Red List habitat classification > RL - Marine habitats > RLBAL - Baltic > BAL27 Annual algal communities on Baltic infralittoral sand

Annual algal communities on Baltic infralittoral sand

Quick facts

Red List habitat type code BAL27
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 benthic Baltic Sea habitat occurs in the photic zone with at least 90% coverage of sand according to the HELCOM HUB classification. Annual algae cover at least 10%, while all other epibenthic biotic structures like rooted plants, unattached perennial algae or blue mussels cover less than 10%. The habitat occurs in the full salinity range of the Baltic Sea and is more common in moderate to sheltered, very shallow areas.

Two associated biotopes with different dominant species of algae (at least 50% of the biovolume of the annual algae) have been identified. ‘Baltic photic sand dominated by Chorda filum and/or Halosiphon tomentosus’ (AA.J1S2) usually down to a depth of 4 meters, in areas moderately exposed to wave action. These species give the appearance of growing on the sand but attach to small fractions of stable substrate like small stones, shell fragments or gravel buried in the sand. It is distributed in the whole Baltic Sea except in the most northern part of the Bothnian Bay.  A second associated biotope, ‘Baltic photic sand dominated by Vaucheria spp.’ (AA.J1S3), is usually present down to a depths of 7 meters, in areas more sheltered areas and in salinities less than 7 psu. It is distributed in the whole Baltic Sea except for the Belt Sea and the Sound.

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.


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

Threat status

Synthesis of Red List assessment

This habitat is present in all the sub-basins of the Baltic Sea with site records and distribution maps available for some of the characteristic species. There is a lack of quantitative data but expert opinion is that the extent has been stable over the past 50 years. No significant changes in extent or quality are envisaged for the near future.
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 (2013) assessed the two relevant Baltic biotopes (AA.J1S1 and AA.J1S2) as Least Concern (A1). With no additional information on changes in extent or quality of this habitat, the current expert opinion is an assessment of 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

  • No threats or pressures
    • No threats or pressures

Habitat restoration potential

As the dominant species of this habitat are annuals, often known as opportunists with short life cycles, recovery can be very fast (1-2 years) even after strong declines.

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

No conservation and management measures specific to this habitat have been identified.

List of conservation and management needs

  • No measures
    • No measures needed for the conservation of the habitat/species


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 Stable
Gulf of Bothnia
Gulf of Finland
Gulf of Riga
The Sound
Belt Sea

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 present in all the Baltic sub-basins.
EU28+ >50 Unknown This habitat is 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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