tion of stations, frequency of observation, and similar details. In addi- 

 tion to the observation of physical conditions at the time of sainpling, 

 samples were taken regularly for chemistrj'', phytoplankton, zooplankton, and 

 bottom organisms. Bacteriological samples were taken at less frequent and 

 regular intein^als. The details of methods employed in the field and labora- 

 tory will be presented in the various chapters dealing with results. 



Season of 1930 



In 1930 field investigations on fishes were discontinued, and the 

 fisheries staff was engaged in studies of the collections made in the two 

 preceding years. The limno logical program was continued along essentially 

 the same lines as in 1929. 



The scientific staff was as follows: 



E. L. Uickliff , Chief, Bureau of Scientific Research, Ohio 

 Division of Conservation. (Director of the Survey). 



Stillraan Wright^ United States Bureau of Fisheries. (In charge 

 of linnological investigations). 



C. J. Munter, Ohio State University. (Chemistry). 



Doris Ann Wright, Ohio Division of Conservation. (Zooplankton). 



Barbara Metz, Winthrop College. (Phytoplankton) . 



Elbert H. Ahlstrom, Marietta College. (Bottom organisms). 



Lee S. Roach, Ohio University. (Bottom organisms). 



Headquarters were established at the Fran?. Theodore Stone Laboratory on 

 Gibraltar Island, Put-in-Bay. The first observations were made on April k, 

 and the last on October 3. The full staff was in residence from June l5 to 

 September 1^5 in the remaining time the program was carried out on a reduced 

 schedule. Aside from the discontinuance of bacteriological work, and expan- 

 sion of chemical work, the program in this year was essentially the same as 

 in 1929. 



In the following section will be given the plan of investigation fol- 

 lowed in 1929 and 1930, for the reason that it serves as an introduction to 

 most of the chapters of the report. In the years prior to 19^9, the plan 

 was somewhat different. However, in presenting data for the earlier years, 

 those will be selected which fit into the scheme of 1929 and 1390. In that 

 way it is possible to attain a degree of uniformity in presentation. 



Plan of Investigation 



The general plan of investigation followed in 1929 and 1930 was based 

 on a knowledge of the lake gained in the earlier years. It had been found 

 that there was definite evidence of heavy pollution near the mouths of certain 



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