青岛岩相潮间带短滨螺种群动态的研究

STUDY ON POPULATION DYNAMICS OF LITTOR1NA BREVICULA ON ROCKY SHORE IN QINGDAO, CHINA

于1987年2月—1988年1月在青岛太平湾岩相潮间带高、中、低潮区定量采样和现场观察,利用微机分析各月不同潮区短滨螺种群结构和数量动态。结果表明,短滨螺在潮间带呈垂直成带分布:由低向高,短滨螺种群平均体高和生物量依次减小,栖息密度依次增大;2月中旬—4月下旬是短滨螺持续排卵期,12月开始,成熟的短滨螺向低潮区迁移,为繁殖做准备并交配;交配后,雄性向上迁移,而雌性却依赖潮间带底部水环境作为排卵场所,从而使低、中潮区2月份性比不平衡,雌性个体多于雄性。5—11月,低潮区无短滨螺分布,捕食者对短滨螺的捕食和浪击作用是抑制短滨螺在低潮区分布的重要环境因子。

Monthly quantitative-samplings and investigations of Littorina brevicula at the high intertidal region (HIR), middle intertidal region(MIR) and low intertidal region(LIR) were carried out from February, 1987 to January, 1988 on the rocky shore of Taiping Bay, Qingdao. Computer-aided monthly analyses of shell height pattern, dwelling-density, biomass and sex-ratio of L. brevicula at different intertidal regions were carried out. About 200 L. brevicula individuals and rocks in the intertidal zone were transferred to an aquarium in order to investigate the vertical distribution changes of L. brevicula when there is no predation and/or wave action on it for a long time. The results indicate that:(1) L. brevicula presents vertical gradient zonation on rocky shore. The average shell height and biomass decrease, and dwelling-density increases from LIR to HIR.(2) L. brevicula has great adaptative capacity to the amphibious intertidal environment and can live out of water for 20 days without food. In summer, they assemble in the shape of a to-wer to prevent water lose from their bodies.(3) L. brevicula migrate vertically during different months. During the reproduction season (from February to April), adults migrate downwards to get enough food and release eggs into water. After intercourse, males migrate upwards, but females stay in the lower part of the intertidal zone to release eggs into water, so that females obviously outnumber males at the LIR and MIR in February. The vertical migration and recruitment of L. brevicula cause fluctuations of the average shell heights, biomasses and dwelling-densities of L. brevicula populations in different intertidal regions.(4) From May to November, there are no L. brevicula in the LIR. But in laboratory, the predation and wave action on L. brevicula are eliminated and they can live in the water environment at the bottom of rocks. This indicates that predation and wave action play a very important role in affecting the vertical distribution of L. brevicula.