liter; bluegill, Lepomis macrochirus, 2,010 mg/Iiter; 

 and the snail, Physa heterostropha, 940 mg/liter. Un- 

 fortunately, other bivalves appear to be more sensitive 

 to potassium. Imlay (1973:104) found that 11 mg of 

 potassium per liter of water was lethal to 90 percent of 

 Actinonaias carinata, Larnpsilis radiata siliquoidea, and 

 Fusconaia flava in 36-45 days of exposure, and 7 mg of 

 potassium per liter of water was fatal to the latter two 

 species in about 8 months. He also compared the distri- 

 bution of freshwater mussels with potassium levels in 49 

 U.S. rivers, and on the basis of his findings, he predicted 

 that the maximum safe level for most freshwater mussels 

 is 4-10 mg of potassium per liter of water. It might be 



possible to use potassium alone or in combination with a 

 mollu.scacide to treat troublesome populations of Asiatic 

 clams within intake structures or water s>'stems during 

 shutdowns for cleaning or maintenance without damag- 

 mg other organisms in the surrounding environment. A 

 potassium concentration could be selected that would be 

 high enough to affect Asiatic clams within the plant but 

 low enough to be diluted to nontoxic levels when dis- 

 charged into the en\^ironment. 



It is possible that potassium levels in rivers could 

 limit the distribution of Corbicula m. although more re- 

 search is required to determine the chronic effects of 

 potassium on this mollusk. 



LITERATURE CITED 



Finney, D. J. 1971. Probit analysis. 3rd ed. Cambridge Univer- 

 sity Press. 333 p. 



Imlay, M. J. 1973. Effects of potassium on survival and distribu- 

 tion of freshwater mussels. Malacologia 12(1) :97-113. 



Ingra.m, W. M. 1959. .'\siatic clams as potential pests in Califor- 

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 Journal 51 (3) :363-370. 



Innes, W. T. Exotic aquarium fishes. Innes Publications. 541 p. 



Litchfield, J. T.. and F. Wilcoxon. 1949. A simplified method 

 of evaluating dose-effect experiments. Journal of Pharma- 

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McKee, J. E., and H. W. Wolf, eds. 1963. Water quality 

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Mount, D. I., and W. A. Brungs. 1967. A simplified dosing ap- 

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Sinclair, R. M. 1963. Effects of an introduced clam (Corbicula) 

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Annual Sanitary Engineering Conference. Vanderhilt Uni- 

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1971. Annotated bibliography on the exotic bivalve 



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Sprague, J. B. 1973. The ABC's of pollutant bioassay using fish. 

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Taras, M. J., A. E. Greenberg, R. D. Hoak, and M. C. Rand, 

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