Fish species richness in floodplain lakes of the Mississippi Alluvial Valley

Species richness has been used to index the status of aquatic environments, as a baseline for measuring community-level changes, and as a benchmark to assess the success of conservation and management programs.  Richness has been shown to be affected by a variety of environmental factors related to local, regional, and anthropogenic processes.  To identify the major factors controlling species richness in floodplain lakes of the Mississippi Alluvial Valley (MAV), we sampled the fish assemblages in over 50 lakes within selected river basins of Mississippi and Arkansas.  We estimated variability in fish species richness across a diversity of lakes, and relative to fundamental environmental variables including depth, hydrologic connectivity, and landscape composition.  Fish species richness exhibited various levels of response to environmental variables, but the strongest responses were in relation to landscape composition.  Our results suggest that landscape-level processes play a major role in controlling the number of species that inhabit floodplain lakes of the MAV.  Mechanisms by which this control is exerted remain obscure, but several hypotheses are considered.  The observed patterns in species richness related to environmental variables advocate the implementation of proper watershed management practices in order to preserve and restore the fish species richness in floodplain lakes.