Marine Environmental Change Induced by Anthropogenic Activities – From a Viewpoint of Aquatic Palynomorph Assemblages Preserved in Sediment Cores of Beppu Bay, West Japan

Stratigraphic cluster analysis using aquatic palynomorphs preserved in the core sediments revealed a rapid eutrophication due to anthropogenic activities from mid 1960s Beppu Bay, East Kyushu, Japan. These assemblages were divided into three major units: BP-I, BP-II and BP-III, also only dinoflagellate cyst following four units Bay: BP-A, BP-B, BP-C, BP-D. Unit boundaries based on cysts different except upper part, BP-III BP-D, both of which clearly indicated sea water bottom sediments. On other hand, assemblages, BP-A was characterized by stable occurrence Spiniferites bulloideus hyperacanthus, Lingulodinium machaerophorum Gonyaulacales, reduction heterotrophic Peridinioid Brigantedinium spp. In BP-C there clear decrease L. machaerophorum. BP-B decreases S. , hyperacanthus little increase Spniferites bentori. an Echinidinium BP-D subdivided Subunit BP-D1 where showed marked accompanied appearance Tuberculodinium vancampoae PB-D2 total cysts. From marine environment period suggested be warm stable. However, started BP-B. The suggest that became cooler than BP-A. Significant increases bulloideus, hypearcanthus, machaerophorum, T. vancampoae, spp., Polykrikos kofoidii characteristic density ratio are manifestations Oslo fjord Signal Heterotroph Signal, respectively. addition, microforaminiferal lining continued might indicate deterioration sediment environment.