The Eutrophication/Pollution Index-Diatom based (EPI-D) and three new related indices for monitoring rivers: The case study of the river Potenza (the Marches, Italy)

The aim of this study was to test three new partial indices correlated to the already known eutrophication/pollution index-diatom global index, all based on diatoms, for assessing the biological quality of the river Potenza. This is an Apennine watercourse that crosses the Marches region and enters the Adriatic Sea. This research complies with the WFD/60/2000/EC, which imposes the combined use of biotic and abiotic aspects in evaluating the ecological status of surface waters. The three partial indices express the sensitivity of diatoms to nutrients (TI-D), organic matter (SI-D), and mineral salts (HI-D). In 13 stations selected along the main watercourse, a total of 133 diatom taxa were found. The results obtained by applying the above-mentioned indices to the diatom communities are expressed numerically on a scale of 1 to 20, where the high values mean good or excellent quality and the low values mean bad quality. All the indices employed showed inverse high correlation with the chemical parameters responsible for organic and mineral pollution and eutrophication, which increase progressively downstream. These indices performed very well in monitoring the river Potenza and showed excellent positive correlation with other diatom indices widely used in Europe.