168 Theories and Techniques of Management 



If fertilization appears desirable in starting new ponds of low natural 

 fertility, the program should be stopped before undesirable plant growths 

 are evident. New gravel-pit ponds, stone-quarry ponds or dug ponds 

 having basins of raw clay are often poor fish-producing waters when first 

 formed. The addition of several hundred pounds per acre of commercial 

 fertilizer during the first year will improve fish production without creat- 

 ing nuisance vegetation problems in later years. 



AQUATIC VEGETATION AND CONTROL MEASURES 



The vegetation that develops in an aquatic environment is as char- 

 acteristic and specialized as that associated with any terrestrial habitat. 

 How then may aquatic plants suddenly appear in a new artificial lake, 

 which a few months before was a dry valley supporting only terrestrial 

 grasses and shrubs? Since the valley was flooded, the terrestrial plants have 

 disappeared and have been replaced by widespread floating mats of green 

 "scum" composed of one or several varieties of filamentous algae. In 

 shallow water are a few scattered plants of a fine-leaved pondweed 

 {Fotamogeton sp.), a higher plant that grows almost entirely below the 

 water surface and which cannot support its own leaves when it is lifted 

 out of water. 



How did these plants manage to suddenly appear in a location separated 

 from other standing water by miles of dry land? Undoubtedly, resting 

 cells of various kinds of algae blow about on winds. Seeds of certain 

 higher plants may be transported by special organs which allow them to 

 become airborne (as in the feathered seeds of the cattail). Still other 

 seeds which are covered with a very hard coat are eaten by aquatic 

 birds and pass through their digestive tracts undigested, only to fall to 

 the pond bottom and germinate in the next location visited by the bird. 

 It is conceivable that seeds and parts of plants might become entangled 

 with or stick to the muddy toes of aquatic birds and be carried for short 

 distances in this manner.^- Some seeds float from one location to another 

 through connecting water courses. Thus, during a flood period a pond 

 located well upstream in a watershed might furnish floating seeds to a 

 downstream impoundment. 



Aquatic plants get around in one way or another, and certain species 

 are likely to appear before others. Among the large emergent plants the 

 cattails usually appear first, perhaps because the seed-bearing "fuzz" of 

 the cattail head is so readily carried by the wind. 



Of the submersed pondweeds, the fine-leaved varieties usually appear 

 first, later to be followed by coarser-leaved varieties. Why this should be 

 so is unknown, although there is evidence that the new habitat is more 

 suitable for some species than others. This may be demonstrated by 



