the undertaking is owing to such contributions, and they are gratefully 

 acknowledf.ed. A number of thes-e have been of such outstanding importance 

 as to require individual mention. 



Although the Franz Theodore Stone Laboratory Wa.s one of the cooperat- 

 ing organizations engaged in the survey, it is fitting that acknowledgment 

 of the important role of the laboratory and its staff be made to the director, 

 Dr. R. C. Osbum. 



A number of employees of the Ohio Division of Conservation were asso-- 

 ciated with the survey for the entire period. Harry C. Crossley and George 

 F. Miller, as well as the men working under their direction at Sandusky and 

 Put-in-Bay, extended many courtesies and material aids to the scientific 

 staff. Special thanks are due Robert Shortliff, captain of the Investigator 

 in 1928, 1929 and 1930, who rendered services far beyond the dictates of 

 duty. 



Many scientific investigators in institutions not associated idth the 

 survey made valuable contributions. Those who performed services in a 

 restricted field will be mentioned in the introductions to the appropriate 

 chapters of the report. Professor Chancey Juday, of the University of 

 Vfi.sconsin, has corresponded frequently with the writer concerning the pro- 

 gress of the work, and it would be difficult to overestimate the value of his 

 counsel. Professor Jacob Reighard, Professor Emeritus, of Zoology, Univer- 

 sity of Michigan, generously permitted the use of data from his unpublished 

 report on pollution in the lower part of River Raisin. Dr. Paul S. Welch 

 of the Zoology Department, University of Michigan, loaned a number of pieces 

 of equipment, and was very helpful in an advisory capacity. Dr. Carl L. 

 Hubbs, of the Museum of Zoology, University of Michigan, loaned chemical 

 equipment and made nan y helpful suggestions. Finally, the writer wishes to 

 acknowledge the innumerable services rendered by his colleagues in the Ann 

 Arbor office of the United States Bureau of Fisheries. 



PHYSICAL LIMNOLOGY OF WESTERN LAKE ERIE 

 Hydrography 



Lake Erie is one of a series of six large lakes known as the Great 

 Lakes of North America. The lakes lie in the drainage basin of St. Lawrence 

 River, and constitute the largest group of connected bodies of fresh water 

 in the world. Lake Superior, the largest and deepest of the lakes, forms 

 the head of the system (Table 1). It discharges into Lake Huron through 

 St. Mary's River. Strictly speaking, Lakes Michigan and Huron constitute one 

 lake, for their surfaces have the same elevation, and the lakes are intimate- 

 ly connected by the Straits of Mackinac. Lake Huron is drained by St. Clair 

 River, which discharges into Lake St. Clair, the smallest and shallowest 

 lake of the system. Detroit River is the connecting link between Lake St, 



22 



