BIOTIC Species Information for Macoma balthica
|Researched by||Lizzie Tyler||Data supplied by||University of Sheffield|
|Refereed by||This information is not refereed.|
|Reproductive Season||Spring and autumn||Reproductive Location||Insufficient information|
|Reproductive frequency||Annual episodic||Regeneration potential||No|
|Life span||6-10 years||Age at reproductive maturity|
|Generation time||1-2 years||Fecundity||30000|
|Egg/propagule size||Fertilization type||Insufficient information|
|Reproduction Preferences Additional Information||Life span
Gilbert (1973) reviewed longevity records of Macoma balthica. Life span is typically 5-10 years but may be as long as 30 years in populations from deep, cold water. The data presented suggest that maximum size and growth rate decrease and longevity increases with increasing latitude and associated cooler temperatures.
Age 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.
Gametogenesis and spawning
Caddy (1967) studied gametogenesis and spawning in a population of Macoma balthica from the Thames Estuary, UK. The primary gonad passed through a male phase, maturation being achieved in the 2nd year of life. Gametogenesis was associated with a system of follicle cells which broke down as the gametes approached maturity. The arrangement of the follicle cells was characteristic of the sex. In the female, gametocytes were peripheral to the follicle cells, while in the male they were interstitial. Spermatogenesis proceeded most rapidly in the centre of the follicle, resulting in a gradient of spermatogenic stages of increasing maturity from the periphery to the centre.
Spawning occurred principally in the spring and to a lesser extent in the autumn. Several spawnings were identified within a season, but repeated cycles of gametogenesis were absent. Ejection of eggs occurred from the exhalant siphon and continued for 40 minutes with brief spawning bursts at 3 minute intervals. Eggs were expelled at considerable speed to a height in the water column of approximately 8cm and settled out of suspension slowly. Females of approximately 17mm shell length were estimated to have expelled between 10,000 and 50,000 eggs.
|Reproduction References||Fish & Fish, 1996, Harvey & Vincent, 1989, Gilbert, 1973, Gilbert, 1978, Caddy, 1967, Lammens, 1967, Ratcliffe et al., 1981, Bonsdorff et al., 1995, Eckert, 2003, Julie Bremner, unpub data,|