Red List of European Habitats
Habitat code & name
AA.B1E–Baltic photic hard clay characterized by epibenthic bivalves
Author and Date
HELCOM RED LIST Biotope Expert Team, November 2013.
Relationship to EUNIS
The biotope does not correspond directly to any EUNIS (2004) level 4 habitats due to
structural differences the classification systems and the lack of the substrate ‘hard clay’ in
the relevant depth zones in the EUNIS-classification system. The closest correspondence in
EUNIS is found in the level 2 habitat ‘A4: Circalittoral rock and other hard substrata’.
Habitat description
Baltic photic zone bottoms with at least 90% coverage of hard clay. Sessile/semi-sessile
epibenthic bivalves cover of at least 10% of the seabed. Substrate is hard clay. Depth
range: photic zone. The habitat is typically encountered in high energy exposure areas.
One sub-biotope has been identified: ‘Baltic photic hard clay dominated by Mytilidae’
AA.B1E1. This sub-biotope is identified by a large representation of Mytilidae, at least 50%
of the biomass among the epibenthic bivalves.
Characteristic species
Mytilus spp., Modiolus modiolus
Indicators of quality
Diversity, abundance and biomass of fauna.
Relationships with other schemes
Annex 1 relationships
The relationship between HUB biotopes and Annex 1 habitats has not yet been mapped
by HELCOM.
MAES relationships
Marine - Marine inlets and transitional waters
Marine - Coastal
MSFD relationships
Closest correspondence to
Shallow sublittoral rock & biogenic reef
Shelf sublittoral rock & biogenic reef
EUSeaMap relationships
Closest correspondence to
Shallow photic rock or biogenic reef
Shelf photic rock or biogenic reef
IUCN ecosystem relationships
Closest correspondence to 9.2 Subtidal rock and rocky reefs
Other relationships
Level 5 of the HELCOM HUB classification (2013). This habitat has one sub-habitat on HUB
level 6; ‘Baltic photic hard clay dominated by Mytilidae’ (AA.B1E1).
This habitat is also listed in the OSPAR list of threatened biotopes (Modiolus modiolus
beds). It is encountered in the OSPAR Region II (including Kattegat) where it is listed
threatened and/or declining.
Photograph
No photograph currently available for this habitat.
Countries list
To be inserted when data sheets completed.
Regional Sea
Baltic Sea
Baltic Proper
Belt Sea
Gulf of Bothnia
Gulf of Finland
Gulf of Riga
The Sound
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Map
This will be inserted by NatureBureau based on the Regional Sea information above.
References
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