Abstract
The values of dissolved oxygen, COD, Ignition Loss, Sulfide and Redox (Eh) in the Kasai artificial beach show almost same values as those of Banzu flats and Sanbanze, natural tidal flats in Chiba Prefecture.
However, the fluctuations in the biomass and species of the macrobenthos are so high that it cannot be considered a stable system. Those fluctuations are explained by factors such as the influx of river water. When the river water has been increased by rainfall, the water quality in Kasai artificial beach becomes a low salinity, and it was guessed that bivalves of Ruditapes phitippinarum, Mactra veneriformis, Mactra chinensis, etc. in the macrobenthos which are weak to the decrease of salinity, have been suffered big damage by low salinity.
