Although plankton appear to better withstand passage through 

 cooling systems, mortalities of entrained zooplankton have been re- 

 ported to vary from 15 to 100 percent, depending on the size of the 

 organisms [134]. It is important to protect plankton because they 

 supply basic nourishment for the whole chain of life in the estuary 

 and because the young, larvae, and juvenile stages, of valuable finfish 

 and of shellfish are part of the plankton (Figure 43). 



Figure 43. Potential power plant impacts on striped bass and 

 associated food items (Source: Reference 136). 



ORGANISMS NOT ENTRAINED BUT DEPENDENT ON SUSCEPTIBLE ORGANISMS 



STRtPEDBASSPHEY 



ANCHOVIES 



AND 

 YOUNG OF 

 ALEWIFES 

 MENHADEN 

 WHITE PERCH 

 CROAKER 

 SPOT 



Solutions to the problem of entrainment are (1 

 areas when locating the intake structures, and (2) 

 ume of cooling water by using closed-cycle systems, 

 cooling system may be costlier than a once-through 

 favors long-term environmental protection. Advance 

 produced satisfactory closed-cycle cooling systems 

 two to four percent as much water as is used by ful 

 consequently, the closed-cycle alternatives consume 

 the marine biota consumed by once-through plants 

 that they also discharge a similarly small fraction 

 lie waters. Closed-cycle systems may have natural 



) avoidance of vital 

 reduction of the vol- 



A closed-cycle 

 system but it greatly 

 d engineering has 

 that utilize only 

 ly open-cycle systems; 

 only 1/25 to 1/50 of 

 Another advantage is 

 of heat into pub- 

 draft cooling 



169 



