conflict with efforts to protect them as threatened within the same territory.

Identifying and Managing Areas under Threat in the Iberian Peninsula: An Invasion Risk Atlas for Non-Native Aquatic Plant Species as a Potential Tool

Predicting the likelihood that non-native species will be introduced into new areas remains one of conservation's greatest challenges and, consequently, it is necessary to adopt adequate management measures to mitigate the effects of future biological invasions. At present, not much information is available on the areas in which non-native aquatic plant species could establish themselves in the Iberian Peninsula. Species distribution models were used to predict the potential invasion risk of (1) non-native aquatic plant species already established in the peninsula (32 species) and (2) those with the potential to invade the peninsula (40 species). The results revealed that the Iberian Peninsula contains a number of areas capable of hosting non-native aquatic plant species. Areas under anthropogenic pressure are at the greatest risk of invasion, and the variable most related to invasion risk is temperature. The results of this work were used to create the Invasion Risk Atlas for Alien Aquatic Plants in the Iberian Peninsula, a novel online resource that provides information about the potential distribution of non-native aquatic plant species. The atlas and this article are intended to serve as reference tools for the development of public policies, management regimes, and control strategies aimed at the prevention, mitigation, and eradication of non-native aquatic plant species.

Non-indigenous aquatic fauna in transitional waters from the Spanish Mediterranean coast: A comprehensive assessment

Understanding drivers of spatial variation in non-indigenous species (NIS) is a key goal in invasion biology, but comprehensive assessments providing high-resolution data are extremely scarce. Anthropogenic modifications to transitional waters facilitate the invasion of NIS where they cause both ecological and economic important damage. By screening validated data sources, we conducted a comprehensive assessment of non-indigenous aquatic fauna in Spanish Mediterranean transitional waters (30 sites), as well as assessed introduction pathways, native regions, NIS assemblage patterns and temporal introduction rate. One hundred and twenty-nine NIS were inventoried, with 72 % established and more than half listed before 1980. Two intentional (release, escape) and two unintentional (contaminant, stowaway) introduction pathways were dominant. Recorded NIS originated mostly from North America and Asia. A clear nested pattern in NIS assemblages was observed across sites, suggesting secondary spread from the most invaded waters placed in the northern regions. Our updated inventory should be pivotal for designing prevention protocols and informing specific management plans on non-indigenous fauna in transitional waters.