Ch. 6— Environmental Considerations • 227 



Photo credit: Paul Rodhouse, British Antarctic Survey 



Mussels, like many benthic marine organisms, filter 

 their food. Sediments discharged from dredging 

 vessels or stirred up by mining activities may clog 

 feeding and respiratory surfaces of these animals or 

 completely bury populations. 



cies.'° 31 Animal populations in fine-grained sedi- 

 ments appear to recover more rapidly than those in 

 coarse-grained sediments, which may require up to 

 3 years for recovery. ^^ Recolonization rates in the 

 deep sea are not known with any certainty, but they 

 appear to be long — on the order of years — in areas 

 not subject to periodic disturbance. ^^"^^ Deep-sea 

 benthic communities are areas of high species diver- 

 sity, few individuals, slow recolonization rates, and 

 questionable resilience. Shallow water benthic com- 

 munities may have either high or low diversity, usu- 

 ally with large numbers of individuals, fast recoloni- 

 zation, and resilience to physical disturbance. 



'"R.T. Saucier et al. , Executive Overview and Detailed Summary, 

 Technical Report prepared for U.S. Army Corps of Engineers Of- 

 fice, Chief of Engineers, Washington, D.C., December 1978. 



^'D. Thistle, "Natural Physical Disturbances and Communities of 

 Marine Soft Bottoms," Marine Ecology Program Service, No. 6 

 (1981), pp. 223-228. 



'^Saucier et al., p. 75. 



^^F.N. Spiess et al., Environmental Effects of Deep Sea Dredging, 

 Report to National Oceanic and Atmospheric Administration, No- 

 vember 1986. 



'*C. R. Smith, "Food for the Deep Sea: Utilization, Dispersal, and 

 Flux of Nekton Falls at the Santa Catalina Basin Floor," Deep-Sea 

 Research, vol. 32, No. 4. 



"J.F. Grassle, "Slow Recolonization of Deep-Sea Sediment," Na- 

 ture, No. 265 (1977), pp. 618-619. 



"J.F. Grassle, "Diversity and Population Dynamics of Benthic 

 Organisms," Oceanus, No. 21 (1978), pp. 42-45. 



SHALLOW WATER MINING EXPERIENCE 



Since little mining has taken place offshore of the 

 United States^ ^, any discussion of the environ- 

 mental impacts must rely heavily on the European 

 experience. This experience is summarized in the 

 documents of the International Council for the Ex- 

 ploration of the Seas (ICES — see box 6- A). Addi- 

 tionally, the very extensive experience of U.S. 

 Army Corps of Engineers in lifting, redepositing, 



^^ There is currendy sand and gravel mining in the Ambrose Chan- 

 nel of New York Harbor and a gold mining operation off Nome, 

 Alaska, (see Ch. 5). 



and monitoring sediments from dredging opera- 

 tions provides insights into the effects of shallow 

 water mining. In particular, the 5-year Dredged 

 Material Research Program (DMRP) (see box 6- 

 B) attempted to cover all types of environmental 

 settings offshore. The information gathered is rele- 

 vant to the activities involved in mining sand and 

 gravel or placer deposits. Finally, there are two 

 regional efforts — The New England Offshore Min- 

 ing Environmental Study (NOMES) (see box 6- 

 C), and Sea Grant studies in New York Harbor 



