PROJECT DESCRIPTION
BACKGROUND
The American bullfrog (Lithobates catesbeianus) and the African clawed frog (Xenopus laevis) are two invasive amphibian species that have been introduced to France, elsewhere in Europe and to other continents. They are a major threat for wetlands because of their disruptive impact on autochtonous communities (competition, predation, transmission of pathogens) and their strong colonisation capacity (high productivity and high dispersal). In France, the American bullfrog can be found in Gironde, Bassin d’Arcachon and Dordogne (Aquitaine), and Sologne (Centre), while the African clawed frog is present in a single area straddling two departments, Deux-Sèvres and Maine-et-Loire. Some populations are monitored and controlled, but there is no coordination at national level and insufficient sharing of resources and know-how. Furthermore, there is no methodology for identifying the appropriate control strategy for each species. The American bullfrog is listed as an Invasive Alien Species of Union Concern.
OBJECTIVES
The LIFE CROAA project aimed to completely eradicate the American bullfrog from 29 sites in Sologne and eight sites in Gironde and to significantly reduce the population of this invasive alien species (IAS) in Dordogne as a precursor to total eradication post-LIFE. At Bassin d’Arcachon, where the number of colonised sites is unknown, the project planned to prevent the American bullfrog population expanding. It also aimed to limit the expansion of the African clawed frog along dispersal corridors. Other specific project objectives were as follows:
- To develop a methodology for selecting control strategies for invasive populations of amphibians when the size of the colonised area impedes eradication (e.g. African clawed frog in Deux-Sèvres/Maine-et-Loire and American bullfrog in Gironde);
- To prevent novel introductions by identifying major pathways for alien amphibians and by raising awareness among stakeholders involved in the trade and exchange of animals; and
- To create an early detection and assessment system for the introduction of alien amphibians thanks to a network of local stakeholders (local population, authorities, pet shops, laboratories using alien species and amateur enthusiasts), the development of a mapping tool and the expertise of IAS managers.
The project actions targeting IAS would contribute to the EU Biodiversity Strategy to 2020 and the implementation of EU Regulation on IAS. The project team aimed to attend pet trade shows and provide training to those responsible for ensuring compliance with agreements on alien species. The aim was to assist the French government in strengthening and implementing EU regulation.
RESULTS
The LIFE CROAA project updated the distribution maps of the two target invasive amphibian species, the American bullfrog (Lithobates catesbeianus) and the African clawed frog (Xenopus laevis), increasing also knowledge of their biology and ecology, including their dissemination and adaptation capacity.
The project team also produced connectivity maps to assess the species’ dissemination potential in relation to the land cover. The team furthermore proposed key actions and a strategy for managing the invasive amphibian species that cannot be eradicated.
The team also carried out impact assessments of the target species on wetland ecosystems, while applying innovative techniques for trapping the species in order to restore habits by increasing competition from local species. The American bullfrog populations in the Sologne, Dordogne and Arcachon areas are believed to have been eradicated by the project actions, although the team was not able to adequately confirm their success.
Communication and awareness-raising activities targeted the general public, especially young people, amphibian and reptile owners and pet stores.
