M.A. Eggleton and H.L. Schramm, Jr., Mississippi State
University, Department of Wildlife and Fisheries, Mississippi Cooperative Fish and
Wildlife Research Unit, Mail Stop 9690, Mississippi State, Mississippi 39762; Voice
601-325-2073; FAX 601-325-8726;
E-Mail mae3@ra.msstate.edu, hschramm@cfr.msstate.edu.
Keywords: temperate rivers, floodplains, flood-pulse concept,
flooding, warmwater fish
The River Continuum Concept (RCC) of the late 1970's has become widely
accepted as a conceptual framework for stream ecosystem processes. However, research in
tropical and semi-tropical rivers and highly regulated temperate rivers has demonstrated
the integral role of seasonal floodplain inundation on the production ecology of fishes.
Thus, the "flood-pulse" concept adds a lateral dimension to the RCC by
emphasizing the importance of floodplains to fisheries production in large unregulated
rivers. Unlike tropical rivers which may flood 4-8 months annually, most large
free-flowing temperate rivers such as the Lower Mississippi River are characterized by
seasonal climates and at least moderate levels of regulation (levees, dikes) that modify
thermal regimes, restrict annual flood duration, and reduce assimilation of terrestrial
materials during overflow. Although research in the tropics strongly demonstrates a high
dependence of fisheries on seasonal flooding, comparable research in large temperate
rivers is lacking. Use of floodplain resources by fishes in these systems has been little
studied and the "ecological benefit" afforded fishes by floodplain access is
largely speculative except at local scales in a limited number of studies. Temperate river
floodplains may function much differently ecologically than those in tropical rivers.
Thus, application of "flood pulse" concepts may be misguided without
modification or qualification owing to different physical characteristics as compared to
tropical rivers.
