Biodiversity & Conservation

SS.IMX.EstMx.MytV

Explanation of sensitivity and recoverability


Physical Factors

Substratum Loss
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Removal of the substratum will remove of all the species within the biotope. Therefore, an intolerance of high has been recorded. Although a single good recruitment event may recolonize the substratum within a year, recovery may take up to 5 years, and is some circumstances significantly longer (see additional information below). Therefore, a recoverability of high has been recorded.
Smothering
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Intertidal Mytilus edulis beds have been reported to suffer moralities as a result on smothering by large scale movements of sand or sand scour (Holt et al., 1998; Daly & Mathieson, 1977). Similarly, biodeposition within a mussel bed results in suffocation or starvation of individuals that cannot re-surface. Young mussels have been shown to move up through a bed, avoiding smothering, while many others were suffocated (Dare, 1976; Holt et al., 1998). This suggests that a proportion of the population may be able to avoid smothering in subtidal conditions, and, therefore, an intolerance of intermediate has been recorded. Many infaunal species are likely to be not sensitive to smothering by the same grade of sediment, however, interstitial species and epifauna may be adversely affected. Although a single good recruitment event may recolonize the substratum within a year, recovery may take up to 5 years, and is some circumstances significantly longer (see additional information below). Therefore, a recoverability of high has been recorded.
Increase in suspended sediment
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Mytilus edulis has been reported to be relatively tolerant of suspended sediment and siltation and survived over 25 days at 440mg/l and on average 13 days at 1200mg/l (Purchon, 1937; Moore, 1977a). Mytilus edulis also has efficient pseudofaeces discharge mechanisms (Moore, 1977a; de Vooys, 1987). Asterias rubens flourishes in naturally turbid conditions and is capable of cleansing itself of adherent mud particles (Moore, 1977). Nucella lapillus is also found in turbid environments such as the Bristol Channel. Similarly, the barnacle Balanus crenatus was considered to be of low intolerance to suspended sediment. However, these species probably suffer a metabolic cost resulting from the cleansing mechanisms, mucus production and interrupted or impaired feeding. Therefore, a biotope intolerance of low, at the benchmark level, has been recorded. The majority of the organisms within the biotope are adapted to sedimentary, estuarine habitats and probably have mechanisms to deal with siltation and suspended sediment, so that recoverability of immediate has been recorded.
Decrease in suspended sediment
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A decrease in suspended sediment, especially organic particulate could potentially reduce the food available to Mytilus edulis and the other suspension feeders within the biotope. A reduction in sedimentation could potential result in increased rates of erosion in sedimentary habitats. However, a large proportion of deposition within the mussel bed is due to accumulation of faeces and pseudofaeces. Therefore, a decrease in sedimentation at the benchmark level is probably not significant and an intolerance of low has been recorded.
Desiccation
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This biotope occurs from 0 -10m in depth and, therefore, only populations in the shallowest parts of its distribution may be exposed to desiccation by extreme low tides. The upper limit of Mytilus edulis population is primarily controlled by the synergistic effects of temperature and desiccation (Suchanek, 1978; Seed & Suchanek, 1992; Holt et al., 1998). However, Mytilus spp. beds occur in the mid to lower intertidal, so that a change in desiccation at the benchmark level is unlikely to adversely affect the bed. Similarly, Nucella lapillus also occur in the intertidal and is unlikely to be adversely affect at the benchmark level.
Asterias rubens has a high surface to volume ratio and is highly intolerant of desiccation. Its distribution is restricted to the sublittoral, or sublittoral fringe. Most infauna or interstitial fauna are protected from desiccation by their habitat but can tolerate intertidal conditions. Therefore an intolerance of low has been recorded at the benchmark level.
Increase in emergence regime
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An increase in emergence will effectively move the upper limits of the biotope into the lower intertidal. Mytilus edulis can form extensive beds in the intertidal. Growth rates will decrease due to loss of feeding time at low tide. However, the major predators will probably change, from the starfish and crabs of the sublittoral to birds and wildfowl in the eulittoral. Dog whelk predation will probably remain about constant, while fish predation will be limited to high tides. Most of the epifauna and infaunal polychaetes and amphipods are recorded from the lower shore and likely to be little affected. However, wildfowl predation may be significant, and is likely to change to size and age distribution within the bed and disrupt the mussel bed itself, e.g. eider duck, therefore an intolerance of intermediate has been recorded. Recovery is likely to be rapid (see additional information).
Decrease in emergence regime
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An increase in tidal submergence is likely to allow the biotope to extend its range further up the shore. Therefore, a rank of not sensitive* has been recorded.
Increase in water flow rate
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As mussel beds increase in size and depth, individual mussels become increasingly attached to each other rather than the substratum. As a result, the bed may become destabilised and susceptible to removal by wave action or tidal scour. However, mussels at the edge of the beds are often more strongly attached than mussels within the bed (Seed & Suchanek, 1992). On sedimentary shores, mussel beds are probably intolerant of increased water flow due to removal of the sediment resulting in loss of clumps of the bed. Mussel reefs in the Wash, Morecambe Bay and the Wadden Sea are vulnerable to destruction by storms and tidal surges (Holt et al., 1998). Therefore, a change in water flow rate from weak to strong (the benchmark) would probably result in the loss of clumps or large parts of the mussel bed, Loss of the bed would result in loss of the epifaunal and predatory species associated with them, together with the interstitial fauna and a proportion of the benthic infauna. Therefore, an intolerance of high has been recorded.
Although a single good recruitment event may recolonize the substratum within a year, recovery may take up to 5 years, and is some circumstances significantly longer (see additional information below). Therefore, a recoverability of high has been recorded.
Decrease in water flow rate
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This biotope is found in moderately strong to weak tidal streams and further reduction in water flow may result in an increased sedimentation (see above) and risk of low oxygen conditions (see below). The mussels, and other suspension feeders, probably require water flow to supply food (suspended particulates, benthic diatoms and phytoplankton). However, overall a reduction in water flow is likely to have only limited affects and an intolerance of low and a recoverability of very high has been recorded.
Increase in temperature
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Sublittoral populations are unlikely to experience rapid or extreme temperature changes due to natural events and may, therefore, be expected to be intolerant of acute temperature change. An upper, sustained temperature tolerance limit of about 29 °C has been reported for Mytilus edulis in the United Kingdom (Read & Cumming, 1967; Almada-Villa et al., 1982). Seed & Suchanek (1992) noted that European populations were unlikely to experience temperatures greater than 25°C. Therefore, Mytilus edulis was consider to be of low intolerance to temperature change. Nucella lapillus may succumb to increased temperatures in summer but is otherwise relatively tolerant. Balanus crenatus and Asterias rubens, however, were assessed as highly intolerant of increased temperatures. Overall, the biotope has been assessed as of low intolerance to increased temperatures since the key species, Mytilus edulis, is unlikely to be adversely affected. Recovery is likely to be rapid (see additional information below).
Decrease in temperature
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Sublittoral populations are unlikely to experience rapid or extreme temperature changes due to natural events and may, therefore, be expected to be intolerant of acute temperature change. However, Mytilus edulis tolerates decreases in temperature and even freezing for short periods. Mytilus edulis was relatively little affected by the severe winter of 1962/63, with 30% mortality reported from south-east coasts of England (Whitstable area) and ca. 2% from Rhosilli in south Wales (Crisp (ed.),1964). Similarly, the barnacle Balanus crenatus, were unaffected by the severe winter of 1962/63 (Crisp, 1964). Most of the polychaetes characterizing the biotope have a wide distribution and are probably tolerant of low temperatures, especially when protected from temperature change by their infaunal habit. It appears, therefore, that most of the characterizing species within the biotope are tolerant of an acute short term temperature decrease and a biotope intolerance of low has been recorded. Recovery is likely to be rapid (see additional information below).
Increase in turbidity
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This biotope is an animal dominated community, dependant on secondary production and not dependant on light. Therefore, the biotope is probably not sensitive to changes in turbidity and light attenuation.
Decrease in turbidity
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This biotope is an animal dominated community, dependant on secondary production and not dependant on light. Therefore, the biotope is probably not sensitive to changes in turbidity and light attenuation.
Increase in wave exposure
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The intolerance of mussel beds probably owes more to the nature of the substratum than the strength of their attachment. Individuals attached to solid substrata (rock) are likely to be more tolerant than individuals attached to boulders, cobbles or sediment. Harger & Landenberger (1971) noted that, on gravel based substratum, small, single layered mussel beds suffered far less damage from storms that heavy, multi-layered beds. As mussel beds grow in size and thickness relatively fewer mussels are directly attached to the substratum, so that heavy seas can "roll up the whole mass of mud and mussels like a carpet and break it to pieces on the foreshore" (Harger & Landenberger, 1971). Storms and tidal surges are known to destroy mussel beds, often over hundreds of hectares in the Wash, Morecambe Bay and the Wadden Sea. Mussels beds persist in sheltered areas whereas beds in exposed areas are more dynamic (Holt et al., 1998). Although, subtidal beds are protected by depth, in the shallow sublittoral occupied by this biotope wave action may still be significant. An increase in wave action from sheltered to exposed (the benchmark) is likely to remove a large proportion of the bed, the remaining mussel mud and modify the average grain size of the sediment (from fine to coarse) resulting in major changes in the benthic infauna. Therefore an intolerance of high has been recorded. Recovery may take up to 5 years or longer once prior conditions return (see additional information below) and a recoverability of high has been recorded.
Decrease in wave exposure
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On wave sheltered sedimentary shores decreased wave exposure (i.e. sheltered to very sheltered) is likely to have little affect on mussel beds. Therefore, sheltered shore mussels beds are probably of low intolerance to decreased wave exposure, and may be less patchy and more stable (persistent). Reduced wave action will decrease water flow over the bed (see above) and may increase the risk of deoxygenation (see below).
Noise
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Mytilus edulis and most invertebrate species within the biotope are probably insensitive to noise disturbance at the levels of the benchmark.
Visual Presence
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Mytilus edulis and most invertebrate species within the biotope are probably insensitive to visual disturbance at the levels of the benchmark.
Abrasion & physical disturbance
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Wave driven logs have been reported to influence Mytilus edulis populations, causing the removal of patches from extensive beds that subsequently open the beds to further damage by wave action (Holt et al., 1998). A similar effect could be caused by a vessel grounding. Little information on physical disturbance in subtidal Mytilus spp. beds was found. Fishing activities, e.g. scallop dredging are know to physically disturb marine communities. Modiolus modiolus beds have been reported to have declined off the Isle of Man due to scallop dredging, presumably because the scallop dredging activity had damaged the edges of denser beds over time (Jones, 1951; Holt et al., 1998). Benthic trawls, where they occur, may affect Mytilus edulis beds similarly.

Of the other species in the biotope, starfish, such as Asterias rubens, have been reported to be damaged by benthic dredges but have considerable regenerative capability, and, as scavengers, benefit from the presence of other damaged or killed animals (Emson & Wilkie, 1980; Gubbay & Knapman, 1999). Therefore, it is likely that abrasion or impact at the level of the benchmark (a scallop dredge) would damage or remove patches of the population and an intolerance of intermediate has been recorded. Recovery is dependant on recruitment of Mytilus edulis and a recoverability of high has been reported (see additional information below).

Displacement
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Mytilus edulis is capable of re-attaching itself to suitable substrata once displaced. Dislodgement may result in increased risk of predation and some individuals may be lost if swept to unsuitable substrata. Overall, however, displacement will result in loss of mussels from this biotope. Displaced starfish are unlikely to be adversely affected and could probably return. Permanently attached species within the community such as barnacles, bryozoans and tubeworms are likely to be lost as a result of displacement. Overall, a proportion of the mussel bed would probably survive displacement and an intolerance of intermediate has been recorded. However, other members of the community are probably more intolerant, resulting in a decline in species richness until they are able to recolonize. Recovery is dependant on recruitment of Mytilus edulis and a recoverability of high has been reported (see additional information below).

Chemical Factors

Synthetic compound contamination
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The effects of contaminants on Mytilus edulis were extensively reviewed by Widdows & Donkin (1992) and Livingstone & Pipe (1992). Overall, Mytilus edulis is probably relatively tolerant of contaminants, although mortalities have been recorded (see species review for details). For example,
  • Widdows et al., (1995) noted that polar organics, and organo-chlorines reduced scope for growth in Mytilus edulis;
  • Mytilus edulis has been shown to accumulate PCBs and ivermecten (Hummel et al., 1989; Cole et al., 1999; Holt et al., 1995);
  • the presence of poly-aromatic hydrocarbons, cis-chlordane pesticides and cadmium has been associated with an increase in tumours in Mytilus edulis (Hillman, 1993; Holt et al., 1998); and
  • mussels may be absent from areas of high boating activity, presumably due to TBT (Holt et al., 1998).
Muricid gastropods such as Buccinum undatum but especially Nucella lapillus are highly intolerant of TBT pollution resulting in significant declines in the population of the dog whelk. Barnacles, such as Balanus crenatus were considered to be highly intolerant of chemical contaminants (Holt et al., 1995). Similarly, most pesticides and herbicides were suggested to be very toxic for invertebrates, especially crustaceans (amphipods, isopods, mysids, shrimp and crabs) and fish (Cole et al., 1999). For example, Lindane was shown to be very toxic to gobies Gobius spp. (see the Pomatoschistus minutus review) (Ebere & Akintonwa, 1992) . The pesticide ivermectin is very toxic to crustaceans, and has been found to be toxic towards some benthic infauna such as Arenicola marina (Cole et al., 1999).
Therefore, chemical contamination may cause mortalities and sub-lethal effects in the Mytilus edulis bed but affect other members of the community to varying degrees, and an overall intolerance of intermediate has been recorded.
Most members of the community will recolonize rapidly and a recoverability of high has been reported (see additional information below).
Heavy metal contamination
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Lethal threshold concentrations for several heavy metals have been determined in Mytilus edulis (see species review; Widdows & Donkin (1992) and Livingstone & Pipe (1992) for reviews). Mussels were also reported to be missing from a wider area of the Cumbrian coast than other organisms in the vicinity of a phosphate rich effluent contaminated by heavy metals (Holt et al., 1998). Widdows & Donkin (1992) noted that lethal responses give a false impression of high tolerance. However, Mytilus edulis is probably relatively tolerant of heavy metal contamination. Besten et al. (1989) suggested that cadmium (Cd) pollution posed a significant threat to populations of Asterias rubens since it affected reproduction.
Cole et al. (1999) suggested that Pb, Zn, Ni and As were very toxic to algae, while Cd was very toxic to Crustacea (amphipods, isopods, shrimp, mysids and crabs), and Hg, Cd, Pb, Cr, Zn, Cu, Ni, and As were very toxic to fish. Gobies were reported to be particularly intolerant of Hg (see Pomatoschistus minutus). Bryan (1984) reported sublethal effects of heavy metals in crustaceans at low (ppb) levels. Bryan (1984) suggested that polychaetes are fairly resistant to heavy metals, based on the species studied. Short term toxicity in polychaetes was highest to Hg, Cu and Ag, declined with Al, Cr, Zn and Pb whereas Cd, Ni, Co and Se were the least toxic. However, he suggested that gastropods (e.g. limpets, Nucella lapillus and Buccinum undatum) were relatively tolerant of heavy metal pollution. Therefore, given the evidence of sub-lethal and lethal effects of heavy metals in Mytilus edulis a biotope intolerance of intermediate has been reported.
Hydrocarbon contamination
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The effects of contaminants on Mytilus edulis were extensively reviewed by Widdows & Donkin (1992) and Livingstone & Pipe (1992). Overall, Mytilus edulis is probably relatively tolerant of contaminants, although mortalities have been recorded (see species review for details). Sublittoral populations are protected from the immediate effects of oil spills by their depth. Therefore, hydrocarbon contamination in sublittoral populations is limited to exposure to lighter oil fractions and PAHs in solution, as droplets as a result of wave exposure or adsorbed onto particulates.
  • Toxic hydrocarbons and PAHs contribute to a decline on the scope for growth in Mytilus edulis (Widows & Donkin, 1992; Widdows et al., 1995).
  • The presence of poly-aromatic hydrocarbons, cis-chlordane pesticides and cadmium gas been associated with an increase in tumours in Mytilus edulis (Hillman, 1993; Holt et al., 1998).
  • Mesocosm experiments have shown high mortalities of Mytilus edulis exposed to the water accommodated fraction of diesel (Widdows et al., 1987; Bokn et al., 1993).
  • Ingestion of droplets of sunflower oil, from a tanker spill off the Anglesey coast resulted in mortalities after spawning (Mudge et al., 1993; Holt et al., 1998).
  • Asterias rubens suffered mass mortalities after the Torrey Canyon oil spill and was reported to be lost from mesocosms treated with the water accommodated fraction of diesel (Smith, 1968; Bokn et al., 1993).
  • Mytilus edulis dominated jetty piles immediately adjacent to an oil refinery effluent in Milford Haven, suggesting a high tolerance of hydrocarbon contamination (K. Hiscock, pers. comm.).
Overall, Mytilus edulis is probably relatively tolerant of chronic hydrocarbon pollution. However, due to the incidence of mortality after exposure to diesel and oils Mytilus edulis was regarded as of intermediate intolerance to hydrocarbon contamination.
Suchanek (1993) noted that gastropods, amphipods, infaunal polychaetes and bivalves were particularly sensitive to oil spills. For example, substantial kills of Nereis, Cerastoderma, Macoma, Arenicola and Hydrobia were reported after the Sivand oil spill in the Humber (Hailey, 1995). The toxicity of oil and petrochemicals to fish ranges from moderate to high (Cole et al., 1999). The mussel bed may benefit from a reduction in starfish, dog whelk and fish predation, however, the above evidence suggests that the associated community will be adversely affected by hydrocarbon contamination. Therefore a biotope intolerance of high has been recorded.
Recovery is probably dependant on Mytilus edulis recruitment and a recoverability of high has, therefore, been recorded (see additional information below).
Radionuclide contamination
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Insufficient information.
Changes in nutrient levels
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Moderate nutrient enrichment, especially in the form of organic particulates and dissolved organic material, is likely to increase food availability for all the suspension feeders within the biotope. Therefore, 'not sensitive*' has been recorded. However, long term or high levels of organic enrichment may result in deoxygenation and algal blooms. Mytilus edulis has been reported to suffer mortalities due to algal blooms of Gyrodinium aureolum and Phaeocystis poucheri (Holt et al., 1998). Nucella lapillus has been shown to be severely affected by toxic algal blooms (see review; Robertson, 1991; Gibbs et al., 1999). Death of toxic and non-toxic algal blooms may result in large numbers of dead algal cells collecting on the sea bottom, resulting in local de-oxygenation as the algal decompose. Although, Mytilus edulis is probably tolerant of anoxic conditions other members of the community may be more intolerant (see oxygenation below).
Increase in salinity
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Mytilus edulis is considered to be tolerant of a wide range of salinities. Many members of the community occur in the intertidal and estuaries, exposed to fluctuating salinities. An increase from reduced to full salinity is likely to result in a change in species composition, to include more fully marine species and increased species richness, while the mussel bed itself is likely to be little affected. Since the biotope is likely to be persist and species richness increase, not sensitive* has been recorded.
Decrease in salinity
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However, in the longer term (weeks) Mytilus edulis can acclimate to lower salinities (Almada-Villela, 1984; Seed & Suchanek, 1992; Holt et al., 1998). Almada-Villela (1984) reported that the growth rate of individuals exposed to only 13psu reduced to almost zero but had recovered to over 80% of control animals within one month. Mytilus edulis can survive a considerably reduced salinities, growing as dwarf individuals at 4-5 psu in the Baltic. Asterias rubens is thought to be intolerant of salinity change, although local adaptation can occur (Stickle & Diehl, 1987), and a sudden inflow of river water into an inshore coastal area caused mass mortality of the conspecific species Asterias vulgaris at Prince Edward Island, Canada (Smith, 1940, in Lawrence, 1995). Asterias rubens would probably be excluded from the biotope by a further reduction in salinity.
Crothers (1985) noted that Nucella lapillus is usually absent from estuaries and although found in the Severn Estuary it is restricted to the lower shore up-channel from Minehead where they presumably avoid reduced salinities. Many of the infaunal species are probably tolerant of estuarine conditions, while other would be replaced by species, e.g. oligochaetes, tolerant of low salinities.
Overall, a reduction in salinity from variable to reduced is likely to reduce growth and productivity of the mussel beds but reduce predation pressure so that although species richness will be reduced, the biotope will probably remain. However, sudden acute changes in salinity from variable to low may result in loss of proportions of the mussel bed. Therefore, an intolerance of intermediate has been recorded. Recovery will probably be rapid (see additional information below).
Changes in oxygenation
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Mytilus edulis was regarded to be tolerant of a wide range of oxygen concentrations including zero (Zwaan de & Mathieu, 1992; Diaz & Rosenberg, 1995; see species review). Intolerance to hypoxia is variable. Echinoderms such as Asterias rubens are highly intolerant of anoxic conditions. Similarly, the barnacle Balanus crenatus was considered to be highly intolerant of anoxia (see review). Crustacea are probably intolerant of hypoxia but would be able to migrate to more suitable condition. However, most polychaetes are capable of anaerobic respiration and Capitella capitata, Hediste diversicolor and Scoloplos armiger were considered to be resistant of moderate hypoxia while Nephtys hombergii and Heteromastus filiformis were thought to be resistant of severe hypoxia (Diaz & Rosenberg, 1995). Therefore, Mytilus edulis is likely to tolerate hypoxic conditions. However, hypoxia is likely to cause species specific mortality and reduce species richness, an intolerance of intermediate. Recoverability of the associated species is likely to be rapid (see additional information below).

Biological Factors

Introduction of microbial pathogens/parasites
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The diseases and parasites of Mytilus edulis were reviewed by Bower (1992) and Bower & McGladdery (1996) (see the species review).
The boring sponge Cliona spp. has been reported from Modiolus modiolus beds and may affect subtidal Mytilus edulis beds. Similarly, subtidal beds may be affected by the boring polychaete Polydora ciliata. Both of the above boring species weaken the shell of the victim and makes them more vulnerable to predation. Polydora ciliata also causes blisters, atrophy of muscle tissue and interferes with gamete production and has resulted in substantial mortalities in European mussel populations. Asterias rubens may be parasitised by the ciliate Orchitophyra stellarum (Vevers, 1951; Bouland & Clareboudt, 1994) resulting in castration of males, and subsequent reduction in population size (Vevers, 1951). Nucella lapillus may also suffer form castration due to infestation with the larval stages of seabird trematode parasites.
None of the above were reported to cause high mortalities so that the biotope would probably persist. Therefore, an intolerance of low and a recoverability of very high has been recorded (see additional information below).
Introduction of non-native species
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Mytilus edulis is an effective space occupier and few other species are able to out-compete it for space. However, the South American mytilid Aulocomya ater has been reported recently in the Moray Firth, Scotland in 1994 and again in 1997 (McKay, 1994; Holt et al., 1998; Eno et al., 2000). Aulocomya ater is thought to have a stronger byssal attachment than Mytilus edulis and may replace Mytilus edulis in more exposed areas if it reproduces successfully (Holt et al., 1998). However, its potential effects in sheltered sedimentary habitats are unknown.
Extraction
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Large mussel beds in the intertidal and subtidal have been routinely fished for hundreds of years, and managed by local Sea Fishery Committees in England and Wales for the past hundred years (Holt et al., 1998).
Subtidal mussel beds may be exploited by dredging. Holt et al., (1998) suggest that, in particular embayments, over-exploitation may reduce subsequent recruitment leading to long term reduction in the population or stock. The relationship between stock and recruitment is poorly understood. Loss of stock may have significant effects on other species, e.g. in the Dutch Wadden Sea in 1990 the mussel stocks fell to unprecedented low levels resulting in death or migration of eiders, and oystercatchers seeking alternative prey such as Cerastoderma edule, Mya arenaria, and Macoma baltica.
Extraction of Mytilus edulis is likely to remove much of the epifaunal and infaunal community, resulting in a decline in species richness. Overall, an intolerance of intermediate has been recorded at the benchmark level of extraction. However, recovery is likely to occur within 5 years and a recoverability of high has been recorded (see additional information below).

Additional information icon Additional information

Recoverability
Larval supply and settlement could potentially occur annually, however, settlement is sporadic with unpredictable pulses of recruitment (Lutz & Kennish, 1992; Seed & Suchanek, 1992).
Mytilus edulis is highly fecund but larval mortality is high. Larval development occurs within the plankton over ca one month (or more), therefore, whilst recruitment within the population is possible, it is likely that larval produced within the biotope are swept away from the biotope to settle elsewhere. Therefore, recovery is probably dependant on recruitment from outside the biotope.
While good annual recruitment is possible, recovery may take at least 5 years. However, it should be noted that in certain circumstances and under some environmental conditions recovery may take significantly longer. Overall, Mytilus spp. populations were considered to have a strong ability to recover from environmental disturbance (Holt et al., 1998; Seed & Suchanek, 1992).
Polychaetes, oligochaetes and other interstitial fauna will probably recolonize rapidly (see recruitment processes), for example Boström & Bonsdorff (2000) reported that large numbers of nematodes, oligochaetes, chironomids, copepods, and the polychaete Pygospio elegans colonized artificial seagrass beds within 33-43 days. Recruitment in Asterias rubens is sporadic and larval production by one population may influence settlement some considerable distance away (Morgan, 1995), while not affecting the original population, so consequently it may take more than one or two generations for a population to return to a pre-impact state. However, recolonization is also likely to occur due to migration of adults or juveniles. Populations of Nucella lapillus appear to be capable of recovering with about 2-5 years if survivors are present either intertidally on below low water (see review) However, should a population need to recruit from surrounding area recovery may take significantly longer.

This review can be cited as follows:

2001. Mytilus edulis beds on variable salinity infralittoral mixed sediment. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 20/04/2014]. Available from: <http://www.marlin.ac.uk/habitatbenchmarks.php?habitatid=36&code=1997>