INTRODUCTION 



The Joint US-USSR Agreement on Cooperation in the Field of Environ- 

 mental Protection was established in May 1972. These Proceedings result 

 from one of the projects, Project 02.02-1.3 "Effects of Pollutants Upon 

 Aquatic Ecosystems and Permissible Levels of Pollution". 



The project derives its strength and value from the idea that it is 

 important for scientists who share a concern for the environment to take 

 a broad look at the subject, and to exchange views with their colleagues. 

 It is hoped by this process to help assure that the overall goals are not 

 lost in the clutter of minutia. These Proceedings cover Working Group 

 II 's first meeting of specialists October 21-23, 1975 at Duluth, 

 Minnesota. 



VI 



