Biodiversity & Conservation

CR.MCR.ByH.Urt

Explanation of sensitivity and recoverability


Physical Factors

Substratum Loss
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Removal of the substratum will result in removal of all the sessile attached species, together with most of the slow mobile species (crustaceans, sea urchins and starfish) and an intolerance of high has been recorded. Recoverability will depend on recruitment from neighbouring communities and subsequent recovery of the original abundance of species, which may take many years, especially in slow growing sponges, Anthozoa and Flustra foliacea. Therefore, a recoverability of moderate has been recorded (see additional information below).
Smothering
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£MCR.Urt.Cio£ is characteristic of areas subject to cover by coarse sediment. Holme & Wilson (1985) reported communities that were subject to periodic smothering by thin layers of sand, up to ca 5cm in the central English Channel. Flustra foliacea and hydroids such as Nemertesiaspp. and the anemone Urticina felina were noted in their sand scoured communities which may have included examples of £MCR.Urt.Cio£. Smothering with a layer of sediment will prevent or reduce feeding and hence growth and reproduction.

Although the biotope will probably survive smothering at the benchmark level, the species richness of the biotope will probably decline due to the loss of more sensitive species due to clogging of their filtration apparatus, interrupted feeding and hence reduced growth, and potential short term anoxia under the sediment layer. Also, associated small species such as prosobranchs, amphipods and worms may be sensitive. Therefore, an intolerance of intermediate is suggested to reflect the reduced species richness. Recoverability is likely to be high (see additional information below) as the long-lived, slow growing species (Ciocalypta penicillus and Urticina felina) will most likely survive).

Increase in suspended sediment
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This biotope is characteristic of areas subject to sediment scour and therefore suspended sediment. While an increase in suspended sediment at the benchmark level for a month is likely to reduce the efficiency of filter feeding in some species (e.g. sponges, hydroids, soft corals and bryozoans), most species are likely to survive for a month. If there is an associated increase in siltation, it is likely to interfere with larval settlement if it coincided with the reproductive season. Therefore, an intolerance of low has been recorded.
Decrease in suspended sediment
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£MCR.Urt.Cio£ is characteristic of areas subject to sediment scour and suspended sediment. Therefore, with decreasing suspended sediment levels, species richness is likely to increase. A decrease in suspended sediment may decrease food availability for the duration of the benchmark (one month) but otherwise not adversely affect the biotope in such a short period of time. Therefore, an intolerance of low has been recorded. Prolonged decreases in suspended sediment, and consequent reduced scour may allow other species to colonize the habitat and out-compete characterizing species, perhaps increasing dominance by ascidians, sponges or anemones, and their biotopes. In such a situation, the biotope would no longer be £MCR.Urt.Cio£ and intolerance would be high.
Desiccation
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Sponges, hydroids, and soft corals, are probably highly intolerant of desiccation. However, this biotope is circalittoral and unlikely to be exposed to the air and desiccation.
Increase in emergence regime
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An increase or decrease in tidal emergence is unlikely to affect circalittoral habitats, except that the influence of wave action may be increased (see wave action below).
Decrease in emergence regime
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An increase or decrease in tidal emergence is unlikely to affect circalittoral habitats, except that the influence of wave action may be increased (see wave action below).
Increase in water flow rate
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£MCR.Urt.Cio£ is characterized by species that are tolerant of moderately strong to strong tidal streams and associated sediment scour. Increased water flow is likely to reduce predation by Asterias rubens and large sea urchins, e.g. Echinus esculentus was observed to be rolled along the substratum by currents of 2.6 knots or above (Comely & Ansell, 1988). But in severe scour, the community may become impoverished, consisting of Pomatoceros spp., encrusting bryozoans, encrusting coralline algae and Balanus crenatus, e.g. £ECR.PomByC£. The likely associated scour and displacement of some species in the biotope over the year (see benchmark), is likely to change the biotope to a different one. Therefore, an intolerance of high has been recorded. Recoverability is likely to be moderate (see additional information below).
Decrease in water flow rate
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£MCR.Urt.Cio£ is characterized by species that are tolerant of moderately strong to strong tidal streams and associated sediment scour. However, it is also typical of wave exposed situations. Although strong water movement is most likely required to prevent build-up of silty sediments that might smother the rocks on which the community occurs, wave action will continue to provide that water movement. Water movement is also important for suspension feeders such as hydroids, bryozoans, sponges, amphipods and ascidians to supply adequate food, remove metabolic waste products, prevent accumulation of sediment and disperse larvae or medusae. A decrease in water flow from e.g. moderately strong to very weak will only result in smothering of the community and/or decrease in supply of suspended food if wave action is low. During prolonged periods of calm weather, absence of strong tidal flow may allow siltation to occur and some damage to species may follow so that an intolerance of low has been suggested. Recoverability is likely to be rapid.
Increase in temperature
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£MCR.Urt.Cio£ is recorded from the southwest of Britain and Ireland suggesting that characteristic species at least include a significant warm water element. It therefore seems likely that increase in temperature in the short-term will not adversely affect the biotope and, in the long-term, might enable extension of distribution of the biotope and possibly increase in species richness. However, while not likely to be adversely affected by long term change, Urticina felina and Echinus esculentus are probably intolerant of short term increases in temperature at the benchmark level. Circalittoral habitats are probably protected from extreme changes in temperature by their depth in enclosed areas. Overall, the effects of increased temperature are likely to be favourable to the biotope.
Decrease in temperature
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The majority of the dominant or characterizing species in £MCR.Urt.Cio£ are boreal in their distribution and occur to the north and to the south of the British Isles. However, some are south-western in distribution and the biotope is only recorded from southern locations. Although it is not expected that short-term decrease in temperature will adversely affect established individuals, low temperature may adversely influence growth and reproduction in many species of hydroids, bryozoans and ascidians and may reduce recruitment into the biotope (see species reviews). Therefore, an intolerance of low has been recorded but it is noted that a long-term decrease in temperature may result in loss of some characterizing species and the biotope may change to a different one.
Increase in turbidity
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An increase in turbidity is likely to result in a decrease in phytoplankton and macroalgal primary production, which may reduce food available to the suspension feeders within the community. As a result , growth rates and reproduction may be decreased, and some species may not be able to keep up with predation (e.g. see Gaulin et al., 1986). However, slow growing species such as the cushion sponges and Urticina felina typical of this community and can probably survive reductions in food availability for a year. Therefore, an intolerance of low has been recorded.
Decrease in turbidity
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A decrease in turbidity may increase phytoplankton and hence zooplankton productivity and potentially increase food availability. Increased light penetration may allow macroalgae to colonize deeper water. Macroalgae effectively compete for space and grow over and may smother fauna. Therefore, decreased turbidity may allow macroalgae to colonize the more shallow examples of this biotope, resulting in loss of a proportion of the biotope, although some members of the community are likely to survive even in the presence of macroalgae. The favourable effects of a potential increase in food supply are probably more important than overgrowth by macroalgae at shallow depths. Therefore a rank of not sensitive has been recorded.
Increase in wave exposure
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£MCR.Urt.Cio£ occurs in exposed or moderately wave exposed habitats.

The oscillatory flow generated by wave action is potentially more damaging than unidirectional flow but is attenuated with depth (Hiscock, 1983). Wave action is also important in causing mobilization of coarse sediments and subsequent scour. Whilst many of the species in the biotope are clearly tolerant of oscillatory water movement and scour, less flexible or weaker hydroids and bryozoans may be removed, e.g. Nemertesia ramosa. Increased wave action may decrease sea urchin and starfish predation, perhaps allowing larger, massive species (e.g. sponges and anemones) to increase in dominance. Therefore, it is likely that some species within the biotope, especially hydroids may be lost and an intolerance of intermediate has been recorded. Recoverability is likely to be high (see additional information below).

Decrease in wave exposure
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£MCR.Urt.Cio£ is found in situations of both strong wave action and strong tidal streams. However, occasional very strong wave action is probably most important in causing the scour conditions that seem to typify this biotope. A decrease in wave action may allow species not able to withstand scour, such as delicate hydroids, erect bryozoans, ascidians and encrusting sponges to increase in abundance. In the absence of strong wave action, sea urchin predation may also increase and hence encourage increased patchiness and species richness (Sebens, 1985; Hartnoll, 1998).

The sponges that typify the biotope are most likely long-lived and would not disappear in the short term. However, colonization by other species may alter the character of the biotope sufficiently that it is no longer £MCR.Urt.Cio£ and therefore an intolerance of high is recorded. On return to previous conditions, and providing that important but potentially long-lived characterizing species such as the cushion sponges remain, recoverability is expected to be high.

Noise
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Sponges, hydroids and bryozoans are unlikely to be sensitive to noise or vibration at the benchmark level. Mobile fish species may be temporarily scared away from the areas but few if any adverse effects on the biotope are likely to result.
Visual Presence
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Hydroid and bryozoan polyps or barnacle cirri may retract when shaded by potential predators, however the community is unlikely to be affected by visual presence. Mobile fish species may be temporarily scared away from the areas but few if any adverse effects on the biotope are likely to result.
Abrasion & physical disturbance
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The species that characterize this biotope are tolerant of sediment scour but may be damaged by the impact of a hard surface such as an anchor or dredge.
Erect epifaunal species are particularly vulnerable to physical disturbance. Hydroids and bryozoans are likely to be detached or damaged by bottom trawling or dredging (Holt et al., 1995) whilst the upper surfaces at least of cushion sponges may be ripped off. Veale et al. (2000) reported that the abundance, biomass and production of epifaunal assemblages decreased with increasing fishing effort. Colonies of ross (Pentapora fascialis) are likely to be particularly sensitive and will be broken by slight impact from a hard object. Hydroid and bryozoan matrices were reported to be greatly reduced in fished areas (Jennings & Kaiser, 1998 and references therein). Mobile gears also result in modification of the substratum, including removal of shell debris, cobbles and rocks, and the movement of boulders (Bullimore, 1985; Jennings & Kaiser, 1998). The removal of rocks or boulders to which species are attached results in substratum loss (see above). Species with fragile tests such as Echinus esculentus and the brittlestar Ophiocomina nigra and edible crabs Cancer pagurus were reported to suffer badly from the impact of a passing scallop dredge (Bradshaw et al., 2000). Scavengers such as Asterias rubens and Buccinum undatum were reported to be fairly robust to encounters with trawls (Kaiser & Spencer, 1995) and may benefit in the short term, feeding on species damaged or killed by passing dredges. However, Veale et al. (2000) did not detect any net benefit at the population level.

Overall, physical disturbance by an anchor or mobile fishing gear is likely to remove a proportion of all groups within the community and attract scavengers to the community in the short term. The characterizing species will be injured but not, in the main, lost. Therefore, an intolerance of intermediate has been recorded. Recoverability is likely to be high due to repair and regrowth of hydroids and bryozoans (e.g. Pentapora fascialis), and recruitment within the community from surviving colonies and individuals or parts of sponges and bryozoans left behind (see additional information below).
Displacement
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Most permanently fixed, sessile species, such as bryozoans (e.g. Pentapora fascialis and Bugula species), the cushion sponges and hydroids (e.g. Nemertesia species) cannot reattach to the substratum if removed, and may be damaged or destroyed in the process. Hydroids and sponges may be able to grow from fragments, aiding recovery. Mobile species, such as amphipods, gastropods, small crustaceans, crabs and fish are likely to survive displacement. Anemones (e.g. Urticina felina) are strongly but not permanently attached and will probably reattach to suitable substrata. However, the dominant, sponges, bryozoans and hydroids are likely to be lost and, since the cushion sponges are likely to recruit slowly, an intolerance of high has been recorded. Recolonization by cushion sponges and by Urticina felina may be slow and a recoverability of moderate has been recorded (see additional information below).

Chemical Factors

Synthetic compound contamination
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There is little information available on effects of chemicals on most of the main characterizing species in £MCR.Urt.Cio£. In particular, no information was found on sponges. However, bryozoans are common members of the fouling community, and amongst those organisms most resistant to antifouling measures, such as copper containing anti-fouling paints (Soule & Soule, 1979; Holt et al., 1995). Nevertheless, Hoare & Hiscock (1974) suggested that Polyzoa (Bryozoa) were amongst the most sensitive species to acidified halogenated effluents in Amlwch Bay, Anglesey, reported that Flustra foliacea did not occur less than 165m from the effluent source and noted that Bugula flabellata did not occur within the bay. Urticina felina survived near to the acidified halogenated effluent discharge in a 'transition' zone where many other species were unable to survive, suggesting a tolerance to chemical contamination but did not survive closer to the effluent source (Hoare & Hiscock, 1974).

The species richness of hydroid communities decreases with increasing pollution (Boero, 1984; Gili & Hughes, 1995).

Alcyonium digitatum at a depth of 16m in the locality of Sennen Cove (Pedu-men-du, Cornwall) died resulting from the offshore spread and toxic effect of detergents e.g. BP 1002 sprayed along the shoreline to disperse oil from the Torrey Canyon tanker spill (Smith, 1968). Possible sub-lethal effects of exposure to synthetic chemicals, may result in a change in morphology, growth rate or disruption of reproductive cycle. Smith (1968) also noted that large numbers of dead Echinus esculentus were found between 5.5 and 14.5 m in the vicinity of Sennen, presumably due to a combination of wave exposure and heavy spraying of dispersants in that area (Smith, 1968). Smith (1968) also demonstrated that 0.5 -1ppm of the detergent BP1002 resulted in developmental abnormalities in echinopluteus larvae of Echinus esculentus.

Tri-butyl tin (TBT) has a marked effect on numerous marine organisms (Bryan & Gibbs, 1991). The encrusting bryozoan Schizoporella errata suffered 50% mortality when exposed for 63 days to 100ng/l TBT. Bryan & Gibbs (1991) reported that virtually no hydroids were present on hard bottom communities in TBT contaminated sites and suggested that some hydroids were intolerant of TBT levels between 100 and 500 ng/l. Copepod and mysid crustaceans were particularly intolerant of TBT while crabs were more resistant (Bryan & Gibbs, 1991), although recent evidence suggests some sublethal endocrine disruption in crabs. Rees et al. (2001) reported that the abundance of epifauna had increased in the Crouch estuary in the five years since TBT was banned from use on small vessels. Rees et al. (2001) suggested that TBT inhibited settlement in ascidian larvae. This report suggests that epifaunal species (including, bryozoan, hydroids and ascidians) may be at least inhibited by the presence of TBT.

Therefore, hydroids crustaceans, gastropods, and ascidians are probably intolerant of TBT contamination while bryozoans are probably intolerant of other chemical pollution and an intolerance of intermediate has been recorded, albeit at low confidence. Assuming that sponges (which are likely to be long-lived and slow to recruit) are not sensitive, a recoverability of high has been recorded (see additional information below).
Heavy metal contamination
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No studies have been found which investigate the effects of heavy metals on the main characterizing species (Cushion sponges, Urticina felina especially) in £MCR.Urt.Cio£. Various heavy metals have been show to have sublethal effects on growth in the few hydroids studied experimentally (Stebbing, 1981; Bryan, 1984; Ringelband, 2001). Bryozoans are common members of the fouling community and amongst those organisms most resistant to anti-fouling measures, such as copper containing anti-fouling paints.

Bryozoans were also shown to bioaccumulate heavy metals to a certain extent (Soule & Soule, 1979; Holt et al., 1995).

Echinus esculentus populations in the vicinity of an oil terminal in A Coruna Bay, Spain, showed developmental abnormalities in the skeleton and their tissues contained high levels of aliphatic hydrocarbons, naphthalenes, pesticides and heavy metals (Zn, Hg, Cd, Pb, and Cu) (Gomez & Miguez-Rodriguez 1999). Waters containing 25 µg / l Cu caused developmental disturbances in Echinus esculentus (Kinne, 1984) and heavy metals caused reproductive anomalies in the starfish Asterias rubens (Besten, et al., 1989, 1991). Sea urchin larvae have been used in toxicity testing and as a sensitive assay for water quality (reviewed by Dinnel et al. 1988), so that echinoderms are probably intolerant of heavy metal contamination. Gastropod molluscs have been reported to relatively tolerant of heavy metals while a wide range of sublethal and lethal effects have been observed in larval and adult crustaceans (Bryan, 1984).

Therefore, an intolerance of low has been recorded to represent the sublethal effects on dominant bryozoans and hydroids. Loss of predatory sea urchins, may result in an increased dominance by some species and a slight decrease in species richness. Overall, without information on the intolerance of the most abundant characterizing species, an assessment cannot be made.

Hydrocarbon contamination
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£MCR.Urt.Cio£ is likely to be protected from the direct effects of oil spills by its circalittoral occurrence but may be exposed to emulsified oil treated with dispersants, especially in areas of turbulence, or exposed to water soluble fractions of oils, PAHs or oil adsorbed onto particulates. For example:
  • Species of the encrusting bryozoan Membranipora and the erect bryozoan Bugula were reported to be lost or excluded from areas subject to oil spills. (Mohammad, 1974; Soule & Soule, 1979). Houghton et al. (1996) also reported a reduction in the abundance of intertidal encrusting bryozoans (no species given) at oiled sites after the Exxon Valdez oil spill.
  • The water soluble fractions of Monterey crude oil and drilling muds were reported to cause polyp shedding and other sublethal effects in the athecate hydroid Tubularia crocea in laboratory tests (Michel & Case, 1984; Michel et al., 1986; Holt et al., 1995).
  • Suchanek (1993) reported that the anemones Anthopleura spp. and Actinia spp. survived in waters exposed to spills and chronic inputs of oils. Similarly, one month after the Torrey Canyon oil spill the dahlia anemone, Urticina felina, was found to be one of the most resistant animals on the shore, being commonly found alive in pools between the tide-marks which appeared to be devoid of all other animals (Smith, 1968).
  • Amphipods, especially ampeliscid amphipods, are regarded as especially sensitive to oil (Suchanek, 1993).
  • Smith (1968) reported dead colonies of Alcyonium digitatum at depth in the locality of Sennen Cove (Pedu-men-du, Cornwall) resulting from the combination of wave exposure and heavy spraying of dispersants along the shoreline to disperse oil from the Torrey Cannon tanker spill (see synthetic chemicals).
  • Crude oil from the Torrey Canyon and the detergent used to disperse it caused mass mortalities of echinoderms; Asterias rubens, Echinocardium cordatum, Psammechinus miliaris, Echinus esculentus, Marthasterias glacialis and Acrocnida brachiata (Smith, 1968). Echinus esculentus populations in the vicinity of an oil terminal in A Coruna Bay, Spain, showed developmental abnormalities in the skeleton. The tissues contained high levels of aliphatic hydrocarbons, naphthalenes, pesticides and heavy metals (Zn, Hg, Cd, Pb, and Cu) (Gomez & Miguez-Rodriguez 1999).
  • Halichondria panicea survived in areas affected by the Torrey Canyon oil spill, although few observations were made (Smith 1968).
If the physiology within different animals groups can be assumed to be similar, then bryozoans, amphipods, echinoderms and soft corals may be intolerant of hydrocarbon contamination, while hydroids may demonstrate sublethal effects and anemones and some species of sponge are relatively tolerant. Some members of the bryozoan turf and some members of the community may be lost or damaged as a result of acute hydrocarbon contamination, although a recognisable biotope may remain. Assessment of intolerance can only be made for a proportion of the community species and therefore a confidence of very low is indicated. Therefore, an intolerance of intermediate has been suggested, albeit at very low confidence. Recoverability is likely to be high (see additional information below).
Radionuclide contamination
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No information found.
Changes in nutrient levels
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An increase in nutrient levels from e.g. sewage sludge, sewage effluent or riverine flooding, may result in an increase in inorganic and organic suspended particulates (see above), increased turbidity (see above) and increased phytoplankton productivity. Moderate nutrient enrichment may increase the food available to the community in the form of phytoplankton, zooplankton or organic particulates. However, eutrophication may result in increased algae and deoxygenation (see below). While the biotope is unlikely to be directly affected by algal blooms, the biotope may be adversely affected by toxins from toxic algae that accumulate in zooplankton, or smothered by dead 'bloom' algae and deoxygenation resulting form their subsequent decay (see below). Death of a bloom of the phytoplankton Gyrodinium aureolum in Mounts Bay, Penzance in 1978 produced a layer of brown slime on the sea bottom. This resulted in the death of invertebrates, including Echinus esculentus, Marthasterias glacialis, while sessile bryozoans, sponges and Alcyonium spp. appeared moribund, presumably due to anoxia caused by the decay of the dead dinoflagellates (Griffiths et al. 1979). This biotope occurs in areas subject to moderately strong to strong tidal streams, so that prolonged deoxygenation is unlikely to occur. However, an intolerance of low has been recorded to represent the potential toxic effects of the algae and the siltation caused by death of an algal bloom.
Increase in salinity
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This biotope occurs in full salinity and is unlikely to encounter increases in salinity.
Decrease in salinity
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Most of the species identified as indicative of intolerance are of 'intermediate' or 'low' intolerance to a reduction in salinity. However, some of the main characterizing species especially cushion sponges are not generally found in low salinity situations, perhaps because of wave shelter rather than salinity reduction. It is concluded that a decrease in salinity may result in mortality of some of the species in the biotope and an intolerance of intermediate has been recorded. Assuming that likely slow growing and low recruitment species such as the cushion sponges will be adversely affected, a recoverability of moderate is suggested.
Changes in oxygenation
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This biotope occurs in areas subject to moderately strong to strong tidal streams, so that deoxygenating conditions are unlikely to develop.

Biological Factors

Introduction of microbial pathogens/parasites
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No information has been found.
Introduction of non-native species
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No non-native species currently known from Britain and Ireland are known to occur in £MCR.Urt.Cio£ and so 'not relevant' is recorded. Intolerance in the future would depend on the nature of new non-native arrivals.
Extraction
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It is extremely unlikely that any of the species indicative of sensitivity would be targeted for extraction and we have no evidence for the indirect effects of extraction of other species on this biotope.

Additional information icon Additional information

Recoverability
Where local populations exist or remain after disturbance, recruitment is likely to be rapid for many species including regrowth from any remaining fragments of species such as Ciocalypta penicillus and Pentapora fascialis. Some others, such as Pomatoceros triqueter and Balanus crenatus are likely to settle rapidly after loss. In studies of subtidal epifaunal communities in New England, Sebens (1985, 1986) reported that cleared areas were colonized by erect hydroids, bryozoans, crustose red algae and tube worms within 1-4 months in spring, summer and autumn. Some species will take longer. For instance, Alcyonium sp. colonized within 4 years.

Flustra foliacea is slow growing, long-lived and new colonies take at least 1 year to develop erect growth and 1-2 years to reach maturity (Stebbing, 1971a; Eggleston, 1972a), depending on environmental conditions. Four years after sinking, the wreck of a small coaster, the M.V. Robert, off Lundy was found to be colonized by erect bryozoans and hydroids, including occasional small Pentapora fascialis (Hiscock, 1981). The wreck was several hundreds of metres from any significant hard substrata, and hence a considerable distance from potentially parent colonies (Hiscock, 1981 and pers. comm.). Pentapora fascialis is noted as having good reproductive and recolonization abilities, quite fast growth rates and gaining reproductive competency at an early stage (Cocito et al., 1998(b)).

However, no information has been found about the reproduction and recolonization potential of Ciocalypta penicillus and other cushion sponges (species of Polymastia) which may be slow. Also, recovery of Urticina felina is likely to be slow in populations where nearby individuals do not exist. The large size, slow growth rate and evidence from aquarium populations suggests that Urticina felina is long lived. Although it probably breeds each year there is no information regarding fecundity. Breeding probably does not occur until the anemone is at least 1.5 years old. Dispersal ability is considered to be poor in the similar Urticina eques (Solé-Cava et al., 1994). The larva is most likely benthic and, although unlikely to settle for many days after release (based on work on the similar Tealia crassicornis for north-west USA), is unlikely to travel far. Adults can detach from the substratum and relocate but locomotive ability is very limited. In view of the likelihood that two of the main characterizing species are unlikely to recover former abundance rapidly following catastrophic loss of the biotope, a recoverability of moderate is identified in those circumstances.


This review can be cited as follows:

Hiscock, K. 2002. Urticina felina on sand-affected circalittoral rock. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 21/10/2014]. Available from: <http://www.marlin.ac.uk/habitatbenchmarks.php?habitatid=290&code=1997>