Interrelationships of Fishes 

 and Lake Habitats 



Several types of artificial aquatic habitats were described in the pre- 

 ceding chapter. Now we will consider some of the components that make 

 up an aquatic habitat, and the relationships of these components with 

 fishes. 



Water in a habitat for fish must carry dissolved useful gases, minerals, 

 and other substances of kinds and amounts nontoxic to fish. However, the 

 habitat also consists of physical features, basically the contours of the 

 lake basin, with depths, high ridges, rocks, gravel beds, silt areas, marl 

 deposits, stumps, and fallen trees. Growths of submerged aquatic plants, 

 filamentous algae, and shoreline vegetation are a part of the physical 

 habitat as well as of the biological environment. Other parts of the bio- 

 logical environment include the bacteria, plankton algae, fungi, aquatic 

 invertebrate fauna, and a few kinds of vertebrates other than fish. Some 

 of these organisms are foods, some are enemies, and others change with 

 time— being enemies of small fishes first, and later, as these same fishes 

 grow, becoming their food supply. 



As indicated in Chapter 2, artificial lakes, being proximate to man 

 and recent in origin, harbor many abnormal and temporary ecosystems, 

 since plant and animal lake inhabitants may be either slow or rapid in- 

 vaders, and the stocking of fish by man is limited to the species he wants. 

 In fact, man usually leaves it to other fish to find their own way into the 

 lake he has created. Moreover, some aquatic forms that shun association 

 with man seldom appear, and others that he dislikes are not permitted 

 to enter ( or at least to remain ) . 



The status of a fish species in an artificial lake may be directly related 

 to its ability to compensate for the point of greatest maladjustment with 

 its environment. The population density of fish of its own kind or of other 

 kinds may be a factor in maladjustment to a given environment, as there 



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