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Plans | Habitats | Sabellaria spinulosa reefs

Habitat Action Plan

Sabellaria spinulosa reefs

Current Status

Physical and biological status

Sabellaria spinulosa reefs, JNCC Marine Nature Conservation Review (MNCR) biotope code CMX.SspiMx, comprise dense subtidal aggregations of this small, tube-building polychaete worm. Sabellaria spinulosa can act to stabilise cobble, pebble and gravel habitats, providing a consolidated habitat for epibenthic species. They are solid (albeit fragile), massive structures at least several centimetres thick, raised above the surrounding seabed, and persisting for many years. As such, they provide a biogenic habitat that allows many other associated species to become established. The S. spinulosa reef habitats of greatest nature conservation significance are those which occur on predominantly sediment or mixed sediment areas. These enable a range of epibenthic species with their associated fauna and a specialised 'crevice` infauna, which would not otherwise be found in the area, to become established. Studies have compared an area of S. spinulosa with other macrofaunal communities in the Bristol Channel and found that the former had a higher faunal diversity (more than 88 species) and higher annual production (dominated by suspension-feeders) than other benthic communities in the area.
S. spinulosa requires only a few key environmental factors for survival in UK waters. Most important seems to be a good supply of sand grains for tube building, put into suspension by strong water movement (either tidal currents or wave action). S. spinulosa also appears to be very tolerant of polluted conditions. The worms need some form of hard substratum to which their tubes will initially be attached, whether bedrock, boulders, artificial substrata, pebbles or shell fragments. However, the presence of extensive reefs in predominantly sediment areas indicates that, once an initial concretion of tubes has formed, additional worms may settle onto the colony enabling it to grow to considerable size without the need for additional 'anchorage` points. Published work has noted that the planktonic larvae are strongly stimulated to settle onto living or old colonies of S. spinulosa, although they will eventually (after two or three months in the plankton) settle onto any suitable substratum in the absence of other individuals.
Given its few key requirements, and its tolerance of poor water quality, S. spinulosa is naturally common around the British Isles. It is found in the subtidal and lower intertidal/sublittoral fringe with a wide distribution throughout the north-east Atlantic, especially in areas of turbid seawater with a high sediment load. Recent research in the Wash using remote video, identified very extensive areas of reef rising up to 60 cm above the seabed and almost continuously covering a linear extent of 300 m. However, in most parts of its geographical range S. spinulosa does not form reefs, but is solitary or in small groups encrusting pebbles, shell, kelp holdfasts and bedrock. It is often cryptic and easily overlooked in these habitats. Where conditions are favourable, much more extensive thin crusts can be formed, sometimes covering extensive areas of seabed. However, these crusts may be only seasonal features, being broken up during winter storms and quickly reforming through new settlement the following spring. There are extensive examples of this form of colony on the west Wales coast, particularly off the Lleyn Peninsula and Sarnau candidate Special Area of Conservation (cSAC) and the Berwickshire and North Northumberland Coast cSAC. These crusts are not considered to constitute true S. spinulosa reef habitats because of their ephemeral nature, which does not provide a stable biogenic habitat enabling associated species to become established in areas where they are otherwise absent.
The closely related Sabellaria alveolata has been recorded as living for up to nine years. It is possible that S. spinulosa is similarly long-lived. The examination of reefs in the Bristol Channel revealed that they possessed only a small number of young, derived from sources outside of the study area. The adults in the colony were not gravid during the study and grew very little. The age of a colony may greatly exceed the age of the oldest individuals present, as empty concretions of S. spinulosa sand tubes are frequently found and must be able to persist for some time in the marine environment. However, there have been no studies of the longevity of individual worms, or the longevity and stability of colonies or reefs.
Consideration of the present and historical status of this habitat in the Wadden Sea area is useful because it has been much better studied than in the UK. Large subtidal S. spinulosa reefs in the German Wadden Sea, which provided an important habitat for a wide range of associated species, have been completely lost since the 1920s. S. spinulosa now appears in the Red List of Macrofaunal Benthic Invertebrates of the Wadden Sea.

Links with other action plans

In this action plan and those for Sabellaria alveolata and sublittoral sands and gravels; emphasis is placed on damage that may be caused by physical disturbance. Sessile organisms in these habitats are vulnerable to damage resulting from fishing activity and aggregate extraction.

Current factors affecting the habitat

The greatest impact on this biogenic habitat is considered to be physical disturbance from fisheries activities. Dredging for oysters and mussels, trawling for shrimp or fin fish, net fishing and potting can all cause physical damage to erect S. spinulosa reef communities. The impact of the mobile gear breaks the reefs down into small chunks which no longer provide a habitat for the rich infauna and epifauna associated with this biotope. Research has attributed the loss of the large S. spinulosa reefs in the Wadden Sea to the long-term effects of fishing activity. It has also been noted that commercial fishermen sought out areas of S. spinulosa before trawling for pink shrimp Pandalus montagui, and appear to have destroyed the reefs along with their associated shrimp fishery in the process. A similar detrimental effect on S. spinulosa was reported during the 1950s in Morecambe Bay. Published work has also identified crustacean shellfisheries and potting, and molluscan shellfisheries, as the activities to which S. spinulosa accretions are most sensitive.
Aggregate dredging often takes place in areas of mixed sediment where S. spinulosa reefs may occur. For example, an Environmental Statement by Civil and Marine (1994) on a dredging licence for the outer Bristol Channel raised concern over the occurrence of some S. spinulosa reefs within the proposed licence area. Some dredged samples were comprised of up to 60% S. spinulosa by volume. The impacts of this activity on their long-term survival is unknown, but suspension of fine material during adjacent dredging activity is not considered likely to have detrimental effects on the habitat. A licence condition has therefore been stipulated that the operator, when dredging, avoids the reefs identified within the licensed zone. Aggregate extraction is not considered to be as significant a threat as commercial fisheries, provided that environmental assessments identify reefs, exclude licenced areas and/or establish 'refuge' zones, avoid other reef habitats while dredging, and carry out appropriate monitoring and biological study.
Pollution is listed as one of the major threats to S. spinulosa in the Wadden Sea. However, pollution was not identify as a significant problem (sludge dumping in Dublin Bay actually encouraged the establishment of Sabellaria) unless high sedimentation drastically changed the substratum. S. spinulosa reefs in the Wadden Sea, destroyed by fishing activities, have been replaced by beds of mussel Mytilus edulis and sand-dwelling amphipods Bathyporeia spp. This is partly attributed to an increase in coastal eutrophication, favouring Mytilus.
The risk to S. spinulosa from trawling and dredging has been considered high. Other research has assigned scores of moderately high to very high for damage, fragility, longevity and stability to Sabellaria accretions, but a low intolerance score (these species are considered to be tolerant to a moderate variety of environmental changes). Recovery was considered to be unlikely within ten years. Regeneration of this habitat is classified as 'difficult` (15-150 years) in the Wadden Sea Red List.

Current Action

Legal status

There is currently no statutory protection for known examples of this sublittoral habitat in the UK. The marine SACs list is incomplete with respect to biogenic reefs, although Sabellaria spinulosa reefs may represent important sub-features of other Annex I habitats for which a site was selected. None of the cSACs were selected specifically for biogenic reefs, although they may represent important sub-features of other Annex 1 habitats ('Sandbanks which are covered by seawater at all times'; 'Large shallow bays and inlets', and 'Estuaries'), for which a site was selected. Environmental assessments carried out prior to aggregate extraction operations could result in refusal of licences by the Department of the Environment, Transport and the Regions (DETR), or imposition of conditions to minimise dredging impacts.

Management, research and guidance

Two recent studies have provided a significant contribution towards the understanding of this habitat and the gaps in knowledge which require attention. The MNCR Database holds information on the occurrence of S. spinulosa around the UK coast, and examples of reef habitats may be identified during mapping surveys of both candidate and proposed marine SACs. Researchers monitoring aggregate extraction may hold unpublished data on persistence, growth and other biological characteristics.

Action plan objectives and targets

By 2004 maintain the extent and distribution of existing S. spinulosa reefs in the UK.
By 2004 maintain the quality of existing S. spinulosa reefs in the UK.
By 2004 establish and ensure necessary habitat conditions required for the re-establishment of S. spinulosa reef where formerly found, for example in the Essex Estuaries and Morecambe Bay.

Proposed actions with lead agencies

Policy and legislation

Exclude important examples of S. spinulosa reef from aggregate extraction licence areas. Attach detailed monitoring and research conditions to other licences. (ACTION: CCW, CEC, DETR, EHS, NE, MAFF, NAW, SE)
Ensure that all relevant SAC management schemes take account of the effects of dredging and trawling. (ACTION: All relevant authorities)

Site safeguard and management

Establish restrictions on use of mobile fishing gear within areas of known and former habitat where recovery is sought. (ACTION: DANI, MAFF, LAs, SE, SFCs)
Establish voluntary mechanisms outside SACs. (ACTION: CCW, NE, EHS, SFC, SNH)


By 2002 develop a code of practice to protect against damage from dredging and trawling. (ACTION: CCW, EHS, NE, MAFF, SE, SFCs, SNH)


Participate in initiatives to develop and strengthen measures for conservation of S. spinulosa reefs in Europe and elsewhere. (ACTION: DETR, JNCC)

Research and monitoring

Refine the MNCR list of characteristic species associated with S. spinulosa reefs, including commercial species (eg pink shrimp Pandalus montagui) and identify indicators of habitat quality. (ACTION: CCW, NE, JNCC, MAFF)
Investigate and assess the distribution, area and habitat quality of S. spinulosa reefs. (ACTION: CCW, EHS, NE, JNCC, SNH)
Investigate life cycles, recruitment and longevity of reefs and their associated fauna. Commission research on the interaction and competition between S. spinulosa and other filter feeders (eg Ophiothrix fragilis and Mytilus edulis). (ACTION: CCW, CEC, NE, MAFF, NERC, SNH)
Initiate biological monitoring programmes in aggregate dredged and undredged areas. (ACTION: CEC, MAFF)
Study the effect of towed fishing gear on S. spinulosa reefs, their potential for recovery and rates of recovery. (ACTION: CCW, EHS, NE, MAFF, NAW, NERC, SE, SNH)
By 2004, compile an inventory of areas which formerly supported S. spinulosa reefs, establish the necessary habitat conditions for re-establishment, and identify the highest priority sites for re-establishment. (ACTION: CCW, EHS, NE, JNCC, SNH)

Communications and publicity

Raise awareness of the importance of S. spinulosa reef habitats to marine biodiversity within the dredging and fishing industry. (ACTION: CCW, CEC, EHS, NE, MAFF, SE)
Publish an appropriate code of practice for commercial and recreational marine users. (ACTION: CCW, CEC, EHS, NE, MAFF, SE, SNH)


The successful implementation of this habitat action plan will have resource implications for both the public and private sectors. The data in the table overleaf provide an estimate of the current expenditure on the habitat and the likely additional resource costs. These additional costs are based on the annual average over 5 and 10 years. The total expenditure for these time periods is also given. Almost all the costs will relate to the public sector, although some costs (eg for research) will be met by the private sector/non-governmental organisations).
  Current expenditure 1st 5 yrs to 2004/2005 Next 10 yrs to 2014/2015
Current expenditure /£000/Yr      
Total average annual cost /£000/Yr   53.6 21.1
Total expenditure to 2005/£000   268.0  
Total expenditure 2005 to 2014/£000     211.0

Key references

Civil & Marine. 1994. Environmental Statement: Bristol Channel Outer Area 394 aggregate dredging license application.
Foster-Smith, R., Sotheran, I., & Walton, R. 1997. Broadscale mapping of habitats and biota of the sublittoral seabed of the Wash. Final report of the 1996 broadscale mapping project survey. A report to the Eastern Joint Sea Fisheries Committee and English Nature, Peterborough.
Fowler, S.L. 1989. Nature conservation implications of damage to the seabed by commercial fishing operations. Contract Survey Report No. 79, Nature Conservancy Council, Peterborough.
Holt, T.J., Rees, E.I., Hawkins, S.J., & Seed, R. 1998. Biogenic Reefs: An overview of dynamic and sensitivity characteristics for conservation management of Marine SACs. Scottish Association of Marine Sciences/UK Marine SACs Project, Oban, Scotland.
Mistakidis, M.N. 1956. Survey of the pink shrimp fishery in Morecambe Bay. Lancashire and Western Sea Fisheries Joint Committee.
Munroe, C. 1993. Sabellaria spinulosa: a review in relation to the proposed aggregate dredging site. Report from Marine Biological Surveys to Civil and Marine Ltd for the Bristol Channel Outer Dredging License Application Environmental Assessment.
Reise K. 1982. Long term changes in the macrobenthic invertebrate fauna of the Wadden Sea: are polychaetes about to take over? Netherlands Journal of Sea Research, 16 , 29-36.
Warren, P.J. & Sheldon, R.W. 1967. Feeding and migration patterns of the pink shrimp Pandalus montagui in the estuary of the River Crouch, England. Journal of Fisheries Research Canada, 24 , 569-580.
Wilson, D.P. 1971. Sabellaria colonies at Duckpool, North Cornwall, 1961-70. Journal of the Marine Biological Association UK, 51 , 509-580.

Local implementation

The following LBAPs are working on Sabellaria spinulosa reefs:

Dorset Biodiversity Initiative

Publication details

Originally published in: UK Biodiversity Group Tranche 2 Action Plans - Volume V: Maritime species and habitats (October 1999, Tranche 2, Vol V, p145)
© Joint Nature Conservation Committee 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010