The Producih'ily of Fish Food in Oneida Lake 223 



percent. In the areas examined in the vicinity of Lower South 

 Bay the sand bottom in shallow water was the richest in indi- 

 viduals, averaging about no million per acre while the boulder 

 shore was the poorest, averaging about 4 million to the acre, 

 or less than 4 percent of the population of the sand areas. 



A striking feature of the plant life was the presence of large 

 quantities of filamentous alg?e which covered the bottom in 

 many places like a blanket, which greatly modifies the char- 

 acter of the bottom. It seems pnjbable that the great wealth 

 of life in Lower S(juth luiy is largely due to the presence of 

 this plant which provides a rich food supply for the inverte- 

 brate animals. The presence of such a quantity of algcC is 

 believed to be the reason that the higher jjlants were not made 

 of greater use. by the herbivorous animals. 



The great predominance of animals of herbivorous and 

 detritus feeding habits over those of carnivorous hal)its is 

 clearly shown, the former amounting to about 7,743 million 

 individuals and the latter to about 27, million individuals or 

 about .29 of one percent. This fact is important when it is 

 recalled that the herbivorous animals are producers and the 

 carnivorous animals are consumers of fish food. 



Another featvtre of interest brought out by the investigation 

 is the predominance of mollusks in individuals over any other 

 group of animals, the mollusks, in fact, surpassing in nvunber 

 all groups of associated animals combined. In figures, this 

 means 4,704 million mollusks, and 3,062 million associated 

 animals. The mollusks are therefore 30 percent greater in 

 number of individuals. This plurality of mollusks over asso- 

 ciated animals is indicated by Blegvad ('16, pp. 22, 23) for 

 marine quantitative studies. It was also fotmd that the mol- 

 lusks were subject to a limited migration, the young of some 

 species of Galba, Acella, PJiysa, and Planorhis living in water 

 from 6-14 feet deep, among algse, when young, and migrating 

 to the shore in shallow water when adult or nearly adult. It 

 w^as likewise observed that a large percentage of mollusks were 

 young or immature at this time of year (July). 



An attempt has been made to determine the number of fish 

 that this rich store of invertebrate animal life will feed. The 



