44 



LIMNOLOGY, WATER SUPPLY AND WASTE DISPOSAL 



• Soft Bettca 

 O Ila4 Isttaa 



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Graph 9. Total Sphaeriidae, log. (no./sq. ft. x 100) 



centration of toxicants. While they apparently resist high concentrations 

 of waste sulphite liquor, they do not inhabit the zone immediately below 

 the industrial sewer outlet. Within 3 miles, they reappear in concentrated 

 population and persist beyond the 32 mile station. 



Graph 10. Population of Asellus, log. (no./sq. ft. x 100) 



