Lagoon cockle (Cerastoderma glaucum)

Three Cerastoderma glaucum with siphons extended.

Photographer: Dennis R. Seaward Copyright: Dennis R. Seaward

Distribution data supplied by the Ocean Biodiversity Information System (OBIS). To interrogate UK data visit the NBN Atlas.Map Help

Researched by	Nicola White	Refereed by	Dr Richard S.K. Barnes
Researched by Nicola White	Refereed by Dr Richard S.K. Barnes
Authority	(Bruguière, 1789)
Authority (Bruguière, 1789)
Other common names	-	Synonyms	Cardium lamarckii (Bruguière, 1789)
Other common names -	Synonyms Cardium lamarckii (Bruguière, 1789)

Summary

Description

The cockle, Cerastoderma glaucum is a filter feeding bivalve which burrows shallowly in soft sediments. The species exists in two forms, a typical thin-shelled variety found in brackish lagoon habitats and a thicker shelled variety occurring in estuaries. It is widely distributed in north-west Europe.

Recorded distribution in Britain and Ireland

Orkney, Firth of Forth, East Anglia, Deben & Orwell estuaries, south coast of England, south Wales, the west coast of Scotland, and south and west coasts of Ireland.

Global distribution

Occurs from Norway and the Baltic to the Mediterranean and Black Seas.

Habitat

The species is found submerged in saline lagoons or more rarely on the low shore of estuaries. Adults usually burrow shallowly in soft sediments. The failure of the species to colonize the higher shore is believed to be due to an inability to tolerate aerial exposure and it's consequent conditions. The species' distribution is believed to be restricted by the damaging effect of wave action on the newly settled spat.

Depth range

Shallow

Identifying features

Rounded globular shell with 22-28 conspicuous radiating ribs.
Anterior margin of shell crenulate, posterior margin smooth.
Hinge line with cardinal and lateral teeth.
Adductor muscle scars roughly the same size.
Pallial sinus absent.

Additional information

No text entered

Listed by

Biology review

Taxonomy

Level	Scientific name	Common name
Phylum	Mollusca	Snails, slugs, mussels, cockles, clams & squid
Snails, slugs, mussels, cockles, clams & squid
Class	Bivalvia	Clams, cockles, mussels, oysters, and scallops
Clams, cockles, mussels, oysters, and scallops
Order	Cardiida

Family	Cardiidae
Genus	Cerastoderma
Authority	(Bruguière, 1789)
Recent Synonyms	Cardium lamarckii (Bruguière, 1789)

Biology

Parameter	Data
Typical abundance	Low density
Male size range	Up to 5cm
Male size at maturity
Female size range	Small-medium(3-10cm)
Female size at maturity
Growth form	Bivalved
Growth rate	9.6mm/year
Body flexibility
Mobility
Characteristic feeding method	Active suspension feeder, No information
Diet/food source	Planktotroph
Typically feeds on
Sociability
Environmental position	Infaunal
Dependency	No information found.
Supports	No information
Is the species harmful?	No

Biology information

The species exists in two forms, a typical thin-shelled variety found in brackish lagoon habitats and a thicker shelled variety occurring in estuaries. Growth rate during the first year takes place at a mean of 9.6 mm per year in Essex. Thereafter growth rate decreases to 4.9 mm in the second year and 2.5 mm in the third year (Boyden, 1972).

Habitat preferences

Parameter	Data
Physiographic preferences	Estuary, Isolated saline water (Lagoon)
Biological zone preferences	Lower eulittoral, Sublittoral fringe
Substratum / habitat preferences	Coarse clean sand, Fine clean sand, Mud, Muddy sand, Sandy mud
Tidal strength preferences	Weak < 1 knot (<0.5 m/sec.)
Wave exposure preferences	Sheltered, Very sheltered
Salinity preferences	Low (<18 psu), Variable (18-40 psu)
Depth range	Shallow
Other preferences	No text entered
Migration Pattern	Non-migratory or resident

Habitat Information

The adult and juvenile populations are distributed differently. Juveniles (0.5-10 mm) attach to filamentous algae by means of byssus threads. When they reach a certain age, they migrate to the adult free-living sediment population (Labourg & Lasserre, 1980).

Life history

Adult characteristics

Parameter	Data
Reproductive type	Gonochoristic (dioecious)
Reproductive frequency	Annual episodic
Fecundity (number of eggs)	No information
Generation time	Insufficient information
Age at maturity	Insufficient information
Season	May - July
Life span	2-5 years

Larval characteristics

Parameter	Data
Larval/propagule type	-
Larval/juvenile development	Planktotrophic
Duration of larval stage	11-30 days
Larval dispersal potential	No information
Larval settlement period	Insufficient information

Life history information

Veliger larvae have a pelagic life of from 11 to 30 days. Newly settled young attach temporarily by byssus threads to filamentous algae before becoming buried in the top few centimetres of sediment. Gametogenesis occurs in early spring and spawning takes place from May to July. Individuals live for about five years.

Sensitivity reviewHow is sensitivity assessed?

The MarLIN sensitivity assessment approach used below has been superseded by the MarESA (Marine Evidence-based Sensitivity Assessment) approach (see menu). The MarLIN approach was used for assessments from 1999-2010. The MarESA approach reflects the recent conservation imperatives and terminology and is used for sensitivity assessments from 2014 onwards.

Physical pressures

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	Intolerance	Recoverability	Sensitivity	Evidence / Confidence
Substratum loss [Show more] Substratum loss Benchmark. All of the substratum occupied by the species or biotope under consideration is removed. A single event is assumed for sensitivity assessment. Once the activity or event has stopped (or between regular events) suitable substratum remains or is deposited. Species or community recovery assumes that the substratum within the habitat preferences of the original species or community is present. Further details Evidence Cerastoderma glaucum lives embedded within the substratum and would be removed upon substratum loss. The species has slow recovery due to its restricted distribution.	High	Low	High	Low
Smothering [Show more] Smothering Benchmark. All of the population of a species or an area of a biotope is smothered by sediment to a depth of 5 cm above the substratum for one month. Impermeable materials, such as concrete, oil, or tar, are likely to have a greater effect. Further details. Evidence Bivalves have rather limited ability to burrow upwards so the species would be buried upon smothering. Cerastoderma glaucum has slow recovery due to it's restricted distribution.	High	Low	High	Low
Increase in suspended sediment [Show more] Increase in suspended sediment Benchmark. An arbitrary short-term, acute change in background suspended sediment concentration e.g., a change of 100 mg/l for one month. The resultant light attenuation effects are addressed under turbidity, and the effects of rapid settling out of suspended sediment are addressed under smothering. Further details Evidence The species is probably tolerant of siltation because it lives in estuaries and lagoons where siltation frequently occurs.	Tolerant	Not relevant	Not sensitive	Low
Decrease in suspended sediment [Show more] Decrease in suspended sediment Benchmark. An arbitrary short-term, acute change in background suspended sediment concentration e.g., a change of 100 mg/l for one month. The resultant light attenuation effects are addressed under turbidity, and the effects of rapid settling out of suspended sediment are addressed under smothering. Further details Evidence			No information
Desiccation [Show more] Desiccation A normally subtidal, demersal or pelagic species including intertidal migratory or under-boulder species is continuously exposed to air and sunshine for one hour. A normally intertidal species or community is exposed to a change in desiccation equivalent to a change in position of one vertical biological zone on the shore, e.g., from upper eulittoral to the mid eulittoral or from sublittoral fringe to lower eulittoral for a period of one year. Further details. Evidence The low shore position of Cerastoderma glaucum suggests that it has a low tolerance of desiccation. Boyden (1972) observed that the species can tolerate 33 percent water loss and that death occurs between 33 and 38 percent water loss. Recovery would be low due to the restricted distribution of this species.	High	Low	High	Moderate
Increase in emergence regime [Show more] Increase in emergence regime Benchmark. A one hour change in the time covered or not covered by the sea for a period of one year. Further details Evidence The low shore position of Cerastoderma glaucum suggests that its has an inability to tolerate exposure to air and it's consequent conditions. Unlike Cerastoderma edule the shells of Cerastoderma glaucum remain closed upon exposure to air. The species may suffer desiccation, increased metabolic cost and exposure to predation by birds. Recovery would be low due to the restricted distribution of this species.	High	Low	High	Low
Decrease in emergence regime [Show more] Decrease in emergence regime Benchmark. A one hour change in the time covered or not covered by the sea for a period of one year. Further details Evidence			No information
Increase in water flow rate [Show more] Increase in water flow rate A change of two categories in water flow rate (view glossary) for 1 year, for example, from moderately strong (1-3 knots) to very weak (negligible). Further details Evidence The species and its preferred habitat could be washed away by increased water flow rate. Recovery would be slow due to the restricted distribution of the species.	Intermediate	Low	High	Very low
Decrease in water flow rate [Show more] Decrease in water flow rate A change of two categories in water flow rate (view glossary) for 1 year, for example, from moderately strong (1-3 knots) to very weak (negligible). Further details Evidence			No information
Increase in temperature [Show more] Increase in temperature A short-term, acute change in temperature; e.g., a 5°C change in the temperature range for three consecutive days. This definition includes ‘short-term’ thermal discharges. A long-term, chronic change in temperature; e.g. a 2°C change in the temperature range for a year. This definition includes ‘long term’ thermal discharges. For intertidal species or communities, the range of temperatures includes the air temperature regime for that species or community. Further details Evidence Cerastoderma glaucum can tolerate a wide range of temperatures. Populations have been observed to survive in lagoons in conditions from almost freezing to more than 30 degree C. However, a high mortality of cockles was observed in South East England after the exceptionally cold winter of 1962/3. Boyden (1972) observed that Cerastoderma glaucum has a LD50 of 62.3 hours at 20 degrees C in air.	Low	High	Low	Moderate
Decrease in temperature [Show more] Decrease in temperature A short-term, acute change in temperature; e.g., a 5°C change in the temperature range for three consecutive days. This definition includes ‘short-term’ thermal discharges. A long-term, chronic change in temperature; e.g. a 2°C change in the temperature range for a year. This definition includes ‘long term’ thermal discharges. For intertidal species or communities, the range of temperatures includes the air temperature regime for that species or community. Further details Evidence			No information
Increase in turbidity [Show more] Increase in turbidity A short-term, acute change; e.g., two categories of the water clarity scale (see glossary) for one month, such as from medium to extreme turbidity. A long-term, chronic change; e.g., one category of the water clarity scale (see glossary) for one year, such as from low to medium turbidity. Further details Evidence The species is a suspension feeder so may benefit from increased turbidity by a greater food supply. However, if turbidity is caused by silt particles additional feeding costs would be imposed.	Low	High	Low	Low
Decrease in turbidity [Show more] Decrease in turbidity A short-term, acute change; e.g., two categories of the water clarity scale (see glossary) for one month, such as from medium to extreme turbidity. A long-term, chronic change; e.g., one category of the water clarity scale (see glossary) for one year, such as from low to medium turbidity. Further details Evidence			No information
Increase in wave exposure [Show more] Increase in wave exposure A change of two ranks on the wave exposure scale (view glossary) e.g., from Exposed to Extremely exposed for a period of one year. Further details Evidence It has been suggested that the juveniles of Cerastoderma glaucum are very intolerant of wave exposure which controls the species' distribution. The species is restricted to sheltered sites which suggests it is intolerant of increased wave exposure. Increased wave exposure may also remove the species preferred habitat. Recovery would be low due to the species' limited distribution.	High	Low	High	Low
Decrease in wave exposure [Show more] Decrease in wave exposure A change of two ranks on the wave exposure scale (view glossary) e.g., from Exposed to Extremely exposed for a period of one year. Further details Evidence			No information
Noise [Show more] Noise Underwater noise levels e.g., the regular passing of a 30-metre trawler at 100 metres or a working cutter-suction transfer dredge at 100 metres for one month during important feeding or breeding periods. Atmospheric noise levels e.g., the regular passing of a Boeing 737 passenger jet 300 metres overhead for one month during important feeding or breeding periods. Further details Evidence Insufficient information	No information	Not relevant	No information	Not relevant
Visual presence [Show more] Visual presence Benchmark. The continuous presence for one month of moving objects not naturally found in the marine environment (e.g., boats, machinery, and humans) within the visual envelope of the species or community under consideration. Further details Evidence Insufficient information	No information	Not relevant	No information	Not relevant
Abrasion & physical disturbance [Show more] Abrasion & physical disturbance Benchmark. Force equivalent to a standard scallop dredge landing on or being dragged across the organism. A single event is assumed for assessment. This factor includes mechanical interference, crushing, physical blows against, or rubbing and erosion of the organism or habitat of interest. Where trampling is relevant, the evidence and trampling intensity will be reported in the rationale. Further details. Evidence The shells of Cerastoderma glaucum are rather thin and brittle, so it is probably quite intolerant of abrasion.	Intermediate	Moderate	Moderate	Very low
Displacement [Show more] Displacement Benchmark. Removal of the organism from the substratum and displacement from its original position onto a suitable substratum. A single event is assumed for assessment. Further details Evidence The species is not sensitive to displacement. A population of Cerastoderma glaucum established itself in Emsworth Harbour by displacement of animals from adjacent lagoon habitats (Barnes, 1973).	Tolerant	Very high	Not sensitive	Moderate

Chemical pressures

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	Intolerance	Recoverability	Sensitivity	Evidence / Confidence
Synthetic compound contamination [Show more] Synthetic compound contamination Sensitivity is assessed against the available evidence for the effects of contaminants on the species (or closely related species at low confidence) or community of interest. For example: evidence of mass mortality of a population of the species or community of interest (either short or long term) in response to a contaminant will be ranked as high sensitivity; evidence of reduced abundance, or extent of a population of the species or community of interest (either short or long term) in response to a contaminant will be ranked as intermediate sensitivity; evidence of sub-lethal effects or reduced reproductive potential of a population of the species or community of interest will be assessed as low sensitivity. The evidence used is stated in the rationale. Where the assessment can be based on a known activity then this is stated. The tolerance to contaminants of species of interest will be included in the rationale when available; together with relevant supporting material. Further details. Evidence Insufficient information	No information	No information	No information	Not relevant
Heavy metal contamination [Show more] Heavy metal contamination Evidence Insufficient information	No information	No information	No information	Not relevant
Hydrocarbon contamination [Show more] Hydrocarbon contamination Evidence Insufficient information	No information	No information	No information	Not relevant
Radionuclide contamination [Show more] Radionuclide contamination Evidence Insufficient information	No information	Not relevant	No information	Not relevant
Changes in nutrient levels [Show more] Changes in nutrient levels Evidence An increase in nutrients may lead to eutrophication and reduced oxygen levels. Juveniles of the species are very intolerant of reduced oxygen concentration. Recovery would be low due to the restricted distribution of this species.	Intermediate	Low	High	Low
Increase in salinity [Show more] Increase in salinity A short-term, acute change; e.g., a change of two categories from the MNCR salinity scale for one week (view glossary) such as from full to reduced. A long-term, chronic change; e.g., a change of one category from the MNCR salinity scale for one year (view glossary) such as from reduced to low. Further details. Evidence The species can survive in lagoons where salinity varies from 7 psu to 84 psu, so it has a high tolerance of different salinities.	Low	High	Low	Moderate
Decrease in salinity [Show more] Decrease in salinity A short-term, acute change; e.g., a change of two categories from the MNCR salinity scale for one week (view glossary) such as from full to reduced. A long-term, chronic change; e.g., a change of one category from the MNCR salinity scale for one year (view glossary) such as from reduced to low. Further details. Evidence			No information
Changes in oxygenation [Show more] Changes in oxygenation Benchmark. Exposure to a dissolved oxygen concentration of 2 mg/l for one week. Further details. Evidence Juveniles of Cerastoderma glaucum are very intolerant of low oxygen concentrations. However adults can survive for 84 hours in oxygen free water (Boyden, 1972).	High	Low	High	Moderate

Biological pressures

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	Intolerance	Recoverability	Sensitivity	Evidence / Confidence
Introduction of microbial pathogens/parasites [Show more] Introduction of microbial pathogens/parasites Benchmark. Sensitivity can only be assessed relative to a known, named disease, likely to cause partial loss of a species population or community. Further details. Evidence Insufficient information	No information	Not relevant	No information	Not relevant
Introduction of non-native species [Show more] Introduction of non-native species Sensitivity assessed against the likely effect of the introduction of alien or non-native species in Britain or Ireland. Further details. Evidence Insufficient information	No information	Not relevant	No information	Not relevant
Extraction of this species [Show more] Extraction of this species Benchmark. Extraction removes 50% of the species or community from the area under consideration. Sensitivity will be assessed as 'intermediate'. The habitat remains intact or recovers rapidly. Any effects of the extraction process on the habitat itself are addressed under other factors, e.g. displacement, abrasion and physical disturbance, and substratum loss. Further details. Evidence Insufficient information	No information	Not relevant	No information	Not relevant
Extraction of other species [Show more] Extraction of other species Benchmark. A species that is a required host or prey for the species under consideration (and assuming that no alternative host exists) or a keystone species in a biotope is removed. Any effects of the extraction process on the habitat itself are addressed under other factors, e.g. displacement, abrasion and physical disturbance, and substratum loss. Further details. Evidence Insufficient information	No information	Not relevant	No information	Not relevant

Additional information

None

Importance review

Policy/legislation

Designation	Support
Northern Ireland Priority Species	Yes

Status

National (GB) importance	Not rare or scarce	Global red list (IUCN) category	-
National (GB) importance Not rare or scarce
Global red list (IUCN) category -

Non-native

Parameter	Data
Native	-
Origin	-
Date Arrived	-

Importance information

The species is harvested in Yugoslavia for human consumption, and may be harvested elsewhere.

Bibliography

Anonymous, 1999s. Saline lagoons. Habitat Action Plan. In UK Biodiversity Group. Tranche 2 Action Plans. English Nature for the UK Biodiversity Group, Peterborough., English Nature for the UK Biodiversity Group, Peterborough.
Ansell, A.D., Barnett, P.R.O., Bodoy, A. & Masse, H., 1981. Upper temperature tolerances of some European Mollusca III. Cardium glaucum, C. tuberculata and C. edule. Marine Biology, 65, 177-183.
Barnes, R.S.K., 1973. The intertidal lamellibranchs of Southampton Water, with particular reference to Cerastoderma edule and C. glaucum. Proceedings of the Malacological Society of London, 40, 413-433.
Barnes, R.S.K., 1980b. Coastal lagoons. The natural history of a neglected habitat. Cambridge: Cambridge University Press.
Barnes, R.S.K., 1994. The brackish-water fauna of northwestern Europe. Cambridge: Cambridge University Press.
Boyden, C.R. & Russel, P.J.C., 1972. The distribution and habitat range of the brackish water cockle (Cardium (Cerastoderma) edule) in the British Isles. Journal of Animal Ecology, 41, 719-734.
Boyden, C.R., 1972. Behaviour, survival and respiration of the cockles Cerastoderma edule and C. glaucum in air. Journal of the Marine Biological Association of the United Kingdom, 52, 661-680.
Brock, V., 1979. Habitat selection of two congeneric bivalves, Cardium edule and C. glaucum in sympatric and allopatric populations. Marine Biology, 54, 149-156.
Howson, C.M. & Picton, B.E., 1997. The species directory of the marine fauna and flora of the British Isles and surrounding seas. Belfast: Ulster Museum. [Ulster Museum publication, no. 276.]
Labourg, P.J., Lasserre, G., 1980. Population Dynamics of Cerastoderma glaucum in an Artificial Lagoon of the Arcachon Region. Marine Biology, 60, 147-157.
Rygg, B., 1970. Studies on Cerastoderma edule (L.) and Cerastoderma glaucum (Poiret). Sarsia, 43, 65-80.
Seaward, D.R., 1982. Sea area atlas of the marine molluscs of Britain and Ireland. Peterborough: Nature Conservancy Council.
Seaward, D.R., 1990. Distribution of marine molluscs of north west Europe. Peterborough: Nature Conservancy Council.

Datasets

Bristol Regional Environmental Records Centre, 2017. BRERC species records recorded over 15 years ago. Occurrence dataset: https://doi.org/10.15468/h1ln5p accessed via GBIF.org on 2018-09-25.
Centre for Environmental Data and Recording, 2018. Ulster Museum Marine Surveys of Northern Ireland Coastal Waters. Occurrence dataset https://www.nmni.com/CEDaR/CEDaR-Centre-for-Environmental-Data-and-Recording.aspx accessed via NBNAtlas.org on 2018-09-25.
Cofnod – North Wales Environmental Information Service, 2018. Miscellaneous records held on the Cofnod database. Occurrence dataset: https://doi.org/10.15468/hcgqsi accessed via GBIF.org on 2018-09-25.
Conchological Society of Great Britain & Ireland, 2018. Mollusc (marine) data for Great Britain and Ireland - restricted access. Occurrence dataset: https://doi.org/10.15468/4bsawx accessed via GBIF.org on 2018-09-25.
Conchological Society of Great Britain & Ireland, 2023. Mollusc (marine) records for Great Britain and Ireland. Occurrence dataset: https://doi.org/10.15468/aurwcz accessed via GBIF.org on 2024-09-27.
Environmental Records Information Centre North East, 2018. ERIC NE Combined dataset to 2017. Occurrence dataset: http://www.ericnortheast.org.ukl accessed via NBNAtlas.org on 2018-09-38
Fenwick, 2018. Aphotomarine. Occurrence dataset http://www.aphotomarine.com/index.html Accessed via NBNAtlas.org on 2018-10-01
Kent Wildlife Trust, 2018. Kent Wildlife Trust Shoresearch Intertidal Survey 2004 onwards. Occurrence dataset: https://www.kentwildlifetrust.org.uk/ accessed via NBNAtlas.org on 2018-10-01.
Lancashire Environment Record Network, 2018. LERN Records. Occurrence dataset: https://doi.org/10.15468/esxc9a accessed via GBIF.org on 2018-10-01.
National Trust, 2017. National Trust Species Records. Occurrence dataset: https://doi.org/10.15468/opc6g1 accessed via GBIF.org on 2018-10-01.
NBN (National Biodiversity Network) Atlas. Available from: https://www.nbnatlas.org.
Norfolk Biodiversity Information Service, 2017. NBIS Records to December 2016. Occurrence dataset: https://doi.org/10.15468/jca5lo accessed via GBIF.org on 2018-10-01.
North East Scotland Biological Records Centre, 2017. NE Scotland mollusc records 1800-2010. Occurrence dataset: https://doi.org/10.15468/qsluwv accessed via GBIF.org on 2018-10-01.
OBIS (Ocean Biodiversity Information System), 2025. Global map of species distribution using gridded data. Available from: Ocean Biogeographic Information System. www.iobis.org. Accessed: 2025-04-30
Outer Hebrides Biological Recording, 2018. Invertebrates (except insects), Outer Hebrides. Occurrence dataset: https://doi.org/10.15468/hpavud accessed via GBIF.org on 2018-10-01.
South East Wales Biodiversity Records Centre, 2018. SEWBReC Molluscs (South East Wales). Occurrence dataset: https://doi.org/10.15468/jos5ga accessed via GBIF.org on 2018-10-02.
South East Wales Biodiversity Records Centre, 2018. Dr Mary Gillham Archive Project. Occurance dataset: http://www.sewbrec.org.uk/ accessed via NBNAtlas.org on 2018-10-02
Suffolk Biodiversity Information Service., 2017. Suffolk Biodiversity Information Service (SBIS) Dataset. Occurrence dataset: https://doi.org/10.15468/ab4vwo accessed via GBIF.org on 2018-10-02.

Citation

This review can be cited as:

White, N. 2002. Cerastoderma glaucum Lagoon cockle. In Tyler-Walters H. Marine Life Information Network: Biology and Sensitivity Key Information Reviews, [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 30-04-2025]. Available from: https://www.marlin.ac.uk/species/detail/1315

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Last Updated: 15/07/2002

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