Ickes, B. S., J. Vallazza, J. Kalas, and B. Knights. 2005. River floodplain connectivity and lateral
fish passage: A literature review. U.S. Geological Survey, Upper Midwest Environmental
Sciences Center, La Crosse, Wisconsin, June 2005. 25 pp.

ABSTRACT

Floodplains play a key role in the ecology of the Upper Mississippi River; however, humans have
significantly affected the ecological function of floodplains by isolating them from the main stem
of the river with levees. Impoundment and channel training within the main stem also influence
floodplain function by altering the flow of water through the system. Because of the key role
hydrology plays in floodplain ecosystem function, such effects are frequently conceptualized as
decreases in lateral connectivity, or the hydrologically mediated lateral exchange of energy,
material, and organisms between fluvial and floodplain system components. Some management
practices attempt to reestablish periods of lateral connectivity to mitigate functional losses
associated with isolation and an altered hydrograph. This report presents a review of scientific
literature and synthesis of lateral connectivity as a theoretical and an applied management topic
using fish as a point of focus. On the basis of our review of the literature, we recommend a
framework for adaptive management of lateral connectivity at several scales within the system
and identify data sources that can be used to develop this framework. Specifically, we
recommend the development of a time-sequenced geospatial inventory of Upper Mississippi
River floodplains. Such an inventory is presently being developed by university researchers
investigating changing flood risks in the Mississippi and Missouri River basins. In addition, we
highlight the need for high-resolution floodplain elevation data and the development of a detailed
life-history database for Upper Mississippi River fishes. Finally, we believe that adaptive
management techniques will be critical for developing applied management alternatives for
enhancing lateral connectivity and biotic responses in the Upper Mississippi River Basin. 

KEYWORDS altered hydrology; fish habitat; floodplains; floodplain elevation; lateral
connectivity; lateral fish passage; levees; Mississippi River