Search

Sur les neuf espèces d'écrevisses présentes en France, six sont des espèces introduites dont les conséquences sur l’environnement créent de profonds déséquilibres biologiques. Dans le département des Vosges, des actions spécifiques sont expérimentées, notamment auprès des propriétaires d’étangs pour tenter de lutter contre l’expansion des écrevisses introduites et ainsi préserver les dernières populations d’écrevisses natives.Since the end of the XIXth century, the distribution of crayfish in France has gone through deep changes, and the introduction of allochtonous crayfish, essentially from the North American continent, has forever changed the French and European crayfish landscape.The four surveys organised in France by ONEMA since 1977 allow following the evolution of the different species of crayfish present on the national territory, showing each time the large expansion of the exotic species and the recess of the native species.The situation of our three native species must now be considered as alarming.Two of these species, Austropotamobius torrentium and Astacus astacus, are close to extinction, and the third one, Austropotamobius pallipes, can now be found on the upmost parts of the watersheds, confined in areas and under the pressure of the exotic species which are still making their way further up.Pacifastacus leniusculus and Procamabrus clarkii are showing the strongest geographical expansion. Everywhere they appear to be very strong competitors, more aggressive, resistant to pathologies, able to colonize varied environments. They are indeed colonizing new departments, new watersheds, and thus eliminating native species.The rhythm of the illegal introductions seems to accelerate because new species, native of the American continent, were recently discovered: Orconectes juvenilis in the department of the Doubs and Orconectes immunis in the departement of the Bas-Rhin.In terms of management of these species, the actions are rather rare at the national level. However in the department of Vosges, specific actions are experimented, in particular with the owners of ponds to try to fight against the expansion of the introduced crawfishes and so to protect the last populations of native crawfishes.

Freshwater crayfish are amongst the largest macroinvertebrates and play a keystone role in the ecosystems they occupy. Understanding the global distribution of these animals is often hindered due to a paucity of distributional data. Additionally, non-native crayfish introductions are becoming more frequent, which can cause severe environmental and economic impacts. Management decisions related to crayfish and their habitats require accurate, up-to-date distribution data and mapping tools. Such data are currently patchily distributed with limited accessibility and are rarely up-to-date. To address these challenges, we developed a versatile e-portal to host distributional data of freshwater crayfish and their pathogens (using Aphanomyces astaci, the causative agent of the crayfish plague, as the most prominent example). Populated with expert data and operating in near real-time, World of Crayfish™ is a living, publicly available database providing worldwide distributional data sourced by experts in the field. The database offers open access to the data through specialized standard geospatial services (Web Map Service, Web Feature Service) enabling users to view, embed, and download customizable outputs for various applications. The platform is designed to support technical enhancements in the future, with the potential to eventually incorporate various additional features. This tool serves as a step forward towards a modern era of conservation planning and management of freshwater biodiversity. [ABSTRACT FROM AUTHOR]

The white‐clawed crayfish (Austropotamobius pallipes) is globally endangered due to the impacts of habitat modification and fragmentation, water pollution, climate change, and invasive species, particularly the signal crayfish (Pacifastacus leniusculus). These pressures have caused the decline of A. pallipes populations in Europe, demonstrating the importance of predicting the species' potential distribution under current and future conditions. Focusing on the watercourses of mainland France, we aimed to identify suitable areas for A. pallipes to guide the conservation of current populations and future introduction actions or protection measures.We applied ecological niche modelling to model the potential distribution of both A. pallipes and P. leniusculus and identified locations suitable for A. pallipes only. We also assessed the potential distribution of the species under two representative concentration pathway (RCP) scenarios: RCP 2.6 and RCP 8.5, respectively describing low‐warming and high‐warming conditions.We found that A. pallipes and P. leniusculus exploit equivalent niches in France. Despite this, under current conditions, about 5% of the study area simultaneously records a high suitability for A. pallipes and a low suitability for P. leniusculus and is therefore of significant conservation interest. This percentage remains relatively stable under RCP 2.6 for 2050 and 2100, but decreases to 2% under RCP 8.5 for 2100.Ecological niche modelling can supply crucial guidance for conservation actions aimed at protecting endangered species at a national scale by identifying sites most suitable for protection and sites where climate change and invasive species constitute a threat. [ABSTRACT FROM AUTHOR]