Annual Status Report, 1999: Macroinvertebrate Sampling
Abstract
In 1992, macroinvertebrate sampling was initiated in Pools 4, 8, 13, 26, and the Open River reach of the Mississippi River, and La Grange Pool of the Illinois River as part of the Long Term Resource Monitoring Program Long-term monitoring is needed to detect population trends and local changes in aquatic ecosystems Mayflies (Ephemeridac), fingernail clams (Sphaeriidac), and the exotic Asiatic clam (Corbicula) were selected for monitoring. Midges (Chironomidae) were added to the sampling design in 1993 and zebra mussels (Dreissena polymorpha) were added in 1995. Mayflies, fingernail clams, and midges, members of the soft-substrate community, were chosen because they play an important ecological role in the Upper Mississippi River System. Sampling was based on a stratified random design and was conducted at approximately 125 Sites per study area. Mean densities of tam were weighted by strata for extrapolation purposes. Pool 8 reported the highest estimated mean densities of mayflies and fingernail clams (212 and 506/sq m, respectively). Pool 13 had the highest estimated mean number of midges (234/sq m). Overall, the impounded areas (including Lake Pepin) and the contiguous backwaters tended to support the highest mean densities of mayflies, fingernail clams, and midges in the upper portion of the study area. Substrates with predominantly a silt clay constituent supported the highest mean densities of mayflies, fingernail clams, and midges.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 2000
- Accession Number
- ADA378284
Entities
People
- Jennifer S. Sauer