114 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 



Division Cyanophyta 

 Class Cyanophyceae 

 Order Chroococcales 

 Family Chroococcaceae 

 GENUS ANACYSTIS Meneghini, 1837; emend., Daily, 1942 

 (fig. 51) 



Generic Synonyms. -Microcystis Kiitzing, 1833; Polycystis Kiitzing, 1849; Clathrocystis 

 Henfrey, 1956. 



MORPHOLOGY 



Cells are spherical or almost hemispherical when dividing and range 

 from 2 to 10 fim in diameter. They are irregularly and densely ag- 

 gregated in a free-floating, colonial, gelatinous matrix. Colonies are 

 amorphous. 



REPRODUCTION 



Reproduction is by cell division and colony fragmentation. 



OCCURRENCE 



Anacystis is very common in hard water or eutrophic water during 

 periods of high temperature. It is a frequent component of algal blooms 

 and is notorious as a spoiler of water for domestic uses, swimming, and 

 other forms of recreation. The alga often causes death offish in heavily 

 infested lakes. It is indicative of hard water with high nutrient content 

 when occurring in large numbers with Aphanizomenon or Anabaena. 



ENVIRONMENTAL CONDITIONS 



Standard 

 Range Mean deviation 



Temperature degrees Celsius 0.0 - 



pH 3.7 • 



Dissolved oxygen milligrams per liter .1 - 



Specific conductance micromho 10 



Total alkalinity milligrams per liter 



Total hardness do 2 



Total nitrogen do .00- 



Total phosphorus do .0 - 



SPECIES INFORMATION 



Refer to Daily (1942), Elenkin (1924), Drouetand Daily (1939), Teil- 

 ing (1946), and Prescott (1962). 



