Spatial priorities for freshwater biodiversity conservation in light of catchment protection and connectivity in Europe

RESEARCH ARTICLE Spatial priorities for freshwater biodiversity conservation in light of catchment protection and connectivity in Europe Ma´rton SzabolcsID1, Felı´cia Kapusi1, Savrina Carrizo2, Danijela Markovic3, Jo¨ rg Freyhof4, Nu´ ria Cid5, Ana Cristina Cardoso6, Mathias Scholz7, Hans D. Kasperidus7, William R. T. Darwall2, Szabolcs Lengyel1* 1 ELKH, Centre for Ecological Research, Institute of Aquatic Ecology, Department of Tisza Research, Debrecen, Hungary, 2 International Union for the Conservation of Nature, Global Species Programme, Freshwater Biodiversity Unit, Cambridge, United Kingdom, 3 Osnabru¨ck University of Applied Sciences, Osnabru¨ ck, Germany, 4 German Center for Integrative Biodiversity Research (iDiv), Leipzig, Germany, 5 University of Barcelona, Faculty of Biology, Department of Ecology, Barcelona, Spain, 6 European Commission, Joint Research Centre, Institute for Environment and Sustainability, Water Resources Unit, Ispra, Italy, 7 UFZ − Helmholtz Centre for Environmental Research, Department of Conservation Biology, Leipzig, Germany * lengyel.szabolcs@ecolres.hu Abstract Freshwater ecosystems host disproportionately high numbers of species relative to their sur- face area yet are poorly protected globally. We used data on the distribution of 1631 species of aquatic plant, mollusc, odonate and fish in 18,816 river and lake catchments in Europe to establish spatial conservation priorities based on the occurrence of threatened, range- restricted and endemic species using the Marxan systematic conservation planning tool. We

found that priorities were highest for rivers and ancient lakes in S Europe, large rivers and lakes in E and N Europe, smaller lakes in NW Europe and karst/limestone areas in the Bal- kans, S France and central Europe. The a priori inclusion of well-protected catchments resulted in geographically more balanced priorities and better coverage of threatened (criti- cally endangered, endangered and vulnerable) species. The a priori exclusion of well-pro- tected catchments showed that priority areas that need further conservation interventions are in S and E Europe. We developed three ways to evaluate the correspondence between con- servation priority and current protection by assessing whether a cathment has more (or less) priority given its protection level relative to all other catchments. Each method found that pri- ority relative to protection was high in S and E Europe and generally low in NW Europe. The inclusion of hydrological connectivity had little influence on these patterns but decreased the coverage of threatened species, indicating a trade-off between connectivity and conservation of threatened species. Our results suggest that catchments in S and E Europe need urgent conservation attention (protected areas, restoration, management, species protection) in the face of imminent threats such as river regulation, dam construction, hydropower develop- ment and climate change. Our study presents continental-scale conservation priorities for freshwater ecosystems in ecologically meaningful planning units and will thus be important in

freshwater biodiversity conservation policy and practice, and water management in Europe. PLOS ONE PLOS ONE | https://doi.org/10.1371/journal.pone.0267801 May 17, 2022 1 / 15 a1111111111 a1111111111 a1111111111 a1111111111 a1111111111 OPEN ACCESS Citation: Szabolcs M, Kapusi F, Carrizo S, Markovic D, Freyhof J, Cid N, et al. (2022) Spatial priorities for freshwater biodiversity conservation in light of catchment protection and connectivity in Europe. PLoS ONE 17(5): e0267801. https://doi.org/ 10.1371/journal.pone.0267801 Editor: Charles William Martin, University of Florida, UNITED STATES Received: August 24, 2021 Accepted: April 14, 2022 Published: May 17, 2022 Copyright: © 2022 Szabolcs et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data Availability Statement: The data underlying the results presented in the study are available from http://project.freshwaterbiodiversity.eu/ and https://www.hydrosheds.org/. Funding: This study was funded by the ‘BioFresh’ project [FP7-ENV-2008, contract no. 226874]. FK, MS and SL were also supported by three grants from the National Research, Development and Innovation Office of Hungary [K106133, K134391, GINOP 2.3.3-15-2016-00019], and MS was supported by a Young Researcher Fellowship from