FISHERY BULLETIN: VOL. 73, NO. 1 



40 





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40 



10 20 



30 



40 



SALINITY ( %„ ) 



Figure 2. — Response surface estimation of percent survival 

 of Crassostrea virginica veliger larvae after 8 days of 

 development at experimental temperature and salinity com- 

 binations given in Davis and Calabrese (1964). 



IT 



3 



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30 



20- 



100 



,80' 



y" 4 



-^ A 



y y 



.y y ^ 

 y y 



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10 20 30 



S ALIN I TY (%„) 



40 



Figure 3. — Response surface estimation of percent growth 

 of Crassostrea virginica veliger larvae after 8 days of 

 development at experimental temperature and salinity com- 

 binations given in Davis and Calabrese (1964). 



survival and growth indicating a significantly 

 higher salinity range is required for optimum 

 growth than is required for optimum survival. 

 An analysis of combined 8-day-survival and 

 growth data indicated that the linear effect of 

 temperature, the interacting effect of tempera- 

 ture and salinity, and the quadratic effect of 

 salinity were the more important factors ex- 

 plaining the data. Optimum (80^ contour) tem- 

 perature and salinity conditions for maximizing 

 both larval survival and growth was estimated 

 at above 30°C and between 18 and 35%o. 



Mercenaria mercenaria 



The same experimental design with the ex- 

 ception of nine levels of temperature and six 

 levels of salinity was used by Davis and Calabrese 

 (1964) to study the larval tolerance of this species. 



Survival to 2 days of development, or from 

 fertilization to veliger stage larvae, was affected 

 most by the quadratic effects of salinity and 

 temperature, and the interacting effect of tem- 

 perature and salinity. Tbe response surface for 

 2-day-old larvae clearly shows the skewed con- 

 tours resulting from the interaction effect 

 (Figure 4). Maximum survival to 2 days of 

 development (100% survival contour) was esti- 



mated to occur at temperatures and salinities 

 above 7.2°C and 28%o. Their experimental data 

 show maximum survival between 17.5° and 

 30°C at a salinity of 27%o. 



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10 20 30 



SALINITY ( %„ ) 



40 



Figure 4. — Response surface estimation of percent survival 

 of Mercenaria mercenaria larvae after 2 days of develop- 

 ment at experimental temperature and salinity combinations 

 given in Davis and Calabrese (1964). 



88 



