These plans are from the original UKBAP Tranches 1 and 2 (1995-1999)
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Plans | Habitats | Sabellaria alveolata reefs

Habitat Action Plan

Sabellaria alveolata reefs

Current Status

Physical and biological status

Sabellaria alveolata reefs, Marine Nature Conservation Review (MNCR) habitat code MLR.Salv, are formed by the honeycomb worm Sabellaria alveolata, a polychaete which constructs tubes in tightly packed masses with a distinctive honeycomb-like appearance. These reefs can be up to 30 or even 50 cm thick and take the form of hummocks, sheets or more massive formations. Reefs are mainly found on the bottom third of the shore, but may reach mean high water of neap tides and extend into the shallow subtidal in places. They do not seem to penetrate far into low salinity areas. Reefs form on a variety of hard substrata, from pebbles to bedrock, in areas with a good supply of suspended sand grains from which the animals form their tubes, and include areas of sediment when an attachment has been established. The larvae are strongly stimulated to settle by the presence of existing colonies or their dead remains. S. alveolata has a very variable recruitment and the cover in any one area may vary greatly over a number of years, although in the long term reefs tend mainly to be found on the same shores.
In Britain, S. alveolata reefs are found only on shores with strong to moderate wave action in the south and west, between Lyme Bay on the south coast of England and the Scottish coast of the Solway Firth. The reefs have also been found on parts of the Northern Ireland coast. The British Isles represent the northern extremity of the range in the north-east Atlantic, which extends south to Morocco. The reefs also occur in the Mediterranean.
Individual worms have a lifespan of typically three to five years, and possibly up to nine years, but reefs themselves may last longer as a result of further settlement of worms onto existing colonies. Typically in the first two years or so, after a heavy intertidal settlement, there are few associated species. Over time, seaweeds including fucoids, Palmaria palmata, Polysiphonia spp, Ceramium spp, Enteromorpha spp and Ulva lactuca, and animals including barnacles, dogwhelks, winkles, mussels and other bivalves such as Nucula nucleus, Sphenia binghami and Musculus discors, colonise the reef. Small polychaetes such as Fabricia stellaris, Golfingia spp and syllidae predators may occur within the colonies. Blennies, small crabs (Carcinus maenas) and other crustacea (such as Unicola crenatipalma) can be found within crevices. Older reefs may increase the biodiversity and stability of what would otherwise be sand abraded rocks and boulders. Sheet-like reefs may restrict drainage of the shore, creating rockpools where there would otherwise be none. Less is known about subtidal communities.
In Britain, S. alveolata forms well developed reefs over much of its range. The most numerous and extensive areas occur on the Cumbrian coast, particularly between the Morecambe Bay and the Solway Estuary and at Dubmill Point. Reefs are also found in Cardigan Bay and in the Bristol Channel, including the coasts of south Wales, north Devon, Somerset and Avon. Very extensive subtidal reefs occur in the Severn Estuary, and subtidal populations have also been reported in the Walney Channel (Morecambe Bay) and from Glassdrumman, Northern Ireland.
There is evidence of a significant contraction in range on the south coast of England over a period of at least 20 years until 1984. Declines have also been reported in the western part of the north Cornish coast, the upper parts of the Bristol Channel and in North Wales and the Dee Estuary. Causes have not been postulated and it is difficult to assess the true significance of these changes given the natural variability of the species. For example, S. alveolata reefs have recently developed off Heysham (in Morecambe Bay), dominating two hectares of boulder scar from where it had been absent for 30 years.

Links with other action plans

Reference should be made to the Sabellaria spinulosa reefs habitat action plan with particular regard to common actions for these habitats in the subtidal environment. Attention should also be given to the sublittoral sands and gravels habitat action plan, where emphasis is placed on the damage (through physical disturbance) that may be inflicted on sessile organisms by coastal development.

Current factors affecting the habitat

Sabellaria alveolata reefs are at the northern end of their range in Britain and are affected by extremely cold winters, after which they may die back for many years, particularly at higher shore levels.
By their nature, S. alveolata reefs occur in areas which are naturally subject to large scale changes in the amount of sand. They can tolerate burial for a period of days or even weeks, but prolonged burial will cause mortality.
S. alveolata reefs are potentially vulnerable to accumulations or losses of sand as a result of shoreline development, which is the major cause of loss in parts of Europe. These developments may have positive or negative effects depending on the nature of the changes.
Trampling damage by beach users and extraction of the worms for angling bait both occur, but on a limited and local scale. The former probably has the greater potential for damage, particularly in parts of Wales and south-west England, as leisure use of beaches continues to increase.
There is some evidence that competition for space with common mussels Mytilus edulis occurs, especially on boulder scars, but factors influencing this are unknown. Heavy settlement of mussels on S. alveolata reefs has been suspected of causing short term destabilisation and loss of habitat.
S. alveolata is naturally subject to very variable recruitment, but the factors influencing this are not fully understood. Lack of larval supply and wave exposure is thought to be an important factor in the general absence of reefs on Anglesey and near to major peninsulas such as south-west Cornwall, Pembrokeshire and the Lleyn Peninsula.

Current Action

Legal status

Intertidalprotection for S. alveolata reefs can be achieved through SSSI designation. S. alveolata reefs also occur as sub-features of non-reef Annex 1 habitats (eg intertidal mudflats and sandflats) under the Habitats Directive and are present in a number of candidate Special Areas of Conservation (cSACs), including the Solway Firth, Lleyn Peninsula and the Sarnau, Cardigan Bay and Morecambe Bay. However, many examples of S. alveolata reefs lie outside these areas.
Discharges to the sea are controlled by a number of EC Directives, including the Dangerous Substances, Shellfish (Waters), Integrated Pollution Control, Urban Waste Water Treatment, and Bathing Waters Directives. The forthcoming Water Framework Directive will also be relevant. The Oslo and Paris Convention (OSPAR) and North Sea Conference declarations are also important. These commitments provide powers to regulate discharges to the sea and have set targets and quality standards to marine waters. An extensive set of standards covering many metals, pesticides and other toxic, persistent and bioaccumulative substances, and nutrients have been set under UK legislation.

Management, research and guidance

There is, presently, negligible active research on S. alveolata within Britain, although small scale surveys of recently developed reefs off Heysham in Morecambe Bay have been carried out. A report summarising the dynamics and sensitivity of biogenic reefs, including S. alveolata reefs, was recently commissioned for the UK Marine SAC Project. Aerial photographs have also been used by the conservation agencies to map intertidal S. alveolata reefs and the MNCR Database holds information on the occurrence of S. alveolata habitats around the UK coast. It is probable that subtidal reefs in the Severn Estuary proposed SAC will be monitored by CCW and NE as part of the management scheme for that site.

Action plan objectives and targets

Maintain the extent of S. alveolata reef habitats.
Maintain the quality of S. alveolata reef habitats.
Within 15 years, attempt to re-establish S. alveolata reefs in five areas where they were formerly present.

Proposed actions with lead agencies

Policy and legislation

Promote planning policies that seek to direct development away from sites of marine natural heritage importance. (ACTION: DETR, EHS, NAW, SE)

Site safeguard and management

Ensure that when considering the need for, and scope of, Environmental Impact Assessments, the needs of S. alveolata, (including sediment supply), are fully taken into account. (ACTION: CCW, EA, EHS, NE, LAs, SE)
In candidate and proposed SACs with S. alveolata reefs, develop site specific management and protection, including designated monitoring and research areas, which ensure conditions for survival and persistence. (ACTION: CCW, EHS, NE, SNH)
Consider the designation of further SSSIs and ASSIs or the establishment of voluntary refuge areas for S. alveolata reefs outside designated sites. (ACTION: CCW, EHS, NE, SNH)


Raise awareness of the scarcity and fragility of S. alveolata reefs with conservation officers and the public by targeted publicity (posters and leaflets to be produced by 2003). Ensure that this habitat is included in 'Beach/Shore' codes of practice. Effort should be made to involve officers of country agencies, wardens of voluntary reserves and heritage coast officers in survey work. (ACTION: CCW, EHS, NE, SNH)


Exchange information with experts in France, Ireland, Spain and Portugal on habitat distribution, role in coastal ecosystems and impacts of development. This would greatly help decision making in the UK. (ACTION: JNCC)

Research and monitoring

Establish by 2003 the extent and quality of significant areas of S. alveolata reef habitat in the UK. The study should compare the present extent of reefs with the last extensive intertidal survey in the early 1980s. There is a need especially to include shallow subtidal areas as these have previously been little studied. (ACTION: CCW, EHS, NE, NERC, SNH)
Commission research on growth rates, longevity, and persistence of both individual worms and associated reef dynamics, under a variety of environmental conditions including the edges of geographic ranges. Establish by 2003 the necessary habitat conditions for the re establishment of S. alveolata reefs within former areas. Research on subtidal reefs should be carried out as a priority since almost nothing is known about these. (ACTION: CCW, EHS, NE, NERC, SNH)
Undertake research on recruitment processes, including sources of larvae and exchange between populations using modern molecular genetics techniques. (ACTION: NERC)
Undertake surveys of damage to reefs in areas with different levels of recreational activity. Quantify recreational damage in field experiments (at non sensitive sites) to measure recovery potential. (ACTION: CCW, EHS, NERC, SNH)
Investigate the role of S. alveolata reefs in habitat modification including stabilisation of cobble boulder bottoms. (ACTION: CCW, EHS, NE, NERC, SNH)
Compile a simple leaflet with an attached record sheet to be returned to a lead agency in order to both heighten awareness and provide valuable distributional data.  (ACTION: CCW, EHS, NE, SNH)

Communications and publicity

Many sites in south-west England and Wales are in areas of high tourist activity. Display material strategically placed in car parks and foreshore access points could be used to highlight the natural history of this interesting habitat to casual beach users. Advice should also be given to discourage trampling. (ACTION: CCW, NE)


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   62.8 28.4
Total expenditure to 2005/£000   314  
Total expenditure 2005 to 2014/£000     284

Key references

Connor, D.W., Brazier, D.P., Hill, T.O., Holt, R.H.F., Northen, K.O. & Sanderson, W.G. 1997. Marine Nature Conservation Review: Marine biotope classification for Britain and Ireland. Volume 2. Sublittoral biotopes. Version 97.06. Report No.230, Joint Nature Conservation Committee, Peterborough.
Covey, R. 1998. Marine Nature Conservation Review Sector 11. Liverpool Bay and the Solway Firth: area summaries. Coasts and seas of the United Kingdom, MNCR series, Joint Nature Conservation Committee, Peterborough.
Crisp, D.J. 1964. The effects of the severe winter of 1962-63 on marine life in Britain. Journal of Animal Ecology, 32-33 , 165-211.
Cunningham, P.N., Hawkins, S.J., Jones, H.D. & Burrows, M.T. 1984. The biogeography and ecology of Sabellaria alveolata. CSD report No.535, Nature Conservancy Council.
Gruet, Y. 1986. Spatio-temporal changes of sabellarian reefs built by the sedentary polychaete Sabellaria alveolata (Linne), P.s.z.n. I. Marine Ecology, 7 , 303-319.
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 Science/UK Marine SACs Project, Oban, Scotland.
Perkins, E.J. 1988. Fourteenth report to the Cumbria Sea-Fisheries Committee. Solway Firth survey - 1st July 1987 to 30th June 1988. Solway Marine Investigations, Maryport, Cumbria.
Wilson, D.P. 1968. Some aspects of the development of eggs and larvae of Sabellaria alveolata (L.). Journal of the Marine Biological Association UK, 48 , 367-386.
Wilson, D.P. 1971. Sabellaria colonies at Duckpool, North Cornwall, 1961-1970. Journal of the Marine Biological Association UK, 51 , 509-580.

Local implementation

The following LBAPs are working on Sabellaria alveolata reefs:

A local Biodiversity Action Plan for Swansea Teignbridge BAP West Somerset Biodiversity Action Plan West Somerset Biodiversity Action Plan Dorset Biodiversity Initiative Cornwall’s Biodiversity vol 1, 2 and 3 Cumbria Biodiversity Action Plan

Publication details

Originally published in: UK Biodiversity Group Tranche 2 Action Plans - Volume V: Maritime species and habitats (October 1999, Tranche 2, Vol V, p125)
© Joint Nature Conservation Committee 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010