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The reproductive biology of the Japanese Littleneck, Tapes philippinarum (A. Adams and Reeve, 1850) (Bivalvia: Veneridae)
Ponurovsky, S.K.; Yakovlev, Y.M. (1992). The reproductive biology of the Japanese Littleneck, Tapes philippinarum (A. Adams and Reeve, 1850) (Bivalvia: Veneridae). J. Shellfish Res. 11(2): 265-277
In: Journal of Shellfish Research. National Shellfisheries Association: Duxbury. ISSN 0730-8000; e-ISSN 1943-6319
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| Author keywords |
clams, Tapes philipinarum, development , populations, hermaphroditism, Sea of Japan , South Primorye |
| Auteurs | | Top |
- Ponurovsky, S.K.
- Yakovlev, Y.M.
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| Abstract |
A study was undertaken of natural populations of Manila clams (Japanese littleneck clams), Tapes philippinarum, from five bays and inlets in the northwestem part of the Sea of Japan. Seasonal gonadal changes were observed histologically in samples of Manila clams collected from Vostok Bay between January and December 1985 . Five stages of gonadal development were identified . The first stage was the Active Stage of growth and maturation. At the beginning of this stage the gonad was poorly developed. In April, gametogenic activity increased and a spreading system of follicles was observed in the gonad. Along with developing gametes in the follicles there were blood cells and reserve tissue. This stage ended in June. In the Ripe Stage, the gametes matured. The female gonad was filled with mature oocytes that measured 64 μm in diameter. The male follicles were filled with spermatozoa that formed strands. Spawning usually began in mid to late June when water temperatures reached 15- 16°C. Most individuals spawned in July and August during which time the Partially Spent Stage of the gonad was observed. Spawning was nearly completed by October when water temperatures declined to 15°C. The Spent Stage was characterized by spent follicles that sometimes contained residual gametes. Individuals in this stage were seen until October. The final stage was the Resting Stage which was seen in November and December. During this stage resorption of residual gametes occurred. Manila clams became sexually mature during the first year of life at a minimum shell length of 7- 8 mm, however, this varied among populations . The sex ratio of most populations sampled was close to 1:1. Hermaphroditism and parasitic castration are described. |
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