The native crayfish Austropotamobius pallipes complex in the Foreste Casentinesi National Park (Central Italy): conservation status and threats

The white-clawed crayfish Austropotamobius pallipes complex populations are declining in Italy, mainly due to habitat alteration, invasive alien species and pollution. This study assessed the conservation status and updated the distribution of A. pallipes complex in Foreste Casentinesi National Park (FCNP) (Tuscany and Emilia-Romagna, Central Italy) during three years of sampling (2021–2023). The abundance index Catch Per Unit Effort (CPUE) was used for comparing data among different sites and between the current and a previous sampling period (2012–2016). Overall, in the FCNP, the species experienced a decline in its populations over time, particularly severe in the Tuscan side while in the Emilia-Romagna sites a more stable situation was found. The main causes of this decline could be attributed to the invasive North American raccoon (Procyon lotor), whose distribution mainly overlaps with Tuscan crayfish populations, but also poaching episodes and the alteration of rainfall regime. Moreover, the presence of microsporidiosis and of individuals with blue colouration was reported. These findings emphasize the urgent need of coordinated actions for the conservations of A. pallipes complex including alien species management, habitat protection and long-term monitoring.