BIOTIC Species Information for Mya arenaria
|Researched by||Lizzie Tyler||Data supplied by||University of Sheffield|
|Refereed by||This information is not refereed.|
|Scientific name||Mya arenaria||Common name||Sand gaper|
|MCS Code||W2149||Recent Synonyms||None|
|Additional Information||Common names include, the 'sand gaper', 'soft clam', 'soft-shelled clam', 'steamer clam' and the 'nannynose'. The literature on Mya arenaria is extensive and this Key Information review is based upon more detailed reviews by Clay (1966), Newell & Hidu (1986) and Strasser (1999).|
|Taxonomy References||Fish & Fish, 1996, Howson & Picton, 1997, Campbell, 1994, Hayward et al., 1996, Tebble, 1976, Foster-Smith, 2000, Turk & Seaward, 1997, Allen, 1962, Bruce et al., 1963, Newell & Hidu, 1986, Strasser, 1999, Clay, 1966, Anonymous, 1996, Hawkins, 1994,|
||Feeding method||Passive suspension feeder
Active suspension feeder
|Typical food types||Phytoplankton, small zooplankton, benthic diatoms, suspended particulates and dissolved organic matter.||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||Mya arenaria populations demonstrate pronounced patchiness, e.g. in the Dutch Wadden Sea its abundance varies from high to low. Patchiness seems to be typical in Mya arenaria and has been reported from Sweden and North America (Strasser et al.,1999; Strasser pers. comm.).
Growth rates: Mya arenaria generally grows fastest in its first years with growth rate decreasing with age, although linear rates of growth have also been reported (Strasser, 1999). Growth is rapid in favourable conditions but rates vary with location, e.g. Mya sp. grew to 51 mm in 6-7 years in Alaska, but this size was attained in 1.5 years in Connecticut (Brousseau & Baglivo, 1987). Similarly, marketable size ( 4-5 cm long) was reached within 1.5 years in Chesapeake Bay, but took 5 years in New Brunswick, Canada. Growth rates are affected by population density, sediment type, salinity, emergence time, water flow rates, disturbance, latitude and pollution (Newell & Hidu, 1986; Strasser, 1999).Seasonal growth rates: growth is generally greatest in late spring and early summer and slowest in cold winters e.g. in New England (Newell & Hidu, 1986). Rapid growth is correlated with the phytoplankton bloom and therefore food availability but may also be affected by temperature and spawning (Stickney, 1964; Brousseau, 1979; Newell & Hidu, 1986).
|Biology References||Fish & Fish, 1996, Campbell, 1994, Hayward et al., 1996, Tebble, 1976, Newell & Hidu, 1986, Strasser, 1999, Brousseau & Baglivo, 1987, Brousseau, 1979, Stickney, 1964, Clay, 1966, Brousseau, 1987, Newell, 1982, Armonies, 1994, Brousseau, 1978(b), Kühl, 1981, Gibbons & Blogoslawski, 1989, Anonymous, 1996, Hawkins, 1994, Kammermans, 1994, Dow & Wallace, 1961, Beukema, 1995, McLaughlin & Faisal, 2000, Hayward & Ryland, 1990,|
|Distribution and Habitat|
|Distribution in Britain & Ireland||Found on all British coasts but is not recorded from the Isles of Scilly.|
|Global distribution||Found on the European coast from the White Sea to northern Norway, in the Baltic Sea and Wadden Sea to Portugal as well as the Black Sea. Reported from Labrador to Georgia in the W. Atlantic and from North Sound, Alaska to California in the E. Pacific.|
|Biogeographic range||Not researched||Depth range||0 - 20 m|
|Migratory||Non-migratory / Resident|
|Distribution Additional Information||The southern distribution of Mya arenaria may be restricted by a limit of 28 °C for both adults and larvae (Newell & Hidu, 1986; Strasser, 1999). Various authors suggested that the northern distribution was limited by critical spawning temperature of 10-12 °C and 12-15 °C required for larval development, however, Strasser (1999) noted some exceptions and concluded that this hypothesis needed further examination.
Distribution: Mya arenaria is found most abundantly in intertidal and shallow subtidal areas but can reach 192 m depth in the subtidal (Strasser, 1999). The majority of clams >50 mm are found in sediment between 15 - 20 cm deep in the Wadden Sea, but may burrow up to 40 cm deep. As they grow adults live deeper in the sediment, their siphons growing accordingly and large clams establish a permanent burrow. Young clams (up to 50 mm) can burrow again if disturbed. However the foot becomes much reduced and shorter in larger specimens. With increasing size it becomes more difficult for exposed specimens to raise the shell into position and therefore. if disturbed, fewer large than small individuals manage to reburrow. For example, 62% of small clams (35-50mm), 39% of medium sized (51-65 mm) and only 21% of large clams (66-75 mm) had reburrowed within 48 hours (Pfitzenmeyer & Drobeck, 1967).Mya arenaria grows faster in fine rather than coarse sediments and fastest in sand or sandy mud. The clam has difficulty burrowing in sediments larger than 0.5 mm (coarse sand). Areas with fast currents support highest densities and growth rates whereas excessive silt reduces growth rates (Newell & Hidu, 1986). Densities of adults vary between years and location, e.g. Clay (1966) reported adult densities between ca 5 /m² to 300 /m² in the UK and Strasser et al. (1999) reported abundances between 0-243 individuals /m² (with a mean of 11.8 individuals /m²) in the Wadden Sea. Strasser et al. (1999) concluded that the Wadden Sea population is greatest at the mid to low tidal level and resulted from larval settlement. Its patchy distribution and dominance of single year classes being due to wind direction during peaks of larval settlement, and when juvenile predation is low. Clams that survive the first year may reach several years of age but mass mortalities may occur at any time, due to indeterminate causes (Strasser et al, 1999).
Global distribution: Mya arenaria became extinct on the east coasts of the Pacific and Atlantic during the glaciations of the Pleistocene. It subsequently colonized the European coast between the 13 th and 17 th centuries, possibly introduced by the Vikings (as food or bait) (Eno et al., 1997; Eno et al., 2000; Strasser, 1999). Mya arenaria has been reported from Kamchatka to southern Japan and China, however these records may have been confused with Mya japonica (Strasser, 1999). Strasser (1999) also regarded additional records from Iceland, the Mediterranean and Florida as dubious. Mya arenaria probably invaded the Pacific east coast as a by-product of oyster transplants but was later intentionally introduced as a commercial fishery. It was probably introduced into the Black Sea around 1960 as larvae in the ballast waters of Baltic Sea tankers (Strasser, 1999) . Strasser (1999) notes that although introduction may have been effected by man its present distribution is also the result of significant natural expansion.
|Substratum preferences||Muddy gravel
Coarse clean sand
Fine clean sand
|Physiographic preferences||Strait / sound
Ria / Voe
Enclosed coast / Embayment
|Biological zone||Mid Eulittoral
|Tidal stream strength/Water flow||Moderately Strong (1-3 kn)
Weak (<1 kn)
|Salinity||Full (30-40 psu)
Low (<18 psu)
Reduced (18-30 psu)
Variable (18-40 psu)
|Habitat Preferences Additional Information|
|Distribution References||Fish & Fish, 1996, Campbell, 1994, Hayward et al., 1996, Tebble, 1976, Foster-Smith, 2000, Turk & Seaward, 1997, Crothers, 1966, Allen, 1962, Seaward, 1982, Seaward, 1990, Bruce et al., 1963, Newell & Hidu, 1986, Strasser, 1999, Eno et al., 1997, Clay, 1966, Newell, 1982, Armonies, 1994, Kühl, 1981, Anonymous, 1996, Strasser et al., 1999, Hawkins, 1994, Dow & Wallace, 1961, Pfitzenmeyer & Drobeck, 1967, Hayward & Ryland, 1990,|
|Reproductive Season||See additional information||Reproductive Location||Water column|
|Reproductive frequency||Annual protracted||Regeneration potential||No|
|Life span||11-20 years||Age at reproductive maturity||3-5 years|
|Generation time||3-5 years||Fecundity||100000- 5000000|
|Egg/propagule size||66 µm diameter||Fertilization type||External|
|Reproduction Preferences Additional Information||A life span of 10-12 years was considered normal, although a maximum of 28 years was recorded in the Bay of Fundy (Strasser, 1999). Commito (1982) suggested that Mya sp. delayed reproduction until its fourth year, preferring rapid growth to reach a depth refuge. Strasser (1999) reported that first reproduction usually occurred at a size of about 20 -50 mm, which corresponds to an age of about 1-4 years depending on growth conditions.
Spawning: Spawning occurs once or twice annually, usually starting in spring and can occur between March and November depending on locality. In European waters larvae are usually found in May and June but sometimes as late as October. Annual spawning was reported in the Wadden Sea, on the west coast of Sweden, the east coast of Denmark and the Black Sea whereas biannual spawning was reported in Oslofjord and the south coast of England (Warwick & Price, 1976; Strasser, 1999; and see Brousseau,1987 and Clay, 1966 for reviews).
Both temperature and food availability affect gametogenesis and spawning. Critical spawning temperatures of 10-12 °C were suggested by Nelson (1928) however, peak spawning occurs in Massachusetts at 4-6 °C (Brousseau, 1978a). Peaks of larvae have been observed at 20°C and second spawnings once temperature had dropped below 25 °C (Newell & Hidu, 1986). Optimum larval growth has been reported between 17 -23 °C in the laboratory (Stickney, 1964) and slow growth between 12-15 °C (Loonsanoff & Davis, 1963). Strasser (1999) suggested that further study was required.
Fecundity: Males usually spawn first, releasing a pheromone which stimulates females to spawn (Newell & Hidu, 1986). Fecundity varies with location and size e.g. 120,000 eggs from a 60 mm clam, 3 million from a 63 mm clam and 1-5 million eggs in an individual have been reported (Strasser, 1999).
Fertilization: fertilization is external. Eggs are 66µm in diameter and can be carried many miles by the current (Newell & Hidu, 1986).
Larval stages: larval life lasts about 2-3 weeks, but can be extended, in the laboratory to up to 35 days in unfavourable conditions, most not metamorphosing until 200µm in length (Loosanoff & Davis, 1963; Strasser, 1999).
Recruitment: recruitment in bivalve molluscs is influenced by larval and post-settlement mortality. Mya arenaria demonstrates high fecundity, increasing with female size, with long life and hence high reproductive potential. The high potential population increase is offset by high larval and juvenile mortality. Juvenile mortality reduces rapidly with age (Brousseau, 1978b; Strasser, 1999). Larval mortality results from predation during its pelagic stages, predation from suspension feeding macrofauna (including conspecific adults) during settlement and deposition in unsuitable habitats. Mortality of the juveniles of marine benthic invertebrates can exceed 30% in the first day, and several studies report 90% mortality (Gosselin & Qian, 1997). Larval supply and settlement is often dependant on currents and timing of the phytoplankton bloom and may be sporadic in bivalves (see Cerastoderma edule reproduction) and differs consistently between sites. Recruitment is affected by adult population density, settlement intensity (in some but not all cases), post-settlement and juvenile predation, active and passive transport, and bedload transport or sediment erosion (Olafsson et al., 1994). For example:
|Reproduction References||Newell & Hidu, 1986, Strasser, 1999, Brousseau & Baglivo, 1987, Brousseau, 1979, Stickney, 1964, Clay, 1966, Brousseau, 1987, Warwick & Price, 1975, Brousseau, 1978(a), Loosanoff et al., 1966, Loosanoff & Davis, 1963, Lutz et al., 1982, Emerson & Grant, 1991, Gosselin & Qian, 1997, Brousseau, 1978(b), Kühl, 1981, Anonymous, 1996, Strasser et al., 1999, Hawkins, 1994, Dow & Wallace, 1961, Nelson, 1928, Olafsson et al., 1994., Commito, 1982, Eckert, 2003, Brousseau, 1978(b), Strasser, 1999,|