Ecological Effects of Carbon Dioxide 265 



together. R. E. Coker (1938) on the occasion of his retirement as 

 president of the Ecological Society of America expressed this thought 

 in the following way: 



It seems to have been the work of a Divine Providence to cover the 

 greater part of the earth with the seas and at the same time to endow man- 

 kind with no means of making any great change in them. "I will give you" 

 he might have said, "dominion over the lands, over the beasts of the field 

 and the birds of the air, and over the shrubs, trees and grasses, but over 

 the oceans you shall have no control. I trust you with small things, but the 

 greater part of the surface of my beloved mundane sphere I shall keep 

 under my own lock and key. By means of the seas, which you can not 

 measurably modify, I shall protect you against your own follies." So the 

 undisturbed high seas remain the great balance wheel of the terrestrial ma- 

 chine, the chief source of the rainfall necessary for the continuance of or- 

 ganic life on land, the real fountain head of the water whose return journey 

 to the ocean carries the power required for our industries, the mainstay in 

 regulation of temperature, the molder of climates. Concerning the signifi- 

 cance of the seas to organic life anywhere, I do not need to say more to 

 cHmatologists, geologists, or biologists. Suppose that man could have put 

 his plow and machinery and his chemical reagents to work on the whole sur- 

 face of the earth. Might he not long ago have decided that such a great 

 expanse of brine was an error in Creation, as he has in effect concluded, 

 and perhaps properly, with reference to the great areas of forests and grass- 

 lands? Might he not have converted the saline waters into some other 

 chemical form? Think how much more tasty or more useful the sea wa- 

 ters might be were they turned into 20 per cent alcohol, for example, or 

 into gasoline; and we might have had now to form a committee for the 

 preservation of some small marine areas to be kept always as scientific "con- 

 trols" and as refuges for the native population of non-alcohol addicted and 

 non-gasoline tolerant diatoms, coccohthophores, Salpas, etc.— very useless 

 things in the eye of the practical man, but none the less interesting to the 

 field biologist. 



But the designer of nature gave us no opportunity to bring such things to 

 pass. "No," he might have said, "you may change the virgin grasslands 

 into desert, you may pollute the waters and dam the streams as much as you 

 please. You may accomplish much that is good by doing these things 

 wisely. You mean well, but all the same, and for reasons that are quite sat- 

 isfactory to myself, I put quite out of your reach the seas as the mainstay 

 of organic life on your planet." And this is not as facetious as it may 

 sound. 



Ecological Effects of Carbon Dioxide. The most fundamental 

 effect of carbon dioxide in the aquatic environment is the part that it 

 plays in the photosynthesis of green plants, just as is the case on land. 

 We have seen that in most natural waters as in the atmosphere the 

 amount of free carbon dioxide is very small. In sea water with a pH 

 of 8.3, for example, less than 1 per cent of the total carbon dioxide 

 is present in the free form (Fig. 7.9). However, both sea water and 



