ISSN:
1573-5117
Keywords:
biological indices
;
macroinvertebrates
;
acidification
;
eutrophication
;
statistical power
;
type II error
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Ten benthic macroinvertebrate indicator metrics commonly used in the assessment of running waters (taxa richness, total density, number of EPT taxa, Shannon's index, Simpson's index, ASPT, DFI, and three acidity indices) were evaluated for effect size, standardized effect size, statistical power and the number of samples needed to detect an impact of either eutrophication or acidification. The eutrophication and acidity indices were also evaluated for type I and type II errors. Indices were evaluated using the coefficient of variation of data taken from a spatial dataset of some 700 sites distributed across Sweden, and a temporal dataset of five streams sampled over a time period of 6–11 years. Richness measures (taxa richness and number of EPT taxa) and the two eutrophication indices (ASPT and DFI) had the highest standardized effect sizes as well as a high statistical power and therefore needed fewer samples to detect changes caused by perturbation. Conversely, total density of individuals was the least informative metric with the lowest standardized effect size and the highest spatial, temporal and sample variability.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1017082619481
Permalink
