Ampharete falcata turf with Parvicardium ovale on cohesive muddy sediment near margins of deep stratified seas

23-07-2001
Researched byJacqueline Hill Refereed byThis information is not refereed.
EUNIS CodeA5.371 EUNIS NameAmpharete falcata turf with Parvicardium ovale on cohesive muddy sediment near margins of deep stratified seas

Summary

UK and Ireland classification

EUNIS 2008A5.371Ampharete falcata turf with Parvicardium ovale on cohesive muddy sediment near margins of deep stratified seas
EUNIS 2006A5.371Ampharete falcata turf with Parvicardium ovale on cohesive muddy sediment near margins of deep stratified seas
JNCC 2004SS.SMu.OMu.AfalPovaAmpharete falcata turf with Parvicardium ovale on cohesive muddy sediment near margins of deep stratified seas
1997 BiotopeCOS.COS.AmpParAmpharete falcata turf with Parvicardium ovale on cohesive muddy very fine sand near margins of deep stratified seas

Description

Dense stands of Ampharete falcata tubes which protrude from muddy sediments, appearing as a turf or meadow in localised areas. These areas seem to occur on a crucial point on a depositional gradient between areas of tide-swept mobile sands and quiescent stratifying muds. Dense populations of the small bivalve Parvicardium ovale occur in the superficial sediment. Both Amphiura filiformis and Amphiura chiajei may be present together with Nephrops norvegicus in higher abundance than the CMU.BriAchi or CMS.AfilEcor biotopes. Substantial populations of mobile epifauna such as Pandalus montagui and smaller fish also occur, together with those that can cling to the tubes, such as Macropodia spp. A similar turf of Melinna cristata, a maldanid worm, has been recorded from Northumberland (Buchanan, 1963). (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

Recorded from Loch Etive and the Irish Sea.

Depth range

-

Additional information

-

Listed By

Further information sources

Search on:

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 than by interspecific interactions. Ampharete falcata and Parvicardium ovale are functionally dissimilar and are not normally associated with each other but do occur in the same muddy sediment habitats. There is no information regarding possible interactions between any species in the biotope. In addition to Ampharete falcata and Parvicardium ovale the biotope supports several bivalve species and a fauna of burrowing species such as Amphiura filiformis, Amphiura chiajei, Nephrops norvegicus and smaller less conspicuous species such as errant polychaetes, nematodes etc.
  • The burrowing and feeding activities of Amphiura filiformis 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). 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 COS.AmpPar. 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

One of the key factors affecting benthic habitats is disturbance which in deep sediment habitats such as COS.AmpPar is minimal and so communities are often relatively stable. However, there may be some seasonal changes in the biotope such as recruitment of young, growth rates and abundance of adults. For example, growth rates of Parvicardium ovale are greatest in August (Rasmussen, 1973). The abundance of Ampharete acutifrons was observed to have seasonal variation with a peak in April, which had fallen by October to be followed by a new recruitment in spring of the next year (Price & Warwick, 1980).

Habitat structure and complexity

The biotope has very little structural complexity. On the surface of the sediment, the polychaete Ampharete falcata creates a turf of small tubes on the surface of muddy sediments in which some species, such as Macropodia spp. spider crabs, are able to live by clinging to the polychaete tubes. Within the sediment, burrowing species (for instance, Nephrops norvegicus) create habitats that cryptic species can use. Otherwise, the fauna uses the sediment for shelter without increasing structural complexity.

Productivity

Productivity in subtidal sediments is often quite low. Macroalgae are absent from COS.AmpPar 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. The high surface area of fine particles provides surface for microflora. Being confined to mud, the polychaete Ampharete falcata is probably susceptible to predation. A related species Ampharete acutifrons is the principal food of flounders in spring and summer so Ampharete falcata may be an important food source.

Recruitment processes

Recruitment and settlement of Parvicardium ovale normally takes place in July-August (Rasmussen, 1973). Ampharete falcata is thought to have a benthic larvae (Connor et al., 1997(a)) so that its dispersive capability is severely reduced. Time of recruitment is unknown although in a similar species, Ampharete acutifrons, recruitment of young takes place in the spring (Price & Warwick, 1980). In a study of Amphiura filiformis populations in Galway Bay over a period of 2 years O'Conner & McGrath (1980) were not able to identify discrete periods of recruitment. However, other studies suggest autumn recruitment (Buchanan, 1964) and spring and autumn (Glmarec, 1979). Using a 265µm mesh size Muus (1981) identified a peak settlement period in the autumn with a maximum of 6800 recruits per m2.

Time for community to reach maturity

An Ampharete biotope is likely to reach maturity very rapidly because the key species are short lived and reach maturity within a few months. Parvicardium ovale has a life span of less than a year (Lastra et al., 1993). There was no information found on the life-history characteristics of Ampharete falcata, however a related species Ampharete acutifrons was found to be an annual species (Price & Warwick, 1980). At a sub-littoral site in Swansea Bay Warwick & George (1980) observed three cohorts of Ampharete acutifrons co-existing so reproduction probably takes place over a protracted period. Recruitment of a similar species Ampharete acutifrons varied between 46 and 8996 individuals per m2 over a five year period (Price & Warwick, 1980) suggesting irregular recruitment and therefore time for the community to reach maturity.

Additional information

-

Preferences & Distribution

Recorded distribution in Britain and IrelandRecorded from Loch Etive and the Irish Sea.

Habitat preferences

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

Additional Information

Species composition

Species found especially in this biotope

    Rare or scarce species associated with this biotope

    -

    Additional information

    There is little information available on the two key species, Ampharete falcata and Parvicardium ovale and individual species reviews have not been carried out.

    Sensitivity reviewHow is sensitivity assessed?

    Explanation

    The key structural species in the biotope is the polychaete Ampharete falcata which creates a turf of tubes protruding from soft sediment. The small cockle Parvicardium ovale and the brittlestars Amphiura filiformis and Amphiura chiajei are superabundant in the biotope. When present in high enough numbers the burrowing activities of Amphiura filiformis can modify the stability of the sediment.

    Species indicative of sensitivity

    Community ImportanceSpecies nameCommon Name

    Physical Pressures

     IntoleranceRecoverabilitySensitivitySpecies RichnessEvidence/Confidence
    High Moderate Moderate Major decline Moderate
    Most species 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 many mobile species in the biotope that may be able to escape, most, such as Amphiura sp. brittlestars and small spider crabs, are not very fast moving and so are also likely to be removed. See additional information for recovery.
    High High Moderate Major decline Moderate
    Smothering by 5 cm of sediment is likely to lead to the death of some of the organisms in the biotope. The populations of tube dwelling polychaete Ampharete falcata will probably be unable to feed or respire and will die. Some individuals may be able rise through the sediment but survival is probably dependent on the speed at which new tubes can be built. Some of the burrowing fauna, such as the Amphiura spp. brittlestars and Nephrops norvegicus and the small bivalve Parvicardium ovale, will not be affected by smothering beyond re-establishing burrow openings or moving up through the sediment. Therefore, the overall impact of the factor on the biotope is likely to be the loss of the key polychaete species and so intolerance is reported to be high.
    Low Very high Very Low No change Moderate
    Many species in the biotope are either infaunal or deposit feeders that are not expected to be intolerant of an increase in suspended sediment at the level of the benchmark. Some species may benefit from increased food supply if suspended sediment has a high organic content. There may be additional cleaning costs for suspension feeders but this will not affect survival of animals. Intolerance of the biotope is therefore reported to be low. Recovery is likely to be very rapid as affected animals clean away sediment particles.
    Low Moderate Moderate Decline Very low
    Many species in the biotope are either infaunal or deposit feeders that are not expected to be intolerant of a decrease in suspended sediment at the benchmark level for a month. Food availability for some suspension feeding species may decline but this will not affect survival of animals. Intolerance of the biotope is therefore reported to be low.
    Not relevant Not relevant Not relevant Not relevant Not relevant
    The biotope is an offshore community so changes in desiccation are not relevant.
    Not relevant Not relevant Not relevant Not relevant Not relevant
    The biotope is an offshore community so an increase in emergence is not relevant.
    Not sensitive*
    The biotope is an offshore community so a decrease in emergence is not relevant.
    High Moderate Moderate Major decline Moderate
    The biotope habitat is fine sediment that only develops in areas of weak tidal streams. A long term increase in water flow rate is likely to affect the nature of the substratum as fine particles are washed away and a coarser sediment type remains. The species in the biotope may disappear as the substratum becomes unsuitable for tube building and burrowing. Intolerance of the biotope is reported to be high because most species are not expected to be able to survive a long term increase in water flow rates. Recovery could take a long time and is set to moderate - see additional information below for rationale.
    Not sensitive*
    The biotope occurs in weak tidal streams. A decrease may reduce the supply of particles to the suspension feeders and tube builders in the biotope. However, effects are only expected to be sub-lethal so intolerance is reported to be low. Normal feeding and tube building will resume on return to normal conditions.
    Low Very high Very Low No change Low
    There is no information on the response of the biotope to an increase in temperature. The biotope is found in relatively deep sublittoral habitats where the temperature may fluctuate by a maximum of about 10°C over the period of a year because of seasonal changes. Species are widely distributed in the north east Atlantic. Therefore, the biotope is likely to be able to tolerate a long term increase in temperature. However, some species may be more intolerant of a short term increase of 5°C. Intolerance to an increase in temperature is expected to be low but confidence in this assessment is low.
    Low Very high Moderate No change Low
    There is no information on the response of the biotope to a decrease in temperature. The biotope is found in relatively deep sublittoral habitats where the temperature may fluctuate by a maximum of about 10°C over the period of a year because of seasonal changes. Species are widely distributed in the north east Atlantic. Therefore, the biotope is likely to be able to tolerate a long term decrease in temperature. However, some species may be more intolerant of a short term decrease of 5°C. Intolerance is expected to be low but confidence in this assessment is low.
    Low Very high Very Low No change Moderate
    An increase in turbidity, reducing light availability may reduce primary production by phytoplankton in the water column. However, productivity in the COS.AmpPar biotope is secondary (detritus) and is not likely to be significantly affected by changes in turbidity and so intolerance is assessed as low. On return to normal turbidity levels recovery will be high as food availability returns to normal.
    Low Very high Moderate No change Moderate
    A decrease in turbidity, increasing light availability may increase primary production by phytoplankton in the water column. However, productivity in the COS.AmpPar biotope is secondary (detritus) and is not likely to be significantly affected by changes in turbidity and so intolerance is assessed as low. Nephrops novegicus avoid bright light and exposure to high intensities causes blindness (Loew, 1976) and so a decrease in light attenuation resulting from decreased turbidity may affect the depth at which the species is present or more likely that Nephrops will only feed at night
    High Moderate Moderate Major decline Low
    The biotope develops in sheltered areas and the depths at which the biotope is found will be rarely affected by wave disturbance. Thus, the biotope is likely to be highly intolerant of wave disturbance. The substratum is cohesive muddy sand or sandy mud which is likely to be mobilised by wave action removing both animals and the finer element of the substratum. Many of the species have a preference for fine sediments and may not be able to inhabit coarser material. Ampharete tubes form turfs on the surface of the sediment which are likely to be washed away if exposure were to increase by two exposure scales for a year. The small bivalve Parvicardium ovale could also be thrown into suspension by wave action. Loss of either one of the key species will result in the loss of the biotope so intolerance is assessed as high. See additional information for recovery.
    Not sensitive*
    The depths at which the biotope are found means that the community is rarely affected by wave disturbance. The substratum is cohesive muddy sand or sandy mud, further evidence that wave exposure is not a factor in this biotope and so a decrease in wave exposure is not relevant.
    Tolerant Not relevant Not relevant No change Moderate
    Ampharete falcata, Parvicardium ovale and some of the other species in the biotope may respond to vibrations from predators or excavation by retracting their palps into their tubes. However, most species in the biotope are unlikely to sensitive to noise and so the biotope is assessed as not sensitive.
    Tolerant Not relevant Not relevant No change Moderate
    The biotope occurs in deep water where available light is very low. Most species are likely to have no or poor visual perception or are burrowing and so 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 in the biotope will be affected by visual disturbance at the benchmark level and so a rank of not sensitive is reported.
    Intermediate High Low Decline Low
    Fauna that inhabit or construct tubes, such as Ampharete falcata are likely to be particularly vulnerable to damage or disturbance by beam trawls (Kaiser & Spencer, 1996). The biotope is also likely to be sensitive to physical disturbance by a passing scallop dredge However, it is not expected to remove the whole population of Ampharete spp. in the biotope and so intolerance is reported to be intermediate. 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. See additional information for recovery.
    Intermediate High Low Minor decline Very low
    Most species in the biotope are free-living and will be unaffected by displacement to a suitable substratum. However, although Ampharete spp. are probably able to rebuild a tube, the time to do so would probably leave individuals susceptible to predation and so most would not survive. With the loss of the polychaetes the biotope will no longer exist so intolerance is reported to be high. See additional information for recovery.

    Chemical Pressures

     IntoleranceRecoverabilitySensitivityRichnessEvidence/Confidence
    No information No information No information Not relevant Not relevant
    Insufficient
    information.
    Heavy metal contamination
    No information No information No information Not relevant Not relevant
    There is no information on the intolerance of the key species in the biotope. Experimental studies with various species suggests that polychaete worms are quite tolerant of heavy metals (Bryan, 1984). However, there is insufficient information to assess the intolerance of the biotope.
    Hydrocarbon contamination
    No information No information No information Not relevant Not relevant
    Insufficient
    information.
    Radionuclide contamination
    No information No information No information Not relevant Not relevant
    Insufficient
    information.
    Changes in nutrient levels
    Low Very high Very Low No change Low
    The biotope is found in areas of fine sediment where organic content will generally be higher than coarse sediments. Parvicardium exiguum and Ampharete grubei are both found in areas rich in silt and organic content (Lastra et al., 1993; Holme, 1949) and so the key species are likely to be similar. An increase in nutrients in subtidal habitats of this depth will not cause the biotope to become overgrown with ephemeral algae so the smothering effects often associated with eutrophication will not occur. Intolerance of the biotope to a 50% increase in nutrients is expected to be low and recovery will be rapid on return to normal conditions.
    High Moderate Moderate Decline Very low
    COS.AmpPar is a subtidal biotope, has not been recorded from hypersaline waters and so is probably intolerant of an increase in salinity and so a rank of high has been reported. See additional information for recovery.
    High Moderate Intermediate Decline Very low
    COS.AmpPar is a subtidal biotope, has not been recorded from estuaries for brackish waters and so is probably intolerant of a decrease in salinity and so a rank of high has been reported. See additional information for recovery.
    Intermediate Very high Low No change Very low
    There is no information regarding the effect of deoxygenation on the key species in the biotope or the biotope as a whole. Cole et al. (1999) suggest possible adverse effects on marine species below 4 mg/l and probable adverse effects below 2mg/l. Different 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 1 mg/l for several weeks and Amphiura chiajei is more tolerant of hypoxia (Nilsson, 1999).

    Biological Pressures

     IntoleranceRecoverabilitySensitivityRichnessEvidence/Confidence
    No information No information No information Insufficient
    information
    Not relevant
    There were no records found of any diseases or parasites affecting the species or the biotope. However, there is always the potential for this to occur in the future.
    Not relevant Not relevant Not relevant No change Moderate
    Although several non-native species of polychaete and mollusc have invaded British waters there are none that are likely to affect the COS.AmpPar biotope. However, there is always the potential for this to occur.
    Not relevant Not relevant Not relevant Not relevant Not relevant
    It is extremely unlikely that any of the species indicative of sensitivity would be targeted for extraction. Even in areas where Nephrops norvegicus is present, trawlers tend to avoid this type of community because the high densities of Ampharete tubes clog the nets.
    Low High Low No change Low

    Additional information

    Recoverability
    If the total population of the polychaete Ampharete falcata has been removed, recovery of the biotope will probably be very poor. Populations are often separated by great distances and recruitment from other populations is unlikely because the dispersal potential of larvae is restricted because the larvae are benthic. Thus, if total populations are lost recovery has been recorded as moderate. It is possible that other ampharetid polychaetes such as Melinna critata may replace Ampharete spp. so a functionally similar biotope could develop in a much shorter period. If some adults remain in the biotope after a perturbation, recovery will be more likely and would be recorded as high because local recruitment from benthic larvae can take place to return populations to previous abundance. The other key species in the biotope, Parvicardium ovale, is very widespread and reproduces every year so populations would be more likely to recover from loss. Other species such as the brittlestars are also very widespread and populations should recover within five years.

    Importance review

    Policy/Legislation

    Habitats of Principal ImportanceMud habitats in deep water
    Habitats of Conservation ImportanceMud habitats in deep water
    UK Biodiversity Action Plan PriorityMud habitats in deep water
    Priority Marine Features (Scotland)Offshore deep sea muds

    Exploitation

    The biotope is not likely to be exploited because although the commercially important Nephrops norvegicus may be present trawlers tend to avoid this type of community because the high densities of Ampharete tubes clog the nets.

    Additional information

    -

    Bibliography

    1. Bryan, G.W., 1984. Pollution due to heavy metals and their compounds. In Marine Ecology: A Comprehensive, Integrated Treatise on Life in the Oceans and Coastal Waters, vol. 5. Ocean Management, part 3, (ed. O. Kinne), pp.1289-1431. New York: John Wiley & Sons.
    2. Buchanan, J.B., 1964. A comparative study of some of the features of the biology of Amphiura filiformis and Amphiura chiajei (Ophiuroidea) considered in relation to their distribution. Journal of the Marine Biological Association of the United Kingdom, 44, 565-576.
    3. 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.
    4. Glémarec, M., 1979. Problemes d'ecologie dynamique et de succession en baie de Concarneau. Vie et Milieu, 28-29, 1-20.
    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. Holme, N.A., 1949. The fauna of sand and mud banks near the mouth of the Exe Estuary. Journal of the Marine Biological Association of the United Kingdom, 28, 189-237.
    7. Kaiser, M.J. & Spencer, B.E., 1996. The effects of beam-trawl disturbance on infaunal communities in different habitats. Journal of Animal Ecology, 65, 348-358.
    8. Lastra, M., Sanchez, A. & Mora, J., 1993. Population dynamics and secondary production of Parvicardium exiguum (Gmelin, 1790) in Santander Bay (N of Spain). Journal of Molluscan Studies, 59, 73-81.
    9. Loew, E.R., 1976. Light and photoreceptor degeneration in the Norway lobster Nephrops norvegicus (L.). Proceedings of the Royal Society of London, Series B, 193, 31-44.
    10. Muus, K., 1981. Density and growth of juvenile Amphiura filiformis (Ophiuroidea) in the Oresund. Ophelia, 20, 153-168.
    11. Nilsson, H.C., 1999. Effects of hypoxia and organic enrichment on growth of the brittle star Amphiura filiformis (O.F. Müller) and Amphiura chaijei Forbes. Journal of Experimental Marine Biology and Ecology, 237, 11-30.
    12. O'Connor, B. & McGrath, D., 1980. The population dynamics of Amphiura filiformis (O.F. Müller) in Galway Bay, west coast of Ireland. In Echinoderms: present and past (ed. M. Jangoux) p219-222. Rotterdam: A.A. Balkema.
    13. Price, R. & Warwick, R.M., 1980. Temporal variations in annual production and biomass in estuarine populations of two polychaetes, Nephtys hombergi and Ampharete acutifrons. Journal of the Marine Biological Association of the United Kingdom, 60, 481-487.
    14. Ramsay, K., Kaiser, M.J. & Hughes, R.N. 1998. The responses of benthic scavengers to fishing disturbance by towed gears in different habitats. Journal of Experimental Marine Biology and Ecology, 224, 73-89.
    15. Rasmussen, E., 1973. Systematics and ecology of the Isefjord marine fauna (Denmark). Ophelia, 11, 1-507.
    16. Rosenberg, R., 1995. Benthic marine fauna structured by hydrodynamic processes and food availability. Netherlands Journal of Sea Research, 34, 303-317.
    17. Rosenberg, R., Hellman, B. & Johansson, B., 1991. Hypoxic tolerance of marine benthic fauna. Marine Ecology Progress Series, 79, 127-131.
    18. Rowden, A.A., Jones, M.B. & Morris, A.W., 1998. The role of Callianassa subterranea (Montagu) (Thalassinidea) in sediment resuspension in the North Sea. Continental Shelf Research, 18, 1365-1380.
    19. Warwick, R.M. & George, C.L., 1980. Annual macro-fauna production in an Abra community. In Industrialised embayments and their environmental problems: a case study of Swansea Bay (ed. M.B. Collins et al.), pp. 517-538. Oxford: Pergamon Press.

    Citation

    This review can be cited as:

    Hill, J.M. 2001. Ampharete falcata turf with Parvicardium ovale on cohesive muddy sediment near margins of deep stratified seas. 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/75

    Last Updated: 23/07/2001