Biological Survey — Genesee River 



15 



Oxygen and Carbon Dioxide Content. — Tn rapid, unpolluted 

 streams these factors need not be considered, because the amount 

 of oxyg'en contained in the water is in direct relation to the amount 

 of churnino- the water receives in ])assing- over obstructions. Hence 

 swift waters are generally saturated and thus suitable in this 

 respect for all fishes. Carbon dioxide, if present, is liberated from 

 water that is broken up by riffles and falls and consequently ra]^id 

 streams show only traces of the gas. 



However, in streams polluted by organic wastes, the oxygen 

 may be used up more rajiidly than it is dissolved from the air or 

 sui)plied by plant life. Tn the ]irocess of decomposition, carbon 

 dioxide may become excessive. There is therefore the double 

 danger of insufficient oxygen and too much carbon dioxide which, 

 when critical points are reached, are fatal to fish. Thus a deter- 

 mination of the oxygen and carbon dioxide content of streams 

 receiving organic wastes becomes an imj)ortant procedure. 



Tn lakes, especially those that might be suitable for lake trout 

 and whitefish. it is important to know something about the gaseous 

 content in depths frequented by these species. To illustrate, let 

 us compare two lakes in the Genesee system: (1) ITemlock lake, 

 which contains lake trout and whitefish in some numbers, and 

 (2) Conesus lake, in which they are known to be practical! v 

 absent. 



By reference to the tables of Birge and Juday (1912)^ it will 

 be seen that oxygen is lacking in the deeper parts of Gonesus lake. 



Table 3. — Observation ox Gasesi 



Depth in Meteis 



HEMLOCK LAKE, AUG. 



1910 



21.7 



21.5 



21.4 



19.8 



18.0 



15.2 



10.9 



9.8 



9.5 



9.3 



1.80 

 1.80 



1.30 

 'o;38 



3.29 

 5.06 

 7.10 



12.90 



6.77 

 6.93 

 6.92 

 7.02 

 7.42 

 7.73 

 5.36 

 3.80 

 1.37 

 0.70 



106.0 



10S.2 



107.8 



1(16.5 



108.9 



107.4 



68.2 



47 . 1 



16. S 



8.5 



CONESUS LAKE, AUG. 25, 1910 



21.8 

 21.6 

 21.4 

 20.3 

 16.4 

 15.5 

 14.6 

 13.2 

 12.5 



2.50 



4.04 



25.80 

 26.30 

 28.10 



6.16 

 6.12 

 6.00 

 1.50 

 0.11 

 0.05 

 0.06 

 Tr. 

 0.00 



96.6 



95.7 



93.5 



22.9 



1.5 



0.7 



0.8 



0.0 



> Birge. E. A., and Jiulay. (\ 

 New York — Bull. Bur. Fisherit 



l!tl2. 

 . Vol. 



A liniii.'l()iii( al stn<l.v of the Fin 



Lala 



