RESULTS 



Effect of MONO-585 on Development 



Survival of the zoea ofR. harrisii was unaffected by the presence of 1 .0 and 

 0.1 ppm MONO-585 when the larvae were maintained in salinities of 20 and 35 

 ppt (Figure 21-1). In the reduced salinity of 5 ppt, however, total mortality 

 within the zoeal stages was observed with a dilution of 1 .0 ppm, while survival 

 at 0.1 ppm was higlier than that observed for either the seawater control or the 

 acetone control (Figure 21-1). A concentration of 10 ppm MONO-585 was 

 lethal in all three experimental salinities and none of the zoeae developed 

 beyond the first stage. 



Megalopa of R. harrisii v^ere affected by the presence of 1.0 ppm 

 MONO-585 when combined with a high salinity of 35 ppt but survival of this 

 last larval stage was only shghtly reduced at 20 ppt (Figure 21-1). There were 

 no reductions in survival of megalopa in 0.1 ppm, regardless of the salinity. 



In those experimental sahnities in which some development occurred, the 

 time required for development from hatching to the megalopa, megalopa to the 

 crab, and hatching to the time of final metamorphosis to the crab, was 

 unchanged by the presence of either 1.0 or 0.1 ppm MONO-585 (Figure 21-2). 

 The development pattern followed the sequence of four zoeae and one 

 megalopa normally observed for R. harrisii and no additional or supernumerary 

 larvae were noted. 



As indicated in Figure 21-3, total mortality of megalopa of C sapidus was 

 observed in all series maintained at 5 ppt, including the control. In salinities of 

 20 ppt and 35 ppt, 10 ppm MONO-585 resulted in total mortality. One ppm 

 reduced survival from 100 percent observed in the controls to 40 percent, 

 regardless of salinity, and 0.1 ppm reduced survival to approximately 90 

 percent. Time for metamorphosis of the megalopa, from the final zoeal molt to 

 the appearance of the first juvenile crab, varied from a mean of approximately 

 8 days to 1 1 days, but the presence of MONO-585 did not appear to be related 

 to this variability (Figure 21-4). 



When cultured in 5°C, 24 hour cyclic temperature (20-25'^; 25-30°; and 

 30-35*^; Costlow and Bookhout, 1971) there was no significant change in 

 survival of control series or those series of megalopa maintained at 0.1 ppm 

 MONO-585 (Figure 21-5). There was, however, some reduction in survival of 

 megalopa maintained in 1.0 ppm MONO-585 coupled v^th all three cyclic 

 temperatures. The greatest reduction in survival occurred when the compound 

 was combined with a salinity of 35.0 ppt, but this effect was reduced when the 

 cyclic temperature was increased to the maximum level of 30-35'^C. 



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