Date of Award

2010

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Biology

Abstract

Population, community and functional measures or metrics in rapid bioassessment programs aid in establishing biological criteria for streams and rivers. Each metric measures different aspects of community structure and is important in detecting changes in macroinvertebrate community structure that are influenced by changes in water quality. In this study, temporal variation of nine commonly used bioassessment indices was examined in three midwestern streams. The indices were calculated for each of nine replicate benthic macroinvertebrate samples collected monthly for one year from Cowpie Creek (CC), Nippersink Creek (NC) and Lawrence Creek (LC), McHenry County, Illinois. In practice, the habitat sampled for bioassessments often is limited to riffle sites in an attempt to reduce spatial variability in the indices and midges (Diptera: Chironomidae) often are omitted to remove error associated with sampling, identification and variable life histories. Where appropriate, indices in this study were calculated using all sites, using only riffles areas, using all macroinvertebrates, and using all macroinvertebrates exclusive of Chironomidae. Sites were ordinated by Detrended Correspondence Analysis (DCA) to reveal temporal trends among index ratings. In assessments using all sites, biotic indices reflected temporal changes in macroinvertebrate community structure differently than the multimetric index and taxa richness metrics. When only riffle sites were included in assessments, the ability of indices and metrics to reflect macroinvertebrate community structure was dependent on the community assessed, improving in some streams but not in others. Similarly, the omission of Chironomidae from assessments resulted in differing abilities of the indices to reflect macroinvertebrate community structure. Because the indices showed poor performance in some streams when assessing riffle sites or omitting midges from assessments, it was concluded that all habitats and all macroinvertebrates should be included in assessment protocols. Although multimetric indices provide more information about stream communities than biotic indices, the use of ordination analyses are helpful in verifying accuracy of water quality assessments.

Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License.

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