Ref: SF3-item4-doc2

Document prepared by NL and BE, clarifying "scoring of impacts", basis for Annex 2 in the Risk analysis methodology.

Impact scoring in risk assessments for listing invasive alien species of EU-concern

1.Introduction

In the 2nd meeting of the Scientific Forum (SF) for Invasive Alien Species (IAS) a discussion was held on the working document Risk assessment methodologyfor listing IAS of EU-concern, according to the EU Regulation 1143/2014 on the prevention and management of the introduction and spread of invasive alien species. The working document of the SF states that the following information is required in order for a risk assessment to comply with Art 5(1)(f) of this regulation:

  1. Describe and score known and potential future impact on biodiversity and related ecosystem services, with reference to:

-Native species, including red list species and species listed in the Birds and Habitats Directives.

-Protected sites, in particular Natura 2000.

-Endangered habitats, in particular habitats listed in the Habitats Directive.

-Ecosystem services.

  1. Describe known and potential future impact on human health, safety, and the economy.
  1. Clearly differentiate between known and potential impacts. Known impacts should be described for the EU and for third countries if relevant, potential impacts should be described for the EU only.

During the 2nd meeting of the SF it was agreed that further consideration should be given to:

-Good practices on reporting risk management information;

-Definitions of presence, establishment and widely-spread;

-Scoring of impacts in risk assessments.

During the 2nd SF meeting two relevant issues were discussed with respect to impact scoring of alien species:

-How to deal with different scoring systems in risk assessments for adverse impacts on biodiversity and related ecosystem services?

-What should be regarded as a significant adverse impact?

The representatives of NL and BE volunteered to prepare a discussion paper on the scoring of impacts in risk assessments.The present paper briefly describes 1) legal requirements for scoring impacts of IAS of EU concern, 2) Available scoring systems for adverse impacts of alien species on biodiversity and related ecosystem services, and 3) Cut-offvalues ofeffect scores representing significant adverse impacts on biodiversity and related ecosystem services. Consequences of different score systems and cut-off values for selecting IAS of EU concern are analysed. Finally, relevant discussion points for the SF and recommendations for further guiding of impact scoring in risk assessments are summarized.

2.Legal requirements for impact scoring

IAS should only be included on the Union list if they meet all criteria of the Regulation 1143/2014. According to Art 5(1)(f) the risk assessments must include a description of the adverse impact on biodiversity and related ecosystem services, including on native species, protected sites, endangered habitats, as well as on human health, safety, and the economy including an assessment of the potential future impact having regard to available scientific knowledge.

An important criterion for rating the score of impacts on biodiversity and related ecosystem services is(Art4-3c of Regulation 1143/2014): “They are, based on available scientific evidence, likely to have a significant adverse impact on biodiversity and related ecosystem services, and may also have an adverse impact on human health or the economy”

Moreover, article 4.6states: "(...) The Union list shall include as a priority those invasive alien species that (a) are not yet present in the Union or are at an early stage of invasion and are most likely to have a significant adverse impact and (b) are already established in the Union and have the most significant adverse impact."

3.Scoring systems for impacts of alien species

According to Roy et al. (2014), ENSARS,EPPO-DSS, GB-NNRA andHarmonia+are risk assessment protocols that most closely meet the minimum standards for listing ‘IAS of EU concern’. Below, the scoring systems of the EPPO-DSS, ENSARS, GB-NNRA and Harmonia+ are briefly described. In addition, the comprehensive framework of Blackburn et al. (2014) for Environmental Impact Classification for Alien Taxa (EICAT) has been included because it seems to be suitable for harmonizing impact scoring in risk assessments.

ENSARS

The European non-native species in aquaculture risk assessment scheme(ENSARS) of Copp et al. (2008) has been originally development for the EU for species listed in Annex IV of

EU Regulation on the use of aliens in aquaculture. Mostof the riskassessments with this protocol are appliedonly to UK oreven singleriver basins (Roy et al. 2014). ENSARS consists ofseven modules(Entry, Invasiveness,Organism, Facility,Pathway, SocioeconomicImpact,

Risk Summary &Risk Management)and uses a five point scalefor the impact assessments. The scores can besummarised by summation and conditionalprobability leading to ahigh, medium or low riskassignment of alien species.

EPPO DSS

The approach to assessing the environmental impact of alien plant pests and plants within the EPPO decision-support scheme has recently been revised (Kenis et al. 2012). The two main questions relating to environmental impacts remain essentially the same: ‘How important is the environmental impact caused by the pest within its current area of invasion?’ and ‘How important is the environmental impact likely to be in the area?’ Both questions have to be rated according to the five risk levels (minimal, minor, moderate, major, massive). The main questions are answered by a set of eight or nine sub-questions, covering the various aspects of environmental impacts. For each of these sub-questions, a rating is given based on three choices (low, medium, high) and rating guidance is provided as well as examples. Rating systems are presented to summarize the scores of the sub-questions into final scores for current and potential environmental impacts, by means of a hierarchy of risk matrices.

GB NNRA

The risk assessment scheme for non-native species inGreat Britain (GBNNRA) is a further developmentof the EPPO DSS scheme. In total, 80 questions relate toscreening the entry,establishment and spread (Y/N), and the impact(semi-quantitative five point scale withconfidencerecorded on a four point scale) of alien species. No detailed rating guidance is provided. The overall risk score iscalculated based on all ofthe scores given in theassessment and presentedin risk summary sheets ( Baker et al. 2008).

Harmonia+

In the online version of Harmonia+, questions on impacts of IAS can be answered with five alternative scores (i.e., not applicable, very low, low, medium, high) when cut-off values are precise or when two sub-questions become combined into one (D’hondt et al. 2015). In other cases three alternative scores are possible (low, medium, high).

Environmental impact is assessed through 4 questions addressing effects on the abundance of native species and 2 questions addressing impacts on ecosystem integrity and processes. Native species population declines are considered on the local scale: limited decline is considered as a (mere) drop in numbers; severe decline is considered as a (near) extinction. Similarly, limited ecosystem change is considered as transient and easily reversible; severe change is considered as persistent and hardly reversible. The following impact rating guidance is used:

-Low: at worst, the alien species causes limited population declines in species that are not of conservation concern (i.e red list, protected or keystone species) (species impacts) OR easily reversible process changes in ecosystems that are not of conservation concern.(ecosystem impacts);

-Medium: at worst, the alien species causes severe population declines in species that are not of conservation concern, or limited population declines in species that are of conservation concern (species impacts) OR hardly reversible process changes in ecosystems that are not of conservation concern, or easily reversible process changes in ecosystems that are of conservation concern (ecosystem impacts);

-High: at worst, the alien species causes severe population declines in species that are of conservation concern (species impacts) OR hardly reversible process changes in ecosystems that are of conservation concern (ecosystem impacts).

The Invasion score, Impact score and related uncertainty scores can be aggregated by taking the product yielding an ultimate score for the Invasion risk posed by the organism assessed. The protocol allows various approaches to calculate scores per risk category (average vs maximum) and to attribute different weight factors to risk categories. Guiding on cut-off levels for discrimination of IAS is not included.

EICAT

Hawkins et al. (2015) described a comprehensive framework and detailed guidelines for Environmental Impact Classification for Alien Taxa (EICAT), based on an earlier proposal Blackburn et al. (2014). Thisincludes a scoring system with five impact categories, reflecting an increase in the order of magnitude of the particular impact so that a new level of biological organization is involved (and the associated codes so that they increase alphabetically):

-Minimal Concern (MC),discernible impacts, but no effects on individual fitness of native species;

-Minor (MN), fitness of individuals reduced, but no impact on populations;

-Moderate (MO), changes to populations, but not to community composition;

-Major (MR), community changes, which are reversible;

-Massive (MV), irreversible community changes and extinctions.

The scores for a broad spectrum of impact categories are extensively defined in a guiding document.

Alien taxa should be classified based on the highest criterion level met across any of the impact mechanisms, for two timeframes: their highest environmental impact caused by the species to a recipient ecosystem anywhere in the World (Maximum Recorded Impact) and their current level of environmental impact on recipient ecosystems in the area under assessment(Current Impact).

Implications of different scoring systems

Thereviewed risk assessment methods remarkably differ in types of risk categories, numbers of questions on impacts of species and impact scoring systems, including uncertainty assessment and rating guidance (e.g., see also Table 1.4 in Roy et al. 2014). Particularly, differences in scoring systems may cause different outcomes of risk assessments of alien species (Verbrugge et al. 2012).

In our opinion, Blackburn et al. (2014) and Hawkins et al. (2015) developed a unifying classification system that may be used for harmonizing impact scores of alien species in risk assessments. Their EICAT framework seems to be suitable for further guiding on impactscoring of alien on biodiversity. Harmonia+ may also be suitable for this purpose.

It is worth noting that uncertainty is addressed in all presented systems with a ‘low-medium-high’ scoring scale. Uncertainty can be associated with lack of information, conflicting evidence, variation in impacts in space and time, and unclear formulations. Protocols differ in the way they consider or not these different elements. Guidance is more explicit in some protocols than in others.

Comprehensive frameworks for scoring impacts of IAS on protected sites (in particular Natura 2000), endangered habitats (in particular habitats listed in the Habitats Directive) and ecosystem services are still lacking.

4.Cut-off values for significant adverse impacts

Cut-off values for significant adverse impacts of alien species on biodiversity are not explicitly defined in the EU Regulation 1143/2014. In practice, various impact levels have been used to identify IAS of EU concern due to application of different scoring systems in risk assessments (e.g., yes/no approach, three vs five impact categories; various calculation methods for overall impact).

The term significant adverse impact is regarded to be synonymous with deleterious impact. According to Bartz et al. (2010) and Blackburn et al. (2014) a deleterious impact on biodiversity is defined as “an impact that changes the environment in such a way as to reduce native biodiversity or alter ecosystem functions to the detriment of the incumbent native species, as indicated by a change in importance or abundance following invasion”.

In case the SF decides to use the EICAT or the Harmonia+ framework for further guiding on impactscoring of alien species, it is recommended to consider cut-off values presented in Table 1 for assessing significant adverse impact on biodiversity. Two different cut-off values may be proposed that deserve further discussions within the SF.

Table 1.Cut-off value for significant impact adverse impact on biodiversity and the related ecosystem services in the EICAT and Harmonia+ systems.

Criteria in Regulation / EICAT / Harmonia+
Not yet present in the Union or at an early stage of invasion (less conservative approach for absent and emerging alien species) / Speciesare most likely to have a significant adverse impact / Moderate (MO) changes to populations of endangered species (i.e. decline), but not to community compositionor ≥ Major (MR)community changes, which are reversible and do not involve changes to populations of endangered species. / ≥ Medium rating for species and ecosystem impacts
Already established in the Union (more conservative approach for widespread alien species) / Species have the most significant adverse impact / ≥ Major (MR) changes (i.e. local extinction) of populations of endangered species. / High rating for species and ecosystem impacts

5.Recommendations

  • Use the unified classification of alien species / EICAT framework of Blackburn et al. (2014) andHawkins et al. (2015) or the Harmonia+ rating system of D’hondt et al. (2015) for further guiding on scoringimpact of alien on biodiversity in risk assessments.
  • Clearly define cut-off values for significant adverse impacts of alien species on native biodiversity based on alternatives presented in figure 1.
  • Explicitly integrate uncertainty in decision making. The uncertainty issue will require an additional analyses and in depth consideration. Addressing uncertainty is an important requirement to ensure scientific rigour of assessments and is particularly relevant as the listing of IAS of EU concern should be based on scientific evidence. This means high certainty for species that are already established in the Union and have the most significant adverse impact.
  • Develop a framework and guidelines for assessment and scoring impacts of alien species on protected sites (in particular Natura 2000), endangered habitats (in particular habitats listed in the Habitats Directive) and ecosystem services.

References

Baker, R., P. Hulme, G. H. Copp, M. Thomas, R. Black & K. Haysom, 2005. UK non-native organism risk assessment scheme user manual: version 3.3. Great Britain Non-native Species Secretariat, York.

Bartz, R., U. Heink & I. Kowarik, 2010. Proposeddefinition of environmental damage illustrated bythe cases of genetically modified crops andinvasive species. Conservation Biology 24: 675-681.

Blackburn, T.M., F. Essl, T. Evans, P.E. Hulme, J.M. Jeschke, I. Kuhn, S. Kumschick, Z. Markova, A. Mrugała, W. Nentwig, J. Pergl, P. Pysek, W. Rabitsch, A. Ricciardi, D.M. Richardson, A. Sendek, M. Vila, J.R.U. Wilson, M. Winter, P. Genovesi & S. Bacher, 2014. A unified classification of alien species based on the magnitude of their environmental impacts. PLoSBiol 12(5): e1001850. doi:10.1371/journal.pbio. 1001850.

Brunel, S., E. Branquart, G. Fried, J. van Valkenburg, G. Brundu, U. Starfinger, S. Buholzer,A. Uludag, M. Joseffson & R. Baker, 2010. The EPPO prioritization process for invasive alien plants. Bulletin OEPP/EPPO Bulletin 40: 407-422.

D’hondt, B., S. Vanderhoeven, S. Roelandt, F. Mayer, V. Versteirt, T. Adriaens, E. Ducheyne, G. San Martin, J-C. Grégoire, I. Stiers, S. Quoilin, J. Cigar, A. Heughebaert & E. Branquart, 2015. Harmonia+ and Pandora+: risk screening tools for potentially invasive plants, animals and their pathogens. Biological Invasions DOI 10.1007/s10530-015-0843-1.

Hawkins, C.L., S. Bacher, F. Essl, P.E. Hulme, J.M. Jeschke, I. Kühn, S. Kumschick, W. Nentwig, J. Pergl, P. Pyšek, W. Rabitsch, D.M. Richardson, M. Vilà, J.R.U. Wilson, P. Genovesi & T.M. Blackburn, 2015. Framework and Guidelines for Implementing the Proposed IUCN Environmental Impact Classification for Alien Taxa (EICAT). Diversity and Distributions 21: 1360-1363.

Kenis, M., S. Bacher, R.H.A. Baker, E. Branquart, S. Brunel, J. Holt, P.E. Hulme, A. MacLeod, J. Pergl, F. Petter, P. Pysek, G. Schrader, A. Sissons, U. Starfinger & U. Schaffner, 2012. New protocols to assess the environmental impact of pests in the EPPO decision-support scheme for pest risk analysis. Bulletin OEPP/EPPO Bulletin 42/1: 21-27.

Roy, H., K. Schonrogge, H. Dean, J. Peyton, E. Branquart, S. Vanderhoeven, G. Copp, P. Stebbing, M. Kenis, W. Rabitsch, F. Essl, S. Schindler, S. Brunel, M. Kettunen, L. Mazza, A. Nieto, J. Kemp, P. Genovesi, R. Scalera & A. Stewart, 2014. Invasive alien species – framework for the identification of invasive alien species of EU concern. Report ENV.B.2/ETU/2013/0026. Centre for Ecology & Hydrology, Wallingford.

Verbrugge, L.N.H., G. van der Velde, A.J. Hendriks, H. Verreycken & R.S.E.W. Leuven, 2012. Risk classifications of aquatic non-native species: application of contemporary European assessment protocols in different biogeographical settings. Aquatic Invasions 7/1: 49-58.

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