Oppenheimer: Did you say the change in pH is a limiting factor: In the possi- 

 ble limiting of COoj might this account for the migration? You 

 remember that you found the organisms out in the mud flats 

 right below the surface. It is very possible that right on the 

 surface CO? is limited so they migrate back down into the sedi- 

 ment to where CO2 rnight be abundant, 



Pomeroy: They are migrating up during the period when they are exposed 



to the air, and that is when I am measuring this pH in air. 

 That is when they are up there, you see. 



Oppenheimer: I was thinking of this effect whenever you go out on sediments 

 you almost invariably find your green coloration about trwo or 

 three millimeters below the surface. 



Pomeroy: 



Chapman: 



Pomeroy: 



Odum: 



Pomeroy: 



Odum: 



Pomeroy: 



Odum: 



Pomeroy: 

 Odum: 

 Pomeroy: 

 Burkholder: 



That is true up in the marsh but it is not true when you get 

 down near the low tide level. 



Could I ask another question? When you had this setup on the 

 marsh and you have got your water in the bell jar, does the 

 water in the bell jar fall at all during the course of the experi- 

 ment or is the mud so compact that the water stays in? 



It stays there. I throw it away if I have a hole or anything 

 underneath which lowers the level at all. I discard about 50 

 percent of them for that reason. 



Is there competition between the winter which is mostly a 

 transient population and your summer which is mostly a water 

 population? I take it that is the case. 



You are suggesting that this is a different population? 



I am just trying to see if there is something else besides light. 



There might be a different population. I simply have not gone 

 into the taxonomy. 



Wait a minute, start over. You have a population of algae in 

 the water. 



Not in the water 1 am using for my measurements. 



So that's out. 



That's out. 



How did you get the population out of the water ? 



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