Perennial algal communities (excluding kelp) on Baltic infralittoral rock and mixed substrata (predominantly hard)
|Red List habitat type||code BAL2|
|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 or stones and mixed (predominantly hard) substrates 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 exposed to wave action and typically occurs to depths of around 0.5 m.
Eight associated biotopes with different dominant species of algae have been described by HELCOM. ‘Baltic photic rock and boulders/mixed substrata dominated by Fucus spp.’ (AA.A1C1/AAM1C1) such as Fucus radicans, F. serratus or F. vesiculosus, is found in depths of 0.5–5m and in salinities over 4 psu. ‘Baltic photic rock and boulders/mixed substrata dominated by perennial non-filamentous corticated red algae’ (AA.A1C2/AA.M1C2) such as Furcellaria lumbricalis occurs at a depths of 2–10 m in similar salinities. These four biotopes are present in all the Baltic Sea sub-basins and are widely distributed, although not Bothnian Bay nor the most eastern part of the Gulf of Finland. ‘Baltic photic rock and boulders/mixed substrata dominated by perennial foliose red algae’ (AA.A1C3/AA.M1C3) such as Coccotylus spp., Phyllophora spp. and Delesseria spp. is typically found in depths of 2–10 m and in salinities over 4 psu. They are present in all the Baltic Sea sub-basins and are also widely distributed although also not in the Bothnian Bay nor the eastern half of the Gulf of Finland. ‘Baltic photic rock and boulders/mixed substrata dominated by perennial filamentous algae’ (AA.A1C5/AA.M1C5) such as Polysiphonia spp, Aegagrophila linnaei, Cladophora rupestris is found at depths of 0.5–10 m, in all the Baltic Sea sub-basins.
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.
Synthesis of Red List assessment
Reduction in habitat quality has also been apparent in some areas as changes in the algal and faunal species composition. This has been reported as an increase of abundance of smothering and fast growing filamentous annual macroalgae. There are concerns about possible future declines in extent and quality of this habitat. For example it has been suggested that if trends in temperature, total phosphorus concentration and chlorophyll a continue, water quality in the Bothnian Sea will deteriorate within 2-3 decades and reach levels that may lead to major losses of F. vesiculosis.
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 eight relevant Baltic biotopes to be of Least Concern (based on criterion A1). With no additional information on changes in extent or quality of this habitat, a restricted distribution, and less than a 25% decline in quantity over the last 50 years, current expert opinion is that this habitat should be assessed as Least Concern for both the EU 28 and EU 28+.
|Red List Category||Red List Criteria|
|Red List Category||Red List Criteria|
Confidence in the assessment
Pressures and threats
- Mining, extraction of materials and energy production
- Mining and quarrying
- Renewable abiotic energy use
- 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
- Changes in abiotic conditions
- Temperature changes (e.g. rise of temperature & extremes)
- Habitat shifting and alteration
Habitat restoration potential
Trends in extent
Average current trend in quantity
Trends in quality
Average current trend in quality
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
- Other marine-related measures
- Measures related to spatial planning
- Establish protected areas/sites
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)|
|Gulf of Bothnia|
|Gulf of Finland|
|Gulf of Riga|
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||Present in all the Baltic sub-basins|
|EU28+||>50||Unknown||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).