The current biodiversity crisis is the result of many years of unsustainable use of nature. The area of wetlands in Europe has decreased by 90% in the last three centuries due to anthropogenic use. Wetlands are the reservoir for continental freshwater and are among the richest ecosystems in terms of biodiversity. Habitat loss is eroding biodiversity, recently estimated at € 450 billion per year for Europe only.
One way of overcoming such a biodiversity crisis is to restore habitats and reintroduce species. This is one of the cornerstones of modern conservation biology. In this context, thanks to a 4-year INTERREG grant (2009-2012), a 15 km2 area of the Upper Rhine at the German-French border (see the image bellow) has benefited from extensive work: on the one hand, the wetlands have been restored in order to create habitats for around 500 pond turtles (Emys orbicularis); on the other hand, the breeding of "pure" E. orbicularis orbicularis of the presumably autochthonous genetic line "IIa" for the area, in Mulhouse and Saint-Louis (France), and in Speyer (Germany) for reintroduction in Lauterbourg and Neuburg am Rhein, respectively.
The monitoring of environmental conditions and of pond turtle individuals and populations is endorsed by CNRS and Senckenberg thanks to common protocols. The goal of this long-term cross-border monitoring is to evaluate the success of the reintroduction based on survival, growth, distribution and reproduction and their socio-ecological impacts on the system.
Our first results of the monitoring, which has been carried out every year since 2012, show that the wetlands at Woerr in Lauterbourg have been efficiently restored. The invasive calico crayfish(Faxonius immunis) has been detected in some of these waters, which raises the question of a potential syntopic occurrence and the trophic connection between pond turtles and calico crayfish. Behavioral experiments with turtles and calico crayfish and additional genetic analyses of turtles' feces have proven that turtles do prey on calico crayfish.
The breeds have already produced > 500 individuals. So far 96 turtles have been released in Neuburg and 420 animals at Woerr in Lauterbourg. The animals released into the wild have already started to spread; in 2019, the first French animals were localized on the German side of the Woerr. The Neuburg turtles are already showing greater mobility due to their sexual maturity. The first landings in search of potential nesting sites have also been spotted and the first hatchlings from the wild were discovered in both Lauterbourg and Neuburg populations.
Since the animals are now sexually mature and begin to spread and reproduce, the continuation of our intensive monitoring of almost 10 years will aim at a reliable assessment of the long-term success and impacts of the reintroduction. In particular, knowledge about the development of the animals in the wild, the spatial use of the habitat and their successful reproduction require intensive field observations and state-of-the art approaches and technologies (e.g. environmental genomics, animal-borne data-loggers). In addition, the ecological approach is completed with a sociological approach that aims to assess the public perception and acceptance of such massive resettlement measures in order to provide integrative operational guidelines for local land managers (local councils, NGOs) but also for homologous projects aiming at reintroducing the European pond turtle throughout Europe.
