THE MACROPLANKTON OF LAKE ERIE 



Charles B. Wilson, Macroplanktonologist 

 Westfield Normal School, Westfield, Mass. 



CONTENTS 



Page 



Apparatus and methods 145 



Importance of the macroplankton 145 



Components and amount of plankton 146 



Horizontal distribution 147 



The marginal zone 147 



Breeding areas of the marginal zone .... 149 



Marginal organisms 152 



Copepods 152 



Cladocera 153 



Other Crustacea 153 



Other organisms 153 



Resume of marginal zone plankton 153 



Littoral and lacustric zones 153 



Littoral zone 153 



Lacustric zone 154 



Seasonal distribution of the macroplankton . . 154 



June distribution 155 



July distribution 157 



August distribution 159 



September distribution 161 



Species occurring in Lake Erie and its drain- 

 age area 163 



Non -parasitic copepods 163 



Parasitic copepods 166 



Cladocera 167 



Other Crustacea 171 



Comparison of Lake Erie and Victoria Nyanza 



macroplankton 172 



Macroplankton as intermediate hosts 172 



The following account of the macroplankton of 

 Lake Erie is the final summary of the survey of the 

 lake canied on during the summers of 1928 and 1929. 

 A condensed preliminary report of the work of 1928, 

 which included only a quarter of the lake at the ex- 

 treme eastern end, has already been published 

 (Fish et al. 1929). 



APPARATUS AND METHODS 



a Helgoland trawl towed on the bottom. The meter 

 nets were drawn simultaneously at each station for 

 5 minutes and as nearly at a uniform rate as possible; 

 no attention was given to the late of towing. The 

 macroplankton of the marginal zone was captured 

 entirely in 1-foot nets, No. 12 mesh, or by washing 

 out the sand and mud of the bottom and straining the 

 wash water through the net. One-foot nets. No. 20 

 mesh, were used for the microplankton of all 3 zones 

 and their contents were also examined for macro- 

 plankton to make sure that none of the smaller species 

 escaped. During the entire survey, however, the 

 only additions from these small-mesh nets were de- 

 velopment stages of the copepods and cladocerans. 



The meter nets and trawl were operated from the 

 steamers Navette and Shearwater . An automobile 

 trip was made around the entire margin of the lake 

 in August 1929 in order that the marginal zone inside 

 the steamer towings and the mouths of the numerous 

 creeks and rivers that empty into the lake might also 

 be included in the survey. During this trip frequent 

 stops were made wherever the conditions looked 

 favorable and both macroplankton and microplankton 

 were collected, the former by the author, the latter 

 by Ralph Buchsbaum. The marginal towing was done 

 from a row boat, by casting the net &om a wharf or 

 jetty, or by wading among the water plants and 

 scooping the net by hand. 



During 1928 the steamer trips included only the 

 eastern quarter of the lake, but during 1929 they 

 covered the entire lake as far west as Point Pelee on 

 the Canadian shore and Sandusky on the American 

 shore. The extreme western end of the lake was 

 under investigation during both years by the Ohio 

 Division of Conservation and the summer laboratory 

 of Ohio State University situated at Put -in -Bay. The 

 marginal zone collections, however, included some 

 from this western end as well as from the rest of the 

 lake. Four of the steamer trips during each year were 

 for the collection of plankton, one trip in June, July, 

 August, and September, respectively. The 1929 auto 

 trip was the only one that included the entire margin 

 of the lake, but repeated short trips were made during 

 both years to isolated localities within the marginal 

 zone. 



The macroplankton of the littoral and lacustric 

 zones was collected by two 1 -meter nets, one at the 

 surface and the other just above the bottom, and by 



IMPORTANCE OF THE MACROPLANKTON 

 The number of fish that can be supported in a lake 



145 



