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Information Storage and Neural Control 



Chlorinity varied from 8.54 to 12.60 parts per thousand, with the 

 surface water generally a little less saline than that near the 

 bottom. The mean gradient for the ten experiments was only 

 0.75 parts per thousand. Temperature ranged from 24°C. in June 

 to over 27 °C. in mid-August, the surface waters being somewhat 

 warmer than the lower strata. The mean temperature gradient 

 was but 0.29 °C. These two variables, clilorinity and temperature, 

 are determinants of water density. In this case, they indicate a 

 very small gradient of increasing density with depth, thus assuring 

 a fair amount of vertical mixing in the water column. This con- 

 clusion is underscored by the vertical distribution patterns of 

 other dissolved substances for which data were obtained — dissolved 



SURFACE 



2 - 



6- 



DEPTH 10 _ 

 (ft) 



14- 



18- 



BOTTOM 



4000 



6000 



MEAN NUMBER OF CELLS 

 ( per ml ) 



Fig. 4. Mean concentrations of living phytoplankters, in counting units ml, 



at various depths. 



