The mega-infaunal community of an artificial tidal flat in Mikawa Bay was investigated for two years in order to evaluate its biological production and water purification function. A total of 47 species were identified, which was comparable to natural tidal flat in Mikawa Bay. The dominant species were the bivalves, such as Mactra chinensis, Ruditapes philippinarum and the crustaceans, Portunus trituberculatus. During the first six months of the research period, the abundant biomass of bivalves at the artificial tidal flat resulted in higher removal rate of particulate organic nitrogen, which fell within the range of a natural tidal flat in Mikawa Bay. However, the biomass of bivalves drastically decreased in accordance with the appearance of diving ducks and mass fishery. This study suggests that the biomass of mega-infaunal community in artificial tidal flats may drastically decrease by predation or fishery if the areas of created tidal flats are small.
