抄録
Field investigations and indoor experiments were performed to evaluate the environmental function of the oyster reef existing around the Nekozane River mouth in Sanbanze Shallows of Tokyo Bay in terms of the decomposition rate of organic matter. The number of living oysters and oystershells was counted to estimate their densities in the reef. Sediment samples were collected and analyzed to understand spatial variation in sediment properties around the reef. Indoor experiments were conducted to determine the oxygen consumption rates of oysters and oystershells in terms of water temperature. All of the information are integrated on GIS and the spatial variation in decomposition rate of organic matter inside and outside of the oyster reef. Very high organic matter decomposition rate of the oyster reef was obtained during summer, which is comparable to several times of that of sandy bed in Sanbanze Shallows. According to the historical aerial photos, the oyster reef remains for more than 10 years. These results show that the oyster reef has valuable and sustainable function of water purification.
