Red List habitat classification > RL - Marine habitats > RLBAL - Baltic > BAL28 Submerged rooted plant communities on Baltic infralittoral sand

Submerged rooted plant communities on Baltic infralittoral sand

Quick facts

Red List habitat type code BAL28
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 is a Baltic Sea benthic habitat in the photic zone where at least 90% of the substrate is sand according to the HELCOM HUB classification. Submerged rooted plants, including plants with rhizoids (i.e. Charales) cover at least 10% of the seabed and more than other perennial attached erect groups. The habitat is present across the full salinity range of the Baltic, in locations that are moderately to very sheltered from wave action and in depths of up to 6m. 

Eight associated biotopes with different dominant (>50% of the biovolume) macrophyte taxa (spiny naiad, spikerush, pondweed, watermilfoil, Ranunculus spp. Charales, and seagrass.) have been described.  They differ in their distribution along gradients in salinity, depth and wave exposure with the biotope dominated by the common eelgrass (Zostera marina)’ (AA.J1B7) differing most strongly from the others in distribution. This occurs mainly under conditions of moderate exposure to wave action and in salinities of 5 psu or higher. It is also typically found deeper than the other biotopes (1-6 m) and often marks the lower depth limit distribution of soft bottom vegetation. This biotope is absent from areas with low salinity in the inner part of Gulf of Finland and Gulf of Bothnia. 

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 vertical depth limit of submerged rooted plants is used in several countries as a Water Framework Directive parameter for assessing ecological status. The overall quality and continued occurrence of this habitat is, however, largely dependent on the presence of the rooted plant communities which create the biogenic structural complexity on which the characteristic associated communities depend. The density and the maintenance of a viable population of these species is a key indicator of habitat quality, together with the visual evidence of presence or absence of physical damage.

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 known with different submerged rooted plant communities dominating depending on the salinity and exposure. There are quantitative data for some of the associated biotopes in some areas (e.g. in Isefjord, Kalundborg fjord and Flensborg Fjord in Denmark and along the entire German coastline) as well as maps indicating presence in 100 x 100 km squares prepared by HELCOM. There have been significant declines (>25%) in the extent of the seagrass and charophyte dominated communities in the last 50 years. Zostera marina and several species of Charales are on the HELCOM Red List of threatened species in the Baltic. Deeper water eelgrass meadows are at risk of disappearing in the future if there is continued reduction in light levels (e. g. due to eutrophication or sediment disturbance).
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 biotopes AA.J1B1, AA.J1B2, AA.J1B3, AA.J1B6 and AA.J1B8 as Least Concern (A1). Biotopes AA.J1B4, AA.J1B5 and AA.J1B7 were assessed as Near Threatened (A1). On the basis of these assessments and expert opinion, this habitat is assessed as Near Threatened for both the EU 28 and EU 28+ since there has been a significant decline in the area of some of the biotopes with the overall decline estimated to be between 25-30%.
Red List Category Red List Criteria
Near Threatened A1
Red List Category Red List Criteria
Near Threatened A1

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
    • Estuarine and coastal dredging
    • Dykes, embankments, artificial beaches, general
    • Sea defense or coast protection works, tidal barrages
  • 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

The associated biotope AA.J1B7 ’Baltic photic sand dominated by common eelgrass (Zostera marina)’ can be slow to recover after strong decline (>20 yrs)> intervention (through transplantation) may speed up the recovery but transplantation experiments have had limited success to date. Regeneration from root systems is slow and recovery of entire beds, with characteristic structure and associated species will take long. In the northern Baltic low salinity means that any expansion takes place vegetatively. Zostera plants are believed to be from the same genotype, estimated to be between 800-1600 years old. Clonal growth and low genetic diversity may reduce the acclimation capacity and survival of the species in rapidly changing environmental conditions. For the other biotopes natural recovery can probably occur within 10 years.

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 eutrophication of the Baltic Sea are important for the conservation of this habitat. For the associated biotopes that mainly occur in bays with limited water exchange with the open ocean (those dominated by Charales’ and the spiny naiad), combating local sources of eutrophication is essential. Conservation measures are also important, such as area protection and restrictions on coastal works and dredging in shallow coastal lagoons and archipelago areas.

List of conservation and management needs

  • Measures related to wetland, freshwater and coastal habitats
    • Restoring/Improving water quality
  • Measures related to marine habitats
    • Restoring marine habitats
  • Measures related to spatial planning
    • Establish protected areas/sites
  • Measures related to urban areas, industry, energy and transport
    • Other measures
    • Managing marine traffic


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 present in all the Baltic sub-basins however there is insufficient information for accurate calculation of EOO and AOO.
EU28+ >50 Unknown This habitat is present in all the Baltic sub-basins however there is insufficient information for accurate calculation of EOO and AOO.
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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