Combining a cumulative risk index and species distribution data to identify priority areas for marine biodiversity conservation in the Black Sea

The Black Sea remains one of the most fragile marine systems globally. The six countries that share the coastline of this semi-enclosed sea have declared, through the Convention on Biological Diversity and regional conventions, their intention to conserve biodiversity and increase the coverage of the protected areas. However, currently only a small proportion of the marine area is under protection. Here, we spatially delineated priority conservation sites that could ensure species protection under the impact of different threats. We developed a cumulative risk index, incorporating anthropogenic pressures related to pollution and fisheries. We then combined this information with distribution data of marine species to apply a systematic conservation planning approach. We identified eleven key areas that cover 10% of the Black Sea, the protection of which could attain realistic conservation targets. These sites are mainly located in neritic and coastal habitats, which also host a number of species that avoid the anoxic part of the ocean basin. The management and efficient protection of these key areas require international collaboration, representing the only way to alleviate the severe degradation of this sensitive, but valuable, marine system.