Habitat preference of aquatic macroinvertebrates in an east Texas sandy stream

摘要

I identified the habitat types available to macroinvertebrate colonization in an east Texas sandy stream and then described differences in colonization of those habitat types. Six habitat types were identified in Harmon Creek: aquatic macrophytes; (Hydrocotyle umbellata, Justicia ovata, Alternantha philoxeroides), coarse woody debris (CWD), leaf packs, submersed roots extending from riparian trees, submerged macrophytes (Najas guadalupensis) growing on bedrock (Najas/bedrock), and benthic sand. One-way analysis of variance showed significant differences in macroinvertebrate density among habitat types. The greatest density was found on macrophytes (815.8 organisms/m(2)) followed by CWD (679.7 organisms/m(2)). The third greatest densities were found on leaf packs (516.1 organisms/m(2)) and roots (492.5 organisms/m(2)), which were not significantly different from one another. Lowest densities were collected from Najas/bedrock (218.6 organisms/m(2)) and benthic sand (2163 organisms/m(2)). Coarse woody debris also showed significant differences in macroinvertebrate density with degree of wood decay. Wood with loose bark, and well-decayed wood with many interstitial spaces had the greatest density of macroinvertebrates. Macroinvertebrate richness was highest in leaf packs, which contained 46 genera of macroinvertebrates, and the lowest richness occurred on Najas/bedrock, which contained 24 genera.