Red List habitat classification > RL - Marine habitats > RLBAL - Baltic > BAL1 Kelp communities on Baltic infralittoral rock and mixed substrata (predominantly hard)

Kelp communities on Baltic infralittoral rock and mixed substrata (predominantly hard)

Quick facts

Red List habitat type code BAL1
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 is a Baltic Sea benthic habitat in the photic zone where at least 90% of the substrate is rock, boulders, stones and mixed (predominantly hard) substrates according to the HELCOM HUB classification. It is most common in wave exposed areas with kelp dominating the perennial algae and covering at least 10% of the seabed. Saccharina latissima and Laminaria digitata consitute at least 50% of the biovolume of such algae.  Two associated biotopes have been identified. ‘‘Baltic photic rock and boulders dominated by kelp’ (AA.A1C4) and ‘Baltic photic mixed substrate dominated by kelp’ (AA.M1C4). To identify this habitat mapping should take place during the months when the vegetation is fully developed. 

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 the kelp is a potential indicator of quality of this habitat.

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

Threat status

Synthesis of Red List assessment

This habitat is only present in the EU 28 as it is only found in the southern Baltic Sea. There is a lack of quantitative data on extent and quality, therefore this Red List assessment has been based on expert opinion. Threats and pressures on this habitat have been identified but it is not considered to have declined in extent by more than 25% over the last 50 years. Modelling studies suggest that climate change effects (on sea temperature and salinity) could lead to a reduction in extent of this habitat in the future by affecting the reproductive success of the characteristic kelp species but this has not been 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 two relevant Baltic biotopes (AA.A1C4 and AA.M1C4) to be of Least Concern (based on Criterion A1). With no additional information on changes in extent or quality of this habitat, current expert opinion is that this habitat should be assessed as Least Concern in 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)
  • Natural System modifications
    • Human induced changes in hydraulic conditions
    • Siltation rate changes, dumping, depositing of dredged deposits
    • Other human induced changes in hydraulic conditions
  • Climate change
    • Changes in abiotic conditions
    • Temperature changes (e.g. rise of temperature & extremes)
    • Changes in biotic conditions
    • Habitat shifting and alteration

Habitat restoration potential

Harvesting experiments have shown that sugar kelp has a relatively quick recolonization response following removal from an area. Improvements in water quality where this is a reason for decline (e.g. through sedimentation/eutrophication) and rock replacement have been used to allow this habitat to become re-established. Timescales vary depending on conditions but recovery could potentially occur naturally within 10 years.

Trends in extent

Average current trend in quantity

Unknown Unknown
EU28 EU28+

Trends in quality

Average current trend in quality

Unknown Unknown
EU28 EU28+

Conservation and management needs

Current approaches to the conservation and management of this habitat type include the establishment of protected areas, reduction of nutrient inputs to improve water quality and rock placement for reef habitat creation. Similar actions are likely to be continue to be beneficial to this habitat.

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)
Belt Sea Present Unknown Unknown Unknown
The Sound
Baltic Proper

Extent of Occurrence, Area of Occupancy and habitat area

Extent of Occurrence (EOO) (Km2) Area of Occupancy (AOO) Current estimated Total Area Comment
EU28 max 78,300 max 552 Unknown EOO and AOO are based on HELCOM mapping in 100 x 100km cells that were converted to 10 x 10 km cells. The values therefore represent a maximum as the habitat may not occur in all these 10 x 10 km cell
EU28+ max 552 Unknown not present in EU28+ in the Baltic
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 Chaetomorpha melagonium
Algae Delesseria sanguinea
Algae Laminaria digitata
Species scientific name English common name Species group
Chaetomorpha melagonium Algae
Delesseria sanguinea Algae
Laminaria digitata Algae

Vegetation types

Relation to vegetation types (syntaxa)

Not available

Other classifications

Not available
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