TABLE 7-1 Development (ecesis) 

 of invertebrate bottom 

 populations (calculated In 

 number per m') in strip-mine 

 ponds of different ages, as 

 determined by studies conducted 

 in October, through three years. 

 The ponds I and 8 years old had 

 no rooted vegetation; the ponds 

 2! and 30 years old had a 

 little vegetation in protected 

 coves; the pond 80 years old 

 had submerged, floating, and 

 emergent vegetation. Range of 

 pH: 7.1 to 8.5; locality, near 

 Danville, Illinois. 



Although plankton distribution does not vary with 

 depth as much in ponds as in lakes, seasonal fluctua- 

 tions are as extensive and similar in nature. Eddy 

 (1934) lists 15 perennial species of zoo- and phyto- 

 plankton that may be found in ponds throughout the 

 year, 2 seasonal species which reach their peak of 

 abundance between December and April, 4 between 

 February and June, 12 between March and Decem- 

 ber, and 5 between July and September. 



Benthos 



Subaquatic animals dwell not only on the bot- 

 tom but also on the stems and leaves of submerged 

 plants. Aquatic plant species have many kinds of in- 

 sects, amphipods, mites, and snails using them for 

 the food, shelter, or reproductive sites denied them 



in the mud bottom below. Other kinds of insect lar- 

 vae and oligochaetes are more abundant in the mud 

 than on the plants. The undersurface of lily pads 

 often contains many small organisms, including Pro- 

 tozoa, Hydra, flatworms, rotifers, and snails. The 

 biomass of animals varies directly with the biomass 

 of vegetation, and the quantity of invertebrates is 

 especially great on those plants possessing finely dis- 

 sected leaves (Gerking 1957). Very few species 

 found in lake bottoms are not found in ponds, but 

 the pond-marsh biocies contains many species not 

 found in lakes. 



The variety of species and number of individuals 

 found in the bottom fauna increase with the age of 

 the pond from the time the pond is formed until at- 

 tached vegetation becomes excessive (Tables 7—1, 

 7-2). Coincident with the development of the bottom 



82 Habitats, communities, succession: 



