Establishment of stratigraphical and paleontological methods to understand the dynamics of coastal ecosystem and the abnormal sea-level changes occurred in the 20^<th>.

我们进行了几项基础研究，以估计沿海海洋生物对与全球变暖有关的海平面上升的反应。今年我们特别强调以下几点：从封闭的沿海泻湖中采集柱状沉积物样品并进行沉积物分析;开发过去测年的测量技术;作为了解长期气候变化以及沿海环境变化的工具的现场咸水生物实验研究。年代学研究组推动了锆石U-Pb法、石英ESR法和方解石TL法的广泛应用。分析了海藻中^<228>Ra/^<226>Ra比值的季节变化和海水样品中极低的^ Cs本底测量值<137>。生物组研究结果表明，初夏微咸水温度极低时，贝壳生长迅速。蚬壳的生长随微咸水由高盐度向低盐度的变化而加快。在BBM琼脂平板上对新丁湖20℃培养的浮游植物进行了分离。环境研究小组研究了来自新知湖（岛根）、濑间湖（北海道）、大村湾（长崎）和松川浦（福岛）的柱状沉积物的粒度、有机物质和有机残留物。1680年，当比伊川川流入新寺湖时，海水密度流的证据被确认。重建的介形虫组合揭示了20世纪60年代大村湾低氧环境的出现，这与低氧水出现的观测证据是同期的。结果表明，不同地区的海岸带生物对海平面变化的响应不同。

We carried out several basic studies in order to estimate the response of coastal marine organisms to the sea-level rise in association with a global warming. We particularly stress the following points in this year : sampling of columnar sediments from enclosed coastal lagoons and the sediment analyses ; development of measuring technique for past dating ; experimental studies of in situ brackish organisms as a tool to understand a long-term climatic variation as well as coastal environmental changes. Geochronological study group has promoted wide applications of U-Pb method for zircon, ESR method for quartz and TL method for calcite. Seasonal variation of ^<228>Ra/^<226>Ra ratio in sea-weed and extremely low background measurements of ^<137>Cs in seawater samples were analyzed. Biological group get the results that early summer growth of the shell is rapid when the brackish water temperature is extremely cold. The shell growth of Corbicula increased when the brackish water changed from high salinity to low one. Isolation of culture strains of phytoplankton at 20℃ form brackish lake Shinjiko was performed on BBM agar plates. Environment study group examined the columnar sediments from Lake Shinjiko (Shimane), Lake Saroma (Hokkaido), Ohmura-Bay (Nagasaki) and Matsukawa-ura (Fukushima) for their grain-size, organic materials and organic remains. Evidence of density flow of marine water was recognized when the Hii-gawa River flowed down into Lake Shinji in 1680. The reconstructed ostracode assemblage revealed the appearance of hypoxia environment in the 1960s in Ohmura Bay, which is coeval with the observed evidence of low-oxygen water appearance. We found a different response of coastal organisms to sea-level variations according to the different areas.