Biodiversity & Conservation

SS.CMS._.AfilEcor

Explanation of sensitivity and recoverability


Physical Factors

Substratum Loss
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Most species in the CMS.AfilEcor biotope are infaunal or epifaunal and will be lost if the substratum is removed so the overall intolerance of the biotope is high. Although there are some mobile species in the biotope, such as the polychaete Nephtys hombergii, they are not very fast moving and so are also likely to be removed. The key species do not reach sexual maturity for several years. For example, it takes approximately 5-6 years for Amphiura filiformis to grow to maturity and about 3 years for Echinocardium cordatum. However, it has been observed that subtidal populations of Echinocardium cordatum appear never to reach sexual maturity (Buchanan, 1967) and recruitment is often sporadic, with reports of the species recruiting in only 3 years over a 10 year period (Buchanan, 1966). Intertidal individuals reproduce more frequently so recruitment may be dependent on intertidal populations. The burrowing mud shrimp reaches sexual maturity within the first year, possibly breeding twice a year and producing planktonic larvae so recovery is expected to be rapid. Immigration of adult mud shrimps can also aid recovery. The remaining megafauna in the biotope vary in their longevity and reproductive strategies and some species will reach sexual maturity very rapidly. However, as the key species take a long time to reach sexual maturity it seems likely that a community of Amphiura filiformis and Echinocardium cordatum may take longer than five years to recover and so a rank of moderate is reported.
Smothering
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The biotope will have low intolerance to smothering by 5 cm of sediment because most species are burrowing and live within the sediment anyway. Amphiura filiformis lives within the top 3-4 cm of sediment and Echinocardium cordatum and Callianassa subterranea create burrows in the sediment and many other species in the biotope are also infaunal. There may be an energetic cost expended to either re-establish burrow openings, to self-clean feeding apparatus or to move up through the sediment though this is not likely to be significant. Most animals will be able to reburrow or move up through the sediment within hours or days so recovery is set at immediate. Intolerance to smothering by other factors such as oil may be higher.
Increase in suspended sediment
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Most species in the biotope are burrowing infauna so will not be affected by an increase in suspended sediment. There may be possible clogging of the feeding organs of the suspension feeding sea pens although since these animals are able to self-clean this is not likely to be very energetically costly, particularly at the level of the benchmark. Some species may benefit from increased food supply if suspended sediment has a high organic content. However, since most species in the biotope have low intolerance to an increase in suspended sediment at the benchmark level an overall rank of low is also reported for the biotope. Overall species composition and richness is not expected to be affected. On return to normal suspended sediment levels recovery will be immediate as affected species will be able to self-clean within a few days.
Decrease in suspended sediment
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A decrease in suspended sediment and siltation will reduce the flux of particulate material to the seabed. Since this includes organic matter the supply of food to the biotope would probably also be reduced. However, the benchmark is a reduction in suspended sediment of 100mg/l for a month which is unlikely to have a significant effect on the biotope and would not alter species composition. Intolerance is therefore, assessed as low. On return to normal conditions recovery will be rapid and a rank of very high is recorded.
Desiccation
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The biotope only occurs in the circalittoral zone (below 10 m) and is not subject to desiccation.
Increase in emergence regime
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The biotope only occurs in the circalittoral zone (below 10 m) and is not subject to a change in emergence regime.
Decrease in emergence regime
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The biotope only occurs in the circalittoral zone (below 10 m) and is not subject to a change in emergence regime.
Increase in water flow rate
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The biotope is generally found in areas of weak or very weak tidal streams and so is likely to be intolerant of increases in water flow. However, in Scottish sea lochs, Howson et al. (1994) also found the biotope in areas of moderately strong tidal streams. Tidal currents keep most of the organic particles in the sediment in suspension which can support suspension feeders such as Amphiura filiformis even in low organic content sediments. The horizontal supply of small and light nutritious particles by resuspension and advective transport has been shown to influence the growth rate of suspension-feeding benthos (Dauwe, 1998). As a suspension feeder without any self-produced feeding current water flow rate will be of primary importance to Amphiura filiformis. Individuals respond rapidly to currents by extending their arms vertically to feed. Under laboratory conditions they were shown to maintain this vertical position at currents of 30 cm/s (approx. 0.6 knots) (Buchanan, 1964). If water movement were to increase to strong (3-6 knots), individuals would be unlikely to maintain this position and so would retract their arms. Other suspension feeders in the biotope will also be unable to feed if the water flow rate increases by two categories in the water flow scale (see benchmarks). The sea pen Virgularia mirabilis, for example, would be unable to feed in water flow increased by the benchmark level. A long term increase (i.e. the benchmark level of one year) will change the nature of the top layers of sediment, becoming coarser and possibly unsuitable for some shallow burrowing species such as the brittle stars Amphiura. High density aggregations of Amphiura filiformis seem to be characteristic of fine sediments with silt/clay values of 10 to 20% (O'Connor et al., 1983) so removal of the finer matter is likely to reduce abundance. In more exposed and coarser sediments Amphiura filiformis may be replaced by Amphiura brachiata that may change the nature of the biotope because A. brachiata is a suspension, rather than deposit feeder. Deeper burrowing species such as the thalassinidean crustaceans Callianassa subterranea are not likely to be affected by sediment changes at the surface. The overall impact of an increase in water flow rate on the biotope may be the loss of some key species, such as Amphiura filiformis, which changes the biotope, and some other species such as sea pens so intolerance is assessed as high. Recovery is moderate - see additional information.
Decrease in water flow rate
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Amphiura filiformis shows a lack of activity in still water and low current speeds can impede feeding because it may reduce the transport of organic particles. Therefore, if water flow rate changes by the benchmark level of two categories for a year feeding would be significantly impaired and viability of the population reduced. Over the period of a year many individuals would be likely to die so intolerance is assessed as high. In slightly less energetic conditions and finer sediment, the biotope CMU.SpMeg, which includes high abundance of sea pens and burrowing megafauna such as Callianassa subterranea, is more likely to be present. For recovery see additional information.
Increase in temperature
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The key species Amphiura filiformis and Echinocardium cordatum have a relatively wide degree of tolerance to temperature in accordance with their cosmopolitan distribution. Both species are distributed in warmer waters to the south of Britain and Ireland and most sediment species will be subject to annual variations in temperature of about 10 °C. Therefore, CMS.AfilEcor may be tolerant of long term increases although growth and fecundity of some species may be affected. In Echinocardium cordatum for example, there is rapid growth in the summer and no growth in the winter (Ridder de et al., 1991) and generally higher growth rates in warmer waters (Duineveld & Jenness, 1984). Muus (1981) showed that juvenile Amphiura filiformis are capable of much higher growth rates in experiments with temperatures between 12 and 17 °C. However, Amphiura filiformis and other animals live subtidally where wide and rapid variations in temperature, such as experienced in the intertidal do not occur. Therefore the biotope may be more intolerant of a short term increase of 5 °C and so a rank of intermediate is recorded. For most deep burrowing species like Callianassa subterranea temperature changes in the water column are likely to be buffered to some extent by the sediment and so many individuals will not be affected.
Decrease in temperature
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The key species Amphiura filiformis and Echinocardium cordatum have a relatively wide degree of tolerance to temperature in accordance with their cosmopolitan distribution. Both species are distributed in waters to the north of Britain and Ireland and so are probably able to tolerate long term decreases in temperature. In British waters most sediment species will be subject to annual variations in temperature of about 10 °C. Therefore, CMS.AfilEcor may be tolerant of long term increases although growth and fecundity of some species may be affected. However species may be less tolerant of short term decreases. Echinoderms, including Amphiura filiformis, of the North Sea seem periodically affected by winter cold with mortalities during cold waters. Low temperatures are a limiting factor for breeding which takes place during the warmest months in the UK. Very low water temperature can also cause mass mortalities of Echinocardium cordatum. During the severe winter of 1963 the species was almost completely eliminated from the German Bight to a depth of about 20 m (Lawrence, 1996) and very heavy mortality was observed in the English Channel and North Sea (Crisp (ed.), 1964). The intolerance of the biotope is set at intermediate as some individuals of the key species may be lost during short term decreases in extreme cold weather.
Increase in turbidity
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An increase in turbidity, reducing light availability may reduce primary production by phytoplankton in the water column. However, productivity in the CMS.AfilEcor biotope is secondary (detritus) and although an increase in turbidity may reduce phytoplankton contribution to detritus any effects, at the level of the benchmark, are not likely to be significant and so intolerance is assessed as low. On return to normal conditions recovery is likely to be very high as increased light results in more photosynthetic productivity and improved food supply.
Decrease in turbidity
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A decrease in turbidity, increasing light availability may improve primary production by phytoplankton in the water column. However, productivity in the CMS.AfilEcor biotope is secondary (detritus) and although a decrease in turbidity may raise phytoplankton contribution to detritus any effects, at the level of the benchmark, are not likely to be significant and so intolerance is assessed as low. On return to normal conditions recovery is likely to be very high.
Increase in wave exposure
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The key species, Amphiura filiformis and Echinocardium cordatum are found in sheltered habitats characterized by fine muddy sandy sediments and low wave exposure. Both species are likely to be intolerant of increases in wave exposure. Strong wave action can re-suspend the sediment and break up and scatter Amphiura filiformis although the species is able to burrow further into the sediment and if displaced is able to reburrow. Nevertheless, intolerance to wave exposure at the benchmark level is likely to be high because the species would probably not survive the disturbance for a period of a year. Echinocardium cordatum is typically a sheltered shore species although in coastal waters of the Netherlands the species occurs in the tidal zone on some sandflats exposed to wave-action, at the entrances of the Oosterschelde and the Westerschelde (Wolff, 1968). In the bay of Douarnenez, Brittany Echinocardium cordatum was only found in areas of fine sand dominated by high sediment instability, due to marked exposure to westerly swells (Guillou, 1985). However, the species is unlikely to survive in areas of extreme wave exposure and is recorded as having intermediate intolerance. The intolerance of the biotope is assessed as high because of the probable loss of the key structuring species, Amphiura filiformis. Recolonization within five years should be possible as recolonization can take place from recruitment of larvae and juveniles and also immigration of adults from unaffected areas but the community is not likely to return to the original profile within five years because Amphiura filiformis does not reach sexual maturity until 5-6 years. Recovery has therefore, been assessed as moderate.
Decrease in wave exposure
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The biotope occurs in areas of very low or no wave exposure such as sea lochs so a reduction in wave exposure is not likely to have a significant impact on the biotope and so intolerance is assessed as low. If a decrease in wave exposure were also combined with a decrease in water flow rate deoxygenation may occur to which some species in the biotope would be intolerant.
Noise
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Some of the important characterizing species associated with this biotope, such as Amphiura filiformis, may respond to sound vibrations and will retract their arms into the sediment. Feeding will resume once the disturbing factor has passed. However, none of the characterizing species are especially intolerant of noise disturbance at the level of the benchmark such as boats etc. passing overhead and so the biotope is recorded as being not sensitive.
Visual Presence
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Most species within the biotope are burrowing and have no or poor visual perception and are unlikely to be affected by visual disturbance such as shading. Epifauna such as crabs have well developed visual acuity and are likely to respond to movement in order to avoid predators. However, it is unlikely that the species will be affected by visual disturbance at the benchmark level. The biotope is therefore reported as not sensitive to the factor.
Abrasion & physical disturbance
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The biotope is not generally subject to anthropogenic physical disturbance because it does not support any commercial species. Consequently, there is little information on effects of physical disturbance on the CMS.AfilEcor community. However, there is information on individual species. Echinocardium cordatum, for example, has a fragile test that is likely to be damaged by an abrasive force such as movement of trawling gear over the seabed. A substantial reduction in the numbers of the species due to physical damage from scallop dredging has been observed (Eleftheriou & Robertson, 1992). Echinocardium cordatum was reported to suffer between 10 and 40% mortality due to fishing gear, depending on the type of gear and sediment after a single trawl event (Bergman & van Santbrink, 2000). They suggested that mortality may increase to 90% in summer when individuals migrate to the surface of the sediment during their short reproductive season. Bergman & van Santbrink (2000) suggested that Echinocardium cordatum was one of the most vulnerable species to trawling.

Bergman & Hup (1992) for example, found that beam trawling in the North Sea had no significant direct effect on small brittle stars. Brittlestars can tolerate considerable damage to arms and even the disk without suffering mortality and are capable of arm and even some disk regeneration. The intolerance of Amphiura filiformis to abrasion and physical disturbance is recorded as low. Individuals can still function whilst regenerating a limb so recovery will be rapid. In an analysis of long-term effects of scallop dredging on benthic communities in the Irish Sea, Bradshaw et al. (2002) noted a decline in the sedentary, filter feeding brittlestars Ophiothrix fragilis and Ophiopholis aculeata but an increase in surface detritivores or scavenging brittlestars such as Amphiura filiformis, Ophiocomina nigra and Ophiura albida. Ramsay et al. (1998) suggest that Amphiura spp. may be less susceptible to beam trawl damage than other species like echinoids or tube dwelling amphipods and polychaetes.

The factor is not relevant to Callianassa subterranea because the species rarely leaves its burrows under normal circumstances and burrows are deep enough, sometimes up to 80 cm, to avoid trawls and dredges. Thus physical disturbance like trawling is unlikely to affect Callianassa subterranea to any great extent. Other species, also found in this biotope, that were observed to be sensitive include the bivalves Nucula nitidosa and Corbula gibba and the polychaetes Nephtys sp. and Terebellides stroemi. For epifaunal species, no long-term effects on the total number of species or individuals were detected, but individual species did show effects, notably an increase in the density of Ophiura sp. and a decrease in numbers of the fish Hippoglossoides platessoides and the whelk Buccinum undatum. Other authors have also suggested that increases in echinoderm populations in the North Sea are associated with fishing disturbance (Aronson, 1990; Lindley et al., 1995). Therefore, the overall effect on the biotope would be a reduction in species diversity and the loss of a number of individuals of the key species Echinocardium cordatum so the intolerance of the biotope is reported to be intermediate. Recovery of Echinocardium cordatum should be possible within five years so a rank of high is reported.

Displacement
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Most species in the biotope are burrowing and have low intolerance to displacement, such as that caused by a passing trawl that does not kill species but throws them into suspension, because animals can reburrow into suitable substrata. Displaced individuals of Amphiura filiformis that are not damaged (see Abrasion above) can right themselves if displacement caused them to be inverted and they can rapidly re-burrow into the sediment as can Echinocardium cordatum. Sea pens such as Virgularia mirabilis will re-burrow (Jones et al., 2000) and recover completely within 72 hours after displacement, provided the basal peduncle remains in contact with the sediment surface. Burrowing crustaceans such as Callianassa subterranea can reburrow immediately although full burrow construction may take longer. Infaunal organisms that move through the sediment but do not construct permanent burrows, like errant polychaetes will return to the sediment after displacement. Therefore, provided individuals are not damaged most species within the biotope are able to rapidly re-burrow after displacement so intolerance is assessed as low and recovery will be immediate.

Chemical Factors

Synthetic compound contamination
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There was no information found on the effect of chemical pollutants on the biotope. However, effects on some of the individual species in the biotope have been reported from which impacts on the biotope can be extrapolated. Dahllöf et al. (1999) studied the long term effects of tri-butyl-tin (TBT) on the function of a marine sediment system. TBT spiked sediment was added to sediment that already had a TBT background level of approximately 27ng g-1 (83 pmol TBT /g) and contained the following fauna: Amphiura spp., Brissopsis lyrifera and several species of polychaete. Within two days of treatment with a TBT concentration above 13.7 µmol / m2 all species except the polychaetes had crept up to the surface and after six weeks these fauna had started to decay. Thus, increased contamination from TBT is likely to result in the death of some intolerant species such as brittle stars and heart urchins. Echinocardium cordatum was also found to be highly intolerant of detergents used to disperse oil from the Torrey Canyon oil spill which caused mass mortalities of the species (Smith, 1968). Thus, the key species seem to be highly intolerant of some chemical pollutants and may be lost from the biotope. Loss of the key species means loss of the biotope so intolerance is assessed as high. On return to normal conditions recovery may take many years and recovery is reported to be moderate - see additional information.
Heavy metal contamination
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In Norwegian fjords, Rygg (1985) found a relationship between species diversity in benthic fauna communities and sediment concentrations of heavy metals Cu, Pb and Zn. Cu in particular showed a strong negative correlation and the author suggested a cause-effect relationship. Those species not present at sites where Cu concentrations were greater than ten times higher than the background level, such as Amphiura filiformis and several bivalves including Nucula sulcata were assessed as non-tolerant species. The tolerant species were all polychaete worms. Therefore, increased heavy metal contamination in sediments may change the faunal composition of the community and decrease overall species diversity. Some burrowing crustaceans, brittle stars and bivalves may disappear from the biotope and lead to an increasing dominance of polychaetes.
Hydrocarbon contamination
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There was no information found on the effect of hydrocarbon pollution on the biotope. The best documented oil spill for protected habitats with soft mud/sand substrates is the West Falmouth, Florida spill of 1969. Immediately after the spill virtually the entire benthic fauna was eradicated immediately following the incident and populations of the opportunistic polychaete Capitella capitata increased to abundances of over 200,000/m² (Sanders, 1978). The key species in the biotope, Amphiura filiformis and Echinocardium cordatum and also Callianassa subterranea are very intolerant of hydrocarbon pollution and so the intolerance of the biotope is recorded as high. Mass mortality of Echinocardium cordatum, down to about 20m, was observed shortly after the Amoco Cadiz oil spill (Cabioch et al., 1978). However, oil from spills would have to be dispersed deep into the water column to affect the biotope and since the biotope occurs in very sheltered conditions this is unlikely to occur. However, the key species in the biotope have been observed to be intolerant of chronic oil pollution. For example, reduced abundance of Echinocardium cordatum was detectable up to > 1000m away one year after the discharge of oil-contaminated drill cuttings in the North Sea (Daan & Mulder, 1996). Callianassa subterranea also appears to be highly intolerant of sediment contaminated by oil-based drilling muds (Daan et al., 1992) and in a study of the effects of oil exploration and production on benthic communities Olsgard & Gray (1995) found Amphiura filiformis to be very intolerant of oil pollution. Oil polluted sediments may remain so for many years so recovery may be protracted. For example, persistent toxicity of Amoco Cadiz oil in sediment prevented the start of the recovery period (Clark, 1997). On return to normal conditions recovery may take many years because of the life-history of the key species. Recovery is recorded to be moderate - see additional information for rationale.
Radionuclide contamination
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Investigations of bioturbation in radionuclide contaminated sediments close to the Sellafield nuclear processing plant in the Irish Sea indicate that the burrowing mud shrimp Callianassa subterranea has some tolerance to radionuclide pollution (Hughes & Atkinson, 1997). However, the impact on the key species in the biotope, Amphiura filiformis and Echinocardium cordatum, is unknown and the sensitivity of the biotope cannot be assessed.
Changes in nutrient levels
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In places where oxygen concentrations are still sufficiently high, the suspension feeding Amphiura filiformis reacts positively to organic enrichment in terms of increasing abundance and biomass (Josefson & Smith, 1984; Rosenberg et al., 1987). Callianassa subterranea also has low intolerance to increases in the organic content of the sediment However, Echinocardium cordatum has higher intolerance to increased nutrients where the effect is a reduced mean individual weight (Josefson, 1990). Pearson & Rosenberg (1976) describe the changes in fauna along a gradient of increasing organic enrichment by pulp fibre where Echinocardium cordatum is absent from all but distant sediments with low organic input. Typically an increasing gradient of organic enrichment results in a decline in the suspension feeding fauna and an increase in the number of deposit feeders, in particular polychaete worms, so other species are also likely to disappear in increasing nutrients. Therefore, an increase in nutrients at the benchmark level of a 50% increase is likely to result in reduced viability and abundance of Echinocardium cordatum and the possible loss of the less tolerant species so intolerance is assessed as intermediate. Echinocardium cordatum reaches sexual maturity within 3 years. It has been observed that subtidal populations of Echinocardium cordatum appear never to reach sexual maturity (Buchanan, 1967) and recruitment is often sporadic, with reports of the species recruiting in only 3 years over a 10 year period (Buchanan, 1966). However, intertidal individuals reproduce more frequently and the settling larva is not thought to be very substratum selective so recruitment should be possible within five years. The burrowing mud shrimp reaches sexual maturity within the first year, possibly breeding twice a year and producing planktonic larvae so recovery is expected to be rapid. Immigration of adult mud shrimps can also aid recovery. The remaining megafauna in the biotope vary in their longevity and reproductive strategies and some species will reach sexual maturity very rapidly. Thus, recovery of the biotope should be possible within five years and so a rank of high is reported.
Increase in salinity
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The biotope is found in fully marine sublittoral conditions that do not experience water evaporation such as seen in rock pools in the intertidal or in lagoons. Therefore, it seems likely that the biotope will be intolerant of increases in salinity. The overall effect on the biotope of a chronic increase in salinity for a period of a year is likely to be the loss of most species and so intolerance is reported as high. On return to normal conditions recovery to previous community profile is likely to take several years - see additional information.
Decrease in salinity
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The biotope is found in fully marine conditions and does not extend into estuaries so is likely to be intolerant of decreases in salinity. The key species in the biotope are highly intolerant of salinity changes and although Echinocardium cordatum has been observed in brackish conditions marine populations are likely to be intolerant of a long term, chronic decrease; e.g., a change of one category from the MNCR salinity scale for one year. The overall effect on the biotope of a chronic decrease in salinity for a period of a year is likely to be the loss of most species and so intolerance is reported as high.
Changes in oxygenation
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Amphiura filiformis and Callianassa subterranea are tolerant of reduced oxygen concentrations and would not be significantly affected by the benchmark level of 2 mg/l for a week. However, the spatangoid urchin Echinocardium cordatum is highly intolerant of a fall in oxygenation. In the south-eastern North Sea a period of reduced oxygen resulted in the death of many individuals of Echinocardium cordatum (Niermann, 1997) and in laboratory experiments many individuals were dead at a concentration of 2.4mg/l (Nilsson & Rosenberg, 1994). Other species in the biotope will have varying responses to deoxygenation. Rosenberg et al. (1991) suggests that some part of the benthic community, including Amphiura filiformis, can withstand oxygen concentrations of around 1mg/l for several weeks. However, with a loss of the key species Echinocardium cordatum the biotope will also be lost so intolerance is assessed as high. Echinocardium cordatum reaches sexual maturity within three years, reproduces every year and has pelagic larvae so recovery should be possible within five years and a rank of high is reported. Individuals can also migrate from unaffected areas. The time for re-establishment of faunal biomass after a period of anoxia related mortality in the south-eastern North Sea was 2 years (Niermann, 1997).

Biological Factors

Introduction of microbial pathogens/parasites
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There is little information on microbial pathogen effects on the characterizing species in this biotope. The occurrence of several parasitic gregarine protozoans, such as Urospora neapolitana, have been observed in the body cavity of Echinocardium cordatum (Coulon & Jangoux, 1987). However, no information concerning infestation or disease related mortalities was found. No evidence of losses of this biotope due to disease were found and a rank of low has been reported. However, other species have been affected by disease so there is always the potential for this to occur.
Introduction of non-native species
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There are no records of any non-native species invading the biotope and so is assessed as not sensitive. However, as several species have become established in British waters there is always the potential for this to occur.
Extraction
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It is unlikely that the biotope would be subject to extraction as it has no commercial and limited research value although dredging operations may remove populations in some habitats if the burrowing crustacean Nephrops norvegicus is present. There is not a great deal of dependency in the species present and therefore extraction of one would not radically change the function of the biotope. However, with the loss of a key species, after which the biotope is named, the species composition of the biotope would be significantly different. An important functional species in the biotope, Callianassa subterranea, would probably not be extracted even if dredging, or similar, operations were to take place because it lives within burrow systems that may extend up to 80 cm or more. However, the species has important consequences for sedimentary characteristics such as bioturbation and oxygenation as well as creating habitats for other species to colonize so its removal may affect the overall species composition of the biotope. Nevertheless, the species is not present in very high abundance so a significant impact on the biotope. Intolerance is assessed as intermediate although recovery is expected to be high (see additional information).

Additional information icon Additional information

Recoverability
They key species do not reach sexual maturity for several years. For example, it takes approximately 5-6 years for Amphiura filiformis to grow to maturity and about 3 years for Echinocardium cordatum. However, it has been observed that subtidal populations of Echinocardium cordatum appear never to reach sexual maturity (Buchanan, 1967) and recruitment is often sporadic, with reports of the species recruiting in only 3 years over a 10 year period (Buchanan, 1966). Intertidal individuals reproduce more frequently so recruitment may be dependent on intertidal populations. The burrowing mud shrimp reaches sexual maturity within the first year, possibly breeding twice a year and producing planktonic larvae so recovery is expected to be rapid. Immigration of adult mud shrimps can also aid recovery. The remaining megafauna in the biotope vary in their longevity and reproductive strategies and some species will reach sexual maturity very rapidly. However, as the key species take a long time to reach sexual maturity it seems likely that a community of Amphiura filiformis and Echinocardium cordatum may take longer than five years to recover and so a rank of moderate is reported.

This review can be cited as follows:

Hill, J.M. 2004. Amphiura filiformis and Echinocardium cordatum in circalittoral clean or slightly muddy sand. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 21/11/2014]. Available from: <http://www.marlin.ac.uk/habitatbenchmarks.php?habitatid=368&code=1997>