| 英文摘要 |
Histologies and gonadal index’s showed that the oysters reared in the ponds had similar gonadal developments as those in the sea. In ponds, salinity being diluted to below 15 ppt might cause mass mortality of the spats(about 21 days old); survival rate of the spats(about 21 days old) reared at 32 ℃ was not lower significantly than those at 28 and 24 ℃. The cultches being hanged down below surface of water 10~60 cm there was no significant difference of density of spats among different depth; average density was1.52 spats per cultch, the highest was 12.5 spats per cultch. Density of planktonic larvae detected was about 6000 individuals per metric ton. The low density of spats might blame on predators; the possible predators collected were larvae of polychaetes, and omnivore copepoda Cyclopoida and Harpacticoida; oyster adults might filter large amount of planktonic larvae. The zygotes produced by artificial propagation and naturally occurring made similar outcomes of spats. The pond-born phytoplankton could satisfy the development of oyster larvae and the production of spats. |
