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Map with new and previously published localities of Trachemys scripta in different biogeographical regions of Croatia. Slika 2. Zemljevid z novimi in že objavljenimi lokalitetami vrste Trachemys scripta v različnih biogeografskih regijah Hrvaške.
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The pond slider Trachemy scripta was one of the most commonly exported turtles until the last decade and often released into the wild outside its native range. It was introduced to Europe, Africa, South America and Asia and included on the EU list of 100 World's Worst Invasive Alien Species and the List of invasive alien species of Union concern. T...
Citations
... Not surprisingly, there are a few records of anthropogenic reptile introductions, such as Podarcis siculus in Albania, Montenegro, Greece, Turkey, France, the Iberian Peninsula, North Africa and some Mediterranean islands (Silva-Rocha et al., 2014;Mizsei et al., 2016;Gvozdenović and Iković, 2022). Likewise, Trachemys scripta was introduced in Serbia, Montenegro, Croatia, Bulgaria, Greece, and many other countries of the Balkan Peninsula (Urošević, 2014;Jelić and Jelić, 2015;Tzankov et al., 2015;Stȃnescu et al., 2017;Koren et al., 2018;Tzoras et al., 2018;Urošević et al., 2019;Kornilev et al., 2020;Panjković et al., 2021;Ljubisavljević, 2022), but also amphibians such as Xenopus laevis and Lithobates catesbeianus (Panjković et al., 2021). ...
Kotschy's gecko, Mediodactylus kotschyi, is native to the Eastern part of the Mediterranean Basin and a successful colonizer, with an extensive distribution across the Balkans and outside its native range. In Serbia, it was presumed native in Prizren (Kosovo and Metohija province) and introduced across the remaining territory. To explore the origin of Serbian Kotschy's gecko, we collected specimens from most of the Serbian populations where the species was recorded and assessed their phylogenetic relationships based on three mtDNA markers (COI, cytb, 16S rRNA) under Maximum Likelihood (ML) and Bayesian Inference (BI) approaches. First, our results support that the specimens found in Serbia belong to M. kotschyi. Second, all populations except Prizren belong to the subspecies M. kotschyi skopjensis. Furthermore, the Italian populations are sister to the specimens from Prizren, suggesting a Balkan origin for these populations, which settled in Apulia likely through ancient human-mediated dispersion. The small genetic differentiation found suggests that Kotschy's gecko rapidly colonized the Central Balkans, originating from Northern Greece and North Macedonia. The results also suggest a story of multiple, complex (most likely) human-mediated introductions. However, further studies should be conducted to properly elucidate the colonization pathways, and to truly disentangle the potential fast natural range expansion from an anthropogenic dispersion of this gecko species.
... Databases were created based on the available points of registration of the target species using original records as well as data published in literature [16][17][18]29,34,[48][49][50][51][52][53][54][55][56][57] UkrBin, GBIF.org, 2022. Records of these exotic turtle species in Europe are not numerous, uneven and do not reflect neither the ecological niche nor their natural habitat. ...
Freshwater turtles are often used as terrarium pets, especially juveniles of exotic species. At the adult stage they are often released by their owners into the wild despite their high invasion potential. In Europe these thermophilic potentially invasive alien species occupy the habitats of the native European pond turtle Emys orbicularis (Linnaeus, 1758), with new records from the wild being made specifically in Eastern Europe (Latvia and Ukraine) during recent decades. Assessing the potential of alien freshwater turtles to establish in new territories is of great concern for preventing invasion risks while preserving native biodiversity in the present context of climate change. We explored this issue by identifying the present and future (by 2050) suitable habitats of the European pond turtle and several potentially invasive alien species of freshwater turtle already settled in Europe, using a geographic information system (GIS) modelling approach based on datasets from CliMond for climate, Near-global environmental information (NGEI) for freshwater ecosystems (EarthEnv) and Maxent modelling using open-access databases, data from the literature and original field data. Modelling was performed for seven species of alien freshwater turtles occurring from the extreme northern to southern borders of the European range of E. orbicularis: the pond slider Trachemys scripta (Thunberg and Schoepff, 1792), the river cooter Pseudemys concinna (Le Conte, 1830), the Florida red-bellied cooter Pseudemys nelsoni (Carr, 1938), the false map turtle Graptemys pseudogeographica (Gray, 1831), the Chinese softshell turtle Pelodiscus sinensis (Wiegmann, 1835), the Caspian turtle Mauremys caspica (Gmelin, 1774) and the Balkan terrapin Mauremys rivulata (Valenciennes, 1833). In Ukraine, the most Eastern limit of E. orbicularis distribution, were previously reported northern American originated T. scripta, M. rivulata, M. caspica, whereas in Latvia, Emys’ most northern limit, were additionally reported P. concinna, P. nelsoni, G. pseudogeographica and Asia originated P. sinensis. The resulting Species Distribution Models (SDM) were of excellent performance (AUC > 0.8). Of these alien species, the most potentially successful in terms of range expansion throughout Europe were T. scripta (34.3% of potential range expansion), G. pseudogeographica (24.1%), and M. caspica (8.9%) and M. rivulata (4.3%) mainly in Eastern Europe, especially in the south of Ukraine (Odesa, Kherson, Zaporizhzhia regions, and Crimean Peninsula). Correlation between the built SDMs for the native E. orbicularis and the invasive alien T. scripta was reliably high, confirming the highly likely competition between these two species in places they cooccur. Moreover, a Multiple Regression Analysis revealed that by 2050, in most of Europe (from the western countries to Ukraine), the territory overlap between E. orbicularis and potentially invasive alien species of freshwater turtles will increase by 1.2 times, confirming higher competition in the future. Importantly, by 2050, Eastern Europe and Ukraine are predicted to be the areas with most suitable habitats for the European pond turtle yet with most limited overlap with the invasive alien species. We conclude that Eastern Europe and Ukraine are the most relevant priority conservation areas for the European pond turtle where it is now necessary to take protective measures to ensure safe habitat for this native species on the long-term.
... Therefore, we use the term "sliders" to highlight the fact that our study refers to T. scripta without considering subspecies and acknowledges the potential presence of hybrids between them, while also differentiating them from the native pond terrapin. The reproduction of T. scripta in the wild has been reported in several European countries, including Austria (Kleewein 2014), Croatia (Koren et al. 2018), France (Cadi et al. 2004), Germany (Schradin 2020;Tietz et al. 2023), Italy (Ferri and Soccini 2003;Ficetola et al. 2003;Sperone et al. 2010;Crescente et al. 2014), Portugal (Martins et al. 2018), Serbia (Đorđević and Anđelković 2015), Slovenia (Vamberger et al. 2012;Standfuss et al. 2016), Spain (Silvestre et al. 1997;De Roa and Roig 1998;Bartolero and Canício 2000;Capalleras and Carretero 2000;Pleguezuelos 2002;Perez-Santigosa et al. 2008;Costa et al. 2016), and Turkiye (Çiçek and Ayaz 2015). While it was commonly assumed that T. scripta also breeds in Romania, given that juveniles were occasionally observed in the wild (Iftime and Iftime 2021), there were no documented reports of successful reproduction, and no data on nesting sites, egg-laying timing, or hatching rates. ...
The pond slider (Trachemys scripta) is a major invasive species in freshwater habitats across the world. For decades, the main cause of individuals’ occurrences in the wild was the illegal release of pet animals. Recently, as an important component of their management, there has been an increasing focus on their ability to successfully reproduce in the invaded regions. In Romania, the species is reported as widespread in urban wetland environments within major cities, but information about its nesting and potential breeding remains scarce or anecdotal. We surveyed a large population of pond sliders in an artificial urban wetland site in Constanţa, SE Romania, and described their nesting ecology and reproductive output. Although eggs from several nests failed to hatch or were predated, potentially limiting their reproductive success, sliders were found to breed successfully at this site, with 18.6% viable hatchlings recorded. Our study could serve as a baseline for additional targeted surveys and to inform decision-making for successfully managing this invasive species. Although the importation, trading, and breeding of this species are prohibited by EU legislation, active and effective management is now required to address the successful reproduction and further potential spread of T. scripta.
... The pond slider specimens are released in nature by irresponsible owners and up until now the species has become distributed in the wild in almost all European countries, where they also breed successfully (e.g. Vamberger et al. 2012;Standfuss et al. 2015;Speybroeck et al. 2016;Stănescu et al. 2017;Koren et al. 2018;Urošević et al. 2019;Kornilev et al. 2020). As the European Union banned import and trade of T. s. elegans in 1997, other two subspecies have become substitute species in the pet markets (Urošević et al. 2019). ...
... This is related to the fact that more systematic surveys have been done in the coastal area, which was not the case as far as other parts of the country are concerned. The records made in Croatia by Koren et al. (2018) were almost equal in the Mediterranean and Continental regions, without any findings in the Alpine region, while Urošević et al. (2019) reported that most pond slider findings in Serbia were in habitats below 100 m a.s.l. In Bulgaria, the pond slider's vertical distribution ranged from sea level up to 956 m, with most findings below 250 m a.s.l., and just three findings above 600 m a.s.l. ...
... Pond slider findings in Montenegro are from different aquatic ecosystems, including lakes, ponds, rivers, and streams close to urban areas. Those results are in agreement with data from other Balkan countries (Jelić & Jelić 2015;Koren et al. 2018;Urošević et al. 2019;Kornilev et al. 2020), which unequivocally confirms the fact that specimens are released by owners in urban aquatic ecosystems as unwanted pets. Our results indicated that among most localities one to five specimens were observed, while at the pond at Mrke-Blizna, numerous specimens exist. ...
The Pond Slider is one of the 100 world's most invasive alien species, widely introduced to Europe and all over the world. The number of specimens recorded in nature is increasing in the Balkans, including Montenegro. In this paper, we present literature and new findings of pond sliders in this country. So far, 10 known localities have been identified, most of them in the Mediterranean biogeographical region. Records are from different aquatic ecosystems, including lakes, ponds, rivers and streams. Locality Mrke-Blizna is identified as a potential breeding site, as numerous specimens are present here including hatchlings.
... For example, despite a great number of occurrence records in Europe, the establishment of self-sustained populations of this terrapin has been proved only for southern regions of Europe in Spain, Italy and southern France Perez-Santigosa et al. 2008;Ficetola et al. 2009;Crescente et al. 2014). On the other hand, specialists report successful reproduction in a larger number of localities and do not exclude the possibility of established populations in Portugal, Greece, Croatia, Slovenia, and Serbia, in locations where a similar Mediterranean climate is prevalent (Bruekers et al. 2006;Đorđević and Anđelković 2015;Standfuss et al. 2016;Koren et al. 2018;Martins et al. 2018;Tzoras et al. 2018;Urošević et al. 2019;our data). Of course, some observed groups of terrapin may be at different stages of invasion debt (Essl et al. 2011), with potential establishment of populations in the future, after the accumulation of humanreleased individuals of reproductive age and/or due to future climate alterations. ...
The North American terrapin, the red-eared slider, has globally recognized invasive status. We built a new extensive database using our own original and literature data on the ecology of this reptile, representing information on 1477 water bodies throughout Eurasia over the last 50 years. The analysis reveals regions of
earliest introductions and long-term spatio-temporal dynamics of the expansion covering now 68 Eurasian countries, including eight countries reported here for the first time. We established also long-term trends in terms of numbers of terrapins per aquatic site, habitat occupation, and reproduction success. Our investigation has revealed differences in the ecology of the red-eared slider in different parts of Eurasia. The most prominent expression of diverse signs of invasion success (higher portion of inhabited natural water bodies, higher number of individuals per water body, successful overwintering, occurrence of juvenile individuals, successful reproduction, and establishment of populations) are typical for Europe, West Asia
and East Asia and tend to be restricted to coastal regions and islands. Reproduction records coincide well with the predicted potential range based on climatic requirements but records of successful wintering have a wider distribution. This invader provides an excellent and possibly unique (among animals)
example of wide alien distribution, without the establishment of reproducing populations, but through the recruitment of new individuals to rising pseudo populations due to additional releases. Therefore, alongside the potential reproduction range, a cost-effective strategy for population control must take in
account the geographical area of successful wintering
... In the eastern part of the Mediterranean, the species is also present in many countries, such as Turkey [47], Jordan [48], Israel [49,50], and Cyprus [51]. In the Balkan peninsula (Croatia, Montenegro, Serbia, Romania, and Bulgaria) wild populations of the common slider have also been found [52][53][54][55][56][57]. ...
Island wetlands are considered crucial to biodiversity due to their unique ecological, biogeographical, and socioeconomic dynamics. However, these habitat types are particularly vulnerable to invasion; invasive species can cause severe ecological, evolutionary, and epidemiological impacts on native species. One of the most important invasive species, the common slider Trachemys scripta, an opportunistic inhabitant of freshwater habitats, has been released in multiple localities across Greece in recent years, and has expanded its range through random and unintentional releases in the Aegean islands. Since its first documented record on the island of Crete in 1998, the species has been observed on six more islands. Here, we report, for the first time, two subspecies of the common slider (T. scripta scripta and T. scripta elegans) on the wetlands of the island of Lesvos. We discuss the potential threats to native terrapins and we examine whether the introduction of this invasive species has affected native terrapins by monitoring their populations for 12 consecutive years (2010–2022). We found the common slider in 3 out of 110 wetlands surveyed. At one site, we document the presence of invasive terrapins belonging to two different subspecies. In all surveyed wetlands, we found stable populations of the two native freshwater terrapins, Mauremys rivulata and Emys orbicularis, with the first species found in much larger populations than the second. Despite these reassuring findings, the presence of this introduced species on the island of Lesvos raises serious concerns regarding its negative effects on the local terrapin populations. We propose that systematic and thorough monitoring of insular wetlands, as in the case of Lesvos, should be adopted on other islands as well, with priority on those where the common slider has been recorded
... Also, the sale of these turtles has continued with individuals being produced in EU member states since 2016 when the EU Regulation 1143/214 on invasive alien species was approved (European Parliament, Council of the European Union, 2014). Up to now, occurrences of nominotypical subspecies are reported in many European countries including the Balkans (e.g., Krofel et al., 2009;Urošević, 2014;Jelić and Jelić, 2015;Tzankov et al., 2015;Koren et al., 2018;Urošević et al., 2019). In Montenegro, only one published record is available for T. s. elegans (Lužnik et al., 2006; also reviewed in Žagar et al., 2013), while for T. s. scripta no record existed until this note. ...
... It appeared in Ukrainian freshwater bodies as a result of the illegal pet trade and subsequent releases, both intentional and unintentional [26]. With a currently expanding distribution area to the north as a result of global climate change, as well as it being released by local people, T. scripta is already confirmed to be producing viable clutches in some European countries, e.g., Croatia [27], indicating a potential serious negative impact on local biota. Nyctereutes procyonoides occupies a wide range of territories in Polissia (forested biogeographical region which starts from the farthest edge of central Europe and encompasses eastern Europe, including eastern Poland, the Belarus-Ukraine border and western Russia) and the forest-steppe zone, preferring wet meadows with swampy lowlands, overgrown river floodplains and riverine forests with dense undergrowth; moreover, Nyctereutes procyonoides is unpretentious when choosing places to inhabit. ...
In order to use an integrated approach for studying the influence of risk factors on the distribution of the native turtle species E. orbicularis and accompanying invasive species (T. scripta and N. procyonoides) in the northeast of their range, we used GIS modelling and a database (GAEZ, human footprint, CliMond) of 55 preselected variables, which represent a system of bioclimatic and anthropogenic factors. The main variables that influenced the results were factors related to temperature. There was a high correlation (r = 0.6) between the species distribution model's habitat suitability for E. orbicularis and the corresponding "human footprint" values within the European part of the species' natural range. Its unpretentiousness towards anthropogenic factors would likely help the further expansion of its range in eastern Europe, because the areas with the highest habitat suitability (r > 0.7) were projected to increase 3.3-fold. When comparing the E. orbicularis model to those obtained for N. procyonoides and T. scripta, we concluded that N. procyonoides could be dangerous because it occupies similar habitats (the degree of correlation is reasonably high in the north of their range (r = 0.5) in Latvia). An expansion of the range of Trachemys scripta is also possible in the future within the northern territories. Therefore, when developing the turtles' protection algorithms, it is also necessary to take into account the influence of invasive species.
... Reproduction of released T. scripta has been reported in southern Europe (Cadi et al., 2004;Perez-Santigosa, díaz-Paniagua & Hidalgo-Vila, 2008;Sperone et al., 2010;Sancho & Lacomba, 2016;Foglini & Salvi, 2017), but also in a part of Croatia with a continental climate (Koren et al., 2018), as well as in central Europe in Slovenia (Standfuss et al., 2016). The regular reproduction of T. scripta reported here for Germany adds to previous records of successful reproduction in temperate climates. ...
... In light of the facts uncovered by the current study that population size is not decreasing, there is no indication of high mortality and successful reproduction occurs more regularly than previously believed, the management plan in Germany should be reconsidered. The results presented here add to several other studies indicating that T. scripta has the potential to become invasive in western, middle and central Europe (Mačát & Jablonski, 2016;Standfuss et al., 2016;Koren et al., 2018). Thus, action plans to avoid an invasion might not only have to be changed for Germany, but for many other European countries. ...
The European Union categorises pond sliders (Trachemys scripta) as invasive species for which all member countries have to develop an action plan. To date it has been assumed that the climate in Germany is too cold for T. scripta to survive or reproduce. Data collected annually from 2016 to 2020 show that the population of exotic pond turtles in an oxbow lake (Althrein of Kehl, Germany) did not decrease but increased. In addition, the diversity of species released was found to be high, five other exotic species in addition to T. scripta were observed. The population of T. scripta in particular appears to be increasing, with no indication of high mortality due to cold winters and apparently regular successful reproduction (hatchlings observed in four out of five study years and caught in two years). The current action plan in Germany for T. scripta will have to change if potential negative impacts are to be avoided. Other west and central European countries might also have to modify their action plans accordingly.
... While Bringsøe (2001) suggested that the climate in Europe is not suitable for successful development of T. scripta eggs (cold winters in the north, hot dry summers in the south), by now the numerous reports of confirmed reproduction (Koren et al. 2018) and the observations presented in our work provide evidence to the contrary. ...
Since its appearance in pet stores in Bulgaria in the 1990s, the pond slider Trachemys scripta has been released at multiple localities across the country, but this process has been subject to limited scientific attention. Here, we update the distribution of this invasive alien species by adding 17 new squares to the previously published 30 of the 10×10 UTM grid. All three subspecies are present in the country, including a subadult T. s. troostii observed in 2018 at a single locality in Rupite Area, southwestern Bulgaria. More importantly, we report observations of hatchlings of T. s. elegans from two consecutive years in Rupite Area and of two subadults at Velyov Vir (Ropotamo River, Black Sea coast), strongly suggesting successful breeding in the wild. Furthermore, we provide the first national ecological niche model for T. scripta, concluding that large potentially suitable areas exist throughout the country, especially at low altitudes. We discuss similarities in the climatic conditions between the native range and Bulgaria, further suggesting that the species could likely survive and potentially reproduce across the country.
