BIOTIC Species Information for Mya arenaria
|Researched by||Lizzie Tyler||Data supplied by||University of Sheffield|
|Refereed by||This information is not refereed.|
|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,|