48 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 



Division Chlorophyta 

 Class Chlorophyceae 

 Order Tetrasporales 

 Family Palmellaceae 

 GENUS SPHAEROCYSTIS Chodat, 1897 (fig. 18) 



MORPHOLOGY 



Cells are spherical and are as much as 25 /im in diameter. Cup- 

 shaped chromatophores may fill entire cell. The spherical colony con- 

 sists of groups of 4, 8, 16, or 32 cells arranged toward the periphery of 

 a hyaline, homogeneous envelope. 



REPRODUCTION 



A colonial cell divides into 4 or 8 daughter cells, which are enveloped 

 in a distinct gelatinous envelope. The daugher colony is released by a 

 softening of the parent-colony matrix. 



OCCURRENCE 



The genus is widely distributed in the euplankton. 



ENVIRONMENTAL CONDITIONS 



Standard 

 Range Mean deviation 



Temperature degrees Celsius 0.0 - 33.3 



pH 4.9 - 9.3 



Dissolved oxygen milligrams per liter .4 - 15.9 



Specific conductance micromho 10 -9,800 



Total alkalinity milligrams per liter 6 - 400 



Total hardness do 5 -1,800 



Total nitrogen do .05- 17. n 



Total phosphorus do .0 - 2.8 



SPECIES INFORMATION 



Refer to Smith (1920) and Prescott (1962). 



