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Communication at the NABS Annual meeting, Keystone, 2000
(64) DETERMINING APPROPRIATE BIOLOGICAL IMPAIRMENT THRESHOLDS: THE MEANING OF IMPERFECT INFORMATION.
J.B. Stribling, J. Gerritsen, and M.T. Barbour. Tetra Tech, Inc., 10045 Red Run Blvd., Suite 110, Owings Mills, MD 21117
Methods exist that allow sampling, analysis, and interpretation of biological data in the context of geographically- calibrated (regionalized) reference conditions. Further, relatively minimal sample replication provides quantitative estimates of precision (e. g., known confidence) associated with assessments. Nonetheless, continuous debate persists on data quantity and quality needed for decisions on relative ecosystem condition. This paper briefly presents biological index development results in Maryland, Wyoming, and Arizona based on benthic macroinvertebrate sampling and analysis, and their technically-solid biological thresholds used to make decisions on relative impairment. We provide comparisons between objectively-formulated impairment thresholds and those conceptual thresholds that would indicate self-sustainability of ecosystems. We argue that characterization of decision thresholds for ecological sustainability depend on conceptual definition of sustainability, threshold relationship to societal values, and availability of resources to gather appropriate information. There are no ecological databases or ongoing data collection efforts comprehensive enough to completely characterize ecological thresholds that, below which, an ecosystem cannot sustain and/or repair itself. However, we provide rationale that multimetric-based impairment thresholds (such as Maryland's Benthic Index of Biotic Integrity and Wyoming's Stream Integrity Index) are acceptable and provide quantitatively-defined goals that (if managed for) move streams in the direction of natural and self-sustaining ecological systems.
Presented at 8:30 AM on Tuesday, May 30, 2000 in Determining Good Sites from Bad I
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