Neocrania anomala and Protanthea simplex on sheltered circalittoral rock

01-04-2005
Researched byAngus Jackson Refereed byMatt Dalkin
EUNIS CodeA4.314 EUNIS NameNeocrania anomala and Protanthea simplex on sheltered circalittoral rock

Summary

UK and Ireland classification

EUNIS 2008A4.314Neocrania anomala and Protanthea simplex on sheltered circalittoral rock
EUNIS 2006A4.314Neocrania anomala and Protanthea simplex on sheltered circalittoral rock
JNCC 2004CR.LCR.BrAs.NeoProNeocrania anomala and Protanthea simplex on sheltered circalittoral rock
1997 BiotopeCR.SCR.BrAs.NeoProNeocrania anomala and Protanthea simplex on very sheltered circalittoral rock

Description

Deep rock (often vertical walls) in the landward basins of fjordic sea lochs often have dense Protanthea simplex growing on rock and tubes of Chaetopterus sp. and amongst Sabella pavonina. The underlying rock surfaces are covered with Neocrania anomala and large solitary ascidians such as Corella parallelogramma, Polycarpa pomaria, Ascidia mentula and Ascidia virginea are often present amongst the worm tubes. ROV records in Loch Duich from 60-160 m show a gradual change from the above to a community dominated by white Sabella and large numbers of Protula tubularia. (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

Present in sea lochs along the west coast of Scotland although not the Western Isles. Also locally in the south and west of Ireland as the variable salinity sub-biotope SCR.NeoPro.CaTw.

Depth range

5-10 m, 10-20 m, 20-30 m, 30-50 m

Additional information

-

Listed By

Further information sources

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JNCC

Habitat review

Ecology

Ecological and functional relationships

In this circalittoral biotope and similar sub-biotopes there are few algal species and limited primary production. The fauna is dominated by encrusting / attached species such as anemones, hydroids, brachiopods and solitary ascidians. The fauna consists predominantly of passive and active suspension feeders. There are a few errant predators and scavengers such as Cancer pagurus, and Asterias rubens. Particularly dense assemblages with abundant solitary sea squirts may provide shelter for other small fauna. Additional shelter may be provided by large sponges, particularly in the sub-biotopes.

Seasonal and longer term change

Ciona intestinalis is typically an annual species, particularly in reduced salinity water although reproduction can occur throughout the year. There will be some temporal changes in the coverage and shelter provided by this species. Otherwise, it is unlikely that there will be any seasonal or other temporal changes in the biotope.

Habitat structure and complexity

The sheltered conditions of the landward basins of sea lochs can allow quite species-rich assemblages to develop. Several tube worm species, including Chaetopterus variopedatus can be used by Protanthea simplex as a substratum. Larger species, including sponges and solitary ascidians provide greater spatial complexity. Higher densities of the hard, permanently attached Neocrania anomala may exclude other species.

Productivity

Primary productivity in this biotope is low although coralline algae were recorded in more than half of the records of this biotope and the brown algae Pseudolithoderma extensum in approximately one quarter of all records (JNCC, 1999). However, quite high densities of encrusting or attached organisms, primarily brachiopods, sea loch anemones, solitary ascidians and tube worms can result in quite high secondary productivity through suspension feeding.

Recruitment processes

Recruitment is primarily through pelagic larvae. Intense local recruitment can occur with Ciona intestinalis where sticky mucus strings containing eggs and larvae are trapped round nearby adults or other objects. Dispersal ability of Neocrania anomala may be limited and only occur from local populations. Protanthea simplex with is long-lived pelagic larval stage has considerable dispersal potential.

Time for community to reach maturity

None of the main characterizing species are particularly long lived. Neocrania anomala survives for possibly up to 10 years. Ciona intestinalis lives typically only for a year and populations can reproduce throughout the year. Large sponges may have considerably greater longevity and slower growth. It may take over five years for the community to reach maturity.

Additional information

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Preferences & Distribution

Recorded distribution in Britain and IrelandPresent in sea lochs along the west coast of Scotland although not the Western Isles. Also locally in the south and west of Ireland as the variable salinity sub-biotope SCR.NeoPro.CaTw.

Habitat preferences

Depth Range 5-10 m, 10-20 m, 20-30 m, 30-50 m
Water clarity preferencesPoor clarity / Extreme turbidity, Very high clarity / Very low turbidity, See additional information
Limiting Nutrients Data deficient
Salinity Full (30-40 psu)
Physiographic Enclosed coast / Embayment
Biological Zone Circalittoral
Substratum Bedrock, Large to very large boulders, Small boulders
Tidal Very Weak (negligible), Weak < 1 knot (<0.5 m/sec.)
Wave Extremely sheltered, Sheltered, Very sheltered
Other preferences

Additional Information

The two sub-biotopes included within this assessment are characterized by variable, reduced or low salinity which may influence biotope structure. The two sub-biotopes have some similarities although SCR.NeoPro.Den is more species rich and may occur in more open lochs (so far it has only been recorded from Loch Etive). The temperature preferences of the individual species selected to represent the biotope are quite different to the temperatures in which the biotope occurs in Britain and Ireland. For instance, Ciona intestinalis has a world-wide distribution and optimal growth occurs at between 15-20 degrees C, considerably higher than water temperatures on the west coast of Scotland. Protanthea simplex extends further north into colder waters. No information is available regarding limiting nutrients.

Species composition

Species found especially in this biotope

    Rare or scarce species associated with this biotope

    -

    Additional information

    The biotope assessment also covers two sub-biotopes. Ciona intestinalis is not one of the characterizing species in SCR.NeoPro.CaTw. However, Ciona intestinalis is assumed to form a suitable surrogate, representing the sensitivity of the various other solitary ascidians in the sub-biotope.

    Sensitivity reviewHow is sensitivity assessed?

    Explanation

    There are no species in this biotope that can be classified as 'key', i.e. species that if lost would result in loss or degradation of the associated community. Three important characterizing species have been selected that are important for the classification of this biotope. The biotope name includes Neocrania anomala and Protanthea simplex so these have been included. The parent biotope complex is 'Brachiopod and solitary ascidian communities (sheltered rock)' Ciona intestinalis has been included as a representative solitary ascidian that is found with high frequency in the biotope. The very large solitary ascidian Ascidia mentula was also recorded in more than half the of the records of this biotope although less information was available on this species with which to assess sensitivity.

    Species indicative of sensitivity

    Community ImportanceSpecies nameCommon Name
    Important characterizingCiona intestinalisA sea squirt
    Important characterizingProtanthea simplexSealoch anemone

    Physical Pressures

     IntoleranceRecoverabilitySensitivitySpecies RichnessEvidence/Confidence
    High Moderate Moderate Major decline Low
    All three important characterizing species are highly intolerant of substratum loss. The slower growing and longer lived Neocrania anomala will probably be the limiting factor in the recovery of the biotope although both Neocrania anomala and Protanthea simplex have moderate recoverability.
    High Moderate Moderate Major decline Moderate
    Both Neocrania anomala and Protanthea simplex are highly intolerant of smothering. Ciona intestinalis, being also recorded from areas of modified substratum and high siltation is more tolerant but still intermediately intolerant. The slower growing and longer lived Neocrania anomala will probably be the limiting factor in the recovery of the biotope although both Neocrania anomala and Protanthea simplex have moderate recoverability.
    Low Very high Very Low Minor decline Moderate
    All three of the selected important characterizing species have low intolerance to siltation. Neocrania anomala and Protanthea simplex have very high recoverability from siltation.
    Not relevant Not relevant Not relevant Not relevant High
    The deeper water location (greater than 10 m) of this biotope means that desiccation is highly unlikely to be a relevant factor.
    Not relevant Not relevant Not relevant Not relevant High
    The deep water location (greater than 10 m) of this biotope means that exposure to an emergence regime is highly unlikely to be a relevant factor.
    High Moderate Moderate Major decline Low
    The biotope occurs in the landward basins of fjordic sea lochs where water flow rate is likely to be low. Increases in flow rate may cause high intolerance in Neocrania anomala and intermediate intolerance in Protanthea simplex. The slower growing and longer lived Neocrania anomala will probably be the limiting factor in the recovery of the biotope.
    High Moderate Moderate Major decline Low
    Protanthea simplex has high intolerance to long term chronic temperature increases. The biotope has a restricted distribution along the west coast of Scotland. Long term increases in temperature will cause a decrease in available suitable habitat. Ciona intestinalis may be intermediately intolerant of short term acute decreases in temperature and Neocrania anomala may be intermediately intolerant of short term acute increases in temperature. Intolerance in the lower salinity biotopes where Protanthea simplex is absent may be different. The moderate recoverability of Protanthea simplex from temperature change is likely to be the slowest part of biotope recovery.
    Tolerant Not relevant Not relevant No change Low
    None of the selected important characterizing species from this biotope are intolerant of changes in turbidity.
    Not relevant Not relevant Not relevant Not relevant Moderate
    The selected important characterizing species in this biotope may have high or intermediate intolerance to wave exposure. However, the circalittoral and highly sheltered location of the biotope means that changes in wave exposure are extremely unlikely so the factor has been assessed as not relevant.
    Tolerant Not relevant Not relevant No change High
    Neocrania anomala has low intolerance to noise vibrations but overall the biotope is unlikely to be sensitive to disturbance by noise.
    Tolerant Not relevant Not relevant No change High
    Neocrania anomala has a shadow reflex that causes the valves to clamp shut giving a low intolerance to visual presence but overall, the biotope is unlikely to be sensitive to visual presence.
    High Moderate Moderate Major decline High
    Erect epifaunal species are particularly vulnerable to physical disturbance. Hydroids and bryozoans are likely to be removed or damaged by bottom trawling or dredging (Holt et al., 1995). Veale et al. (2000) reported that the abundance, biomass and production of epifaunal assemblages decreased with increasing fishing effort. Hydroid and bryozoan matrices were reported to be greatly reduced in fished areas (Jennings & Kaiser, 1998 and references therein). Damage to emergent epifauna was the first sign of damage from scallop dredging on horse mussel beds (see Modiolus modiolus) (Service & Magorrian, 1997; Service, 1988; Magorrian & Service, 1998). For example, Protanthea simplex and Ciona intestinalis were both considered to be highly intolerant of physical disturbance and abrasion (see species reviews). The growth form and more durable nature of the valves of Neocrania anomala suggested an intermediate intolerance. Given the likely intolerance of epifaunal communities, an overall intolerance of high has been suggested.

    The recolonization of epifauna on vertical rock walls was investigated by Sebens (1985, 1986). He reported that rapid colonizers such as encrusting corallines, encrusting bryozoans, amphipods, and tubeworms recolonized within 1-4 months. Ascidians such as Dendrodoa carnea, Molgula manhattensis and Aplidium spp. achieved significant cover in less than a year, and, together with Halichondria panicea, reached pre-clearance levels of cover after 2 years. A few individuals of Alcyonium digitatum and Metridium senile colonized within 4 years (Sebens, 1986). Large sponges and sea anemones would probably take longer to reach pre-clearance levels. Therefore, a recoverability of moderate has been recorded.

    High Moderate Moderate Major decline High
    Neocrania anomala individuals are cemented to the substratum and cannot reform an attachment if displaced from the substratum. Ciona intestinalis has some limited ability to reform attachments following displacement. The slower growing and longer lived Neocrania anomala will probably be the limiting factor in the recovery of the biotope.

    Chemical Pressures

     IntoleranceRecoverabilitySensitivityRichnessEvidence/Confidence
    No information No information No information Insufficient
    information
    Not relevant
    Insufficient
    information
    Heavy metal contamination
    No information No information No information Insufficient
    information
    Not relevant
    Insufficient
    information
    Hydrocarbon contamination
    No information No information No information Insufficient
    information
    Not relevant
    Insufficient
    information
    Radionuclide contamination
    No information No information No information Insufficient
    information
    Not relevant
    Insufficient
    information
    Changes in nutrient levels
    Tolerant Not relevant Not relevant No change Moderate
    There is some evidence that increased levels of organic nutrients is of benefit to Ciona intestinalis populations (Naranjo et al., 1996). Dissolved organic matter can also form a nutrition component for other species such as sponges. It is unlikely that changes in nutrient levels will have much effect on the biotope.
    Intermediate High Low Decline Low
    The biotope SCR.NeoPro contains Protanthea simplex which has intermediate intolerance to decreases in salinity. The sea loch anemone may only survive in fully saline waters as it is not found in the two similar sub-biotopes where salinity is variable, reduced or low. Reductions in salinity in the biotope may cause this species to be lost, changing the biotope. The two sub-biotopes A4.3142 and SCR.NeoPro.CaTw are characterized by low/reduced and variable salinity respectively. In SCR.NeoPro.Den, increases in salinity may cause high intolerance. Recoverability of SCR.NeoPro based on the recoverability of Protanthea simplex from change in salinity is high. However, in the sub-biotopes, where Protanthea simplex is absent recoverability may be different.
    Intermediate High Low Decline Low
    Protanthea simplex has intermediate intolerance to decreases in oxygen concentration. In the sub-biotopes where the sea loch anemone does not occur changes in oxygenation may have different effects. Brachiopods can sustain anaerobic metabolism for 3-5 days although at low oxygen concentrations, activity may be reduced. It is likely that characterizing species other than the three selected for the assessment are intolerant of decreases in oxygenation. Cole et al. (1999) suggest possible adverse effects on marine species below 4 mg/l and probable adverse effects below 2mg/l. Recoverability of SCR.NeoPro based on the recoverability of Protanthea simplex and Neocrania anomala from change in oxygenation is likely to be high. However, in the sub-biotopes, where Protanthea simplex is absent, recoverability may be different.

    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
    Not relevant Not relevant Not relevant Not relevant Low
    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.
    Not relevant Not relevant Not relevant Not relevant Low

    Additional information

    -

    Importance review

    Policy/Legislation

    Habitats Directive Annex 1Reefs

    Exploitation

    There is no known exploitation of this biotope or the selected characterizing species.

    Additional information

    The biotope SCR.NeoPro is recorded as uncommon and the two sub-biotopes are recorded as scarce.

    Bibliography

    1. Carlgren, O., 1921. Actiniaria, part 1.
    2. Carlgren, O., 1949. A survey of the Ptychodactiaria, Corallimorpharia and Actiniaria. Kungliga Svenska Vetenskapsakadamiens Handlingar, Series 4, 1, 16-110.
    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. Davies, C.E. & Moss, D., 1998. European Union Nature Information System (EUNIS) Habitat Classification. Report to European Topic Centre on Nature Conservation from the Institute of Terrestrial Ecology, Monks Wood, Cambridgeshire. [Final draft with further revisions to marine habitats.], Brussels: European Environment Agency.
    5. Holt, T.J., Jones, D.R., Hawkins, S.J. & Hartnoll, R.G., 1995. The sensitivity of marine communities to man induced change - a scoping report. Countryside Council for Wales, Bangor, Contract Science Report, no. 65.
    6. James, M.A., Ansell, A.D., Collins, M.J., Curry, G.B., Peck, L.S. & Rhoda, M.C., 1992. Biology of living brachiopods. Advances in Marine Biology, 28, 175-387.
    7. Jennings, S. & Kaiser, M.J., 1998. The effects of fishing on marine ecosystems. Advances in Marine Biology, 34, 201-352.
    8. JNCC (Joint Nature Conservation Committee), 1999. Marine Environment Resource Mapping And Information Database (MERMAID): Marine Nature Conservation Review Survey Database. [on-line] http://www.jncc.gov.uk/mermaid,
    9. Long, J.A. & Stricker, S.A., 1991. Brachiopoda. In Reproduction of marine invertebrates, Vol. VI. Echinoderms and Lophophorates. (ed. A.C. Giese, J.S. Pearse & V.B. Pearse). California: The Boxwood Press.
    10. Magorrian, B.H. & Service, M., 1998. Analysis of underwater visual data to identify the impact of physical disturbance on horse mussel (Modiolus modiolus) beds. Marine Pollution Bulletin, 36, 354-359.
    11. Marin, M.G., Bresan, M., Beghi, L. & Brunetti, R., 1987. Thermo-haline tolerance of Ciona intestinalis (L. 1767) at different developmental stages. Cahiers de Biologie Marine, 28, 45-57.
    12. MBA (Marine Biological Association), 1957. Plymouth Marine Fauna. Plymouth: Marine Biological Association of the United Kingdom.
    13. Nyholm, K-G., 1959. On the development of the primitive actinian Protanthea simplex, Carlgren. Zoologiska Bidrag Fran Uppsala, Band 33 1958-1962, 69-78.
    14. Sebens, K.P., 1985. Community ecology of vertical rock walls in the Gulf of Maine: small-scale processes and alternative community states. In The Ecology of Rocky Coasts: essays presented to J.R. Lewis, D.Sc. (ed. P.G. Moore & R. Seed), pp. 346-371. London: Hodder & Stoughton Ltd.

    15. Sebens, K.P., 1986. Spatial relationships among encrusting marine organisms in the New England subtidal zone. Ecological Monographs, 56, 73-96.

    16. Service, M. & Magorrian, B.H., 1997. The extent and temporal variation of disturbance to epibenthic communities in Strangford Lough, Northern Ireland. Journal of the Marine Biological Association of the United Kingdom, 77, 1151-1164.
    17. Service, M., 1998. Recovery of benthic communities in Strangford Lough following changes in fishing practice. ICES Council Meeting Paper, CM 1998/V.6, 13pp., Copenhagen: International Council for the Exploration of the Sea (ICES).
    18. Svane, I. & Havenhand, J.N., 1993. Spawning and dispersal in Ciona intestinalis (L.) Marine Ecology, Pubblicazioni della Stazione Zoologica di Napoli. I, 14 , 53-66.

    19. Veale, L.O., Hill, A.S., Hawkins, S.J. & Brand, A.R., 2000. Effects of long term physical disturbance by scallop fishing on subtidal epifaunal assemblages and habitats. Marine Biology, 137, 325-337.

    Citation

    This review can be cited as:

    Jackson, A. 2005. Neocrania anomala and Protanthea simplex on sheltered circalittoral rock. 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/5

    Last Updated: 01/04/2005