ZOOPLANKTON IN LAKE PEPIN:  SPATIAL AND TEMPORAL RELATIONSHIPS

Robert M. Burdis1 and Jodene K. Hirsch2   
1Minnesota Department of Natural Resources, LTRMP Lake City Field Station, 1801 
South Oak Street, Lake City, MN 55041. 2Minnesota Department of Natural 
Resources, Ecological Resources, 500 Lafayette Road, St. Paul, MN 55155. 

      Zooplankton is an important prey item in the life history of most fishes 
and often serves as a vital link between trophic levels in aquatic ecosystems. 
Zooplankton is also sensitive to perturbations in aquatic ecosystems that either 
cascade down or result from bottom-up stressors. Lake Pepin provides a unique 
habitat on the Mississippi River for zooplankton due to its morphometry. 
Vertical tows of zooplankton have been collected in Lake Pepin since 1993 in 
conjunction with the Long Term Resource Monitoring Program’s water quality 
sampling effort. Analysis of the data revealed seasonal and spatial patterns in 
the zooplankton community of Lake Pepin. Negative relationships of zooplankton 
density, with chlorophyll and discharge were also evident. 

Keywords: zooplankton, chlorophyll, Daphnia, LTRMP, Lake Pepin