Philine aperta and Virgularia mirabilis in soft stable infralittoral mud

02-01-2005
Researched byJacqueline Hill & Emily Wilson Refereed byDr David Hughes
EUNIS CodeA5.343 EUNIS NamePhiline aperta and Virgularia mirabilis in soft stable infralittoral mud

Summary

UK and Ireland classification

EUNIS 2008A5.343Philine aperta and Virgularia mirabilis in soft stable infralittoral mud
EUNIS 2006A5.343Philine aperta and Virgularia mirabilis in soft stable infralittoral mud
JNCC 2004SS.SMu.IFiMu.PhiVirPhiline aperta and Virgularia mirabilis in soft stable infralittoral mud
1997 BiotopeSS.IMU.MarMu.PhiVirPhiline aperta and Virgularia mirabilis in soft stable infralittoral mud

Description

Physically very stable muds with a high proportion of fine material (greater than 80 %) may contain the sea pen Virgularia mirabilis. These muds typically occur in shallow water to about 12-15 m where significant seasonal variation in temperature is presumed to occur. This habitat is restricted to the most sheltered basins in, for example, sea lochs. Although most records suggest full salinity conditions are prevalent, some sites may be subject to variable salinity. The opisthobranch Philine aperta is the most characteristic species of this habitat, occurring in high densities at many sites. The sea pen Virgularia mirabilis, a species found more widely in muddy sediments, appears to reach its highest densities in this shallow mud. Other conspicuous species found in this shallow muddy habitat include Cerianthus lloydii, Sagartiogeton spp., Ascidiella aspersa and Myxicola infundibulum. Amphiura chiajei and Amphiura filiformis may also be present at some sites. Burrowing crustacean megafauna, characteristic of deeper mud, are rare or absent from this shallow sediment. Of these burrowers Nephrops norvegicus may sometimes be recorded. The bivalves Nucula sp., Thyasira flexuosa and Corbula gibba may be other conspicuous infaunal species. The sediment may be covered by a diatom film. In the south of Great Britain, the polychaete Sternaspis scutata is also characteristic of this biotope. This polychaete is rare in Great Britain (Sanderson 1996). Indeed, this southern variant of the biotope is very restricted in the UK to Portland Harbour but is known to occur further south in the Gulf of Gascony and the Mediterranean (Glemarec 1973; Dauvin et al. 1994). Similar but deeper more stable muds to IMU.PhiVir are characterized by burrowing megafauna (CMU.SpMeg). IMU.PhiVir has a lot of similarity with CMU.BriAchi, possibly differing on account of low disturbance or linkage with enriched overlying waters, however, these hypotheses are untested. IMU.PhiVir may also be closely allied to CMS.AbrNucCor, showing some of the infaunal elements of this biotope. (Information taken from the Marine Biotope Classification for Britain and Ireland, Version 97.06: Connor et al., 1997a, b).

Recorded distribution in Britain and Ireland

In the UK this biotope is almost confined to the most sheltered basins of certain sea lochs, with one further example known from Portland Harbour in southern England.

Depth range

5-10 m, 10-20 m

Additional information

-

Listed By

Further information sources

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JNCC

Habitat review

Ecology

Ecological and functional relationships

  • The characterizing and other species in this biotope occupy space in the habitat but their presence is most likely primarily determined by the occurrence of a suitable substratum rather by interspecific interactions. Virgularia mirabilis and Philine aperta are functionally dissimilar and are not necessarily associated with each other but occur in the same muddy sediment habitats. There is no information regarding possible interactions between any of the other species in the biotope but there seems to little interdependence. Burrowing species which are present create tunnels in the sediment which themselves provide a habitat for other burrowing or inquilinistic species.
  • Virgularia mirabilis might be adversely affected by high levels of megafaunal bioturbation, perhaps by preventing the survival of newly settled colonies.
  • Many of the species living in deep mud biotopes are generally cryptic in nature and not usually subject to predation. Evidence of predation on Virgularia mirabilis by fish seems limited to a report by Marshall & Marshall (1882 in Hoare & Wilson, 1977) where the species was found in the stomach of haddock. Many specimens of Virgularia mirabilis lack the uppermost part of the colony which has been attributed to nibbling by fish. Observations by Hoare & Wilson (1977) suggest however, that predation pressure on this species is low. The sea slug Armina loveni is a specialist predator of Virgularia mirabilis.
  • Nephrops norvegicus is known to be eaten by a variety of bottom-feeding fish, including cod, haddock, skate and dogfish. Symbion pandora, a tiny sessile animal less than 1 mm long, lives commensally on the mouthparts of Nephrops norvegicus.
  • Brittlestars are common, with Amphiura chiajei predominating on finer muds. Most of these animals are deposit-feeders, ingesting tiny organic particles and feeding on the bacterial layer coating the sediment grains. If present in high abundance the burrowing and feeding activities of Amphiura chiajei can modify the fabric and increase the mean particle size of the upper layers of the substrata by aggregation of fine particles into faecal pellets. Such actions create a more open fabric with a higher water content which affects the rigidity of the seabed (Rowden et al., 1998(b)). Such destabilisation of the seabed can affect rates of particle resuspension.
  • The hydrodynamic regime, which in turn controls sediment type, is the primary physical environmental factor structuring benthic communities such as IMU.PhiVir. The hydrography also affects the water characteristics in terms of salinity, temperature and dissolved oxygen. It is also widely accepted that food availability (see Rosenberg, 1995) and disturbance, such as that created by storms, (see Hall, 1994) are also important factors determining the distribution of species in benthic habitats.

Seasonal and longer term change

  • Species such as the sea pen Virgularia mirabilis and Amphiura chiajei appear to be long-lived and are unlikely to show any significant seasonal changes in abundance or biomass. Seapen faunal communities appear to persist over long periods at the same location. Movement of the sea pen Virgularia mirabilis in and out of the sediment may be influenced by tidal conditions (Hoare & Wilson, 1977).
  • The numbers of some of the other species in the biotope may show peak abundances at certain times of the year due to seasonality of breeding and larval recruitment.

Habitat structure and complexity

The biotope has very little structural complexity with most species living in or on the sediment. Burrowing megafauna are generally rare or absent, therefore there will be few burrows available for colonization. Several species, such as the sea pen Virgularia mirabilis and the anemone Cerianthus lloydii, extend above the sediment surface. However, apart from a couple of species of nudibranch living on the sea pens and the tubiculous amphipod Photis longicaudata associated with Cerianthus lloydii (Moore & Cameron, 1999) these species do not provide significant habitat for other fauna. Excavation of sediment by infaunal organisms, such as errant polychaetes and Philine aperta, ensures that sediment is oxygenated to a greater depth allowing the development of a much richer and/or higher biomass community of species within the sediment.

Productivity

Productivity in subtidal sediments is often quite low. Macroalgae are absent from IMU.PhiVir and so productivity is mostly secondary, derived from detritus and organic material. Allochthonous organic material is derived from anthropogenic activity (e.g. sewerage) and natural sources (e.g. plankton, detritus). Autochthonous organic material is formed by benthic microalgae (microphytobenthos e.g. diatoms and euglenoids) and heterotrophic micro-organism production. Organic material is degraded by micro-organisms and the nutrients are recycled.

Recruitment processes

  • Philine aperta, Virgularia mirabilis and other major component species in sea pen biotopes appear to have a plankton stage within their life cycle.
  • The reproductive biology of British sea pens has not been studied, but in other species, for instance Ptilosarcus guerneyi from Washington State in the USA, the eggs and sperm are released from the polyps and fertilization takes place externally. The free-swimming larvae do not feed, and settle within seven days if a suitable substratum is available (Chia & Crawford, 1973). Dispersal of Virgularia mirabilis planulae is therefore likely to be limited to relatively short distances suggesting that populations may not be replenished from distant sources (David Hughes, pers. comm.). The limited data available from other species would suggest a similar pattern of patchy recruitment, slow growth and long life-span for Virgularia mirabilis.

Time for community to reach maturity

Very little is known about the population dynamics and longevity of Virgularia mirabilis in Britain, however information from other species suggest that this species is likely to be long-lived and slow growing with patchy and intermittent recruitment. Other burrowing species representative of this biotope vary in longevity and reproductive strategies.

Additional information

No text entered

Preferences & Distribution

Recorded distribution in Britain and IrelandIn the UK this biotope is almost confined to the most sheltered basins of certain sea lochs, with one further example known from Portland Harbour in southern England.

Habitat preferences

Depth Range 5-10 m, 10-20 m
Water clarity preferences
Limiting Nutrients Nitrogen (nitrates), Phosphorus (phosphates)
Salinity Full (30-40 psu)
Physiographic Enclosed coast / Embayment
Biological Zone Infralittoral
Substratum Mud
Tidal Very Weak (negligible)
Wave Extremely sheltered, Very sheltered
Other preferences

Additional Information

This biotope can be found in water less than 10 m deep in the sheltered inner basins of some sea lochs (Howson et al., 1994)

Species composition

Species found especially in this biotope

    Rare or scarce species associated with this biotope

    • Sternapsis scutata

    Additional information

    May contain the nationally rare polychaete Sternapsis scutata in southern Great Britain.

    Sensitivity reviewHow is sensitivity assessed?

    Explanation

    Philine aperta and Virgularia mirabilis are the main important characterizing species, giving the name to the biotope. Amphiura filiformis is an important species as it represents the burrowing brittlestars that are found within this biotope.

    Species indicative of sensitivity

    Community ImportanceSpecies nameCommon Name
    Important otherAmphiura filiformisA brittlestar
    Important characterizingPhiline apertaA sea slug
    Important characterizingVirgularia mirabilisA sea pen

    Physical Pressures

     IntoleranceRecoverabilitySensitivitySpecies RichnessEvidence/Confidence
    High Moderate Moderate Major decline Low
    The important characterizing species associated with this biotope rank high to substratum loss as they are infaunal, burrowing species. Philine aperta has fast growth and reproductive rates and could recolonize from other areas as the species is common. Very little is known about the population dynamics and longevity of Virgularia mirabilis in Britain, however information from other species suggest that this species is likely to be slow growing with patchy and intermittent recruitment. Therefore, full recovery of this biotope and the important characterizing species will take many years.
    Intermediate Moderate Moderate Minor decline Low
    Species within the biotope are able to deal with small and temporary increases in silt deposition as they have the ability to self-clean. Depositions of thick silt, however, are likely to smother individuals to an extent where they are unable to self-clean or dig out and may also leave a substratum unsuitable for recolonization. Philine aperta has fast growth and reproductive rates and could recolonize from other areas as the species is common. Very little is known about the population dynamics and longevity of Virgularia mirabilis in Britain, however information from other species suggest that this species is likely to be slow growing with patchy and intermittent recruitment. Therefore, full recovery of this biotope and the important characterizing species will take many years and so a rank of moderate is reported.
    Low Very high Very Low No change Low
    The dominant trophic groups associated with this biotope are suspension feeders and deposit feeders. Suspension of fine silt and clay fractions of the sediment resulting from activities such as dredging may clog feeding structures. Effects, however, are uncertain. Species within the biotope are able to deal with small and temporary increases in silt as they have the ability to self-clean.
    Not relevant Not relevant Not relevant Not relevant Not relevant
    This biotope is found in the infralittoral zone and so not likely to be affected by desiccation. The important characterizing species, if exposed to air, are likely to be highly intolerant.
    Not relevant Not relevant Not relevant Not relevant Not relevant
    This biotope is found in the infralittoral zone and so not likely to be affected by emergence. The important characterizing species, if exposed to air, are likely to be highly intolerant.
    Not sensitive* Not relevant
    The biotope is found in the infralittoral zone so a decrease in emergence is not relevant.
    High High Moderate Minor decline Low
    The biotope is only found in areas of weak or very weak tidal streams and so is likely to be intolerant of increases in water flow. Some tidal flow is necessary for the horizontal supply of small and light nutritious particles by resuspension and advective transport, influencing the growth rate of suspension-feeding benthos (Dauwe, 1998). However, some suspension feeders in the biotope will 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, will retract into the sediment at water currents speeds greater than 0.5m/s (i.e. 1 knot) (Hiscock, 1983). If water speeds remain at this level or above, sea-pens will be unable to extend above the sediment, will be unable to feed and will probably die. The sea slug Philine aperta, which lives on the surface of the sediment, and the deposit feeding Amphiura chiajei would probably be washed away by strong water movement. Therefore, a long term increase in water flow rates would probably result in the loss of many of the key species, and hence the biotope, so intolerance is reported to be high.
    The biotope exists in habitats such as sea lochs, where tidal streams are already very weak so a decrease in flow rate would result in almost non-moving water. In these enclosed or semi-enclosed water bodies, negligible water flow may result in some deoxygenation of the overlying water and the loss of some intolerant species. The sea pen Virgularia mirabilis for example, has high intolerance to deoxygenation and may die. Tidal currents keep most of the organic particles in the sediment in suspension which can support suspension feeders even in low organic content sediments. Therefore, if water movement becomes negligible suspended organic particles available to filter feeders such as the sea pens will decline. Growth and fecundity will be affected and over a period of a year may result in the death of sea pens. The overall impact on the biotope is likely to be the loss of a few key species such as sea pens and so intolerance is assessed as high. Recovery would probably take longer than five years and so is assessed as moderate - see additional information below for rationale.
    No information No information No information Insufficient
    information
    Low
    Insufficient
    information
    Tolerant Not relevant Not relevant No change Low
    Philine aperta is a burrowing species and Virgularia mirabilis is insensitive to light therefore an increase or decrease in light levels caused by changing turbidity levels will have little or no effect on the biotope and associated species. Nephrops norvegicus is most active at night in shallow depths and during the day in deep water, suggesting that a particular level of light is of some importance.
    Low Very high Very Low Minor decline Low
    This biotope is associated with low-energy conditions and so is unlikely to be effected by wave exposure. If wave exposure increased Philine aperta can burrow and Virgularia mirabilis, if uprooted, can reburrow provided suitable substratum remains for recolonization.
    Tolerant Not relevant Not relevant No change Low
    The important characterizing species associated with this biotope respond to sound vibrations and can retract into the sediment. Feeding will resume once the disturbing factor has passed.
    Tolerant Not relevant Not relevant No change Low
    The important characterizing species associated with this biotope have limited visual perception and therefore unlikely to be sensitive to visual presence.
    Intermediate Moderate Moderate Minor decline Low
    The important characterizing species associated with this biotope can retract into the sediment and displaced individuals that are not damaged will reburrow. Virgularia mirabilis is able to retract into the sediment and so some individuals may be able to avoid some forms of abrasion or physical disturbance. Sea pens retract slowly and are likely to be sensitive to abrasion by trawling for instance, which is likely to break the rachis of Virgularia mirabilis. Species obtained by dredges were invariably damaged (Hoare & Wilson, 1977). However, the densities of Virgularia mirabilis were similar in trawled and untrawled sites in Loch Fyne and no changes in sea pen density was observed after experimental trawling over a 18 month period in another loch (Howson & Davies, 1991; Tuck et al. , 1998; Hughes, 1998). Hughes (1998) concluded that Virgularia mirabilis and Pennatula phosphorea, which can withdraw into the sediment, were probably less susceptible to the effects of damage by fishing gear than Funiculina quadrangularis, which is unable to withdraw. In an investigation into the effect of shellfish traps on benthic habitats (Eno et al. , 1996), creels were dropped on sea pens and left for extended periods to simulate the effects of smothering which could occur during commercial operations. The sea pens consistently righted themselves following removal of the pots. However, predation may increase and the viability of a population may be reduced whilst regeneration occurs. Philine aperta is soft bodied and likely to be damaged or displaced by a passing scallop dredge.

    Overall, a proportion of the species populations are likely to be lost and an intolerance of intermediate has been recorded. For recoverability, see additional information below.

    Low Very high Very Low Minor decline Low
    The important characterizing species associated with this biotope have the ability to reburrow, provided they have not been damaged. However, predation risk is increased whilst individuals are reburrowing.

    Chemical Pressures

     IntoleranceRecoverabilitySensitivityRichnessEvidence/Confidence
    No information No information No information Insufficient
    information
    Not relevant
    Fine sediments associated with this biotope are ideal for accumulation of pollutants and bioturbation by burrowing organisms may help to redistribute them. Suspension feeders have the ability to accumulate pollutants, however, effects are uncertain.
    Heavy metal contamination
    No information No information No information Insufficient
    information
    Not relevant
    Fine sediments associated with this biotope are ideal for accumulation of pollutants and bioturbation by burrowing organisms may help to redistribute them. Suspension feeders have the ability to accumulate pollutants, however, effects are uncertain.
    Hydrocarbon contamination
    No information No information No information Insufficient
    information
    Not relevant
    Fine sediments associated with this biotope are ideal for accumulation of pollutants and bioturbation by burrowing organisms may help to redistribute them. Suspension feeders have the ability to accumulate pollutants, however, effects are uncertain.
    Radionuclide contamination
    No information Not relevant No information Insufficient
    information
    Not relevant
    Fine sediments associated with this biotope are ideal for accumulation of pollutants and bioturbation by burrowing organisms may help to redistribute them. Suspension feeders have the ability to accumulate pollutants, however, effects are uncertain.
    Changes in nutrient levels
    No information Not relevant No information Insufficient
    information
    Not relevant
    Nutrient enrichment would have an impact most likely through resultant hypoxia (low oxygen concentrations).
    High Moderate Moderate No change Low
    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 are highly intolerant of salinity changes although Jones et al. (2000) suggest that Virgularia mirabilis appears to be somewhat tolerant of occasional lowering of salinity.
    Intermediate High Low Minor decline Low
    Well oxygenated water is required for burrowing species associated with this biotope. Sea pen faunal communities are absent from areas which are de-oxygenated and characterized by a distinctive bacterial community. Therefore they are likely to be highly intolerant of anoxia and hypoxia may result in reduced viability of species populations such as Amphiura filiformis. Philine aperta has fast growth and reproductive rates and could recolonize from other areas as the species is common. Very little is known about the population dynamics and longevity of Virgularia mirabilis in Britain, however information from other species suggest that this species is likely to be slow growing with patchy and intermittent recruitment. Therefore, full recovery of this biotope and the important characterizing species will take many years.

    Biological Pressures

     IntoleranceRecoverabilitySensitivityRichnessEvidence/Confidence
    No information No information No information Insufficient
    information
    Not relevant
    Insufficient
    information
    No information No information No information Insufficient
    information
    Not relevant
    Insufficient
    information
    Intermediate Moderate Moderate Minor decline Low
    It is extremely unlikely that any of the species indicative of sensitivity would be targeted for extraction. However, fishing for Nephrops norvegicus may lead to exploitation of the biotope. The important characterizing species associated with this biotope can retract into the sediment and displaced individuals that are not damaged will reburrow. Virgularia mirabilis is able to retract into the sediment and so some individuals may escape damage from the trawl. Sea pens retract slowly and are likely to be sensitive to abrasion by trawling for instance, which is likely to break the rachis of Virgularia mirabilis. Species obtained by dredges were invariably damaged (Hoare & Wilson, 1977). However, the densities of Virgularia mirabilis were similar in trawled and untrawled sites in Loch Fyne and no changes in sea pen density was observed after experimental trawling over a 18 month period in another loch (Howson & Davies, 1991; Tuck et al. , 1998; Hughes, 1998). Hughes (1998) concluded that Virgularia mirabilis and Pennatula phosphorea, which can withdraw into the sediment, were probably less susceptible to the effects of damage by fishing gear than Funiculina quadrangularis, which is unable to withdraw. In an investigation into the effect of shellfish traps on benthic habitats (Eno et al., 1996), creels were dropped on sea pens and left for extended periods to simulate the effects of smothering which could occur during commercial operations. The sea pens consistently righted themselves following removal of the pots. However, predation may increase and the viability of a population may be reduced whilst regeneration occurs. Philine aperta is soft bodied and likely to be damaged or displaced by a passing scallop dredge.

    Overall, a proportion of the species populations are likely to be lost and an intolerance of intermediate has been recorded. For recoverability, see additional information below.

    Intermediate High Low No change Low

    Additional information

    Recoverability
    No evidence on community development was found. Very little is known about the population dynamics and longevity of Virgularia mirabilis in Britain. However, information from other species suggest that this species is likely to be slow growing with patchy and intermittent recruitment and so recovery from loss of this species is likely to longer than five years. Philine aperta is thought to live for 3-4 years and spawns egg masses, which release pelagic larvae, for several months between the spring and summer so recovery is likely to fairly rapid. Individuals can also migrate in from outside areas. However, since one the key species, Virgularia mirabilis may not recover from loss within a five year period, the recovery rank for the biotope is set to moderate.

    Importance review

    Policy/Legislation

    Habitats Directive Annex 1Large shallow inlets and bays
    UK Biodiversity Action Plan Priority

    Exploitation

    • The fine sediments on which this biotope typically exists is not targeted for seabed extraction. Divers generally are not attracted to sedimentary habitats and so there is no likelihood of environmental damage by this means.
    • However, fishing for Nephrops norvegicus may lead to exploitation of the biotope. If trawls are used to extract Nephrops the biotope is likely to be significantly damaged as sea pens may be killed and Philine aperta and other species damaged or killed. However, creeling for Nephrops is unlikely to cause significant damage (Eno et al., 1996).

    Additional information

    -

    Bibliography

    1. Chia, F.S. & Crawford, B.J., 1973. Some observations on gametogenesis, larval development and substratum selection of the sea pen Ptilosarcus guerneyi. Marine Biology, 23, 73-82.
    2. Connor, D.W., Dalkin, M.J., Hill, T.O., Holt, R.H.F. & Sanderson, W.G., 1997a. Marine biotope classification for Britain and Ireland. Vol. 2. Sublittoral biotopes. Joint Nature Conservation Committee, Peterborough, JNCC Report no. 230, Version 97.06., Joint Nature Conservation Committee, Peterborough, JNCC Report no. 230, Version 97.06.
    3. Dauwe, B., Herman, P.M.J. & Heip, C.H.R., 1998. Community structure and bioturbation potential of macrofauna at four North Sea stations with contrasting food supply. Marine Ecology Progress Series, 173, 67-83.
    4. Eno, N.C., MacDonald, D. & Amos, S.C., 1996. A study on the effects of fish (Crustacea/Molluscs) traps on benthic habitats and species. Final report to the European Commission. Study Contract, no. 94/076.
    5. Hall, S.J., 1994. Physical disturbance and marine benthic communities: life in unconsolidated sediments. Oceanography and Marine Biology: an Annual Review, 32, 179-239.
    6. Hiscock, K., 1983. Water movement. In Sublittoral ecology. The ecology of shallow sublittoral benthos (ed. R. Earll & D.G. Erwin), pp. 58-96. Oxford: Clarendon Press.
    7. Hoare, R. & Wilson, E.H., 1977. Observations on the behaviour and distribution of Virgularia mirabilis O.F. Müller (Coelenterata: Pennatulacea) in Holyhead harbour. In Proceedings of the Eleventh European Symposium on Marine Biology, University College, Galway, 5-11 October 1976. Biology of Benthic Organisms, (ed. B.F. Keegan, P.O. Ceidigh & P.J.S. Boaden, pp. 329-337. Oxford: Pergamon Press. Oxford: Pergamon Press.
    8. Howson, C.M. & Davies, L.M., 1991. Marine Nature Conservation Review, Surveys of Scottish Sea Lochs. A towed video survey of Loch Fyne. Vol. 1 - Report. Report to the Nature Conservancy Council from the University Marine Biological Station, Millport.
    9. Howson, C.M., Connor, D.W. & Holt, R.H.F., 1994. The Scottish sealochs - an account of surveys undertaken for the Marine Nature Conservation Review. Joint Nature Conservation Committee Report, No. 164 (Marine Nature Conservation Review Report MNCR/SR/27)., Joint Nature Conservation Committee Report, No. 164 (Marine Nature Conservation Review Report MNCR/SR/27).
    10. Hughes, D.J., 1998b. Subtidal brittlestar beds. An overview of dynamics and sensitivity characteristics for conservation management of marine SACs. Natura 2000 report prepared for Scottish Association of Marine Science (SAMS) for the UK Marine SACs Project., Scottish Association for Marine Science. (UK Marine SACs Project, Vol. 3). Available from:  http://www.ukmarinesac.org.uk/publications.htm

    11. Jones, L.A., Hiscock, K. & Connor, D.W., 2000. Marine habitat reviews. A summary of ecological requirements and sensitivity characteristics for the conservation and management of marine SACs. Joint Nature Conservation Committee, Peterborough. (UK Marine SACs Project report.)., http://www.english-nature.org.uk/uk-marine
    12. Moore, P.G. & Cameron, K.S., 1999. A note on a hitherto unreported association between Photis longicaudata (Crustacea: Amphipoda) and Cerianthus lloydii (Anthozoa: Hexacorallia). Journal of the Marine Biological Association of the United Kingdom, 79, 369-370.
    13. Rosenberg, R., 1995. Benthic marine fauna structured by hydrodynamic processes and food availability. Netherlands Journal of Sea Research, 34, 303-317.
    14. Rowden, A.A., Jago, C.F. & Jones, S.E., 1998b. Influence of benthic macrofauna on the geotechnical and geophysical properties of surficial sediment, North Sea. Continental Shelf Research, 18, 1347-1363.
    15. Tuck, I.D., Hall, S.J., Robertson, M.R., Armstrong, E. & Basford, D.J., 1998. Effects of physical trawling disturbance in a previously unfished sheltered Scottish sea loch. Marine Ecology Progress Series, 162, 227-242.

    Citation

    This review can be cited as:

    Hill, J.M. & Wilson, E. 2005. Philine aperta and Virgularia mirabilis in soft stable infralittoral mud. In Tyler-Walters H. and Hiscock K. (eds) Marine Life Information Network: Biology and Sensitivity Key Information Reviews, [on-line]. Plymouth: Marine Biological Association of the United Kingdom. Available from: http://www.marlin.ac.uk/habitat/detail/202

    Last Updated: 02/01/2005