UNCLASSIFIED 
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bioassays as: Tolerant (24-hour LCj9 > 10 grams per liter), sensitive 
(10 grams per liter > 24-hour LCj9 > 1.0 gram per liter), or highly 
sensitive (24-hour LC, 9 < 1.0 gram per liter) to fuller's earth suspen- 
sions. 
Generally, bottom-dwelling fish species were most tolerant to sus- 
pended solids; filter feeders were most sensitive. Early life stages 
were more sensitive to suspended solids than adults; filter feeders were 
most sensitive. Bioassays with natural sediments indicated that suspen- 
sions of natural muds affected fish in the same way as fuller's earth, 
but higher concentrations of natural material were required to produce 
the same level of response. 
The effect of finely divided solids on fish was dependent on concen- 
tration, particle-size distribution, and angularity of the suspended 
particles. The cause of death was the same in all experiments--anoxia. 
This study provides base-line information for preproject decision- 
making based upon the anticipated concentration of suspended sediments 
at the project site and the effect of various lengths of exposure on 
estuarine fish of different life-history stages and habitat preference. 
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UNCLASSIFIED 
