The Productk'iiy of Fish Food in Oneida Lake iii 



small number of Galbo and Flanorhis is especially notable. 

 Pisidia decrease to two species and but a small fraction of a 

 per cent of the total number of individuals. The small number 

 of associated animals is also a feature influenced by depth, 

 chironomid larvcC and Hyalella forming 5S.2 per cent of the 

 associated animals. 



The increase with depth of the relative numbers of mollusks 

 over associated animals is striking, and is shown below: 



Depth in feet Mollusks Associated animals 



6-12 51 -33 per cent 48.67 per cent 



13-14 79-39 per cent 20.61 per cent 



14-18 84.26 per cent 15-74 per cent 



The number of species and the quantity of algje decrease 

 with depth, Spirogyra being the only species noted in water 

 deeper than 12 feet. This is probably one of the causes of the 

 decrease in animal life at this depth. 



4. Quantitative Data for Mud Bottom. The average popula- 

 tion of the mud bottoms is shown in Table No. 38. On the 

 basis of these averages the total animal population of the mud 

 areas is calculated to be :* 



No. of Associated Average 



units Depth Mollusks animals Total Acres per acre 



27 I- 6 feet 114,342,386 101,275,693 215,618,079 15 14,374,538 



II 6-12 feet 305,203,140 289,178,505 594,381,645 375 1,585,018 



2 12-15 feet 217,264,530 56,361,992 273,626,522 294 030,359 



Total 636,810,056 446,816,190 1,083,626,246 



* The computations for these are as follows : 



1-6 feet; 6,272,640 square inches in one acre X 15 acres = 94,089,600 

 square inches in 15 acres ~^ 16 (sq. in. unit )== 5,880,600 unit areas, 

 X 19.44 mollusks = 114,342,386 mollusks, and X 17.22 associated ani- 

 mals = 101,275,693 associated animals, -1-114,342,286 mollusks = 

 215,618,079, total calculated animal population. 



6-12 feet; 6,272,640X375 = 2,352,240,000 square inches -^- 16 = 

 147,015,000 unit areas, X 2.076 = 305,203,140 mollusks, and X 1.967 = 

 289,178,505 associated animals + 305,203,140 = 594,381,645, total animal 

 population. 



12-14 feet; 6,272,640X294=1,844,155,160 square inches in 294 

 acres ^ 16= 115,259,697 unit areas, X 1.885 = 217,264,530 mollusks, and 

 X .489 = 56,361,992 associated animals -|- 217,264,530^273,626,522, total 

 animal population. 



