Role of macrophyte communities as bioindicators of water quality: application on the Tiber River basin (Italy)

The aquatic plant communities of the Tiber River basin have been examined to evaluate their role as bioindicators of the water quality of the Italian peninsular rivers. The compatibility curves of phytocoenoses to water chemico-physical gradients show a correlation between the distribution pattern of the vegetation types and the water’s chemico-physical features, such as different levels of water pollution. In particular, Fontinaletum antipyreticae, Ranunculo-Sietum, Elodeo-Potametum crispi and Nasturtietum officinalis develop in meso-eutrophic and fairly clean water, Potamogeton nodosus community and Ceratophylletum demersi in eutrophic water of medium quality, while Myriophylletum spicati and especially Potametum pectinati and algal communities with Entheromorpha flexuosa are found in hypertrophic water of poor quality. These phytocoenoses can be utilised as valid bioindicators of water quality. On the contrary, Callitrichetum stagnalis, Myriophylletum verticillati, Najadetum marinae and algal communities with Cladophora glomerata are not effective bioindicators, showing a wide and sometimes unclear synecology.