Similarly, M. mevcenavia showed a 96-hr TLm between 32 and 33°C, 

 while the 96-hr TLm effluent dilution temperature was about 31.5°C. 



Experiments conducted with the gorgonian, Pterogorgia anoeps , were 

 unsatisfactory. The investigators were unable to establish satis- 

 factory criteria for colony death. Frequently gorgonian specimens 

 in higher effluent concentrations would withdraw their polyps and 

 remain in this retracted position. There was no way to determine 

 when the animals actually died until decomposition of the colony was 

 well advanced. The rate of decomposition was also influenced by the 

 concentration of the effluent. Dead gorgonian specimens placed in 

 dilutions of 5 to 10 percent effluent decomposed more rapidly than 

 those in 20 to 50 percent effluent dilutions. Some dead specimens 

 placed in 50 percent effluent did not show signs of decomposition 

 after 96 hours. 



Copper was the most deleterious constituent of the desalination plant 

 discharge as revealed by the laboratory bioassays. Copper probably 

 was responsible for most of the observed changes in the Safe Harbor 

 biota reported above. The small changes in temperature and salinity 

 (Fig. 12) produced by the effluent were well within normal seasonal 

 variations and within the tolerance limits of experimental animals 

 in the static bioassay tests. 



The amounts of copper discharged by the desalination plant frequently 

 increased copper concentrations at the stations to levels shown to 

 be toxic by acute bioassays. This was especially true during periods 

 when the plant was beginning operations following a shut-down. During 

 the acute bioassays, copper concentrations of only 250 ppb ionic 

 copper caused 50 percent echinoid mortality in 17 hours. Copper con- 

 centrations up to 359 ppb were recorded at the in situ bioassay stations 

 on days when the experimentally held animals died at those stations. 

 Copper concentrations as high as 538 ppb copper were found at biologi- 

 cal stations 3A and 3C associated with the turbid effusions following 

 start-ups of the desalination plant. 



COPPER TOXICITY 



Copper toxicity in the marine environment has been studied by numerous 

 workers. The literature has been recently reviewed by Raymont and 

 Shields (1964), Le Gros et at (1968), Zeitoun et al (1969B) , Lloyd 

 (1965). Additional studies include those of Portman (1968) and Hueck 

 et al (1968). 



Galtsoff (1943) reported nearshore copper values of 0.01 and 0.02 

 ppm and emphasized that levels of this magnitude were required for 

 physiological requirements of many marine invertebrates. Brooks and 

 Rumsby (1965) and Galtsoff (1964) and others have demonstrated copper 



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