Table 2. Percent frequency of dominance of algae taxa at all 

 stations in the Yellowstone River. 



Taxa 



Bacillariophyceae (Diatoms) 



Cladophora glomerata 



Enteromorpha 



Spirogyra 



Hydrurus foetidus 



Stigeoclonium 



Phormidium 



♦These columns will not add to 100 percent because a clearly dominant 

 taxon was not evident in all plankton samples. 



Distribution . The frequency of occurrence of the 19 most common 



non-diatom algae at the 19 Department of Fish and Game Yellowstone 



River sampling stations is exhibited in Table 3. (A key to these 19 



taxa is provided in Appendix D.) Only Cladophora glomerata occurred 



at all 19 stations from Corwin Springs to Cartwright, North Dakota, 



Most of the other taxa showed a preference for one or two sections of 



the river. The first six taxa in Table 3-- Enteromorpha , Microspora , 



Hydrurus foetidus , Ulothrix and Oedo^onjum- -achieved their greatest 



development in the upper river. Most of these are typically cold water 



taxa. The next five taxa appeared to be evenly distributed in the 



upper and middle river with little representation in the lower river. 



These are followed by seven taxa, including Cladophora glomerata , 



which appeared in all three reaches of the river and did not clearly 



prefer one reach over the other two. Only one taxon, Staurastrum . 



was exclusively characteristic of the lower Yellowstone River. 



■12- 



