222 • Marine Minerals: Exploring Our New Ocean Frontier 



SIMILAR EFFECTS IN SHALLOW AND DEEP WATER 



Surface Effects 



The surface plume created by the rejection or 

 loss of some of the mined material or the disposal 

 of unused material could cause a number of effects 

 on the phytoplankton (minute plant life) commu- 

 nity Euid on primary production.^ In the short term, 

 reduction of available light in and beneath the 

 plume may decrease photosynthesis. Nutrients 

 originally contained in the bottom sediments but 

 introduced to the surface waters may stimulate 

 phytoplankton productivity. Long-term plume ef- 

 fects from long-term continual mining operations 



*A.T. Chan and G.C. Anderson, "Environmental Investigation 

 of the Effects of Deep-Sea Mining on Marine Phytoplankton and Pri- 

 mary Productivity in the Tropical Eastern North Pacific Ocean," Ma- 

 rine Mining, vol 3. (1981), No. 1/2, pp. 121-150. 



might lead to changes in productivity or changes 

 in species composition. 



Water Column Effects 



High particulate concentrations in the water 

 column can adversely affect the physiology of both 

 swimming and stationary animals,^ altering their 

 growth rate and reproductive success. Such stresses 

 may lead to a decrease in the number of species,' 

 a decrease in biomass (weight/unit area), and/or 



^D.C. Rhoads, and D.K. Young, "The Influence on Sediment Sta- 

 bility and Community Trophic Structure, "yournay of Marine Re- 

 search, No. 28 (1970), pp. 150-178. 



'R.W. Grigg and R.S. Kiwala, "Some Ecological Effects of Dis- 

 charged Wastes on Marine Life," California Fish and Game, No. 

 56 (1970), pp. 145-155. 



Photo credit: U.S. Geological Survey 



A surface plume of turbidity is produced when a dredge discharges material overboard. The extent, duration, and negative 



impacts of such a plume depend on the size and composition of the rejected material. Larger particles m\\ settle out 



quickly and the plume m\\ rapidly disperse. Very fine sediments may remain suspended for several days. 



