EFFECTS OF SAMPLE-SIZE (REPLICATE NUMBER) ON SIMILARITY MEASURES IN RIVER BENTHIC AUFWUCHS COMMUNITY ANALYSIS

The effects of sample size (the number of replicates) on 11 similarity measures were investigated using a set of freshwater macroinvertebrat e samples and a randomization procedure for resampling. Most of these indices were strongly affected by sample size. However, as sample size increased, species composition and relative abundance changed signifi cantly and the real similarity between two replicate samples increased substantially. Responsiveness to sample size dictates the sensitivity of a similarity measure to community change. The relative independenc e of sample size of some similarity measures results from strongly ove rweighting abundant species. CY dissimilarity similarity measure showe d the highest sensitivity, followed by Canberra metric.