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Published in Susan B. Norton, Susan M. Cormier, Glenn W. Suter, Ecological Causal Assessment, 2014
C. Richard Ziegler, Susan B. Norton
For the analysis, the project team focused on three biological statistics (i.e., metrics) that showed conspicuous changes compared with the Red Brook comparison site. The metrics are a subset of those used by the State of Maine to evaluate assemblage quality: number of genera belonging to orders Ephemeroptera, Plecoptera, and Trichoptera (EPT generic richness, abbreviated as “EPT richness” hereafter), and the Hilsenhoff Biotic Index (HBI). EPT richness is often used as an indicator of stream condition (Wallace et al., 1997; see also Bednarek and Hart, 2005). While some individual taxa under the EPT umbrella may be tolerant of particular stressors, EPT are generally more sensitive than other macroinvertebrates to common stressors and often provide a reasonable measure of aquatic environmental quality, that is, greater EPT richness indicates better conditions. Conversely, HBI values often increase as certain aspects of stream condition decline. HBI was originally designed to assess low dissolved oxygen levels caused by organic loading in streams (Hilsenhoff, 1987), but the index may also reflect the presence of other proximate causes. In addition to EPT richness and HBI, the increased proportion of noninsects was evaluated at LCN .415 (proportion of noninsects did not increase at LCMn 2.274, and so was not evaluated there). Table 22.1 summarizes the values of these statistics (see also Box 22.1). Table 22.2 shows the dominant species at the two affected sites and the comparison site.
Effects of forested buffers on benthic macroinvertebrate indicators of water quality in the Western Finger Lakes, New York
Published in Inland Waters, 2021
Mitchell C. Owens, Clayton J. Williams, James M. Haynes
The New York State Department of Environmental Conservation BAP for ponar samples from soft sediments (NYSDEC 2014) was used to assess the water quality experienced by sampled organisms collected by this project’s equivalent sampling method in soft sediments in the 4 focal lakes. The BAP index score was calculated by determining species richness (total number of different taxa identified), Hilsenhoff biotic index (a biotic index calculated using values indicating the overall water quality tolerance of taxa found), dominance-3 (the combined percentage of the sample made up by the 3 dominant taxa), percent model affinity (a measure indicating how well a community fits to an ideal community composition model for a given habitat and sampling method; in this case, a ponar sample), and species diversity (a measure of richness and evenness of taxa found). All indicators were normalized on a 0–10 scale (with 0–2.5 meaning severely impacted, 2.5–5 moderately impacted, 5–7.5 slightly impacted, and 7.5–10 non-impacted) and averaged across indicators to provide one score per sample (NYSDEC 2014).
Assessing measurable adverse changes to benthic invertebrate communities based on site-specific sediment toxicity testing and community data at the Anniston, Alabama PCB site
Published in Human and Ecological Risk Assessment: An International Journal, 2018
Timothy J. Iannuzzi, Bonner Anthony, Alan S. Fowler, Jacqueline Iannuzzi, Derek Pelletier, John R. Loper, John D. Schell
The benthic organisms in each sample were identified to the lowest practicable taxon and characterized in terms of community structure. Six community metrics were calculated using USEPA guidelines (USEPA, 1999): total taxa (richness), the numbers of organisms (abundance), Shannon Wiener diversity (diversity), Hilsenhoff Biotic Index (HBI; tolerance), and taxa and relative numbers of the orders Ephemeroptera (mayflies), Plecoptera (stoneflies), and Trichoptera (caddisflies) taxa (EPT richness and percent EPT, respectively). Since the benthic samples were collected from areas with a similar range of PCB concentrations (no statistically significant difference), the Site community data were pooled and compared to the reference data.