Deep-Sea mineral resources are expected to support the activity of our future industries. At the same time however, biological communities in the same region are thought to be a valuable resource for our future generations. Therefore it is necessary to consider not only the mining development but also ways of protecting and conserving the abyssal communities and organisms that are characterized by their specialized niches, fragility and rare abundance. In 1991, at the request of the Ministry of International Trade and Industry (MITI), the Metal Mining Agency of Japan (MMAJ) started the project entitled "Environmental Research for Manganese Nodule Development", and in 1994 as a part of this research, an environmental impact experiment named "Japan Deep-Sea Impact Experiment = JET" was initiated to evaluate the effects of· sediment resuspension and redeposition resulting from deep-sea mining. This experiment consisted of three phases, namely a pre-disturbance survey, an artificial disturbance and a post-disturbance survey. In the pre and post- disturbance surveys, sediment samples were collected using a Multiple Corer(MC). The artificial disturbance was created by a benthic disturber that was designed to dredge sediment and discharge it as a slurry at a height of about 5m above the seafloor. In addition, throughout the experiment period, deep sea currents and sedimentation rates were observed by several mooring systems. As a result, 19 benthic disturber tow transects were conducted in the survey area and 9,200,000 liters of slurry or 352 tons of sediment (dry weight) was discharged and resuspended. 27 sediment samples were collected and analyzed to compare the pre- and post-disturbance conditions. From the preliminary results, some disturbance effects were recognized from environmental and biological parameters, deep sea photographs and sediment trap data.
Deep-sea mineral resources are expected to support the activity of our future industries.