COMMUNITY STUDIES ON THE BIOLOGICAL PRODUCTION PROCESS OF MYSID INHABITING IN THE SURF ZONE OF SANDY COAST.

为了阐明桑迪碎波带在海岸生态系统中的功能作用，作者对仙台湾古糠虾（Archaeomysis kokuboi）的生物生产过程进行了调查，结果如下：1）仙台湾古糠虾在碎波带的桑迪滩中常年有大量的现存量。糠虾的丰度较高，尤其是在水深小于5 m的区域。2）滩坡糠虾高密度分布区随潮移动，与低潮线的距离恒定。糠虾主要栖息地的沉积物的中值粒径为2.0-2.3。在白天，大多数糠虾在表层打洞。（3）以卤虫为食的糠虾，在水温15 ℃，光照度0- 100 lux条件下，其日摄食率分别为：（1）100 - 100 lux，（2）100 - 100 lux，（3）100 - 100 lux，（4）100 - 100 lux，（5）100 - 100 lux，（5）100 -100 lux，（6）100 -100 lux，（7）100 -100 lux，（8）100 -100 lux，（10 -100 lux）100 - 100 lux，（10 - 100 lux）100 - 100 lux，（10 - 100 lux）100 - 100 lux，（4）食物对糠虾的转化率随生长而降低，幼虾为24.6-44.2%，成虾为8.9-13.8%。投饵后12 h，糠虾体内残留的物质量与摄食卤虫的物质量之比<14>为52%，投饵后24 h为38%。5）国保无囊对虾一生至少有2次以上产卵的可能性，其种群在一年中有6个以上的群体。在温暖季节的4 - 6月，骨骼生长迅速，成熟时体积较小，而在寒冷季节的11 - 1月，骨骼生长缓慢，在春季产卵，成为较大的成体。6）这些研究清楚地表明，A.kokuboi在桑迪碎波带生态系统中起着重要的作用，是维持海岸生物生产基本过程的关键物种。

In order to make clear the functional role of the sandy surf zone in a coastal ecosystem, the authors investigated the biological production process of a mysid Archaeomysis kokuboi in the Sendai bay.The summary of the results is shown below.1) In the Sendai bay, a misid A.kokuboi has a large standing crop in the sandy beaaches of surf zones all the year round. The abundance of the mysid is high especially in areas shallower than 5m in depth.2) High density distribution area of the mysid on the slope of beaches moves accompanying the tide and has a constant distance from the low tide lines. The median size of sediment of the main habitat for the mysid is 2.0-2.3. In the daytime most of the mysid are burrowing in the surface layr (0-3cm in depth) of the sand slope, and by night they are swimming in the water and feeding mainly on flagellates and copepods.3) Daily feeding rates of the mysid fed with brine shrimps for food, under the conditions of 15ﾟC in water temperature and 0-100 lux in illuminance, are 24.8% in wet weight and 39.7% in dry weight.4) Conversion rates of the food ingested to the mysid decrease with the growth ; from 24.6-44.2% in young stage to 8.9-13.8% in adult. The ratios of the amount of substance remained in the body of mysid and that ingested brine shrimp labeled with ^<14>C are 52% for 12 hours and 38% for 24 hours after feeding.5) A.kokuboi has a possibility of spawning at least more than two times throughout the life, and for the population it is recognized that they have more than 6 cohorts in one year. Cohorts bone during the warm season April-June grow fast to mature in a small size, and that bone during the cold season November-January grow slowly and spawn their eggs in spring as the larger sized adult.6) These studies clearly show that A.kokuboi plays an important role as a key species in the sandy surf zone ecosystem sustaining the basic processes in a coastal biological production.