compare this lake with certain others for the period covered, and 

 thus reached some conclusion as to the relative richness of the 

 zooplankton per unit volume of water. 



There are no data from the open waters of the Great Lakes 

 which lend themselves to comparison with those reported here. 

 However, Burkholder and Tressler (1932) obtained some r esults with 

 a plankton trap in four bays at the east end of Lake Ontario. Three 

 sets of sam.ples were taken at each of six stations on the following 

 dates in 1931: June 25, July 15 or 17, and August 17 or 19, 

 Samples were taken at the surface and bottom, and the results are given 

 in graphic form, divided into three grouns: Copepoda, Cladocera, and 

 Rotif era (their Figure 10) , In Black River Bay, near the mouth of 

 the river, the plankton was rare, but farther out at a depth of l6 

 meters, the mean counts for the three dates were: Copepoda (apparently 

 including nauplii), 19 per liter; Cladocera, 3 per liter. In the 

 Island Section of Lake Erie, for a corresponding period of time (late 

 June - late August) of two years, the mean counts including the 

 abundant genera only, were: Copepoda (including nauplii), U2 per 

 liter; Cladocera, 7 per liter. The great abundance of Crustacea in 

 Lake Erie is offset to some extent by the rarity of rotifers: 7 per 

 liter as compared with 36 in Black River Bay. Further, it should be 

 noted that the figures for Black River Bay are based on surface and 

 bottom samples only; the adult Crustacea are usually most abundant at 

 intermediate levels, so that the figures probably are too low. Two 

 stations in Chaumont Bay (3 to 6 meters) yielded mean counts as 

 follows: Copepoda, 31; Cladocera, 3; Rotif era, 73 per liter, Muskalonge 

 Bay (2,5 meters) showed the greatest abundance of plankton: Copepoda, 

 Ii2, Cladocera, 37, Rotifera, 72 per liter. Similar counts were recorded 

 for a shallow station in Three Mile Bay, except for the Cladocera, which 

 were rare. While these figures are somewhat unsatisfactory for purposes 

 of comparison, principally because the nauplii are included with the 

 adult copepods, it seems probable that the bays studied by Burkholder 

 and Tressler are not excessively rich or poor in zooplankton as compared 

 with the Island Section of Western Lake Erie. 



More satisfactory comparisons can be made with three inland 

 lakes of Wisconsin which have been studied in detail. The three lakes 

 selected are Lake Mendota, studied by Birge (I898), and Green Lake 

 and Lake Winnebago, studied by Marsh. (1903) . Lake Mendota is a rather 

 shallow lake (25.6 meters) of the eutrophic type, while Green Lake is 

 a deep lake (72.2 meters) of the oligotrophic type. Lake Winnebago 

 resembles Western Lake Erie in having a great surface area 

 (557.5 square kilometers) and meager depth (6.I1 meters maximum), 



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