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

为了理解运动的基本特点和招聘浮游幼虫和青少年的双壳类文蛤lamarckiion暴露的沙滩上,密集的实地调查,进行了数值模拟研究。野外调查中，在日本青鱼最多产的茨城县上井海岸，测量了青鱼幼鱼的空间分布和海滩剖面变化。野外测量结果表明，早期幼鱼种群密度较高，秋季（捕集）分布在岸线周围，冬季迁移至近海，春季返回岸线区域。这一事实表明，蓝纹幼鱼的栖息地在岸线区和近海区之间有季节性的变化。用ALC荧光实验研究了滨岸带短时间尺度幼鱼运动的基本特征。另一方面，为了更好地了解蓝纹细纹浮游生物幼虫的行为，建立了滨海开阔海域浮游生物幼虫扩散过程的数值模拟模型。该模型包括可以模拟从陆架海尺度到冲浪带尺度过程的水动力模型和基于Higano et al .（1993）实验室实验的浮游幼虫模型。数值实验结果表明了海带垂直环流的重要性。由于海带垂直环流的作用，浮游生物幼虫被困在海带，无法从海带向近海流出。此外，对海岬防御工程影响的数值实验表明，海岬引起的近海水流可以使近岸地区的浮游生物幼虫流出。这说明海岬防御工事对蓝纹黄颡鱼浮游幼虫的分散和招募过程有很大的影响。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