462 



W. T. Edmondson 



than in the relatively unconfined population of the tank. Nevertheless, under the 

 circumstances which existed, the bacterial population is probably similar in the two 

 bottles. Plate counts differed httle. Thus, the difference between the bottle popula- 

 tion and the tank population is that the former had a higher proportion of bacteria. 

 Any relation which would depend upon the ratio of bacteria to other organisms 

 would be modified. (See Ryther, 1954). 



Both the rate of disappearance of phosphate from the water and the rate of increase 

 of phosphorus in particulate form (organisms) showed a rather close relation with 

 net photosynthesis and with gross photosynthesis. In the latter measurements, 

 there were three pairs of points which diverged greatly from the general pattern, 

 because of a high rate of photosynthesis not matched by the high rate of phosphorus 



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 o 



X 

 a. 

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o 



X 

 a. 



4 

 -o- 





o .< 



J L 



o 

 o 



I I I 



I I I 



0-5 lO 



CROSS PHOTOSYNTHESIS 



1-5 



- O + O 5 



NET PHOTOSYNTHESIS 



lO 



Fig. 5. Rate of change of phosphorus as a function of gross photosynthesis (left) and net photo- 

 synthesis (right) in Experiment 3. Particulate phosphorus is shown by filled circles and phosphate 

 phosphorus by open circles. The rate of change of phosphorus is given as (xgrn at/l/day., photo- 

 synthesis as before. 



uptake (Fig. 5). The reason for the divergence of the aberrant points is not evident. 

 The data are for determinations made toward the end of the period of investigation, 

 and the rate of respiration was unusually high. It is possible that photosynthesis 

 was able to proceed rapidly, without a corresponding uptake of phosphate, because 

 of phosphorus stored in the cells (Ketchum, 1939). 



In both cases, the rate of increase of particulate phosphorus very closely matches 

 the rate of decrease of phosphate in the water. Individual pairs may not match well 

 because phosphorus can be lost from the particulate fraction without immediately 

 appearing as phosphate, but the fields of points do match. 



DISCUSSION 



The investigation partially summarized in this paper was intended primarily to 

 explore certain problems of aquatic productivity. The ideas discussed concern fresh- 

 water as well as marine populations. Extrapolation from pure culture work to natural 



