found in the other reaches. All of the organisms collected in this reach 

 were quite small. Most of those collected were oligochaetes and midge 

 larvae (Tendipedidae) . 



Lower-Middle Reach . The lower-middle reach was represented by 

 k2 samples taken at mile 90-5^ laile 62.6, and mile 37.2. This stretch 

 of river is characterized by a rather uniform seuady bottom this quite 

 unproductive of bottom organisms. The nvunbers of organisms per unit of 

 area were lower in this reach of the river than in emy of the others, 

 but the volume was higher than in the upper-middle reach. The collection 

 of a few large clams, Corbicula , was primarily responsible for the increased 

 volume over the reach Immediately upstream. There was little veiriety 

 in types of organisms present. Most of those collected were clams, 

 oligochaetes, and midge larvae. 



Lower Reach . The lower reach is located in an area heavily 

 influenced by tidal action. Bottom material is composed of sand, silt, 

 and organic matter. The kl samples collected at mile l8.8, mile 12.8, 

 and mile k.O were used to characterize this reach. This reach contained 

 approximately two-thirds as many organisms per square foot as the upper 

 reach, but the volume of these orgauiisms was just over one-half as much 

 as those from the upper reach. Numbers and volume, however, were greater 

 in this reach than in either of the middle reaches. There were few kinds 

 of different organisms present. Most of those collected were clams, amphipods, 

 oligochaetes, suid midge laxvae. 



Seasonal Variations 



Detailed seeisonal variations in population density and composi- 

 tion have not been evsLluated. An examination of the total numbers of 



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