A spatially explicit approach to prioritize protection areas for endangered freshwater mussels

In spite of their conservation importance, only a fraction of lakes and streams globally – including their catchments – are currently covered by conservation areas. To identify conservation gaps, assessing the spatial distribution of biodiversity in relation to conservation areas is a promising approach. A gap‐analysis approach was used to evaluate the protection status of the habitats of two endangered freshwater mussel species,Margaritifera margaritifera(Linnaeus, 1758) andUnio crassus(Philipsson, 1788), in the Federal State of Bavaria, Germany. First, ecological niche models (ENMs) were developed for both mussel species based on presence‐only data in order to identify suitable habitats. Second, binary maps of suitable and unsuitable habitats for the species were used to compare different categories of currently protected areas in a gap analysis. The ENMs forM. margaritiferarevealed a spatially restricted distribution with good model performance, whereas the spatial distribution ofU. crassuswas wider and the model performance was weaker. ForM. margaritifera, a higher percentage of suitable habitat is already under some sort of protection, whereas forU. crassusonly half of the suitable habitats are under protection. The results suggest that suitable habitats of both species are not sufficiently protected. More effective conservation ofM. margaritiferaandU. crassusrequires separate management: increasing the respective protection categories of already protected habitats ofM. margaritiferaand incorporating an increased area of suitable habitats under legal protection forU. crassus.