Patterns of Colonization by Macroinvertebrates on Artificial Substrate Samplers: The Effects of Depth

We examined the effect of depth upon the colonization of macroinvertebrates on rock basket samplers employed in the Tennessee River and Pickwick Lake, Hardin County, Tennessee. The number of individuals and the number of taxa on samplers varied proportionately with depth. The mean number of taxa for all paired samplers was 7.3 at 0.5 m and 9.8 at 1.5 m, while the mean number of individuals was 2,528 and 8,691 at 0.5 m and 1.5 m, respectively. The distribution of individuals within genera, within the major taxa Chironomidae, Trichoptera, and Oligochaeta, and within functional feeding groups differed significantly between samplers from different depths, with a greater number of individuals occurring on deep samplers. Speculations are offered regarding reasons for the differences in numbers of organisms between depths.