An environmental typology of freshwater sites in Luxembourg as a tool for predicting macroinvertebrate fauna under non-polluted conditions

Macroinvertebrate communities are appropriate quality elements for assessing river health. In Luxembourg, a river typology was first determined on the basis of selected abiotic parameters. Then, a model for predicting the expected fauna was implemented. The deviation of the observed fauna from the expected one was set as an index of river quality. This approach is strongly dependent on the adequacy between the environmental typology and the macroinvertebrate assemblages. The developed model is close to the well-known model RIVPACS but it is constructed on the basis of an abiotic classification of sites instead of a biotic classification used in the latter models and the predicted fauna is assumed to be the community under reference conditions. Results are consistent when compared with other independent biological indices like the Indice Biologique Global Normalisé (I.B.G.N.) and the Intercalibration Common Index (I.C.M.). The chi-squared goodness of fit in order to verify the adequacy of the model also displays good results. This qualitative predictive model is an adequate tool to assess river health even without taking into account abundances of invertebrates.