36 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 



Division Chlorophyta 

 Class Chlorophyceae 

 Order Chlorococcales 

 Family Oocystaceae 

 GENUS OOCYSTIS Nageli, 1855 (fig. 12) 



MORPHOLOGY 



Cells are ovoid, ellipsoidal, or cylindrical; 7-45 /*m in diameter; and 

 have smooth walls. A polar nodule may be present. The number of 

 chromatophores varies from 1 to many. The genus may be solitary or in 

 colonies of 2, 4, 8, or 16 cells surrounded by a partially gelatinous and 

 greatly swollen parent-cell wall. 



REPRODUCTION 



Reproduction is asexual into 2, 4, 8, or 16 autospores. Sister 

 autospores remain within the greatly expanded parent-cell wall and 

 may be accompanied by several groupings of sister autospores. New 

 colonies are formed by the rupturing of the parent-cell wall. 



OCCURRENCE 



Oocystis is widely distributed in the euplankton and tychoplankton. It 

 generally is indicative of soft water or oligotrophic water. Some species 

 (for example, Oocystis ellvptica) are commonly found in warm shallow 

 water intermingled among other algae. 



ENVIRONMENTAL CONDITIONS 



Standard 

 Range Mean deviation 



Temperature degrees Celsius 0.0 



pH 4.4 



Dissolved oxygen milligrams per liter 1.7 



Specific conductance micromho 10 



Total alkalinity milligrams per liter 1 



Total hardness do 7 



Total nitrogen do .0( 



Total phosphorus do .0 



SPECIES INFORMATION 



Refer to Smith (1920), Printz (1913), and Prescott (1962). 



