Annual algal communities on Baltic infralittoral muddy sediment
Quick facts
| Red List habitat type | code BAL35 |
|---|---|
| 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) |
Summary
This Baltic Sea benthic habitat is occurs in the photic zone with at least 90% coverage of muddy sediment according to the HELCOM HUB classification. Annual algae cover at least 10% of the seabed, while all other epibenthic biotic structures like rooted plants, unattached perennial algae or blue mussels cover less than 10%. The habitat covers the full salinity range of the Baltic Sea and is common in sheltered, very shallow areas. One associated biotope has been identified: ‘Baltic photic muddy sediment dominated by Vaucheria spp.’ (AA.H1S3). This is encountered most of the Baltic Sea with the exception of the more saline western parts (the Belt Sea and The Sound) and is identified by a large representation of Vaucheria spp., which constitutes at least 50% of the biovolume of the annual algae. It forms dense mats in bays with soft sediment, requires a salinity below 7 psu and is found at up to 7 meters depth.
Indicators of quality:
The ratio of annual to perennial epibenthic components is used in several countries to describe habitat quality. As such the area of the habitat itself or the biomass of the corresponding species is used as an indicator for quality.In this particular case the lowest area or biomass is a sign of high quality as only in very high exposure levels should annual algae dominate. In all other circumstances perennials (Fucus) should dominate except where there is a low salinity (below 3 psu) as perennial algae growth does not generally occur under such conditions.
Threat status
Synthesis of Red List assessment
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. This habitat was evaluated by HELCOM in the 2013 Red List of Habitat Assessment as Least Concern (A1). With no further baseline information or data on changes in extent or quality, the current expert opinion is an assessment of Least Concern for both the EU 28 and EU 28+.
| EU | |
| Red List Category | Red List Criteria |
| Least Concern | - |
| Europe | |
| Red List Category | Red List Criteria |
| Least Concern | - |
Confidence in the assessment
Pressures and threats
- No threats or pressures
- No threats or pressures
Habitat restoration potential
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
List of conservation and management needs
- No measures
- No measure known / impossible to carry out specific measures
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) |
|---|---|---|---|---|
| Baltic Proper | Present | Unknown | Unknown | Unknown |
| Gulf of Bothnia | ||||
| Gulf of Finland | ||||
| Gulf of Riga | ||||
| Belt Sea |
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. |
| 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).
