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SIMPLE EMPIRICAL RISK RELATIONSHIPS BETWEEN FISH ASSEMBLAGES, HABITAT AND WATER QUALITY IN OHIO
Citation:
Benjamin, R. B., F A. Fulk, AND S M. Cormier. SIMPLE EMPIRICAL RISK RELATIONSHIPS BETWEEN FISH ASSEMBLAGES, HABITAT AND WATER QUALITY IN OHIO. Presented at Society of Environmental Toxicology and Chemistry, Baltimore, MD, November 11-15, 2001.
Impact/Purpose:
The purpose of this research project is to provide methods, tools and guidance to Regions, States and Tribes to support the TMDL program. This research will investigate new measurement methods and models to link stressors to biological responses and will use existing data and knowledge to develop strategies to determine the causes of biological impairment in rivers and streams. Research will be performed across multiple spatial scales, site, subwatershed, watershed, basin, ecoregion and regional/state.
Description:
To assess the condition of its streams, fish, habitat and water quality data were collected from 1980 to 1998 by the Ohio Environmental Protection Agency. These data were sorted into 190 time/locations by basin, river mile and year. Eighteen fish community variables and 24 habitat or water quality variables were represented in each time/location. Because sample sizes were not constant, the central tendencies for each time/location were described as means (fish and habitat) or as medians (water quality). Approximately one half of the central tendencis were bimodal or multimodal following Box-Cox transformations. Non-parametric analyses of untransformed data simplified data trend analysis and increased statistical robustness. Predictor and response central tendencies were rank ordered and sorted into high, moderate and low categories. Most responses were significantly associated with four to seven predictors as selected by discriminant analyses and confired with Chi-Square tests. For each response variable, one Maximum Response Profile (MRP) was defined as the combination of significant predictor variables resulting in the greatest frequencies of high category responses. A Risk Index (RI) was computed for each of the 18 fish variables at each sampling location. Each RI was the total number of significant, categorized predictors at each time/location not falling into the MRP. Increased RIs were consistently associated with increased frequencies of low-category responses. This is a promising empirical risk assessment tool for use when environmental data are collected from multiple sources.