AN EXAMINATION OF PHYTOPLANKTON CONSUMPTION BY GIZZARD SHAD IN POOL 19 OF THE 
MISSISSIPPI RIVER

Lee Ann Brammeier, Lacey Strack, and Susan T. Meiers
Department of Biological Sciences, Western Illinois University, Macomb, 
IL  61455

Though game fish have been more intensively studied in regards to diet, non-game 
fish have been less studied.  In order to understand how planktivorous fish 
affect the phytoplankton communities of the Mississippi River, fish were 
harvested by electroshocking from above Lock and Dam 19 and a small tributary, 
Chaney Creek, in August 2004.  The stomach and intestinal contents of the 
sampled planktivorous fish were harvested and preserved in I2KI for further 
analysis.  For this particular project, we are examining 10 gizzard shad to 
determine the number and species of phytoplankton found in the stomach and 
intestine.  We will compare these data with the number and species of 
phytoplankton in water samples taken at the sampling sites at the time the fish 
were sampled.  Preliminary data suggest that gizzard shad are, to some extend, 
actively choosing particular algae to eat, as the numbers and species 
composition of the stomach and intestine appear to be different.  Upon 
completion of this project, future studies will concentrate analysis of stomach 
and intestine contents of other sampled species that are considered 
planktivorous.

Keywords:  gizzard shad, algae, phytoplankton, Mississippi River, planktivorous 
fish, Lock and Dam 19