The effect of artificial resedimentation on the deep-sea meiofauna community was studied in the Japan Deep-Sea Impact Experiment (JET) during 1994. In two cruises before and after the resedimentation experiment (JETl and JET2), pre- and post-impact samples were taken respectively using a multiple corer. The analysis of meiofauna has been partially completed. In these preliminary results, the abundance of metazoan meiofauna of JET2 samples was significantly lower than that of JETl. This significant difference was also shown in the abundance of nematoda. Abundance of copepoda and bacteria distributed in the upper sediment displayed lower values in JET2.
In the past 30 years, most studies of deep-sea meiobenthos have reported their abundance in relation to water depth. There have been three such studies reported for the Pacific (Thiel, 1975; Sinder et aI., 1984; Shirayama, 1984). However, in recent years, studies to understand the relationship between artificial impacts and the biological reactions have been conducted in the Pacific Ocean. Now, three environmental projects focusing on the biological reaction caused by artificial resedimentation are currently being conducted by the USA (BIE project), Germany (DISCOL project) and Japan (JET project) in the eastern Pacific Ocean. The JET project was implemented by the Japanese government, through the Metal Mining Agency of Japan, in order to evaluate possible future mining impacts. After three years of baseline studies since" 1991, the JET (Japan DeepSea Impact Experiment) was carried out in August/September 1994. The JET cruise consisted of two legs. The purpose of the first leg, named "JET1" was to confirm the pre-impact condition of the meiobenthic communities and the environmental factors before the disturber towing. The first was to disturb the deep sea floor and to create artificial resedimentation using the disturber, and the second was to observe the biological reactions to the rapid resedimentation.
