BIOTIC

BIOTIC Species Information for Macoma balthica
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 Surface deposit feeder Sub-surface deposit feeder
Mobility/Movement	Crawler Burrower	Environmental position	Infaunal
Typical food types	Diatoms, deposited plankton, suspended phytoplankton & detritus.	Habit	Burrow dwelling
Bioturbator		Flexibility	None (< 10 degrees)
Fragility	Intermediate	Size	Small(1-2cm)
Height	Insufficient information	Growth Rate	3 mm/year
Adult dispersal potential	100-1000m	Dependency	Independent
Sociability	Solitary
Toxic/Poisonous?	No
General Biology Additional Information	Abundance Stephen (1929) reported typical abundances of Macoma balthica from the Firth of Forth to be 0-89/m² and maximum abundance to be 288/m². Ratcliffe et al. (1981) reported adult densities in the Humber Estuary, UK, between 5,000/m² and 40,000/m² depending on time since a successful spatfall. Bonsdorff et al. (1995) reported juvenile density in the Baltic Sea following settlement to be 300,000/m² decreasing to a stable adult density of 1,000/m². Size at maturity Caddy (1967) reported Macoma balthica from the River Thames reaching maturity in their 2nd year at a size of 5-6mm, whereas in the Netherlands, first year animals larger than 4mm had developed gonads during the spawning season (Lammens, 1967). Lavoie (1970) (cited in Gilbert, 1978) reported that a population of Macoma balthica from a French estuary did not achieve sexual maturity until their second year at a mean length of 3.57mm. Given that the growth rate varies significantly between populations, Gilbert (1978) suggested that Macoma balthica may mature in its 2nd year of life regardless of size or during its first year if a certain size is achieved. Harvey & Vincent (1989), however, consider that sexual maturity is a function of size rather than age in Macoma balthica, maturation occurring when the shell reaches 6mm with corresponding ages of individuals from the same population varying between 10 and 22 months. Growth rate Gilbert (1973) reported mean annual growth rate of Macoma balthica to be 3.3mm/yr with an average length of 18-20mm for fully grown individuals. However, other studies show considerable variations in growth patterns in relation to habitat and depth. McLusky & Allan (1976) reported the maximum growth rate of Macoma balthica in the laboratory to be 1mm over an 8 month period for 5-7mm long animals maintained at 15°C and 25psu. Toxicity Macoma balthica is not normally considered to be toxic but may transfer toxicants through the food chain to predators. Macoma balthica was implicated in the Mersey bird kill in the late 1970's, owing to bioconcentration of alklyC-lead residues (Bull et al., 1983).
Biology References	Fish & Fish, 1996, Bonsdorff, 1984, Harvey & Vincent, 1989, McLusky & Allan, 1976, Brafield & Newell, 1961, Clay, 1967(b), Stephen, 1929, Gilbert, 1973, Gilbert, 1978, Caddy, 1967, Lammens, 1967, Ratcliffe et al., 1981, Bonsdorff et al., 1995, Tebble, 1976, Bull et al., 1983, Hayward & Ryland, 1990, Julie Bremner, unpub data,