Biological invasions continue to threaten the stability of ecosystems and societies that are dependent on their services. Whilst the ecological impacts of invasive alien species (IAS) have been widely reported in recent decades, there remains a paucity of information concerning their economic impacts. Europe has strong trade and transport links with the rest of the world, facilitating hundreds of IAS incursions, and largely centralised decision-making frameworks. The present study is the first comprehensive and detailed effort that quantifies the costs of IAS collectively across European countries and examines temporal trends in these data. In addition, the distributions of costs across countries, socioeconomic sectors and taxonomic groups are examined, as are socio-economic correlates of management and damage costs. Total costs of IAS in Europe summed to US$140.20 billion (or €116.61 billion) between 1960 and 2020, with the majority (60%) being damage-related and impacting multiple sectors. Costs were also geographically widespread but dominated by impacts in large western and central European countries, i.e. the UK, Spain, France, and Germany. Human population size, land area, GDP, and tourism were significant predictors of invasion costs, with management costs additionally predicted by numbers of introduced species, research effort and trade. Temporally, invasion costs have increased exponentially through time, with up to US$23.58 billion (€19.64 billion) in 2013, and US$139.56 billion (€116.24 billion) in impacts extrapolated in 2020. Importantly, although these costs are substantial, there remain knowledge gaps on several geographic and taxonomic scales, indicating that these costs are severely underestimated. We, thus, urge increased and improved cost reporting for economic impacts of IAS and coordinated international action to prevent further spread and mitigate impacts of IAS populations.

Ornamental horticulture is the primary pathway for invasive alien plant introductions. We critically appraise published evidence on the effectiveness of four policy instruments that tackle invasions along the horticulture supply chain: pre‐border import restrictions, post‐border bans, industry codes of conduct and consumer education. Effective pre‐border interventions rely on rigorous risk assessment and high industry compliance. Post‐border sales bans become progressively less effective when alien species become widespread in a region. A lack of independent performance evaluation and of public disclosure, limits the uptake and effectiveness of voluntary codes of conduct and discourages shifts in consumer preference away from invasive alien species. Policy implications. Closing the plant invasion pathway associated with ornamental horticulture requires government‐industry agreements to fund effective pre‐ and post‐border weed risk assessments that can be subsequently supported by widely adopted, as well as verifiable, industry codes of conduct. This will ensure producers and consumers make informed choices in the face of better targeted public education addressing plant invasions.

Climate change may strongly affect the abiotic conditions in riverine ecosystems, for example by changing water temperature regimes and salinisation due to sea water intrusion and evaporation. We analysed the effects of changes in water temperature and salinity on the species pool of freshwater molluscs in the river Rhine. Species sensitivity distributions (SSDs) for maximum temperature and salinity tolerance were constructed for native and non-native species that are currently present in the river Rhine. The maximum temperature tolerance was significantly higher for non-native mollusc species than native ones. For salinity tolerance, no significant difference was found between the two groups. The SSDs were used to determine the potentially not occurring fractions (PNOFs) of each species group corresponding with the yearly maximum water temperature and salinity levels recorded in (1) different river sections for the extreme warm and dry year 2003, and (2) the river Rhine at Lobith (The Netherlands) over the period 1960–2009. Changing temperature and salinity conditions in the river Rhine over the past 50 years corresponded with a net increase in PNOF for native species. This was mainly due to rising river water temperatures, which had a larger influence than decreasing salinity levels. For non-native species no change in PNOF was found, indicating that future temperature rise will disproportionally affect native mollusc species. Validation of the PNOF estimated for Lobith with the not occurring fraction (NOF) of mollusc species derived from monitoring data revealed similar trends for native as well as non-native mollusc species richness. The increase in the PNOF accounted for 14% of the increase in the NOF. The construction and application of SSDs appeared a promising approach to address the separate and combined effects of changing abiotic conditions on native and non-native species pools.