120 



PROBLEMS OF LAKE BIOLOGY 



greater bulk of tissue in the dominant spe- tlie hydrographic age of lakes, and the 

 cies of the southern lakes, and (3) there vegetation of lakes; also, a correlation ex- 

 are also greater areas of lake bottom eov- ists with the fish life. This is shown in the 

 ered b}' the i)lants in these lakes. following chart. 



Economic Considerations 



Reighard (1915), Baker (1918), Mutt- 

 kowski (1918), C. B. Wilson (1924), and 

 others have shown that the presence of 

 rooted aquatic plants is very important in 

 lakes and ponds where aquatic animals are 

 to thrive. To the invertebrates the vegeta- 

 tion serves not only as "cover," but also 

 as a source of food. The larger animals are 

 feeders upon the invertebrates and conse- 

 quently indirectly depend upon the plants 

 for food. 



Reighard (1915) discussing the distribu- 

 tion of fishes in the Douglas Lake region 

 of Michigan shows that three species are 

 found in the neighborhood of stony shoals, 

 five species frequent the deep waters, and 

 that ten species are found associated with 

 the submerged vegetation. 



Muttkowski (1918) observed in Lake 

 Mendota that in the bottom areas popu- 

 lated by plants the fauna was more abun- 

 dant and varied than elsewhere. 



Discussing the submerged vegetation of 

 Oneida Lake, Baker (1918) states that the 

 greatest development of plant and animal 

 life is within the six-foot contour. He 

 points out that each plant is important to 

 the lives of a host of animals, the primary 

 food of which is such plants. 



The part played by the emersed aquatic 

 vegetation in the biology of certain inver- 

 tebrates has been studied by Frohne 

 (1938). The number of species of insects 

 he found living upon these plants is shown 

 below : 



^ Species of 



Plants 



INSECTS 



1. Scirpus occidentalis 24 



2. S. valiclus 9 



3. S. americanvs 10 



4. Eleocharis palustris, var. major 9 



5. Carex vesicaria 10 



6. Fliragmites communis 6 



Pearsall (1921, 1929) discussing the 

 vegetation in the lakes of England has 

 stated that there is a correlation between 



A somewhat similar chart has been con- 

 structed for the lakes of Wisconsin. In this 

 is shown the characteristic vegetation in 

 lakes of certain physical and chemical de- 

 scription, and the types of fish most abun- 

 dant in them. Should this chart prove cor- 

 rect upon further investigation, it might 

 serve as a help to the stocking of lakes with 

 game fish. 



Aquatic vegetation is not only important 

 to those animals which spend all or part of 

 their life histories below the water, but also 

 to many of the larger vertebrates. Of these, 

 ducks, fur bearing animals, and large game 

 are the most important. These animals are 



