Baltic Marine Environment
Protection Commission

Red List of Biotopes and Habitats

A Red List threat assessment was made for 209 biotopes of which 59 were red-listed. Of the assessed biotopes, 73% were classified LC and are therefore currently not seen to be at risk of collapse.

Only one biotope was categorized in the most severe threat category CR, the biotope delineated by aphotic muddy bottoms dominated by the ocean quahog (Arctica islandica) mussel. The Red List assessment results indicate that many of the threatened biotopes occur in the deep areas of the Baltic Sea. The reason for most of these biotopes becoming threatened is eutrophication, indirectly causing oxygen depletion in the deep areas. Many of the deep biotopes occurring on soft sediments have declined due to destructive fishing methods such as bottom trawling. Furthermore, many of the red-listed biotopes occur in the southwestern Baltic Sea due to the salinity restricted distribution of the species that are characteristic of the biotope.

Data availability is relatively poor for many biotopes and long time series are generally lacking. Therefore the threat assessment is supported by expert judgement. The confidence in the threat assessment is described as High (H), Medium (M) or Low (L).

The assessment methodology is described in detail in the BSEP138 Red List of Baltic Sea underwater biotopes, habitats and biotope complexes.

Biotope codeBiotope/Habitat nameThreat categoryConfidence of threat assessmentCriterion for assessment
AB.H3L3Baltic aphotic muddy sediment dominated by ocean quahog (Arctica islandica)CRMA2
AA.M1Q2Baltic photic mixed substrate dominated by stable aggregations of unattachedFucus spp. (dwarf form)ENLA1
AA.H1Q2Baltic photic mud dominated by stable aggregations of unattached Fucus spp. (dwarf form)ENLA1
AA.I1Q2Baltic photic coarse sediment dominated by stable aggregations of unattachedFucus spp. (dwarf form)ENLA1
AA.J1Q2Baltic photic sand dominated by stable aggregations of unattached Fucus spp. (dwarf form)ENLA1
AA.DBaltic photic maerl beds (unattached particles of coralline red algae)ENMB1+2a(ii) 
AB.DBaltic aphotic maerl beds (unattached particles of coralline red algae)ENLB1+2a(ii) 
AB.B1E4Baltic aphotic hard clay dominated by Astarte spp.ENMB2c(ii) 
AB.H3L5Baltic aphotic muddy sediment dominated by Astarte spp.ENMA1
AB.H2T1Baltic aphotic muddy sediment characterized by sea-pensENMA1
AB.H1I2Baltic aphotic muddy sediment dominated by Haploops spp.ENMA1
AE.O5Baltic Sea aphotic pelagic below halocline oxicENLA3
AA.GBaltic photic peat bottomVUMB2b
AB.J3L3Baltic aphotic sand dominated by ocean quahog (Arctica islandica)VUMA1
ACBaltic Sea seasonal iceVULA1+2a
AA.E1F1Baltic photic shell gravel dominated by vase tunicate (Ciona intestinalis)VULB1a(ii)
AB.E1F1Baltic aphotic shell gravel dominated by vase tunicate (Ciona intestinalis)VULB1a(ii)
AA.E3YBaltic photic shell gravel characterized by mixed infaunal macrocommunity in fine sand-like shell fragmentsNTLB1a(ii)
AB.E3YBaltic aphotic shell gravel characterized by mixed infaunal macrocommunity in fine sand-like shell fragmentsNTLB1a(ii)
AA.E1C4Baltic photic shell gravel dominated by kelpNTLB1a(ii)
AA.A1H2Baltic photic rock and boulders dominated by erect moss animals (Flustra foliacea)NTLA1
AB.A1H2Baltic aphotic rock and boulders dominated by erect moss animals (Flustra foliacea)NTLA1
AA.M1H2Baltic photic mixed hard and soft substrates dominated by erect moss animals (Flustra foliacea)NTLA1
AB.M1H2Baltic aphotic mixed hard and soft substrates dominated by erect moss animals (Flustra foliacea)NTLA1
AA.H1B4Baltic photic muddy sediment dominated by CharalesNTMA1
AA.I1B4Baltic photic coarse sediment dominated by CharalesNTLA1
AA.J1B4Baltic photic sand dominated by CharalesNTLA1
AA.M1B4Baltic photic mixed substrate dominated by CharalesNTLA1
AA.H1B7Baltic photic muddy sediment dominated by common eelgrass (Zostera marina)NTMA1
AA.I1B7Baltic photic coarse sediment dominated by common eelgrass (Zostera marina)NTMA1
AA.J1B7Baltic photic sand dominated by common eelgrass (Zostera marina)NTMA1
AA.M1B7Baltic photic mixed substrate dominated by common eelgrass (Zostera marina)NTMA1
AA.H1A2Baltic photic muddy sediment dominated by sedges (Cyperaceae)NTMA1
AA.H1B5Baltic photic muddy sediment dominated by spiny naiad (Najas marina)NTMA1
AA.J1B5Baltic photic sand dominated by spiny naiad (Najas marina)NTLA1
AA.H3L3Baltic photic muddy sediment dominated by ocean quahog (Arctica islandica)NTMA1
AA.J3L3Baltic photic sand dominated by ocean quahog (Arctica islandica)NTMA1
AA.H3L6Baltic photic muddy sediment dominated by UnionidaeNTLA1
AA.I3L10Baltic photic coarse sediment dominated by multiple infaunal bivalve species: Macoma calcarea, Mya truncata, Astartespp., Spisula spp.NTLA1
AB.I3L10Baltic aphotic coarse sediment dominated by multiple infaunal bivalve species: Macoma calcarea, Mya truncataAstartespp., Spisula spp.NTLA1
AA.J3L10Baltic photic sand dominated by multiple infaunal bivalve species: Macoma calcarea, Mya truncata, Astarte spp., Spisulaspp.NTLA1
AB.J3L10Baltic aphotic sand dominated by multiple infaunal bivalve species: Macoma calcarea, Mya truncataAstarte spp., Spisulaspp.NTLA1
AA.I3L11Baltic photic coarse sediment dominated by multiple infaunal polychaete species includingOphelia spp. (disregarding present bivalves)NTLA1
AB.I3L11Baltic aphotic coarse sediment dominated by multiple infaunal polychaet species includingOphelia spp. (disregarding present bivalves)NTLA1
AA.J3L11Baltic photic sand dominated by multiple infaunal polychaete species including Ophelia spp. and Travisia forbesii(disregarding present bivalves)NTLA1
AB.J3L11Baltic aphotic sand dominated by multiple infaunal polychaete species including Ophelia spp. and Travisia forbesii(disregarding present bivalves)NTLA1
AB.A1F1Baltic aphotic rock and boulders dominated by sea squirts (Ascidiacea)NTLA1
AB.M1F1Baltic aphotic mixed hard and soft substrates dominated by sea squirts (Ascidiacea)NTLA1
AB.A1G2Baltic aphotic rock and boulders dominated by sea anemons (Actiniarida)NTLA1
AB.M1G2Baltic aphotic mixed hard and soft substrates dominated by sea anemons (Actiniarida)NTLA1
AB.A1G3Baltic aphotic rock and boulders dominated stone corals (Scleractinida)NTLA1
AB.M1G3Baltic aphotic mixed hard and soft substrates dominated stone corals (Scleractinida)NTLA1
AB.A1G4Baltic aphotic rock and boulders dominated by soft corals (Alcyonacea)NTLA1
AB.M1G4Baltic aphotic mixed hard and soft substrates dominated by soft corals (Alcyonacea)NTLA1
AB.A1JBaltic aphotic rock and boulders dominated by sponges (Porifera)NTLA1
AB.M1JBaltic aphotic mixed hard and soft substrates dominated by sponges (Porifera)NTLA1
AB.H3N1Baltic aphotic muddy sediment dominated by Monoporeia affinis and/or Pontoporeia femorataNTMA1
AB.H4U1Baltic aphotic muddy sediment dominated by meiofaunaNTLA1
AB.J3L7Baltic aphotic sand dominated by striped venus (Chamelea gallina)NTLA1