Sabellaria Spinulosa Reefs

QUALITY STATUS REPORT 2010 Case Reports for the OSPAR List of threatened and/or declining species and habitats – Update cirratulids together with the bivalves Abra alba Sabellaria spinulosa and Nucula spp. and tube-building amphipods such as Ampelisca spp. Epifauna comprise reefs calcareous tubeworms, pycnogonids, hermit crabs, amphipods, hydroids, bryozoans, EUNIS Code: A4.22 and A5.611 sponges and ascidians. The characteristics of National Marine Habitat Classification for UK & the reefs are linked to the density of Ireland code: SS.SBR.PoR.SspiMx and aggregation and these are known to vary CR.MCR.CSab 2 widely e.g. 120/m in Belfast Lough, Northern Ireland and more than 4500/in the Wash on the east coast of England (in Hednrick & Foster-Smith, 2006). S.spinulosa reefs are often found in areas with quite high levels of natural sediment disturbance; in some areas of reef, individual clumps of Sabellaria may periodically break down and rebuild following storm events. S.spinulosa reefs have been recorded from all European coasts except the Baltic Sea, Skagerrak and Kattegat. Areas of dead Sabellaria reef indicate the site supported reef habitat in the past and should ©D Connor JNCC be reported as this habitat type S.spinulosa is a small, tube-building polychaete worm found in the subtidal and Geographical extent lower intertidal/sublittoral fringe. In most parts of its geographic range it does not form reefs OSPAR Regions; The OSPAR List indicates but is solitary or found in small groups, S.spinulosa reefs occur in all OSPAR regions encrusting pebbles, shell, kelp holdfasts and but there is very limited evidence of their bedrock. When conditions are favourable occurrence in Regions I and V. dense aggregations may be found, forming Biogeographic zones: Warm-temperate pelagic reefs up to about 60cms high and extending waters, Lusitanean (Cold/Warm), Lusitanean- over several hectares; these are often raised boreal, Cold-temperate pelagic waters, Boreal- above the surrounding seabed. Reefs may lusitanean, Boreal, Norwegian Coast persist in an area for many years although (Finnmark), Norwegian Coast individual clumps may regularly form and (Westnorwegian), Norwegian Coast disintegrate (Jackson & Hiscock, 2003; Jones (Skagerrak) et al., 2000). Regions specified for decline and/or threat: II and III. Definition for habitat mapping The tube-building polychaete Sabellaria S.spinulosa reefs are known from all European spinulosa can form dense aggregations on coasts, except the Baltic and the waters of the mixed substrata and on rocky habitats. In Kattegat and Skagerrak, but are typically mixed substrata habitats, comprised variously limited to areas with very high levels of of sand, gravel, pebble and cobble, the suspended sediment. In the UK aggregations Sabellaria covers 30% or more of the substrata of S.spinulosa are reported to occur at a and needs to be sufficiently thick and number of locations around the British Isles persistent to support an associated epibiota (OSPAR Regions II and III), although there are community which is distinct from surrounding few records for Scottish waters. Not all of habitats. On rocky habitats of bedrock, boulder these aggregations could be described as and cobble, the Sabellaria covers 50% or more “reefs”, for instance where the species may of the rock and may form a crust or be thicker only form superficial crusts on mixed substrata. in structure. In some areas, these two On the German coast, intertidal and subtidal variations of reef type may grade into each reefs have been reported from the Wadden other. Sabellaria reefs have been recorded in Sea (OSPAR Region II) (Berghahn & Vorberg, depths between 10-50m BCD or more. The 1993) and from the southern North Sea where reef infauna typically comprises polychaete Linke (1951) reported reefs up to 60 cm thick, species such as Protodorvillea kefersteini, 8m wide and 60m long. S.spinulosa has also Scoloplos armiger, Harmothoe spp., been reported from the French coast, but Mediomastus fragilis, Lanice conchilega and without precise locations (Holt et al., 1998). 1 QUALITY STATUS REPORT 2010 Case Reports for the OSPAR List of threatened and/or declining species and habitats – Update the Wash and the Thames (Warren & Sheldon 1967). In the western North Sea a report Application of the Texel-Faial criteria comparing records from 1986 and 2000 Nomination of Sabellaria spinulosa reefs to be suggest an increase in distribution and placed on the OSPAR list cited sensitivity, densities in the western North Sea (ICES, rarity, ecological significance and decline, with 2007). information also provided on threat. The nomination was for all OSPAR regions but this Rarity has been modified in light of ICES advice and True stable reefs, as opposed to crusts of the habitat is now nominated for OSPAR S.spinulosa, are believed to be rare or have a Regions II & III as this is where most very restricted distribution (Holt et al., 1998). information is available. Sensitivity Decline The findings from many studies on the Subtidal S.spinulosa reefs are reported to have sensitivity of S.spinulosa have been brought been lost in at least five areas of the north east together in reviews by Holt et al (1998), Jones Atlantic (Jones et al., 2000). et al (2000) and Jackson & Hiscock (2003) and can be found on the MarLIN website Large subtidal S.spinulosa reefs were common www.marlin.ac.uk. The highest sensitivity is to along the slopes of the northern tidal inlets of substratum loss and displacement as the the German Wadden Sea in the 1920s worms are fixed to the substratum and cannot (Hagmeier & Kändler, 1927) but have been reattach once dislodged, or rebuild their tubes largely lost since that time. Riesen & Reise if removed from them. Recruitment rates are (1982) reported that extensive subtidal high however and recovery could be quite S.spinulosa reefs were lost from the Lister Ley, rapid as this species is often one of the first to island of Sylt, between 1924 and 1982 and settle on newly exposed surfaces. Reise & Schubert (1987) reported similar losses from the Norderau area. Only three S.spinulosa does not appear to be particularly living reefs were found during surveys in the sensitive to changes in water quality (Holt et early 1990’s compared to 24 during the 19th al., 1998), but is both sensitive and vulnerable century (Figure A).In the late 1990’s, samples to physical damage. It is probably tolerant to taken from the subtidal reefs in the German smothering in the short term although this will Wadden Sea consisted largely of compact affect feeding and growth and may interfere lumps of empty tubes. In 2000, one of these with reproduction depending on the timing. reefs had diminished drastically in extent with S.spinulosa appears to be very tolerant of the remainder in poor condition although water quality variation, but is potentially dredge samples were occupied by many tiny vulnerable to the short-term and localized tubes with living worms inside. The third reef effects of mineral extraction and the effects of which had covered about 18ha could no longer oil dispersants on the larvae. Overall, however, be detected when repeat surveys were carried it has been concluded that S.spinulosa out in 2002, seemed unlikely to show any special sensitivity to chemical contaminants (Jackson & Hiscock, Figure A. Changing occurrences of 2003). S.spinulosa reefs in the Wadden Sea (Wadden Sea Secretariat, 2005) Well-developed, more stable reefs seem to be very scarce, and this apparent rarity suggests that an unusual set of environmental factors and/or circumstances is required for their formation. It might, therefore, be expected that they would display sensitivity to some factor or factors, but Jones et al., (2000) report there is little information from which to gain any insight into this Ecological significance S.spinulosa reefs can provide a biogenic habitat that allows many other associated species to become established and acts to stabilize cobble, pebble and gravel habitats. In the UK there are reports of reefs being lost They contain a more diverse fauna with in Morecambe Bay (Taylor & Parker, 1993), 2 QUALITY STATUS REPORT 2010 Case Reports for the OSPAR List of threatened and/or declining species and habitats – Update sometimes more than twice as many species better knowledge of the natural variation in and almost three times as many individuals extent, density and population structure of than nearby areas where S.spinulosa is absent reefs, is also required (Jackson & Hiscock, (NRA, 1994). The reefs are of particular nature 2003). conservation significance when they occur on sediment or mixed substrata areas as they Changes in relation to natural variability enable a range of other species to occur that Natural variability will play a part in changes in would not otherwise be found in such areas. the extent of this habitat type. S.spinulosa occurs in high densities on subtidal gravels Threat that are likely to be disturbed every year or The greatest impact on this biogenic habitat is perhaps once every few years due to storms. considered to be physical disturbance. Where it exists as loose crusts, death may Dredging, trawling, net fishing and potting can occur through break-up due to wave action. all cause physical damage to erect reef Increased wave action may also mobilize the communities (Riesen & Riese, 1982) although pebble and gravel substrata on which studies by Vorberg (2000) on a similar species S.spinulosa often occurs, resulting in abrasion (S.alveolata) indicated only minor damage to and mortality. High levels of recruitment mean tubes from shrimp fisheries and rapid recovery. that recovery could be quite rapid, say within a Vorberg (2000) has also suggested that shrimp year but timescales for the re-establishment of vessels used around the mid-20th century reefs are not clear (Jackson & Hiscock, 2003).

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