Study on Invasive Alien Species – Development of Risk Assessments: Final Report (year 1) - Annex 2: Risk assessment forChrysemys picta
Study on Invasive Alien Species –
Development of risk assessments to tackle priority species and enhance prevention
Contract No 07.0202/2016/740982/ETU/ENV.D2
Final Report
Annex 2: Risk Assessment forChrysemys picta (Schneider, 1783)
Risk assessment template developed under the "Study on Invasive Alien Species – Development of risk assessments to tackle priority species and enhance prevention" Contract No 07.0202/2016/740982/ETU/ENV.D2Based on the Risk Assessment Scheme developed by the GB Non-Native Species Secretariat (GB Non-Native Risk Assessment - GBNNRA)
Name of organism: Painted turtle Chrysemys picta(Schneider, 1783)
Author(s) of the assessment:
- Riccardo Scalera, IUCN SSC Invasive Species Specialist Group, Rome, Italy
- Wolfgang Rabitsch, Umweltbundesamt, Vienna, Austria
- Tim Adriaens, Research Institute for Nature and Forest (INBO), Brussels, Belgium
- Peter Robertson, Newcastle University, Newcastle, Great Britain
- Dan Chapman, Centre for Ecology and Hydrology (CEH), Wallingford, Great Britain
Peer review 1: Olaf Booy, GB Non-Native Species Secretariat, Animal and Plant Health Agency (APHA), York, Great Britain
Peer review 2: Peter Paul van Dijk, Global Wildlife Conservation, Austin, USA
This risk assessment has been peer-reviewed by two independent experts and discussed during a joint expert workshop. Details on the review andhow comments were addressed are available in the final report of the study.
Date of completion: 17/11/2017
RISK SUMMARIES
RESPONSE / CONFIDENCE / COMMENT
Summarise Entry / Very likely / high / The species is already present in some EU countries, and records of occurrence exist in the Alpine, Atlantic, Continental and Mediterranean regions.
In current conditions, the overall likelihood of entry into the EU based on the Pet/aquarium/terrarium pathway (escape from confinement) is minimal, due to the existing trade ban following the implementation of the EU Wildlife Trade Regulations. It is essential that a trade ban is sustained, either by Regulation 1143/2014 or by the EU Wildlife Regulations. Should the trade suspension be removed, the likelihood of the species being traded and subsequently introduced into or within the EU in large numbers may increase.
Summarise Establishment / likely / low / In current conditions, the overall likelihood of establishment in the EU is likely. However, there are currently no signs of establishment of permanent populations in Europe.Based on the species distribution model, which does show considerable associated uncertainties despite the peculiar ecological flexibility of the species, this risk is higher for Atlantic, Black Sea, Continental, Mediterranean, Pannonian, and Steppic regions, while for Alpine and Boreal regions is moderate.
Summarise Spread / very slowly / low / The overall likelihood of unaided spread of C. picta into or within any biogeographical region is low, because no information was found on the occurrence of C. picta outside the EU and only casual occurrences are known from within the EU.
Summarise Impact / moderate / low / In Europe, C. pictamay be expected to have a moderate impact on biodiversity and ecosystem services, as well as on human well-being, should the species establish and spread. The main potential impacts are competition with native turtle species (for food and basking places), the possible transmission of pathogens and diseases to wildlife and humans, and possible effects on ecological trophic webs. However, the confidence of this assessment is considered low due to lack of documented evidence of impact of this species outside its native range.
Conclusion of the risk assessment / low / low / The result of the risk assessment is affected by the lack of information about the species ecology outside its native range, which may possibly be due to its minimal invasive potential. So far the species has not established in the EU, probably thanks to the trade suspension implemented through the EU wildlife Trade Regulation.
Distribution Summary(for explanations see EU chapeau and Annex IV):
Member States
Recorded / Established (currently) / Established (future) / Invasive (currently)Austria / Yes / – / Yes / –
Belgium / Yes / – / Yes / –
Bulgaria / – / – / Yes / –
Croatia / – / – / Yes / –
Cyprus / – / – / - / –
Czech Republic / – / – / Yes / –
Denmark / – / – / - / –
Estonia / – / – / - / –
Finland / – / – / - / –
France / – / – / Yes / –
Germany / Yes / – / Yes / –
Greece / – / – / Yes / –
Hungary / – / – / Yes / –
Ireland / – / – / Yes / –
Italy / Yes / – / Yes / –
Latvia / – / – / - / –
Lithuania / – / – / Yes / –
Luxembourg / – / – / Yes / –
Malta / Yes / – / - / –
Netherlands / – / – / Yes / –
Poland / – / – / Yes / –
Portugal / – / – / Yes / –
Romania / – / – / Yes / –
Slovakia / – / – / Yes / –
Slovenia / – / – / Yes / –
Spain / Yes / – / Yes / –
Sweden / – / – / Yes / –
United Kingdom / Yes / – / Yes / –
EU biogeographical regions
Recorded / Established (currently) / Established (future)Alpine / Yes / – / Yes
Atlantic / Yes / – / Yes
Black Sea / – / – / Yes
Boreal / – / – / Yes
Continental / Yes / – / Yes
Mediterranean / Yes / – / Yes
Pannonian / – / – / Yes
Steppic / – / – / Yes
ANNEX I - Scoring of Likelihoods of Events 45
ANNEX II - Scoring of Magnitude of Impacts46
ANNEX III - Scoring of Confidence Levels 47
ANNEX IV - Species Distribution Model 48
ANNEX V - Evidence on measures and their implementation cost 64
EU CHAPEAUQUESTION / RESPONSE / COMMENT
Ch1. In which EU biogeographicalregion(s) or marine subregion(s) has the species been recorded and where is it established? / The species is not considered established in any EU biogeographical region, but there are records of occurrence in the Alpine, Atlantic, Continental and Mediterranean regions. / According to Peter Paul van Dijk (pers. comm. 2017) with long-lived specimens, that are widely traded and available in the pet trade, it is always a challenge differentiating whether the records of escaped or released pets are casual occurrences or established populations. In fact, summer incubation conditions (sustained soil warmth to adequately incubate eggs) in the Alpine, Atlantic and Boreal zones are unlikely to be adequate for more than exceptional, occasional reproduction, with recruitment being unlikely. In its native range in north America, this is primarily a species of continental climates, and it is marginal in its occurrence in Oregon, Washington State and British Columbia. On the other side, Chrysemys picta in general is a species associated with permanent wetlands, not with waterbodies that regularly dry out (animals may move to temporary ponds near permanent waterbodies, but permanent water within easy walking distance seems to be a survival prerequisite). Therefore the establishment of the species in the Mediterranean climate may be affected by the lack of suitable habitats.
Ch2. In which EU biogeographical region(s) or marine subregion(s) could the species establish in the future under current climate and under foreseeable climate change? / According to a Species Distribution Model based on occurrence and ecological data from the native and non-native range (see Annex IV), those Biogeographical Regions predicted to be most suitable in the current climate are the Pannonian, Mediterranean, Steppic, Black Sea, and Continental. In addition, the Anatolian region is suitable. Climate change is predicted to increase suitability in the Continental, Black Sea, Atlantic and Alpine regions, but decrease suitability in the Mediterranean and Steppic regions (see Annex IV for details). / See comments in Ch.1 in relation to the need for adequate summer soil heat for incubation – exceedingly unlikely in Atlantic and Boreal regions, and highly unlikely in the Alpine.
Ch3. In which EU member states has the species been recorded? List them with an indication of the timeline of observations. / The species was recorded in at least six EU countries Germany, Austria, UK, Malta, Spain (Kraus 2009) and Italy (Scalera R. 2017, pers. observation).
Earliest casual observations in Europe date back to 1905 in Great Britain(Kraus 2009). / In Germany there are reports about the occurrence of the species (Nehring et al. 2015,Geiter et al. 2002, Winkel et al. 2000, Nobanis 2007, Fritz and Lehmann 2002), including itssuccessful reproduction in the wild in 2002, in Baden-Württemberg, central Germany (Adrados and Briggs 2002, Fritz and Lehmann 2002).
In Spain there are scattered records of the species presence invarious localities of Castellón (Campos-Such 2016), Cataluña (Pleguezuelos 2002, Filella et al. 1999, MAGRAMA, 2013; SIARE, 2016), and inthe Basque Country (Patiño-Martínez and Marco, 2005). According to Pinya and Carretero (2011) its presence has been reported also in the Balearic islands (s’Albufera de Mallorca Natural Park) but its reproduction is not confirmed.
There is one confirmed record in Austria (Lower Austria in 2009) (Kleewein A., pers. comm. 2017).
There are a few casual records of C. picta in Belgium (Adriaens et al. 2016).
In Italy the species was recorded in Rome (Riccardo Scalera, 2017, pers. observ.). Also, the birth of an overwintering hatchling in semi-natural conditions was reported (but details to assess the presence of elements of husbandry and breeding support which may have facilitated to the event are not availablesee
In the UK, the species was introduced in early 1905 in Surrey (some specimens may have survived for 40 years). In 1945 the same species (probably)was introduced in Middlesex (Fitter 1959, Frazer 1964). There are reports about the species being recently seen in the London area (Langton et al. 2011).In general, the fact that the species has not persisted may be indicative of its poor ability to persist in Atlantic climates.
In Malta the species was released in a garden over 100 years ago (Despott 1913) but no further records have ever been collected.
Ch4. In which EU member states has this species established populations? List them with an indication of the timeline of establishment and spread. / There are currently no established populations in any EUMember States. / Although the species did successfully breed in the Continental regionno information was found about the current persistence of any population in the wild.
Ch5. In which EUmember states could the species establish in the future under current climate and under foreseeable climate change? / Among all North American freshwater terrapinsthis species has one of the largest native distributions and is well adapted to different climates and might have excellent survival capabilities in the wild in Europe(Adrados and Briggs 2002). However, its ability to reproduce successfully in a European environment under current climatic conditions is still poorly understood and needs to be investigated further.
A comprehensive analysis ofsuitability for potential establishment of C. pictain Europe, under current and predicted future climatic conditions was made for the purpose of this risk assessment by Chapman (2017 unpublished report). The results of the study show that under current climate conditions the species may become established in most of EU Member States, with the exception of Sweden, Finland, Denmark, Latvia, Estonia, and Ireland.
Under future foreseeable climate change the species could become established also in Sweden, Latvia, Estonia and Ireland, whilelikelihood may decrease in Mediterranean countries,such as Cyprus, Malta, Greece, Spain and Portugal. / According to a 2002 report (Adrados andBriggs 2002) the species might survive in large parts of Europe.In particular, considering the large geographical distribution range in the USA, the risk of establishment for C. picta(based only on temperature and altitude data from its native range) is high in southern and central parts of Europe and low in the northern parts of Europe (Adrados and Briggs 2002).
Ch6. In which EU member states has this species shown signs of invasiveness? / There are currently no indications of invasiveness of the species in the EU from the information found. / Chrysemys pictawas considered as potentially invasive in Spain in a preliminary list drafted by Capdevila-Argüelles andZilletti (2001). Also Da Silva (2002) mentioned the possibility that in Spain C. picta may compete for food and space with the native terrapin Mauremys leprosa, although this was not validated.
In Germany, the risk assessment resulted in the “Potentially invasive – Watch List” category (Nehring et al. 2015). The main identified threat was competition for resources with the native pond slider Emys orbicularis.
Ch7. In which EU member states could this species become invasive in the future under current climate and under foreseeable climate change? / Under future foreseeable climate change the species could become invasive wherever it is established (see Qu. Ch5).
SECTION A – Organism Information and Screening
Organism Information / RESPONSE / COMMENT
A1. Identify the organism. Is it clearly a single taxonomic entity and can it be adequately distinguished from other entities of the same rank? / This species has several sub-species. The status of one sub-species (C. p. dorsalis) has been debated, but is included within C. pictain this assessment. Excellent sources are available to distinguish this species from others (e.g. Fritz and Havas 2007).
Scientific name:Chrysemys picta(Schneider, 1783)
Taxonomy:
Class: Reptilia
Order: Testudines
Family: Emydidae
Genus: Chrysemys Gray 1944
Synonyms:
Chrysemys dorsalis Agassiz, 1857
Chrysemys marginata Agassiz, 1857
Chrysemys treleasei Hurter, 1911
Emys bellii Gray, 1830
Emys oregoniensis Harlan, 1837
Testudo picta Schneider, 1783
Hydrochelys picta [= Testudo picta Schneider 1783]
Emys (Chrysemys) picta Schweigger [= Testudo picta
Schneider 1783]
Common names: painted turtle
German: Zierschildkröte / As summarised by Seidel and Ernst (2017) Ernst and Lovich (2009)andVan Dijk (2011), Chrysemys pictais traditionally considered to include four subspecies:
C. p. picta (Schneider, 1783)
C. p. bellii(Gray, 1831)
C. p. dorsalisAgassiz, 1857
C. p. marginataAgassiz, 1857
The taxonomy of the genus Chrysemys has been the object of several works and discussions, given the similarities with the closely related genera Trachemys and Pseudemys (for a review see Seidel and Ernst 2017, Ernst and Lovich 2009). For example,Starkey et al. (2003) argued thatC. dorsalis (Agassiz, 1857) should be elevated to species status (see also Turtle Taxonomy Working Group 2017), however the taxonomy of C. dorsalis remains debatable (Uetz and Hallermann, 2017). Therefore for the present assessment, the traditional arrangement ofpicta,bellii,dorsalis andmarginataas subspecies ofpictais retained (Fritz and Havaš2007).
Chrysemys subspecies do naturally hybridize where their native ranges overlap (e.g. Ernst et al. 2014), and examples of genetic pollution caused by abandoned petturtles (i.e. Chrysemys picta bellii from British Columbia introgressed by non-native subspecies) are documented (Jensenet al. 2014).
A2. Provide information on the existence of other species that look very similar / The species may be confused with a number of other freshwater turtles alien to Europe, particularly belonging to the closely relatedgenera Trachemys and Pseudemys(although there are morphological features which may provide good diagnostic hints to the expert eye). This may lead to obvious problems of misidentification and misreporting. For example, in a recent study on the distribution and biogeography of amphibians and reptiles of Europe (Silliero et al. 2014), the authors warn that the records of Trachemys scripta might also include records of introduced specimens of other Trachemys species or even related genera (e.g. Chrysemys picta). Also according to Kraus (2009) there are records of Trachemys scripta in Germany which have been misreported as Chrysemys picta.
This may create bias in the information about the actual species occurrence, particularly outside its native range. Some identification problems with native freshwater turtles of the family Emididea (i.e. Emys orbicularis, Mauremys spp.) may also occur. / According to Peter Paul van Dijk (pers. comm. 2017) in the field in the native range (USA) this species is identifiable from significant distances, thanks to its characteristic low, very smooth shell and pretty distinctive face and carapace patterning.
A3. Does a relevant earlier risk assessment exist? (give details of any previous risk assessment and its validity in relation to the EU) / No comprehensive risk assessments are known for the species.
However, a computed establishment risk model was made for some species of turtles imported to the EU (Kopecký et al 2013). The risk attributed to C. picta, on the basis of parameters such as climate match, species’ ability to establish populations elsewhere, and establishment success of other species from the same family, is moderate (score: 0.34).
Also, it is worth noting that a thermo-hypsometric distribution risk-map (based only on temperature and altitude data from its native range) was made by Adrados and Briggs (2002). The selection criteria for C. picta were the number of months average temperature > 15°C > 3.40 and the number of months average temperature > 15°C >6.14 (plus an altitude of 1940 m). Other key factors/parameters, e.g. precipitation, humidity, soil conditions and plant cover, were not taken into account. The map illustrates the high risk in southern and central parts of Europe, and low risk in northern parts.
In Germany, the risk assessment resulted in the “Potentially invasive – Watch List” category (Nehring et al. 2015). The main identified threat was competition for resources with the native pond slider Emys orbicularis. The assessment is still valid for Germany. / The need for a specific risk assessment based on ecological research for the species was suggested as early as 2002 by Adrados and Briggs (2002), who assessed that C. pictais most likely to adapt better to different climates than any other species assessed, and sosurvives better in the wild in Europe. On the basis of the high potential threat Adrados and Briggs (2002) also recommended undertaking immediate action wherever the species had established reproducing populations in the wild in Europe.
Regarding potential competition with the native pond slider Emys orbicularis, it is worth keeping in mind that in its native range Chrysemys pictacoexists, although it is usually less dominant, in direct sympatry (in the same wetlands) with close relatives of Emys orbicularis, i.e. Emydoidea blandingii and Actinemys marmorata / pallida (both occasionally placed in genus Emys)(Peter Paul van Dijk, pers. comm. 2017).
A4. Where is the organism native? / Chrysemys pictais a native to North America, where it is one of the most widespread and abundant turtle species (Van Dijk2011).In fact this species is the only American turtle that naturally occurs across the continent, from southern Canada, to Mexico (Chihuahua), across the US (for details see Ernst and Lovich 2009, Van Dijk 2011).
As summarised by Ernst and Lovich (2009) Chrysemys picta prefers slow-moving shallow-water habitats with soft bottoms, aquatic vegetation, and abundant basking sites, such as lakes, ponds, swamps, marshes, sloughs, drainage ditches, rivers, oxbows, and creeks (including water bodies subject to annual drying). It usually avoids waters with fast currents, and is fairly tolerant of polluted waters. Moreover, the species occupies habitats with sand dunes, brackish waters, backwaters, open waters and ponds with high forest cover. Usually hatchlings and juveniles occupy shallow waters while adults move to deeper waters. / A correlation between the species’ critical thermal maximum and the habitat and geographic distribution hasbeen found (Ernst and Lovich 2009).,However,data about the species’ critical thermal maximum vary across the range (with 42.2°C being the highest recorded). Additionally,seasonal variations in resistance to temperature extremes are expected because of several relevant physiologicaland behavioural adaptations (Ernst and Lovich 2009).