The Metal Mining Agency of Japan (MMAJ) conducted the eight year project "Environmental Impact Research for Manganese Nodule Mining 11 from 1989 to 1997 with an aim to evaluate the potential effects of the mining of manganese nodule and the preservation of the marine environment. Its purpose was to develop methods to evaluate environmental impacts expected to arise from commercial mining operations. Then MMAJ has initiated the next five year project "Environmental Impact Research on Marine Ecosystem for Deep-sea Mining" in 1998 to progress the results of the previous project by considering the impacts on marine ecosystem.
In Japan, the MMAJ has been entrusted by the Ministry of International Trade and Industry (MIT!) to undertake investigations on the effect of the manganese nodule mining in the marine environment. The project titled, "Environmental Impact Research for Manganese Nodule Mining" was an eight year study which began in 1989. It was undertaken in close collaboration with the National Oceanic and Atmospheric Administration (NOAA) of USA since 1990. The survey area was included in a Japanese mining claim in the equatorial part of the northeastern Pacific Ocean (Fig.1). The project surveys were focused on the surface and bottom layers in and near the area. In order to evaluate the impacts of the mining operations, an artificial benthic disturbance was carried out in the area in 1994. It is known as JET: Japan Deep-Sea Impact Experiment. Subsequent monitoring surveys were conducted in 1994, 1995 and 1996 after the disturbance. The purpose of these researches was to establish methods to assess the environmental impacts expected from the real mining. This paper reports the results of "Environmental Impact Research for Manganese Nodule Mining" and outline of "Environmental Impact Research on Marine Ecosystem for Deep-sea Mining".