Factors Affecting Fish Assemblages in Floodplain Lakes of the Ouachita River Valley, Arkansas

Floodplain river ecosystems are some of the most diverse and dynamic environments in Arkansas.  These systems are also some of the most disturbed by anthropogenic activity.  The Ouachita River floodplain is unique among Arkansas rivers in that agricultural activity is minimal; but oil and brine extraction and replacement of bottomland hardwoods with pine plantations have been significant disturbances over the last century.  There are approximately 75 natural floodplain lakes in the Arkansas portion of the lower Ouachita River valley, but only 26 are navigable in a powered vessel.  During fall 2013 and 2014, we sampled fish communities in 22 of the 26 accessible floodplain lakes using boat electrofishing.  In addition to fish community data, we measured morphometric and watershed characteristics as well as water quality metrics for each lake.  Relationships among species abundance, diversity indices, trophic guilds, and environmental characteristics were examined using a variety of univariate and multivariate statistical analyses.  Significant factors determining fish community characteristics included maximum depth, surface area, mean width, and distance from the main channel of the river.  Contrary to similar studies conducted in small impoundments, Largemouth Bass abundance had minimal effects on fish community dynamics.