Red List habitat classification > RL - Marine habitats > RLBAL - Baltic > BAL58 Infaunal communities of Baltic upper circalittoral muddy sediment not dominated by bivalves

Infaunal communities of Baltic upper circalittoral muddy sediment not dominated by bivalves

Quick facts

Red List habitat type code BAL58
Threat status
Europe Least Concern
EU Least Concern
Relation to
Source European Red List habitat factsheet
European Red List of habitats reports
European Red List of habitats (Excel table)


This habitat is distributed on Baltic aphotic bottoms with at least 90% coverage of muddy sediment according to the HELCOM HUB classification. Sessile/semi-sessile epibenthic macrofauna are generally not present and infaunal polychaetes/crustaceans/echinoderms/or insect larvae dominate in terms of biomass. This habitat typically occurs below approximately 20 m depth and is present in all energy exposure classes and in all the Baltic sub-basins. Four  associated biotopes have been identified: these are characterized by infaunal polychaetes where species such as Polydora ciliata, Lagis koreni, Capitella capitata, Scoloplos (Scoloplos) armiger constitute at least 50% of the infaunal biomass; by infaunal crustaceans  where the benthic amphipods Monoporeia affinis and/or Pontoporeia femorata dominateor where  insect larve where (Chironomidae) or echinoderms dominate the biomass. M. affinis is an important food source for several fish species, such as cod (Gadus morhua), herring (Clupea harengus), smelt (Osmerus eperlanus) and fourhorn sculpin (Myoxocephalus quadricornis). In favourable conditions, M. affinis and Pontoporeia femorata can occur in great abundances, even several thousand individuals per square meter. 

Indicators of quality:  

Both biotic and abiotic indicators have been used to describe marine habitat quality. These include: the presence of characteristic species as well as those which are sensitive to the pressures the habitat may face; water quality parameters; levels of exposure to particular pressure, and more integrated indices which describe habitat structure and function, such as trophic index, or successional stages of development in habitats that have a natural cycle of change over time. There are no commonly agreed indicators of quality for this habitat, although particular parameters may have been set in certain situations e.g. protected features within Natura 2000 sites, where reference values have been determined and applied on a location-specific basis. Diversity, abundance and biomass of fauna may be indicators of quality.

Characteristic species
For full habitat description, please download the habitat factsheet.

Threat status

Synthesis of Red List assessment

The presence of this habitat type in the Baltic is well established and it is known to occur in all the sub-basins. There have been various changes in the associated biotopes over the last 50 years. For example M. affinis and P. femorata decreased drastically in the late 1970s early 1980s in the northern Baltic. By early 1990s P. femorata vanished and M. affinis abundance was low. This decline was followed by increase in M. balthica and arrival of Marenzellaria in the 1992. There are a lack of quantitative data on current and historic trends relating to this habitat and no estimates have been made of future trends.
The overall assessment for this EUNIS level 4 habitat has been based on the HELCOM (2013) assessments for the associated HELCOM HUB biotopes. Draft assessments were derived using a weighted approach whereby the HELCOM assessment outcomes were assigned a score. This was averaged across the relevant biotopes. The outcomes were reviewed by Baltic experts to reach a final conclusion. HELCOM assessed four associated biotopes (AB.H3M1, AB.H3M3, AB.H3M5 and AB.H3P1) as Least Concern (A1). Biotope AB.H3N1 was assessed as Near Threatened (A1). With no additional data available the current expert opinion is that this habitat should be assessed as Least Concern for both the EU 28 and EU 28+.
Red List Category Red List Criteria
Least Concern -
Red List Category Red List Criteria
Least Concern -

Confidence in the assessment

Red List of habitat categories and criteria descriptions

Pressures and threats

  • Pollution
    • Pollution to surface waters (limnic, terrestrial, marine & brackish)
    • Nutrient enrichment (N, P, organic matter)
    • Input of contaminants (synthetic substances, non-synthetic substances, radionuclides) - diffuse sources, point sources, acute events

Habitat restoration potential


Trends in extent

Average current trend in quantity

Stable Stable
EU28 EU28+

Trends in quality

Average current trend in quality

Unknown Unknown
EU28 EU28+

Conservation and management needs

All actions to reduce the level of eutrophication on the scale of the whole Baltic Sea will benefit this habitat. The invasive polychaete Marenzelleria spp. has already had an effect in areas previously dominated by Monoporeia affinis and/or Pontoporeia femorata and unfortunately very little can be done to reduce the population of the polychaete worms in the Baltic Sea. Measures can however be taken to hinder the spread of new invasive species into the Baltic Sea.

List of conservation and management needs

  • Measures related to wetland, freshwater and coastal habitats
    • Restoring/Improving water quality
  • Measures related to marine habitats
    • Other marine-related measures
    • Restoring marine habitats


For each habitat a distribution map was produced from a wide variety of sources indicating known and potential occurrences of the habitat in 10x10 km grids within Europe. Occurrences in grid cells were given in two classes: actual distribution from relatively reliable sources (surveys, expert knowledge), and potential distribution based on models or less reliable indicators. Please download the fact sheet to see the map.

Geographic occurrence and trends

Seas Present or presence uncertain Current area of habitat (Km2) Recent trend in quantity (last 50 years) Recent trend in quality (last 50 years)
Baltic Proper Present Unknown Unknown Decreasing
Belt Sea
Gulf of Bothnia
Gulf of Finland
Gulf of Riga
The Sound

Extent of Occurrence, Area of Occupancy and habitat area

Extent of Occurrence (EOO) (Km2) Area of Occupancy (AOO) Current estimated Total Area Comment
EU28 >50,000 >50 Unknown This habitat is common and present in all the Baltic sub-basins.
EU28+ >50 Unknown This habitat is common and present in all the Baltic sub-basins.
AOO = the area occupied by a habitat measured in number of 10x10 km grid cells.
EOO = the area (km2) of the envelope around all occurrences of a habitat (calculated by a minimum convex polygon).

Characteristic species

Not available

Vegetation types

Relation to vegetation types (syntaxa)

Not available

Other classifications

Not available
European Environment Agency (EEA)
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