The SHL toxicity tests on copepod mortality, are inexact because they 

 did not include the dilution effect of turbulence which occurs readily 

 in the ocean, but is difficult to simulate in the laboratory. Redfield 

 and Walford C1951) show, that the pH of water from the wake of an acid- 

 dumping barge was above 6.0 in all samples collected more than 3 minutes 

 after passage of the vessel; a pH of 7 was reached about 3.5 minutes 

 after duinping, and that acid disposal was not an important factor in 

 copepod mortality. They reported that the zooplankton exposed to samples 

 of water from the wake of the disposal vessels were immobilized, but re- 

 covered in a few minutes, except for a sample taken at 145 yards behind 

 the barge only 42 seconds after discharge. Even these zooplankton re- 

 covered when the wake water was diluted with an equal volume of non- 

 contaminated sea water. The SHL data (Table 18) showed no copepod mor- 

 tality in 2 minutes at pH 5.9-6.0 and no mortality in 60 minutes at pH 

 values of 6.1-6.5. The dilution of the acid waste in the Redfield and 

 Walford work shows that the organisms are not exposed to the high con- 

 centrations used by SHL in its laboratory tests. The SHL data, therefore, 

 do not support complete mortality, and no such mortality was detected in 

 the Bight. 



The vertical migration of copepods is controlled by light intensity 

 (Herman, 1963; Segal, 1970). Copepods are found in deeper waters during 

 daylight and near the surface at night. On the basis of this, SHL con- 

 cluded that the ferric hydroxide floe resulting from acid dumping, al- 

 though not directly toxic to copepods, produces turbidity that changes 

 light conditions and affects the vertical distribution pattern of cope- 

 pods. While this conclusion may be true, changes in vertical distribu- 

 tion of copepods may not be an adverse effect, and increased turbidity 

 may not inhibit the abundance of these organisms. Reduced light in- 

 tensity due to overcast skies could have the same effect. The ferric 

 hydroxide floe either settles out or is dispersed rapidly. Refield and 

 Walford (1951) reported the maximum time they observed a recognizable 

 turbidity stain to be 8 hours. The ferric hydroxide floe is not toxic 

 to copepods. In the laboratory, copepods held in water containing up 

 to 500 times the concentration of ferric hydroxide found in the Bight 

 survived several days. under starvation conditions. 



Similar laboratory experiments by SHL showed that copepods can live 

 in sludge-contaminated water for over 24 hours under confined conditions. 

 Death of some copepods in the experiments over extended periods of time 

 probably resulted from a decrease in dissolved oxygen caused by the bio- 

 chemical oxygen demand of the sludge. 



An aerated control in future experiments of this type would show 

 whether there were any effects from sludge other than its oxygen demand 

 (SAC, 1972). 



d. Effects of Ocean Dumping en Phytoplankton . No extensive phyto- 

 plankton studies in the dumping grounds of the New York Bight have been 

 conducted. Inhibition in the growth of phytoplankton in lab cultures of 

 water from the sludge dump has been reported by Barber and Krieger (1970) . 



135 



