Environmental Indicators Based on Freshwater Diatom Assemblages and Its Application to Reconstruction of Paleo-environments

The purpose of this paper is to establish the environmental indicators for reconstruction of freshwater paleoenvironments. Living diatom materials were collected from rivers, lakes, marshes, high moors and lands. Therefore, diatom species were classified on the basis of habitats, as follows.1. Indicator species of the upper stream of a river (J)2. Indicator species of the middle-lower part of a river (K)3. Indicator species of the most lower part of a river (L)4. Indicator species of a lake (M)5. Indicator species of a lake and a marsh (N)6. Indicator species of a marsh (O)7. Indicator species of a high moor (P)8. Indicator species of a land (Q)Using those diatom indicator species, the marine regression process and the paleoenvironments of upper alluvial deposits in Yanasegawa valley plain were examined. As a result, those diatom indicator species are very useful for reconstruction of freshwater paleoenvironments.