Role of Bacteria in Mineralization of Phosphorus in Lakes 657 



nineteen hours, which means that in this interval as much or- 

 ganic phosphorus as was present would be expected to cycle 

 through the inorganic state. 



Additional information was obtained from an experiment in 

 which bacteria and higher plants were placed in competition for 

 added radiophosphorus. If filtered lake water is set up in the 

 light, control xalue will be similar to the top line of Figure 1. To 

 replicates under test are added a plant sprig with or without anti- 

 biotic as well. The loss of P^- from the water is shown in Figure 

 2. In the absence of bacteria, Eriocaulon very rapidly takes up 



UJ 



a. 



V- 



z 



o 

 o 



CONTROL 



-,-•■ 



ERIOCAULON 



aX 



ERIOCAULON 



a ANTIBIOTIC 



12 3 4 5 



DAYS 



Fig. 2. Radiophosphorus remaining in aerated water from Grand Lake, N. 

 S., containing plants, with and without antibiotic. One gm. of sprigs of 

 the flowering aquatic, Eriocaulon (pipewort) were added to 150 ml. of 

 filtered lake water. Similar results were obtained with the plants UtricuJaria 



and Sphagnum. 



