Conservation status of freshwater mussels in Europe: state of the art, perspectives and future challenges

Freshwater bivalves of the Unionoidea provide important ecosystem functions, yet many of their populations are in decline. In the present work, we comprehensively review the status of all of the currently described species in Europe, addressing their phylogenetic and taxonomic relations, their distribution and conservation status, as well as their habitat preferences and main threats in order to suggest prospective conservation action. Information on the current status of Unionoids in Europe is very unevenly distributed with rather detailed information available for flagship species such as the freshwater pearl mussel (Margaritifera margaritifera) and little or no information available on the other species. Similarly, in certain regions such as British Isles, the Iberian Peninsula and central Europe, information is more consistent than in other part of Europe. In order to make conservation more effective in the future, we suggest a more standardized international approach to surveying European freshwater bivalves that need to encompass more ecological and genetic data.