German Federal Agency for Nature Conservation (BfN)


Western Rønne Bank SAC

Transcript of the Western Rønne Bank SAC video

Rønne Bank consists of several terminal moraines extending from the south coast of Bornholm to about 10 nautical miles north-east of Rügen. The approximately 86 km² Rønne Bank protected area encompasses the western slope of Rønne Bank in the 22 m to 35 m depth range. The sea floor is dominated by patches of residual sediment with large scattered boulders and cobble fields. About 65 km2 of the area is consequently classified as reef as defined in the Habitats Directive.

Fact sheet for Western Rønne Bank SAC
(In German)
Western Rønne Bank
EU-Code: DE 1249-301
(In German)
Coordinate of Centroid:
13°59'00" E 54°42'00" N
Habitat types Reefs ca. 65 km²
Species/Population Harbour porpoise
(Phocoena phocoena)    

Species found in the Western Rønne Bank SAC

Boulder thickly overgrown with mussels. Photo: Hübner/Krause (BfN)
Photo: Boulder thickly overgrown with mussels. Photo: Hübner/Krause (BfN)
Ideal conditions for Cod (Gadus morhua) . Photo: Hübner/Krause (BfN)
Photo: Ideal conditions for Cod (Gadus morhua). Photo: Hübner/Krause (BfN)

The prevailing geohydrological conditions (including low salinity levels) result in flora and fauna that are relatively poor in species numbers but unique in form and rich in numbers of individuals. Boulders are mostly colonised by blue mussels of various shapes and sizes. Red algae are also found, although in far smaller quantities than in the Fehmarn Belt or the Kadet Trench and not to the same depths. Other characteristic species make up epifauna communities including barnacles, amphipods and rockpool prawns. Fish species such as eel, two-spotted and black goby, eelpout and cod find ample food and sufficient shelter.

Eel pout (Zoarces viviparus) hiding. Photo: Hübner/Krause (BfN)
Photo: Eel pout (Zoarces viviparus) hiding. Photo: Hübner/Krause (BfN)

Even at depths of 25 m, the water here is so clear that the summer sun causes the stony bottom to gleam in a greenish light. Mussels closely cover the embanked boulders as far as the eye can see. Large cod flit past using the shelter offered by the reefs.

Other Habitats Directive Annex II covered by the conservation objectives are harbour porpoise and twait shad. 

The harbour porpoise so far recorded in the protected area are presumably individuals from the severely endangered subpopulation of the eastern Baltic Sea using the area as a migration or living and foraging habitat. A mother-calf pair has also been sighted. As harbour porpoise are very rarely seen in this area of sea, the sightings made to date are particularly important. Germany’s commitments under the Agreement on the Conservation of Small Cetaceans of the Baltic and North Seas (ASCOBANS) and the Habitats Directive include binding obligations to re-establish the endangered populations of this species in German waters and conserve important habitats.

Conservation objectives

General conservation objectives have been set as follows for the habitat types and species by which the site is defined:

  • Maintenance and restoration of the site’s specific ecological functions, biological diversity and natural hydrodynamics
  • Maintenance and restoration at favourable conservation status of habitat type Code 1170 (reefs) together with its characteristic and endangered ecological communities and species
  • Maintenance and restoration at favourable conservation status of the harbour porpoise, a Habitats Directive Annex II species, and its natural habitats (among other things under the ASCOBANS Recovery Plan for Harbour Porpoise in the Central Baltic)

Mussel beds, home to many fauna species. Photo: Hübner/Krause (BfN)
Photo: Mussel beds, home to many fauna species. Photo: Hübner/Krause (BfN)

Natura 2000 sites in the German Baltic Sea EEZ:


Baltic Sea

Fehmarn Belt

Kadet Trench

Adler Ground

Western Rønne Bank

Odra Bank

Pomeranian Bay