BIOTIC Species Information for Spisula solida
|Researched by||Lizzie Tyler||Data supplied by||University of Sheffield|
|Refereed by||This information is not refereed.|
|Scientific name||Spisula solida||Common name||Thick trough shell|
|MCS Code||W1977||Recent Synonyms||None|
|Additional Information||Spisula solida may be confused with Spisula elliptica, however the latter is smaller and more delicate. Spisula elliptica is also narrower relative to its length. Spisula solida may also be confused with Mactra stultorum but the cardinal teeth of the latter are smooth rather than ridged. Please note: the biology of Spisula solida is poorly known and information on closely related species has been used where appropriate.|
|Taxonomy References||Howson & Picton, 1997, Tebble, 1976, Gibson et al., 2001, Fish & Fish, 1996,|
||Feeding method||Passive suspension feeder
Active suspension feeder
|Typical food types||Phytoplankton (i.e. diatoms)||Habit||Burrow dwelling|
|Bioturbator||Flexibility||None (< 10 degrees)|
|Height||Insufficient information||Growth Rate||See additional information|
|Adult dispersal potential||100-1000m||Dependency||Independent|
|General Biology Additional Information||Abundance and biomass
The abundance of Spisula solida varies with location. For example, the following abundances and biomass were reported:
The maximum length of Spisula solida (5 cm) from Irish waters is similar to that of northern European stocks but growth rates appear to vary geographically. Dimensions attained by Irish Spisula solida differ from those reported from other northern European stocks of the species. In the Danish North Sea, individuals between 2-3 years reached a length of 35 mm. Meixner (1994; cited in Fahy et al., 2003) reported that Spisula solida 35 mm in length from the German North Sea similarly averaged 2.5 years old while in Waterford Harbour individuals were 5.27 years at the same length (Fahy et al., 2003).
|Biology References||Kristensen, 1996, Ford, 1925, Gaspar et al.,1995, Weinberg & Helser, 1996, Hayward & Ryland, 1990,|
|Distribution and Habitat|
|Distribution in Britain & Ireland||Recorded at scattered locations around the coasts of Britain and Ireland.|
|Global distribution||Spisula solida is distributed from subarctic Iceland and Norway as far south as Portugal and Morocco but is not found in the Mediterranean.|
|Biogeographic range||Not researched||Depth range|
|Migratory||Non-migratory / Resident|
|Distribution Additional Information||Kristensen (1996) reported that Spisula solida showed a preference for grain sizes that ranged between 2-3 mm. The population of Spisula solida in Waterford Harbour, (Ireland) conformed to the grain size preference above. Spisula solida can be found at depths of 50 m (Schlieper et al., 1967). But in the North Sea, Spisula solida is restricted to depths of about 10-15 m (Theede et al., 1969). Whereas, in Portuguese waters, Spisula solida is more common in greater abundances at depths between 5-13 metres (Gaspar et al., 1999).|
Gravel / shingle
Fine clean sand
|Physiographic preferences||Open coast
Strait / sound
|Biological zone||Lower Eulittoral
|Wave exposure||Very Exposed
|Tidal stream strength/Water flow||Strong (3-6 kn)
Moderately Strong (1-3 kn)
Weak (<1 kn)
|Salinity||Full (30-40 psu)
|Habitat Preferences Additional Information|
|Distribution References||Tebble, 1976, Gibson et al., 2001, NBN, 2002, Picton & Costello, 1998, JNCC, 1999, Theede et al., 1969, Schlieper et al., 1967, Hayward & Ryland, 1990,|
|Reproductive Season||February to June||Reproductive Location||Insufficient information|
|Reproductive frequency||Annual protracted||Regeneration potential||No|
|Life span||6-10 years||Age at reproductive maturity||1 year|
|Generation time||Insufficient information||Fecundity|
|Egg/propagule size||Fertilization type||Insufficient information|
|Reproduction Preferences Additional Information||Longevity
The life expectancy of Spisula solida is up to approximately ten years (Fahy, 2003).
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).
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 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).
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).
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,|