Red List habitat classification > RL - Marine habitats > RLNEA - Atlantic > NEAA4.12 Sponge communities on Atlantic lower circalittoral rock

Sponge communities on Atlantic lower circalittoral rock

Quick facts

Red List habitat type code NEAA4.12
Threat status
Europe Data Deficient
EU Data Deficient
Relation to
Source European Red List habitat factsheet
European Red List of habitats reports
European Red List of habitats (Excel table)

Summary

This habitat type typically occurs on circalittoral rock (commonly  below 30m depth) in areas subject to negligible tidal streams. The sponge component is the most striking feature, and can be present in large aggregations. The sponges are important structure components; they contribute to bioerosion, consolidate sediment and stabilise habitats thereby reducing physical disturbance, and through aggressive competitive growth and seasonal retraction maintain space for new recruits and species thus maintaining biodiversity.

A species rich hydroid/bryozoan turf may develop in the understorey of this diverse sponge assemblage. Sponge fields also support various ophiuroids, which use the sponges as elevated perches. The prominent mobile species of the associated community consist mainly of decapod crustaceans, gastropod molluscs and echinoderms. A diverse 'cryptofauna' of nemerteans, polychaetes and amphipods also exists, living within and between the larger sessile organisms, acting as grazers, predators and detritivores. Fish  may also be present, but they are not considered characteristic members of the community. 

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 agreedindicators 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. Indicators of 'naturalness' have been described for this habitat and may be used to make some assessment of habitat quality. These are; community composition including the presence of older, larger individuals within the community, presence of intact (undamaged) fragile sponges and other fragile epifauna, low levels of silt, filter feeders unsmothered, no increases of silt tolerant species, and presence of typical species.

Characteristic species
For full habitat description, please download the habitat factsheet.

Threat status

Synthesis of Red List assessment

This habitat has a large EOO and AOO, and therefore qualifies as Least Concern under criterion B. However the habitat is assessed as Data Deficient both at the EU 28 and EU 28+ levels because of the lack of information on area and any trends in quantity and quality.
EU
Red List Category Red List Criteria
Data Deficient
Europe
Red List Category Red List Criteria
Data Deficient

Confidence in the assessment

low
Red List of habitat categories and criteria descriptions

Pressures and threats

  • Biological resource use other than agriculture & forestry
    • Fishing and harvesting aquatic resources
    • Professional passive fishing
    • Potting
    • Netting
    • Professional active fishing
    • Benthic or demersal trawling
    • Benthic dredging
    • Illegal taking/ removal of marine fauna
    • Removal for collection purposes
  • Climate change
    • Changes in biotic conditions
    • Migration of species (natural newcomers)

Habitat restoration potential

Little is known about the capacity of this habitat to recover when severely damaged however the presence of large, slow growing organisms may mean that full recovery from damage or loss of such individuals, could take many years. Warm shallow-water sponge species have shown rapid recovery from physical disturbance, yet it is thought that the slower growing, cold deep-water sponge species are much more susceptible to physical damage.
Little is known of the longevity and recruitment prospects for the sponges that characterise this habitat but evidence from monitoring studies at Lundy, England, suggests that growth of Axinella dissimilis (as Axinella polypoides) and Homaxinella subdola is no more than about 2 mm a year (the sponges grow to a height of up to about 300 mm) and that all branching sponges included in photographic monitoring over a period of four years exhibited very little or no growth in that time. Furthermore, no recruitment of sponges was observed. The predominance of erect sponges in this habitat is likely to mean that any decline in the occurrence of this habitat is likely to be permanent.

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

This habitat is present within some Marine Protected Areas and in zones where the use of bottom trawling in prohibited (e.g. on the Cantabrian Shelf). There are some long term monitoring sites (e.g. Isles of Scilly, UK), however no conservation measures that specifically target this habitat have been identified.

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

Distribution

For each habitat a distribution map was produced from a wide variety of sources indicating known and potential occurrences of the habitat in 10x10 km grids within Europe. Occurrences in grid cells were given in two classes: actual distribution from relatively reliable sources (surveys, expert knowledge), and potential distribution based on models or less reliable indicators. Please download the fact sheet to see the map.

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 Unknown Unknown
Celtic Seas
Greater North Sea
Macaronesia
Kattegat

Extent of Occurrence, Area of Occupancy and habitat area

Extent of Occurrence (EOO) (Km2) Area of Occupancy (AOO) Current estimated Total Area Comment
EU28 960,699 97 Unknown 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.
EU28+ >97 Unknown 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.
AOO = the area occupied by a habitat measured in number of 10x10 km grid cells.
EOO = the area (km2) of the envelope around all occurrences of a habitat (calculated by a minimum convex polygon).

Characteristic species

Not available

Vegetation types

Relation to vegetation types (syntaxa)

Not available

Other classifications

Not available
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