Detection of ecological change in stream macroinvertebrate assemblages using single metric, multimetric or multivariate approaches

The effects of nutrients on aquatic ecosystems are widespread and trying to understand the reaction of different response indicators is a complex issue. In this study, we used a data set of 21 stream site-samples situated in southern Sweden to assess the strength of single and multimetric indices and multivariate approaches for detecting the effects of nutrient enrichment on stream ecosystems using benthic macroinvertebrate communities. Our results showed both multimetric and multivariate approaches to be reliable tools for detecting the effects of nutrient enrichment on stream macroinvertebrate communities, superior to single metric approaches. In particular, the multimetric DJ index and the multivariate CA scores were sensitive (high coefficients of determination) to the stressor gradient and had high precision (low error). The Saprobic index was the ‘best’ of the six single metric approaches tested here. However, due to differences in the way taxa lists are managed in multimetric and multivariate approaches, we recommend that, if possible, both methods should be used in assessing the effects of nutrient enrichment of stream ecosystems.