BIOTIC Species Information for Abra alba
|Researched by||Lizzie Tyler||Data supplied by||University of Sheffield|
|Refereed by||This information is not refereed.|
|Reproductive Season||February to Autumn||Reproductive Location||Water column|
|Reproductive frequency||Annual protracted||Regeneration potential||No|
|Life span||1-2 years||Age at reproductive maturity|
|Generation time||<1 year||Fecundity||17000|
|Egg/propagule size||60 µm diameter||Fertilization type||External|
|Reproduction Preferences Additional Information||Gametogenesis
Dewarumez (1979) and Nott (1980) described the anatomy of the gonads of Abra alba and changes in the gonad condition during the reproductive cycle.
Fertilization and metamorphosis
The sexes are separate and may be distinguished microscopically by dissection. Nott (1980) estimated the number of eggs produced from an average sized animal 11 mm in length to be between 15,000 - 17,000 of 60 µm diameter. Gametes are shed within the shell cavity and swept out through the exhalent siphon by pumping, so that fertilization occurs externally. The eggs develop into free-swimming trochophore and then veliger larvae. The larval stage is planktonic, and in Abra alba, lasts about a month (Dauvin & Gentil, 1989). Larvae are subject to very high mortality. At metamorphosis, the larvae settle out of the plankton and the bivalve spends its remaining life as a member of the benthos (Dame, 1996).
Recruitment varies between localities. In a population of Abra alba from the Irish Sea, proliferation of the gonads commenced in March and the animals reached maturity between June and September. The exact time at which maturity was attained depended upon the size of the individual, but it seemed that only individuals with a minimum shell length of between 7-9 mm reproduced (Nott, 1980). Normally, there two distinct spawning periods in summer and autumn, and according to the season of settlement, individuals differ in terms of growth and potential life span. Although peak recruitment usually occurs in summer (Dauvin & Gentil, 1989).
|Reproduction References||Nott, 1980, Dauvin & Gentil, 1989, Dame, 1996, Jensen, 1988, Rees & Dare, 1993, Rainer, 1985, Warwick & George, 1980, Dewarumez, 1979,|