Unvegetated communities on Baltic infralittoral shell gravel
Quick facts
| Red List habitat type | code BAL20 |
|---|---|
| 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) |
Summary
This Baltic Sea benthic habitat occurs on with at least 90% coverage of shell gravel according to the HELCOM HUB classification. Four biotopes and two sub-biotopes have been associated with this habitat. The sub-biotope 'Baltic photic shell gravel dominated by Mytilidae’ (AA.E1E1), sessile/semi-sessile epibenthic bivalves cover at least 10% of the seabed and more than other perennial attached erect groups. This biotope is identified by a large representation of Mytilidae, at least 50% of the biomass among the epibenthic bivalves and often encountered in high energy exposure areas. It has been reported from the Baltic proper and Belt Sea. 'Baltic photic shell gravel dominated by vase tunicate (Ciona intestinalis) (AA.E1F1) is ony reported from the Belt Sea and occurs in areas where the bottom consists largely of mollusc shells or small shell fragments, often constituting small patches inside other sediments. Due to the combination of the extended interstitial space and the presence of biotic hard substrates, it is inhabited by a unique combination of endobenthic and epibenthic species, such as the vase tunicate (Ciona intestinalis). The biotopes 'Baltic photic shell gravel characterized by sparse or by mixed epibenthic macrocommunities (AA.E2T and AA.E1V)' are characterised by a low (0-10%) coverage of macroscopic vegetation or sessile macroscopic epifauna and most often encountered in high energy exposure areas.
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.
Threat status
Synthesis of Red List assessment
There is a lack of quantitative data on baseline conditions and trends in quantity and quality of this habitat but declines of between 30-50% have been reported for one of the associated biotopes. Because of an estimated overall decline of 25% and likely future declines (linked to ocean acidification, eutrophication and activities which directly disturb the seabed) this habitat has been assessed as Near Threatened for both the EU 28 and EU 28+.
| EU | |
| Red List Category | Red List Criteria |
| Near Threatened | A1, A2a |
| Europe | |
| Red List Category | Red List Criteria |
| Near Threatened | A1, A2a |
Confidence in the assessment
Pressures and threats
- Mining, extraction of materials and energy production
- Exploration and extraction of oil or gas
- 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)
- Input of contaminants (synthetic substances, non-synthetic substances, radionuclides) - diffuse sources, point sources, acute events
- Natural System modifications
- Human induced changes in hydraulic conditions
- Removal of sediments (mud...)
- Dredging/ Removal of limnic sediments
- Estuarine and coastal dredging
- Siltation rate changes, dumping, depositing of dredged deposits
- Dumping, depositing of dredged deposits
- Other siltation rate changes
- Climate change
- Changes in abiotic conditions
- pH-changes
Habitat restoration potential
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
List of conservation and management needs
- Measures related to wetland, freshwater and coastal habitats
- Restoring/Improving water quality
- 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
- Measures related to special resouce use
- Regulating/Managing exploitation of natural resources on sea
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 | Decreasing |
| 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 | Unknown | Unknown | Unknown | There is insufficient quantitative data to make an accurate estimate of EOO and AOO. |
| EU28+ | Unknown | Unknown | There is insufficient quantitative data to make an accurate estimate of EOO and AOO. |
EOO = the area (km2) of the envelope around all occurrences of a habitat (calculated by a minimum convex polygon).
