Verifying a biotope classification using benthic communities – An analysis towards the implementation of the European Marine Strategy Framework Directive

•The HELCOM classification system (HUB) is tested for the south-western Baltic Sea.•Level 6 biotopes are verified using macrozoobenthic communities.•All benthic communities identified could be allocated to a corresponding biotope.•Applying the HELCOM HUB in the south-western Baltic Sea is feasible.•A valid classification is crucial for implementing regional and European directives. The HELCOM Red List biotopes project proposed a Baltic Sea wide classification consisting of six levels: The HELCOM Underwater biotopes/habitats classification system (HELCOM HUB). We present a case study from the south-western Baltic Sea where we tested the applicability of this system. More than 500 sampling stations were analyzed regarding macrozoobenthic communities and their linkage to environmental parameters. Based on the analyses of biotic and abiotic data, 21 groups were assigned to 13 biotopes of the classification. For some biotopes varying states of communities were recognized. Even though not all abiotic parameters are considered directly in the hierarchy of the classification in general, all soft-bottom communities could be allocated to a corresponding biotope. The application of the HELCOM HUB for the south-western Baltic Sea is feasible, in regard to the implementation of the European Marine Strategy Framework Directive as well as the Baltic Sea Action Plan.