Abstract
Ireland, being an island situated on Europe’s western seaboard, has a fewer number of native species than mainland European Union Member States (MS). Increased numbers of vectors and pathways have reduced the island’s biotic isolation, increasing the risk of new introductions and their associated impacts on native biodiversity. It is likely that these risks are greater here than they are in continental MSs, where the native biodiversity is richer. A horizon scanning approach was used to identify the most likely invasive alien species (IAS) (with the potential to impact biodiversity) to arrive on the island of Ireland within the next ten years. To achieve this, we used a consensus-based approach, whereby expert opinion and discussion groups were utilised to establish and rank a list of 40 species of the most likely terrestrial, freshwater and marine IAS to arrive on the island of Ireland within the decade 2017–2027. The list of 40 included 18 freshwater, 15 terrestrial and seven marine IAS. Crustacean species (freshwater and marine) were taxonomically dominant (11 out of 40); this reflects their multiple pathways of introduction, their ability to act as ecosystem engineers and their resulting high impacts on biodiversity. Freshwater species dominated the top ten IAS (seven species out of ten), with the signal crayfish (Pacifastacus leniusculus) highlighted as the most likely species to arrive and establish in freshwaters, while roe deer (Capreolus capreolus) (second) and the warm-water barnacle (Hesperibalanus fallax) (fifth), were the most likely terrestrial and marine invaders. This evidence-based list provides important information to the relevant statutory agencies in both the Republic of Ireland and Northern Ireland to prioritise the prevention of the most likely invaders and aid in compliance with legislation, in particular the EU Regulation on Invasive Alien Species (EU 1143/2014). Targeted biosecurity in both jurisdictions is urgently required in order to manage the pathways and vectors of arrival, and is vital to maintaining native biodiversity on the island of Ireland.
Highlights
Invasive alien species (IAS) are widely recognised as one of the greatest threats to biodiversity, through their interactions with other drivers of change (Millenium Ecosystem Assessment 2005; Vilá et al 2011; Blackburn et al 2015; Dick et al 2017; IPBES 2019)
The workshop applied a horizon scan process to forecast IAS arrival, establishment and impact for the island of Ireland and was attended by experts from the Republic of Ireland, Northern Ireland, and Great Britain. These experts were selected from a range of disciplines in order to provide a balance of expertise throughout terrestrial, freshwater and marine taxa
The top forty IAS most likely to arrive, establish, spread and cause impacts to biodiversity on the island of Ireland are shown in Table 1, with a summary profile for each of the top ten species available in supplementary material Appendix 1
Summary
Invasive alien species (IAS) are widely recognised as one of the greatest threats to biodiversity, through their interactions with other drivers of change (Millenium Ecosystem Assessment 2005; Vilá et al 2011; Blackburn et al 2015; Dick et al 2017; IPBES 2019). Predicting the arrival, establishment, spread and impact of IAS to any region is a challenging task; establishing a list of likely candidate species is a vitally important first step in complying with legislation (EU 2014) and mitigating the environmental and economic impacts associated with an established IAS This information can be promptly used to direct policy and target resources, on a national or cross-jurisdictional level, towards prevention, early detection and rapid response for the most impactful IAS. The workshop applied a horizon scan process to forecast IAS arrival, establishment and impact for the island of Ireland (both jurisdictions) and was attended by experts from the Republic of Ireland, Northern Ireland, and Great Britain These experts were selected from a range of disciplines (scientific researchers, practitioners and responsible authorities) in order to provide a balance of expertise throughout terrestrial, freshwater and marine taxa
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