钝缀锦蛤繁殖周期和胚胎发育

2013年8月至2014年7月,采用组织学和实验生态学方法对钝缀锦蛤(Tapes conspersus)的性腺发育、生殖周期、肥满度、胚胎和幼虫发育进行了研究。结果显示,钝缀锦蛤性腺发育以1年为1个周期,性腺发育过程可分为增殖期、生长期、成熟期、排放期和休止期5个时期;繁殖期在每年10月至翌年3月,繁殖盛期为3月、10月和11月(水温20.3~24.6℃),分批产卵。8月肥满度最高,为33.43%;4月最低,为18.31%。钝缀锦蛤卵径为70~80μm;在水温24~26℃、盐度28~32条件下,受精卵经16 h左右发育为D形幼虫;初孵D形幼虫大小为90~110μm,浮游幼虫经7~8 d培育进入附着变态期,此时壳长为210~230μm,再经4~5 d发育变态为稚贝。本研究为钝缀锦蛤的人工繁育及种质资源保护和利用提供了基础资料。

The reproductive cycle and embryonic development of the bivalve mollusk Tapes conspersus

The marine bivalve molluskTapes conspersus is mainly distributed in tropical and subtropical waters of the southwestern Pacific Ocean, including coastal areas of China, Japan, Philippines, India, Indonesia, Australia and New Zealand. The species is relatively new to shellfish mariculture, having potentially high economic value and good prospects for development. This study used biological productivity methods to investigate the species' reproductive cycle, gonad development, fatness, breeding season, embryo development and larval development in the period from August 2013 to July 2014. In the examination of its breeding cycle, the gonadogenesis ofT. conspersus presented a unimodal gametogenic cycle, with one spawning season annually. The gonad development of the species could be divided into five stages: proliferating stage, growing stage, maturing stage, spawning stage and resting stage. This shellfish's mode of reproduction is oviparity, with a slightly greater gonad development among males than female. The species displays gonochorism, with a female to male ratio of 1:1. The spawning season was recorded as from October to March. Peaks in spawning occurred in March, October and November, at water temperatures of 20.3?24.6℃. Fatness peaked at 33.43% in August, and the lowest measure of fatness was in April at ~18.31%. The cultivation of embryos and larvae revealed demersal, elliptically shaped eggs, and the egg diameter ranged from 70 to 80μm. Under the conditions of water temperatures of 24?26℃ and salinities of 28?32, the fertilized eggs developed into D-shaped larvae, 90?110μm in length, within 16 hours of hatching. After 7?8 days, the D-shaped larvae then developed into late-umbo larvae, 210?230μm in length. Thereafter, the late-umbo larvae developed into juvenile mollusks within 4?5 days. These observations provide a foundation for the artificial breeding and protection of genetic resources ofT. conspersus.