564 FORD, FOREMAN, GRUBBS, KROLL, AND WATTS 



increased under both treatment conditions. Results of analyses of 

 covariance and multiple range tests indicated that growth in weight 

 of the two larger size groups was significantly greater in both effluent 

 regimes than in Scripps and generating-station controls (P < 0.05). 

 Roperia poulsoni of all three size categories exhibited only slight 

 changes in weight and W/L ratios both in the control and effluent 

 regimes. Results of analyses of covariance indicated that growth in 

 weight for all size groups was not significantly different among the 

 control and effluent-treatment conditions (P > 0.05). 



In contrast, all size groups of ^. iindosa exposed to both effluent 

 conditions showed evident decreases in both weight and VV/L ratios 

 (Table 5). Results of analyses of covariance and multiple range tests 

 indicated that growth in weight for the two smaller size groups' of 

 this species was significantly lower in both simulated effluent regimes 

 than in the two controls (P < 0.05). 



Chemical Conditions 



Analyses were conducted simultaneously to evaluate major 

 chemical constituents of the laboratory water sources which might 

 be affected by operation of the generating station. The trace metals 

 Cu, Zn, Cd, Pb, Co, Cr, and As were found to be present in very low 

 concentrations, and there were no significant differences in concen- 

 trations in the control and thermal-effluent water supplies used at 

 the Scripps aiid generating-station laboratories (Ford et al., 1976; 

 Dorband et al., 1977). Monitoring data for the period from July to 

 November 1975, obtained from generating-station records, were used 

 to compare levels of oil and grease and chlorine in control and 

 thermal-effluent water supplies at the generating-station laboratory. 

 Results of a t-test comparing sample means indicated no significant 

 difference (P > 0.05) in concentrations of oil and grease between the 

 intake water supplied to the controls (x = 0.79 mg/liter) and the 

 thermal effluent (x = 0.72 mg/liter). Concentrations of total residual 

 chlorine in both intake and effluent water supplies at the points 

 where they entered the laboratory were below the detection limit for 

 the amperometric method of analysis used (< 0.01 mg/liter) during 

 and after release of chlorine into the cooling-water system. 



Weekly analyses indicated that dissolved oxygen concentrations 

 were maintained near air-saturation levels uniformly in all control 

 and treatment tanks. This was accomplished by using air stones and a 

 high flow rate of seawater. Salinity and pH also remained very 

 constant and were unifonn among the control and effluent tanks. 



These results indicate that there were no evident differences in 

 any of the chemical constituents among the control and effluent 



