Lake Maxhiknckee, Physical and Biological Survey 



221 



CHEMICAL CHARACTER OF THE WATER IX LAKE MENDOTA, WI SCON SIN 



Station II, September 18, 1907, 9-11 a. in. 

 Sky, cloudy; rain. 

 Wind, light breeze from the south. 

 Secchi disk visible at depth of 6.5 feet. 



DEFICIENT IN OXYGEN ONLY FOR A BRIEF PERIOD EACH YEAR 



Investigations have shown that Lake Maxinkuckee is deficient 

 in oxygen only during a period of perhaps two months in the fall. 

 The reason for this deficiency is a very interesting one and not dif- 

 ficult to understand. It may be briefly stated as follows : Lake 

 Maxinkuckee furnishes an environment exceptionally favorable to 

 the rapid growth and development of a multitude of species of 

 minute animal and plant life which together constitute the plank- 

 ton of the lake. These animals and plants, entomostracans and 

 other minute animals (zoo-plankton), and alg^e of many species 

 (phyto-plankton) , literally swarm in the lake, reproducing with 

 such marvelous rapidity that they would soon fill the lake, convert- 

 ing it into a thick soup, were it not for the fact that millions upon 

 millions of individuals die every day, their dead bodies slowlj^ sink- 

 ing to the bottom of the lake where they slowly oxidize and dis- 

 integrate. This accumulation of dead plankton goes on during the 

 spring and summer ; oxidation is doubtless most rapid in later sum- 

 mer and early fall ; the oxyg'en required in the process must neces- 

 sarily come from the supply contained in the water nearest at hand. 

 This drain upon the absorbed oxygen of the waters in the deeper 

 parts of the lake must inevitably, sooner or later, exhaust the sup- 

 ply, and this condition of exhausted or reduced oxygen content 

 will remain until the winds and storms of late fall and early winter 

 and temperature changes result in thoroughly mixing the waters 



