[Application of the biotic index and the diversity index to the study of macro-benthons in a river]

Using the Biotic Index and the Diversity Index the results are analysed of a study of the macrobenthic community sampled in the course of one year at three stations along he lowest-lying stretch of the River Simeto. The results obtained from applying the two different indices are not in perfect agreement one with the other. Whereas with the Biotic Index one could be led to consider the fluvial environment situation a good one, the Diversity Index shows the environment to be partially compromised by organic substances. On the basis of results of chemico-physico-microbiological analyses as well as data concerning the nutritive habits of the species found, we conclude that the Diversity Index is a more suitable instrument for measuring the biological reality of the Simeto.