The Plankton Algae of the Palisades Interstate Park 107 



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Plumecke: Arch. f. Hydrobiol. u. Planktonkde. 11 : 5.3-80. 1914. 

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2: 1-191. 1908. 

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Physical and Chemical Factors Affecting the Growth o£ 

 Blooms. Since the organisms causing the blooms in lake waters 

 are plants, they are governed in a general way by the same factors 

 that govern the growth of plants on land. It follows, therefore, 

 that a given volume of water can support only a certain number of 

 plants in the same way that a given area of land will support only 

 a certain plant population. In water as on land, when there is an 

 abundance of food materials there will be a greater crop of plants. 



Light and Chemical Relations. One of the primary conditions 

 for grO'Wth of plants is light, since it is through the agency of light 

 that the plant is able to carry on the process of photosynthesis, or 

 the combination of carbon dioxid and water into the food essential 

 for growth. It is well knov^ai that in water there is a considerable 

 absorption of light as it passes downward. The results of Pieten- 

 pol ('18) show that the amount of light absorbed varies from lake 

 to lake, that of lakes with a brown color or marsh stain being much 

 greater per unit of depth that that of a clear-water lake. There is 

 also a differential absorption of the various colors of the sun's spec- 

 trum, absorption of red rays being greater than that of the blue 

 rays in lakes with clear water, while the reverse is true in lakes 

 with dark waters. For all practical purposes the formation of new 

 plants is correlated with the formation of food materials. This zone 

 in which food manufacture may take place, the zone of photo- 

 synthesis, has been estimated by Birge and Juday ('11) as ten 

 meters thick in clear-water lakes, and two to three meters thick in 

 highly colored or turbid lakes. 



