Long Point. Some of the surface sar^jles showed about 6 thousand units, 

 while at the bottom the counts were negligible. In July the group was 

 more evenly distributed, both horizontally and vertically, but was 

 quite rare. The central basin showed very few blue-greens in August, 

 while east of Long Point there v.'ere several stations with counts as high 

 as 5 thousand. In September this relationship was reversed, but few 

 stations had high counts. At no time or place did the blue-greens 

 approach the average abundance in the Island Section in September (Fig- 

 ure 15) . 



Making due allowance for che fact that Burkholder's records are 

 based on net rather than centrifuge sanples, the conclusion is inescap- 

 able that rt'estern Lake Erie is much more rich in plankton (per unit of 

 volume of water) than the part of the lake farther east. 



Reighard (I89U) reported that Lake Erie near the islands contained 

 about three times as much plankton per unit of volume as Lake St. Clair. 

 This conclusion was based on a few voliunetric determinations of the total 

 net plankton made in September. On September 23, 1930, coiuits were made 

 of surface and bottom centrifuge samples taken near the outlet to Lake 

 St. Glair. The total count was llli thousand units per liter. The 

 average count for the Island Section in late September - early October, 

 1930, vas U$2, or four times the count for Lake St. Clair. Both of these 

 comparisons are based on meager data, but they justify the conclusion 

 that Wescern Lake Erie is much more productive than Lake St. Clair in 

 September. On the basis of comparisons with Apstein's work on European 

 Lakes, Reighard considered both Lake St. Clair and Lake Erip plankton- 

 poor lakes. 



Judging by the volumetric determinations of the total plankton made 

 by Vfard (I896) , Western Lake Erie is more productive than Lake Michigan 

 in the Traverse Bay region. He found that the average volume of 

 plankton was about the same as in Lake St. Clair, but the shallow water 

 contained about twice as much, which still was less than the amount in 

 Lake Erie according to Reighard 's date. 



Eddy's (1927) data indicate great ab'ondance of phytoplankton 

 in the surface water along the south shore of lake Michigan. In 

 October, 1926, net collections at Sawyer, Michigan, and Michigan City 

 and Dunes Park, Indiana, yielded from I8 to 71 thousand -units of diatoms 

 per liter (ignoring rare forms) . Filter paper collections at Michigan 

 City gave a count of lii7 thousand units of diatoms. Greens and 

 blue-greens were rare. In May, 1927, net collections at Gary and 



175 



