Submerged rooted plant communities on Baltic infralittoral coarse sediment
Quick facts
Red List habitat type | code BAL15 |
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Threat status | |
Europe | Near Threatened |
EU | Near Threatened |
Relation to |
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Source | European Red List habitat factsheet |
European Red List of habitats reports | |
European Red List of habitats (Excel table) |
Summary
This benthic habitat occurs in the photic zone with at least 90% coverage of coarse sediment according to the HELCOM HUB classification. Coarse sediments covered by rooted plants (which also includes plants with rhizoids,i.e. Charales) are mainly distributed in areas of moderate exposure to wave actioin. The habitat covers the full salinity range of the Baltic Sea and is distributed from the Belt Sea up to the northern part of Bothnian Bay. Depending on the salinity the dominant species (>50% of the biovolume), defining the associated biotope type, varies. They also occupy different depth zones. Five associated biotopes have been identified: ’Baltic photic coarse sediment dominated by pondweed (Potamogeton perfoliatus and/or Stuckenia pectinata)’ (AA.I1B1); ’Baltic photic coarse sediment dominated by Ranunculus spp.’ (AA.I1B6 ); ’Baltic photic coarse sediment dominated by Charales’ (AA.I1B4); ’Baltic photic coarse sediment dominated by Zannichellia spp. and/or Ruppia spp. and/or Zostera noltei’ (AA.I1B2) and ’Baltic photic coarse sediment dominated by common eelgrass (Zostera marina)’ (AA.I1B7).
The latter differs most strongly from the other biotopes in distribution, occurring mainly at moderate to high exposure and in salinities of 5 psu or higher. It is typically found in deeper waters 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 the 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 species, 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.
Threat status
Synthesis of Red List assessment
There have been significant declines (>25%) in the extent of the seagrass and charophyte dominated communities in the last 50 years and in the quality of some of the associated biotopes. Zostera marina and several species of charophyts are also on the HELCOM Red List of threatened species in the Baltic. 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 AA.I1B1, AA.I1B2 and AA.I1B6 as Least Concern (A1) and AA.I1B4 and AA.I1B7 as Near Threatened (A1). With no additional information on changes in extent or quality of this habitat the overall assessment for this habitat type based on expert opinion is Near Threatened fro both the EU 28 and EU 28+.
EU | |
Red List Category | Red List Criteria |
Near Threatened | A1 |
Europe | |
Red List Category | Red List Criteria |
Near Threatened | A1 |
Confidence in the assessment
Pressures and threats
- Biological resource use other than agriculture & forestry
- Marine and Freshwater Aquaculture
- Intensive fish farming, intensification
- Professional active fishing
- Benthic or demersal trawling
- 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
- Removal of sediments (mud...)
- 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
Trends in extent |
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Average current trend in quantity |
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Decreasing ![]() |
Decreasing ![]() |
EU28 | EU28+ |
Trends in quality |
|
Average current trend in quality |
|
Unknown ![]() |
Unknown ![]() |
EU28 | EU28+ |
Conservation and management needs
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
Distribution
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) |
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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 | 732,697 | 434 | Unknown | This habitat is present in all the Baltic sub-basins. |
EU28+ | >50 | Unknown | This habitat is present in all the Baltic sub-basins |
EOO = the area (km2) of the envelope around all occurrences of a habitat (calculated by a minimum convex polygon).
Characteristic species
Species scientific name | English common name | Species group |
---|---|---|
Potamogeton perfoliatus | Flowering Plants | |
Ruppia cirrhosa | Flowering Plants | |
Stuckenia pectinata | Flowering Plants | |
Zannichellia palustris | Flowering Plants | |
Zostera marina | Flowering Plants |