Rheophile Apennine Diatoms and Their Use as Bioindicators of Water Quality

A brief survey of the diatoms found up to now (about 450 taxa) in the watercourses of the Apennines, an imposing mountain chain extending along the Italian peninsula, was made. A particular attention was given to the ecology of these diatoms. As the pH and oxygen are concerned, the alkaliphile and oxyphile forms dominate sharply. In the saprobic spectrum, there is the prevalence of the xenosaprobic and oligosaprobic forms. The halophobe and oligohalobe species dominate in the halobic spectrum, while a more uniform distribution is present in the various levels of the trophic spectrum. In the upper torrential stretches, some species such as Diatoma hyemalis and Eucocconeis flexella occur. They are extremely sensitive to organic and mineral pollution and thus risk disappearing as anthropogenic pressure increases upstream. Nevertheless, on the basis of the data obtained, it seems that the situation of the watercourses here considered is still, as a whole, in moderately good conditions. The high sensitivity of the rheophile diatoms to environmental factors allowed to work out an index for monitoring Apennine rivers, named EPI-D, that has proven quite useful also for rivers of other hydroecoregions, either in Italy or in Europe.