CONTENTS 



Page 



Introduction 215 



Similar Effects in Shallow and Deep Water 222 



Surface Effects 222 



Water Column Effects 222 



Benthic Impacts 223 



Alteration of Wave Patterns 224 



Seasonal 224 



Different Effects in Shallow and Deep Water 226 



Surface Effects 226 



Water Column Effects 226 



Benthic Effects 226 



Shallow Water Mining Experience 227 



Deep Water Mining Studies 236 



DOMES: The Deep Ocean Mining Environmental Study 236 



FoUow-Up to DOMES 239 



Environmental Effects From Mining Cobalt Crusts 240 



Gorda Ridge Task Force Efforts 244 



Boxes 



Box Pa.ge 



6-A. ICES — International Council for Exploration of the Sea 228 



6-B. U.S. Army Corps of Engineers 229 



6-C. Project NOMES 230 



6-D. New York Sea Grant Studies 231 



6-E. EPA/COE Criteria for Dredged and Fill Material 232 



6-F. Deep Ocean Mining Environmental Study (DOMES) 237 



6-G. Cobalt Crust Case Study 243 



6-H. Gorda Ridge Study Results 245 



Figures 



Figure No. Pa-ge 



6-1 . The Vertical Distribution of Life in the Sea 216 



6-2. Impacts of Offshore Mining on the Marine Environment 217 



6-3. Spawning Areas for Selected Benthic Invertebrates and Demersal Fishes 220 



6-4. Composite of Areas of Abundance for Selected Invertebrates Superimposed 



With Known Areas of High Mineral Potential 221 



6-5. The Effect of Discharge Angle and Water Current on the Shape and Depth 



of Redeposited Sediments 235 



6-6. Silt Curtain 236 



Tables 



Table No. Page 



6-1. Environmental Perturbations from Various Mining Systems 234 



6-2. Summary of Environmental Concerns and Potential Significant Impacts of 



Deep-Sea Mining 238 



