Biomonitoring through biological traits of benthic macroinvertebrates: how to use species trait databases?

The aim of this paper was to investigate the potential use of biological and ecological traits of macroinvertebrates as indicator systems of quality conditions in freshwater ecosystems. To provide a framework for the trait analysis, a data base was developed; it stored biological information about 472 benthic macroinvertebrate taxa. Twenty-two variables describing biological and ecological traits were resolved into a number of simple attributes. A fuzzy coding procedure was used to describe the link between taxa and variables. Three strategies, using simple descriptive statistics or multivariate ordination techniques, were examined in their abilities to demonstrate some of the characteristics of the environment and to bring out clear information on the rate of changes in habitats. We used the Loire River, France, as a specific example. Like faunal analyses, trait analyses showed that a major change occurred in the community in the upper reaches of the river, but transition zones that were not detected with faunal data alone, were discriminated. They corresponded to differences in combinations of biological and ecological traits of communities and were linked to tributary influences (e.g. the Allier-Loire confluence) or anthropogenic disturbances: dams (Grangent, Villerest) or urban zones (Le Puy, Tours). We concluded that the species trait approach had the potential to evaluate the actual state of ecosystems, to discriminate among different types of human impact, and to develop monitoring tools considering the functional diversity of communities.