A new approach to horizon-scanning: identifying potentially invasive alien species and their introduction pathways

Invasive alien species (IAS) are considered an important threat to global biodiversity due to major ecological impacts. In 2014, the European Union (EU) introduced a regulation (EU) No 1143/2014 on the prevention and management of the introduction and spread of IAS. The first risk prioritized list of IAS of EU concern was adopted on the 3rd of August 2016. EU member states are required within 18 months to carry out a comprehensive analysis and prioritisation of the pathways of unintentional introduction and spread of these IAS in their territory. Horizon-scanning is a method of IAS prioritisation through the systematic analysis of potential future IAS and identification of new opportunities for IAS management. However, horizon-scanning has mostly been applied on a national basis only, leading to a fragmented approach within the EU and ignoring the potential for IAS to cross international borders. We present a novel framework for horizon-scanning applicable at a continental scale. Our method maximises the use of available data from climatically matched countries by applying a harmonisation and aggregation method, and elucidates the relationship between pathways, impact types and species groups for risk prioritised IAS. Application of the method produced a list of potential IAS for the Netherlands revealing that the international trade in plants and animals is the most important pathway for the introduction of IAS. The horizon-scanning provided a starting point for the design of preventative, early identification and rapid action measures for the effective management of potential IAS.