Sediment redistribution during simulated benthic disturbance and its implications on deep seabed mining

A benthic disturbance experiment was conducted in the Central Indian Basin to evaluate the possible effects of sediment redistribution on marine ecosy stem during deep-sea mining. The analyses of disturbance features on the se afloor and particle resettlement indicate that the most intense impact is c reated within the experiment site, and some of the resuspended sediments th at remain in the near-bottom water after the disturbance are transported aw ay from the site, changing the physico-chemical conditions in the area. Res edimentation is observed on either side of the disturbance zone, with an in crease in suspended particles by 300% (from 49 to 150 mg/m(2)/day) during t he disturbance and a reduction by 33% (to 95 mg/m(2)/day) immediately after the experiment. Higher collection of particles as well as an increase in o rganic carbon in seafloor sediments S-SW of the disturbance zone indicates directional migration of suspended material and redeposition in the adjacen t areas. The implications of increase in turbidity and sedimentation rates in the near bottom water column due to sediment re-suspension, as well as l ateral migration of sediment, on the benthic ecosystem have been discussed. These parameters provide important inputs in ascertaining longterm effects of deep-sea mining. (C) 2001 Elsevier Science Ltd. All rights reserved.