Environmental objectives and aquatic environment limits for stone crayfish
The stone crayfish (Austropotamobius torrentium) is a critically endangered species listed on the Red List of Invertebrates of the Czech Repub-lic. It is protected under Decree No. 395/1992 Coll. and designated as a priority species according to Council Directive 92/43/EEC on the conservation of natural habitats, wild fauna, and flora. It is generally assumed that stone crayfish requires water quality that meets at least the emission limits for salmonid waters as defined by Government Regulation No. 71/2003 Coll., as amended, and also by Government Regula-tion No. 401/2015 Coll., as amended. Stable and abundant populations, however, require stricter environmental objectives, both in terms of limit values and the range of monitored parameters. To establish these objectives, 14 sites were selected. These sites are either unaffected or only slightly influenced by human activities, with confirmed current occurrence of stone crayfish or historical presence where disappearance was probably due to crayfish plague.