0.020 



0.010 



0.0C3 

 0.002 



0.00 1 

 O.CCC 



NET PLANKTON VOLUME 



PONDS 



-^ 



6 PO/V05 



4 PONDS 



CLEAR 



-25PPM 



INTERMEDIATE 

 44-t6 PPM 



MUDDY 

 II6-2M PPM 



Figure 3. Average volumes of net plankton in surface waters 

 of three categories of farm ponds as determined from monthly 

 samples taken from April to October, 1954. 



