辽宁沿海薄片镜蛤的繁殖周期研究

Reproductive cycle of clam Dosinia corrugata along coast of Liaoning Province

为了解薄片镜蛤Dosinia corrugata的性腺发育周期,于2013年8月—2014年7月对大连市庄河海区薄片镜蛤的繁殖周期及其与生长海区环境因子(温度、盐度、叶绿素a)的关系进行了研究。结果表明:温度和叶绿素a有明显的季节变化规律,盐度周年变化不大;组织学观察显示,薄片镜蛤周年只有一个产卵季节,6—7月配子成熟,7—8月集中排放,9月—翌年3月性腺变化很小,大部分个体处于形成期,未观察到休止期;配子成熟和排放期间,水温和叶绿素a均处于周年较高水平,性腺发育过程受温度和叶绿素a共同作用的影响;薄片镜蛤卵径随性腺发育逐渐增大,排卵前最大(56.9μm),排卵后迅速减小。研究表明,通过卵径能较为准确地判断薄片镜蛤的性腺成熟度,建议将5—8月定为薄片镜蛤的禁捕期。

The reproductive cycle of clam Dosinia corrugata and related environmental factors including temperature,salinity,and Chlorophyll a level was investigated in the coast of Liaoning Province from August of 2013 to July of 2014 to understand gonadal development of the clam.It was found that the temperature and the Chlorophyll a levels were changed with seasons,and that the salinity remained the same level as the freshwater inputs were almost negligible.Histological observation revealed that the clam spawned only once a year from July to August,gametes being matured in June and July,and released collectively in July and August,as the temperature maintained in a relatively high coinciding with phytoplankton bloom or peak Chlorophyll a levels.Gametogenesis was initiated in September and appeared to continue until March,but resting phase was not observed in this study.The development of mean diameter of the clam oocyte was characterized by a clear seasonal pattern,being increased from 22.8μm in December,to the maximum value of 56.9 μm in July before spawning,and then decreased sharply.The findings indicate that the mean oocyte diameter could be taken as an effective indicator for identifying the gonadal maturity of the clam.Thus it is recommend that from May to August be the closed fishing season of Dosinia corrugata.