LU 



_I 

 GQ 



OLIGO- 

 SAPROBIC 



/3-MESO- 

 SAPROBIC 



a-MESO- 

 SAPROBIC 



POLY- 

 SAPROBIC 



DEGREE OF POLLUTION 



Figure 3. Relationship between degree of purification, pollution, number 

 of species and disturbance of aquatic ecosystem. 1 -Expenditures for 

 treatment of waste waters, flood waters, and other pollutions; 

 2-Number of species in ecosystem; 3-Degree of disturbances 

 in aquatic communities and ecosystems. 



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