Benthic Macroinvertebrates

The benthic macroinvertebrate community downstream of the main storm drains in Mitchell Branch continued to show impacts compared with the upstream reference site (Figure 1). 
Results from 1998 show that construction of the groundwater barriers significantly impacted MIK 0.71 and MIK 0.78. There appeared to be few or no negative effects from this construction on the invertebrate community at MIK 0.45, which is downstream of the zone where the stream was reconstructed. 
Densities were similar at all sites in 1998, indicating benthic invertebrate densities were within the normal range of reference conditions soon after the construction was completed.

Figure 1. Mean density, total taxonomic richness (number of taxa/sample), and taxonomic richness of the pollution intolerant Ephemeroptera, Plecoptera, and Trichoptera (mayflies, stoneflies, and caddisflies or EPT) taxa per sample of the benthic macroinvertebrate community in Mitchell Branch during April sampling periods from 1987-1998.  Samples were not collected in April 1995.

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Last Modified: April 17, 2001