Abstract
Water environmental condition of inflow rivers of Yatsu tidal flat was conducted using biotic indicatiors such as diatom (primary producer) and mactobenthos (final consumer). By diatoms, the rivers were assessed as α-os~β-ms from the viewpoint of DAIpo and RPId. The diatoms observed indicated seasonal succession, and the dominant species were Nitzschia, Navicula, Cymbella, Frustulia, Amphipleura, Gyrosigma and Amphora. By macrobenthos, they were assessed as substantially under good condition with the exception of summer season. The macrobenthos also indicated seasonal succession, and the domoinant species were Grandidierella japonica, Hydroides elegans, Lycastopsis augeneri, Ruditapes philippinarum, Amphitoe valida, Petricolla sp. and Batillaria cuminagi.
