A = MILL1P0RE FILTER 



B = ACTUAL FILTER COLLECTING AREA 



Figure 6. Diagram illustrating counting technique used for microplankton. Each square 

 depicts the field of the microscope as delineated by the Whipple ocular disc. Collectively 

 the squares indicate a typical count in which ten fields were counted as the slide was 

 moved transversely in each of two directions. Five additional fields were selected at 

 random from the remaining quadrants, making a total of 25 (2^2 percent) fields counted. 



accuracy than ±20 percent for the analysis is assumed. This 

 is about as accurate as chlorophyll extraction (Richards and 

 Thompson, 1952),"''^ but is not as critical as gravimetric 

 methods of microplankton analysis (Banse et al, 1963). 

 It was found that the margin of error was not significantly 

 different between the 5 -percent and the 2^-percent counts; 

 therefore, 2-| percent of the fields on each slide were 

 counted. Counts were made by the method illustrated in 

 figure 6. 



13 



