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DEVELOPMENT OF A MULTIMETRIC INDEX FOR ASSESSING THE BIOLOGICAL CONDITION OF THE OHIO RIVER
Citation:
Emery, E. B., T. P. Simon, F H. McCormick, P. L. Angermeier, J. E. DeShon, C. O. Yoder, R. E. Sanders, W. D. Pearson, G. D. Hickman, R. J. Reash, AND J. A. Thomas. DEVELOPMENT OF A MULTIMETRIC INDEX FOR ASSESSING THE BIOLOGICAL CONDITION OF THE OHIO RIVER. TRANSACTIONS OF THE AMERICAN FISHERIES SOCIETY 132(4):791-808, (2003).
Impact/Purpose:
The goal of this research is to develop methods and indicators that are useful for evaluating the condition of aquatic communities, for assessing the restoration of aquatic communities in response to mitigation and best management practices, and for determining the exposure of aquatic communities to different classes of stressors (i.e., pesticides, sedimentation, habitat alteration).
Description:
The use of fish communities to assess environmental quality is common for streams, but a standard methodology for large rivers is largely undeveloped. We developed an index to assess the condition of fish assemblages along 1580 km of the Ohio River. Representative samples of the fish assemblages were collected from 1991 to 2001, using stardardized nighttime boat-electrofishing techniques, from 709 Ohio River reaches, including 318 "least-impacted" sites. We evaluated 55 candidate metrics based on attributes of fish assemblage structure and function to derive a multimetric index of river health. We examined the stability of metrics based against habitat features and assessed the responsiveness of metrics to anthropogenic disturbance, i.e. effluents, turbidity, and highly embedded substrates. The resulting Ohio River Fish Index (ORFIn) comprises thirteen metrics that were selected because they responded predictably to measures of human disturbance or reflected desirable features of the Ohio River. We retained two metrics (number of intolerant species and number of sucker species) from Karr's original Index of Biotic Integrity (IBI). Six metrics were modified from indices developed for the upper Ohio River (number of native species, number of great river species, number of centrarchid species, DELT anomalies, percent individuals as simple lithophils, and percent individuals as tolerant species). We also incorporated three trophic metrics (percent of individuals as detritivores, invertivores, and piscivores, respectively), a metric based on catch-per-unit-effort, and one on the percent of individuals as non-indigenous fish species. The ORFIn declined significantly where anthropogenic effects on substrate and water quality were prevalent and was significantly lower in the first 500m below point-source discharges than at control sites nearby. Although additional research on the temporal stability of the metrics and index will likely enhance the ORFIn's reliability, its incorporation into Ohio River assessments still represents an improvement over current physicochemical protocols.