ABSTRACT 



Physical, chemical, and plankton data collected by the 

 M/V Cisco (U. S. Fish and Wildlife Service) in Lake Superior 

 in 1952 and 1953, temperature data obtained by the M/V Williams 

 (U. S. Lake Survey) in 1956 and 1957, and temperatures recorded 

 by thermographs during 1951-1957 are presented with limited in- 

 terpretation. 



Ion concentrations were low and varied little vertically, 

 seasonally, or from area to area. A relatively high plankton 

 abundance along the south shore from the Apostle Islands to 

 Grand Marais, Michigan, was related to relatively high phosphorus 

 concentrations. Much of this phosphorus may enter the lake at 

 Duluth. If so, it must be transported by an inshore current. This 

 movement furnishes evidence of a general counterclockwise cir- 

 culation as indicated by drift cards released in 1953. 



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