A Macroinvertebrate Bioassessment of Water Quality and Land Use in the Piasa Creek Watershed PDF Download

Author: Kirk Lambrecht
Publisher:
ISBN:
Category : Piasa Creek Watershed (Ill.)
Languages : en
Pages : 236

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Book Description
"The Piasa Creek Watershed (PCW) was once a landscape historically comprised of forest and prairie habitat, but today is largely comprised of agriculture and urban lands. Studies carried out in the watershed have shown stream biology, mainly fish, and water quality to have declined over time. In the PCW, macroinvertebrate bioassessments of water quality and land use have largely been underutilized. Benthic macroinvertebrates were sampled during October 2011 from riffle habitats at 19 unique locations throughout the PCW in order to examine water quality as a function of land use. Collections were based on rapid bioassessment procedures with a minimum of 125 organisms sampled and identified to the family level, and summarized using a suite of metrics. Water quality ratings were determined using the Hilsenhoff Biotic Index (HBI) which incorporated regional pollution tolerance values. Data analyses with multiple regression were used to evaluate relationships between macroinvertebrate metrics and land use coverage. Non-metric multi-dimensional scaling (NMDS) of community assemblages in combination with vector fitting procedures were employed to evaluate the effects of land use on communities. Data interpretation was assisted with the use of an analysis of similarity between communities of different stream orders and an indicator species analysis. Communities were obtained from 3rd through 6th order streams. In total, 5,345 organisms from 56 unique families of benthic invertebrates were identified. Predominant land uses included grass/pasture, agriculture, forest, and urban cover types. On average, water quality was rated as "fair" but ranged from "good" to "poor" using the HBI scale. Communities differed by the percentage of agriculture and forest land use in each watershed, as well as stream order, with those from 3rd order streams different from higher orders. Certain families of invertebrates discriminated among groups of stream sites, six families were indicative of 3rd order streams and two taxa were indicative of sites from higher orders. While the lack of significant relationships between land use and macroinvertebrates is weak, the results are based on a relatively small sample size which may have limited the scope of findings. Overall, the composition of macroinvertebrate communities in the PCW suggests water quality is impaired to some extent. An increase in the percentage of agricultural land cover affected community composition, and this land use is at least partially the source of water quality impairment. Additionally, community composition was also influenced by the percentage of forest land cover, and sites with the best water quality contained watersheds of mostly forest habitat. The relationship between land use and community composition is likely influenced by changes to riparian and in-stream habitat in addition to water quality. Stream systems in the PCW are likely influenced by land use at multiple spatial scales, however, findings from this study suggest the relationship does in fact extend to the watershed level. While addressing water quality and stream habitat issues in the PCW is a complex task, it may be beneficial to employ best management practices at key areas further out in the watershed to address water resource needs in the PCW."