Infaunal communities in Baltic infralittoral sand - bivalves
Quick facts
| Red List habitat type | code BAL31 |
|---|---|
| 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 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. There is a lack of macrovegetation or epibenthic macrofauna but infaunal bivalves make up at least 10% of the biomass. The habitat is present in areas of high energy associated with wave action or currents.
Six associated biotopes with different dominant species (at least 50% of the biomass of macrofauna) have been identified. Some have a restricted distribution in the Baltic. For example AB.J3L10 ‘Baltic aphotic sand dominated by multiple infaunal bivalve species: Macoma calcarea, Mya truncata, Astarte spp., Spisula spp.’ is only found at high salinities (> 18 psu) as all characteristic bivalves species are eumarine and do not tolerate lower salinities. The characteristic trait of the biotope is high species diversity. and it is encountered in the south-western Baltic Sea, from the Kiel bight to Isle of Fehmarn, and might occasionally occur from Mecklenburg Bight to Darss Sill. Where the substrate is well sorted medium to coarse sand, the large variety of interstitial space, may be inhabited by species of specialised fauna, such as the polychaetes Ophelia limacina, O. rathkei and Travisia forbesii. This fauna is restricted to the Belt Sea (sandbanks) and parts of the ‘submerged belt’ of the Arkona Basin.
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 determinedand applied on a location-specific basis. Diversity, abundance and biomass of fauna are potential indicators of quality.
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. HELCOM (2013) assessed the four associated biotopes AA.J3L1, AA.J3L2, AA.J3L4 and AA.J3L9 as Least Concern (A1) and AA.J3L3, AA.J3L10 and AA.J3L11 as Near Threatened (A1). Current expert opinion is that this habitat should be assessed as Near Threatened (A1) for both the EU 28 and EU 28+ because of recent and predicted future declines.
| 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
- Transportation and service corridors
- Shipping lanes, ports, marine constructions
- 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
- Siltation rate changes, dumping, depositing of dredged deposits
- Dumping, depositing of dredged deposits
- Other siltation rate changes
Habitat restoration potential
Trends in extent |
|
Average current trend in quantity |
|
Decreasing  |
Decreasing |
| EU28 | EU28+ |
Trends in quality |
|
Average current trend in quality |
|
| Decreasing |
Decreasing |
| 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
- Legal protection of habitats and species
- 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 | Decreasing | 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 | Unknown | Unknown | This habitat is present in all the Baltic sub-basins however there is insufficient information for accurate calculation of EOO and AOO. |
| EU28+ | Unknown | Unknown | This habitat is present in all the Baltic sub-basins however there is insufficient information for accurate calculation of EOO and AOO. |
EOO = the area (km2) of the envelope around all occurrences of a habitat (calculated by a minimum convex polygon).
