Characterization of Stream Benthic Communities Using Substrate-Filled Trays: Colonization, Variability, and Sampling Selectivity

ABSTRACT

This research examined colonization rate, variability and sampling selectivity of substrate-filled trays collected from six streams (second-sixth order) in Virginia and West Virginia. The length of time required to obtain equilibrium communities in trays varied among streams. Community composition in a second order stream was highly variable among days. In contrast, benthic communities collected from fourth and sixth order streams after 18–20 d colonization were similar to those collected on day 30. These results suggest that longer colonization periods may be necessary to characterize the benthic communities of small streams. Sampling selectivity of substrate-filled trays was examined by comparing relative abundance of dominant taxa in trays and in a natural substrate sampler (0.1 m² Hess sampler). Trays were selective for collector-filterers, which comprised 19–73% of total individuals; however, most dominant taxa present in the natural substrate were also present in trays.

Sampling variability of trays was generally less than or similar to variability of Hess samplers and decreased in larger streams. In two third order streams, 67–125 Hess samples would be necessary to estimate abundance ±10% of the mean compared to 32–56 trays. Because of lower variability and ease of collection, the trays described in this study are a practical alternative to conventional sampling devices and will be useful for assessing the impact of contaminants on benthic communities.