A prioritised list of invasive alien species of EU concern

Focusing on invasive species management, Carles Carboneras comments on the recent Policy Direction, A prioritised list of invasive alien species to assist the effective implementation of EU legislation, published in Journal of Applied Ecology and recently featured by BBC News.

Alien organisms can cause significant disruption when introduced into a new environment and, for that reason, effective policies on invasive species aim at preventing their introduction and spread in the first place. The Convention on Biological Diversity recommends tackling new invasions in the earliest stage possible, preferably even before they take place, to achieve the best ecological and economical results and – generally speaking – before it is too late. It is best practice to compile all the evidence on the species biology, its potential harm, pathways of introduction, management measures and associated costs in a so-called ‘risk assessment’. The 2014 Regulation on invasive alien species establishes that a risk assessment must be completed before any organism can be added to the list of invasive alien species of European Union concern, and therefore before it can be banned from being imported, kept, sold or released into the EU.

Why prioritise?

The problem is that developing pivotal risk assessments takes considerable time and effort, and the number of introduced species already in the EU or that might be introduced in the future is very large. The DAISIE database contains information on 12,000 species already present in Europe and Vilà et al. (2010) estimate that 1,100 may cause ecological impacts whilst 1300+ can produce economical damage. Invasion biologists and policymakers are thus facing a huge workload, not least because the development of risk assessments in the past has been undertaken by national authorities possibly following pressures or opportunities, but there is no record of any EU-wide attempt to systematically select and species for risk assessment. At the present rate of 12-15 risk assessments every year, it would take over a century to go through the various hundreds of potential species, so there is a clear need to upscale and prioritise.

A multidisciplinary group of scientists and policy specialists, led by the RSPB and BirdLife International, have developed the first systematic approach to selecting species for risk assessment on a European scale. The first step was to develop a decision tree in order to identify which species filled the criteria for listing, according to the stipulations of the EU IAS Regulation. Then, a literature search focusing on the major databases with information on invasive species in Europe, produced a total of 1323 species of all taxa known to be present in Europe already or with the potential of being introduced in the future. Of those, 900 species filled the requirements for listing under the EU IAS Regulation (see figure 1).

At least 50 risk assessments every year

We used our expert opinion, and the information contained in the databases and available literature, to assess each of the 900 species according to two criteria: their maximum reported impact (following the criteria of the new EICAT classification of impact, promoted by the IUCN) and their invasion history in Europe. We put that information on an ‘impact x distribution’ matrix, and used it to recommend which species should be considered for risk assessment in a ranked order of priority along the following timeline: 2018 (59 species), 2020 (148 spp.), 2025 (336 spp.) and 2030 (357 spp.).

Putting a species through risk assessment does not imply that it will be listed immediately, because adding species on the list of EU concern is an independent process that requires agreement among the EU Member States following a proposal by the European Commission. The risk assessment might also reach the conclusion that the costs associated with listing of a particular species outweigh the benefits of banning it from the EU territory. All those aspects lie beyond the scope of our preliminary evaluation.

Breakdown of the 900 species recommended for risk assessment, grouped by taxonomic group and pathway of introduction. (Carboneras et al. 2017 – doi:10.1111/1365-2664.12997)

Upscale and prioritise

Where our contribution makes a difference is in estimating the number of risk assessments that are needed, in line with the magnitude of the threat, and in proposing a ranked order of priority of species for risk assessment within a relatively narrow timeframe. Our message is that there is a lot of work to be done, and that the European Commission, the national authorities and the scientific community need to think strategically and to operate quickly.

Our work may also help identify the required funding sources and relevant amounts to be mobilised, both at EU and national level. The European Commission website proposes supporting action on invasive alien species through its existing financing instruments, LIFE, Horizon 2020, Rural Development 2014-2020 and Regional Development funding. The availability of EU and national funding to carry out enough risk assessments over the next few years is crucial for the ultimate success of the 2014 Regulation on invasive alien species (set to be reviewed in 2021), because it will determine the capacity to deliver suitable policies, and therefore to prevent further damage to biodiversity, the economy and well-being in the EU.

The full Policy Direction, A prioritised list of invasive alien species to assist the effective implementation of EU legislation is available as an Open Access article in Journal of Applied Ecology.

Find out more about the article and the team behind it on the British Ecological Society website.

3 thoughts on “A prioritised list of invasive alien species of EU concern

    1. This is a good point, as previous exercises focusing on “100 of the World’s Worst Invasive Alien Species” (http://www.iucngisd.org/gisd/100_worst.php) or “100 of the Worst” in Europe (http://www.europe-aliens.org/speciesTheWorst.do) have been very successful in raising public awareness.

      However, our exercise only attempted to carry out a limited assessment of the impact of invasive species on biodiversity, based on the published information contained in databases and in literature. We did not consider the full impact, as this needs to be estimated in the proper risk assessments (in the order) that we propose.


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