site were removed or destroyed during dredging. Eight months after dredging, 

 biomass at seven of the effected stations was 28 percent lower than at "control" 

 stations. Species diversity was not significantly different at effected and 

 uneffected locations. Channel dredging has had no long-term influence on 

 vertebrate wildlife populations in D'Olive Bay. 



188. WAKEMAN, T.H., "The Biological Ramifications of Dredging and Disposal 

 Activities," Dredging: Environmental Effects and Technology," Proceed- 

 ings of the World Dredging Conference, July 1976, pp. 55-68. 



This discussion concerns the environmental ramifications of dredging and 

 disposal activities in San Francisco Bay. The investigation examined the impact 

 that operations generated on water quality, sediment heavy metal release, and 

 benthic and pelagic organisms, both in terms of physical and chemical effects. 

 In the upper water column neither dredging nor disposal operations cause sig- 

 nificant changes in water quality. Plumes were observed, but these were gen- 

 erally of short duration and seldom contained high suspended-solid concentra- 

 tions. The physical impact of various particle concentrations with changes in 

 temperature and dissolved oxygen was investigated using several San Francisco 

 Bay benthic and pelagic species. In general, the results showed that the levels 

 observed in the field would not cause adverse effects on adult benthic species 

 at saturated oxygen and winter temperatures (10° Celsius) . Effects were more 

 pronounced at higher temperatures and lower dissolved oxygen concentrations. 

 Pelagic species could be negatively impacted by the solids concentrations 

 found at disposal sites with increasing effects as temperature and dissolved 

 oxygen conditions became more adverse. Investigations of desorption phenomena 

 showed that cadmium, lead, zinc, and copper can be emitted from resuspended San 

 Francisco Bay sediments under oxygen-rich conditions. Biological investigations 

 showed that dissolved heavy metals ions can be accumulated during low salinity 

 periods and desorbed as the salinity increases. Heavy metals may be absorbed 

 and accumulated by organisms following dredging and disposal activities via 

 chemical reactions in the water column causing increased ambient concentrations 

 or by ingesting and breaking down organic matter containing metals. 



189. WAKEMAN, T.H., and FONG, C.C, "Biological Impacts of Dredge Material 

 Disposal in the San Francisco Bay," Proceedings of the Seventh Annval 

 Offshore Technology Conference, May 1975, pp. 93-102. 



Studies were conducted to determine the effects of dredging and disposal 

 operations on the main ship channel across the San Francisco Bay. Disturbance 

 of a basically sandy substrate causes little ecological disruption of the 

 marine benthos. Organisms associated with such an environment have evolved 

 with an unstable substrate and are able to survive disturbances. 



190. WATER AND AIR RESEARCH, INC., "A Study on the Effects of Maintenance 

 Dredging on Selected Ecological Parameters in Gulf port Harbor, Missis- 

 sippi, " Gainesville, Fla., July 1975. 



This report assesses the environmental effects of maintenance dredging 

 in Mississippi Sound in 1974. Background conditions were measured before and 

 after dredging, and extensive monitoring was conducted during the dredging 

 operation. It was found that dredging had no significant or lasting effect 

 on any of the conditions evaluated in this investigation. Turbidities and 

 suspended solids were measured and the size and dispersion of the discharge 



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