Influence of a forest preserve on aquatic macroinvertebrates, habitat quality, and water quality in an urban stream

摘要

The use of nature areas as an effective tool for conservation of streams and their biota is a relatively unexplored option in urban stream management. Benthic macroinvertebrates and water quality in an urban stream, Poplar Creek, were monitored along a continuum within and downstream of a forest preserve in the western Chicago metropolitan area, USA. Taxa richness and a benthic macroinvertebrate index of biological integrity (MIBI) increased as the stream progressed within the preserve, but percentage of Ephemeroptera, Trichoptera, and Plecoptera (%EPT) showed no improvement. Reductions in the amount of silt substrates and increases in gravel-dominated substrate were evident at sites within the preserve. There were no improvements in water-quality measures tested although trends may have been obscured by precipitation events between sampling occasions. The benefits in stream quality attained within the forest preserve extended beyond the downstream border of the preserve and were not diminished by the presence of a railway, which bisected the stream. The nature preserve provided an opportunity for increased macroinvertebrate biodiversity, likely through local reductions in impervious surfaces and improvements in stream substrate, despite lack of evidence that it improved water quality.