Benthic Macroinvertebrate Community Structure in a Backwater Lake of Pool 2, Upper Mississippi River

Abstract

The benthic community structure of a backwater lake of the upper Mississippi River was examined based on samples taken in July, 1986. The dominant taxa based on density were the midge Tanypus, followed by the naidid and tubificid oligochaetes and the mayfly Hexagenia. Based on biomass, however, Hexagenia was the dominant taxon. The species found were similar to those reported for other backwater lakes of the Mississippi River, although the relative abundances of various taxa were different. A canonical correlation analysis of habitat factors (based on sediment grain size and organic content) with community characters (densities of all taxa found) indicated that the percent sediment organic matter was the most important factor influencing the presence or absence of various taxa. Sediment particle size had a lesser association with the relative abundance of the major taxa.