100 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 



Division Chrysophyta 

 Class Bacillariophyceae 

 Order Pennales 

 Family Tabellariaceae 

 GENUS TABELLARIA Ehrenberg, 1840 (fig. 44) 



MORPHOLOGY 



Cells generally are joined into zigzag chains but sometimes into 

 stellate colonies. They are free floating. Valves have numerous inter- 

 calary bands between the girdles. Between the girdles and intercalary 

 bands are longitudinal septa penetrating to the center of the cell. 

 Valves are elongate and have an evident, medial inflation. They are 

 slightly inflated at the poles. There is a narrow pseudoraphe that has 

 lateral, transverse striae. Chromatophores are numerous small discs. 



REPRODUCTION 



Either 1 (Geitler, 1927) or 2 (Schiitt, 1896) auxospores may form 

 within a single cell. 



OCCURRENCE 



The genus is of widespread distribution in the euplankton. The most 

 common species, Tabellaria fenestrata, is indicative of mesotrophic to 

 eutrophic conditions. The genus generally occurs in circumneutral, 

 shallow waters. 



ENVIRONMENTAL CONDITIONS 



Standard 

 Range Mean deviation 



Temperature degrees Celsius 0.0 



pH 3.9 



Dissolved oxygen milligrams per liter 1.2 



Specific conductance micromho 16 



Total alkalinity milligrams per liter 3 



Total hardness do 5 



Total nitrogen do .01 



Total phosphorus do .0 



SPECIES INFORMATION 



Refer to Boyer (1927a) and Patrick and Reimer (1966). 



