22 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 



Division Chlorophyta 

 Class Chlorophyceae 

 Order Chlorococcales 

 Family Coelastraceae 

 GENUS COELASTRUM Nageli, 1849 (fig. 5) 



MORPHOLOGY 



Cells are spherical, ovoid, or pyramidal and range from 3 to 25 fim in 

 diameter. Chromatophores are cup shaped to diffuse. Coenobia 

 generally are hollow spheres consisting of 4, 8, 16, 32, 64, or 128 cells 

 connected by processes of varying length. Sheath is very delicate. 



REPRODUCTION 



One or more cells in the colony divides into 4, 8, 16, 32, 64, or 128 

 autospores that remain united. The newly formed colony is released by 

 bipartition or quadripartition of the parent-cell wall (Crow, 1925). Oc- 

 casionally, a cell develops into an aplanospore, which is released prior 

 to division into a new colony. 



OCCURRENCE 



The genus is widely distributed in slowly moving waters. It is an in- 

 significant component of algal communities indicating eutrophic condi- 

 tions. It often is found sparingly intermingled with other algae in pools 

 and ditches (Smith, 1950). 



ENVIRONMENTAL CONDITIONS 



Standard 



Range Mean deviation 



Temperature., degrees Celsius__ 0.0 - 34.0 22.2 6.0 



pH__ 4.2 - 9.4 7.7 .6 



Dissolved oxygen milligrams per liter , .4 - 19.7 8.1 2.2 



Specific conductance micromho . 10 -35,500 808 1,660 



Total alkalinity milligrams per liter__ - 390 120 71 



Total hardness _ do ' 6 - 1,400 212 200 



Total nitrogen do .07- 19.0 1.67 1.90 



Total phosphorus _. do .0 - 3.4 .2 .3 



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 SPECIES INFORMATION 



Refer to Ducellier (1915), Brunnthaler (1915), and Prescott (1962). 



