WOEIKE ON PACIFIC OYSTER EMBRYO BIOASSAY 1 17 



584g 



OYSTERS 



WATER 



CONDITIONING 

 4-6 Weeks ot 20° C 



CARRY -ALONG 



4 Liter sea wotct 

 from loboralory. 



COLLECTION 



4 Liter somple 

 by seoplane. 



SPAWNING 



Temp, roised to 25° - 30° C. 

 for 2-3 hours; sperm added. 



TRANSPORT 



All samples to loboralory 

 within 3 hours of collection 



INOCULATION 



20 - 30 Thousands zygotes, 

 J'j hours old or less, added 

 to each culture. 



3 ONE-LITER CULTURES 



Incuboted ot 20°C 



for 48 hours. 



TERMINAL S.W.L. 

 AND SALINITY 



250 ml 



ALIQUOT SAMPLE 



Containing 100-200 lorvae. 



CHLOROPHYLL 

 500 m\. 



INITIAL S.W.L. 



AND SALINITY 



250 ml. 



INDEX 



Percent obnormal 

 lorvoe determined. 



FIG. 1 — Flow diagram for oyslcr larva bioassay. 



effect, 20, 50, and 100 per cent abnormals (response), were determined. 

 The Pearl-Benson Index (PBI), a chemical measure commonly used for 

 measuring pulp and paper wastes, was determined for each dilution of 

 each waste bioassayed. The results of this study are shown in Table 1. 

 In Table 2 these wastes are arranged in order from most to least toxic, 

 based on the amount of dilution needed to reduce their toxicity to 'he 

 20 per cent abnormal level. It should be noted that when ranked in this 

 manner, the PBI values for the waste dilutions designated do not follow 

 any particular pattern. This indicates that the PBI does not measure the 

 relative toxicity of the different wastes. To give a more practical de- 

 scription of these results, the gallons of dilution water needed to reduce 



