Biomonitoring in low-gradient sandy-bottom streams has not been fully addressed. Most biomonitoring methods for benthic invertebrate sample collection and data analyses are for high-gradient cobble-bottom streams. A research project, supplementary to biological sampling of the U.S. Geological Survey's National Water Quality Assessment (NAWQA) program in the South Platte River basin, is comparing benthic invertebrate communities from different habitats using several collection methods. Invertebrates were collected in the Summer of 1993, using the NAWQA program protocols in two types of habitats: (1) richest targeted habitat (commonly submerged woody debris or rocks) and (2) depositional targeted habitat (commonly sandy). Invertebrates were also collected using methods based on the U.S. Environmental Protection Agency's rapid bioassessment protocols in substrates representing three major habitats: (1) submerged woody debris; (2) rocks: and (3) sandy substrates of the main channel. One objective is to determine the variability of benthic invertebrate communities inhabiting different substrates in the sandy reaches of the South Platte River. A second objective is to evaluate several metrics (standard measurements such as number of individuals, number of taxa, percent composition, etc.) from the invertebrate data. These metrics will be analyzed to evaluate whether invertebrate data can be used to distinguish between sites having different water quality in the South Platte River.
Several methods for collecting benthic invertebrates are currently used in the sandy reaches of the South Platte River. Consequently, the ability to compare and integrate results is limited. Results of this research might provide information useful for sampling benthic invertebrates in sandy reaches of the South Platte Basin and other sandy-bottom streams in the semi-arid West. This information might improve the understanding of: (1) variability of invertebrate data related to sampling method; (2) variability of invertebrate data related to habitat; and (3) selection of substrates for future biomonitoring studies.
1 Department of Earth Resources, Colorado State University, Fort Collins, CO 80523
2 U.S. Geological Survey, Box 25046, MS 415, Denver Federal Center, Lakewood, CO 80225