Revision of the EUNIS inland surface water habitat group: finalisation of level 3 and outlook to level 4

The EUNIS habitat classification is a comprehensive pan-European system for habitat identification. This classification is hierarchical and covers all types of habitats in Europe. It was developed by EEA and ETC/BD and its predecessors in 1995 and revised since 2011. In first instance this revision was performed for terrestrial and marine habitats, while the revision of the inland water habitat classification only started in 2016 and was elaborated since. A team consisting of EEA, ETC/BD and ETC/ICM had the lead in the whole process of the revision of the inland water habitats. The process started with a scoping study followed by two expert workshops, an EIONET consultation and an EIONET webinar, in which a large number of countries and a wide audience of experts were engaged at appropriate intervals during the revision process. From the start of the process it was decided that an alignment with the existing broad types derived from the Water Framework Directive intercalibration types would be the best way forward supplemented with smaller and rare aquatic habitats which considerably contribute to biodiversity in Europe. The final list of EUNIS level 3 running and standing waters includes 22 habitats for standing waters and 26 habitats for running waters. Although a floristic approach was considered appropriate for the revision of EUNIS terrestrial habitats, a different approach was needed for EUNIS inland waters. These habitats are characterized by more groups of organisms. A methodology and identification of the sources for extracting biological information to be linked to the level 3 standing and running waters were developed. This extraction of the biological information is ongoing and needs further elaboration in 2023.