Red List habitat classification > RL - Marine habitats > RLBAL - Baltic > BAL10 Kelp communities on Baltic infralittoral coarse sediment/shell gravel

Kelp communities on Baltic infralittoral coarse sediment/shell gravel

Quick facts

Red List habitat type code BAL10
Threat status
Europe Near Threatened
EU Near Threatened
Relation to
Source European Red List habitat factsheet
European Red List of habitats reports
European Red List of habitats (Excel table)


This habitat occurs in the photic zone in areas where the more than 90% of the seabed is comprised of coarse sediments, including shell gravel and mixed substrates according to the HELCOM HUB classification. Kelp covers at least 10% of the seabed and more than other perennial attached erect groups.  It is more common in areas exposed to wave action than sheltered locations and present in depths from around 0.5-10 m.  Three associated biotopes have been identified. ‘Baltic photic shell gravel dominated by kelp’ (AA.E1C4), ‘Baltic photic mixed substrate dominated by kelp’ (AA.M1C4) and Baltic photic coarse sediment dominated by kelp’ (AA.I1C4) where perennial attached kelp species such as Saccharina latissima and Laminaria digitata constitute at least 50% of the biovolume of such algae. 

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 in the Baltic Sea. The necessary environmental conditions (specific bottom morphology and currents) to enable shell gravel bottoms exist only within very few spatially restricted localities in the Baltic. Whilst these are known in general terms there is a lack of quantitative data on the extent and quality of this habitat. The current Red List assessment has therefore been based on expert opinion.
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 one of the associated biotopes (kelp on shell gravel) to be Near Threatened (based on criterion B1a (ii)). Kelp on coarse sediment and kelp on mixed substrate was assessed as Least Concern. Given the scarcity of kelp habitats on shell gravel and coarse sediment in the Baltic region, continuation of known threats, and the predicted increase in pressure on this habitat associated with climate change (temperature and salinity in particular), expert opinion has been used to assess this habitat as Near Threatened for the EU 28 and EU 28+.
Red List Category Red List Criteria
Near Threatened A1, A2, A3, B3
Red List Category Red List Criteria
Near Threatened A1, A2, A3, B3

Confidence in the assessment

Red List of habitat categories and criteria descriptions

Pressures and threats

  • Biological resource use other than agriculture & forestry
    • Fishing and harvesting aquatic resources
    • Professional active fishing
    • Benthic or demersal trawling
    • Benthic dredging
  • 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 but there are circumstances where this may not happen. For example, the very high sea temperatures in 1994 may have prevented recolonization in a 15 year period in the Flensburg Fjord Denmark. Timescale for recolonization after severe damage will also depend on whether the causes of decline such as eutrophication, have been addressed, whether the shell gravel substrate is still present and whether it remains suitable for recolonization.

Trends in extent

Average current trend in quantity

Decreasing Decreasing
EU28 EU28+

Trends in quality

Average current trend in quality

Unknown Unknown
EU28 EU28+

Conservation and management needs

All actions to reduce physical disturbance of shell gravel/mixed substrate bottoms and eutrophication in the Baltic Sea are important for the conservation of this habitat. The areas where it occurs should be protected for example by limiting or prohibiting bottom trawling, or the exploitation of oil, gas, sand or gravel.

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
  • Measures related to spatial planning
    • Establish protected areas/sites
  • Measures related to hunting, taking and fishing and species management
    • Regulation/Management of fishery in marine and brackish systems


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 max Unknown Decreasing
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 63,250 max 410 max 60,000 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 410 max 60,000 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
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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1050 Copenhagen K
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