山东沿海脉红螺的性腺发育和生殖周期

为阐明脉红螺的繁殖生物学特性,于2012年3月至2013年2月对中国山东荣成靖海湾的脉红螺(Rapana venosa)的生殖周期及其与环境因子的关系进行了研究。组织学观察表明,脉红螺全年只有1个生殖周期,且雌雄配子同步发育,其性腺发育过程可分为5个时期:形成期,增殖期,成熟期,排放期,恢复期。配子发生始于9月,大部分个体在5月至6月成熟,排放的高峰期为7月。条件指数和平均卵径随配子发生而增大,成熟期达到最高值,产卵后减少。雌雄比例整体符合自然界性比为1∶1的自然规律。环境因子的分析结果表明,水温和叶绿素a含量存在明显的季节变化,而盐度无明显季节变化。相关性分析表明,水温与叶绿素a含量显著正相关(P0.05)。研究结果丰富了脉红螺的繁殖生物学资料,对脉红螺野生资源的管理保护、开发利用提供了重要的科学依据。

Gonadal maturation and the reproductive cycle of Rapana venosa along the coast of Shandong Province

The veined rapa whelk, <i>Rapana venosa</i>, (Valenciennes 1846), which is in the family Muricidae, is a large predatory marine gastropod native to the coasts of China, Korea, and Japan. In the mid-1940s, it invaded the Black Sea and is now known worldwide as a notorious invasive species. In China, <i>R. venosa</i> is an economically important molluscan species, but the wild resource has decreased dramatically in the last 20 years because of over-exploitation and deterioration of environmental conditions. Large-scale production of whelks has not been accomplished; therefore, understanding the reproductive cycle of this species is crucial for establishing aquaculture techniques for seed production. In the current study, the reproductive cycle of <i>R. venosa</i> in Jinghai Bay, Shandong Province, China was investigated from March 2012 to February 2013 in relation to environment factors. Water temperature at the sampling site showed a typical seasonal pattern of the temperate zone, with a unimodal peak in August and a minimum in January. The chlorophyll <i>a</i> concentrations exhibited a similar pattern, with a peak observed in September and a minimum in January. The chlorophyll <i>a</i> concentrations were significantly related to seawater temperature. Gonadal development of <i>R. venosa</i> was observed using tissue slices stained with hematoxylin and eosin, and the gametogenic stages were categorized into early active stage (stage I), late active stage (stage II), ripe stage (stage III), partially spawned stage (stage IV), and recovery stage (stage V). Gametogenesis was initiated in September, continued slowly during the winter, followed by rapid gonad development during spring and summer. Most individuals were ripe between May-June, and gametes were released May-August. The spawning peak occurred in July, and the gonads recovered August-November. <i>R. venosa</i> had synchronized gonadal development in both sexes, and no hermaphrodites were found. Among 1093 specimens, 552 were females and 541 were males, resulting in a balanced sex ratio. The condition index and oocyte diameter clearly varied seasonally; increased at the beginning of gametogenesis, reached a peak at gonad maturity, and then declined after gamete release. This is the first study to establish the gametogenic pattern of <i>R. venosa </i>along on the coast of Shandong Province, China. The data obtained from this study will be useful for sustainable management of wild stocks and future aquaculture of this species.