18 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 



Division Chlorophyta 

 Class Chlorophyceae 

 Order Volvocales 

 Family Chlamydomonadaceae 

 GENUS CHLAMYDOMONAS Ehrenberg, 1833 (fig. 3) 



MORPHOLOGY 



Actively motile solitary cells are ovoid, spherical, fusiform, or ellip- 

 soidal and range from 3 to 10 ^m in diameter. Two equal-lengthed 

 flagella are located at the anterior end. Cell contains a single, cup- 

 shaped chromatophore and contractile vacuoles. Eyespot may or may 

 not be present. 



REPRODUCTION 



The alga reproduces both asexually and sexually. Asexual reproduc- 

 tion is by longitudinal division into 2, 4, or 8 daughter cells, which are 

 enveloped in an amorphous gelatinous wall. Continued division results 

 in the palmella stage. Cells develop flagella and escape through the 

 parent-cell wall. Species may be homothallic or heterothallic, and 

 gametic union may be isogamous, anisogamous, oogamous. 



OCCURRENCE 



The alga occurs commonly in the euplankton and tychoplankton as 

 solitary, free-swimming cells. It has a widespread distribution, but 

 generally it is found in calm or very slowly moving waters. 



ENVIRONMENTAL CONDITIONS 



Standard 

 Range Mean deviation 



Temperature degrees Celsius 0.0 - 36.5 



pH 4.1 - 9.8 



Dissolved oxygen milligrams per liter .1 - 22.0 



Specific conductance micromho 10 -49,800 



Total alkalinity milligrams per liter - 500 



Total hardness do 3 - 2,000 



Total nitrogen do .00- 26.0 



Total phosphorus do .0 - 4.0 



SPECIES INFORMATION 



Refer to Pascher (1927), Gerloff (1940), and Prescott (1962). 



