140 



PROBLEMS OF LAKE BIOLOGY 



:r 



^ Cotost'omus commersonnn 

 a Cyprinus corpio 



J I L 



■CO COi mm. Hg. 



o Catostomus commersonnn 

 • Cyprinus corpio 



J L 



i'oo 300 Aoo COi fxp-r 



100 cOg pp.m. 



f?e/ofion beru/een 

 PcOa and Pd of 

 so% so/'urotion For 

 drown b/ood of the 

 sucker and the carp, 

 (from Block) 



e 



1 s 





C3 

 O Sj 



o 



f?e/ation between 

 COi concentrat'ion 

 ond lethal le^el of 

 Oi in the sucker 

 ond the carp. 



100 aoo 300 ^00 COz p.p.m. 



Specific differences in sensihvity totvords CO^ 



Tivo Species in the some habitat' 



Ti^o spec/es in 

 Oi/erlopping hobito/'s 



Paces in different hobifok . 



o Chrosomus eos 

 • Pfrille neogoea 



oBoleosomo nigrum 

 •Poeci/ichlhys exilis 



J L 



Chrosomus eos 



o spring stream 



• bog lake 



^"r=*y 



£oo 300 ^00 CO^ p.p.m. 



100 ^00 joo 



CO^ pp.m. 



£00 joo ■ioo COi fxpm. 



Fig. 3. Specific differences in the ability of fish to take up oxygen in the presence of carbon dioxide 



(from Black 1938 and Fry and Black 1938.) 



cific variation in sensitivity but the order 

 of the species is completely different. 



The concentrations of carbon dioxide 

 used by Powers, and by Fry and Black lie 

 almost completely out of the ecological 

 range, yet the species measured, which in- 

 clude among them nearly all those living in 

 Lake Opeongo, Algonquin Park, show a 

 sensitivity which is directly correlated with 



their vertical distribution in lakes in sum- 

 mer. Species most sensitive to carbon di- 

 oxide are found in the hypolimnion, species 

 least sensitive are found in the weedy shal- 

 lows. This correlation cannot be due to a 

 causal relation between the stratification of 

 dissolved gases and the sensitivity of the 

 fish towards them for the gradients of car- 

 bon dioxide and oxygen are the reverse of 



