MULTIPLE-FACTOR AND SYNERGISTIC STRESSES 



735 



survival times. The megalops were more tolerant of cadmium than 

 were the zoeal stages. Christiansen and Costlow (1975) reported on 

 the effects of salinity and cyclic temperature on R. hanisii. 

 Christiansen, Costlow, and Monroe (1977), recently studied the 

 effects of the juvenile hormone mimic ZR-515 (Altosid), salinity, 



u 



10 



15 



20 



25 



SALINITY %o 



30 



35 



40 



Fig. 5 Effects of incubation salinity and temperature on viability of 

 developing eggs of Parophrys vetulus. Various gross developmental 

 anomalies occurred more frequently in certain areas of the salinity — 

 temperature test space, as indicated. (After Alderdice and Forrester, 

 1968.) 



and cyclic temperatures on this same species. No significant 

 synergism between Altosid, salinity, and temperature was reported. 

 The amphipod Corophium triaenonyx inhabits parchment tubes in 

 fouling communities on wood and concrete jetties. The eggs are more 

 sensitive to salinity than are adults. The optimum range for 

 development is between 27.5 and 30 %o and a constant temperature 

 of 28°C (Shyamasundari, 1976). 



Insects inhabiting freshwater ponds are shown to be affected by 

 experimental photoperiods and temperatures. Larvae of the odonate 

 species Plathemis lydia demonstrated stimulated growth rates when 

 subjected to longer photoperiods or higher temperatures. However, 

 the magnitude of these effects varied with the season of the year 



