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：从封闭的沿海泻湖取样柱状沉积物和沉积物分析；过去年代测定技术的发展对原位微咸生物进行实验研究，作为了解长期气候变化和沿海环境变化的工具。年代学研究小组推动了锆石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，以及海水样品中^<137>Cs的极低本底测量值。生物学组的研究结果表明，咸淡水温度极低时，初夏贝壳生长迅速。当咸淡水由高盐度变为低盐度时，小球藻的壳生长加快。在BBM琼脂平板上对新枝湖20℃下的浮游植物培养菌株进行了分离。环境研究组对岛根县新枝湖、北海道沙罗玛湖、长崎大村湾和福岛松川村的柱状沉积物的粒度、有机物质和有机残留物进行了检测。1680年，Hii-gawa河流入真嗣湖时，人们发现了海水密集流动的证据。重建的介形虫组合揭示了60年代大村湾缺氧环境的出现，这与观测到的低氧水体出现的证据是一致的。我们发现，不同地区的沿海生物对海平面变化的反应不同。

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.