of these organisms (Table 70) . All of our knowledge of the plankton 

 of Lake St. Clair as compared with that of Lake Erie is derived from 

 samples taken in September, and the apparent poverty of the plankton, 

 relative to that of Western Lake Erie, may be due to an earlier decline 

 in the upper lake. But since the low counts at Station 126 on 

 September 23 were so obviously related to the low counts in Lake St. Clair, 

 it is only reasonable to suppose that a similar relation existed for the 

 consistently low counts recorded at Station 126 on other dates. That is, 

 it is highly probable that Lake St. Clair is always poor in plankton, and' 

 consequently the river which drains it is always poor in plankton. 



Although Station 13li is eight miles from Station 126, it is 

 included with Station 126 in the Detroit River Section because it 

 appears to be influenced strongly by the river. Samples were taken 

 here on six dates in 1929 and on five dates in 1930 (Table 79) • 

 Comparison of the counts in this table with those in Tables 69 and 70 

 for the Island Section, Table 75 for Section 25U, and Table 77 for 

 Station 117, shows that Station 13U was relatively poor in plankton 

 during both years. However, it had considerably higher counts than 

 Station 126 for most of the samples taken on the same day or within a 

 short period of time. The resemblance between counts at these two 

 stations was closer than between Station 13U and any other station 

 studied. This seems to indicate that Station I3I4 derives its water 

 largely from Detroit River, a s might be expected from the position of 

 the station and the immense discharge of the river. 



Comparison of abundance of zooplankton 

 in different sections of Western Lake Erie 



Study of the horizontal distribution of the Crustacea in the 

 Island Section of Western Lake Erie showed that the distribution was 

 not uniform. However, there was no evidence that certain stations 

 had consistently high counts and others consistently low counts. On 

 the other hand, there is definite evidence of large and fairly con- 

 sistent differences in abundance between different sections of the 

 lake. Some of the more obvious differences have been noted, such 

 as the rarity of organisms near the mouth of Detroit River, and the 

 great abundance in Maumee Bay as compared with the Island Section, 

 It seems advisable to make direct comparison of the sections at this 

 time, in order to bring out the differences more clearly. 



In presenting data on sections at the extreme west end of the 

 lake, only those for I929 and 1930 were included. The few data available 



2i;2 



I 



