Towards achieving a twenty-fold increase in the coverage of freshwater species distributions within protected areas in Europe.

Freshwater ecosystems are threatened worldwide, with 1/3 of freshwater species being under extinction risk. Yet, systematic conservation planning has received little attention as a means to prioritize freshwater conservation areas. Here, we develop a comprehensive approach to spatially delineate key areas for freshwater conservation across Europe, considering directed-connectivity, climate change and human-related disturbances. We assess the adequacy of the current reserve network in protecting European freshwater ecosystems and provide guidelines for expansion. We conducted 13 prioritization scenarios for 18,300 sub-basins across Europe, accounting for the distribution of 1,668 freshwater species. Connectivity properties, metrics of climatic stability and human induced pressures were incorporated into the spatial prioritization framework. We highlight the critical importance of specific regions in Central and Southern Europe, the Mediterranean Basin, and parts of the Balkan Peninsula for future freshwater conservation efforts. However, our analysis also reveals the complete inadequacy of the current reserve network, as protected sub-basins only cover 4 % of the study area and encompass on average only 3 % of freshwater species distributions. In contrast, expanding current reserves to cover the top 17 % of high priority areas across Europe could substantially improve the overall coverage of species distributions, reaching an average of 61.5 % for all freshwater species and even exceeding 93.1 % for species of conservation interest (critically endangered, endangered and vulnerable species). The priority freshwater conservation network derived from the analysis provides specific spatial recommendations to help achieve conservation goals if the current reserve network is appropriately expanded. • Freshwater species are at risk worldwide and conservation planning is overlooked. • A new comprehensive approach prioritizes key areas for European freshwaters. • Critical regions for conservation exist in Central Europe and the Mediterranean. • Current reserves are inadequate covering only 4 % of Europe's freshwater ecosystems. • Expanding reserves can result in a 20-fold increase in species coverage within PAs. [ABSTRACT FROM AUTHOR]