Download Scoring the impacts of established non

Scoring the impacts of established non-native species in GB (briefing
document)
Lead:

Helen Roy (CEH/GB-NNSIP) and Olaf Booy (NNSS / Newcastle University)
Groups (bold = group leader, italics = unconfirmed):
 Plants
o Attending: Kevin Walker, Oliver Prescott, Katharina Dehnem-Schmutz, Trevor Dines,
Pablo Gonzalez-Moreno

Terrestrial invertebrates
o Attending: Dick Shaw, Alan Stewart , Chris Raper, Martin Harvey, Karsten
Schonrogge

Freshwater animals
o Attending: David Aldridge (inverts), Ian Winfield (fish), Rob Britton (fish), Colin Bean
(fish), Alison Dunn (inverts), Paul Stebbing (inverts)

Vertebrates
o Attending: David Noble, Tim Blackburn, Dave Parrot, Pete Robertson, Aileen Mill
o Scoring but not attending: John Marchant, Kirsty Park, Jim Foster, Robbie McDonald,
Trent Garner, John Wilkinson

Marine
o Attending: Jack Sewell , Elizabeth Cook, Paul Stebbing, Christine Maggs, Francis
Bunker, Roger Herbert, Juliet Brodie, Esther Hughes
o Scoring but not attending: John Bishop
Other contributors:
 Steph Rorke (CEH), Niall Moore (NNSS) and Emma Deighton (Defra)
Aim
To score the biodiversity impact of each established non-native species in Great Britain.
Method
Species selection: There are c. 2000 established non-native species in GB; screening will be used to
refine the number to be assessed. The NNSIP team have already provided a rapid assessment of
impact, which identified 169 species that have a negative or strong negative ecological impact and
90 additional species that have unknown ecological impact. This will form the basis of the list of
species to be assessed. In addition, the NNSS will propose additional species on the basis of a review
of existing lists (e.g. WFD, MSFD, etc.), risk assessments and key literature. The proposed list will be
sent to expert groups, along with the remaining list of negligible impact species for experts to double
check. The final list will be those agreed as a result of this process.
Expert groups: Experts will be organised into the five thematic groups above, each of which will be
led by one or two people (bold) and will comprise approximately five experts in total. Each group
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leader will be provided with a list of species to assess based on their group’s expertise. The lead will
be responsible for dividing species among the group for assessment. Each species will be assessed
(see separate guidance) independently by >3 experts in the group. The median score from these
assessments will be used as the final score for each species, which will then be considered and
agreed by the whole expert group.
Consensus workshop: Once initial scores have been agreed within the expert groups, they will form
the basis of a consensus building workshop. Expert leads will be invited to attend an afternoon
session to review the impact assessment process, refine scores and agree the approach for the main
workshop. All experts will then be invited to attend the main, day long, workshop at which scores
will be presented by the taxonomic leads based on the impact categories (i.e. massive impact, major
impact, etc.). Focus will be on the species at the edges of each category to determine whether they
should be moved up or down respectively; confidence scores will also help to indicate whether a
species should potentially move its position. Leads will not be expected to present on all species;
instead they should highlight areas of uncertainty or disagreement in the scoring of their species.
The first session of this day will be to review, discuss and refine lists presented back from each
expert group. The second and final session will be to integrate all species into one list, which will be
reviewed by the whole group with the aim of agreeing by consensus the final position of each
species with the impact categories.
Output
The process and scores will be written up as a peer reviewer paper.
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Annex 1. Guidance for scoring species impact
Note more detailed instructions for assessors on the use of the Access scoring database is provided
separately (see document: Invasive non-native species impact scoring - instructions for assessors).
i.
For each species, experts should use their best judgement to provide response scores for current
impact and maximum potential impact. EICAT categories (Box 1 and Figure 1) will be used to
score impact; further guidance on the EICAT scheme is available in the attached document
(http://onlinelibrary.wiley.com/store/10.1111/ddi.12379/asset/supinfo/ddi12379-sup-0001AppendixS1.docx?v=1&s=111344d9f95d9a706cb3e161eb42fddd1d6cefe3).
Current impact is defined as the impact to date based on the species current distribution in GB.
Maximum potential impact is defined as the impact the species would be expected to have in GB
if it were established in all parts that are suitable (i.e. based on current biotic and abiotic
conditions).
ii.
Where there is uncertainty in the response scores, this should be reflected in separate
confidence scores (Box 2).
iii.
The type of impact caused by the species should also be recorded. This is based on the
maximum potential impact and is divided into three main impact types:
 Impact on species not listed as of conservation concern;
 Impact on habitats not listed as of conservation concern;
 Impacts on species of conservation concern;
 Impacts on habitats of conservation concern;
 Impacts on ecosystem function.
A list of species and habitats of conservation concern is provided at Box 3.
iv.
A tick box is used to record impact mechanism (i.e. competition, predation, hybridization,
disease transmission, parasitism, poisoning / toxicity, bio-fouling, grazing / herbivory / browsing,
interactions with other IAS, modification to nutrient cycling, physical modification of the habitat,
modification of natural succession, disruption of food webs). Multiple boxes can be checked.
v.
The type of evidence used to determine the response should be recorded, selecting from the
following predefined responses: field observation, experiment, modelling, expert opinion.
vi.
A supporting comment should be provided to justify the main response scores in particular the
EICAT categories chosen. Where there are impacts on species / habitats of conservation
concern, ideally these should be listed here.
vii.
To double check the information already in the NNSIP system, assessors should also flag species
for which there are negative socio-economic consequences using the tick box provided.
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Box 1. EICAT Categories (extract from paper
http://onlinelibrary.wiley.com/store/10.1111/ddi.12379/asset/supinfo/ddi12379-sup-0001AppendixS1.docx?v=1&s=111344d9f95d9a706cb3e161eb42fddd1d6cefe3)
Minimal Concern (MC)
A taxon is considered to have impacts of Minimal Concern when it is unlikely to have caused
deleterious impacts on the native biota or abiotic environment. Note that all alien taxa have impacts
on the recipient environment at some level, for example by altering species diversity or community
similarity (e.g. biotic homogenisation), and for this reason there is no category equating to “no
impact”. Taxa that have been evaluated under the EICAT process but for which impacts have not
been assessed in any study should not be classified in this category, but rather should be classified as
Data Deficient.
Minor (MN)
A taxon is considered to have Minor impacts when it causes reductions in the fitness of individuals in
the native biota, but no declines in native population sizes, and has no impacts that would cause it to
be classified in a higher impact category.
Moderate (MO)
A taxon is considered to have Moderate impacts when it causes declines in the population size of
native species, but no changes to the structure of communities or to the abiotic or biotic
composition of ecosystems, and has no impacts that would cause it to be classified in a higher
impact category.
Major (MR)
A taxon is considered to have Major impacts when it causes the local or population extinction of at
least one native species, and leads to reversible changes in the structure of communities and the
abiotic or biotic composition of ecosystems, and has no impacts that cause it to be classified in the
MV impact category.
Massive (MV)
A taxon is considered to have Massive impacts when it leads to the replacement and local extinction
of native species, and produces irreversible changes in the structure of communities and the abiotic
or biotic composition of ecosystems. Note that ‘‘local’’ refers to the typical spatial extent over which
the original native communities can be characterised.
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Figure 1. A decision chart showing how the EICAT categories should be applied (extract from Hawkins et al
2016)
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Box 2. Scoring confidence (extract from Hawkins et al 2016)
Confidence is scored for each impact score and the overall score, following Blackburn (modified
from the EPPO pest risk assessment decision support scheme (Alan MacLeod 09/03/2011; revised
28/04/2011; copied from CAPRA, version 2.74; 2)).
Confidence Score
Examples
High
There is direct relevant observational evidence to support the assessment;
and
Impacts are recorded at the typical spatial scale over which original native
communities can be characterized;
and
There are reliable/good quality data sources on impacts of the taxa;
and
The interpretation of data/information is straightforward;
and
Data/information are not controversial or contradictory.
There is some direct observational evidence to support the assessment, but
some information is inferred;
and/or
Impacts are recorded at a spatial scale which may not be relevant to the scale
over which original native communities can be characterized, but extrapolation
or downscaling of the data to relevant scales is considered reliable, or to
embrace little uncertainty;
and/or
The interpretation of the data is to some extent ambiguous or contradictory.
There is no direct observational evidence to support the assessment, e.g. only
inferred data have been used as supporting evidence;
and/or
Impacts are recorded at a spatial scale which is unlikely to be relevant to the
scale over which original native communities can be characterized, and
extrapolation or downscaling of the data to relevant scales is considered
unreliable or to embrace significant uncertainties.
and/or
Evidence is poor and difficult to interpret, e.g. because it is strongly ambiguous.
and/or
The information sources are considered to be of low quality or contain
information that is unreliable.
Medium
Low
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