BIOTIC Species Information for Arctica islandica
|Researched by||Lizzie Tyler||Data supplied by||University of Sheffield|
|Refereed by||This information is not refereed.|
|Reproductive Season||June to October||Reproductive Location||Water column|
|Reproductive frequency||Annual episodic||Regeneration potential||No|
|Life span||100+ years||Age at reproductive maturity||11-20 years|
|Generation time||11-20 years||Fecundity|
|Egg/propagule size||85 µm diameter||Fertilization type||External|
|Reproduction Preferences Additional Information||
Sexual maturity is reached in Arctica islandica at a later age than has been reported for other bivalves. The age at sexual maturity in Arctica islandica was reported to vary between 5 and 11 years and may be dependent upon growth rate and locality (Thorarinsdóttir, 1999) . The mean age of sexual maturity in Nova Scotia was estimated to be 13.1 years for males and 12.5 years for females (Rowell et al. 1990; cited in Cargnelli et al., 1999a). However, Thompson et al. (1980b) reported immature individuals ranging in age from 4 -14 yr., at shell lengths ranging from 2.4 - 4.7 cm. It was suggested that immature Arctica islandica physiologically mimic the reproductive cycle of adults without providing gametes but very little research has been done on annual cycles of reproduction in juveniles (Thompson et al., 1980b).
Thorarinsdóttir (2000) examined the gametogenic cycle of Arctica islandica from Iceland and suggests that there are five phases in Arctica islandica's gametogenic cycle (Thorarinsdóttir, 2000).
SpawningSpawning is protracted. Loosanoff (1953) reported spawning off Rhode Island between late June or early July when water temperatures reach 13.3 °C, although not all individuals reach ripeness at the same time. The majority of individuals completed spawning by early October. The optimum salinity range for the existence and reproduction of Arctica islandica is between 31.0 - 32.8 ppt (Loosanoff, 1953). However, the spawning period varies with location, for example another study reported spawning between May to November off Rhode Island, while spawning was reported to occur between September and November, and sometimes persisting into January off New Jersey, and between July to September off Nova Scotia (see Cargnelli et al., 1999a). Comparable data for northwest European populations is scarce. Attempts to ripen specimens of Arctica islandica out of season in the laboratory have had no or very limited success (Loosanoff, 1953; Landers, 1976). The average size of a fertilized egg is 75-95 µm (Loosanoff, 1953; Lutz et al., 1982).
Larval Settling Time
The settlement of larvae may occur over several months and is believed to occur throughout the adult distribution ranges.
The recruitment of this bivalve is considered as very sporadic (Thorarinsdóttir, 1999). Age frequency distributions from a population in Iceland showed recruitment increased at approximately 20 year intervals. A population of the Atlantic coast of the United States did not show any sign of recruitment over a 10 year period (Thorarinsdóttir, 1999).
Arctica islandica is exceptionally long lived. Growth is relatively fast during the juvenile stage and then slows down (Cargnelli et al., 1999a). Counts of internal growth lines suggested ages of 200 years for individuals living on the U.S. Atlantic coast (Ropes, 1985)
|Reproduction References||Loosanoff, 1953, Rees & Dare, 1993, Thorarinsdóttir, 2000, Cargnelli et al., 1999a, Thompson et al., 1980b, Thompson et al., 1980a, Thorarinsdóttir, 1999, Landers, 1976, Ropes, 1985, Eckert, 2003, Julie Bremner, unpub data, Rees & Dare, 1993, Kilada, 2007,|