90 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 



Division Chrysophyta 

 Class Bacillariophyceae 

 Order Pennales 

 Family Naviculaceae 

 GENUS PINNULARIA Ehrenberg, 1840 (fig. 39) 



MORPHOLOGY 



Solitary, free-floating cells are symmetrical, generally straight, and 

 have broadly rounded poles. Girdle view is rectangular; axial view is 

 generally broad and expanded polarly and medially. Girdles are 

 smooth. Intercalary bands are lacking. The raphe is complicated and 

 straight or sigmoid. Costae are tubular openings in the valve wall. Two 

 longitudinal lines are visible in the costae part of the valve. There are 2 

 laminate chromatophores. 



REPRODUCTION 



Two auxospores are formed by the union of 2 gametes from each of 2 

 approximate cells. 



OCCURRENCE 



The genus is widely distributed. It generally is indicative of calm or 

 slowly moving, slightly acid waters having low mineral content. 

 Sometimes Pinnularia is present in abundance in semipermanent or 

 permanent pools of soft-water localities (Smith, 1950). 



ENVIRONMENTAL CONDITIONS 



Standard 

 Range Mean deviation 



Temperature degrees Celsius 0.0 - 33.5 



pH 3.4 - 8.9 



Dissolved oxygen milligrams per liter 1.3 - 15.2 



Specific conductance micromho 20 -43,400 



Total alkalinity milligrams per liter - 430 



Total hardness do 3 - 1,700 



Total nitrogen do .09- 32.0 



Total phosphorus do .0 - 3.9 



SPECIES INFORMATION 



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



