BIOTIC

BIOTIC Species Information for Spisula solida

Researched by

Lizzie Tyler

Data supplied by

University of Sheffield

Refereed by

This information is not refereed.

Reproduction/Life History

Reproductive type

Gonochoristic

Developmental mechanism

Planktotrophic

Reproductive Season

February to June

Reproductive Location

Insufficient information

Reproductive frequency

Annual protracted

Regeneration potential

Life span

6-10 years

Age at reproductive maturity

1 year

Generation time

Insufficient information

Fecundity

Egg/propagule size

Fertilization type

Insufficient information

Larvae/Juveniles
Larval/Juvenile dispersal potential	Insufficient information	Larval settlement period	Insufficient information
Duration of larval stage

Reproduction Preferences Additional Information

Longevity
The life expectancy of Spisula solida is up to approximately ten years (Fahy, 2003).

Sexual maturity
Spisula solida reaches sexual maturity during its first year, which is a function of age, not of size (Gaspar & Monteiro,1999; Fahy et al., 2003).

Gametogenesis
The sexes of Spisula solida are separate and there are no records of hermaphrodites (Gaspar & Monteiro, 1999). Male and female white clams are distinguishable externally since the colour of the gonad in this species is reddish in the females and yellowish-orange in the males (Gaspar & Monteiro, 1999). Both sexes show a synchrony in gametogenic development and spawning.

Gaspar & Monteiro (1999) observed that gametogenesis in Spisula solida began when the seawater temperature started to decrease (late September). Gaspar et al. (1999) concluded that the initiation of gametogenesis in Spisula solida was a response to falling temperature and that spawning occurred when the temperature began to rise rather than occurring at a fixed temperature. The maturation of the gonad continued until late January when the water temperature was at its lowest (Gaspar & Monteiro, 1999). In Danish waters specimens of Spisula solida were sexually inactive from July-Sept. The first ripe stage of gonads was reached in December, and all individuals were ripe by January (Gaspar & Monteiro, 1999).

Spawning
Spawning begins in February (Gaspar & Monteiro, 1999). Gaspar & Monteiro (1999) noted that 75% of a studied population were in the spent stage of their gametogenic cycle by June (Gaspar & Monteiro, 1999).
Dispersal
Ford (1925) suggested that Spisula solida can be moved along by water movement (bed load transport) along the sea bottom to another position on the seabed. Therefore, in the course of time considerable mixing could easily bring together individuals of different ages and origins (Ford, 1925).
Recruitment
In Ireland the recruitment of Spisula solida is irregular with 1 year old clams out numbering all the other year classes (Fahy et al., 2003). The reasons for this are unknown. However, irregular settlement rather than erratic gamete production might be the explanation for the occasional strong representation of a year class in Waterford Harbour clam population (Fahy, 2003).

Reproduction References

Gaspar & Monteiro, 1999, Ford, 1925, Fahy, 2003, Fahy et al., 2003,