86 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 



Division Chrysophyta 

 Class Bacillariophyceae 

 Order Pennales 

 Family Naviculaceae 

 GENUS NAVICULA Bory, 1822 (fig. 37) 



MORPHOLOGY 



Cells generally are solitary and free floating but may be aggregated 

 into irregularly radiating clusters. Cells are symmetrical, elongate, and 

 generally attenuated toward the poles. Apices are capitate, rounded, or 

 rostrate. Intercalary bands are lacking. The raphe is straight and cen- 

 tral, and polar nodules are expanded. Striations are transverse, 

 sometimes medially radiate. There are 2 (most commonly) or 4 to 8 

 laminate chromatophores. 



REPRODUCTION 



Two approximate cells each form 2 gametes. Union of gametes 

 results in 2 auxospores. 



OCCURRENCE 



The genus has a widespread distribution and is found in all types of 

 surface waters. Some species are indicative of particular environmen- 

 tal conditions (Patrick, 1948, 1973). According to information included 

 in this report, Navicula is the second most commonly occurring genus 

 in the phytoplankton of the United States. 



ENVIRONMENTAL CONDITIONS 



Standard 

 Range Mean deviation 



Temperature degrees Celsius 0.0 - 



pH 3.4 - 



Dissolved oxygen milligrams per liter .1 - 



Specific conductance micromho 10 



Total alkalinity milligrams per liter 



Total hardness do 3 



Total nitrogen do .00- 



Total phosphorus do .0 - 



SPECIES INFORMATION 



Refer to Boyer (1927a), Cleve (1895), and Patrick and Reimer (1966). 



