Dataset for: Step-by-Step Calculation and Spreadsheet Tools for Predicting Stressor Levels that Extirpate Genera and Species

In 2011, the U.S. Environmental Protection Agency (USEPA) released a field-based method for estimating the extirpation of freshwater aquatic benthic invertebrates by ionic mixtures dominated by HCO₃⁻, SO₄²⁻, and Ca²⁺ measured as specific conductivity (SC). The estimate of extirpation was SC at the 95th centile (XC₉₅) of a weighted cumulative frequency distribution (CFD) of a genus or species over a range of SC. A CFD of XC₉₅ values was used to predict the SC at which 5% of genera were likely to be extirpated. Because there are many uses for XC₉₅ values and many data sets that could be analyzed using this method, we laid out a step-by-step method for calculating XC₉₅ values and the stressor level that predicts a 5% extirpation of genera (HC₀₅). Although the calculations can be done with a hand-held calculator, we provide access to 2 downloadable Microsoft Excel® spread sheet calculation tools that are easy to use to calculate XC₉₅ values, to plot a taxon’s XC₉₅ cumulative frequency distribution with increasing SC, and to plot probabilities of observing a taxon at a particular SC. They also plot cumulative frequency distributions of XC₉₅ values and calculate HC₀₅ values. In addition to the tools, we share an example and the output of XC₉₅ values for 176 distinct aquatic benthic invertebrates in Central Appalachia.