BIOTIC

BIOTIC Species Information for Cerastoderma edule
All Taxonomy Biology Distribution Reproduction

Researched by	Lizzie Tyler	Data supplied by	University of Sheffield
Refereed by	This information is not refereed.
General Biology
Growth form	Bivalved	Feeding method	Passive suspension feeder Active suspension feeder
Mobility/Movement	Crawler Burrower	Environmental position	Infaunal
Typical food types	Phytoplankton, zooplankton and organic particulate matter.	Habit	Free living
Bioturbator		Flexibility	None (< 10 degrees)
Fragility	Robust	Size	Small-medium(3-10cm)
Height	Insufficient information	Growth Rate	Variable (see additional information)
Adult dispersal potential	100-1000m	Dependency	Independent
Sociability	Gregarious
Toxic/Poisonous?	No
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. Cerastoderma edule grow rapidly in their first 1 -2 years after which growth rate declines with increasing size (Seed & Brown, 1977). Growth rates decrease with increasing tidal height, probably due to decreased immersion times and hence reduced food availability at higher shore heights (Richardson et al., 1980; Jensen, 1993; Montaudouin & Bachelet, 1996; Montaudouin, 1996). The highest growth rates in Cerastoderma edule were reported in continuously immersed populations (Guevara & Niell 1989). Local variability in growth rate occurs in areas separated by relatively short distances within sites, e.g. Llanrhidian Sands, Wales (Hancock, 1967). Growth rates were reported to vary between years and geographical locations (Hancock, 1967; Ducrotoy et al., 1991). Growth rates decrease as population density increases probably due to increased competition for food, and direct interference or disturbance due to burrowing and direct contact between individuals (Orton, 1926; Hancock, 1967; Jensen, 1993; Montaudouin & Bachelet, 1996). Montaudouin & Bachelet (1995) reported highest juvenile growth rates at low density (160-200 adults /m²) whereas adult growth rates were only depressed at the highest density examined (2000 adults/m²). Cerastoderma edule is unable to acclimatise to low temperatures, resulting in reduced metabolic rate and oxygen consumption during winter months. However, reduced food availability in the winter months results in low or negligible growth (Smaal et al. 1997). Seasonal Growth 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). Growth banding 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). Parasitism 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,