Beyond the Shell: Reviewing the Ecological and Economic Impact of Trachemys scripta in Europe Over the Past 25 Years

ABSTRACT

The introduction of exotic species, alongside habitat degradation and global warming, is one of the most pressing issues in conservation ecology. Trachemys scripta is now widespread throughout Europe after decades of pet trade and releases and is often considered a threat to native freshwater turtles. This assumption led to the implementation of significant management efforts across Europe. However, understanding the true impact of T. scripta on the invaded habitats remains difficult to assess due to context dependence and limited empirical evidence. For this reason, we conducted a critical review of scientific literature examining the interaction between T. scripta and European freshwater turtles, combined with an analysis of the management costs of T. scripta within EU funded LIFE projects and an assessment of expert perception. We identified 39 studies, whose relevance highly depended on the study context; nine demonstrated an effective negative impact of T. scripta on native European turtles. Cost analysis from 13 LIFE projects revealed a total cost of 2,509,134 €, with an average removal cost of 364 € per individual turtle. Expert responses highlighted the importance of field‐based evidence and public awareness in management strategies. Overall, our findings indicate that the impact of T. scripta is context‐dependent and often difficult to quantify, while management actions can be economically demanding. This review provides an objective synthesis of the ecological and economic impact of T. scripta in Europe, proposing targeted, context‐specific and cost‐effective management strategies, based on precautionary action and realistic assessments of impact and feasibility.