莱州湾海域小刀蛏(Cultellus attenuatus)繁殖生物学研究

The Reproductive Biology of Cultellus attenuatus in the Laizhou Bay

2013年4月–2014年3月,采用组织学和实验生态学方法研究了山东莱州湾海域小刀蛏(Cultellus attenuatus)的性腺发育、生殖周期、胚胎及幼虫发育。结果显示,在繁殖季节,小刀蛏性别可通过性腺颜色区分,雌性为白色,雄性为黄色;1个生殖周期为1年,性腺发育经历增殖期、生长期、成熟期、排放期和休止期5个阶段;莱州湾繁殖期为6月中旬–7月上旬。小刀蛏受精卵卵径为50–55μm,在水温26℃、盐度28的条件下,经24 h发育至D形幼虫,10 d后幼虫发育变态为稚贝。对莱州湾小刀蛏繁殖生物学的研究,可为该海域小刀蛏的人工育苗和增养殖提供科学依据。

Cultellus attenuatus is a commercially valuable species that is widely distributed in the north and south coastal waters of China. In this study, we applied histological sectioning and experimental ecology methods to study the reproductive biology of C. attenuatus including the reproductive cycle, gonadal development, breeding season, embryonic development and larval development. Experimental subjects were collected from the Laizhou Bay of Shandong Province in the North China. C. attenuatus were sampled three times per month from May to July, and was sampled once a month in the rest months from April 2013 to March 2014. The results showed that C. attenuatus was dioecious, and that the sex could be identified with the colors of mature gonads that were white and yellow for the female and the male gonads respectively. The reproductive cycle of C. attenuatus was one year. The gonad of C. attenuatus was composed of the follicle, gonaduct and gonadial tube. The gonadal development could be divided into five stages, which were the proliferation stage in March, the increasing stage in April, the mature stage from May to early June, the breeding stage from mid-June to early July, and the suspension stage from mid-July to February of the next year. Its breeding season was between mid-June and early July when the water temperature was 22.0–26.6℃. The diameters of fertilized eggs were 50–55 μm. Hatching and the larval culture were conducted with aeration at a stable temperature and salinity. At 26℃ and salinity 28, the D-shaped larvae were hatched in 24 hours to the size of 90 μm×60 μm. Since Day 10, the larvae began to settle down and developed into the post larvae, and metamorphosis was completed. It was found that the C. attenuatus had high tolerance to air exposure. No mortality occurred when the razor shells were exposed to air at 20℃ for 12 h. Our study provided useful information for the artificial breeding of C. attenuatus.