BIOTIC Species Information for Cerastoderma edule
|Researched by||Lizzie Tyler||Data supplied by||University of Sheffield|
|Refereed by||This information is not refereed.|
|Scientific name||Cerastoderma edule||Common name||Common cockle|
|MCS Code||W1961||Recent Synonyms||Cardium edule|
|Additional Information||Active suspension feeders, living in the top few centimetres of sediment. They are easily dislodged by storms and cockle beds can be washed away during winter gales. Commercially fished in areas such as Morecambe Bay, the Wash, Thames Estuary, Dee Estuary, Outer Hebrides and South Wales.|
|Taxonomy References||Fish & Fish, 1996, Hayward & Ryland, 1995b, Tebble, 1976, Boyden & Russel, 1972,|
||Feeding method||Passive suspension feeder
Active suspension feeder
|Typical food types||Phytoplankton, zooplankton and organic particulate matter.||Habit||Free living|
|Bioturbator||Flexibility||None (< 10 degrees)|
|Height||Insufficient information||Growth Rate||Variable (see additional information)|
|Adult dispersal potential||100-1000m||Dependency||Independent|
|General Biology Additional Information||Factors affecting growth
Growth rates of Cerastoderma edule vary with age, year, season, geographical location, tidal height, temperature regime, food availability, population density and interspecific competition.
Growth in Cerastoderma edule shows a marked seasonal pattern (Seed & Brown, 1977; Hancock & Franklin, 1972). In the Burry Inlet, Wales, shell growth commenced in May, continued through June until late August after which growth was negligible. Winter growth rates vary, e.g. negligible winter growth occurred for less than a month in the Menai Straits, Wales but for 158 days (between May -October) in Sorbotn, Norway although growth was more vigorous in young (first winter) than older specimens (Richardson et al. 1980). Adults may loose weight over winter (Hancock & Franklin, 1972; Newell & Bayne, 1980) probably due to lack of food. Mortality over winter was reported by several authors, e.g. Hancock & Urquhart (1964) report normal winter mortalities of 30 -90% in Burry Inlet, depending on size. After spawning the high food availability and reduced metabolic costs (compared with prior gametogenesis) allows Cerastoderma edule to synthesize carbohydrate reserves. The decline in body weight over winter and early spring is associated with the utilisation of lipid, protein and carbohydrate reserves (Newell & Bayne, 1980).
Reduced or negligible winter growth, together with disturbance results in clearly distinguishable external banding. Internal bands are laid down at semi-diurnal intervals related to the tidal cycle. Winter growth and internal bands have been used to age cockles, examine the past history of populations, population dynamics and monitoring (Orton, 1926; Richardson et al. 1979; Richardson et al., 1980; Jones & Baxter, 1987a).
Boyden (1972) reported castration of 13% of the population of Cerastoderma edule in the River Couch estuary due to infection with larval digenetic trematodes. Jonsson & Andre (1992) suggested that mass mortality of Cerastoderma edule occurring on the west coast of Sweden in the summer of 1991 was due to infestation by the larvae of the digenean trematode Cercaria cerastodermae I. Cercaria cerastodermae I has been recorded on British shores but was considered rare. The brucephalid cercariae, Cercaria fulbrighti primarily occupies digestive gland, foot and gonads. The parasitic copepod Paranthessius rostatus was reported in the mantle cavity of cockles around the British Isles (Atkins, 1934) and the Dutch Wadden Sea (sometimes 10s of parasites per individual) (Kristensen, 1958). The rhabdocele Paravortex cardiiand Paravortex karlings have also been reported in Cerastoderma edule in the British Isles (Pike & Burt, 1981; Atkins, 1934).
|Biology References||Fish & Fish, 1996, Hayward et al., 1996, Hayward & Ryland, 1995b, Tebble, 1976, Dame, 1996, Boyden, 1972, Boyden & Russel, 1972, Hancock & Franklin, 1972, Jones & Baxter, 1987a, Richardson et al., 1980, Richardson et al., 1979, Orton, 1926, Newell & Bayne, 1980, Johnsone, 1899, Guevara & Niell, 1989, Montaudouin & Bachelet, 1996, Montaudouin, 1996, Hancock, 1967, Ducrotoy et al. , 1991, Jensen, 1993, Smaal et al., 1997, Sanchez-Salazar et al. 1987, Olafsson et al., 1994., André et al. , 1993, Guillou & Tartu, 1994, Möller & Rosenberg, 1983, Hancock & Urquhart, 1964, Beukema, 1990, Atkins, 1934, Pike & Burt, 1981, Jonsson & Andre, 1992, Ansell et al., 1981, Hayward & Ryland, 1990, Julie Bremner, unpub data,|
|Distribution and Habitat|
|Distribution in Britain & Ireland||Widely distributed in estuaries and sandy bays around the coasts of Britain and Ireland.|
|Global distribution||Found from the western Barents Sea and northern Norway to the Iberian Peninsula, and south along the coast of west Africa to Senegal.|
|Biogeographic range||Not researched||Depth range|
|Migratory||Non-migratory / Resident|
|Distribution Additional Information||Boyden & Russell (1972) compared the habitat preferences of Cerastoderma edule and Cerastoderma glaucum. They concluded that Cerastoderma edule was excluded from hypo- or hyper-saline waters by insufficient tidal flow rather than salinity itself, and that Cerastoderma edule was unable to colonize still water conditions. Brock (1979) found Cerastoderma edule in Danish fjords with little tidal range and suggested that food availability was more important. However, Cerastoderma edule and Cerastoderma glaucum may be found together (sympatric), where stable sediments and good food availability occur e.g. Zostera sp. covered silt banks (Boyden & Russell, 1972; Brock, 1979).
|Substratum preferences||Sandy mud
Coarse clean sand
Fine clean sand
|Physiographic preferences||Enclosed coast / Embayment
Strait / sound
Ria / Voe
|Biological zone||Upper Eulittoral
|Tidal stream strength/Water flow||Moderately Strong (1-3 kn)
Weak (<1 kn)
Very Weak (negligible)
|Salinity||Reduced (18-30 psu)
Full (30-40 psu)
Variable (18-40 psu)
|Habitat Preferences Additional Information|
|Distribution References||Seaward, 1982, Seaward, 1990, Fish & Fish, 1996, Hayward et al., 1996, Hayward & Ryland, 1995b, Tebble, 1976, Dame, 1996, Boyden, 1972, Boyden & Russel, 1972, Hancock & Franklin, 1972, Jones & Baxter, 1987a, Richardson et al., 1980, Montaudouin & Bachelet, 1996, Montaudouin, 1996, Hancock, 1967, Ducrotoy et al. , 1991, Jensen, 1993, Smaal et al., 1997, Sanchez-Salazar et al. 1987, Olafsson et al., 1994., André et al. , 1993, Masski & Guillou, 1999, Guillou & Tartu, 1994, Möller & Rosenberg, 1983, Brock, 1979, Ansell et al., 1981, Hayward & Ryland, 1990,|
|Reproductive Season||Spawn over summer||Reproductive Location||Water column|
|Reproductive frequency||Annual protracted||Regeneration potential||No|
|Life span||6-10 years||Age at reproductive maturity||1-2 years|
|Generation time||1-2 years||Fecundity|
|Egg/propagule size||75 µm diameter||Fertilization type||External|
|Reproduction Preferences Additional Information||Longevity and sexual maturity
Cerastoderma edule may live for up to 9 years or more in some habitats but 2 -4 years is normal. The sex ratio was reported to be 40% males to 60% females (Fretter & Graham, 1964). Adults first mature and spawn in their second summer, at about 18 months old and 15-20 mm in length, however, large cockles (>15 mm) may mature in their first year suggesting that size and maturity are linked (Orton, 1926; Hancock & Franklin, 1972; Seed & Brown, 1977).
Gametogenesis is initiated in winter (October to March) but increases rapidly in spring (February -April) (Newell & Bayne, 1980) and the majority of the population are ripe by mid-summer (Seed & Brown, 1977). Most adults spawn in a short peak period over summer with remaining adults spawning over a protracted period, resulting in a short (ca. 3 month) period of peak settlement followed by generally declining numbers of recruits (Hancock, 1967; Seed & Brown, 1977). Spawning generally occurs between March - August in the UK followed by peak spatfall between May and September, however the exact dates vary between sites in the UK and Europe (Seed & Brown, 1977; Newell & Bayne, 1980). Boyden (1971) suggested that warming of water in spring to 13 °C or above was required to induce spawning, however Ducrotoy et al. (1991) suggested that a sudden temperature rise (rather than an absolute level) was probably required to initiate spawning. An occasional late peak in settlement may occur e.g. on the Llanrhidian Sands, Hancock (1967) reported an additional settlement peak in August -September after the main peak in May -July.
Fertilization is external. Males may release about 15 million sperm/sec and females were reported to release about 1900 eggs/sec. Gamete viability is short and André & Lindegarth (1995) found that fertilization was reduced to 50% in 2 hours and that no fertilization was observed after 4 -8 hrs. André & Lindegarth (1995) noted that fertilization efficiency was dependant on sperm concentration so that at high water flow rates fertilisation was only likely between close individuals. However, this may be compensated for by high population densities and synchronous spawning of a large proportion of the population. Eggs (50-60µm) develop into a trochophore stage within the egg membrane and then into a typical bivalve veliger at ca. 80µm, the D -larvae (so called due to the D -shaped shell) after about 3 -4 days the foot develops and the veliger metamorphoses into a juvenile cockle (pediveliger) at ca. 270µm after about 3 -5 weeks (Lebour, 1938; Creek, 1960). The juveniles reach ca. 600-700µm after about 3 weeks, and by 3 months are ca. 0.75-1.5 mm long (Creek, 1960).
Settlement and subsequent recruitment has a significant impact on the dynamics of Cerastoderma edule populations, in many but not all circumstances (Olaffsson et al., 1994). Settlement and recruitment is sporadic and varies with geographic location, year, season, reproductive condition of the adults and climatic variation. Factors reported to affect recruitment follow.
|Reproduction References||Fretter & Graham, 1964, Seed & Brown, 1977, Hancock & Franklin, 1972, Jones & Baxter, 1987a, Richardson et al., 1980, Orton, 1926, Newell & Bayne, 1980, Montaudouin & Bachelet, 1996, Ducrotoy et al. , 1991, Jensen, 1993, Lebour, 1938, Creek, 1960, Sanchez-Salazar et al. 1987, Olafsson et al., 1994., André et al. , 1993, Guillou & Tartu, 1994, Möller & Rosenberg, 1983, Hummel & Bogaaards, 1989, Kingston, 1974, Rygg, 1970, Ansell et al., 1981, Eckert, 2003, Julie Bremner, unpub data,|