HISTORICAL PERSPECTIVE PF TROPHIS STRUCTURE OF THE LOWER OHIO RIVER USING 
STABLE ISOTOPES


Lindsey Rice1, Michael D. Delong1, James H. Thorp2, and Jeffrey R. Anderson3
1Large River Studies Center, Biology Dept., Winona State University, Winona, 
MN 55987.2Kansas Biological Survey, Dept. Ecology and Evolutionary Biology, 
University of Kansas, Lawrence, KS 66407. 3Large River Studies Center, 
College of Science and Engineering, Winona State University, Winona, MN 55987

Most recently have we seen and studied the profound effects humans have on 
ecosystems.  The lower Ohio River ecosystem has been vastly influenced by the 
actions of humans (locks and dams, agricultural runoff, and urban/industrial 
discharge) for decades.  This study is an in-depth examination to determine 
how and to what extent human disturbances have affected riverine trophic 
positions and length of food chain of the lower Ohio River.  Museums contain 
specimens (fish, freshwater snails, and freshwater mussels) from present to 
historic time periods and we can use tissue from these specimens to identify 
changes in stable isotope ratios of carbon and nitrogen in order to help 
determine changes/shifts in trophic levels.  The nitrogen ratio increased 
around 1970 for piscivores but stayed rather consistent for the other trophic 
positions.  Carbon stable isotope ratios slowly decreased from 1920 to 2000.  
Trends in both nitrogen and carbon stable isotope ratios may be correlated 
with human disturbances and its effect on the river’s natural ecosystem.  The 
data collected will not only address the extent of the changes in the 
ecosystem/food webs, but may also give consideration as to if the river’s 
ecosystem is past the point of rehabilitation.

Keywords: food web, stable isotope, food chain, disturbance, temporal

Lindsey L. Rice
Large River Studies Center, Biology Dept., Winona State University, Winona, 
MN 55987
(507)-457-2458
LLRice0752@winona.edu
			
Poster presentation format only

Student