Detecting river environmental quality through plant and macroinvertebrate bioindicators in the Aniene River (Central Italy)

From the source to the mouth of the Aniene River, a tributary of the Tiber near Rome, there is a multifactorial gradient of increasing disturbance and water pollution. We first investigated the variation of riverine and aquatic vegetation along the Aniene, analysing the floristic composition by means of transects comprising both water and shore. We then compared vascular plants and macroinvertebrates to establish which was the more reliable bioindicator of water pollution and disturbance in river habitats. The floristic dataset can be ordered according to the two axes of NMMDS. Axis I showed a high correlation with the Extended Biotic Index (EBI) (Spearman's rho = 0.89) and Hemeroby indicator of disturbance in plants (Spearman's rho = -0.70), and Axis II with Shannon diversity of plants (Spearman's rho = -0.67). These results have been summarised in two GIS maps, for EBI and Hemeroby, and allow to distinguish two sectors of the Aniene: upper and low-middle, correlated with geomorphology, density, type of settlement and degree of pollution. EBI and Hemeroby indicators collect information about environmental quality along different scales.