Atlantic upper circalittoral mixed sediments
|Red List habitat type||code NEAA5.44|
|Source||European Red List habitat factsheet|
|European Red List of habitats reports|
|European Red List of habitats (Excel table)|
This habitat comprises mixed (heterogeneous) sediment in the circalittoral zone (generally below 15-20 m). These include areas of well mixed muddy gravelly sands, or very poorly sorted mosaics of shell, cobbles and pebbles, embedded in, or lying upon mud, sand, or gravel. It is fully saline with tidal streams ranging from moderately strong (1-3kn) to negligible.
A wide range of infaunal polychaetes, bivalves, echinoderms and burrowing anemones, are often present in this habitat and the hard substrata (shells and stones) on the surface enables epifaunal species to become established, particularly hydroids. The combination of epifauna and infauna can lead to species-rich communities.
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 mayface; 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 overtime.
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.
Synthesis of Red List assessment
Most sedimentary benthic systems on the continental shelf of Europe have been modified by fishing activities, particularly bottom trawls and dredging, in the last 100 years and this habitat remains under fishing pressure. Disturbance of the substratum due to intensive fishing activities using bottom trawls or dredges can damage or modify infaunal communities, with burrowing echinoderms and bivalves being particularly vulnerable and therefore affect habitat quality. Data for a single year (2013/2014) has revealed that just over 50% of this habitat in the North Sea and Celtic Sea was subject to fishing pressure by bottom otter, beam and mid-water trawls.Given that this is based on a single year of data, and that this type ofpressure has been taking place for decades, it is likely to be an underestimate of the total area of this habitat which has been subject to such pressure. Cumulative impacts are therefore also likely to have occurred.
Expert opinion is that there has been a substantial reduction in quality of this habitat, most likely an intermediate decline affecting more than 50% of its extent although it is clear that in some locations there has also been a severe decline. The severity will depend on factors such as the intensity and frequency of disturbance. This habitat has therefore been assessed as Vulnerable for both the EU 28 and EU 28+ because of both past and likely continuing declines in quality.
|Red List Category||Red List Criteria|
|Red List Category||Red List Criteria|
Confidence in the assessment
Pressures and threats
- Biological resource use other than agriculture & forestry
- Fishing and harvesting aquatic resources
- Professional active fishing
- Benthic or demersal trawling
- Benthic dredging
- Natural System modifications
- Human induced changes in hydraulic conditions
- Modification of hydrographic functioning, general
- Modification of water flow (tidal & marine currents)
- Alteration of sea-floor/ Water body morphology
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 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
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)|
|Bay of Biscay and the Iberian Coast||Present||Unknown||Decreasing||Unknown|
|Greater North 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||4,978,767||1,801||>15,885||The area estimate for this habitat has been derived from a synthesis of EUNIS seabed habitat geospatial information for the European Seas, but is recognised as being an underestimate.|
|EU28+||>1,801||>15,885||EOO and AOO have been calculated on the available data. Although this data set is known to be incomplete the figures exceed the thresholds for threatened status.|
EOO = the area (km2) of the envelope around all occurrences of a habitat (calculated by a minimum convex polygon).
|Species scientific name||English common name||Species group|