Chelonian challenge: three alien species from North America are moving their reproductive boundaries in Central Europe

Abstract

Biological invasions by alien species have substantial economic impacts and are a major driver of the ongoing decline and loss of biodiversity. Through humans, the North American pond slider (Trachemys scripta) has acquired a global distribution over the last decades and is currently listed among the worst invasive reptile species. However, in more recent times, other freshwater chelonian species have increasingly been recorded far outside their native distribution ranges as well, not only on the same continent but also on others. Despite that, the impact of alien chelonians on their respective new ecosystems remains unclear. The long-term effects and severity of impacts of alien populations mostly depend on whether they ultimately succeed in establishing themselves. This is not entirely resolved for chelonians in Central Europe. To answer that, we investigated wild populations of three non-native chelonian species from North America in Germany (Pseudemys concinna, Graptemys pseudogeographica and Trachemys scripta) applying population genetic approaches. We revealed the successful reproduction of all three species in Germany and provide the very first record for the reproduction of P. concinna and G. pseudogeographica in a temperate continental climate zone outside their native distribution. Based on our unambiguous evidence of natural reproduction, we call for dedicated studies to verify how widespread established populations are and to investigate the existing and potential impacts of all three species in a range of ecosystems along a climatic gradient. Such data is urgently needed to revise the current risk assessments of non-native chelonians, especially in Central European countries.

Effects of urbanisation, habitat characteristics, and management on garden pond biodiversity: a citizen science approach

“…Previous studies found that aquaria and garden ponds may act as sources of invasive species (Chucholl, 2013; Patoka et al, 2014; Soes et al, 2011; Van Den Neucker et al, 2017), e.g. the red-eared slider ( Trachemys scripta elegans ) (Tietz et al, 2023), water hyacinth ( Pontederia crassipes ) (Olden et al, 2021), signal crayfish ( Pacifastacus leniusculus ) (Chucholl et al, 2021). In this sense, without the indispensable knowledge and education about invasive species, garden pond owners and garden centers can pose a threat to native biodiversity.…”

Journal of Water and Land Development

“…The pond slider Trachemys scripta is regarded in the European Union as an invasive species (IAS) due to its reproductive success and establishment of viable populations not only in the Mediterranean region [STANDFUSS et al 2016] but also in more northern European countries like Germany [TIETZ et al 2022]. It is known, that in some parts of the invaded region, it negatively impacts the native European pond turtle [STANDFUSS et al 2016;JABLONSKI et al 2017], however, the impact on local communities and the ecosystem is still unknown.…”

“…These authors elucidated for the first time the invasive potential of the Trachemys populations in Slovenia and provided crucial knowledge for the conservation and management of the native European pond turtle. Recently, another study by TIETZ et al [2022] genetically confirmed the successful reproduction of the alien pond slider also in Germany.…”

Current Status of and Threats to Sicilian Turtles

“…However, lacking a proper assessment of the species on the island, its actual local distribution is partially unknown. Standfuss et al [64] and Tietz et al [81] genetically proved the invasive potential and the successful reproduction of T. scripta in Slovenia and Germany, respectively. Evidence of successful reproduction of the pond slider in the Italian peninsula was reviewed by Ficetola et al [76]; see also [82].…”