The Characteristics of Deep-Sea Epifaunal Megabenthos Community Two Years After an Artificial Rapid Deposition Event

Abstract

The Japan Deep-Sea Impact Experiment (JET) was carried out in the summer of 1994, at the central Pacific Ocean, to test the effects of rapid artificial deposition, supposed to occur during future commercial mining. As a part of this experiment, the abundance of megabenthos was compared between areas where sediment plume arrived two years ago (DA) and a control area not disturbed (NDA), using the finder-installed deep-sea video camera system (FDC). The densities of total megabenthos, motile species and deposit feeders were significantly lower in DA than in NDA. Within dominant taxonomic groups, holothurians, which were typical deposit feeders, were significantly less in DA than in NDA. On the other hand, the densities of sponges and ophiuroids were not different between the two areas. The observed difference suggests that the deposit feeders were sensitive whereas suspension feeders and omnivores were resistant to the artificial disturbance. The tendency can be explained if one notice that the food environment for deposit feeders remained disturbed for a long time, but that for suspension feeders and omnivores were restricted during the period of the experiment