5. Borers are not equally sensitive to the effects of pollntioni Limnoria 

 trlgunctata and Teredo diegensis can maintain themselves for consider- 



■' . - able periods at ccncentrations of dissolved oxygen belov; three parts 

 per million. Limnoria quadripunctata , which thrives in cooler \vaters, 

 is absent from areas of' low dissolved oxygen (high pollution), Chelura 

 terebrans is confined to relatively clean v;aters, Bankia setacea main- 

 tains itself only in the coldest v/aters so that one gets no conclusive 

 evidence of its relation to the pollution from observations at the iso- 

 therms of Los Angeles. 



6. Liimori a tripunctata and particularly Te redo diegensis occur in great 

 numbers and increase rapidly in an area of high pollution, 



7. Foulinc: organisms also show a differential sensitivity to pollutants, 

 the hydroid, Obelia dichotoma , appearing to be most hardy. 



8. Pollution adequate to check borer and fouling activity completely is 

 paralleled by an accelerated corrosion of harbor equipment. 



I - p 



