Spatial and temporal variation of planktonic larvae and juvenile of bivalve Meretrix lamarckiion on the exposed sandy beach

为了解裸桑迪海滩上文蛤（Meretrix lamarkion）浮游仔稚鱼的运动和补充的基本特征，采用野外调查和数值模拟相结合的方法进行了研究。在日本文蛤最多产的茨城县大洗海岸，对文蛤幼贝的空间分布和海滩剖面变化进行了实地调查。野外调查结果表明，秋季早期幼鱼高密度分布在海岸线附近（补充），冬季向近海迁移，春季返回海岸线。这一事实表明，文蛤幼鱼的栖息地季节性变化之间的海岸带和近海地区。本文用ALC荧光显微镜研究了海岸带短时间尺度幼鱼运动的基本特征 ...更多信息 阿克尔实验另一方面，为了了解文蛤（Meretrix lamarkiion）浮游幼虫的行为，建立了模拟浮游幼虫在外海扩散过程的数值模型。该模型由能模拟从陆架海尺度到碎波带尺度过程的水动力模型和以Higano等（1993）的实验室实验为基础的浮游幼虫模型组成。数值试验结果表明，碎波带垂向环流的重要性。由于碎波带的垂直环流，浮游幼虫被困在碎波带中，无法从碎波带流出到近海。此外，数值试验，以检查岬防御工程的影响表明，离岸流引起的岬可以流出的近岸地区的浮游幼虫。这一事实表明，岬防御工程对文蛤幼虫的扩散和补充过程有很大的影响。少

In order to understand the fundamental characteristics of movement and recruitment of planktonic larvae and juvenile of bivalve Meretrix lamarckiion on the exposed sandy beach, intensive field surveys and numerical modeling were performed in this study. In the field survey, spatial distribution of juvenile of Meretrix lamarckiion and beach profile changes were measured on the Ooarai coast in Ibaragi prefecture which is the most productive area of Meretrix lamarckiion in Japan. The field measurement results showed that the high density population of early stage juveniles distributed around the shoreline in autumn (recruitment), they moved to offshore region in winter and came back to the shoreline region in spring. This fact suggests that the juvenile of Meretrix lamarckiion seasonally change their habitat between the shoreline zone and offshore region. The fundamental characteristics of juvenile movement of short time scale in the shoreline zone were examined with the ALC fluorescent m … More arker experiment. On the other hand, in order to understand the behavior of planktonic larvae of Meretrix lamarckiion, the numerical model to simulate the dispersion process of planktonic larvae in the open coastal sea has been developed. This model consists of the hydrodynamic model which can simulate the processes from the shelf sea scale to surf zone scale, and planktonic larvae model which is based on the laboratory experiment by Higano et al, (1993). Numerical experiment results showed that the importance of surf zone vertical circulation. The planktonic larvae were trapped in the surf zone and prevented to outflow from the surf zone to offshore region due to the surf zone vertical circulation. Furthermore, the numerical experiments to examine the influence of the headland defense works showed that the offshore current induced due to the headland could outflow the planktonic larvae from the nearshore region. This fact suggests that the headland defense works have a large impact on the dispersion and recruitment process of planktonic larvae of Meretrix lamarckiion. Less