Serpulid aggregations

06-11-2008
Researched byJacqueline Hill & Catherine Wilding Refereed byDr David Hughes
EUNIS CodeA5.613 EUNIS NameSerpula vermicularis reefs on very sheltered circalittoral muddy sand

Summary

UK and Ireland classification

EUNIS 2008A5.613Serpula vermicularis reefs on very sheltered circalittoral muddy sand
EUNIS 2006A5.613Serpula vermicularis reefs on very sheltered circalittoral muddy sand
JNCC 2004SS.SBR.PoR.SerSerpulid aggregations
1997 BiotopeSS.CMS._.SerSerpula vermicularis reefs on very sheltered circalittoral muddy sand

Description

Large clumps ('mini reefs') of the calcareous tubes of Serpula vermicularis, typically attached to stones on muddy sediment in very sheltered conditions in sea lochs. A rich associated biota attached to the calcareous tube may include the sponge Esperiopsis fucorum, thin encrusting sponges, the ascidians Ascidiella aspersa, Pyura microcosmus and Diplosoma listerianum and fine hydroids such as Halopteris catharina. In shallow water dense Phycodrys rubens may grow on the reefs. Reefs from Loch Creran have been recently studied (Moore, 1996; Poloczanska et al., 2004). The only other known site in UK for these reefs was Loch Sween, but living reefs are no longer found there (Hughes et al., 2008). Otherwise only known from Salt Lake, Clifden and Killary Harbour, Co. Galway, Ireland. (Information adapted from the Marine Biotope Classification for Britain and Ireland, Version 97.06: Connor et al., 1997a, b).

Recorded distribution in Britain and Ireland

In Britain living Serpula vermicularis reefs are known from Loch Creran in Scotland. The only other known sites in Britain and Ireland for these reefs are at locations in County Galway. Reefs were reported from Loch Sween in Scotland in the 1980s, but these are now no longer living (Hughes et al., 2008). A large aggregation from the Hamoaze, Tamar Estuary, Plymouth was reported in the Plymouth Marine Fauna (MBA, 1957).

Depth range

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Additional information

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Habitat review

Ecology

Ecological and functional relationships

  • Serpula vermicularis normally occurs as individuals encrusted on hard surfaces. A tendency to form aggregations in certain conditions is reported but true reefs have an extremely limited distribution. It has been suggested that dense aggregations of Serpula vermicularis tubes only occur in enclosed and sheltered locations, where dispersal of larvae may be limited and where a suitable substratum is present. The hypothesis that reef formation occurs in Loch Creran due to limited larval dispersal is not currently backed up by any evidence. Loch Creran actually has quite a high flushing rate (Hughes pers. comm.) and there are many far more restricted sites in the area with no reef development. It is also questionable whether lack of suitable substratum is a factor leading to reef development. There are extensive areas of bedrock outcropping from the floor of Loch Creran but these typically support very limited and localised reef growth. Further, Chapman et al. (2007) suggest that the lower depth limit of reefs is not set by shortage of available substrata. The formation of reefs therefore is likely to be due to a complex interaction of many factors.
  • In Loch Creran individual reefs are reported to reach a height of about 75 cm and 1 m across, although adjacent reefs may coalesce to form larger reefs up to 3 m across (Moore, 1996). Bosence (1979b) described reefs up to 2m in height and 1m across from Ardbear Lough but suggested that aggregated reefs could extend for several hundred metres.
  • Serpula vermicularis requires a hard substratum on which to construct its tube. The most common substratum for settlement is bivalve shells. In Loch Creran it was particularly common on shells of Pecten, Aequipecten and Modiolus. Reefs form predominantly in areas where there is suitable substratum scattered throughout a muddy or muddy sand bottom. In this way, previously bare substratum can support dense aggregations of worms and a high diversity of associated species.
  • The structure of Serpula vermicularis reefs is quite open, increasing surface and space for colonization, as well as for food and refuge, for an abundant and varied animal community. The rich associated fauna of organisms includes sessile organisms such as ascidians, hydroids, bivalves and other polychaete worms such as Pomatoceros triqueter and Sabella pavonina. There is also a mobile component of the associated macrofauna which is rich in amphipods, and also includes fish, crabs, whelks and echinoderms that use the reefs for feeding, refuge and egg-laying (Moore et al., 1998b; Poloczanska et al., 2004). The open structure appears to be related to the regular spacing of the apertures of the tubes at 10-15 mm apart which gives enough space for the expansion of the branchial crowns during feeding (Bosence, 1979b).
  • Predation of Serpula vermicularis by several species has been described by Bosence (1979b) although the importance of the species as a food source is unknown. The wrasse Ctenolabrus rupestris and Crenilabrus melops were frequently seen biting serpulid tubes and extracting the worms. The starfish Asterias rubens was frequently seen with its stomach everted down the serpulid tubes. Bosence (1979b) also observed the urchins Echinus esculentus and Psammechinus miliaris feeding on serpulid tubes but thought it unlikely that they were feeding directly on the worms, which can withdraw into their tubes very rapidly, and were more likely to be eating the epifauna and epiflora on the tubes. Predation of Serpula vermicularis by Cancer pagurus, Carcinus maenas, Asterias rubens and Ctenolabrus rupestris was observed in Salt Lake, Ardbear Lough (Minchin, 1987). However, long term video monitoring of reefs in Loch Creran revealed very few instances of attempted predation on the worms (Poloczanska et al., 2004).

Seasonal and longer term change

The growth of Serpula vermicularis reefs may take many years so the major change over time is likely to be an increase in size of the reef. However, as growth of the reef proceeds, the old base is weakened by biological erosion by boring sponges and algae, and biting by fish and echinoderms. Segments of the reef then break off and provide new areas for larval settlement and this is the main way in which a reef growing from an original rocky substratum can extend outwards to cover areas of soft substratum (Bosence, 1979b). There may be seasonal changes in abundance of other species, such as hydroids, which often have life spans less than a year, and due to periodic recruitment of larvae.

Habitat structure and complexity

The reef habitat created by aggregated Serpula vermicularis tubes can be up to 2m high (Bosence, 1979b). Initial growth is encrusting but after that the worms grow away from the substratum in a sinuous fashion, sometimes becoming intertwined and the reefs develop as new worms are added to old tubes. The reef is a structurally complex habitat as the open form of the aggregated tubes provides a large surface area and many spaces which supports a high diversity of sessile and mobile macrofauna. In Loch Creran, Scotland reefs were found growing in bedrock, boulders, stones, shells and man-made substrata (Moore et al., 1998b). Large reefs were only rarely found growing on rock.

Productivity

The community is predominantly faunal so productivity in the biotope is largely secondary. Red algae such as Phycodrys rubens and encrusting corallines are present in the biotope, although not in very high abundance and so levels of primary production are not likely to be high. Although no information was found regarding the diet of Serpula vermicularis, analysis of digestive enzymes suggests that quite large detrital particles may form an important part of the diet (Michel & De Villez, 1978). Several of the other species in the biotope, such as the ascidians and other polychaetes, are also suspension feeders. Phytoplankton, supplemented by non-living detritus, is likely to be the main food source for all these species (Hughes, pers. comm.). Secondary production could be substantial in large reefs.

Recruitment processes

  • In the habitats in which this biotope is found, where water movement and exchange with coastal waters is limited, recruitment from local populations is particularly important because of the reduced supply of planktonic larvae from outside the system.
  • In Loch Creran, larval settlement occurs predominantly from mid-June to mid October, peaking in late August-early September (Chapman et al., 2007). The length of the planktonic stage is not known but comparison with other serpulids suggests it would probably be between 6 days and 2 months. However, settling time may vary depending on salinity or food availability, and delayed settling may reduce discrimination of substrata for settlement.
  • Reef development occurs by repeated settlement of larvae on the tubes of adults however evidence suggests that the larvae are not attracted to settle on adult tubes in preference to substratum. Experiments in Loch Creran showed that Serpula vermicularis larvae settled on slate in preference to scallop shell. There was no evidence of enhanced recruitment to occupied of unoccupied adult tubes, suggesting that gregarious attraction is unlikely to be a factor causing reef formation (Chapman et al., 2007).
  • Recruitment of sessile organisms in the biotope, such as sponges, ascidians and hydroids, is almost entirely from planktonic sources. Some species have larvae that can disperse widely and these may arrive from distant locations. Others, particularly the hydroids and some ascidians have short lived planktonic larvae so dispersal distances are short and recruitment will largely be from local populations.
  • Recruitment of the mobile predators and grazers may be through immigration of adults or via a larval dispersal phase. Mobile species such as decapod crustaceans, echinoderms and fish will settle from planktonic stages or migrate into the biotope.
  • Red algae have non flagellate, and non-motile spores that stick on contact with the substratum. Norton (1992) noted that algal spore dispersal is probably determined by currents and turbulent deposition. However, red algae produce large numbers of spores that may settle close to the adult especially where currents are reduced such as in sheltered locations.

Time for community to reach maturity

Although the growth rates of individual Serpula vermicularis worms are relatively high (Bosence, 1979b), showing an average linear rate of 33mm/year for adult tubes (Hughes et al., 2008), it is likely that reefs will take many years to develop. The reef develops upwards and outwards as larvae settle on to the tubes of existing worms and so it may take many periods of recruitment for reefs to become large. Many other species in the biotope, such as ascidians, hydroids and bryozoans exhibit annual recruitment and many are short lived so populations are likely to reach maturity rapidly. There are some slow growing species, such as encrusting coralline algae, which take longer to achieve significant coverage. Species diversity within the reef is likely to increase with time. However, the time to maturity of the biotope will depend on the time for reef development which is likely to be many years.

Additional information

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Preferences & Distribution

Recorded distribution in Britain and IrelandIn Britain living Serpula vermicularis reefs are known from Loch Creran in Scotland. The only other known sites in Britain and Ireland for these reefs are at locations in County Galway. Reefs were reported from Loch Sween in Scotland in the 1980s, but these are now no longer living (Hughes et al., 2008). A large aggregation from the Hamoaze, Tamar Estuary, Plymouth was reported in the Plymouth Marine Fauna (MBA, 1957).

Habitat preferences

Depth Range
Water clarity preferences
Limiting Nutrients Not relevant
Salinity
Physiographic
Biological Zone
Substratum
Tidal
Wave
Other preferences

Additional Information

No text entered

Species composition

Species found especially in this biotope

Rare or scarce species associated with this biotope

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Additional information

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Sensitivity reviewHow is sensitivity assessed?

Explanation

Serpula vermicularis is the only species selected to represent the sensitivity of the biotope. Although the biotope has a very high species diversity no other species are included because the individual species present may vary and the loss of these species is not likely to affect the function and existence of the biotope. Although the selected 'indicative species' are particularly important in undertaking the assessment because they have been subject to detailed research, account is taken of knowledge of the biology of all characterizing species in the biotope when undertaking an assessment of sensitivity of this biotope.

Species indicative of sensitivity

Community ImportanceSpecies nameCommon Name
Key structuralSerpula vermicularisSerpulid tube worm

Physical Pressures

 IntoleranceRecoverabilitySensitivitySpecies RichnessEvidence/Confidence
High Very low / none Very High Major decline Moderate
Serpula vermicularis forms reefs by attachment to the substratum and so will be highly intolerant of removal of the substratum. The sessile epifauna associated with the reefs, such as ascidian, hydroids and bryozoans, will also be removed. Some mobile species, such as fish and crabs, may be able to escape, but many are slow moving and will also be lost if substratum is removed. Intolerance of the biotope is therefore, high. Recovery from complete loss of reefs is likely to take a very long time, if at all, and a rank of very low is reported, resulting in a very high sensitivity rating - see additional information for full rationale.
Intermediate High Low Decline Moderate
Serpula vermicularis is permanently attached to the substratum by a calcareous tube which in aggregating reef forming individuals extends above the substratum as new worms are added to old tubes. For example, in Loch Creran individual reefs are reported to reach a height of about 75cm (Moore, 1996). The reef structure is also very open, creating cracks and crevices where sediment could collect. Therefore, many individuals of Serpula vermicularis, and the associated fauna of sponges, ascidians and hydroids, may avoid 5cm of smothering material. Some of the mobile species in the biotope may be able to avoid the factor. However, a portion of the reef may be lost so intolerance is reported to be intermediate. In addition, it is also likely that too much sediment on the surface of rocks or tubes would prevent settlement of larvae (Holt et al., 1998) and so may also reduce the long term growth of the reef. As individuals of Serpula vermicularis remain alive and the hard substratum of the reef is available for settlement of new individuals recovery is reported to be high, hence sensitivity is low - additional information below for full rationale.
Low Immediate Not sensitive No change Low
Siltation can have a negative impact on site selection by larvae (Rodriguez et al., 1993). Bosence (1979b) concluded from observations and from transplant experiments, that the lower depth limit of Serpula vermicularis was probably determined by suspended sediment and de-oxygenation. In contrast Moore et al. (1998b) found no horizontal layers of suspended mud in Loch Creran, and although the authors do not rule out the possibility that storm-generated, suspended mud may inhibit reef development, the lower limit of reefs could also be due to inadequate current velocities for suspension feeding. Chapman et al., (2007) suggested that the lower depth limit was a result of depth-correlated settlement response of larvae.
A supply of suspended sediment may be important to Serpula vermicularis because the species requires a supply of particulate matter for suspension feeding. However, at the benchmark level of an increase of 100mg/l for one month, the likely impact would be an increase in cleaning costs. Thus, the biotope is not likely to be significantly affected and a rank of low is reported. Other suspension feeding species in the biotope may be more intolerant of suspended sediment levels, although at the level of the benchmark, effects are likely to be largely sub-lethal. Recovery will be immediate as normal feeding returns on the resumption of pre-impact conditions. Other species that may be lost are likely to recolonise rapidly. Hence a suggested sensitivity ranking of not sensitive.
Low High Not relevant Minor decline Moderate
A supply of suspended sediment for feeding is probably important to Serpula vermicularis and other suspension feeders in the biotope. However, the species is an active suspension feeder creating its own feeding currents so is not likely to be highly intolerant of changes in suspended sediment. Bosence (1979b) also suggests that increases in suspended sediment limit the distribution of Serpula vermicularis, so a decrease is not expected to be detrimental. Other species in the biotope are not likely to be significantly affected by a decrease for a month. Therefore, a rank of low is reported and recovery will be very rapid, resulting in a rank of not sensitive.
Not relevant Not relevant Not relevant Not relevant Not relevant
The biotope is found in the circalittoral and so desiccation is not a relevant factor.
Not relevant Not relevant Not relevant Not relevant Not relevant
The biotope is found in the circalittoral and so emergence is not a relevant factor.
Not sensitive*
The biotope is found in the circalittoral and so emergence is not a relevant factor.
High Very low / none Very High Major decline High
Reefs appear to occur mainly in areas sheltered from strong water flow. For example, in Loch Creran no reefs were recorded in the outer section of the loch beyond the narrows at Sgeir Calliach, despite the presence of suitable depths and substrates. This is a well-flushed section of the loch, where the larvae of Serpula vermicularis will presumably be at lower concentrations than further up the loch (Moore, 1998b). Therefore, the biotope will be intolerant of an increase in water flow rate as larvae are likely to be taken away from the reefs, old worms will die and without a supply of new individuals the reef will die. With the collapse of dead Serpula reefs, species diversity will decline significantly because the open structure of the reefs provides substratum and crevices for many other organisms. Intolerance of the biotope is therefore, set to high. Recovery from complete loss of reefs is unlikely or at best very slow, so suggested recoverability is very low, resulting in a high sensitivity rating - see additional information.
Not sensitive* High
Serpula vermicularis reefs only develop in sheltered areas where there is little water movement and larvae are thought to be prevented from being carried away. Therefore, since populations can survive in low water flow environments intolerance is reported to be low. However, a reduction in water flow may reduce food supply although this will probably not have a huge impact on the suspension feeding Serpula vermicularis because the species can generate its own feeding currents. Reduced water flow may allow the deposition of silt which is thought to create unfavourable conditions for the settlement of larvae (Cotter et al. 2003). On return to normal conditions, recovery would be quick so is deemed very high, hence a very low sensitivity rating.
Low High Low No change Low
Serpula vermicularis has a broad geographical range which suggests that it is tolerant of some temperature change. In Loch Creran in Scotland, the temperature regime within the main basin is similar to that in the adjacent sea with a low of about 6°C in February/March and a high of 13 - 15°C in August/September (Gage, 1972). The peak in larval recruitment of Serpula vermicularis in loch Creran coincides with this peak in temperature (Chapman et al., 2007). Additionally, Hughes et al., (2005) found the species to be tolerant of changes in temperature “with upper lethal limits exceeding any value that they could conceivably experience in the field”. Therefore a rank of low intolerance is reported. Some other species in the biotope may be more intolerant of increases in temperature although overall species diversity is not expected to be significantly affected. Recoverability is likely to be high provided larval supply is adequate, so recoverability is rated as low, giving a low sensitivity rank.
Low High Low No change Low
Serpula vermicularis has a broad geographical range which suggests that it is unlikely to be very intolerant of temperature changes. It would be expected that in shallow enclosed areas, temperature will fall during periods of cold winter weather so decreases in temperature are probably tolerated by reefs. Hughes et al., (2005) found the species to be tolerant of a wide range of temperatures, therefore a rank of low intolerance is reported. Some other species in the biotope may be more intolerant of decreases in temperature although overall species diversity is not expected to be significantly affected. Recoverability is likely to be high provided larval supply is adequate, so recoverability is rated as low, giving a low sensitivity rank.
Low Very high Very Low No change Moderate
An increase in turbidity, reducing light availability, may reduce primary production by phytoplankton in the water column. Tett and Edwards (2002) noted that the level of phytoplankton abundance in Loch Creran is high for Scottish coastal waters, and it has been suggested that high food availability (Ten Hove, 1979) and increased primary productivity (Bosence, 1979) may contribute to reef formation. However, productivity in the CMS.Ser biotope is predominantly secondary (detritus based) and although an increase in turbidity may reduce the phytoplankton contribution to detritus, any effects at the level of the benchmark, are not likely to be significant. There are some red algae present in the biotope and so an increase in turbidity may reduce photosynthesis and growth because of light attenuation. However, this is not likely to affect the nature of the biotope and so intolerance of the biotope is assessed as low. On return to normal conditions recovery would be swift, hence a rating of very fast, and therefore a sensitivity of very low.
Low Very high Moderate No change Moderate
A decrease in turbidity will increase light availability which could improve levels of primary production. Phytoplankton in the water column may become more abundant at certain times of the year improving overall food supplies for suspension feeders. It has been suggested that increased food supply (Ten Hove, 1979) and increased primary productivity (Bosence, 1979) may contribute to reef formation. An improvement in light availability may also lead to an increase in the growth of algae which may be able to out-compete Serpula vermicularis in the colonization of hard surfaces. However, a decrease in turbidity for a month is not likely to have a significant impact on the biotope so intolerance is reported to be low. On return to normal conditions recovery would be swift, hence a rating of very fast, and therefore a sensitivity of very low.
Not relevant Not relevant Very High Major decline High
In the sheltered areas such as sea lochs, where Serpula vermicularis aggregates to create reefs, the species grows upwards and outwards. The reefs are fairly open and quite fragile and so are likely to be intolerant of wave exposure, and no reefs are reported at depths of 0 m, which may be the effect of turbulence on larval recriutment (Champan et al., 2007). Loss of the reefs will also result in a major loss of species diversity. However in sea lochs a change in wave exposure is unlikely to occur other than over geological timescales, therefore sensitivity is assessed as not relevant. See additional information for recovery information.
Not sensitive* High
The biotope occurs in very sheltered sea lochs where wave exposure is minimal and so is not likely to be sensitive to a decrease. In sea lochs a change in wave exposure is unlikely to occur other than over geological timescales, therefore sensitivity is assessed as not relevant.
Tolerant Not relevant Not relevant Not relevant High
At the level of the benchmark Serpula vermicularis, or any of the associated species, are not likely to be sensitive to noise but may respond to the vibrations associated with noise as a predator avoidance mechanism. However, at the level of the benchmark reefs will not be sensitive to noise.
Tolerant Not relevant Not relevant Not relevant High
Serpula vermicularis has been observed to react to the visual presence of moving objects not naturally found in the marine environment (e.g., boats, machinery, and humans). It is sensitive to a sudden decrease in light levels as a predator avoidance mechanism (Poloczanska et al., 2004). Also, in areas popular with SCUBA divers, it is possible that flash photography may result in a reduction in feeding, as grey literature reports that light stimuli cause the retraction of feeding apparatus. However, at the level of the benchmark this is not thought to affect the biotope and tolerant is the suggested sensitivity level.
High High Moderate Major decline High
Serpula vermicularis are fragile and can be easily damaged. For example, in Loch Creran severe damage, although only on a local scale, was caused by movement of mooring blocks and chains (Moore, 1996). Although the effects were localized, mooring had reduced colonies to rubble within a radius of 10 m in one instance, and extensive damage was reported within 50 m of salmon cages (Holt et al., 1998). Holt et al. (1998) suggested that fishing activity could be very damaging but that no evidence of damage had yet been observed. Although individual worms survived and were seen to continue feeding, the reefs were broken up so that the value of the habitat was greatly diminished. A passing scallop dredge is likely to result in more damage. In Loch Creran individual reefs are reported to reach a height of about 75cm and 1m across, although adjacent reefs may coalesce to form larger reefs up to 3m across (Moore, 1996). In either case, a passing beam trawl or scallop dredge could destroy the entire reef. Intolerance of the biotope is therefore, reported to be high. Pieces of reef broken off from the main reef may continue to grow as new worms attach to fragments (Bosence, 1979b). Therefore, as individuals will remain, the re-establishment of reefs is possible and so recovery is reported to be high, and sensitivity moderate - see additional information below.
High Very low / none Very High Major decline High
Serpula vermicularis lives in a calcareous tube that is permanently attached to the substratum. It is unlikely that the worm is able to rapidly build a new tube if displaced and so would probably die. Many of the other species in the biotope are also sessile, usually attached to the reef, so will also be unable to reattach if displaced. Intolerance is therefore, reported to be high. See additional information for recovery, which is rated very low, giving a very high sensitivity rating.

Chemical Pressures

 IntoleranceRecoverabilitySensitivityRichnessEvidence/Confidence
No information No information No information Insufficient
information
Not relevant
Insufficient
information.
Heavy metal contamination
Low No information No information Insufficient
information
Not relevant
Serpula vermicularis was found at Garric Roads, close to Restronguet Creek in the Fal estuary, that is contaminated with high levels of metals, in particular copper, zinc and arsenic (Bryan & Gibbs, 1983). It was also found in the laboratory that levels of mercury far higher than those naturally encountered by Serpula vermicularis are required to have a toxic effect on the species (Gray, 1976). Therefore, it appears that the species can tolerate some enhanced heavy metal concentrations and so intolerance is reported to be low.
Hydrocarbon contamination
No information No information No information Insufficient
information
Not relevant
Insufficient
information.
Radionuclide contamination
No information No information No information Insufficient
information
Not relevant
Insufficient
information.
Changes in nutrient levels
No information No information No information Minor decline Very low
In Loch Creran in Scotland, where Serpula vermicularis forms extensive reefs, organic effluent from an alginate factory appeared to have been responsible for eliminating reefs for a distance of about 1km and may have reduced reef development at greater distances (Moore et al., 1998b). However, this level of organic pollution was extreme, with much of the seabed becoming covered in a thick bacterial mat, and does not give any indication of the intolerance of Serpula vermicularis reefs to a benchmark increase in nutrients of 50%. Species diversity may decline but the overall impact on reefs is unknown.
High Very low / none Very High Major decline Very low
Serpula vermicularis is not found in areas where hypersaline conditions may occur, such as rock pools or lagoons, so it seems likely that the species would be intolerant of increases in salinity. A long term increase to hypersaline conditions would probably result in loss of reefs, and the loss of many of the other the other species that colonize the reefs, so intolerance is set to high but with a very low confidence. Recovery from loss of reefs is likely to be very slow if at all, hence a very high sensitivity - see additional information below.
Intermediate High Low Minor decline Moderate
Bosence (1979b) suggests that the layer of lower salinity water in the upper layers of the water in Ardbear Loch in Galway, Eire is partly responsible for the lack of individuals above a depth of 2m. However, Serpula vermicularis are known to tolerate reduced salinities (Hartmann-Schröder, 1971 and Mastrangelo & Passeri, 1975, cited in Moore et al., 1998b) and in Loch Creran in Scotland individual specimens of Serpula vermicularis were commonly observed in shallow waters were salinities can fall to around 23psu. Small enclosed lochs such as Loch Sween & Ardbear Loch are often subject to extremely variable salinity so the species seems to be tolerant of shorter term changes. Serpula vermicularis reefs were also observed in intertidal areas of Loch Creran, where salinity is likely to vary, during the 19th century. Therefore, it seems likely that the species can tolerate some decreases in salinity. However, when reduced salinity interacts with variation in temperature, larval mortality occurs (Gray, 1976). Also, long term reductions would probably reduce abundance so intolerance is set to intermediate. Some of the other species found in association with the Serpula vermicularis reefs may be intolerant of decreases in salinity leading to a possible reduction in the overall species diversity of the reef. When individuals of Serpula vermicularis remain after a perturbation, recovery should be possible and is set to high, thus sensitivity is low - see additional information below for full rationale.
Intermediate High Low Minor decline Moderate
There is no information regarding the tolerance of Serpula vermicularis to deoxygenation. Cole et al. (1999) suggest possible adverse effects on marine species below 4 mg/l and probable adverse effects below 2mg/l. Bosence (1979b) observed that the lower limit of larval settlement in Ardbear Lough, Eire coincided with mud-rich and possibly oxygen poor water. Therefore, the species, and the larvae in particular, may be intolerant of deoxygenated water and a rank of intermediate is reported. Gage (1972) found the dissolved oxygen concentration in the lower basin of Loch Creran in Scotland, where Serpula vermicularis reefs form, did not fall below 87% saturation. Other species in the biotope may also be intolerant of changes in oxygen availability resulting in a possible loss of species diversity. On return to normal conditions recovery would be swift, hence a rating of very fast, and therefore a sensitivity of low.

Biological Pressures

 IntoleranceRecoverabilitySensitivityRichnessEvidence/Confidence
Low High Low No change Low
No information on diseases of Serpula vermicularis was found. However, the species is known to be parasitized by the protozoan Haplosporidium parisi (Ormieres, 1980) but the effects of this infestation are unknown. There are no reports of loss of the biotope from disease. However there is always the potential for this to occur.
No information No information Low No change No information
Although several species of serpulid polychaetes have been introduced into British waters none are reported to compete with Serpula vermicularis (Eno et al., 1997). However, there is always the potential for introduced species to either compete with, or prey upon Serpula vermicularis.
High High Moderate No change Moderate
Small scale collection of Serpula vermicularis by divers for commercial aquaria takes place in Loch Creran (Moore, 1996) although it appears that this limited collection is sustainable. However, the reef areas often contain reasonable stocks of the queen scallop, Aequipecten opercularis, and there are occasional reports of shallow-water dredging in Loch Creran in Scotland (Moore et al., 1998b). Serpula vermicularis are fragile and can be easily damaged. Holt et al. (1998) suggested that fishing activity could be very damaging but that no evidence of damage had yet been observed. Although individual worms survived and were seen to continue feeding, the reefs were broken up so that the value of the habitat was greatly diminished. A passing scallop dredge is likely to result in more damage. In Loch Creran individual reefs are reported to reach a height of about 75cm and 1m across, although adjacent reefs may coalesce to form larger reefs up to 3m across (Moore, 1996). In either case, a passing beam trawl or scallop dredge could destroy the entire reef. Intolerance of the biotope is therefore, reported to be high. Pieces of reef broken off from the main reef may continue to grow as new worms attach to fragments (Bosence, 1979b). Therefore, as individuals will remain, the re-establishment of reefs is possible and so recovery is reported to be high, thus sensitivity is low - see additional information below.
Low High Low No change Moderate

Additional information

Recoverability
Serpula vermicularis probably reaches sexual maturity in its first year and reproduces every year thereafter. The planktonic larvae, which is thought to stay in the water column for one to eight weeks, may be able to disperse widely and so generally recovery rates of the species would be high. However, in the sheltered and enclosed areas where Serpula vermicularis forms reefs recovery may not be possible if populations are completely lost. This is because the factor that enables the reefs to develop, i.e. limited water exchange keeping larvae in the local system, also limits the supply of larvae from coastal waters to replace populations if they disappear. Therefore, if local populations of Serpula vermicularis are completely lost recovery of the key species, and therefore the biotope, will be extremely slow, if at all. So, where a factor is likely to result in complete loss of populations a recovery rank of very low has been reported. However, if individuals of Serpula vermicularis remain after a perturbation recovery of the reefs should be possible because recruitment from local populations can occur. For example, Moore (unpublished in Holt et al., 1998) found that dense aggregations of Serpula vermicularis up to about 15cm in height were present on bare substratum after 3 months, so re-establishment of reefs should be possible within five years. Therefore, if the factor is not likely to result in a complete loss of populations a recovery rank of high is reported. The other species in the biotope, such as ascidians, sponges, hydroids and other polychaetes, are likely to be iteroparous with planktonic larvae so that recovery should be possible within a few years. However, many of these species have short-lived larvae so if local populations are completely lost recovery may take longer because of the limited water exchange found in the locations where this biotope develops. Recovery of the biotope is determined primarily by the recovery of Serpula vermicularis.

Importance review

Policy/Legislation

Habitats of Principal ImportanceSerpulid reefs [Scotland]
Habitats Directive Annex 1Large shallow inlets and bays, Reefs
UK Biodiversity Action Plan PrioritySerpulid reefs
Priority Marine Features (Scotland)Serpulid aggregations

Exploitation

  • Small scale collection of Serpula vermicularis by divers for commercial aquaria takes place in Loch Creran (Moore, 1996). It appears that this limited collection is sustainable but there are no estimates of the maximum sustainable rate of removal making predictions of the effects of increased collection difficult (Holt et al., 1998).
  • Although the Pecten maximus population is probably too low to attract scallop dredgers, reef areas often contain reasonable stocks of the queen scallop, Aequipecten opercularis, and there are occasional reports of shallow-water dredging in Loch Creran in Scotland (Moore et al., 1998b).

Additional information

Although 'reefs' are an Annex 1 feature, the EC Habitats Directive make no mention of 'biogenic reefs' (Holt et al., 1997). However, the possible citing of biogenic reefs as a specific reason for selecting SACs is under review and may be proposed in the future (Brown et al., 1997).

Bibliography

  1. Bosence, D.W.J., 1979b. The factors leading to aggregation and reef formation in Serpula vermicularis L. In Proceedings of an International Symposium held at the University of Durham, April 1976. Biology and Systematics of Colonial Organisms (ed. G. Larwood & B.R. Rosen), pp. 299-318. London: Academic Press.
  2. Brown, A.E., Burn, A.J., Hopkins, J.J. & Way, S.F., 1997. The habitats directive: selection of Special Areas of Conservation in the UK. Joint Nature Conservation Committee, Peterborough, JNCC Report no. 270.
  3. Bryan, G.W. & Gibbs, P.E., 1983. Heavy metals from the Fal estuary, Cornwall: a study of long-term contamination by mining waste and its effects on estuarine organisms. Plymouth: Marine Biological Association of the United Kingdom. [Occasional Publication, no. 2.]
  4. Cole, S., Codling, I.D., Parr, W. & Zabel, T., 1999. Guidelines for managing water quality impacts within UK European Marine sites. Natura 2000 report prepared for the UK Marine SACs Project. 441 pp., Swindon: Water Research Council on behalf of EN, SNH, CCW, JNCC, SAMS and EHS. [UK Marine SACs Project.], http://www.ukmarinesac.org.uk/
  5. Cotter, E., O'Riordan, R.M & Myers, A.A. 2003. Recruitment patterns of serpulids (Annelida: Polychaeta) in Bantry Bay, Ireland. Journal of the Marine Biological Association of the United Kingdom, 83, 41-48.
  6. Davies, C.E. & Moss, D., 1998. European Union Nature Information System (EUNIS) Habitat Classification. Report to European Topic Centre on Nature Conservation from the Institute of Terrestrial Ecology, Monks Wood, Cambridgeshire. [Final draft with further revisions to marine habitats.], Brussels: European Environment Agency.
  7. Eno, N.C., Clark, R.A. & Sanderson, W.G. (ed.) 1997. Non-native marine species in British waters: a review and directory. Peterborough: Joint Nature Conservation Committee.
  8. Gage, J., 1972. A preliminary survey of the benthic macrofauna and sediments in Lochs Etive and Creran, sea-lochs along the west coast of Scotland. Journal of the Marine Biological Association of the United Kingdom, 52, 237-276.
  9. Holt, T.J., Rees, E.I., Hawkins, S.J. & Seed, R., 1998. Biogenic reefs (Volume IX). An overview of dynamic and sensitivity characteristics for conservation management of marine SACs. Scottish Association for Marine Science (UK Marine SACs Project), 174 pp.
  10. MBA (Marine Biological Association), 1957. Plymouth Marine Fauna. Plymouth: Marine Biological Association of the United Kingdom.
  11. Michel, C. & De Villez, E.J., 1978. Digestion. In Physiology of Annelids (ed. P.J. Mill), pp. 509-554. London: Academic Press.
  12. Minchin, D., 1987. Serpula vermicularis L. (Polychaeta: Serpulidae) reef communities from the west coast of Ireland. Irish Naturalists' Journal, 22, 314-316.
  13. Moore, C.G., 1996. Distribution of the serpulid reefs in Loch Creran, Argyll. Unpublished, Scottish Natural Heritage, Survey and Monitoring Report no. 53.
  14. Moore, C.G., Saunders, G.R. & Harries, D.B., 1998b. The status and ecology of reefs of Serpula vermicularis L.. Aquatic Conservation: Marine and Freshwater Ecosystems, 8, 645-656.
  15. Norton, T.A., 1992. Dispersal by macroalgae. British Phycological Journal, 27, 293-301.
  16. Ormieres, R., 1980. Haplosporidium parisi sp. nov., a parasite of Serpula vermicularis. Ultrastructural study of the spore. Protistologica, 16, 467-474.
  17. Poloczanska, E.S., Hughes, D.J. & Burrows, M.T., 2004. Underwater television observations of Serpula vermicularis (L.) reefs and associated mobile fauna in Loch Creran, Scotland. Estuarine, Coastal and Shelf Science, 61, 425-435.

Citation

This review can be cited as:

Hill, J.M. & Wilding C.M. 2008. Serpulid aggregations. In Tyler-Walters H. and Hiscock K. (eds) Marine Life Information Network: Biology and Sensitivity Key Information Reviews, [on-line]. Plymouth: Marine Biological Association of the United Kingdom. Available from: http://www.marlin.ac.uk/habitat/detail/41

Last Updated: 06/11/2008