Red List habitat classification > RL - Marine habitats > RLBAL - Baltic > BAL11 Perennial algal communities (excluding kelp) on Baltic infralittoral coarse sediment

Perennial algal communities (excluding kelp) on Baltic infralittoral coarse sediment

Quick facts

Red List habitat type code BAL11
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 bottomsin the photic zone with at least 90% coverage of coarse sediment according to the HELCOM HUB classification.  Perennial attached algae such as Fucus spp., or perennial red algae cover at least 10% of the seabed and more than other perennial attached erect groups.  It is most common in areas moderately exposed to wave action and in depths of up to 10 m. 

Four associated biotopes with different dominant species of algae and some differences in depth and salnity preferences, resulting in variations in their geographical occurrence in the Baltic Sea have been described by HELCOM. These are: ‘Baltic photic coarse sediment dominated by Fucus spp.’ (AA.I1C1) such as Fucus radicans, F. serratus or F. vesiculosus: ‘Baltic photic coarse sediment dominated by perennial non-filamentous corticated red algae’ (AA.I1C2) such as Furcellaria lumbricalis; ‘Baltic photic coarse sediment dominated by perennial foliose red algae’ (AA.I1C3) such as Coccotylus spp., Phyllophora spp. and Delesseria spp. and  ‘Baltic photic coarse sediment dominated by perennial filamentous algae’ (AA.I1C5) such as Polysiphonia spp, Aegagrophila linnaei, Cladophora rupestris

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. The lower depth limit of algae, especially Fucus spp. where applicable, and the amount of epiphytic algae are potential indicators of quality of this habitat.

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

Threat status

Synthesis of Red List assessment

Modelling and mapping studies provide information on the location and extent of the habitat in some areas (e.g. Lithuania and Poland) but there is a lack of quantitative data on the full extent of this habitat in the Baltic Sea. Significant changes most particularly in its depth distribution, but also in quality have been reported over the last 60 years but not quantified.
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 four relevant Baltic biotopes (AA.I1C1, AA.I1C2, AA.I1C3, AA.I1C5) to be Least Concern (A1). With no additional information on changes in extent or quality of this habitat, a wide geographical distribution in the Baltic and less than a 25% decline in quantity over the last 50 years, the current expert opinion is that this habitat should be assessed as Least Concern for 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
  • Natural System modifications
    • Human induced changes in hydraulic conditions
    • Siltation rate changes, dumping, depositing of dredged deposits
  • Climate change
    • Temperature changes (e.g. rise of temperature & extremes)
    • Habitat shifting and alteration

Habitat restoration potential


Trends in extent

Average current trend in quantity

Decreasing Decreasing
EU28 EU28+

Trends in quality

Average current trend in quality

Decreasing Decreasing
EU28 EU28+

Conservation and management needs

Improvements in water quality (reduction of nutrient inputs) are considered to have been a major factor in the recovery of the perennial macroalgal habitat by improving light penetration and reducing the scope for rapid and blanketing smothering of the canopy forming species by ephiphytic annual algae. Controls on coastal and offshore constructions to avoid increasing turbidity and direct removal or damage to the habitat are also important.

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


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 670 Decreasing 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 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

The full list of characteristic species and genus are available above from the Summary. The species available in the EUNIS database are shown here.
Algae Cladophora rupestris
Algae Coccotylus truncatus
Algae Furcellaria lumbricalis
Species scientific name English common name Species group
Cladophora rupestris Algae
Coccotylus truncatus Algae
Furcellaria lumbricalis Algae

Vegetation types

Relation to vegetation types (syntaxa)

Not available

Other classifications

Not available
European Environment Agency (EEA)
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