The structure of aquatic macroinvertebrates communities reflects the quality of water over time. To determine the influence of water quality on macroinvertebrates, we analyzed the correlations between the general physical and chemical parameters and four biological indices calculated on the basis of macro-invertebrates. Samples of water and macroinvertebrates were taken from six sections located on the middle and lower course of the Siret River for a period of four years. We analyzed the linear relationship between physicochemical parameters and biological indices and we have obtained significant correlations between them. Knowing these correlations, we can predict the evolution of the macro-invertebrates structure according to changes in the chemical structure of the water.
