1922] Blum: On the Effect of Low Salinity on Teredo Navalis 351 



The chief aim of the present investigation has been to determine 

 the lethal, or death producing, salinity for this species of borer and 

 the period of survival in various salinities. 



This work has been carried on as a phase of the investigations of 

 the San Francisco Bay Marine Piling Committee, the particular 

 investigation being made possible by the kindness of the California 

 and Hawaiian Sugar Refining Corporation, who have provided the 

 experiment station and laboratory facilities. I wish here to 

 acknowledge the kind assistance of Mr. A. A. Brown, Construction 

 Engineer for the above corporation, and the invaluable advice and 

 supervision of Professor Charles Atwood Kofoid of the University of 

 ( lalifornia. 



Methods and Equipment 



The study of various factors affecting Teredo nurtilis was carried 

 on at the temporary experiment station on the dock of the California 

 and Hawaiian Sugar Refinery at Crockett, California. This station 

 included ninety individual aquaria, which were constructed from 

 wooden buckets of about two and one-half gallon capacity, each 

 equipped with a bar and wedge for holding the specimen in place 

 (fig. 1). The specimens used were sectors cut from sections of teredo- 

 infected piles; they were eight inches in length and three to four 

 inches in width across the outer or curved surface of the pile. A 

 supply of sea water was provided by pumping water from the straits 

 into two 10,000 gallon wooden storage tanks. Fresh water was 

 obtained from the supply of the California and Hawaiian Sugar 

 Refinery. This supply was obtained from surface water at Carquinez 

 Straits and the Sacramento River at the time these experiments were 

 conducted, and was subjected to treatment with aluminum sulfate and 

 to mechanical filtration prior to our use of it. A maximum of 10 

 parts per 100,000 of sodium chloride is allowed in this water before 

 treatment. The water of various salinities used in the following 

 experiments was obtained by diluting the stored water from the 

 straits with fresh water from the supply. 



The measure of salinities used is based on determination of chlorine 

 by titration with silver nitrate, the total salinity in parts per 1000 

 being obtained by reference to the international hydrographie tables 

 (Knudsen, 1901). The formula on which these tables are based is 

 S = 1.8050 CI + 0.030. This method of determining salinity is the 

 one used by the San Francisco Bay Marine Piling Committee (Kofoid, 



