Three food chains of differing natures were described by Smith and Swingle 

 (I9J4O) s 



Phytoplankton ) 

 Stnall organisms) 



Bacteria ) 

 Phytoplankton) 



Bacteria ) 

 Micro fauna) 



(Golden shiner 

 (Gizzard shad 

 (Goldfish 



(Zooplankton ) 

 (Insect larvae) 



(Plankton) 

 (Insects ) 



(Bluegill 

 (Small crappie 

 (Small bass 



( ) 



(Small fish) 



(Largp crappie 

 (Large bass 



These examples are given to illustrate some approaches taken in con- 

 sidering the biological fate of nutrients. Ball (19h9) concluded that food 

 habits (of fish) nearer the base of a food chain result in a greater increase 

 of fish. It thus seems axiomatic that shorter food chains result in larger 

 and more consistent fish returns. The cyclic behavior of populations is 

 another important characteristic of aquatic life closely related to the 

 succession discussed above. This advance and decline of numbers is most 

 oronounced among the lower organisms, and may take an erratic pattern. 

 The nature of such fluctuations is not well understood, but it should be 

 remembered that they may occur independent of nutrient addition. 



Final consi deration is given to productivity in vrhich the entire con- 

 cept of fertilization is embodied. The objective of artificial enrichment 

 is to increase the productive capacity of a body of water and so increase 

 the potential yield of fish,. Each environment differs ,n the amount of 

 living matter it is able to support. Lawson (1937) believed that superior 

 production is based on abundant microvegetation. Productive differences 

 among vraters are characterized by many factors, Wunder et al, (1935) 

 seated that good producing ponds have algal blooms in spring or early sum- 

 mer j, and that these blooms are continuous in the best producing oonds. 

 Various indexes of productivity are treated in another section, but it may 

 be stated at this point that the ultimate measure is the yield of desirable 

 fish per urj.t area and time. This productive capacity is realized only 

 when the crop is rermved. Fertilization places nutrients in the water and 

 oroductive anabolic processes transform them into fish flesh. It follows 

 that an expenditure of time and energy on fertilization will be profitable 

 only if the water is cropped and the fish utilized. 



Chemical Considerations 



The chemical aspect of the aquatic environment is, by far, the most 

 important consideration involved in the fertilization process, A brief 

 description of the chemical nature of lakes and ponds w ill later aid in 

 the understanding of nutrient interactions. The aquatic habitat can be 

 thought of as a quantity of water retained in an earthen bcwl. The re- 



