Function Assessment that the Structure Incidentals to Seawall for Spontaneous Environmental Mitigation in the Innermost Region of Osaka Bay

Abstract

Amagasaki port, which is one of the most polluted sea areas, is located at the innermost region of Osaka Bay. The test structure was set as a vertical seawall for spontaneous environmental mitigation at our suggestion. We investigated the function of this structure for two years. As a result, the biomass of deposit feeder of the test structure is 5.3 times, that of the carnivore is 1.8 times, as many as the vertical structure at the bottom. Deposited bivalves and settling matter containing feces of bivalves ware caught on the shelf of the test structure. It was considered that organic matter was fed by deposit feeder and carnivore. These results show that this technology has some effects to decrease oxygen consumption by organic matter to improve the coastal environment on a continuous.