Effects of Land Use and Associated Factors On Biological Communities of Small Streams in the Illinois River Basin of Arkansas

The Illinois River Basin of Arkansas is an area with substantial and rapid land use changes, rapid population growth, and associated water-quality and stream habitat effects. Small streams (generally ranging from about 15 to 25 square miles) in the Illinois River Basin of Arkansas were sampled in 2011 and 2012 (primarily in July and August of 2011) at 18 sites for nutrients and periphyton, macroinvertebrate, and fish communities.  Macroalgae cover, stream reach habitat, and several land use factors were measured. Some metrics associated with periphyton, macroalgae, macroinvertebrate, and fish communities were correlated (Spearman’s rho) with land use (for example, percent forest, agriculture, and urban land in the basin) and factors often associated with land use (such as water quality, substrate embeddedness, riparian shading, and channel geometry).  Some metrics associated with the biological communities also appear to be affected by upstream wastewater-treatment plants. Examples of metrics affected by these factors and by wastewater-treatment plants include biovolume of blue-green algae and diatoms (although total biovolume was not correlated with these factors), percent cover of macroalgae, Ephemeroptera-Plecoptera-Trichoptera abundance, and a fish index of biotic integrity previously developed for the Ozarks.