One Against All: The Fight of the European Pond Turtle Against the Invasion of Exotic Turtles
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Since World War II, the legal and illegal trade of freshwater turtles has significantly increased, but many owners are unprepared to care for animals that can live for decades. Unfortunately, many of these turtles are released into the wild, causing serious consequences for local ecosystems.
According to the IPBES (Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services), biological invasions by exotic species are one of the leading causes of native species extinction. These invasive species compete for space and resources, transmit pathogens and parasites, and can even hybridize with local species. The European pond turtle (Emys orbicularis) is one of the victims of this invasion in Europe, where it faces competition from at least seven exotic species, such as the red-eared slider (Trachemys scripta).
A recent study analyzed how the distribution of these species may change due to climate change. Researchers used a species distribution model (SDM), based on 19 climatic and geographic variables, to understand the future dynamics between E. orbicularis and exotic turtles. These exotic species were chosen as they represent a complete list of invasive turtles found in the range of the European pond turtle, including its northern and southern borders in Eastern Europe, such as Latvia and Ukraine.
The results show that E. orbicularis is relatively tolerant to future temperature changes, with the potential to expand its range northeastward, even into regions around the Baltic Sea and southern Sweden. However, this expansion may be hindered by competition from invasive species. By 2050, T. scripta, already the most common exotic turtle in Europe, is expected to expand its range into Ukraine, Belarus, and the Baltic States, further pressuring E. orbicularis.
Other exotic species, such as Graptemys pseudogeographica and the Middle Eastern turtles Mauremys caspica and Mauremys rivulata, are also predicted to expand. M. rivulata in particular could triple its range, finding new habitats in Mediterranean countries and Southeastern Europe. However, for these species, current southern habitats may shrink significantly due to climate change.
Despite E. orbicularis currently covering 37% of Europe’s total surface area, with a predicted expansion toward the northeast, this growth could be threatened by competition with alien species. Climate change, combined with the popularity of exotic turtles as pets, may accelerate this process, favoring the spread of these invasive species.
What can we do? It is crucial for potential buyers of exotic animals to be aware of the ecological consequences. Purchasing exotic turtles should be done with great care, avoiding their release into natural environments. Every action counts in preserving ecological balance and protecting native species like the European pond turtle.
See you soon and Good Science!
article: Nekrasova, Oksana, et al. "Present and future distribution of the European pond turtle versus seven exotic freshwater turtles, with a focus on Eastern Europe." Scientific Reports 14.1 (2024): 21149.
picture: https://www.parchilazio.it/schede-28471-la_nostra_testuggine_palustre_emys_orbicularis
