How well does NATURA 2000 protect threatened stone crayfish in Croatia?

The stone crayfish Austropotamobius torrentium (Schrank, 1803) is a threatened native European freshwater crayfish species for which Natura 2000 network represents the most important conservation effort at the European level. In Croatia, there are altogether 25 Natura 2000 sites defined specifically for this species. In the present study, we aimed to assess the effectiveness of Natura 2000 sites in preserving stone crayfish diversity through gap analysis, a GIS-based approach that overlays species distribution data on a map of designated Natura 2000 sites. Our results showed that the existing Natura 2000 network in Croatia encompasses most of the areas with a high diversity of A. torrentium; currently designated sites harbour 73.3% of recorded A. torrentium populations. Future conservation planning efforts, and possible expansion of Natura 2000, should be focused on newly discovered A. torrentium populations that present divergent evolutionary lineages.