658 



CHUNG AND STRAWN 



*Exposure was for 30 min above and 150 min below the cooling towers; 54 

 species were tested at various constant temperatures. 



fThe dash (— ) indicates no observation at discharge-canal temperature; 100% 

 survival is assumed. 



jThe abbreviation NLT is normal lifetime. 



minnow, Cyprinodon variegatus (95%); Gulf killifish, Fundulus 

 grandis (96%); mosquitofish, Gambusia affinis (62%); sailfin mollie, 

 Poecilia latipinna (92%); rough silversides, Membras martinica (1%); 

 Atlantic spadefish, Chaetodipterus faber (3%); leatherjacket, 

 Oligoplites saurus (3%); mojarra, Eucinostomus sp. (10%); striped 

 mullet, Mugil cephalus (44%); white mullet, M. curema (39%); 

 sharptail goby, Gobionellus hastatus (3%); and naked goby, 

 Gobiosoma bosci (3%). Death rates were zero for all organisms tested 

 during the cool season at 32°C [except the bay anchovy (0.0007)] 

 and during the cold season at 27° C. This indicates that aquatic 

 animals inhabiting the discharge canal and entering from intake water 

 should have little problem with the heated effluent from October to 

 May. Predicted survival probabilities, in terms of average tempera- 

 tures, were 100% for all animals except bay anchovy (88%. in the 

 cool season) from October to May after a 180-min passage through 

 the discharge-canal system (Table 1). 



Survival probabilities in the discharge-canal system may be 

 overestimated. The bay anchovy, and probably other least-resistant 

 fishes, died at peak cold-season effluent temperatures. Such non- 

 thermal factors as impingement and mechanical injury from the 

 intake screens and the impact of cascading water in the cooling 

 towers and the thermal factor of cumulative heat dosage were not 

 considered. 



Adequacy of the Stochastic Death Model 



The model used was previously untried for predicting survival of 

 animal populations passing through the power-plant discharge 

 system. It is based on the model described by Pielou (1969). 



